ALBERT

Description: A tsunami earthquake is defined as a shock which generates extensive tsunamis but relatively weak seismic waves. A comparative study is made for the two recent tsunami earthquakes, and a subduction mechanism near a deep-sea trench is discussed. These two earthquakes occurred at extremely shallow depths far off the coasts of the Kurile Islands and of eastern Hokkaido on October 20, 1963, and on June 10, 1975, respectively. Both can be regarded as an aftershock of the preceding larger events. Their tsunami heights and seismic wave amplitudes are compared with those of the preceding events. The results show that the time constants involved in the tsunami earthquakes are relatively long but not long enough to explain the observed disproportionality between the tsunamis and the seismic waves. The process times are estimated to be less than 100 s. The spatio-temporal characteristics of the two events suggest that they represent a seaward and upward extension of the rupture associated with a great earthquake which did not break the free surface at the coseismic stage. The amplitude and phase spectra of long-period surface waves and the long-period P waveforms indicate that this extension of the rupture did not take place entirely along the lithospheric interface emerging as a trench axis. It rather branched upward from the interface in a complex way through the wedge portion at the leading edge of the continental lithosphere. This wedge portion consists in large part of thick deformable sediments. A large vertical deformation and hence extensive tsunamis result from such a branching process. A shallowest source depth, steepening of rupture surfaces, and a deformable nature of the source region all enhance generation of tsunamis. The wedge portion ruptured by a tsunami earthquake is usually characterized by a very low seismic activity which is presumably due to ductility of the sediments. We suggest that this portion fractures in a brittle way to generate a tsunami earthquake when it is loaded suddenly by the occurrence of a great earthquake and that otherwise it yields slowly. Upward branching of the rupture from the lithospheric interface produces permanent deformation of the free surface which is relative uplift landward and relative subsidence trenchward of the zone of surface break. This surface break zone geomorphologically corresponds to the lower continental slope between the deep-sea terrace and the trench. Such a mode of permanent deformation seems to be consistent with a rising feature of the outer ridge of the deep-sea terrace and a depressional feature of the trench. This consistency implies a causal relationship between great earthquake activities and geomorphological features near the trench.

Description: A tsunami earthquake is defined as a shock which generates extensive tsunamis but relatively weak seismic waves. A comparative study is made for the two recent tsunami earthquakes, and a subduction mechanism near a deep-sea trench is discussed. These two earthquakes occurred at extremely shallow depths far off the coasts of the Kurile Islands and of eastern Hokkaido on October 20, 1963, and on June 10, 1975, respectively. Both can be regarded as an aftershock of the preceding larger events. Their tsunami heights and seismic wave amplitudes are compared with those of the preceding events. The results show that the time constants involved in the tsunami earthquakes are relatively long but not long enough to explain the observed disproportionality between the tsunamis and the seismic waves. The process times are estimated to be less than 100 s. The spatio-temporal characteristics of the two events suggest that they represent a seaward and upward extension of the rupture associated with a great earthquake which did not break the free surface at the coseismic stage. The amplitude and phase spectra of long-period surface waves and the long-period P waveforms indicate that this extension of the rupture did not take place entirely along the lithospheric interface emerging as a trench axis. It rather branched upward from the interface in a complex way through the wedge portion at the leading edge of the continental lithosphere. This wedge portion consists in large part of thick deformable sediments. A large vertical deformation and hence extensive tsunamis result from such a branching process. A shallowest source depth, steepening of rupture surfaces, and a deformable nature of the source region all enhance generation of tsunamis. The wedge portion ruptured by a tsunami earthquake is usually characterized by a very low seismic activity which is presumably due to ductility of the sediments. We suggest that this portion fractures in a brittle way to generate a tsunami earthquake when it is loaded suddenly by the occurrence of a great earthquake and that otherwise it yields slowly. Upward branching of the rupture from the lithospheric interface produces permanent deformation of the free surface which is relative uplift landward and relative subsidence trenchward of the zone of surface break. This surface break zone geomorphologically corresponds to the lower continental slope between the deep-sea terrace and the trench. Such a mode of permanent deformation seems to be consistent with a rising feature of the outer ridge of the deep-sea terrace and a depressional feature of the trench. This consistency implies a causal relationship between great earthquake activities and geomorphological features near the trench.

Description: Helium isotope measurements in six major basins in the Gulf of California show that the deep Guaymas Basin has 3He/4He 65–70% higher than atmospheric helium, clear evidence of mantle helium injection. Smaller 3He excesses observed in the Carmen and Farallon basins may be derived from this Guaymas Basin anomaly. The 3He concentrations in the Mazatlan Basin in the mouth of the Gulf of California are similar to average eastern Pacific values, indicating that the Gulf does not provide a significant flux of 3He into the general Pacific circulation. On the basis of temperature and salinity measurements an upper limit of 0.28°C can be placed on the amount of geothermal heating observed in any of the basins. The isotopic ratio of the injected Guaymas Basin helium is found to be 3He/4He = (1.10±0.06) × 10−5, almost identical to the helium signature observed at the Galapagos Rift but somewhat lower than the average ratio in oceanic basalt glasses.

Description: One hundred and five new heat flow measurements in the Gulf of California support the premise that conductive heat loss is not the only mode by which heat is lost from a sea floor spreading center, even in an area with thick sediment cover. Theoretical estimates suggest that the average heat flow in the Guaymas and Farallon basins should be at least 11 μcal/cm2 s (HFU) (325 mW/m2). Outside a 30-km-wide zone centered on the central troughs, the heat flow values measured are reasonably uniform but average only 4.3±0.2 HFU (180±10 mW/m2). Although the high sedimentation rate may depress the measured heat flow, the effect probably does not exceed 15%. Some heat, particularly in the smaller basins, may be lost to the adjacent cooler continental blocks. The discrepancy between the measured and predicted heat losses, which is at least 30%, may be due to the discharge of thermal waters, through the thinner sediment cover in the central troughs or along active faults.

Description: Fifty-four new heat flow measurements in the central troughs of the Guaymas basin support the hypothesis that they are sites of active intrusion. In the northern trough a distinct pattern of hydrothermal cooling is revealed, with venting along the western boundary fault of the trough. In the southern trough an analogous pattern is apparently superimposed upon a conductive cooling anomaly associated with a recent central intrusion. The discharge of thermal waters occurs along the boundary faults and through other faults associated with a possible horst block located in the north central floor of the southern trough. The heat flow patterns suggest that the intrusions are episodic and do not occur simultaneously along the length (15–40 km) of a spreading segment. A review of all available heat flow measurements for the Guaymas basin suggests that most of the recharge for a pervasive regional hydrothermal system is limited to the central depressions, with perhaps some contribution from pore water. The discharge of thermal waters occurs predominantly in the central depressions and possibly along the boundary transform faults and fracture zones. The regions of the basin more than a few kilometers in distance from the spreading axis, although presumably underlain by a hydrothermal system, are probably not the location of numerous vents or recharge zones.

Description: The structural evolution of the northwestern Iberian margin has been reconstructed from the results of IPOD drill site 398, as well as from numerous dredgings and a dense network of seismic profiles. During the Mesozoíc the margin first underwent two consecutive extensional phases interpreted as the result of two episodes of rifting in the Atlantic. Then during Eocene, subsidence was interrupted by compression and related deformation caused by subduction of oceanic sea floor of the Bay of Biscay beneath the Iberian Peninsula. Present day marginal banks are interpreted as blocks of the older passive margin uplifted during early Tertiary as a result of that subduction. Fault escarpments provide opportunities to sample older sediments and basement by dredging.

Description: Studies of the last 125 million years of oceanographic and climatic history have benefited greatly from the impetus provided by the Deep Sea Drilling Project. Knowledge of the sedimentary and paleontologic record of the major ocean basins, in conjunction with study of pelagic marine sections exposed on land, has permitted both the testing of old and the development of new hypotheses to explain local and global ocean chemical, sedimentologic and biotic events. Some of the more striking and topical problems in paleoceanography are the oceanic “anoxic events” of early to middle Cretaceous age, the biotic crisis at the Cretaceous/Tertiary boundary, the Eocene/Oligocene extinctions and climatic and circulation events, the Messinian “salinity crisis” (late Miocene) and its effects on the world ocean, and Pleistocene glacial cycles and paleoceanography. Possible explanations of these events, which have been proposed over the last five years, are reviewed in this paper.

Description: The olivine melilitite diatemes of the Swabian Alb, frequently compared with kimberlite diatremes, are discussed in terms of hydrogeological setting, internal structure and juvenile fraction. The hydrogeological conditions of the Swabian Alb at the time of diatreme emplacement were characterized by copious amounts of groundwater within the sedimentary cover of the basement. Subsequently to the eruptions groundwater accumulated within the maars of the larger diatremes forming fresh‐water lakes as also happened nearby in the Steinheim and Ries impact craters. The diatremes reveal subsidence structures composed of large wall‐rock blocks, subaerially deposited pyroclastic beds, and well‐bedded reworked pyroclastic debris which accumulated on the floor of the fresh‐water crater lakes. The latter fact implies availability of groundwater at the time the diatremes formed. The juvenile fraction is developed in the shape of spherical to ovoid nucleated autoliths of ash to lapilli size that are macroscopically nearly devoid of vesicles. The autoliths are interpreted as the product of water vapor explosions which took place when rising olivine melilitite magma contacted groundwater and was fragmented into magma droplets. The droplets were rapidly chilled and thus preserved their shape. Because of the hydrogeological data, the diatreme structure, and the chilled nature of the autoliths a phreatomagmatic origin of the Swabian diatremes is suggested.

Description: The olivine melilitite diatemes of the Swabian Alb, frequently compared with kimberlite diatremes, are discussed in terms of hydrogeological setting, internal structure and juvenile fraction. The hydrogeological conditions of the Swabian Alb at the time of diatreme emplacement were characterized by copious amounts of groundwater within the sedimentary cover of the basement. Subsequently to the eruptions groundwater accumulated within the maars of the larger diatremes forming fresh‐water lakes as also happened nearby in the Steinheim and Ries impact craters. The diatremes reveal subsidence structures composed of large wall‐rock blocks, subaerially deposited pyroclastic beds, and well‐bedded reworked pyroclastic debris which accumulated on the floor of the fresh‐water crater lakes. The latter fact implies availability of groundwater at the time the diatremes formed. The juvenile fraction is developed in the shape of spherical to ovoid nucleated autoliths of ash to lapilli size that are macroscopically nearly devoid of vesicles. The autoliths are interpreted as the product of water vapor explosions which took place when rising olivine melilitite magma contacted groundwater and was fragmented into magma droplets. The droplets were rapidly chilled and thus preserved their shape. Because of the hydrogeological data, the diatreme structure, and the chilled nature of the autoliths a phreatomagmatic origin of the Swabian diatremes is suggested.

Description: The pollen record of three marine late Quaternary cores off Senegal shows a juxtaposition of Mediterranean, Northern Saharan, Central Saharan elements, which are considered transported by the trade winds from a winter-rainfall area, and Sahelian, Soudanese, Soudano-Guinean elements, considered transported both by winds and mostly by the Senegal River, and coming from the monsoonal, summer tropical rainfall area of southern West Africa. Littoral vegetation is either the edaphically dry and saline Chenopodiaceae from sebkhas at the time of the main regression, or the warm tropical humid mangrove with Rhizophora during the humid optimum period. Four stratigraphic zones reflect, from basis to top: Zone 4. A semi-arid period with a balanced pollen input. Zone 3. A very arid period with the disappearance of monsoonal pollen, probably from the disappearance of the Senegal River, a very saline littoral plain with Chenopodiaceae, a larger input of northern Saharan pollen from intensified trade winds. Zone 2. A quite humid period, much more so than today, very suddenly established, with a northward extension of the monsoonal areas, a rich littoral mangrove, and weakening of the trade winds. Zone 1. A slow and steady evolution toward the present semi-humid conditions with regression of the mangrove, and of the monsoonal areas toward the south. Tentative datations and correlations with the Tchad area suggested: zone 4: 22,500 to 19,000 years BP; zone 3: 19,000 to 12,500 years BP; zone 2: 12,500 to 5,500 years BP; zone l: 5,500 years BP to top of core. Dinoflagellate cysts display a tropical assemblage wwith mostly estuarine neritic elements and also a weak oceanic component, mostly in the lower slope core 47. Cosmopolitan taxa dominate the assemblage and only a few species point to more specialized environments. Quantitative variations of the assemblage are the basis of stratigraphy which is not similar to the pollen stratigraphy, and an inshore-outshore gradient has to be taken into account to correlate the three cores.

Description: Surface sediments from 5 profiles between 30 and 3000 m water depth off W Africa (12-19° N) have been studied for their sand fraction composition and their total calcium carbonate and organic matter contents to evaluate the effect of climatic and hydrographic factors on actual sedimentation. On the shelf and upper slope (〈 500 m), currents prevent the deposition of significant amounts of finegrained material. The sediments forming here are characterized by high sand contents (〉 60 % ; in most samples 〉 80 %), low organic carbon contents (in most samples 〈 0.8 %), high median diameters of the sand fraction (120-500 μm), and by a predominance of quartz and biogenic relict shells (most abundant: molluscs and bryozoans) in the sand fraction. Median diameters of total sand fraction and of major biogenic sand fraction components (biogenic relict material, benthonic molluscs, benthonic and planktonic foraminifers) co-vary to some extent and show maximum values in 100-300 m water depth, reflecting the sorting effect of currents (perhaps the northward flowing undercurrent; MITTELSTAEDT 1976). In this water depth, biogenic relict material is considerably enriched relative to quartz, the second dominating sand fraction component on the shelf and upper slope, resulting in distinct calcium carbonate maxima of the bulk sediments. The influence of the undercurrent is also reflected in a northward transport of finegrained river load and perhaps in the distribution of the red stained, coarse silt and sand-sized clay aggregates, which show maxima in 300-500 m water depth. They probably originate from tropical soils. Abundant coarse red-stained quartz on the shelf off Cape Roxo (12-13° N) suggests a southward extension of last glacial dune fields to this latitude. Below about 500 m water depth, current influence becomes negligible - as indicated by a strong decrease in sand content, a concomitant increase in sedimentary organic carbon contents (up to 2.5-3.5 %), and the occurrence of high mica/quartz ratios in the sand fraction. Downslope transport, presumably due to the bioturbation mechanism proposed by BEIN & FüTTERER (1977), is indicated by the presence of coarse shelfborne particles (glauconite, relict shells) down to about 1000 m water depth. The fine/coarse ratio (clay + silt/sand) of the sediments from water depths 〉 500 m never exceeds a value of 11 in northern latitudes (19°-26° N), but shows distinct maxima, ranging from 50 to 120, at latitudes 18°, 17°, 15° 30', and 14° N in about 2000 m water depth. This distribution is attributed to the deposition of fine-grained river load at the continental slope between 18° and 14° N, brought into the sea by the Senegal and southern rivers and transported northward by the undercurrent. Strang calcium carbonate dissolution is indicated by the complete disappearance of pteropods (aragonite) and high fragmentation of planktonic foraminifers (calcite) in sediments from water depths 〉 300-600 m. Fragmentation ratios of planktonic foraminifers were found to depend on the organic carbon/carbonate ratio of the sediment suggesting that calcite dissolution at the sea bottom may also be significant in shelf and continental slope water depths if the organic matter/carbonate ratio of the surface sediment is high and the tests remain long enough within the oxidizing layer on top of the sulfate reduction zone. The fact that in the region under study intensity and annual duration of upwelling decrease from north to south is neither reflected in the composition of the sand fraction (i. e. radiolarian and fish debris contents, radiolarian/planktonic foraminiferal ratios, benthos/plankton ratios of foraminifers), nor in the sedimentary organic carbon distribution. On the contrary, these parameters even show in comparable water depths a tendency for highest values in the south, partly because primaty production rates remain high in the whole region, particularly on the shelf, due to the nutrient input by rivers in the south (SCHEMAINDA et al. 1975). In addition, several hydrographic, sedimentological and climatic factors severely affect their distribution - for example currents, dissolution, grain size composition, deposition of river load, and bulk sedimentation rates.

Description: The Baie du Lévrier (some 800 km2, 〈 20 m deep) lies at about 21° N. The climate is arid. Hydrographie conditions are controlled by (1) Trade winds, which largely determine wave base, (2) tidal currents, and (3) upwelling on the shelf nearby. Sediments range from carbonate-poor silty muds to carbonate-rich sands. Below wa ve base sediments characteristically have 〈 30% sand, sand medians 〈 125 μm and 55-80% silt, whereas wave-washed sediments have 〉 70% sand with medians 〉 400 μm. Other dynamic factors, notably tidal currents, may blur the distinction between these two populations. Sources for the terrigenous components are (1) modern aeolian dunes whose sands enter the sea to form a prograding coastal sediment wedge; (2) wind dust deposited as silty muds below wave base; (3) sub-Recent relict material on the seafloor; ( 4) cliff and bank erosion (local); (5) sea bed-load, significant in current-washed areas. Non-terrigenous components include pellets, ooids and skeletal debris. Pellets, incompletely indurated and mainly faecal, form up to 2/3 of the sand fraction in muds below wave base. Relict pellets are rare. Superficial ooids occur in trace quantities in some beach and nearshore samples. Skeletal debris accounts for most of the carbonate sand and also contributes significant quantities of biogenic opal and phosphatic material. Relict and mineralized (goethite and Fe-silicates) skeletal grains are locally important. Like the modern skeletals they are of foramol type. In the modern skeletal sand molluscan material is ubiquitous ( 〈 20% to 〉 90% of skeletal sand) but, as little can be identified further, molluscs as a whole have little interpretative value. Other skeletals form two groups: ( 1) typical of the banks and flanks of the bay, includes barnacles, worm tubes, calcareous red algae, bryozoans and alcyonarian spicules (the two lattcr tend to occur close to rather than on the banks and to lie below wave base rather than in the wave zone as the others do); (2) found in "basinal" sediments below wave base, includes calcarcous, opalinc and phosphatic forms: foraminifers (benthonic and planktonic), echinoderms, ostracodes, sponge spicules, diatoms (planktonic and benthonic) and fish remains. From the relationships between the bank and "basinal" groups five skeletal grain assemblages are recognized and shown to be related to sedimentary facies (ranging from carbonate-poor, silty mud facies with foraminifers, sponge spicules, diatoms and fish remains, to carbonate-rich sand facies characterized by bank group skeletals, particularly barnacles). Within some of the assemblages there are marked and systematic lateral shifts in relative importance of skeletal components. All these features can be interpreted in terms of source and transportability of the grains, some (e.g. barnacle) being moved principally as bed load, while others are carried in suspension. Laterally graded suspensions are proposed to explain the distribution of the components of the "basinal" group and also, near banks (or flanks), of alcyonarian spicules and bryozoans. Proximity to oceanic influences is expressed particularly in fine-grained "basinal" sediments by relative increase of echinoderms, ostracodes and molluscs (particularly Pinna needles) as well as of planktonic foraminifers and diatoms relative to benthonic ones. Significant regional environmental features are expressed in the sediments as follows: Aridity limits terrigenous sediments to a coastal wedge of dune-derived sands, aeolian dust in silty muds below wave base, and products of local cliff erosion. By precluding freshwater "dilution" it allows evaporation to increase salinity and a few ooids form. Combination of offshore upwelling and the Canary Current accounts for the presence of the foramol skeletal association in the tropics, and for the unusually high percentage of biogenic opal (up to 〉 12% of total sample), (cool-water) planktonic foraminifers (up to 〉 25% of total foraminifers), fish debris, and perhaps also of ostracodes. The general water temperature and salinity regime is such that the Baie du Lévrier lies in a critical position on or near the boundaries between major provinces of carbonate sedimentation both for skeletal (foramol, but chloralgal known 150 km to south) and non-skeletal components (normally pellet, but oolithaggregate locally reached).

Description: Geophysical and geological surveys by R.V. "Meteor" (1967, 1975, 1977) and R.V. "Vema" (1973) revealed new information on the seismic stratigraphy and geological evolution of the Mazagan Marginal Plateau. Fragments of a light-colored, mylonitic granite were recovered from the base of the escarpment and interpreted as slivers of foundered continental basement, pushed upwards along landward dipping thrust faults. The upbuilding of a 〉 2 km thick carbonate platform during (? pre-)Oxfordian to middle Cretaceous times kept pace with its fast subsidence (up to 80 m/m.y.). At the foot of the 27-38° steep escarpment we dredged an Oxfordian well sorted algal and foraminiferal limestone which is devoid of any terrigenous components and full of shallow-water organisms; it indicates an euphotic, sublittoral, perireefal environment. Upslope on the escarpment, we infer outcrops of middle Aptian to early Albian quartzose, calcareous and siliceous nanno claystones which reflect an outer shelf setting. Below the outer Mazagan Plateau, seismic evidence suggests that individual reefal bioherms continued to grow above a mid-Cretaceous unconformity, while the underlying carbonate platform subsided below wave base and was covered by Late Cretaceous pelagic sediments. A Paleogene (? Paleocene) and an Oligocene unconformity can be distinguished on seismic records and correlated to Cretaceous and Tertiary outcrops on the shelf off EI Jadida. Paleogene glauconitic marls and thin Neogene hemipelagic sediments top the plateau and represent a slope environment of deposition.

Description: Taxonomical study of the Bryozoa collected during the cruises of R. V. "Meteor" near the French coast (Atlantic and Channel) and the coastline of Mauritania. First indications of Arachnoidea annosciae n'HONDT and GERACI, 1976, Onychocella antiqua (BUSK, 1858) and Cribrilaria flabellifera (KIRKPATRICK, 1888) in the temperate region of the North Atlantic.

Description: A study of recent publications on ichthyoneuston of subtropical seas showed that this fauna is neither regionally nor seasonally uniform. Available material of abundant and characteristic species off Northwest Africa was re-examined under this aspect. This material was collected during five German expeditions (1967-1973) between 20° and 36° N and between the coast and 30° W. It includes 366 hauls that could be utilized for qualitative analysis; out of these 333 hauls yielded quantitative information. Based upon variation in geographical and hydrographical factors, distribution of sampling locations and zoogeographical considerations, the study area was divided into five subregions (two neritic and three oceanic), each represented by a different number of samples. A clear faunistic boundary appears between neritic and oceanic subregions. This boundary is related to water depth and distance from shore. It is sharp for neritic species. It is also sharp for mesopelagic fishes as they do not occur in water shallower than the slope, whereas oceanic-epipelagic taxa are less affected by this boundary. Latitudinal zonation is also evident as it is a function of hydrographic factors, especially temperature, probably showing seasonal variations. The latitudinal boundary is less pronounced than the neriticoceanic one; simplified it is assumed as running through the Canary Islands region. In all subregions, ichthyoneuston abundances appear to be highest during winter months. Maximum of abundance is produced by spawning that is restricted in many species to this season. The five most common species constituted more than 80% of the total catch during winter. Their proportion decreased to less than 60% in warmer months due to the immigration of less common (largely tropical) species and the mortality and ontogenetic emigration of animals born during winter. Seasonal differences in diversity did not prove significant as species number in ichthyoneuston catches is generally high. Seasonal trends are conspicuous for typical species only and are discussed. The northwest African current system probably causes considerable drift in ichthyoplankton. This raises the question as to how stocks survive despite drift of early life stages. This problem is discussed for characteristic taxa. Depending on the species, several mechanisms acting either singly or in combination are possible: 1. Adults of tropical neustonic forms actively migrate into the study area in summer, passive southward transport of early stages being a necessary condition for survival during other seasons. 2. Southward transport of species performing diurnal vertical migrations may, in certain areas, be reduced if such species reach the poleward undercurrent and remain in it during part of the day. 3. South of Cape Blanc, inshore eddies and the temporary surface countercurrent may permit a longer stay or return transport. This mechanism is probably effective for neritic euneustonic animals.

Description: This paper deals with the presence and distribution of Thecosomatous Pteropods in the Indian Ocean. 122 plankton-samples, taken by R.V. "Meteor" during the International Indian Ocean Expedition (IIOE) in 1964-65 were investigated. They contain a total number of about 45000 Thecosomata, belonging to 22 species and 5 families. Some species (e.g. Creseis acicula and Limacina inflata) are common in the entire area, others (e.g. Creseis chierchiae and Desmopterus gardinieri) show a quite distinct distribution. From several species only one single specimen was captured, others are completely lacking in the collection though they have been reported frequently from the same area by other expeditions. This may be due to seasonal variations and to the fact that to bathial tows were taken. In spite of these restrictions the extensive material from a relatively small area offers the possibility to compare specific and nonspecific features in related species and to question their taxonomic value.

Description: We present a plate kinematic evolution of the South Atlantic which is based largely on the determination of the equatorial fracture zone trends between the African and South American continental margins. Four main opening phases are dated by oceanic magnetic anomalies, notably MO, A34, and A13, and are correlated with volcanism and tectonic events on land around the South Atlantic Ocean. The Ceara and Sierra Leone rises are probably of oceanic origin and were created 80 m.y. ago or later in their present-day positions with respect to South America and Africa.

Description: This paper concerns the linear response of the ocean to forcing at a specified frequency and wave number in the absence of mean currents. It discusses the details of the forcing function, the general properties of the equations of motion, and possible simplifications of these equations. Two representations for the oceanic response to forcing are described in detail. One solution is in terms of the normal modes of the ocean. The vertical structure of these modes corresponds to that of the barotropic and baroclinic modes; their latitudinal structure corresponds to that of inertia‐gravity and Rossby waves. These waves are eigenfunctions of Laplace's tidal equations (LTE) with the frequency as eigenvalue. The description in terms of vertically standing modes is particularly useful if the forcing is nonlocal, because only these modes can propagate into undisturbed regions. The principal result is that it is extremely difficult for baroclinic (but not barotropic) disturbances to propagate horizontally away from a forced region. Instabilities of the Gulf Stream excite disturbances that are confined to the immediate neighborhood of the current; disturbances due to instabilities of equatorial currents do not propagate far latitudinally. A second representation of the oceanic response to forcing is in terms of vertically propagating, or vertically trapped, latitudinal modes. These modes are eigenfunctions of LTE with the equivalent depth h (not the frequency) as eigenvalue. Both positive and negative eigenvalues h are necessary for completeness. The modes with h 〉 0 consist of an infinite set of inertia‐gravity waves and a finite set of Rossby waves which either propagate vertically or form vertically standing modes. The latitudinally gravest modes are equatorially trapped and have been observed in the Atlantic and Pacific oceans. The modes with h 〈 0 are necessary to describe the oceanic response to nonresonant forcing. In the vertical this response attenuates with increasing distance from the forcing region. Because of the shallowness of the ocean the large eastward traveling atmospheric cyclones in mid‐latitudes and high latitudes force a response down to the ocean floor. Interaction with the bottom topography will result in smaller‐scale disturbances and will affect the frequency spectrum of the response when bottom‐trapped waves are excited.

Description: An intensive three-dimensional survey of the Antarctic Polar Front was made in the Drake Passage in March 1976. The front, which was imbedded within one of the high-velocity cores of the circumpolar current, is viewed as a water mass boundary demarking the northern extent of near-surface antarctic waters. Within the front, water masses are observed to intrude, one above the other, with characteristic vertical scales of 50–100 m. The intrusions are horizontally anisotropic, being elongated in the alongstream direction and constrained primarily to the upper 800 m of the front. The spatial and temporal persistence of the variability is examined through the analysis of continuous vertical profiles of horizontal velocity, temperature, salinity, and oxygen with discrete sampling of nutrients. Analysis of the velocity data showed the mean current flowing to the NNE with speeds of the order of 30–40 cm s−1 in the upper 600 m, with temporal variability over a 28-hour ‘yo-yo’ due primarily to internal gravity waves. The thermohaline variability was not internal wave induced but rather was associated with nearly isentropic advection of different water masses across the front. Cold fresh and warm salty intrusions did not conserve potential density, however, and double-diffusive transfers are strongly suggested as being crucial to an understanding of the dynamics of the intrusions. Applying a model (Joyce, 1977) for lateral mixing we estimate poleward temperature and salinity fluxes due to interleaving of 0.086°C cm s−1 and 0.069‰ cm s−1, respectively. If these values are typical, interleaving could play a significant role in large-scale balance of salt and, to a lesser extent, heat for the Southern Ocean.

Description: Oceanographic measurements by groups from the Federal Republic of Germany contributed mainly to the C-Scale Experiment (centered at 9° N, 23° W) and the Equatoria1 Experiment. In this paper the data are presented that were obtained from the moorings F 1 and F 2 in the C-area. After a short discussion of instrument problems, data processing and statistical analysis, the data are presented graphically as time series, progressive vector diagrams, frequency distributions and spectra of horizontal kinetic energy and of temperature variance.

Description: The results of measurements on currents and stratification obtained by FRV "Anton Dohrn" during the GATE-Equatorial Experiment are presented in graphical form. Remarks on data processing arid errors involved are made accordingly.

Description: We report, numerically and in graphical form, measured tritium concentrations from five hydrographic stations in the North Atlantic. Fairly homogeneous concentrations are observed in a surface layer typically 400 m deep. In the thermocline, concentrations decrease steadily down to the a σθ = 27.3 density horizon, and are more variable further down. The tritium in the lower part of the thermocline originates from the Subarctic Intermediate Water and the Mediterranean Water. There is a relative tritium maximum associated with the Mediterranean Water on the easternmost station of the section. In the deep water (σθ 〉 27.8), concentrations east of the Midatlantic Ridge are close to the limit of detection down to 2500 m, and undetectable further down, while west of the ridge tritium is found throughout the water column. The deep water tritium is associated with the deep-water advective cores of Arctic origin. The present tritium data can serve as northern boundary values in attempts to use tritium in studies of the North Atlantic main thermocline dynamics. The present data together with data from the literature point to a general division of the North Atlantic main thermocline into two layers separated by an isopycnal surface near σθ = 27.3.

Description: During the international "Overflow-Expedition" 1973 on R.V. "Meteor" oxygen concentrations in surface layers were measured in order to determine the oxygen gradients within the First two meters and to add some informations to the mechanisms of oxygen exchange at the air-sea interface. These investigations may be interesting also with regard to long-term-observations of the oxygen distribution in the Atlantic, especially the problem of the A.O.U. (apparent oxygen utilization) determination. To measure oxygen gradients a special sampler was built which is able to take water samples each 20 cm of the First 2 meters. These data were supplemented by further samples down to 150 m, taken by conventional water samplers, from which samples were also taken to measure N2/02-relations. By comparing these relations with theoretical relations in air-saturated water the influence of biological production and consumption on the oxygen contents in water could be estimated. A simple glass apparatus was built to extract gas from the water samples, and hereafter the N2/02-relations were determined by mass spectrometry. Most distributions of the oxygen anomaly show a negative oxygen balance which varies largely, probably due to strong mixing processes in the Iceland-Färö ridge area. The distribution of surface oxygen saturation values are of two different types. The values of the stations 260, 262 and 270 stem from mixed water and show homogeneous supersaturations, as can be found instantly when whitecaps appear. The values of 9 other stations are from water, sampled during calm periods which has been mixed and supersaturated before. They show a decreasing oxygen saturation towards the sea surface and often undersaturation in the upper decimeters up to 98% and even 91%. So at the air-sea interface even less initial oxygen saturation than 100% can be found after supersaturation during heavy weather periods.

Description: Records of currents and temperature on the upper edge of the continental slope off Sierra Leone show a significant energy peak between 0.3 and 2 cph in the bottom near layer. The fluctuations of temperature and velocity are interpreted as internal waves over a critical bottom slope. Since they seem to receive their energy mainly from the barotropic tide, the phenomenon is of interest in the dissipation cascade of tidal waves. The high frequency current amplitudes are occasionally strong enough to affect sediment deposition and related benthic processes. Inspection of current meter records from other regions of the NW-African continental slope reveal the similar effect of intensified bottom current fluctuations.

Description: This paper presents a compilation of the data sets obtained by CTDs and profiling current meters on board the ships "Meteor" and "Planet" during GATE in the B- and C-Scale Areas (7°-10 °N, 22°-25°W, June 17 to September 24, 1974). The bulk of the CTD data is displayed in the form of isopleths. Selected sets of profiles, outlining special phenomena observed, and profiles of the mean and standard deviation of temperature and salinity are given additionally. Besides examples of actual current profiles, isopleths of the 25 hour mean current components, and isopleths of the vertical shear are presented. The mean current components and their standard deviations are also displayed. Time series presented are suitable for comparison with moored current measurements. The presentation of the data is preceded by a summary of the editing procedures and by a discussion of the data quality.

Description: One main point of our atmospheric-electric measurements over the Atlantic Ocean 1973 was the investigation of the air-earth current density above the sea. In addition to direct measurements at the water surface with a floating net, we calculated the air-earth current density from the electric field and the air conductivity measured simultaneously on board of the ship and during particular ascents in the free atmosphere. During all five ascents the air-earth current density did not change with altitude. For pure maritime air-conditions, the mean air-earth current density was found to be 2.9 pA/m2. The mean hourly air-earth current density over the Atlantic shows nearly the same 24-hour pattern as measured by COBB (1977) at the South Pole at the same time. When dust-loaden air masses of African origin reached the ship as well as under continental influence the mean air-earth current density was reduced to 2.1pA/m2. The global 24-hour pattern was modified by this continental influences. Finally, it is shown that the values of the air conductivity measured on board R. V. "Meteor" during our earlier expeditions have been influenced by the exhaust of the ship and must therefore be corrected. With this correction, our new mean values of the air-earth current density over the Atlantic are 2.6 pA/m2 in 1965 and 2.0 pA/m2 in 1969. From all measurements, the global air-earth current is estimated to be about 1250 A.

Description: The fluxes of momentum, heat, and water vapour have been obtained by the aerodynamic profile method. Within the frame work of GATE variation of fluxes with disturbed conditions are of special interest. The time traces of surface layer parameters repeatedly showed definite instationarities marked by a sudden drop of temperature by a few degrees centigrade. For these pronounced instationarities, equilibrium state of the profiles was regained after a few minutes, in agreement with scale considerations. For fluxes properly nondimensionalized in terms of surface layer parameters, no systematic deviations have been found under disturbed conditions compared with undisturbed conditions. Due to systematic variations of parameters, the energy exchange between sea and atmosphere was enhanced by about 30 % under disturbed conditions. From the above evidence it is concluded that for larger scale investigations reliable determination of fluxes from surface layer mean variables is possible.

Description: The Aitken particle size distribution in background aerosols was measured with a newly developed Diffusion Analyzer System. The measuring system and the inversion method is discussed critically. The several hundreds of measurements indicate that several maxima in the size distribution are present. Particles as small as 10-3 µm in radius are constantly observed. Measurements of other authors indicate similar results.

Description: Size distributions of Aitken nuclei were measured in the middle and western part of the North Atlantic between 38 through 22° N and 36 through 63° W. The apparatus comprised diffusion batteries and an especially designed condensation nuclei counter. The measurements cover the size range from about 3·10-1 through to 1·10-5 cm aerodynamically equivalent particle radius. There are some indications on the trend of particle numbers above 1·10-5 cm but no reliable number distributions. The size spectra were bimodal in the north eastern part of the cruise. Closer to the Caribbean the contribution of very small particles was enhanced and the peaks shifted to larger sizes to a certain extent.

Description: On board of the German research vessels "Meteor" and "Anton Dohrn" the components of shortwave and longwave radiation budgets have been measured over the Fladenground area during a short period in 1975 (13.-19. August) and the Fladenground-Experiment (FLEX, 25 March 1976-13 June 1976). The data show that in spring and in the beginning of summer, when the ocean water is still cool, the daily incident solar radiation exceeds the net thermal radiation loss of the water to the atmosphere. In August, however, the water emission has increased to such a level that on disturbed days the daily mean radiation balance is negative. The monthly averages of the radiation budget and the global radiation derived from the shipborn measurements agree surprisingly well with those derived by several authors from climatological data. A simple scheme has been developed to parameterize the global radiation with respect to the observed cloudiness.

Description: The Th content of the sediment samples from "Meteor" core 12310 (3080 m water depth, off NW Africa) on a carbonate-free basis lies around the average of 12.4 ppm and is similar to the average content of the earth crust. On the contrary, uranium was found to be up to 3.5-fold enriched in the core section between 60 and 330 cm (within the Würm Glacial) where reducing conditions occur, due to deposition of authigenic uranium (9 µg/cm2 1000 yrs.). The authigenic uranium content is correlated to the organic matter content (U/Corg ratio = 6 · 10-4). On the basis of the uranium content of the oxidized section uranium was split into a detritic and an authigenic component and the amount of supported ionium was calculated. From the profile of the specific I0.excess act1v1ty Io-total - Io-supported) with depth, average sedimentation rates of 3.3 ± 0.6 cm/1000 yrs. for the warmer stages and of 5 ± 1 cm/1000 yrs. for the cooler periods were estimated.

Description: A rapid procedure for Io (Th230) dating of sediments with accumulation rates in the range of several cm/1000 years is described. Studying of large sample populations with very small Io-excess activity is possible as the counting time (around 1500 min/sample) are 2 to 5 times shorter than with the standard Io-excess method. Improved sensitivity of the Io-excess measurement is achieved by: 1) extraction (~90%) of the authigenic Io-excess with EDTA, with minor leaching (~30%) of the allogenic Th232 and Io-supported, 2) processing samples as large as 10 g or more. The procedure was applied to sediments from the Caribbean (V 12-122) and from the Ionian Sea (22M48 and 17M17). In the case of the standard core V 12-122 our results are in good agreement with previous time-consuming Io determinations. The resulting average accumulation rates of 2.0 ± 0.3 cm/1000 years for the Ionian Sea cores are close to the average derived from magnetic reversal studies of a nearby core.

Description: A preliminary study was carried out on the ostracode fauna obtained from marine sediments off the Sahara Desert. The ostracodes are divided into two distinct associations: Association A - shallow water (100-483 m); Association B - deep water (470-2859 m). The deep water association differs from that of the shallow water by its low diversity and by the predominance of somewhat larger "blind" ostracodes in it. The depth of the boundary between the two associations corresponds closely to the general universally recognized 500 m boundary, below which psychrospheric conditions prevail and dictate the appearance of typical deepwater ostracode fauna.

Description: Deep‐sea drilling in the Antarctic region (Deep‐Sea Drilling Project legs 28, 29, 35, and 36) has provided many new data about the development of circum‐Antarctic circulation and the closely related glacial evolution of Antarctica. The Antarctic continent has been in a high‐latitude position since the middle to late Mesozoic. Glaciation commenced much later, in the middle Tertiary, demonstrating that near‐polar position is not sufficient for glacial development. Instead, continental glaciation developed as the present‐day Southern Ocean circulation system became established when obstructing land masses moved aside. During the Paleocene (t = ∼65 to 55 m.y. ago), Australia and Antarctica were joined. In the early Eocene (t = ∼55 m.y. ago), Australia began to drift northward from Antarctica, forming an ocean, although circum‐Antarctic flow was blocked by the continental South Tasman Rise and Tasmania. During the Eocene (t = 55 to 38 m.y. ago) the Southern Ocean was relatively warm and the continent largely nonglaciated. Cool temperate vegetation existed in some regions. By the late Eocene (t = ∼39 m.y. ago) a shallow water connection had developed between the southern Indian and Pacific oceans over the South Tasman Rise. The first major climatic‐glacial threshold was crossed 38 m.y. ago near the Eocene‐Oligocene boundary, when substantial Antarctic sea ice began to form. This resulted in a rapid temperature drop in bottom waters of about 5°C and a major crisis in deep‐sea faunas. Thermohaline oceanic circulation was initiated at this time much like that of the present day. The resulting change in climatic regime increased bottom water activity over wide areas of the deep ocean basins, creating much sediment erosion, especially in western parts of oceans. A major (∼2000 m) and apparently rapid deepening also occurred in the calcium carbonate compensation depth (CCD). This climatic threshold was crossed as a result of the gradual isolation of Antarctica from Australia and perhaps the opening of the Drake Passage. During the Oligocene (t = 38 to 22 m.y. ago), widespread glaciation probably occurred throughout Antarctica, although no ice cap existed. By the middle to late Oligocene (t = ∼30 to 25 m.y. ago), deep‐seated circum‐Antarctic flow had developed south of the South Tasman Rise, as this had separated sufficiently from Victoria Land, Antarctica. Major reorganization resulted in southern hemisphere deep‐sea sediment distribution patterns. The next principal climatic threshold was crossed during the middle Miocene (t = 14 to 11 m.y. ago) when the Antarctic ice cap formed. This occurred at about the time of closure of the Australian‐Indonesian deep‐sea passage. During the early Miocene, calcareous biogenic sediments began to be displaced northward by siliceous biogenic sediments with higher rates of sedimentation reflecting the beginning of circulation related to the development of the Antarctic Convergence. Since the middle Miocene the East Antarctic ice cap has remained a semipermanent feature exhibiting some changes in volume. The most important of these occurred during the latest Miocene (t = ∼5 m.y. ago) when ice volumes increased beyond those of the present day. This event was related to global climatic cooling, a rapid northward movement of about 300 km of the Antarctic Convergence, and a eustatic sea level drop that may have been partly responsible for the isolation of the Mediterranean basin. Northern hemisphere ice sheet development began about 2.5–3 m.y. ago, representing the next major global climatic threshold, and was followed by the well‐known major oscillations in northern ice sheets. In the Southern Ocean the Quaternary marks a peak in activity of oceanic circulation as reflected by widespread deep‐sea erosion, very high biogenic productivity at the Antarctic Convergence and resulting high rates of biogenic sedimentation, and maximum northward distribution of ice‐rafted debris.

Description: A model for earthquake swarms in volcanic regions consists of the following concepts: (1) clusters of magma‐filled dikes exist within brittle volumes of the crust, (2) dikes within a cluster are systematically oriented with their long dimension in the direction of the regional greatest principal stress, and (3) a sequence of shear failures (an earthquake swarm) occurs along a system of conjugate fault planes joining en echelon offset dike tips at oblique angles. This model accounts for commonly observed geometric relations between surface faulting patterns, the hypocentral distribution of swarm earthquakes, and fault plane solutions in a variety of situations. Swarm areas dominated by strike‐slip faulting, however, provide the most compelling examples of the utility of the model. Specific examples considered here include a swarm on the east rift zone of Kilauea volcano, Hawaii, and swarms in the Imperial Valley, California, and the Reykjanes Peninsula, Iceland, which represent transitional zones between spreading centers and transform faults.

Description: The distribution of 210Pb and 210Po in dissolved ( 〈 0.4-micron) and particulate (〉 0.4-micron) phases has been measured at ten stations occupied during cruise 32 of F. S. "Meteor" in the tropical and eastern North Atlantic. Both radionuclides occur principally in the dissolved phase. Unsupported 210Pb activities, maintained by flux from the atmosphere, are present in the surface mixed layer and penetrate into the thermocline to depths of about 500 m. Dissolved 210Po is ordinarily present in the mixed layer at less than equilibrium concentrations, suggesting rapid biological removal of this nuclide. Particulate matter is enriched in 210Po, with 210Po/210Pb activity ratios greater than 1.0, similar to those reported for phytoplankton. At depths of 100-300m, 210Po maxima occur, and unsupported 210Po is frequently present, an observation that suggests rapid re-cycling within the thermocline. Comparison of the 210Pb distributions with those reported for 226Ra at nearby GEOSECS stations confirms the widespread existence of a 210Pb/226Ra disequilibrium in the deep sea. Close to the bottom, profiles of 210Pb and 226Ra usually diverge, and 210Pb concentrations frequently decrease with depth, suggesting a sink for 210Pb near the seafloor. Particulate 210Pb concentrations ordinarily show little systematic variation with depth. At depths greater than 1,000 m, dissolved 210Po activities are, on the average, less than those of 210Pb by 12 % . A corresponding 210Po enrichment in the particulate phase is found.

Description: Pelagic tar has been collected daily on a transsect from off Prtugal to south of the Canary Islands in January/February 1975. A new neuston sampler was used which may be towed at speeds between 7 and 10 knots (DERENBACH & EHRHARDT 1975). A total of 22 samples was taken. Dimensions of tar balls ranged from potatoe-size to small specks approximately 1 mm in diameter. Concentrations were found to vary between 20.5 and 0.007 mg/m2, except for one instance of an extremely high tar concentration of 2270 mg/m2. 49 GC analyses were made. 61% showed bimodal peak distributions characteristic of crude oil sludges. The composition of tar balls was independent of their size suggesting diffusion controlled degradation.

Description: During the International ICES Expedition "Overflow '73" a total of 174 samples from 18 stations were collected by R. V. "Meteor" in the waters of the Iceland-Faroe Ridge area. They were filtered on board ship (through 0.4 µm "Nuclepore" filters), then stored in 500 cm3 quartz bottles (at -20°C) and analyzed in air-filtered laboratories on land for zinc and cadmium by means of the differential pulse anodic stripping voltammetry technique and copper and iron by flameless atomic absorption spectrometry. The overall averages of 1.9 µg Zn l-1, 0.07 µg Cd l-1, 0.5 µg Cu l-1 and 0.9 µg Fe l-1 are in good agreement with recent "baseline" studies of open-ocean waters. The mixture of low salinity water masses from the North Iceland Shelf/Arctic Intermediate Waters seem to maintain distinctly lower concentration of Cd, Cu and Fe than the waters from the North Atlantic and the Norwegian Sea where quite similar mean values are found. There is only little evidence for the assumption that overflow events on the ridge are influencing the concentrations of dissolved metals in the near-bottom layers.

Description: The hydrodynamic roughness of the sea surface at low wind speeds (u10 〈 5 ms-1) is investigated according to the aerodynamic profile method. The wind, temperature, and humidity profiles were measured during GATE in 1974. In some earlier publications on this subject the density stratification has not been considered. Therefore apparent roughness parameters are found, which are smaller than those for a hydrodynamic smooth flow. In this paper the density stratification was determined from 10 m-values of wind, temperature, and humidity. From more than 1 OOO 10 min-profiles an average drag coefficient reduced to neutral stability of CD,N10 = (1.10 ± 0.32) · 10-3 for u10 〈 5 ms-1 is obtained. As the slight decrease of CD,NlO with increasing wind speed is not significant, CD,NlO can be regarded as independent of the wind speed. In the range of low wind speeds (1.75 ms-1 〈 t110 〈 5 ms-1) the sea surface is hydrodynamically rough. The validity of the Charnock formula z0 = u*2/ag cannot be verified. An influence of wind waves on the wind profile can be shown even for wave heights less than 0.75 m up to a level of 2 m above the sea surface. Therefore the drag coefficient was determined from wind values above 2 m height.

Description: During GATE 37 flights with radiometersondes to measure the infrared radiation were made from R.V. "Meteor" at 7.8° N, 22.1° W. This position was close to the ITCZ, very often high reaching convective clouds dominated. The profiles of the irradiances are dominating influenced by clouds. Examples are given, one showing the dependence on cirrus clouds, another that on dense altostratus and nimbostratus clouds. The goal of the measurements was to obtain mean profiles of infrared radiative heating rates, but due to the high variability of the clouds and due to the difficulty to assign the flights to distinct clouds, only three mean profiles could be calculated: - Average of all 37 flights, - Clear skies, - Skies overcast with medium clouds.

Description: The net flux of all irreversible fluxes of radiation and heat crossing the ocean surface is determined for phase III of GATE at position no. 27 (WFS "Planet", FRG). The radiation fluxes have been measured directly, while the heat fluxes have been parameterized with the bulk formula however with bulk coefficients depending on stability. The heat loss of the ocean due to warming of the cooler precipitation is included for the determination of the net flux at the ocean surface. Some examples of hourly mean values of different fluxes during different weather conditions are additionally shown.

Description: Spectral analysis of time series for hourly and three minutes surface observations of potential temperature, specific humidity and wind speed show significant differences between spectra for disturbed and undisturbed conditions in the period range between one and five days and 30 and 120 minutes. The spectrum of pot. temperature which was found to be a good indicator of convective activity showed that these differences are mainly caused by enhanced convection during disturbed conditions, as the cloud and subcloud layer are strongly coupled by updrafts and downdrafts. This convective mixing influences the near surface fields of pot. temperature, wind velocity, and to a lesser extent 0£ specific humidity. For moderate to depressed convection the cloud and subcloud layers are less coupled. The diurnal radiative forcing then determines the spectra. Convection seems not to be distinctly organized, while during enhanced convective activity, the individual clouds are organized on a larger scale, forming what is commonly called cloud clusters. Two modes are found in the long period range which could be determined with a certain significance. The first one in the range of 4 to 5 days the second one in the range of 30 to 40 hours. The analysis of the high resolution buoy measurements at "Meteor" shows a further maximum due to convective influences for periods of about 40 minutes.

Description: With a 6-channel integrating nephelometer spectral scattering properties of the atmospheric aerosol have been measured during the third part of the Atlantic Expedition 1969. A meridional cross section of light scattering integrals in the wavelength range 0.475 µm to 0.924 µm was recorded reaching from 10° S to 60° N along 30° W. With a new algorithm the time series of hourly scattering spectra was inverted yielding a first meridional cross section of the median radius of the number size distribution in situ. Three air mass regimes could be distinguished in the course of the experiment, the first one being the extremely clean air of the SE-trade south of the ITC. An abrupt increase in light scattering marked the hemispheric change when the ship entered the NE-trade which was heavily loaded with Sahara dust. North of the trade region the ship sailed through maritime North Atlantic air masses with highly variable light scattering and a slow decrease in median radius with latitude.

Description: Sediment cores from the continental slope off NW Africa (20-27° N) have been investigated by means of an analysis of clay minerals, of grajn size distribution of terrigenous material and of coarse fractions and CaC03 -contents. Deductions concerning Late Quaternary climatic variations could be made from the obtained results. The interglacial periods X and Z (stage 1 and 5 after SHACKLETON & OPDYKE 1973) had an arid climate, characterized by: a) presence of chlorite and attapulgite in noticeable amounts, these fragile minerals being preserved from weathering in dry climatic conditions, b) small grain size of terrigenous material, c) high desert quartz numbers, high CaC03-amounts of total sediment, small terrigenous input and low transport energy. The glacial periods Y and W (stage 2-4 and 6) had a humid climate. This is suggested by: a) the absence or rareness of chlorite and attapulgite and increasing amounts of mixed-layer minerals, b) high amounts of coarse-grained terrigenous material, indicating greater transport energy, c) low or disappearing desert quartz numbers, low CaC03-content and high terrigenous input. The cores from 27 and 20° N do not fit into this general scheme, because they are situated at climatic boundaries, the northern core lying at the actual boundary of mediterranean humid and arid climate, the southern core lying at the Würm boundary between humid and arid climate. Results of 40-63 μm sized desert quartz and amount of 〈6 respectively 20-63 μm fraction show sharp boundaries between stratigraphic zones, revealing rapid changes in climate. Clay mineralogical changes are less rapid, showing the progressive changes in soil formation and soil destruction. The origin of the clay minerals is exclusively detrital. Their quantitative variations show a differential settling with distance from coast, and a latitudinal zonation parallel to terrestrial soils.

Description: The 60 km wide shelf off Mauritania is cut by several submarine canyons. Its water-circulation is controlled by the cool Canary current and upwelling. Its Recent sediments show faunal assodations remarkably related to the grain size distribution which in water depths between 40 and 80 m is strongly influenced by reworldng of older coarse sand or sandstone. In this depth range a mixed biofades originating from Pleistocene and Recent material is encountered. The present lateral faunistic and sedimentological fades change, including horizons of mixed provenance, can be recognized in vertical sequences taken by vibro-coring. This correlation combined with 14C-datations on molluscs enable the reconstruction of the history of the last gladal regression and transgression. Due to the arid climate, the emerging calcareous shelf sediments are indurated and, therefore, protected from subaerial and submarine erosion. During low sea level eolian sand migrates over the shelf, but only about l/10 of this material remains there and is later incorporated into the sandy shelf sediments. The calculated average rate of total sedimentation during Holocene is 15 cm, and the production rate of carbonate is 5 cm/1000 years.

Description: In March 1974 combined refractional and reflectional seismic experiments were performed in the Cretan Sea. A total of 141 shots were fired along two lines, one parallel to the main structure striking nearly E-W between Karpathos and the SE-Peloponnese, the other perpendicular to it between Crete and Santorin (Thira). The shots were observed at 13 sites on land and by four buoy stations at sea. The seismic data reduced to time-distance plots and evaluated by direct and inverse ray theory methods revealed that: The Cretan Sea builds an E-W elongated dome of the upper mantle with maximum crustal attenuation at its central part and a thickness of nearly 20km. The vertical distribution of the P wave velocity is that of a continental crust that has been subjected to attenuation. The present distribution of sediments is mainly confined to the zone: SE-Peloponnese-Kithera-Antikithera-Crete-Karpathos, and also to small depressions within the central basin. In general they do not exceed 2 km in thickness. The uneven distribution of the sediments indicates the possibility of a two phase subsidence of the Cretan Sea. Areas with no or very thin sedimentary cover belong to the youngest tectonic phase. The morphology of the crystalline basement has been formed by intensive fragmentation, consisting mainly of normal faults, typical for tensional tectonism. The northern border of the Cretan Sea exhibits intensive volcanism along the line : Methana-Milos-Santorin-los. This zone is partly mobilized and intruded by surplus masses from the upper mantle as shown in the case of Santorin.

Description: This paper is a dcscription of the shallow structure of the Cretan Trough in the Aegean Sea as illustrated by continuous seismic profiles obtained by R. V. "Meteor" (1600 n.m., 1974), and R. R. S. "Shackleton" (1000 n.m., 1972, 1974). Study of this data shows an erosional unconformity between indurated rocks and sediments which over most of the Cretan Trough corresponds to erosion after the main Alpine orogeny and prior to the Upper Tortonian and in some places to the Upper Pliocene transgression. Thick sediments of up to 1.5 km have collected in local basins. Strong vertical movements on normal faults were responsible for the formation of the Cretan Trough and subsequently controlled the sedimentation. Sediments within the Trough have been deformed by Upper Pliocene/Pleistocene faulting and folding. Quaternary intrusions of volcanic? material are sporadically observed over the whole width of the Cretan Trough and do not suggest active seafloor spreading. Extensional processes are seen to be the dominant f eature in the tectonics of this area since ca. 10 m. y. A geodynamic process responsible for the observed structural data - mantle diapirism or subduction induced back-arc spreading - could not be derived from the reflection seismic data.

Description: Sediments sampled in three lateral traverses from the outer continental shelf to the continental rise off the Sahara Desert were analysed for their grain size distribution and composition. The carbonate content of the shelf and upper slope sediments increases from about 10-15 % in the south to about 50-90 % in the north and changes to about 40-45 % in deeper water. The high carbonate content in the north generally reflects the high proportion of relict material in the sediments. The main change in the composition of the sediments - defined mostly as hemipelagic - from the outer shelf to the rise is in an increase of coccoliths and clays and a decrease of quartz. The cumulative grain size curves indicate that each of the samples is a mixture of different proportions of two approximately log normal populations. The size of the truncation point between the populations, the proportion between the coarse and fine populations and the mean, sorting, skewness and kurtosis decrease with increasing depth. Correlations between the parameters indicate that the moments express mainly the mixture proportions of the two populations. The two populations may, however, indicate an artificial effect of deflocculation during sample treatment rather than reflecting some hydraulic factor. The cumulative grain size distribution curves of eolian dust collected on ship's surface during cruises along the Saharan shelf and that of other published data is divided into a two-population and a onepopulation type. The two populations may be attributed to either gravitational settling of larger dust particles and normal dust fall or to disaggregation effect. The moment statistics of the dust differ mainly from those of the marine sediments in that they have a lower standard deviation. The composition and the textural parameters, combined with modal analysis of the dust and the separated soluble and insoluble components of the sediments indicate that the downslope transportation of the coarser sediment particles is a result of marine currents rather than of wind. The distribution pattern of the relict material in the northern outer shelf and upper slope is attributed to an extinct current regime which was stronger than the present one. The gravitational settling of coarse dust, mainly over the shelf, most probably accounts for the principal input of sediment that is transported further downslope by marine currents. Part of the fine, as well as a small portion of the coarse terrigenous material may be derived from direct settling of dust over the open sea. The recent sedimentation process results in a continental margin prograding off the Sahara Desert. In the south sedimentation occurs on the outer shelf, slope and rise, whereas in the north main sedimentation occurs on the lower slope and rise. The deflection of the Canary current away from the Cape Blanc coast is proposed as an explanation for the apparent reduced deposition rate over the outer shelf and upper slope in the northern area.

Description: Light and electron microscopic examination of a number of dpecies previously attributed to the genus Syracosphaera LOHMANN show that three groups can be delimited, all of which warrant generic status. Caneosphaera GAARDER and Coronosphaera GAARDER are described, and the genus Syracosphaera with type species the two-layered S. pulchra LOHMANN is emended with redescription in terms of morphological features seen under light and electron microscope. New combinations are presented for five species.

Description: Through correspondence, the authors determined that each possessed material of an undescribed wrasse of the genus Suezichthys SMITH. The first five specimens of this species were taken in December, 1964 by R. V. "Anton Bruun" while trawling in 78-82 m and in 70-80 m (2 and 3 specimens resp.) off the Somali Republic, East Africa; the next two were collected a month later by R. V. "Meteor" by trawl off Kenya in 124-130 m; the last two were trawled in July and October, 1972 by U. S. National Marine Fisheries Service research vessel "Townsend Cromwell" off Oahu, Hawaiian Islands in 119-168 m. These nine specimens form the basis for the description herein of this new labrid fish.

Description: 46 hydropolyp species of 28 genera and 10 families were sampled during the "Meteor" passage 1964/65 (IIOE) through the Red Sea and its northern and southern exits and on the occasion of several ecological investigations of 29 selected coral reef sections of the central Red Sea and the Gulf of Aqaba. These collections comprise 128 single records of hydropolyp species. Three species and two genera each with one species are doubtful. 25 species, seven genera, one family and one subfamily, together from 49 records have not previously been found in the Red Sea and its exits. Including these newly reported species, the total list increases from 64 species and 112 records (SCHMIDT 1972) to 89 species and 240 single records and 51 additional ones. Scanning microscopical photos, made for the first time for the illustration of the hydropolyps, have been shown to be suitable for a better characterization and diagnosis of the species. Qualified results on the reasons for the horizontal distribution of the species known from the Red Sea area cannot be given because of the low number of samples sporadically distributed through the whole area. In contrast with this fact, the vertical spread of the species sampled seems primarily to be regulated by water exchange and light intensity. For example, four species of hydropolyps are excellent indicators of certain abiotic factors or combinations of them: Gymnangium eximium reacts extremely stenophote-photophobe-rheophil, Eudendrium ramosum moderately stenophote-photophobe-rheophobe, Lytocmpus philippinus moderately stenophotephotophil-rheophil, and Halocordyle disticha var. australis extremely stenophote-photophil but moderately rheophil. Other species have been found throughout all the light zones. Combined with the small size of their colonies their euryphotic behaviour does not allow their use as indicator species.

Description: Four species of gammaridean Amphipoda are recorded from the Iberian deep sea basin at about 5000 m depth: Bathyceradocus iberiensis sp. n., Paracallisoma platepistomum sp. n., Parandaniexis cf. mirabilis SCHRELLENBERG, 1929, and Parargissa galatheae BARNARD, 1961. The biogeography of the four species is discussed.

Description: Using a Bongo-Net equipped with a multiple codend closing device, the vertical distribution of siphonophores has been observed in 100 m depth intervals at 13 stations off Cap Mirik (19° N) (from 0-500 m depth). The distributional pattern of the 15 siphonophores species found is discussed in relationship to the hydrography of this upwelling region. The following main features have been observed in comparison with the warmer oceanic water offshore: (1) a lower diversity, (2) a shallower distribution of some of the deep living species due to the lower temperature in the upper 300 m and a lower transparency, (3) no contribution to acoustic scattering by physonect siphonophores.

Description: From sublittoral silty sediments (118 m depth) of the North Sea (59° 0.5' N; 01° 20.5' E), Bathymacrostomum spirale n. gen. n. sp. is described on the basis of squeeze preparation. According to the organization of the cuticular apparatus of the bursal organ the species belongs to the family Dolichomacrostomidae RIEGER, 1971. The absence of an accessory gland organ and the simplicity of the penis stilet leads to the establishment of the subfamily Bathymacrostominae nov. subfam.

Description: Description of Acanthophmyngoides quintus nov. spec. (Desmodorinae) with discussion of the systematical relationship to Spiriniinae and Pseudonchinae, and description of Richtersia iberica nov. spec. with discussion of the relationship to Desmodorinae.

Description: The Great Meteor Seamount is situated in the subtropical NE Atlantic. The dimension of the plateau in the depth of 400m is 1465 km2 ; its lowest depth 275 m. 35 species have been caught above the plateau in 1967 and 1970 (voyages 9 c and 19; R. V. "Meteor") with a bottom trawl, the Agassiz-trawl, with BEYER's epibenthic closing net, the triangle-dredge and the chain-dredge. For comparison fishes of the same species were collected off Morocco, Mauretania and Senegal. The circular current system above the seamount and the low rates of the net transport are the reasons for the existence of the autochthonous demersal fish populations, in spite of the pelagic stages of development. A comparison of the populations of three species from the seamount and from the African shelf, using a multivariate method (linear discriminant function), indicates a genetical diverging development of the populations. An overlapping of the populations is only applicable for 1.7 % of the individuals. This argument for an autochthonus demersal fish fauna is corroborated by nearly the same composition of species in 1967 and 1970, the small differences in the dominance of the species and the great homogeneity of the fish fauna in the two years. The distribution of the species above the plateau is nearly uniform. The species Aulopus filamentosus, Phycis phycis, Macroramphosus scolopax, Anthias anthias, Antigonia capros, Capros aper, Callionymus phaeton and Arnoglossus rueppelli are characteristic for the fauna, as in 6 of 11 comparable catches these 8 species were present together. For the demersal fishes the plateau is a rather uniform biotope, for it is mainly covered with biogenic sand. The aggregations of the seamount's own plankton and nekton near the bottom in daytime is exclusively or partly the food for 94% of the fish species, while the bottom fauna is only utilized by 22% of the species. Only Callionymus phaeton feeds exclusively on bottom animals. Shrimps (predominantly Plesionika heterocarpus) are the favoured prey of the majority of fish species. Relative to the number of examined stomachs the small crustacea like ostracodes and copepods are most abundant. Fishes were found in the stomachs of 8 species. Moreover cuttle-fish are of some importance as food of the bigger fishes. A comparison of the food of respective species from the African shelf shows that the lower availability of food above the seamount has no influence on the feeding behaviour of the species. lt seems, that there is sufficient food at the seamount, so that the fishes must not put up with animals they disdain elsewhere. The fish fauna from the Great Meteor Seamount shows the greatest similarity with the demersal fish fauna of the African shelf between Gibraltar and Cap Blanc (28 species in common). The Great Meteor Seamount has only 24 species in common with Madeira and 17 with the Canary Islands. Two species suggest a possible influence of settlement from the Western Atlantic. These species also belong to the fauna of Madeira and the Josephine Seamount, while they are absent on the African shelf. The species Gnathophis codoniphorus, Callionymus sousai and probably also the ray of the genus Raja are endemic. The depth of the plateau (275-400 m) has a great influence on the composition of the fish fauna. Regarding the vertical distribution of the species in the rest of their distribution areas, the plateau of the Great Meteor Seamount is situated at the optimal depth.

Description: 85 species of polychaetes were collected, 72 of them were determined to species level. One genus (Palposyllis n. g.), four species (Pionosyllis gorringensis n. sp., Palposyllis prosostoma n. sp., Potamethus filiformis n. sp., Potamethus breviuncatus n. sp.), and one subspecies (Ophelina delapidans longicephala n. subsp.) were described as new taxa. The majority of the species collected during this cruise have their distribution in the Atlantic Ocean or are more widely distributed. Peisidice bermudensis was found the second time after its original description. Lepidastenia brunnea and Isolda whydahensis never have been found as far north off the coast of Portugal. The interstitial living species Pisione remota and Hesionides arenaria, usually common in shallow waters, were found in deeper water (72 m and 120-180 m) for the first time.

Description: Off the NW-African coast in February 1973 neuston was sampled between latitudes 36° and 30° N as part of the CINECA multiship survey. The ichthyoplankton, fish larvae only, of these neuston samples was investigated under qualitative and quantitative aspects. Due to winterly environmental conditions and a more northern station-grid compared to the other "Meteor" expeditions, the total yield was low, for subtropical faunistic elements were absent or less abundant. The northern neritic part showed densities of only 3.0 fishes/100 m3 of water filtered, in the southern neritic zone maximum values occurred with 18.9 animals/100 m3, but even these values were far lower than those found in winter 1970, when surfacetemperatures and the amount of subtropical species were higher. The investigated area is considered to be a transitional zone between boreal and subtropical conditions under regional and seasonal aspects. For the most frequent taxa earlier findings on zoogeography, behaviour and ecology could be confirmed and completed.

Description: The report considers all planktonic stages of the Mysidacea Lophogastrida, Amphionidacea and Decapoda taken by R.V. "Meteor" in plankton samples over Josephine and Great Meteor Seamounts and regions of similar latitude off the Portuguese and Moroccan coasts. Larvae of most species in the vicinity of the seamounts were virtually confined to the upper 100 m. Circadian vertical migration was not evident. The waters over the seamounts were not avoided by holopelagic species. Such waters yielded fewer species of meroplanktonic larvae than the coastal regions and showed few species in common with each other or with the coastal regions. One larval species from both seamounts and three from Great Meteor Seamount show major characters unknown in larvae from European or North African waters.

Description: Published geological and geophysical data are reviewed. The Walvis Ridge is a complex linear feature made up of three parts of unequal lengths and differing basement morphologies: an eastern sector composed of rugged, subparallel basement ridges; a low-lying central sector with subdued basement morphology; and a western sector consisting of seamounts and guyots (including Tristan da Cunha and Gough islands). Rock samples and geophysical data suggest that the Ridge is composed of alkali basalt which becomes progressively older eastwards. Gravity data indicate that at least parts of the ridge are in local isostatic equilibrium. A mantle plume mechanism of formation is rejected in favour of a centre of abnormally high volcanic activity on the spreading ridge axis. The location of this centre, whose relative movement has been southwards, is determined by fracture zones crossing the spreading ridge axis.

Description: Observations of the temporal and spatial distribution of N2O in solution are not yet sufficient to permit quantitative assessment of the role of the ocean in the budget of atmospheric N2O. Consideration of the global nitrogen cycle suggests that the land should be the primary source of N2O. The gas is removed in the atmosphere by photolysis and by reaction with O(1D), and there may be additional sinks in the ocean.

Description: The Cape Verde Islands are emerged portions of a Mesozoic-Cenozoic volcanic accretion in the form of a westward-opening horseshoe along fracture zones converging from the mid-Atlantic ridge toward Africa. An interior abyssal plain slopes westward, increasing in depth from 2.7 to 4.5 km. The plain is underlain by low relief on acoustic basement that is associated with a 300-gamma negative magnetic anomaly. The flanks of the Sal-Maio ridge appear bounded by large-displacement normal faults; superficial slumping is common. The trends of magnetic anomalies are linear N-S north of the islands and less linear within the islands and may change coincident with E-W bathymetric trends south of the islands. A triangular pattern of reversed refraction lines 200–250 km long along the north and east ridges and NW-SE across the interior abyssal plain indicated 2–3 km of semiconsolidated sediments underlain by 3–6 km of basalt and 6–8 km of plutonic rocks. The depth of the Moho is between 16 and 17 km. A deep NW-SE trending fault intersects the Sal-Maio ridge near Boa Vista. The consistent depth to Moho and the regional Bouguer anomaly indicate lack of local relief at the base of the crust. The crustal load of the entire archipelago is regionally adjusted.

Description: Temperature data are presented which were obtained by means of a towed thermistor cable during the expedition "Auftrieb '72" in the immediate vicinity of the continental slope within the NW African upwelling region. While most of the data have been sampled on the offshore side of the upwelling front, the front is crossed on a few occasions, and some data cover the area of the upwelling coastal jet. They reveal a very deep homogeneous surface ]ayer within the coastal jet, indicative for increased turbulent mixing. These conclusions from the temperature sections are confirmed by the temperature and salinity data from CTD casts made in the same area at the same time. In spite of the complicated hydrography of the area and the large number of water masses involved, the existence of a zone of increased turbulent mixing within the jet is indicated in the data.

Description: Biological, hydrographical and chemical parameters were analysed from surface survey maps, drogue experiments and tracks in the region between Cap Blanc and Cap Timiris off NW Africa between January and March 1972 during the "Meteor"­ Expedition "Auftrieb '72". The chemical data measured included the nutrients: nitrate, nitrite, ammonia, silicate and phosphate as well as oxygen, particulate organic carbon and particulate organic nitrogen. In the area under investigation three different watermasses could be defined by nutrient content and salinity: namely "South Atlantic Central Water" (SACW), "Old Surface Water" and water from the Banc d' Arguin ("Bankwater"). The nutrient content and salinity of the fresh upwelled water at the surface showed that it consisted mainly of SACW that had always been mixed with one of the other watermasses. Mixing between Bankwater and SACW probably takes place close to the seabed on the shelf edge where cells of Bankwater were found several times. The surface survey maps show active upwelling only on the onshore ends of shelfedge canyons. This spatial heterogenity together with the discontinuities in the upwelling processes might explain the fact that no processes with time could be followed during buoyed parachute drogue experiments. The atomic ratio of nutrient uptake was found to be about N: Si: P = 15: 12 : 1 for the first few days of phytoplankton uptake in fresh upwelled water. From a comparison of the original concentration of the nutrients in fresh upwelled water and the calculated uptake, it follows that silicate might pose as a limiting factor after some days. Two sets of data from drogue experiments indicate that biological oxygen production as estimated from nitrate uptake, is sufficient to explain the oxygen input to fresh upwelled water. Thus physical solution of oxygen from the air appears to be slight.

Description: During the "Atlantic Trade Wind Experiment (ATEX)" from Feb. 6th to 23rd, 1969, an intensive aerological programme and detailed measurements near the sea surface were carried out simultaneously from three ships in the Atlantic northeast trade. From these data the kinematics, the dynamics and the kinetic energy budget of the trade wind flow in the lowest 3 km are investigated in this paper. The vertical shear of the horizontal wind vector is small in the mixed layer (lowest 600 m); a weak maximum is indicated at 400 m. Below about 1OOO m the large-scale horizontal flow is always divergent. Consequently, a large-scale sinldng motion of 300 to 500 m per day is observed through that level; sinking motion is also present at the trade wind inversion (1400 m). A considerable weakening of the divergence is noted during a period when the intertropical convergence zone (ITCZ) overrides the southern portion of the ATEX triangle. The northward displacement of the ITCZ is accompanied with a low pressure system approaching from the middle latitudes. The thermal wind vector is constant below the inversion and directed almost opposite to the surface geostrophic wind vector. Consequently, the magnitude of the geostrophic wind decreases rapidly with height while its direction remains nearly constant. The difference between the actual and the geostrophic wind vanishes at about 1200 m. Convective motions contribute to the small-scale vertical momentum transport. At the wind maximum the convective momentum transport amounts to about 30% of the surface stress. In a layer extending 300 m above the wind maximum the momentum is transported downward against the vertical gradient of the mean motion. The kinetic energy of the mean motion generated by the large-scale pressure gradient within the lowest 1OOO m primarily serves to balance the loss of mean kinetic energy due to conversion into turbulent kinetic energy in the surface boundary layer (lowest 20 m). In order to provide a reasonable description of the turbulent kinetic energy budget below the inversion the effects of condensation and evaporation within the cloud layer have to be taken into account.

Description: In the tropics mean diurnal courses of air pressure and wind system show many similarities. To test the well known theoretical considerations data of three Atlantic "Meteor" expeditions are used: The "Meteor Expedition 1925 /27", the "Atlantic Expedition 1965 (IQSY)" and the "Atlantic Trade Wind Experiment (ATEX) 1969". The results show the response of the atmosphere to the semi-diurnal pressure oscillation. The diurnal oscillation of the wind system cannot be described by simple models. The influence of the continents upon the diurnal pressure wave seems to be dominant. The measurements close to the Intertropical Convergence Zone point to a diurnal variation of the inflow into the ITCZ.

Description: During the driftage of R. V. "Meteor" within the "Atlantic Trade Wind Experiment (ATEX) 1969" time series of wind velocity, air and sea temperature and humidity were measured on a buoy drifting windward of the disturbed zone of the ship. Using the profile method, vertical fluxes of momentum and sensible and latent heat were calculated. Time variations in the periodic range from 2.5 minutes to 5 days are analysed. Within the 18 days period the vertical fluxes of latent heat and momentum vary by a factor of 5 because of long period wind variations. For wind velocity, flux of momentum and flux of latent heat the variations in the range of periods greater than one day contribute most of spectral energy (65-85%) to total variance, while for air and water temperature, humidity and sensible heat flux the variations with periods smaller than one day represent more than 50% of total variance. For most of the mentioned variables the contribution of diurnal and semi-diurnal oscillations to total variance is small (3%), only for pressure, air and water temperature it is about 30% . The measurements during rain showers point out that even weak or moderate showers influence the surface layer right down to the sea surface. The amplitudes of the diurnal courses depends on the distance of the measurements to the air-sea interface. The diurnal course of water temperature follows the variation of incoming solar radiation, with increasing depth its amplitude is reduced and the phase is lagged. Applying the equation of diffusion to the diurnal harmonic water temperature oscillation down to 50 m depth, a coefficient of thermal diffusivity in water of K = 0.0525 - 0.00075 z (m2/s), decreasing with depth, was calculated. The diurnal variation of air temperature is influenced by the diurnal course of sea surface temperature. A semi-diurnal oscillation is superimposed by the semi-diurnal pressure wave because of adiabatic warming. The observed increase of the amplitude with height is caused by absorption of solar radiation. The stability of density stratification also shows a marked diurnal variation with a maximum of lability at night. This effects directly the variation of sensible heat flux. Humidity mainly shows a diurnal variation, the reason may be a diurnal variation of the divergence of vertical water vapor transport.

Description: By critical examination of the stratigraphical methods and interpretations applied to Eastern Mediterranean Quaternary sediments, "endemic" (Mediterranean) and "foreign" (non-Mediterranean) data are separated. Basing on the "endemic" data, cores of various authors are correlated by lithology as well as by Foraminifera frequency curves. Using "cycles" (containing a basal warm and the following cold period) a chronological interpretation of Foraminifera frequency curves, similar to that of PARKER (1958) is given. lt is applicable to curves of all authors.

Description: In the sediments of the NW African continental margin the mainly biogenic carbonate constituents become increasingly diluted with terrigenous material as one approaches the coast, as indicated by the carbonate-C02 content, the Al20a/Si02-ratios, and the presence of ammonia fixed to alumino-silicates, predominantly to illites. In the northern area of investigation - off Cape Blanc and Cape Bojador - the terrigenous constituents are mainly quartz from the Sahara Desert, whereas in the south - off Senegal - more alumino-silicates as clay minerals are admixed with the carbonate constituents. The organic carbon content of the continental slope sediments off Senegal is higher than in samples of the continental rise or of the shelf, indicating optimal conditions for the preservation of organic matter as a result of high production and relatively rapid sedimentation. The zone of manganese-oxide enrichment follows the redox potential of + 330 m V from the surface (0-5 cm) into the sediments (20-30 cm deep) at 2000-3000 m and 3700 m of water depths, respectively. At shallower water depths, low redox potentials preclude deposition of manganese oxides and cause their mobilization from the sediments. About 1/3 of the total sedimentary Zn and 1/4 of the Cu is associated with the carbonate mineral fraction, probably in calcium phosphate overgrowths as a result of the mineralization of phosphorus-containing organic matter. Besides the precipitation of calcium phosphate, the mineralization of organic matter mediated by bacterial sulfate reduction also results in calcium carbonate precipitation and the exchange of ammonia for potassium on illites. Because of these simultaneous reactions, the depth distribution of all mineralization constituents in the interstitial water can be determined using the actual molar carbon-to-nitrogen-to-phosphorus ratios of the sedimentary organic matter. The amount of sulfide sulfur in this process indicates the predominance of bacterial sulfate reduction in the sediments off NW Africa. This process also preferentially decomposes nitrogen- and phosphorus-containing organic compounds so organic matter deficient in these elements is characteristic for the rapidly accumulating sediments. During the last glacial stage there were more biogenic carbonates and organic matter accumulating in the sedimcnts than today, indicating there was increased production of organic carbon compounds and more favorable conditions for their preservation. During the last interglacial times conditions were similar to those of today. This differentiation with time has also been observed in sediments from thc Argentine Basin and from the slope off South India indicating perhaps world-wide environmental changes throughout Late Quaternary times.

Description: The cruises "Valdivia" 10 and "Meteor" 39/1975 had geological and geophysical investigations as focal points. They covered the northwest African continental margin between Morocco (33.5° N) and the southernmost Senegal (12° N) with the purpose: 1) to fill gaps from previous "Meteor" cruises, 2) to contribute to post-site surveys for DSDP Leg 41 (sites 367-370) and 3) to provide pre-site surveys for DSDP Legs 47 and 51 and IPOD crustal site 7 area around 21° N/32° W. The equipment used was similar to "Meteor" cruise 25/1971 with the main exceptions being the new multi-channel, digital seismic system of the BGR (Bundesanstalt für Geowissenschaften und Rohstoffe, Hannover) (Meteor 39-1), refraction seismic buoys, the Kiel multisonde for measuring physical oceanographic parameters (Meteor 39-2) and continuous television observations from a slowly moving ship (Valdivia 10-3). The activities are summarized in Table 1. The scien1ific goals, cruise log, equipment used, participants, profiles and station lists as well as some preliminary results form the contents of the report.

Description: Sedimentological and biostratigraphic investigations of 15 cores (total length: 88 m) from the vicinity of Great Meteor Seamount (about 30° N, 28° W) showed that the calcareous oozes are asymmetricaly distributed around the seamount and vertically differentiated into two intervals. East and west of the seamount, the upper "A"-interval is characterized by yellowish-brown sediment colors and bioturbation; ash layers and diatoms are restricted to the eastern cores. On both seamount flanks, the sediments of the lower "B"-interval are white and very rich in CaC03 with a major fine silt (2-16 μ) mode (mainly coccoliths). Lamination, manganese micronodules, Tertiary foraminifera and discoasters, and small limestone and basalt fragments are typical of the "B"-interval of the eastern cores only. The sediments contain abundant displaced miaterial which was reworked from the upper parts of the seamount. The sedimentation around the seamount is strongly influenced by the kind of displaced material and the intensity of its differentiated dispersal: the sedimentation rates are generally higher on the east than on the west flank (e.g. in "B" : 0.9 cm/1000 y in the W; 3.1 cm/1000 y in the E), and lower for the "A" than for the "B"-interval. The lamination is explained by the combination of increased sedimentation rates with a strong input of material poor in organic carbon producing a hostile environment for benthic life. The CaC03 content of the cores is highly influenced by the proportion of displaced biogenous carbonate material (mainly coccoliths). The genuine in-situ conditions of the dissolution fades are only reflected by the minimum CaCOs values of the cores (Fig. 23; CCD = about 5,500 m; first bend in dissolution curve = 4,000 m; ACD = about 3,400 m). The preservation of the total foraminiferal association depends on the proportion of in-situ versus displaced specimens. In greater water depths (stronger dissolution), for example, the preservation can be improved by the admixture of relatively well preserved displaced foraminifera. Carbonate cementation and the formation of manganese micronodules are restricted to microenvironments with locally increased organic carbon contents (e.g. pellets; foraminifera). The ash layers consist of redeposited, silicic volcanic glass of trachytic composition and Mio-Pliocene age; possibly, they can be derived from the upper part of the seamount. Siliceous organisms, especially diatoms, are frequent close to the ash layers and probably also redeposited. Their preservation was favoured by the increase of the Si02 content in the pore water caused by the silicic volcanic glass. The cores were biostratigraphically subdivided with the aid of planktonic foraminifera and partly also coccoliths. In most cases, the biostratigraphically determined cold- and warm sections could be correlated from core to core (Fig. 21). Almost all cores do not penetrate the Late Pleistocene. All Tertiary fossils are reworked. In general, the warm/cold boundary W2/C2 corresponds with the lithostratigraphic A/B boundary. Benthonic foraminifera indicate the original site of deposition of the displaced material (summit plateau or flanks of the seamount). The asymmetric distribtttion of the sediments around the seamount east and west of the NE-directed antarctic bottom current (AABW) is explained by the distortion of the streamlines by the Coriolis force; by this process the current velocity is increased west of the seamount and decreased east of it (Fig. 25). The different proportion of displaced material within the "A" and "B" interval is explained by changes of the intensity of the oceanic circulation. At the time of "B" the flow of the AABW around the seamount was stronger than during "A"; this can be inferred from the presence of characteristic benthonic foraminifera. The increased oceanic circulation implies an enhanced differentiation of the current velocities, and by that, also of the sedimentation rates, and intensifies the winnowing processes on the seamount plateau. The winnowed sediment material was transported downslope by turbid layers into the deep-sea, incorporated into the current system of the AABW, and asymmetrically deposited around the seamount.

Description: 1. 52 species of Crustacea Decapoda Reptantia, one of which new, were obtained on the cruises of R. V. "Meteor" dealt with in this paper. 2. The status of Euchirograpsus liguricus and E. americanus is discussed in some detail. It is shown that E. americanus is restricted to the western Atlantic, while E. liguricus occurs only in the eastern Atlantic. Records of E. americanus outside the western Atlantic are due to confusions with E. liguricus or other new species which have been described elsewhere (TÜRKAY 1975). 3. 3 species ( Polycheles crucifera, Munida iris ruttlandi, Cymonomus normani) are recorded for the first time from the Portuguese and 4 species ( Polycheles granulatus, Munida iris ruttlandi, Jaxea nocturna1, Macropipus rugosus) from the Moroccan coast. 4. The characterization of the Moroccan and Lusitanic province may be performed quantitatively rather than qualitatively. Further investigations are needed in order to get complete results.

Description: This paper deals with Euphausiacea collected in the upwelling region off Northwest Africa between Cap Blanc and Cap Mirik (Timiris) during the voyages 19 (1970) and 26 (1972) of the research vessel "Meteor". 20 species have been recorded, 4 of these dominate in the area under study. Euphttsia krohnii, Nematoscelis megalops and Thysanoessa gregaria are atlantic temperate species, whereas Nyctiphanes capensis inhabits neritic areas around the edge of the Banc d' Arguin, together with Euphausia hanseni from the Southern Atlantic. The population density of the euphausiids in the upwelling area is very high. The vertical distribution of the dominant species E. krohnii and N. megalops reveal significant differences. E. krohnii occurs down to a depth of 200 m, whereas N. megalops lives between 100 and 300 m. The shelf and the edge of the shelf (down to 2000 m) are populated by different species. On the shelf, adult and juvenile N. capensis predominate, but great numbers of juvenile N. megalops have also been found. Along the edge of the shelf E. krohnii, N. megalops and T. gregaria are most abundant. E. hanseni was represented by juveniles, both on the shelf and along its edge. Comparing the species composition of the area under study with that of other regions of the North Atlantic, the dominant species exhibit certain similarities with the species present near Cap Verde and Canary Island, but none similarities could be established with the Great Meteor Seamount. The reasons for this situation are discussed.