ALBERT

Description: The Atlantic Advisory Panel proposed that Site 8 should be drilled on the rise between the Hatteras and Sohm Abyssal Plains (lat 35° 2l'N., long 67° 3l'W.) This location was considered to offer the best opportunity for realizing two primary objectives. The first of these objectives was to sample and date the oldest available rock in a region adjacent to the North American continent and as far as possible from the Mid-Atlantic Ridge. The second objective relates to the potential paleobiological and paleoecological information that could be derived from the sedimentary column in this general area.

Description: Site 12 of this report formerly was designated 14 by the Atlantic Advisory Panel. It was drilled in the Cape Verde Basin (latitude 19° 42'N, longitude 26° 01'W), which is underlain by 2000 to 2100 feet (0.9 to 1.1 seconds reflection time) of sediment. The bottom topography of the basin is fairly smooth but not to the degree of an abyssal plain. Site 12 was selected to provide material for paleontological investigations.

Description: The preliminary planning and approach to site 13 were taken from the JOIDES Atlantic Advisory Panel Report and from a previous detailed survey of the site by R/V Vema of the Lamont Geological Observatory. Several CSP profiles crossing the selected site in various directions show an uplifted portion of the sea floor roughly circular in shape of about 10 kilometers in diameter. In contrast to the smooth bottom of the surrounding abyssal plain, the topography of the small rise selected for the site has a small-scale roughness of amplitude of 40 to 80 meters. The work reported here is a biostratigraphic summary of available samples. Only the most important and biostratigraphically significant components of the faunas have been noted. No attempt has been made to give an exhaustive faunal analysis of the samples seen.

Description: The Atlantic Advisory Panel proposed that Site 9 should be drilled on the northeastern flank of the Bermuda Rise (lat. 32° 37' N., long. 59° 10' W.), which is about 100 miles west of the Sohm Abyssal Plain. The bottom of this region consists of low linear ridges that are roughly parallel and oriented in a northwest-southeasterly direction. Scattered seamounts, some of which have peaks 2000 fathoms (3660 meters) below sea level, arise from the otherwise featureless sea floor between the ridges. The primary purpose in drilling Site 9 was to examine a sedimentary column where seismic reflectors were largely absent and to determine the age of sediments overlying acoustical basement in the examination of sea floor spreading.

Description: Prior to arrival on this site, the only survey data available was from the Vema-20 crossing of the area. The recommended site location was over a relatively smooth valley in the bottom topography at about 4750 meters (15,580 feet) depth (uncorrected), about 10 kilometers wide E-W between peaks (or ridges) on either side. Sediment thickness was unknown. The center of the valley is near the peak of a wide (40 to 50 kilometers) positive magnetic anomaly, identified as Magnetic Anomaly 30 in the hypothesized geomagnetic time scale with an age of 72 million years.

Description: The drilling objectives at this site were to complete the cored section begun at Site 23 in accordance with the recommendations of the JOIDES Atlantic Advisory Panel, presented in the Site 23 report. The location coincides with a position on the southeastern side of the elevated portion of basement in this area.

Description: At the Leg 4 pre-cruise meeting in Miami, Florida, in January 1969, the Ridge site was proposed as an additional site to be investigated, if possible. Since the water depth and sediment thickness at this site were both minimal (2000 meters and less than 100 meters, respectively) and the location was not far from the track between initially planned sites, the shipboard party decided, upon completion of work at Site 24, to make a 24-hour drilling effort on the North Brazilian Ridge. The drilling objectives at this location were to sample and date the sediments atop the Ridge crest and to determine the nature, age and origin of the consolidated material beneath the thin mantle of sediment.

Description: The northern margin of the Demerara Abyssal Plain is bordered by a low ESE-WNW trending rise known as the Barracuda Ridge. North of South America, the eastern margin of the Demerara Abyssal Plain is formed by the Barbados Ridge. An extensive sedimentary section of the Barbados Ridge is exposed on the island of Barbados and consists of a series of radiolarian to planktonic foraminiferal and calcareous nannofossil biogenic sediments interlayered with ash beds. To determine the nature of the sediments and "basement," Site 27 was selected on the northern margin of the Demerara Abyssal Plain, south of the Barracuda Ridge.

Description: The southern Caribbean basins are thought to be part of a relatively old and geologically stable crustal plate. Although surrounded by belts of high earthquake activity, the central Caribbean is seismically quiet. The region also constitutes a quiet magnetic zone and appears to have resisted all of the surrounding forces related to ocean floor spreading. In addition to providing considerable information on the general geologic history of the Caribbean region, paleontologic studies on cores at Site 29 were expected to provide valuable data on phylogenetic trends within the planktonic foraminifera and calcareous nannoplankton, furnishing more accurate criteria for intercontinental stratigraphic correlation. The work reported here is a biostratigraphic summary of available samples. only the most important and biostratigraphically significant components of the faunas have been noted. No attempt has been made to give an exhaustive faunal analysis of the samples seen.

Description: Site 26 was selected on the crest of the Mid-Atlantic Ridge between 15°N and 5°S is offset to the east nearly 4000 kilometers through a series of fracture zones. One of the most prominent of these is the Vema Fracture Zone, a narrow east-west trending trough which cuts through the Mid-Atlantic Ridge at latitude 11°N.

Description: The cores and dredges described in this report were taken on the ARIES Expedition from November 1970 until October 1971 by the Scripps Institution of Oceanography from the R/V Thomas Washington. A total of 65 cores and dredges were recovered and are available at Scripps for sampling and study.

Description: The BLM-OCS (Bureau of Land Management-Outer Continental Shelf) program was designed to establish chemical, biological, and geological baseline on the South Texas Continental Shelf. The focus for the geological program was to establish the nature and amount of the suspended sediment in the water column, of the Holocene sediments on the shelf, and to identify and locate regions of geology conditions which may be hazardous to OCS operations. To accomplish these goals three cruises were planned. The report constitutes results of the first cruise. The results of these cruises associated with the subsequent laboratory analysis, enabled to establish a detailed baseline in order to provide significant geologic and biologic data for environmental assessment. Dredges recovered are available at University of Texas (see: BLM/OCS South Texas Outer Continental Shelf (STOCS) Project Sediment Data http://www.ngdc.noaa.gov/docucomp/page?xml=NOAA/NESDIS/NGDC/MGG/Geology/iso/xml/G02888.xml&view=getDataView&header=none).

Description: The BLM-OCS (Bureau of Land Management-Outer Continental Shelf) program was designed to establish chemical, biological, and geological baseline on the South Texas Continental Shelf. The focus for the geological program was to establish the nature and amount of the suspended sediment in the water column, of the Holocene sediments on the shelf, and to identify and locate regions of geology conditions which may be hazardous to OCS operations. To accomplish these goals three cruises were planned. The report constitutes results of the second cruise. The results of these cruises associated with the subsequent laboratory analysis, enabled to establish a detailed baseline in order to provide significant geologic and biologic data for environmental assessment. Dredges recovered are available at University of Texas (see: BLM/OCS South Texas Outer Continental Shelf (STOCS) Project Sediment Data http://www.ngdc.noaa.gov/docucomp/page?xml=NOAA/NESDIS/NGDC/MGG/Geology/iso/xml/G02888.xml&view=getDataView&header=none).

Description: The rate of accumulation of a ferromanganese coating on a fragment of pillow basalt was estimated using a variety of techniques. Unsupported 230 Th activity decrease in the oxide layer, K/A dating of the basalt, fission tracks dating of the glassy layer around the basalt, thickness of the palagonitization rind, and integrated 230 Th activity give ages from approximately 3 x 10-6 years to 5 x 10-3 years. Data suggest that the ferromanganese material formed rapidly (33 mm/10-6 years) and by hydrothermal or volcanic processes.

Description: During U.S. Department of Interior, Bureau of Land Management (BLM) public hearings held in 1973, 1974 and 1975 prior to Texas Outer Continental Shelf (OCS) oil and gas lease sales, concern was expressed by the National Marine Fisheries Service, scientists from Texas A&M and the University of Texas and private citizens over the possible environmental impact of oil and gas drilling and production operations on coral reefs and fishing banks in or adjacent to lease blocks to be sold. As a result, certain restrictive regulations concerning drilling operations in the vicinity of the well documented coral reefs and biostromal communities at the East and West Flower Gardens were established by BLM, and Signal Oil Company was required to provide a biological and geological baseline study of the less well known Stetson Bank before a drilling permit could be issued. Considering the almost total lack of knowledge of the geology and biotic communities associated with the South Texas OCS banks lying in or near lease blocks to be offered for sale in 1975, BLM contracted with Texas A&M University to provide the biological and geological baseline information required to facilitate judgments as to the extent and nature of restrictive regulations on drilling near these banks which might be required to insure their protection. In pursuit of this, scientists from Texas A&M University were to direct their attention toward assessments of ground fish populations, unique biological and geological features, substratum type and distribution, and the biotic and geologic relationships between these banks and those farther north.

Description: The volcanic deposits which surround Vulcano Island may be classified in four phases : a detritic phase, fed from the Island itself and from Sicily; a siliceous and carbonateous organic phase; a neogenesis mineral phase; a precipitation phase. The formation of clay and the mineralization of iron and manganese are the subject of particular study. A number of indications suggest the littoral neogenesis of kaolinite around hydrothermal issues, and the formation of smectite at greater depths. The distribution of iron mineralization in the Baie du Levant follows the physicochemical variations of the environment. Melnikovite, pyrite, marcassite and pyrrhotin are dispersed in aureoles around swallow emission points (fumaroles). Close to the hydrothermal spring, iron precipitates are found in the form of amorphous hydroxydes, while geothite and hematite characterize the deeper area as a whole. Manganese mineralizations are exclusively represented by hydroxides and oxides, locally (about - 250 m) organized as incrustations on. lapilli glasses (micronodules). These would appear to be related to the hydrothermal spring.

Description: At Sites 47 and 48, impenetrable and cherty Upper Cretaceous chalks were found. The upper part of what infer to be lower Cretaceous is even more reflective, and likely to be very cherty (and was found to be cherty in the Vema core). It became clear that basement could only be reached where the Upper Cretaceous and the upper part of the lower Cretaceous are absent. However, west of Site 48, the R/V Argo record showed an area in which the Upper Cretaceous has wedged out down dip, and the Lower Cretaceous is thinning out by loss of the strongly reflective beds at the top. This area appeared to offer the best chance for sampling the lowermost transparent layer. Two holes were drilled: Hole 49.0 and Hole 49.1 after Hole 49.0 stopped at 18 m. Beds near the base of sedimentary sequence revealed by the seismic profiles are found to be of early Cretaceous (Neocomian) or latest Jurassic (Tithonian) age, and of pelagic facies. The crust under the Shatsky Rise is latest Jurassic or older.

Description: Site 49 had been selected to investigate the basal part of the sedimentary sequence as revealed by the acoustic profiles, and to sample the underlying opaque material. However, the cherty nature of the sediments prevented penetration of the section at Site 49, and the only recourse appeared to be to move to a spot of even thinner sedimentary cover. Such a place existed, just downslope from Site 49, where Horizon B' comes very close to the surface, this is where Site 50 was selected.

Description: Having been stopped by chert in the Maestrichtian at Site 47, a site was looked for which would give an adequate Cenozoic thickness for satisfactory spudding-in, yet promised to lead from this into an older part of the section. This is the first record of Middle Maestrichtian in pelagic carbonate facies from the Northwest Pacific and surrounding lands, a matter of paleontologic-biostratigraphic importance.

Description: During the fourth and fifth legs of Scan Expedition, drill Sites 53 and 60 were surveyed and Site 59 was traversed. In addition to the drill site surveys, several other areas across the Mariana Arc System were investigated in some detail, guided by reconnaissance work aboard the R/V Argo from the previous year. The remarkable similarities in the occurrence and relative positions of a wide range of structural features in western Pacific arc systems strongly suggest a common mechanism of origin. The area in which crustal deformation related to island arc tectonism is occurring, more extensive and complex than generally recognized, is defined as the active island arc system; this includes not only the trench and volcanic chain, but also the deep basin and submarine ridge on the concave side of the active volcanoes.

Description: The results at Site 59 suggested that Mesozoic sediments are present beneath a thin Tertiary cover in the region north of the Caroline Ridge near the Mariana Trench. Since one of the principal objectives of the drilling program was to find old Pacific crust, and since the section at Site 59 was not fully penetrated, it seemed worth a determined effort to go beyond the level reached at Site 59, somewhere in the same general area, in an attempt to reach basement. As the reflection profile taken by Argo (SCAN Leg V) through Site 59 shows the section above thesmooth basement reflector (Horizon B?) thinning northwestward from about 0.3 to 0.15 second, by loss of part of the lower "transparent" layer, this is were Site 61 was located.

Description: The sedimentary section at Site 62 on Eauripik Ridge can be traced eastward into the East Caroline Basin. It was decided to drill a hole to basement in the eastern part of East Caroline Basin to determine the age of the upper strong reflectors and to test the hypothesis that sediments older than any at Site 62 are present. A nearly complete section was obtained from middle Oligocene to Quaternary, unconformably overlying basalt containing middle Oligocene chalk xenoliths. The sediments consist of chalk and chalk ooze in the Oligocene and Miocene, and of marl ooze and calcareous clay in the Pliocene and Quaternary.

Description: The interstitial water received at UCLA from Leg 7 (Guam to Hawaii) consisted of forty-two samples of approximately 5 milliliters each, three samples of approximately 10 milliliters each, and three samples of approximately 100 milliliters each. These pore waters had been squeezed from sediments consisting primarily of biogenic ooze, and had been collected at five different drilling sites along the route. High cobalt value were observed at Site 66 and were accompanied by a relatively high manganese concentration, but more normal iron, nickel and copper concentrations. This apparent cobalt enrichment could not be explained at the time of procedure. The line Islands area were Site 66 is situated was later notoriously known for its high Co values in manganese crust deposits (see, He, G., Ma, W., Song, C., Yang, S., Zhu, B., Yao, H., Jiang, X., Cheng, Y., 2011. Distribution characteristics of seamount cobalt-rich ferromanganese crusts and the determination of the size of areas for exploration and exploitation. Acta Oceanologica Sinica 30, 63–75. doi:10.1007/s13131-011-0120-9).

Description: Site 67 is on the Hawaiian Arch, in the general region selected for one of the Mohole Project sites. Therefore, intensive geophysical surveys have been made in the area. The objectives were to penetrate the entire sedimentary sequence to basement in order to learn the petrology and ages of the sediments and of the seismic reflectors, and to obtain samples of the underlying basement rocks. Well consolidated and bedded volcanic sandstone and mudstone, and claystone were found to extend from the sea floor to a depth of 60 meters, where a layer of hard brown porcelanite stopped the bit. Displaced radiolarians in mud from a core at 60 meters indicate sediments of early Eocene or late Paleocene age are present somewhere above that depth.

Description: An acoustically very transparent layer is present over much of the deep basin—here termed the Central Basin—between the Gilbert and Marshall Islands on the west and the Line Islands on the east. The Pacific Panel recommended drilling in this region to sample at least the upper transparent layer, and the first opaque layer beneath. Several possible sites were considered by the panel and by the shipboard party. Of paramount importance in choosing a particular site was a concern that sufficient sediments be present to bury the bottom-hole assembly (the drill collars and bumper subs) before the bit struck hard rock. A set of nearly continuous cores of an apparently uninterrupted section of radiolarian ooze ranging in age from middle Eocene to Recent was obtained, but the bit did not reach the deepest seismic reflector. Below depths of 127 meters, in the Oligocene and Eocene, thin chert and turbidite beds are sparsely interbedded with ooze.

Description: One of the principal objectives in the Central Pacific Basin was to elucidate the Paleobathymetric history of the region, which is located amidst groups of atolls and guyots that have subsided as much as 2 kilometers since mid-Cretaceous times. After failure to penetrate the entire sedimentary section and to sample basement at Site 65, on the west side of the Central Basin another site in the Basin where basement rocks might be sampled was searched. Likely places were known from unpublished reflection profiles on the east side of the Basin near the Line Islands by the Hawaii Institute of Geophysics. Finally it was decided to drill a transparent section once again in this area acoiding turbidites formations.

Description: Site 70 is located about 20 miles north of the northern boundary of the Clipperton Fracture Zone near 140° W. It is the northernmost of the N-S line of sites drilled during Leg 8 to investigate the east-west trending accumulation of sediment centered at about 2°N near 140°W. It lies about 500 miles south of Site 42 of Leg 5, the southernmost of a line of sites continuing to the north. The R/V Argo SCAN survey indicated that the area was one of low, broad abyssal hills, 2 to 10 miles in width on E-W profiles, with relatively thick sediment cover.

Description: Site 74 is located 250 miles northeast of the Marquesas Islands and lies 270 miles south of Site 73 and 400 miles north of Site 75. It is one of the sites along the N-S line drilled during Leg 8 to investigate the east-west trending accumulation of sediments centered about 2°N near 140°W. Site 74 is located near the center of a relatively flat area about 3 miles across. There is some indication of minor deformation at the site.

Description: Site 75 is located 300 miles southeast of the Marquesas Islands; 400 miles south of Site 74. It is the southernmost of the sites along the N-S line drilled during Leg 8 to investigate the east-west trending accumulation of sediments centered about 2°N near 140°W. This site is a replacement for the site at 31°S originally chosen by the JOIDES Pacific Advisory Panel (PAP Site 27). The original site was not drilled since a preliminary R/V Argo SCAN survey indicated insufficient sediment thickness.

Description: Site 76 was selected in order to core a thick sequence of sediments north of the Tuamotu ridge that had been crossed by Glomar Challenger justprior to the termination of Leg 8 in Tahiti. Two holes at this site continuously cored 27 meters of lower Pliocene to Recent phillipsitic clay and calcareous nannofossil ooze interbedded with calcareous turbidites. The drill bit was stopped by a silicified calcareous turbidite of Early Pliocene age.

Description: Site 79 is located on the crest of the equatorial Pacific sediment belt (Ewing and others, 1968) and is the westernmost of a series of sites (79, 81, 82 and 83) that follow the crest of this belt eastward to and across the crest of the oceanic ridge, locally known as the East Pacific Rise. The purpose of these sites is two-fold: 1) to study variations in biostratigraphy and sediment type from west to east across the Pacific and 2) to paleontologically date basement and determine the rate of spreading of the Pacific plate since the time of deposition of the oldest sediments at Site 77.

Description: The origin of the Campeche Escarpment in the Gulf of Mexico has been attributed to several causes. Some suggest that the scarp represents a fault scarp, others suggest that its origin is a function of upbuilding and outbuilding likened, in some cases, to that of delta building. Still others suggest that the scarp represents the detrital accumulation seaward of a barrier or reef complex. In order to clarify these possible interpretations, Site 86 was located on a bench at a depth of 780 fathoms in the vicinity of the Campeche Escarpment.

Description: The principal objective at this site was the recovery of Mesozoic sediment and a sample of Horizon B (or basement). The location chosen for drilling is about 40 nautical miles southeast of San Salvador in 4914 meters of water. Aside from the possibility of recovering the oldest Atlantic sediment, drilling at this site was expected to produce interesting samples for comparison stratigraphically and lithologically with those of Holes 4 and 5 of Leg 1.

Description: In view of the fact that thick sections of Neocomian and Jurassic limestone were found in the region off the Bahama Islands (Holes 99A, 100 and 101) a hole was selected for drilling between New York and Bermuda at a position where knowledge might be gained about the structure and composition of the lower continental rise hills. In addition, such a hole would ascertain the age of the crust.

Description: Orphan Knoll is a pronounced submarine feature at the foot of the continental rise and bounded on its northeast side by the 4000-meter deep abyssal plain of the Labrador Basin. It lies isolated on the ocean floor some 550 kilometers northeast of Newfoundland and 350 kilometers north of Flemish Cape. The DSDP drilling site 111 was originally chosen by the Atlantic Advisory Panel on the basis of Charcot's Flexotir continuous seismic profile provided by CNEXO.

Description: The growth rate of a manganese nodule from the South Atlantic Ocean (Rio Grande Ridge) has been determined using a 10Be profile as measured with a Tandem Van de Graaff accelerator. This rate is 4.5 mm /My. A correlation may exist between the 10Be flux and the Mn flux to nodules.

Description: Seismic reflection profiles across the Labrador Sea by Vema-19 and Charcot-S had revealed a rugged basement topography almost entirely buried by sediments up to 2000 meters thick. It was first suggested that this was the median valley of a mid-Labrador Sea ridge where oceanic crust was generated during the last phase of opening of the Labrador Sea but which is now virtually inactive and covered by sediment. The choice of a site where basement could be dated by sampling sediments that were believed to be the same age as the basement was difficult. Site 113 was eventually chosen in a local valley 8 kilometers south of a small knoll believed, from the Vema-ll record, to be a basement high.

Description: The principle objective at Site 118 was to sample a formation in the Bay of Biscay which had been tentatively ascribed to Lower Cretaceous or older sediments. However it was not clear that this corresponding seismic layer was not in fact part of an extremely irregular igneous basement structure, at least at the western end of the bay.

Description: The western margin of Sardinia (had been explored in the Spring of 1970 by the R/V Jean Charcot of CNEXO. It showed that the basement ridge west of Sardinia lies at the very distal edge of the continental slope and has effectively dammed an upslope sedimentary basin which is presently isolated from the Balearic Abyssal Plain. Consequently a series of holes was contemplated along an east to west transverse of the Charcot profile.

Description: The single "raison d'être" for selecting Site 126 was to explore the pre-evaporite history of the eastern Mediterranean and hopefully to establish the paleoenvironment which preceded the Late Miocene salinity crisis. The selcetd site is in a deep cleft in the Mediterranean Ridge in the central Ionian Sea, a cleft that cuts more than 250 meters below the level of Horizon M and at the same time is floored by flat-lying sediments. A secondary objective of the cleft site-selection was to ascertain what kind of sediment makes up the horizontal fill and hopefully to determine some details of the history and mechanics of the depression-filling process.

Description: Site 172 was continuously cored to a depth of 24 meters in a sediment pond 140 kilometers south of the Murray fracture zone. The upper 9 meters consist of a moderate brown pelagic clay which changes to a zeolite-rich brown clay, brown clay zeolitite and zeolitite in the lower 9 to 24 meters. An Early Oligocene (35 to 38 my) nannofossil horizon occurs near an extrusive basalt encountered at 24 meters. These sediments are older than the 29 my age indicated by a recent identification of magnetic anomaly 8 in the "disturbed" zone. The age discrepancy suggests that the magnetic anomalies in the "disturbed" zone are still not identified correctly.

Description: Basal sediments cored above alkali basalt at Site 183 beneath the Aleutian Abyssal Plain include iron-rich clays, a geothite-bearing calcareous ironstone (23.8% Fe and 4.16% Mn, CaCO3-free), and a pyrite-bearing unfossiliferous aragonitic limestone with 1.95 per cent Sr. At Hole 192A, atop Meiji Guyot, the northernmost of the Emperor Seamounts, five meters of iron and manganese-enriched clays interlayered and diluted with chalk lie on extrusive alkali basalt pillow lavas beneath almost a kilometer of silts, clays, and diatomaceous oozes.

Description: The main objectives of Leg 17 were to establish the regional pattern of oceanic crustal ages in the central Pacific, to obtain cores of the entire stratigraphic succession, especially from pre-Middle Eocene strata, To document the history of growth and subsidence of seamounts located along seamount chains, by drilling on the archipelagic apron of sediments near the foot of individual seamounts and to sample acoustic reflectors seen on seismic reflection profiles and to establish their physical properties and their ages.

Description: The oceanic region between the Tonga-Kermadec Trench and New Zealand to the east and Australia to the west (see map at the back of this volume) has long been regarded as an anomalous region. Prior to development of the plate tectonic theory, it was known that the eastern boundary of the region was tectonically active, the western relatively passive. The DSDP Leg 21 overall objective was to provide initial coring data which would aid in reconstructing the tectonic history and relative plate movements of the Pacific and Indian crustal plates and determining the age of the tectonic features contained within the Tasman Sea region. In particular, the age and biostratigraphy of the oldest Pacific crustal section now being subducted into the Tonga-Kermadec Trench (Site 204) and the age and composition of the South Fiji Basin and of the basement rock (Site 205).

Description: The sea floor of the western Pacific is covered by five stratigraphic units: (l)an eastward thinning wedge of late Tertiary silty clay, primarily of volcanic origin, (2) a Cretaceous to Tertiary zeolitic red clay, (3) a Late Cretaceous to Tertiary chalk/chert sequence, (4) a Cretaceous clay, and (5) a basal chalk/chert sequence. The basal chalk was deposited on the young crust at the crest of the mid-oceanic ridge, while the upper chalk was deposited beneath the equator, and the abyssal clays were deposited in abyssal depths in mid latitudes. A kinematic model has been constructed that outlines the deposition of these units on growing crust, which not only was displaced westward away from the accretion center of the mid-oceanic ridge, but northward under the equator. The average northward component of motion for the Pacific plate has been 2 cm per year from 0 to 30 m.y. and 4.4 cm per year from 30 to 100 m.y. The deep-sea deposits of the Pacific are basically and systematically time transgressive. Claims of general synchroneity for either lithostratigraphy or acoustostratigraphy are rejected as inconsistent with both the drilling data and the kinematic model of Pacific pelagic stratigraphy. A few more well sampled holes in the ancient Pacific plate combined with an appropriately refined kinematic model should yield a 'rather detailed history of the Pacific plate since the Jurassic.

Description: Eight sites were drilled on Leg 22 in the northeastern Indian Ocean. Three sites (214, 216, 217) on Ninetyeast Ridge penetrated a thick sequence of mostly Tertiary calcareous oozes passing down into shallow-water sediments with volcanogenic material in Sites 214 and 216. The age of the basal sequence increases northwards from Paleocene (214) through Maastrichtian (216) to Campanian (217). A nonmarine sequence of volcanoclastics and lignite overlies basalt at 214. Drilling terminated in a dolomite chert sequence at 217 before bsalt was encountered. Two sites (213, 215), in deep water on either side of Ninetyeast Ridge, showed calcareous ooze of Paleocene to early Eocene age overlying basalt passing up into brown clay and finally siliceous ooze of late Miocene and younger age. A major hiatus centered in the Oligocene occurs at both these sites. One site (212), drilled in the deepest part of the Wharton Basin, penetrated a brown clay sequence interbedded with several thick calcareous units, each of a very short time duration. Evidence from sedimentary structures and calcareous microfossils.

Description: Leg 14 of the Deep Sea Drilling Project completed 9 holes; 7 were located off NW Africa, 1 in Ceara Abyssal Plain, and 1 on Demerara Rise. Quaternary and Pliocene sediments consist of nanno chalk oozes and brown clay. The facies boundary (CCD) is near 5000 meters. Sedimentation rates are between 10 and 30 meters/million years (m/My) for chalk ooze and 2 to 4 m/My for pelagic clay. Redeposition off the Amazon produces terrigenous and bioclastic turbidite sequences with rates increasing, on the average, from 50 to 150 m/My. Small manganese nodules (coarse sand and small pebbles) are common in sediments associated with hiatuses at Sites 135 (Eocene-Miocene, Core SW1), 136 (Late Cretaceous- Miocene, Cores 3 to 6), and to a lesser extent at 141 (Middle Miocene-Pliocene, Core 7). Additional occurrences were noted in the pelagic clays at Site 137 (Late Cretaceous to Miocene). At 135-8 (Cenomanian) micro-nodules occur within a mixture of siltstone fragments, compressed planktonic foraminifera, fish debris, as well as chert pebbles and other redeposited components. Manganese concretions are generally younger than Turonian and are restricted to the predominantly oxidized part of the sequences, that is, where sediments are mostly red, brown, or yellow-colored.

Description: During Leg 24 three drilling sites were occupied in the Gulf of Aden (231, 232, 233), two in the Somali Basin (234, 235), and three in the western Indian Ocean (236, 237, 238). The location of these sites is shown in Figure 1; latitude, water depth, and penetration depth are indicated in Table 1. Figure 2 summarizes the lithologies and stratigraphy of all eight sites cored. In this chapter are included lithologic summaries for each of the sites. The sediments are then discussed in terms of their individual biogenic, terrigenous, volcanogenic, or authigenic components and their sedimentary structures. In a series of synthesis sections the hemipelagic, pelagic, and basal metaliferous sedimentary facies are discussed.

Description: Pelagic deposits are the dominant contributors to the sediment layers that blanket ridges and basaltic sea floor in deep basins. Among pelagic constituents, nannofossils undoubtedly are the predominant contributor, especially to Cenozoic chalk and ooze. Among Leg 25 sites, the most typical pelagic deposits are found in the Madagascar Basin (Site 245) including a clayey nanno chalk, bearing Fe-Mn oxides, resting directly on the basalt and overlain successively by a nanno chalk which is interlayered with chert and devitrified volcanic ash and a nearly pure nanno ooze. The lithologic sequence is capped by brown clay. Upper Cenozoic foram sand and foram nanno ooze were found on the Mozambique Ridge (Site 249) and particularly on the Madagascar Ridge (Site 246). Biogenic silica-rich facies are rare and mainly located near the top of the lowest latitude sites.

Description: DSDP Leg 26, is the fifth cruise of D/V Glomar Challenger in the Indian Ocean, and the first cruise of Phase III of the Deep Sea Drilling Project. The Indian Ocean is the smallest of the three major ocean basins but appears to be geologically the most complex. The sites drilled on Leg 26 were selected to try to elucidate a number of specific problems of both local and broad regional significance, as well as to add to the general knowledge of the area. In particular: a) To locate the oldest sediment in the Indian Ocean and thus possibly the date of the initial breakup of Gondwanaland (Sites 250, 256, 257); b) To determine the effects of the initiation of the Circumpolar Current on southern Indian Ocean sedimentation (Sites 250, 252, 256, 257, 258); c) To determine the history of spreading of the Southwest Branch of the Indian Ocean Ridge and the history of the crust and oceanic sedimentation in that general region (Sites 250, 251, 252).

Description: During Leg 27 five sites were drilled in the eastern Indian Ocean, four in abyssal plains near the western margin of Australia and one in the Timor Trough. Abyssal plain sediments are divided into two major units: (1) a lower, acoustically transparent layer of relatively uniform thickness draped over basaltic basement and (2) a horizontally layered sequence of highly variable thickness filling low areas on the surface of the transparent layer. The transparent layer, ranging in age from Upper Jurassic to Upper Cretaceous, consists chiefly of dark gray, siliceous clays and claystones with minor zeolitic clay and nannofossil ooze. Sedimentation rates are between 5 and 30 m/m.y. being highest in the Lower Cretaceous. Upper Cretaceous sediment are sparse or absent. The relatively high sedimentation rates for pelagic clay are probably due to the proximity of the Australian continent. The layered unit consists of calcareous oozes and lesser zeolitic clay and radiolarian ooze, all of Cenozoic age. Many of the oozes contain shallow-water foraminifers and graded sequences suggesting deposition by mass transport.

Description: Manganese nodules, micronodules, and crusts were encountered in surface sediments, and at depth, in 6 of the 10 sites drilled during DSDP Leg 29 south of New Zealand and Tasmania. Major concentrations of surface nodule pavements occur on and adjacent to the Campbell Plateau south of New Zealand, south of the Tasman Rise, and in the South Tasman Sea. These deposits are found on top of erosional unconformities, which span tens of millions of years and reflect scouring by strong bottom currents. Micronodules were also found at depth throughout most of these cores. Their occurrence apparently is dependent upon a number of environmental factors.

Description: The major purpose of Leg 31 was the scrutiny of tectonic, sedimentologic, volcanic, paleontologic, and paleooceanographic processes operative in arc-marginal basin complexes along with a deciphering of basin history. The 12 sites ultimately occupied during Leg 31 all yielded significant new data bearing on the nature and evolution of the West Philippine Basin, Shikoku Basin, and Sea of Japan. The major objective at sites 290 through 292 was to test the mode and age of origin of the West Philippine Sea with emphasis on the nature of the Central Basin Fault. Sites 294/295 were drilled far to the east of the Central Basin Fault zone in the thin sediment blanket covering deeper portions of the northeastern West Philippine Basin. The other sites were situated in the Sea of Japan.

Description: The northwestern Pacific Ocean is the largest expanse of old oceanic lithosphere, and so the principal theme of Leg 32 set by the Pacific Advisory Panel was the late Mesozoic history of the Pacific Ocean. The main scientific goals originally set for the leg were to: 1) Determine the development of the very deep sea floor of the western Pacific, including the nature of its basement rocks and the age, lithology, and fossil content of the sedimentary rocks overlying acoustic basement. 2) Establish standard mid-Mesozoic to Recent paleontological-biostratigraphic reference sections for the (present-day) northwest Pacific. 3) Determine the paleolatitude for a specific period of volcanicity on Koko Guyot of the Emperor Seamount Chain.

Description: The sea floor of the western Pacific is covered by five stratigraphic units: (l) an eastward thinning wedge of late Tertiary silty clay, primarily of volcanic origin, (2) a Cretaceous to Tertiary zeolitic red clay, (3) a Late Cretaceous to Tertiary chalk/chert sequence, (4) a Cretaceous clay, and (5) a basal chalk/chert sequence. The basal chalk was deposited on the young crust at the crest of the mid-oceanic ridge, while the upper chalk was deposited beneath the equator, and the abyssal clays were deposited in abyssal depths in mid latitudes. A kinematic model has been constructed that outlines the deposition of these units on growing crust, which not only was displaced westward away from the accretion center of the mid-oceanic ridge, but northward under the equator. The average northward component of motion for the Pacific plate has been 2 cm per year from 0 to 30 m.y. and 4.4 cm per year from 30 to 100 m.y. The deep-sea deposits of the Pacific are basically and systematically time transgressive. Claims of general synchroneity for either lithostratigraphy or acoustostratigraphy are rejected as inconsistent with both the drilling data and the kinematic model of Pacific pelagic stratigraphy. A few more well sampled holes in the ancient Pacific plate combined with an appropriately refined kinematic model should yield a 'rather detailed history of the Pacific plate since the Jurassic.

Description: In the summer of 1974, upon returning to Woods Hole from the Azores, the submersible Alvin had the opportunity to make brief dives on Corner Rise and the New England seamount chain. This was the first time man had directly viewed the expanse of the Earth between the Mid-Atlantic Ridge and the North of the American continent. Single dives were made on seven seamounts: Corner Rise and Nashville, Gilliss, Rehoboth, Manning, Balanus, and Mytilus.

Description: The Manihiki Plateau is an elevated area of shallow oceanic crust in the South Pacific; it was formed during Early Cretaceous time by profuse outpourings of basalt. DSDP Holes 317, 317A, and 317B, on which this account is based, are situated in a basinal area on the so called High Plateau, the shallowest part of the volcanic edifice, where depths range between 2000 and 3000 meters. The oldest sediments cored are Lower Cretaceous greenish-black volcaniclastics traversed by reddish-purple clay seams; these deposits commonly show evidence of redeposition, but the only possible shallow-water remains found are very rare bryozoan and echinoderm fragments.

Description: Dredging in the Danger Island Troughs, which divide the High and Western parts of the Manihiki Plateau, recovered several fresh pebbles of olivine tholeiite and tholeiite, a single pebble of highly altered gabbroic cumulate, and several dozen pebbles of altered variolitic basalt. Troughs suggests that at one time the troughs were the site of active faulting. A tectonic model for the evolution of the plateau, consistent with a fracture zone origin for the Danger Island Troughs, requires the formation of the Manihiki Plateau at a triple junction of the Pacific, Farallon, and Antarctic plates.

Description: This DSDP leg was originally conceived by the Antarctic Advisory Panel in order to investigate the geologic histories of the Scotia Arc and of the Argentine Basin. Site 326 (Drake Passage) was drilled in 3812 meters of water about 150 km southeast of Cape Horn. The main objective was to check the magnetic-reversal dating of the opening of Drake Passage by determining basement age. Site 327 is in 2400 meters of water on the western nose of the elevated eastern part of the Falkland Plateau, the Maurice Ewing Bank and was chosen to examine Southern Ocean shallow-water pre-Neogene biostratigraphy. Site 328, in 5103 meters of water in the Malvinas Outer Basin immediately to the east of the Falkland Plateau and to the south of the Falkland Fracture Zone, was chosen to examine correlatives of Argentine Basin acoustic reflectors, to obtain a deep-water southerly biostratigraphic section, and if possible, to date the underlying oceanic basement. Site 330, in 2626 meters of water at the western end of the elongate rise forming the eastern end of the Falkland Plateau, the Maurice Ewing Bank, was selected to elucidate the pre-Aptian history of the Falkland Plateau and to obtain a biostratigraphic section older than that cored at Sites 327 and 329.

Description: The Bauer Deep is the depression between the active East Pacific Rise on the west and the extinct Galapagos Rise on the east. The selection of Site 319 was based on a detailed survey of the Bauer Basin during Yaloc-13, Leg 3. Leg 3. It is in a basin about 8 km wide (east-west) at 13°OO.8'S, which is part of a broadly faulted zone on the low western flank of the Galapagos Rise. Site 320 and 321 where located in order to survey the Nazca plate. The objectives for Site 320 were (1) to core basalt continuously as deep as possible, with one and possibly two re-entries; (2) to determine the history of the eastern Nazca plate for the last 30 to 40 m.y., (3) to determine the effectiveness of the Peru-Chile Trench as a barrier to turbidity current dispersal. Site 321 is located on the eastern edge of the Nazca plate immediately south of the Mendafia Fracture Zone. The objectives for Site 321 were similar as those for Site 320.

Description: Because of its position between the North Atlantic and the Arctic oceans, its young age, small size, and diversity of geological structures, the Norwegian-Greenland Sea provided a unique target for deep drilling on Leg 38 of the Glomar Challenger. From studies of the sediments and basement rocks it was expected to gain insight particularly as to the following: 1) The tectonic framework and evolution of this area with special emphasis on the continental margins and on questions concerned with shifts of spreading axis and existence of foundered continental areas. 2) The youngest times of existence of land bridges between Eurasia and North America and the effect these land bridges had on water circulation and paleoclimates. 3) The date of the initiation of glaciation and dates of glacial advances and retreats. 4) Description of the Tertiary marine microfauna and microflora of the Norwegian-Greenland Sea, which are essentially unknown at present, and investigation of their similarity with microfauna and microflora from other areas.

Description: The data presented in this report is the result of investigations carried out by a number of laboratories on a suite of rocks dredged from the Mid - Atlantic Ridge at 45°N by F. Aura en to and K. S. Manchester during the three Bedford Institute cruises BI 19-66 Hudson, BI 22-68 Hudson, and BI 23-68 Theta.

Description: Scientists from the Woods Hole Oceanographic Institution, the U.S. Navy, the State University of New York at Albany, Wesleyan University, Oregon State University, Dalhousie University, and the Scripps Institution of Oceanography participated in the Cayman Trough expedition durieng 15 ALVIN dives in January and February 1976. The survey focused on a spreading center is a 150-km section of the plate boundary running across the floor of the Cayman Trough, where two tectonic plates are actually moving apart.

Description: Unlike most previous Deep Sea Drilling Project cruises, Leg 39 was not scientifically planned as a "theme" cruise, on which a number of sites are drilled to address a single scientific problem area, namely, to improve our knowledge of paleocirculation changes and the overall geologic history of the South Atlantic Ocean. This would be done along more specific objectives: 1) collect a biostratigraphic section on the Ceará Rise (Site 354), determine the nature and age of a prominent reflector there, and determine the nature and age of basement; 2) date basement between magnetic anomalies 32 and 33 in the Argentine Basin (Site 358), and 33 and 34 in the Brazil Basin (Site 355); obtain as complete sedimentary sections as time would permit at the Ceará Rise, Brazil Basin, the Argentine Basin and Sào Paulo Plateau (Site 356).

Description: The suite of gabbroic rocks collected by the DSRV ALVIN in 1976 and 1977 from the walls of the Mid-Cayman Rise spreading center were studied in detail to provide the best available data on plutonic rocks sampled directly from the ocean floor. The rock types studied include variably deformed and altered gabbros, orthopyroxene gabbros, olivine gabbros and troctolites, and a few amphibolites. Mineral chemical analyses suggest that the various rock types are representative of a fractionation trend from magnesian troctolites through olivine and clinopyroxene gabbros to iron-enriched orthopyroxene gabbros. Within many individual samples, the primary mineral phases are apparently chemically homogeneous despite sometimes considerable alteration, which suggests reequilibration after original crystallization. Variation in mineral-chemistry across the suite is larger than previously reported for ocean-floor gabbros; this may be due to the larger population of this study. The primary or secondary nature of plagioclase and amphibole must be distinguished in discussions of the igneous processes involved in the genesis of these rocks. In this suite, textural evidence is often inconclusive, and although sodic chemistry is assumed to indicate a secondary origin for plagioclase, no chemical indicator was found to apply to amphiboles. Many different deformation textures are observed in the samples, indicating considerable variation in the conditions of deformation within this slowly accreting ridge environment. Ductile features range from mechanical twins and bent crystals (low strain) to complete recrystallization with a well-developed foliation (high strain). Textures suggestive of cataclasis include zones .1-10 mm wide containing very fine, irregular grains; kinked and cracked grains, usually very undulose; and crosscutting fractures. These textures may occur separately, or next to or overprinting each other. Of the variables controlling the formation of deformation features, temperature and water pressure are most easily estimated. Minimum temperature during deformation is suggested by minimum temperature of formation of mineral assemblages unaffected by this deformation. This temperature is greater than 550°C (epidote-amphibolite facies) for the majority of features observed, although sampling may have introduced a bias away from lower temperature features. Observations suggest enhanced recrystallization where the primary mineralogy has been hydrated to a greater extent. Theoretically, confining pressure for the gabbroic rocks in this suite may have varied from about .3-.9kb; fluid pressure should have been within these limits. Based on mineralogical evidence, cataclastic and ductile textures developed at both high and moderate temperatures. This suggests that strain rates and/or pressure vary considerably within regions where rocks are hot as well as where rocks are cooler, and that after high-temperature deformation some rocks cooled quickly enough to prevent significant recrystallization while others cooled more slowly. These interpretations indicate that the Cayman plutonics were raised to their present position by motions which varied from place to place and time to time, and suggests that the structural history of plutonic.rocks formed at slowly accreting plate boundaries is highly variable and complex.

Description: The sites drilled on Leg 35 were selected to study the tectonic relationships and interactions between the Antarctic plate and the Antarctic Peninsula, the Scotia Arc, the southern Andes, and the Chile Ridge. Site 322 was drilled on the eastern end of the Bellingshausen Abyssal Plain where it is bounded by the Hero Fracture Zone to the northeast and the continental rise of Antarctica to the south. Site 323 was centrally located on the abyssal plain, about 30 miles west of the Eltanin Fracture Zone and about 150 miles north of the Antarctic continental rise. Site 324 was located on the gently sloping lower continental rise of Antarctica about 160 miles north of Thurston Island, the closest exposed land.

Description: Ranging in height from gentle hills of less than a meter to steep-sided giants of more than 20 m, the mounds of the Galapagos Rift are spectacular hydrothermal features. Their internal temperatures have been measured at up to 13°C above the bottom water temperature, and total heat flow (conducted plus convected) can be several hundred to several thousand times the normal oceanic values. Fluids, when they discharge from the mound, do so at a very slow rate and at temperatures probably quite near the bottom water temperature. The mounds are principally composed of iron silicates intermixed and incrusted with lesser amounts of manganese oxides. They are generally found in rows, in a uniformly sedimented area above faults or fractures in the crustal rocks which permit fluids to escape from a deep hydrothermal aquifer. The sediment blanket in some way alters the chemistry of the ascending thermal fluids and leads to the development of mounds. The mounds field, covering an area of at least 200 km2 and consisting of thousands of individual mounds, is probably less than 300,000 years old; and many of the mounds may be only a few tens of thousands of years old or less.

Description: From a structural and morphological point of view, the continental margin of southwestern Africa is a middle-aged "pull-apart" or "passive-type" margin which was initially created during the breakup of the supercontinent of Gondwanaland in the Mesozoic. The most important objective of the Leg 40 expedition was the attainment of strata laid down when the newly formed ocean was very young and only a few hundred kilometers wide. Site 361 was drilled at the fall of continental platform into the Cape Basin, to a sub-sea floor depth of 1314 meters and yielded sediments that range in age from upper Eocene to lower Aptian and possibly slightly older.

Description: he forty-first cruise of Glomar Challenger was devoted to the study of the evolution of the eastern basins of the North Atlantic, off the continental margin of West Africa. As the available data a the time was showing that most litho-stratigraphic units in the deep basins of the Atlantic had enough lateral extension, the drilling of a limited number of sites in key areas would allow for large-scale regional interpretation. One of the sites was loacted in the Cape Verde deep Basin (Site 367) while others were located in shallower waters such as, the Sierra Leone Rise (Site 366), the Cape Verde Rise (Site 368) or the Continental Slope off Spanish Sahara (Site 369).

Description: 2 nodules, one spherical, similar to 2 cm diameter form L. Alstern, Sweden the other saucer-shaped, similar to 2 cm thick from L. Oneida, New York were studied by using 228Ra and super(210)pb in order to measure accretion rates in the range 100-1000 mm/10 super(3) year. The deduced rates are 1.4 and 2.6 mm/ 10 super(3) year. Respectively. The author discuss the problems of how deep sea noducles stay at the sediment-water interface when the sediment around them is accumulating 1000 times faster than the nodules themselves.

Description: On cruises 10 and 15 of Academic Kurchatov (1971, 1973) at the Jan-Mayen Ridge, a large number of samples was obtained. Most of them contained sedimentary rocks. From their study, it is safe to assume that the rocks of the Jan-Mayen Ridge were, at first, subjected to subsidence to a considerable depth, and then uplifted to their contemporary position, by the ascending tectonic movements. Thus, the Jan-Mayen Ridge is in contrast to other Atlantic submarine ridges, not only in the sedimentary rock composition, but in the character of the tectonic movements.

Description: Leg 43 was planned to examine a wide variety of geological problems at numerous sites in the deep western North Atlantic basin. A variety of objectives were to be addressed on Leg 43,among these: 1) to investigate the sedimentary development of the North American basin, 2) to recover sediments containing late Mesozoic and Cenozoic fossils for biostratigraphic, paleobiogeographic, and paleoceanographic studies 3) to recover samples of basaltic basement from the smooth crest of the basement ridge associated with the northern part of the New England seamounts, 4) To examine the age and nature of volcanism on Bermuda and along the New England seamount chain, in order to test ideas on volcanic* origin such as the "hotspot" hypothesis, and to examine volcaniclastic lithofacies and assess the role of volcanic sources for certain North Atlantic sediments.

Description: Leg 42, Part 1 of the Deep Sea Drilling Project was scheduled to continue the geological exploration of the Mediterranean. The strategy was to search for areas where the Mediterranean Evaporite formation had been largely or completely removed by erosion, such is the case for Site 372. For Leg 42, Part 2, the project entered the Black Sea. In particular, Site 379 was located the central portion of the Black Sea.

Description: This paper summarizes the petrography and major element chemistry of basalt collected by R/V Atlantis II at 23 °N, and compare these data with published data for 22 °N and with the preliminary shipboard data for DSDP Sites 395 and 396, in order to define the regional petrologic setting of the Leg 45 basalts.

Description: A combined mineralogical, petrological, and geochemical study of altered basaltic rock samples of the upper oceanic crust from Hole 396B IPOD Leg 46. The hole was drilled on the west flank of the Mid-Atlantic Ridge, in anomaly 5 at about 23°N. The site is located in a sediment pond at a water depth of 4450 meters; 205 meters of pillow lavas intercalated with indurated ooze and one exceptionally thick lava unit (sill or flow?) were drilled.

Description: Leg 45 of the Deep Sea Drilling Project was the inaugural cruise of the International Phase of Ocean Drilling. Its primary scientific objective was to develop an understanding of the composition, structure, and origin of oceanic crust by drilling as deeply into it as technology would permit. The feasibility of drilling deep into the oceanic crust was demonstrated during Leg 37 when one hole was drilled 586 meters into basaltic volcanic rocks near the crest of the Mid-Atlantic Ridge at about 37 °N. The areas of principal interest for Leg 45 were survey areas AT-5, situated near 23 °N, 46 °W and AT-6 near 23 °N, 43°W. The two survey areas are on opposite sides of the Mid-Atlantic Ridge, south of the Kane fracture zone. During Leg 45, Holes 395 and 395A were drilled in survey area AT-5 and Hole 396, was drilled in survey area AT-6.

Description: The western part of the North Atlantic Ocean holds clues to some of the most intriguing questions in marine geology. But because the geologic problems are many and varied, the sites of Leg 44 were multipurpose in nature. In particular, some of the targets were : 1) the Blake Nose, a spur of the Blake Plateau, to determine the nature, age, and origin of reef-like structures recognized on seismic profiles and 2) the Blake Outer Ridge, a long low ridge of sediments that forms the eastern boundary of the Blake-Bahama Basin, where we hoped to study the stratigraphy and sample supposed clathrates.

Description: Unlike many cruises of the Deep Sea Drilling Project, Leg 48 was scientifically planned to drill a number of sites to systematically address the problems of passive margin evolution. Site 400 was drilled at the foot of the Meriadzek Escarpment of North Biscay in 4399 meters depth. The site was located in a half-graben forming part of a succession of tilted and rotated fault blocks near the continent/ocean boundary. Site 401 was situated on the planated edge of a tilted fault-block underlying the southern edge of the Meriadzek Terrace on the north Biscay margin. Site 402 was located on the upper slope of the northern continental margin of the Bay of Biscay. The main objectives were to establish the presence or absence of shallow water Upper Cretaceous beds, and to penetrate pre-Aptian synrift sediments and the upslope equivalent of the deep water Albian-Aptian carbonaceous mudstones penetrated at Hole 400A.

Description: Leg 49 of the International Phase of Ocean Drilling (IPOD) was designed with a wide spectrum of problems in mind. Topics investigated were (1) variation with time of mantle sources of spreading-center magmas, (2) aging of the volcanic layer, (3) degree of hydrothermal alteration and metamorphism of the volcanic layer, (4) lateral and vertical variation of the petrochemistry, magnetic properties, and structure of the volcanic layer, (5) north-south variability of spreading-center magmas through the North Atlantic, (6) initiation of glaciation during the late Pliocene, and (7) the influence of bottom currents originating at the Iceland-Faeroes Ridge on sediments of the ridge flank province of the western North Atlantic.

Description: Five of 34 dredge hauls taken in the Atlantic Ocean recovered a material tentatively described on shipboard as a salmon-colored clay. X-ray diffraction analysis showed the clay material to consist principally of palygorskite. Occurring with the palygorskite are quartz, calcite, and dolomite. It is suggested that the palygorskite (and sepiolite) is the result of chemical precipitation brought about by the reaction of hydrothermal solutions with sea water.

Description: The abyssal circulation of the Pacific Ocean east of the East Pacific Rise is deduced from hydrographic data, supported by a few direct current measurements. Two main flow paths are recognized: across the Chile Rise into the Chile Basin, and thence northward into the Peru Basin and Panama Basin; and eastward across the East Pacific Rise into the Guatemala Basin and into Bauer Basin. Transform fault troughs are important passages allowing flow across the rises, and the Peru-Chile Trench is the principal channel for inflow to the Peru and Panama basins. The deep water that flows across the East Pacific Rise near the equator has a similar temperature structure to that in the southern Chile Basin, but it is less saline and has lower oxygen concentrations. Along both flow paths the bottom waters become warmer, less saline, and less oxygenated as a result of vertical mixing (intensified near sills), geothermal heating (concentrated at active spreading centers) and in situ decay of organic matter (especially beneath productive surface waters). The regional pattern of abyssal circulation may partly control the distribution of metalliferous pelagic sediments (including both fine-grained precipitates and manganese nodules) and the rates of dissolution of calcareous sediments. Where the deep thermohaline flow is accelerated in narrow passages between basins it has deeply eroded the sea floor and transports sediment as bed load. Steady currents measured in one of these passages exceeded 30 cm/s.

Description: 35 km either side of the Pacific-Cocos spreading axis at 846'N, on crust 0.6 x 10SUP-6 years old, a pair of small seamounts rises 1.4 km above the faulted terrain of young abyssal hills. A high-resolution traverse made with the sonars and cameras of a deeply towed vehicle shows that the seamounts are inactive volcanoes, with concave side slopes that steepen upwards to 30, and then abruptly flatten at 2-4 km wide summits. Ledges of pillow basalt outcrop on the lower slopes, and form some talus slopes, but the superficial rock of the upper slopes appear to be mainly hyaloclastite. A transponder-navigated deep-tow survey at the summit area of the eastern seamount mapped an asymmetric caldera containing 3 pit craters, which have vertical walls and flat floors. Dredging across the caldera floor recovered hyaloclastite, angular fragments of primitive tholeiite, and manganese nodules. The paired seamounts probably had a common origin at a 'hot spot' on the spreading axis; continued to grow after they were split by sea-floor spreading; and became extinct and suffered summit collapse after they spread too far from their magma source.

Description: Examination of the surface of freshly collected ferromanganese nodules by scanning electron microscopy revealed the presence of microcolonies of rod- and coccus-shaped bacteria which appeared to be anchored to the nodule surface by slime. The attachment of microcolonies by slime to the surface of freshly collected nodules argues against their being contaminants introduced during nodule collection or processing. These results corroborate cultural and biochemical detection of bacteria on ferromanganese nodules.

Description: Various types of rocks consisting of plagioclase basalts, olivine basalts, pyroxene basalts, picritic basalts and volcanoclastics were found in the Rift Valley between 36°52'N and 36°47'N in the Atlantic Ocean. Palagonite and manganese are the main coating materials encountered on the chilled margins of the pillow-lava fragments. Palagonite is often associated with montmorillonite and chlorite. The thickness of palagonite coating the chilled margins increases in the fragments found from the innerfloor axis towards the walls of the Rift Valley. There is a linear correlation between the thickness of palagonite and that of the manganese encrustation. Considering a rate of manganese and palagonite accumulation of about 3my/10**3 year it is speculated that the age of a hill located near the axis of the inner floor near 36°50'N is between 3,000 and 12,000 years. The relative age of the inner floor near the intersection of the Rift Valley walls is less than 120,000 years. The specimens having a thicker manganese and palagonite crust located at 4-6 km away from the inner floor axis are 130,000–482,000 years old.

Description: The 286 site is located in the gap between the North and South New Hebrides trenches near the foot of the slope down from Malekula (100 km west of the island) and 370 km north of Mare in the Loyalty Island. The main objectives at the site were: 1) To determine when detritus was first shed into this basin from Malekula and thereby determine when the trench was destroyed and whether the island has moved into its present position in relatively recent time. 2) To determine the time of generation of the sea floor and compare it with that of the South Fiji Basin The Ontong-Java Plateau is underlain by a region of unusual oceanic crust that has an estimated maximum thickness of 40 km. Site 288 was located on the eastern flank of the plateau with the hope that the nature of the basement of the plateau could be determined.

Description: Quantitative and qualitative chemical analyses were performed on fourteen manganese nodules and crusts from the Waho Shelf. The analyses showed that submarine weathering has leached several elements, notably Si02, A1203, Na20, CaO and MnO from the hydrated glass surrounding the basaltic seeds of the nodules. The altered glass was enriched in Ti02, MgO, K2O and total Fe. The manganese bands formed on the altered glass were further depleted in Si02, Al203, and similar to the hydrated glass in Na2O and CaO content. The manganese-enriched zones also showed higher TiO2 and NiO than the basaltic seeds, and higher total Fe than pelagic nodules from the North Pacific. Qualitative measurement of Cu, Ni, and Co, showed relative enrichment in the manganese bands. A proposed model for manganese accretion in the Waho Shelf incorporates local submarine weathering of basalts, redistribution of Mn in marine sediments, and an influx of Mn "rain" on the sea floor.

Description: Detailed mapping of manganese deposits in the Kauai Channel and on the Waho Shelf adjacent to the northwest corner of Oahu is near completion. Manganese crusts and nodules are concentrated on submarine terraces between 800 and 2400 meters deep. Similarities In the geomorphology and sedimentary conditions where extensive manganese deposits are present suggest that these are primary factors controlling manganese distribution in the Hawaiian Archipelago. This information may be useful for guiding future surveys, and the technology developed for studiesiIn the Hawaiian Archipelago may have application to other areas of high topographic relief and low sediment thickness (i.e., seamounts, fracture zones, fault scarps, ridges, etc.).

Description: In Costa Rica the manganese deposits are an integral part of the Nicoya ophiolite complex. They contain both primary mineralization and, due to weathering, small residual concentrations. The most common manganese minerals in surface outcrops are psilomelane and pyrolusite. Most of them exist in jasper bodies often in a form of breccia in contact with underlaying basalt. In some instances stratiform manganese-oxide crusts and nodule deposits cap jasper bodies and stratabound deposits being overlain by radiolarites.

Description: Fragments of a hydrothermal deposit, partly moulded on pieces of basalt lava, were dredged from the edge of the median valley in the centre of the Gulf of Aden. The deposit consists of two main components, manganese oxide in the form of spongy brown to hard black lumps and coatings, and friable green massive smectite. There are smaller amounts of an iron-oxide component, and mixed manganese-oxide-smectite material. Contents of the less mobile trace elements in the smectite are too low for it to have formed by alteration of basalt glass, and it is interpreted as a direct precipitate from hydrothermal solution. None of the components is enriched in Cu or Zn, or contains appreciable amounts of sulphur. If there are sulphides in this deposit, they must lie beneath the parts sampled.

Description: This report presents barrel descriptions of deep-sea sediment cores obtained by the Hawaii Institute of Geophysics on cruises of the R/V Mahi during 1970 in the western Pacific Ocean. Many of the cores provided useful preliminary observations for later detailed surveys of drilling sites for the Deep-Sea Drilling Project in the southwest Pacific.

Description: One of the main objectives of the International Phase of Ocean Drilling (IPOD) of the Deep Sea Drilling Project was to determine the geological, geochemical, and geophysical character of ocean crust formed at mid-ocean spreading ridges. A series of drill holes along the Mid-Atlantic Ridge (MAR), from near Iceland south to approximately 22°N latitude, was planned to compare the crust being generated near an anomalous ridge (Iceland) with that originating near a normal slow-spreading ridge (22°N). At the same time, a series of holes in near zero-age crust at 22 °N was planned along a "flow line" (a transect parallel to local fracture zones) trending west into increasingly older crust, eventually extending the sampling to crust of apparent Jurassic date off the eastern United States coast. This age-transgressive transect was designed to test the evolution of crust formed at one point in the spreading ridge. The intersection of these two series of holes was designated Atlantic Site 5 and was positioned on the upper western flank of the Mid Atlantic Ridge near 22 °N latitude, as close as possible to the spreading ridge crest. The R/V Kana Keoki conducted a detailed 22-day survey of Atlantic Site 5 during Cruise 74-01-01, Leg 7 prior to the DSDP Leg45 was conducted.

Description: This report represents the first in a projected series reporting core descriptions and their physical properties, to be made available through routine core handling procedures instituted at the Hawaii Institute of Geophysics in 1968 to keep pace with the capability to take long (120-foot) piston cores from the University of Hawaii's R/V MAHI. The data reported herein cover sediment cores collected during 1967, 1968, and 1969 in the region of the Solomon Islands and the Darvir. Rise, and along the central portion of the Murray Fracture Zone.

Description: This report presents megascopic descriptions of deep-sea sediment cores obtained by personnel of the Hawaii Institute of Geophysics on cruises of the R/V Kana Keoki in the eastern and western Pacific Ocean during the year 1972.