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  • Other Sources  (39)
  • AGU  (39)
  • 2000-2004  (10)
  • 1985-1989  (29)
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  • 1
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    Earth's Core: Dynamics, Structure, Rotation (2003)
    AGU
    In:  Washington, D.C., 277 pp., AGU, vol. 31, no. 3, pp. 2-203, (ISBN 0-87590-533-1)
    Details
    Publication Date: 2003
    Keywords: earth Core ; GeodesyY ; Earth rotation ; Handbook of geophysics ; Handbook of geodesy
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    BIBLIOGRAPHY SEISMOLOGY
  • 2
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    Crustal Structure of the Ocean-Continent Transition at Flemish Cap: Seismic Refraction Results (2003)
    AGU
    In:  Journal of Geophysical Research: Solid Earth, 108 (B11). p. 2531.
    Details
    Publication Date: 2020-07-23
    Description: We conducted a seismic refraction experiment across Flemish Cap and into the deep basin east of Newfoundland, Canada, and developed a velocity model for the crust and mantle from forward and inverse modeling of data from 25 ocean bottom seismometers and dense air gun shots. The continental crust at Flemish Cap is 30 km thick and is divided into three layers with P wave velocities of 6.0–6.7 km/s. Across the southeast Flemish Cap margin, the continental crust thins over a 90-km-wide zone to only 1.2 km. The ocean-continent boundary is near the base of Flemish Cap and is marked by a fault between thinned continental crust and 3-km-thick crust with velocities of 4.7–7.0 km/s interpreted as crust from magma-starved oceanic accretion. This thin crust continues seaward for 55 km and thins locally to ~1.5 km. Below a sediment cover (1.9–3.1 km/s), oceanic layer 2 (4.7–4.9 km/s) is ~1.5 km thick, while layer 3 (6.9 km/s) seems to disappear in the thinnest segment of the oceanic crust. At the seawardmost end of the line the crust thickens to ~6 km. Mantle with velocities of 7.6–8.0 km/s underlies both the thin continental and thin oceanic crust in an 80-km-wide zone. A gradual downward increase to normal mantle velocities is interpreted to reflect decreasing degree of serpentinization with depth. Normal mantle velocities of 8.0 km/s are observed ~6 km below basement. There are major differences compared to the conjugate Galicia Bank margin, which has a wide zone of extended continental crust, more faulting, and prominent detachment faults. Crust formed by seafloor spreading appears symmetric, however, with 30-km-wide zones of oceanic crust accreted on both margins beginning about 4.5 m.y. before formation of magnetic anomaly M0 (~118 Ma).
    Type: Article , PeerReviewed
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  • 3
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    Structure of the SE Greenland margin from seismic reflection and refraction data: Implications for nascent spreading center subsidence and asymmetric crustal accretion during N Atlantic opening (2003)
    AGU
    In:  Journal of Geophysical Research: Solid Earth, 108 (B5). p. 2269.
    Details
    Publication Date: 2020-07-23
    Description: Seismic reflection and refraction data from the SE Greenland margin provide a detailed view of a volcanic rifted margin from Archean continental crust to near-to-average oceanic crust over a spatial scale of 400 km. The SIGMA III transect, located ∼600 km south of the Greenland-Iceland Ridge and the presumed track of the Iceland hot spot, shows that the continent-ocean transition is abrupt and only a small amount of crustal thinning occurred prior to final breakup. Initially, 18.3 km thick crust accreted to the margin and the productivity decreased through time until a steady state ridge system was established that produced 8–10 km thick crust. Changes in the morphology of the basaltic extrusives provide evidence for vertical motions of the ridge system, which was close to sea level for at least 1 m.y. of subaerial spreading despite a reduction in productivity from 17 to 13.5 km thick crust over this time interval. This could be explained if a small component of active upwelling associated with thermal buoyancy from a modest thermal anomaly provided dynamic support to the rift system. The thermal anomaly must be exhaustible, consistent with recent suggestions that plume material was emplaced into a preexisting lithospheric thin spot as a thin sheet. Exhaustion of the thin sheet led to rapid subsidence of the spreading system and a change from subaerial, to shallow marine, and finally to deep marine extrusion in ∼2 m.y. is shown by the morphological changes. In addition, comparison to the conjugate Hatton Bank shows a clear asymmetry in the early accretion history of North Atlantic oceanic crust. Nearly double the volume of material was emplaced on the Greenland margin compared to Hatton Bank and may indicate east directed ridge migration during initial opening.
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  • 4
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    On the generation of microseismics observed in north and central Europe (2003)
    AGU
    In:  Journal of Geophysical Research: Solid Earth, 108 (B10). p. 2506.
    Details
    Publication Date: 2020-07-23
    Description: Microseism recordings from four European broadband stations and from three seismic arrays in Scotland, Norway, and Germany are compared with model wave data of the oceanic wave field in the North Atlantic and local ocean wave data from the Norwegian coast at 60�N, both measured during February–March 2000. Two approaches have been tested to locate generation areas of microseismic energy: a new amplitude correlation technique and beam backprojection from the three seismic arrays. Both techniques reveal that the main generation areas are located in specific regions off the coast of Southwest Norway and North Scotland. Seismic stations distant from these generation areas record a superposition of seismic energy from different source regions. Those close to a specific source region also show a high correlation with it. Both techniques give upper limits for the extent of the generation area of the strongest storm on 6/7 March at the southwest Norwegian coast of about 500 km. By using marine X-band radar measurements of the two-dimensional wave height spectrum, we estimate that the relative change of the extension of the generation area off the coast of southwest Norway during several storms is less than a factor of 3. This indicates that the size of the generation area is controlled by static features as coastline or bathymetry, and not by the extent of the storms. Microseism energy appears to be mainly controlled by the wave height in distinct and identifiable generation regions, so that the wave climate in these regions can be studied using historical records of microseisms.
    Type: Article , PeerReviewed
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  • 5
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    Plate Boundary Zones (2002)
    AGU
    In:  Washington, D.C., vii + 425 pp., AGU, vol. 30, no. Publ. No. 12, pp. 95-104, (ISBN 0-87590-532-3, AGU Code: GD0305323)
    Details
    Publication Date: 2002
    Keywords: Textbook of geophysics ; Plate tectonics ; Seismicity ; Seismology
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    BIBLIOGRAPHY SEISMOLOGY
  • 6
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    The global moment rate distribution within plate boundary zones (2002)
    AGU
    In:  Bull., Polar Proj. OP-O3A4, Plate Boundary Zones, Washington, D.C., AGU, vol. 30, no. 2, pp. 173-190, (ISBN 0-87590-532-3, AGU Code: GD0305323)
    Details
    Publication Date: 2002
    Keywords: Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Strain ; GSRM ; map ; Paleomagnetism ; Plate tectonics ; Seismicity
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    BIBLIOGRAPHY SEISMOLOGY
  • 7
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    Radiogenic isotopes: Tracers of past ocean circulation and erosional input (2002)
    AGU
    In:  Reviews of Geophysics, 40 (1).
    Details
    Publication Date: 2020-06-03
    Description: The radiogenic isotope composition of dissolved trace metals in the ocean represents a set of relatively new and not yet fully exploited tracers with a large potential for oceanographic and paleoceanographic research on timescales from the present back to at least 60 Ma. The main topic of this review are those trace metals with oceanic residence times on the order of or shorter than the global mixing time of the ocean (Nd, Pb, Hf, and, in addition, Be). Their isotopic composition in the ocean has varied as a function of changes in paleocirculation, source provenances, style and intensity of weathering on the continents, as well as orogenic processes. The relative importance of these processes for each trace metal is evaluated, which is a prerequisite for reliable interpretation of their time series in terms of changes in paleocirculation or weathering inputs. This analysis of processes includes a discussion of the long-term isotopic evolution of Sr and Os, which are well mixed in the ocean and have thus not been influenced by circulation changes. The radiogenic isotope evolution of those trace metals with intermediate oceanic residence times can be used as paleoceanographic proxies to reconstruct paleocirculation and weathering inputs into the ocean. This is demonstrated by studies from different ocean basins, mainly carried out on ferromanganese crusts, which show that radiogenic trace metal isotopes provide important new insights and can complement results obtained by other well-established paleoceanographic tracers such as carbon isotopes.
    Type: Article , PeerReviewed
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  • 8
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    Magma flow regimes in sills deduced from Ar isotope systematics of host rocks (2001)
    AGU
    In:  Journal of Geophysical Research: Solid Earth, 106 (B3). pp. 4017-4036.
    Details
    Publication Date: 2020-07-23
    Description: The best place to seek evidence of the style of past magma flow through a conduit is in the country rock. Heat flow has been studied in country rock adjacent to two Tertiary dolerite sills intruding the Caledonian schists and quartzites, on the Isle of Mull, Scotland. Radiogenic 40Ar loss within mica grains in the thermal aureoles of the intrusions has been measured at high spatial resolution using the Ultra-Violet Laser Ablation Micro-Probe, to discriminate between a history of prolonged magma flow, a history of conductive cooling following laminar flow, and instantaneous emplacement of the intrusions. The 40Ar/39Ar mica data and thermal modeling suggest that a prolonged period of magma flow of 3–5 months resulted in extensive argon loss from the micas, country rock melting, and mineral breakdown adjacent to a 6-m sill. These features were absent from the wall rocks of a smaller 2.7-m-thick sill, which exhibited even less argon loss than might have been predicted for an instantaneous intrusion. If the heat loss from the 6-m sill observed in one locality had been repeated along its length, it would have formed an important magma conduit to the Mull volcano, but dolerite is not a common flow composition on Mull. If on the other hand, the heat loss from the sill varies along strike, it constitutes strong evidence for channelling and heterogeneous flow within the sill.
    Type: Article , PeerReviewed
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  • 9
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    Stability and variability of the thermohaline circulation in the past and future: A study with a coupled model of intermediate complexity (2001)
    AGU
    In:  Oceans and rapid past and future climate changes: North-South connections
    Details
    Publication Date: 2022-03-21
    Type: info:eu-repo/semantics/bookPart
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    CITATION PIK
  • 10
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    Stability and variability of the thermohaline circulation in the past and future: A study with a coupled model of intermediate complexity (2000)
    AGU
    In:  Oceans and rapid past and future climate changes: North-south connections
    Details
    Publication Date: 2022-03-21
    Type: info:eu-repo/semantics/bookPart
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  • 11
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    Slow Deformation and Transmission of Stress in the Earth (1989)
    AGU
    In:  Washington D. C., AGU, vol. 4, no. 3, pp. 2-203, (ISBN: 3-540-41598-X)
    Details
    Publication Date: 1989
    Keywords: Plate tectonics ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; Stress ; Vanicek
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    BIBLIOGRAPHY SEISMOLOGY
  • 12
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    Volcanic Hazards (1989)
    AGU
    In:  Washington D. C., AGU, vol. 3, no. ALEX(01)-FR-77-01, AFTAC Contract F08606-76-C-0025, pp. 329, (ISBN 1-903544-06-8)
    Details
    Publication Date: 1989
    Keywords: Textbook of geology ; Volcanology ; Earthquake hazard
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    BIBLIOGRAPHY SEISMOLOGY
  • 13
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    Deep Structure and Past Kinematics of Accreted Terranes (1989)
    AGU
    In:  Washington D. C., AGU, vol. 5, no. XVI:, pp. 1-14, (ISBN 0-89871-521-0)
    Details
    Publication Date: 1989
    Keywords: Earth model, also for more shallow analyses ! ; Plate tectonics ; Geol. aspects ; Deep seismic sounding (espec. cont. crust)
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    BIBLIOGRAPHY SEISMOLOGY
  • 14
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    Mechanical models of tilted block basins (1989)
    AGU
    In:  Bull., Polar Proj. OP-O3A4, Origin and Evolution of Sedimentary Basins and Their Energy, Washington, D.C., AGU, vol. 48, no. 4, pp. 65-71, (ISBN 0080419208)
    Details
    Publication Date: 1989
    Keywords: Geol. aspects ; Modelling ; Crustal deformation (cf. Earthquake precursor: deformation or strain) ; 8110 ; Tectonophysics ; Continental ; tectonics ; 8165 ; Structural ; geology ; (crustal ; structure ; and ; mechanics) ; 8194 ; Instruments ; and ; techniques
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    BIBLIOGRAPHY SEISMOLOGY
  • 15
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    Fundamental in Geostatistics in Five Lessons (1989)
    AGU
    In:  Washington D. C., AGU, vol. 8, no. XVI:, pp. 1-14, (ISBN: 0-387-30752-4)
    Details
    Publication Date: 1989
    Keywords: Data analysis / ~ processing ; Statistical investigations
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    BIBLIOGRAPHY SEISMOLOGY
  • 16
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    Evolution of Mid Ocean Ridges (1989)
    AGU
    In:  Washington D. C., AGU, vol. 8, no. Publ. No. 12, pp. 9, (3-540-24165-5, XXVI + 228 p.)
    Details
    Publication Date: 1989
    Keywords: Earth model, also for more shallow analyses ! ; Plate tectonics
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    BIBLIOGRAPHY SEISMOLOGY
  • 17
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    Shear-wave polarizations at the Anza seismic array (1989)
    AGU
    In:  AGU Spring Meeting, S22A-13, Baltimore, AGU, vol. 11, no. CUED/C/Mats/Tr 51, pp. 1414-1415
    Details
    Publication Date: 1989
    Keywords: Seismic networks ; Seismic arrays ; Filter- ; Polarization ; Shear waves
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    BIBLIOGRAPHY SEISMOLOGY
  • 18
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    Elastic Properties and Equations of State (1988)
    AGU
    In:  Washington, D.C., AGU, vol. Developments in Petroleum Science vol. 15B, no. Publ. No. 12, pp. 9, (ISBN: 3-540-31080-0)
    Details
    Publication Date: 1988
    Keywords: Handbook of physics ; Handbook of mineralogy ; Physical properties of rocks ; Mineralogy
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    BIBLIOGRAPHY SEISMOLOGY
  • 19
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    Formation of anisotropy in upper mantle peridotites - A review (1987)
    AGU
    In:  Bull., Polar Proj. OP-O3A4, Composition, Structure and Dynamics of the Lithosphere-Asthenosphere System, Washington, D.C., AGU, vol. 16, no. Subvol. a, pp. 111-123, (ISBN 0080419208)
    Details
    Publication Date: 1987
    Keywords: Review article ; Anisotropy ; Physical properties of rocks
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    BIBLIOGRAPHY SEISMOLOGY
  • 20
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    Reflection Seismology: A Global Perspective (1986)
    AGU
    In:  Washington D. C., AGU, vol. 1, pp. 6322, (ISBN 0-521-79203-7)
    Details
    Publication Date: 1986
    Keywords: Textbook of geophysics ; Seismics (controlled source seismology) ; Earth model, also for more shallow analyses !
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    BIBLIOGRAPHY SEISMOLOGY
  • 21
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    Reflection Seismology: The Continental Crust (1986)
    AGU
    In:  Washington D. C., AGU, vol. 14, pp. 6322, (ISBN 0-521-79203-7)
    Details
    Publication Date: 1986
    Keywords: Textbook of geophysics ; Seismics (controlled source seismology) ; Earth model, also for more shallow analyses ! ; Reflection seismics
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    BIBLIOGRAPHY SEISMOLOGY
  • 22
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    Earthquake repeat time and average stress drop (1986)
    AGU
    In:  Washington D.C., AGU, vol. 6, no. XVI:, pp. 227-235, (ISBN 3-342-00685-4)
    Details
    Publication Date: 1986
    Keywords: Stress ; Earthquake precursor: statistical anal. of seismicity ; Source parameters ; Stress drop
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    BIBLIOGRAPHY SEISMOLOGY
  • 23
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    Slip on an impermeable fault in a fluid-saturated rock mass (1986)
    AGU
    In:  Washington D.C., AGU, vol. 6, no. Publ. No. 12, pp. 81-89, (ISBN 0-444-50971-2)
    Details
    Publication Date: 1986
    Keywords: Rock mechanics ; Fluids ; Source
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    BIBLIOGRAPHY SEISMOLOGY
  • 24
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    Fracture of a single asperity on a finite fault: A model for weak earthquakes (1986)
    AGU
    In:  Professional Paper, Earthquake Source Mechanics, Washington, D.C., AGU, vol. 6, no. 16, pp. 91-96, (ISBN 1-4020-1729-4)
    Details
    Publication Date: 1986
    Keywords: Earthquake precursor: prediction research
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    BIBLIOGRAPHY SEISMOLOGY
  • 25
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    Small and large earthquakes: The effects of the thickness of the seismogenic layer and free surface (1986)
    AGU
    In:  Bull., Open-File Rept., Earthquake Source Mechanics, Maurice Ewing Ser., Washington D.C., AGU, vol. 6, no. 16, pp. 209-216, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1986
    Keywords: Seismicity ; Subduction zone ; scaling ; Magnitude ; seismic Moment ; nokms
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    BIBLIOGRAPHY SEISMOLOGY
  • 26
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    Rupture interaction with fault jogs (1986)
    AGU
    In:  Bull., Open-File Rept., Earthquake Source Mechanics, Maurice Ewing Ser., Washington D.C., AGU, vol. 6, no. 16, pp. 157-167, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1986
    Keywords: Fracture ; Fault zone ; Source
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    BIBLIOGRAPHY SEISMOLOGY
  • 27
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    Earthquake Source Mechanics (1986)
    AGU
    In:  Washington, D.C., 341 pp., AGU, vol. 231, no. 3, pp. 2-203, (ISBN 0-470-02298-1)
    Details
    Publication Date: 1986
    Keywords: Earthquake precursor: prediction research
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  • 28
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    On the elastic contact modeling of faults with variable stiffness (1986)
    AGU
    In:  Washington D.C., AGU, vol. 6, no. XVI:, pp. 65-70, (ISBN: 3486274473, 2. Auflage 2004, xxiv, 244 Seiten)
    Details
    Publication Date: 1986
    Keywords: Friction ; Fault zone ; Elasticity
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    BIBLIOGRAPHY SEISMOLOGY
  • 29
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    Rupture processes in the presence of creep zones (1986)
    AGU
    In:  Washington D.C., AGU, vol. 6, no. 22, pp. 71-80, (ISBN 0-87590-422-X)
    Details
    Publication Date: 1986
    Keywords: Fracture ; Inelastic ; Fault zone ; Source mechanics
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    BIBLIOGRAPHY SEISMOLOGY
  • 30
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    Low stress-drop earthquakes in the light of new data from the Anza, California telemetered digital array (1986)
    AGU
    In:  Professional Paper, Earthquake Source Mechanics, Washington, D.C., AGU, vol. 6, no. 16, pp. 237-245, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1986
    Keywords: Earthquake precursor: prediction research ; Stress drop ; Seismic arrays ; Source parameters
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    BIBLIOGRAPHY SEISMOLOGY
  • 31
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    Long-range seismic refraction profiles in Europe (1986)
    AGU
    In:  Bull., Polar Proj. OP-O3A4, Reflection Seismology: A Global Perspective, Washington, D.C., AGU, vol. 13, no. Subvol. a, pp. 167-182, (ISBN 0080419208)
    Details
    Publication Date: 1986
    Keywords: Review article ; Deep seismic sounding (espec. cont. crust) ; Refraction seismics ; Muller
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    BIBLIOGRAPHY SEISMOLOGY
  • 32
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    The fractal geometry of faults and faulting (1986)
    AGU
    In:  Bull., Open-File Rept., Earthquake Source Mechanics, Washington D. C., AGU, vol. 6, no. 16, pp. 147-155, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1986
    Keywords: FractureT ; Fault zone ; Geol. aspects
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    BIBLIOGRAPHY SEISMOLOGY
  • 33
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    A discussion of the depth extent of rupture in large continental earthquakes (1986)
    AGU
    In:  Bull., Open-File Rept., Earthquake Source Mechanics, Washington, D.C., AGU, vol. 6, no. 1, pp. 131-145, (ISBN 1-86239-165-3, vi + 330 pp.)
    Details
    Publication Date: 1986
    Keywords: Earthquake ; Stress ; Geothermics ; CRUST ; Inelastic ; HGROSSER ; FROTH
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    BIBLIOGRAPHY SEISMOLOGY
  • 34
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    Structural and volcanic expression of a fast slipping ridge-transform-ridge-plate boundary: Sea MARC I and photographic surveya at the Clipperton transform fault (1986)
    AGU
    In:  Journal of Geophysical Research: Solid Earth, 91 (B3). pp. 3469-3488.
    Details
    Publication Date: 2020-07-23
    Description: A high-resolution near-bottom survey has been conducted of the Clipperton transform fault and adjoining segments of the East Pacific Rise (EPR), using the Sea MARC I side-looking sonar system and the Lamont-Doherty Geological Observatory Olympus-based camera system. The transform fault zone (TFZ) is a narrow, well-defined belt of transform-parallel lineaments, which varies along strike from a single, sharp-edged notch to a complex band of subparallel lineaments up to 1 km wide. The TFZ is set within a 5-km-wide band of unusually fine-grained side scan texture, which could indicate nonbasaltic seafloor and/or pervasively sheared and mass-wasted basaltic crust The fine-grained swath is surrounded by constructional volcanic terrain with no hint of strike-slip motion; this observation puts an upper limit of 5 km on the extent of lateral migration of the TFZ in the last 1.5 m.y. Both ridge transform intersections (RTIs) are dominated by bathymetric highs located on the old plate opposite the spreading center. A mantling of fresh-looking constructional volcanic terrain on side scan images suggests that the highs are built in part by recent extrusive and intrusive volcanism; thermal expansion may also play a part. The EPR south of Clipperton has recently experienced extrusion of high effusion rate basalts, burial of faults and fissures by lava flows, and development of vigorous hydrothermal circulation. On the EPR north of Clipperton, the axial zone of faults and fissures tapers toward the transform fault; this may reflect a change in the shape or size of the underlying shallow level magma feeders as a function of distance from the site of magma upwelling or distance toward the transform fault.
    Type: Article , PeerReviewed
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  • 35
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    A model of the seasonal cycle in the tropical Atlantic Ocean (1986)
    AGU
    In:  Journal of Geophysical Research: Oceans, 91 (C12). pp. 14192-14206.
    Details
    Publication Date: 2020-07-23
    Description: In the western tropical Atlantic, seasonal variations in the surface winds and in the ocean are dominated by an annual harmonic. A simulation with a general circulation model indicates that the response in the western side of the basin is an equilibrium one practically in phase with the local winds. It includes the following: large vertical excursions of the thermocline that have a 180° change in phase across 8°N approximately; a change in the direction of the North Brazilian Coastal Current, which flows continuously along the coast between December and May but which veers offshore near 5°N to feed the North Equatorial Countercurrent during the other months; and a seasonal reversal of the countercurrent. To the east of 30°W, seasonal changes in the model have a prominent semiannual harmonic in phase with the local winds but only partially attributable to forcing at that frequency. The transients excited by the abrupt intensification of the southeast tradewinds in May happen to have a phase essentially the same as that of the semiannual forcing. These transients decay by the end of the calendar year, so that the seasonal cycle that starts with the intensification of the winds in May can be treated as an initial value problem as far as the upper ocean, above the thermocline, is concerned. The winds along the equator determine the response of the surface equatorial layer in the Gulf of Guinea but play a minor role in the seasonal upwelling along the coast near 5°N. That upwelling is strongly influenced by changes in both components of the wind, and in the curl of the wind, over the Gulf of Guinea.
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  • 36
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    Isotopic versus micrometeorologic ocean CO2 fluxes: A serious conflict (1986)
    AGU
    In:  Journal of Geophysical Research: Oceans, 91 (C9). pp. 10517-10527.
    Details
    Publication Date: 2020-07-23
    Description: Eddy correlation measurements over the ocean give CO2 fluxes an order of magnitude or more larger than expected from mass balance measurements using radiocarbon and radon 222. In particular, Smith and Jones (1985) reported large upward and downward fluxes in a surf zone at supersaturations of 15% and attributed them to the equilibration of bubbles at elevated pressures. They argue that even on the open ocean such bubble injection may create steady state CO2 supersaturations and that inferences of fluxes based on air-sea pCO2 differences and radon exchange velocities must be made with caution. We defend the global average CO2 exchange rate determined by three independent radioisotopic means: prebomb radiocarbon inventories; global surveys of mixed layer radon deficits; and oceanic uptake of bomb-produced radiocarbon. We argue that laboratory and lake data do not lead one to expect fluxes as large as reported from the eddy correlation technique; that the radon method of determining exchange velocities is indeed useful for estimating CO2 fluxes; that supersaturations of CO2 due to bubble injection on the open ocean are negligible; that the hypothesis that Smith and Jones advance cannot account for the fluxes that they report; and that the pCO2 values reported by Smith and Jones are likely to be systematically much too high. The CO2 fluxes for the ocean measured to date by the micrometeorological method can be reconciled with neither the observed concentrations of radioisotopes of radon and carbon in the oceans nor the tracer experiments carried out in lakes and in wind/wave tunnels.
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  • 37
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    Heat flow in southernmost California and the origin of the Salton Trough (1985)
    AGU
    In:  Journal of Geophysical Research: Solid Earth, 90 (B8). p. 6709.
    Details
    Publication Date: 2020-07-23
    Description: Heat flow in the Imperial Valley and adjacent crystalline rocks is very high (∼140 mW m−2). Gravity and seismic studies suggest the crust is about 23.5 km thick with the lower half composed of gabbro and the upper fourth composed of low-density sediments. Conduction through such a crust resting directly on asthenosphere would give the observed heat flow if there were no extension or sedimentation. However, both processes must have been active, as the Imperial Valley is part of the Salton Trough, a pull-apart sedimentary basin that evolved over the past 4 or 5 m.y. To investigate the interrelations of these factors, we consider a one-dimensional model of basin formation in which the lower crustal gabbro and upper crustal sediments accumulated simultaneously as the crust extended and sedimentation kept pace with isostatic subsidence. For parameters appropriate for the Salton Trough, increasing the extension rate has little effect on surface heat flow because it increases effects of heating by intrusion and cooling by sedimentation in a compensating manner; it does, however, result in progressively increasing lower crustal temperatures. Analytical results suggest that the average extensional strain rate during formation of the trough was ∼20–50%/m.y. (∼1014 s−1); slower rates are inadequate to account for the present composition of the crust, and faster rates would probably cause massive crustal melting. To achieve the differential velocities of the Pacific plate at one end of the trough and North American plate at the other with this strain rate, extension must have, on the average, been distributed (or shifted about) over a spreading region ∼150 km wide. This is about 10 times wider than the present zone of active seismicity, suggesting that the seismic pattern is ephemeral on the time scale for the trough's formation. Narrow spreading zones are typical where sustained spreading is compensated by basaltic intrusion to form the thin oceanic crust, but where such spreading occurs in thicker continental crust, broader zones of distributed extension (with smaller strain rates) may be required for heat balance. The Salton Trough model suggests that distributed extension can be associated with substantial magmatic additions to the crust; their effect on crustal buoyancy has important implications for the relation between crustal extension and subsidence.
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  • 38
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    The distribution of bomb radiocarbon in the ocean (1985)
    AGU
    In:  Journal of Geophysical Research: Oceans, 90 (C4). pp. 6953-6970.
    Details
    Publication Date: 2020-07-23
    Description: Water column inventories are calculated for bomb radiocarbon at all the stations occupied during the GEOSECS and NORPAX expeditions and for the available TTO stations. The pattern of global inventories obtained in this way suggests that a sizable portion of the bomb radiocarbon that entered the Antarctic, the northern Pacific, and the tropical ocean has been transported to the adjacent temperate zones. A strategy for utilizing these inventory anomalies as constraints on global ocean circulation models is presented. Essential to this strategy are the improvement of our knowledge of the pattern of wind speed over the ocean, the establishment of the wind speed dependence of the rate of gas exchange between the atmosphere and sea, and the continued mapping of the distribution of bomb-produced radiocarbon in the sea.
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  • 39
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    Ventilation of the deep northeastern Atlantic (1985)
    AGU
    In:  Journal of Geophysical Research: Oceans, 90 (C4). pp. 6940-6944.
    Details
    Publication Date: 2020-07-23
    Description: Comparison of the 1973 GEOSECS expedition results from the deep eastern basin of the North Atlantic with those for 1981 TTO expedition reveal no firm evidence for change in NO3, PO4, or a H4SiO4. concentration. While a 2–3 μmol/kg difference is seen for O2, it is more likely experimental than temporal in origin. The combined TTO-GEOSECS data sets reveal no evidence for ventilation of the bottom waters of the eastern basin by waters from the north.
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