Geophysical study of the northwest African margin off Morocco

Luyendyk, Bruce P.; Bunce, Elizabeth T.

doi:10.1016/0011-7471(73)90077-6

Cited by 22 publications

(12 citation statements)

References 32 publications

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“…This is also approximately the location of the boundary implied by hypotheses explaining the anomaly as an "edge effect" (Keen and Keen, 1974). Other authors have explained the East Coast anomaly itself as an oceanic spreading-type lineation, and as a consequence have placed the ocean-continent crustal interface landward of the anomaly (Emery et al, 1970;Luyendyk and Bunce, 1973;Mayhew, 1974;Sheridan, 1974). Although the exact continental-oceanic crustal boundary remains a matter of discussion (Mayhew, 1974;Rabinowitz, 1974;Keen and Keen, 1974;Sheri¬ dan, 1974), it is worth noting that a recently published multichannel reflection profile (Grow and Markl, 1977) shows oceanic basement extending landward al¬ most to the landward edge of the inner smooth zone, in contradiction to the views of Rabinowitz (1974).…”

Section: Is Probably An Upper Limit Dotted Line Would Not Violate supporting

confidence: 59%

Magnetic Anomalies and Seafloor Spreading in the Western North Atlantic, and a Revised Calibration of the Keathly (M) Geomagnetic Reversal Chronology

Vogt¹,

Einwich²

1979

Initial Reports of the Deep Sea Drilling Project

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Section: Is Probably An Upper Limit Dotted Line Would Not Violate supporting

confidence: 59%

Magnetic Anomalies and Seafloor Spreading in the Western North Atlantic, and a Revised Calibration of the Keathly (M) Geomagnetic Reversal Chronology

Vogt¹,

Einwich²

1979

Initial Reports of the Deep Sea Drilling Project

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“…2 The geology of the continental margin of Morocco has been treated by many authors (Robb, 1971;Summerhayes et al, 1971;Luyendyk and Bunce, 1973;Uchupi and Emery, 1974;Hayes and Rabinowitz, 1975;Renz et al, 1975;Hinz, 1974, 1976; Watkins and Hoppe, 1979;Wissmann and von Rad, 1979;Vail et al, 1980;Lancelot and Winterer, 1980;Roeser, 1982;Weigel et al, 1982;Jansa and Wiedmann, 1982;Hinz, Dostmann, et al, 1982;Hinz, Winterer, et al, 1982).…”

Section: Regional Physiography and Geologic Settingmentioning

confidence: 99%

The Evolution of the Mazagan Continental Margin: A Synthesis of Geophysical and Geological Data with Results of Drilling during Deep Sea Drilling Project Leg 79

Winterer¹,

Hinz²

1984

Initial Reports of the Deep Sea Drilling Project

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Combining the results of drilling during Leg 79 with other on-and offshore regional geological and geophysical data, we infer the following history for the evolution of the Mazagan sector of the Northwest African margin:1. Rifting began in the Triassic, by crustal thinning associated with listric faulting, creating a series of basins and intervening highs. The basins received continental clastic sediments from erosion of the granitic highs. By the close of Triassic time, halite with minor potash was being deposited in shallow marine salt pans across a rift-valley system, perhaps a little below global sea level, stretching from the base of the Mazagan margin (Site 546), to the base of the Nova Scotia margin, some 150-200 km northwestward.2. Marine waters quickly drowned the basin to a depth of few hundred meters during the Early Jurassic, by some combination of subsidence (perhaps w ith faulting) or basin flooding, and the shoreline advanced eastward, probably to a position not far west of Site 545. During the later part of the Early Jurassic and during Middle Jurassic time, shallowwater carbonate banks occupied parts of the fault block near Site 544 and supplied debris downslope to the area of Site 547, where hemipelagic radiolarian marls were being deposited in a slowly subsiding basin a few hundred meters deep, intermittently poorly ventilated.3. At about the end of the Bathonian, as the earliest seafloor spreading began in the central Atlantic, faulting and slightly accelerated subsidence-perhaps accompanying renewed crustal stretching-recommenced, this time especially affecting the more proximal parts of the margin near Site 545, creating the main structural relief of the Mazagan Escarpment. This faulting probably reached its maximum in Late Jurassic time, and was accompanied or immediately followed by a great transgression-the Atlantic transgression. Oxfordian carbonate reefs established themselves along the edge of the Mazagan Plateau and contributed reef talus to the slopes below. An isolated reef perched atop the fault block at Site 544 and shallow-water debris tumbled down the slopes to Site 547.4. Subsidence continued during Early Cretaceous times, but no sediments of this age were deposited (permanently) on the Mazagan Slope, perhaps because most terrigenous supplies were blocked by a submarine swell over an old granitic fault block about 15 km southeast of the Plateau edge. Huge quantities of terrigenous sand were delivered to the offshore Moroccan Basin by turbidity currents flowing down the continental slopes south of Mazagan.5. In Aptian time hemipelagic sediments (clayey nannofossil ooze) began depositing rapidly on the Mazagan Slope and accumulation continued through the Albian and most of the Cenomanian. The Slope sediments often slumped or were transported farther downslope in debris flows. Site 544, now a deep bank, stood clear of sediments.6. After a period of erosion and/or nondeposition in Turonian-Santonian time, debris flows were active again on the Slope during Campanian and Mae...

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“…After correlation of the Keathley sequence of magnetic 'L-DGO Contribution No. 2506. anomalies with the Mesozoic sequence (Larson and Pitman, 1972) the / anomaly has been correlated either with anomalies M-2 to M-4 (Luyendyk and Bunce, 1973;Laughton and Whitmarsh, 1974;Hayes and Rabinowitz, 1975) or with anomaly M-17 (Barrett and Keen, 1976;Uchupi et al, 1976). The reason it is difficult to identify the exact portion of the Mesozoic sequence to which the J anomaly corresponds is that its shape cannot be accounted for by the standard planelayer model of magnetic anomalies (i.e., uniform mag¬ netization and constant depth and thickness of the source layer).…”

Section: Introductionmentioning

confidence: 99%

The J-Anomaly in the Central North Atlantic Ocean

Rabinowitz¹,

Cande²,

Hayes³

1979

Initial Reports of the Deep Sea Drilling Project

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The J anomaly is a linear zone of high-amplitude magnetic anomalies, observed in the eastern North Atlantic north of the Canary Island lineament and the western North Atlantic north of the New England seamounts. Analyses of these anomalies show that the anomalous amplitude zones were formed at the MidAtlantic Ridge axis and thus define isochrons. Along strike, the J anomaly can be separated into two regions, one of high and one of intermediate anomaly amplitudes. In the eastern Atlantic where these amplitude variations are best documented, the boundary between the two regions occurs at a change in strike in the magnetic lineation pattern. The anomalous distribution of magnet¬ ization which is responsible for the unusual shape of the J anomaly includes crust slightly younger than MA to slightly younger than M-0. The / anomaly was probably caused by a large increase in the intensity of magnetization. DSDP Site 384 is between anomalies M-2 and M-3, and thus does not lie within the inferred zone of anomalous magnetization.

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Geophysical study of the northwest African margin off Morocco

Cited by 22 publications

References 32 publications

Magnetic Anomalies and Seafloor Spreading in the Western North Atlantic, and a Revised Calibration of the Keathly (M) Geomagnetic Reversal Chronology

Magnetic Anomalies and Seafloor Spreading in the Western North Atlantic, and a Revised Calibration of the Keathly (M) Geomagnetic Reversal Chronology

The Evolution of the Mazagan Continental Margin: A Synthesis of Geophysical and Geological Data with Results of Drilling during Deep Sea Drilling Project Leg 79

The J-Anomaly in the Central North Atlantic Ocean

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