Sedimentation and Accumulation of organic carbon in the Angola Basin and on Walvis Ridge: Preliminary results of Deep Sea Drilling Project Leg 75

Hay, William W.; Sibuet, Jean‐Claude; Barron, Eric J.; Boyce, R.E.; Brassell, Simon C.; Dean, Walter E.; Huc, A.; Keating, Barbara H.; McNulty, C. L.; Meyers, Philip A; Nohara, Masato; Schallreuter, Roger; Steinmetz, John C.; Stow, Dorrik; Stradner, Herbert

doi:10.1130/0016-7606(1982)93<1038:saaooc>2.0.co;2

Cited by 29 publications

(40 citation statements)

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“…As continental elastics disappeared, carbonates eroded from the Walvis Ridge/continental margin resulted in the progradation of a detrital carbonate fan during the Campanian and Maestrichtian. Beginning in the Paleocene, sedimenta- (Hay, et al, 1982) and southeastern Angola Basin seismic units (this investigation), each shown with their measured interval velocities. A hachured area indicates no velocity data for that interval.…”

Section: Discussionmentioning

confidence: 99%

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Multichannel Seismic Reflection Survey of the Southeastern Angola Basin

Musgrove¹,

Austin²

1984

Initial Reports of the Deep Sea Drilling Project

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Section: Discussionmentioning

confidence: 99%

“…25). Two main types of deposits are recognized: open-ocean pelagic and hemipelagic sediments, and sediments deposited downslope by turbidity currents and debris flows (Hay et al, 1982). (Hay, et al, 1982).…”

Section: Sedimentsmentioning

confidence: 99%

Multichannel Seismic Reflection Survey of the Southeastern Angola Basin

Musgrove¹,

Austin²

1984

Initial Reports of the Deep Sea Drilling Project

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“…This synthesis chapter relates results of Leg 75 drilling in the Angola Basin (Site 530) and on the Walvis Ridge (Sites 531 and 532) (Hay, Sibuet et al, 1982) to the framework of the early evolution of the South Atlantic Ocean and formation and evolution of the Walvis Ridge.…”

Section: Introductionmentioning

confidence: 99%

Early Evolution of the South Atlantic Ocean: Role of the Rifting Episode

Sibuet¹,

Hay²,

Prunier³

et al. 1984

Initial Reports of the Deep Sea Drilling Project

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For the South Atlantic Ocean, the rifting period began during the Oxfordian-Kimmeridgian and ended progressively from the Hauterivian near the Agulhas Plateau to the early Albian in the vicinity of the Niger Delta. The Walvis Ridge/Rio Grande Rise system acted as a dam to marine incursions into the Angolan and Brazilian basins until the midAptian. The Parana Basin and the Torres syncline (Brazil), the Eastern Walvis Ridge and the Kaokoveld region (Namibia) form an originally continuous volcanic terrane created in the continental domain during the Late Jurassic-Early Cretaceous by tensional processes. This terrane corresponds to a failed rift arm extending into South America and involving about 100 km of extension in the Late Jurassic to Early Cretaceous. These factors provide new constraints for the early kinematic evolution of the South Atlantic.

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“…7). Expansion of aridity to the whole basin may have been a result of the location of the basin within the broad continental expanse of rifting Gondwanaland, and of effects of the topography of the uplifted margins of the young ocean basin Hay et al, 1982).…”

Section: Middle Cretaceous Black Shalesmentioning

confidence: 99%

Geologic Evolution, Sedimentation, and Paleoenvironments of the Angola Basin and Adjacent Walvis Ridge: Synthesis of Results of Deep Sea Drilling Project Leg 75

Dean¹,

Hay²,

Sibuet³

1984

Initial Reports of the Deep Sea Drilling Project

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The section recovered at Site 530 (Holes 53OA and 530B) consists of eight sedimentary units and one basalt unit. The composition of the basalt recovered in Hole 53OA is distinct from typical mid-ocean ridge basalts (MORBs) but is similar to that of Hawaiian tholeiites and basalt from the central part of Walvis Ridge. Throughout most of its history, the southern Angola Basin received large volumes of redeposited material in the form of turbidites and, most recently, debris-flow deposits. Most of this material was derived from Walvis Ridge to the south, but thickness trends of acoustic units suggest that some of the sediment was derived from the African continental margin to the east.The basal sedimentary unit (Albian to Santonian) at Site 530 contains 262 beds of black shale that are interbedded with green and red claystone. Black shale makes up less than 10% of the total section, but in two cores of early Turonian age, black shale beds compose about 50% of the section. The black shales contain up to 19% organic carbon (average of about 5%) that is mainly of autochthonous marine origin but with significant contributions from terrigenous organic matter. The origin of these more-and less-reduced interbedded lithologies with varying amounts and types of organic matter, and variable amounts of pelagic, hemipelagic, and turbiditic sediment is complex and cannot be explained by any one simple process. Many factors affecting the concentration of dissolved oxygen in the bottom waters of the Angola Basin varied throughout the middle Cretaceous to produce bottom-water conditions that fluctuated between mildly oxic and oxygen-deficient, but most of the time bottom-waters and sediment-interstitial waters were sufficiently oxic to permit the accumulation of red oxidized sediment.A relatively complete sedimentary record of the Cretaceous/Tertiary boundary was recovered within a sequence of mudstone and marlstone turbidites in Hole 530A. There is a significant increase in the concentration of iridium above background levels at the boundary. High concentrations of many other elements also occur within the same stratigraphic interval as the iridium anomaly. Furthermore, there is a marked decrease in CaCO 3 in the Tertiary strata above the iridium anomaly which suggests that the production of shallow-water carbonate also may have been affected by whatever caused elevated concentrations of iridium and other elements. These observations are consistent with the asteroid-impact theory proposed to explain the worldwide occurrence of an iridium anomaly at the Cretaceous/Tertiary boundary.The Cenozoic history of the Angola Basin was controlled mainly by (1) restriction of bottom-water flow from the south by Walvis Ridge; (2) development of glaciation on Antarctica; (3) opening of circulation passages in the southern oceans; (4) rapid turnover of cold, nutrient-rich waters that resulted in high productivity of diatoms; (5) influx of terrigenous sediment mainly by turbidity currents; and (6) production and preservation of carbonate...

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Sedimentation and Accumulation of organic carbon in the Angola Basin and on Walvis Ridge: Preliminary results of Deep Sea Drilling Project Leg 75

Cited by 29 publications

References 0 publications

Multichannel Seismic Reflection Survey of the Southeastern Angola Basin

Multichannel Seismic Reflection Survey of the Southeastern Angola Basin

Early Evolution of the South Atlantic Ocean: Role of the Rifting Episode

Geologic Evolution, Sedimentation, and Paleoenvironments of the Angola Basin and Adjacent Walvis Ridge: Synthesis of Results of Deep Sea Drilling Project Leg 75

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