Passive margins: A model of formation

Pichon, Xavier Le; Sibuet, Jean‐Claude

doi:10.1029/jb086ib05p03708

Cited by 410 publications

(165 citation statements)

References 25 publications

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“…Extension of the lithosphere results in decompression of the underlying asthenosphere, causing partial melting and advection of hot asthenospheric material to the base of the lithosphere and into the space created by its extension (LePichon and Sibuet, 1981;Spohn and Schubert, 1983;Neugebauer, 1983;McKenzie and Bickle, 1988;Ziegler, 1992). Continued lithosphere thinning causes further decompression of the asthenosphere and the generation of additional partial melts.…”

Section: Eclogite Lens Formation In the Upper Mantle Beneath Extendedmentioning

confidence: 99%

Extensional basins of the former Soviet Union — structure, basin formation mechanisms and subsidence history

et al. 1996

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We review the structure and evolution of a number of Riphean-Phanerozoic rifts and extensional basins within the territory of the former Soviet Union (FSU). Horst-and-graben formation in strong crustal and subcrustal lithosphere layers can explain the multi-trough character of rift systems observed in the Russian platform, the Vilyuy rift, the West Siberian rift system, the Pechora-Kolva rift system and the Laptev Sea rift. Many features in the evolution of these rifted basins are incompatible with predictions of classical stretching models. Basin subsidence often occurs in the absence of any noticeable stretching and over time scales much longer than predicted by models of thermal subsidence. Other observations include a time gap between rifting and the onset of post-rift basin subsidence of tens to hundreds Ma and a correlation in timing of subsidence phases of rifted basins and platforms with opening and closure events of adjacent ocean basins. These observations point to an important role for mechanisms such as eclogite formation within or beneath the lithosphere as well as intraplate compression and stress-induced lithospheric deflection.

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Section: Eclogite Lens Formation In the Upper Mantle Beneath Extendedmentioning

confidence: 99%

Extensional basins of the former Soviet Union — structure, basin formation mechanisms and subsidence history

et al. 1996

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“…These faults dip toward the axis of the N 350° depression and produced tilted fault blocks. The consequence of this type of tectonics is an increase in the initial dip of the basement reflectors in province 2, whereas the dip angle of reflectors in province 1 is reduced because of the rotation of the tilted fault blocks (e.g., LePichon and Sibuet, 1981).…”

Section: Structural Evolution Of Walvis Ridge and Adjacent Basinsmentioning

confidence: 99%

“…The oceanic crust on Walvis Ridge was emplaced close to sea level, as in the Afar region. This requires less thinning of the continental crust than took place on the adjacent continental margins (LePichon and Sibuet, 1981). At least part of the oceanic crust of province 3 may have been emplaced before any oceanic crust formed in the adjacent basins.…”

Section: Structural Evolution Of Walvis Ridge and Adjacent Basinsmentioning

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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“…The domino model method was used (Le Pichon & Sibuet 1981;Jackson & McKenzie 1983). This model assumes basement blocks rotate during crustal extension and slide past each other along bounding normal faults.…”

Section: Half-graben Geometry and Extensionmentioning

confidence: 99%

Extensional tectonism and magmatism during the middle Cretaceous to Paleocene, North Westland, New Zealand

Bishop

1992

New Zealand Journal of Geology and Geophysics

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Open-file seismic reflection data, from the offshore area west of Greymouth, show a large segmented half-graben structure, over 40 km long, up to 15 km wide, and trending WNW-ESE. Although the structure is not drilled, regional seismic interpretation suggests it is of Cretaceous age. The geometry of the structure indicates extension of about 20%. Strata of similar age onshore are thought to have been deposited in half-grabens with a similar orientation. In contrast, structures containing Late Cretaceous to Paleocene deposits onshore, trend NNE-SSW, almost at right angles to the earlier trend. Cretaceous dike orientation data show a bimodal distribution, with the main trends being WNW-ESE and NNE-SSW. Together with published radiometric and fission-track ages from basement and Cretaceous igneous rocks, these data show that there were at least three distinct periods of tectonic/magmatic activity: (1) NNE-SSW directed extension, uplift, plutonism, and minor volcanism in the interval 125-90 Ma; (2) multiple dike intrusion and decreased NNE-SSW directed extension and uplift in the interval 90-80 Ma; and (3) breakup unconformity, volcanism, dike intrusion, waning subsidence in WNW-ESE trending basins, initiation of NNE-SSW transtensional basins, and uplift in the interval 80-60 Ma.

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Passive margins: A model of formation

Cited by 410 publications

References 25 publications

Extensional basins of the former Soviet Union — structure, basin formation mechanisms and subsidence history

Extensional basins of the former Soviet Union — structure, basin formation mechanisms and subsidence history

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

Extensional tectonism and magmatism during the middle Cretaceous to Paleocene, North Westland, New Zealand

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