Seismic stratigraphic framework of Louisiana Continental Margin: clues to hydrocarbon sourcing
Interpretation of several thousand miles of multichannel seismic data indicates that large volumes of continental rise and basinal sediments have been continuously entrapped and are overridden by the basinward flow or creep of broad, extensive salt tongues that form the lower slope and Sigsbee Escarpment. Thick accumulations of Lower Cretaceous to upper Miocene sediments are identified beneath the salt at least 60 km landward of the escarpment. Spotty seismic data suggest that the Cretaceous to middle Miocene succession extends up to 120 km landward of the escarpment and beneath the present shelf break. Pleistocene-Holocene sequences of the deep gulf can be traced up to 15 km landward of the escarpment, where they are truncated by the base of the salt. Similar truncation of older deep gulf sequences by salt occurs progressively farther landward of the escarpment. Recently, the case has been made that hydrocarbons found in seeps and reservoirs on the outer shelf and upper slope are generated from Miocene anoxic basins buried at depth. Anoxic slope basins are presently rare, and their total sediment volume is small. It is unlikely that these anoxic basins were significantly more numerous during the Miocene or that their sediment volume was significantly greater. Therefore, the scenario of large allochthonous salt tongues, or flows, overriding flat continental rise and basinal sediments high in organics suggests that: (1) much of the hydrocarbon found in shallow Pliocene-Pleistocene reservoirs along the shelf and upper slope may have been generated from the now deeply buried Cretaceous to early Tertiary marine sedimentary sequences since the late Miocene-early Pliocene, and (2) hydrocarbons migrated vertically upward relatively recently along postsedimentary faults that cut the decollement.
- Research Organization:
- ARCO Exploration and Technology Co., Plano, TX
- OSTI ID:
- 6932000
- Report Number(s):
- CONF-8610199-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 70:9; Conference: 36. annual meeting of the Gulf Coast Association Geological Societies and the Gulf Coast Section of SEPM, Baton Rouge, LA, USA, 22 Oct 1986
- Country of Publication:
- United States
- Language:
- English
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