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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 9. (September)

First Page: 1659

Last Page: 1659

Title: Organic Matter Type and Hydrocarbon Occurrences on Eastern Canadian Margin: ABSTRACT

Author(s): M. S. Barss, J. P. Bujak, G. L. Williams

Article Type: Meeting abstract


The type of organic matter present in the Mesozoic-Cenozoic sections of offshore eastern Canada is related to the geologic histories of the western North Atlantic Ocean and the Labrador Sea. On the Scotian Shelf-Grand Banks, marine organic matter (amorphogen), largely the remains of phytoplankton and the primary precursor of oil, did not become abundant until the Late Jurassic, and then only where marine conditions were more fully developed. Floods of terrestrial organic material in deltaic sediments considerably diluted the amorphogen in the Early Cretaceous, particularly on the Scotian Shelf. In contrast, amorphogen continued to be common in the East Newfoundland Basin. Major marine transgression led to uniformly abundant amorphogen throughout the Late Cretaceous and Ce ozoic of the Scotian Shelf and Grand Banks, with terrestrial organic material only becoming important in the Neogene. Coloration studies indicate that sediments are generally immature in the Late Cretaceous-Cenozoic, except in: (1) areas where the Cenozoic is extremely thick in the East Newfoundland Basin and Labrador Shelf; and (2) where anomalously high geothermal gradients result as from salt intrusion. Older strata, where mature, are generally gas-prone, except where amorphogen is common. The Labrador Shelf shows a similar but later sequence of organic types with amorphogen being common only in the Paleogene. Our results are consistent with hydrocarbon distribution encountered to date in offshore eastern Canada. They also indicate that the relative abundance of amorphogen increases i an offshore direction, of particular importance where the type of organic material is the limiting factor for oil generation as in the Late Jurassic-Early Cretaceous.

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Copyright 1997 American Association of Petroleum Geologists