--> ABSTRACT: Great Aptian Lake System of the South Atlantic, by Kevin Burke; #90906(2001)

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Kevin Burke1

(1) Dept. Geosciences ,University of Houston, Houston, Tx, TX

ABSTRACT: Great Aptian Lake System of the South Atlantic

It is now about 25 years since it was first suggested( in Geology 1975) that the newly-formed ocean floor of the South Atlantic between the Walvis ridge barrier and the Niger delta was overlain by a shallow-water lake rather than by waters of oceanic depth during much or all of the interval between c.126 Ma, when ocean floor began to form, and the time of deposition of the Late Aptian evaporites (c.112 Ma). Results published in recent years have made it possible to revisit the suggestion and to ask such further questions as : How was the ocean floor, at c.3km below sea level, linked to the continental margin rift systems that also contain Aptian evaporites ? Can appreciation of the importance of the deposition of evaporites directly onto the ocean floor help in understanding of the location of the broad ocean to continent transition zone of the S. Atlantic . Did the lake system extend westward along the Guinea and Brazilian coasts, although there appear to be no Aptian evaporites in those areas ? Have organic-rich sedimentary rocks deposited in the lake (or lake-system) been involved in generating oil and gas that have subsequently charged Later Cretaceous and Cenozoic reservoir rocks along the continental margins ? Are there places where the pre-evaporite lake deposits that were laid down on top of the ocean-floor might be reached by the drill ? Might there be charged reservoir rocks among those lake deposits?

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado