--> Use of Sequence Stratigraphy as a Key Element in the Design of from Exploration Strategy for Microbial Buildups, Mancini, Ernest A., #90100 (2009)
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Use of Sequence Stratigraphy as a Key Element in the Design of from Exploration Strategy for Microbial Buildups

Mancini, Ernest A.1

1Department of Geological Sciences, University of Alabama, Tuscaloosa, AL.

In the Gulf of Mexico and Western Europe, Upper Jurassic microbial buildups developed in inner to outer carbonate ramp settings. These buildups attained a thickness of 58 m and were present in an area of as much as 13 km2. Microbiolites developed on a cemented and encrusted substrate or on a crystalline rock surface during a rise in Previous HitseaNext Hit Previous HitlevelNext Hit under initial zero to low background sedimentation rates in low-energy paleoenvironments characterized by fluctuating conditions. Sequence stratigraphic studies of Upper Jurassic strata serve to facilitate the design of an exploration strategy to predict the stratigraphic occurrence of these microbial buildups. The buildups developed in deposits of the transgressive to lower regressive Previous HitsystemsNext Hit Previous HittractsNext Hit. In the Gulf of Mexico, the microbes nucleated on crystalline rock associated with a basement paleohigh. Colonization corresponds to the transgressive surface that develops in association with marine flooding. The buildup continues to grow in response to Previous HitseaNext Hit Previous HitlevelNext Hit rise. A reduction in growth of the microbiolites post dates the surface of maximum transgression, which separates the transgressive and regressive Previous HitsystemsNext Hit Previous HittractsNext Hit. With this decrease in the rate of Previous HitseaNext Hit Previous HitlevelNext Hit rise, loss of accommodation, and the initiation of higher energy conditions, the microbes cease propagation. In Western Europe and parts of the Gulf of Mexico, buildups developed in the absence of basement paleohighs. Microbes nucleated on an encrusted and/or cemented surface that corresponds to the surface of maximum sediment starvation. The buildup continues to grow with continued rise in Previous HitseaNext Hit Previous HitlevelNext Hit. In these carbonate Previous HitsystemsNext Hit, the surface of maximum transgression occurs stratigraphically higher than the surface of maximum sediment starvation. Thus, the buildups occur in deposits of the transgressive and lower regressive Previous HitsystemsNext Hit Previous HittractsNext Hit. With a continued reduction in the rate of Previous HitseaNext Hit Previous HitlevelNext Hit rise and either the initiation of higher energy conditions or a high increase in background sedimentation rates, microbial growth ceases. Therefore, the initiation of microbial growth corresponds to a transgressive surface associated with crystalline rock or surface of maximum sediment starvation, and the demise of the buildup post dates the surface of maximum transgression. These Upper Jurassic buildups occur in deposits of transgressive to lower regressive Previous HitsystemsNext Hit Previous HittractsTop in the Gulf of Mexico and Western Europe.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil