2019 AAPG Annual Convention and Exhibition:

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Paleobathymetric Interpretation Via Analog Analysis

Abstract

Foraminifera are the best-suited microorganisms for paleoenvironmental analysis given their abundance, post-mortem preservation, statistically significant occurrence, and response to environmental changes. Foraminifera are almost exclusively marine and their distribution is controlled by parameters such as dissolved oxygen, temperature, nutrients, substrate, turbidity, salinity, etc. Most of these parameters vary with water depth, thus foraminifera distribution can successfully be used for paleobathymetric interpretation. In the Gulf of Mexico, the correlation between benthic foraminifera distribution and water masses is well established. A database of over eighty benthic foraminifera analogues covering water depths in a range from inner neritic to water depths exceeding 3000 meters and spreading an area from East Breaks to East of the Mississippi River have been successfully used in paleobathymetric analysis of multiple wells in deep water Gulf of Mexico (GOM). Paleobathymetric analysis can be used as a proxy for distinguishing between shelf, slope, and basin floor environments. It is important, however, to be mindful of the fact that water depth and platform margin physiography are independent factors and must be reconciled to avoid erroneous interpretations, particularly with regards to neritic and upper bathyal environments. This analog database has been also used for distinguishing between in situ and transported benthic foraminifera in deep water GOM revealing non-segregated transported microfossil distribution in fill and spill systems (Brazos-Trinity) and segregated distributions in single intra-slope basins (Mars - Ursa) during the Pleistocene sea level fall (~70Ka - ~20Ka). The capability of linking transported microfossil to various depositional system is important in deep water GOM.