Event Title

Biology and Geology of Hydrocarbon Seeps: Modern and Cretaceous

Presenter Information

Erica Morelli, Oberlin College

Location

Science Center, Bent Corridor

Start Date

9-26-2014 12:00 PM

End Date

9-26-2014 1:20 PM

Poster Number

30

Abstract

Hydrocarbons stored deep below the Gulf of Mexico are a major target of petroleum exploration. Interestingly, the liquid petroleum and natural gas will naturally flow toward the seabed along faults and seep through modern sediments. When this happens, microbes take advantage of the hydrocarbons by oxidizing them as part of their chemosymbiotic metabolism. When microbes are active at seeps, they alter the sediment geochemistry which results in formation of carbonate and barite rocks within the sediment. These microbial ecosystems linked to geologic formations creates a unique environment for the development of deep sea invertebrate communities. This summer project involved the comparison of samples of carbonate rock from deep-sea environments in the present day Gulf of Mexico (GOM) with samples from the Tepee Butte rock formations of Colorado and confirms that the Cretaceous rock examples must have also formed through some association with hydrocarbon seepage on the seafloor. Through petrographic analysis and Scanning Electron Microscope methods of data collection, samples from OCSG and Green Canyon seep sites in the Gulf of Mexico were revealed to be made up primarily of carbonate rock with a particular set of macrofaunal assemblages. Samples from an additional site in the Gulf of Mexico, Garden Banks, were found to be primarily composed of barite with a generally smaller association of organisms. Further analysis of Cretaceous samples (Tepee Buttes) revealed mainly a carbonate composition with larger inclusions of barite than the modern day carbonate samples as well as similar faunal associations with both types of modern day sites. The inclusion of barite in the Tepee Buttes samples as well as trace amounts of barite found through SEM analysis of carbonate samples from the modern day GOM samples could indicate a possible succession of stages of chimney rock growth in deep-sea hydrocarbon seep environments. Particular groupings of faunal associations with seep sites could also point to possible differences in seep chemistry and/or seep flow.

Project Mentor(s)

Karla Parsons-Hubbard, Geology

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Sep 26th, 12:00 PM Sep 26th, 1:20 PM

Biology and Geology of Hydrocarbon Seeps: Modern and Cretaceous

Science Center, Bent Corridor

Hydrocarbons stored deep below the Gulf of Mexico are a major target of petroleum exploration. Interestingly, the liquid petroleum and natural gas will naturally flow toward the seabed along faults and seep through modern sediments. When this happens, microbes take advantage of the hydrocarbons by oxidizing them as part of their chemosymbiotic metabolism. When microbes are active at seeps, they alter the sediment geochemistry which results in formation of carbonate and barite rocks within the sediment. These microbial ecosystems linked to geologic formations creates a unique environment for the development of deep sea invertebrate communities. This summer project involved the comparison of samples of carbonate rock from deep-sea environments in the present day Gulf of Mexico (GOM) with samples from the Tepee Butte rock formations of Colorado and confirms that the Cretaceous rock examples must have also formed through some association with hydrocarbon seepage on the seafloor. Through petrographic analysis and Scanning Electron Microscope methods of data collection, samples from OCSG and Green Canyon seep sites in the Gulf of Mexico were revealed to be made up primarily of carbonate rock with a particular set of macrofaunal assemblages. Samples from an additional site in the Gulf of Mexico, Garden Banks, were found to be primarily composed of barite with a generally smaller association of organisms. Further analysis of Cretaceous samples (Tepee Buttes) revealed mainly a carbonate composition with larger inclusions of barite than the modern day carbonate samples as well as similar faunal associations with both types of modern day sites. The inclusion of barite in the Tepee Buttes samples as well as trace amounts of barite found through SEM analysis of carbonate samples from the modern day GOM samples could indicate a possible succession of stages of chimney rock growth in deep-sea hydrocarbon seep environments. Particular groupings of faunal associations with seep sites could also point to possible differences in seep chemistry and/or seep flow.