Carbonate authigenesis at oil seeps from the Campeche Knolls, southern Gulf of Mexico
- Autor(en)
- Daniel Smrzka, Jennifer Zwicker, Heiko Sahling, David Misch, Gerhard Bohrmann, Jörn Peckmann
- Abstrakt
The seepage of hydrocarbons from marine sediments produced by persistent upward migration of oil and gas towards the seafloor represents a poorly confined source of fossil organic carbon in the ocean and the atmosphere. Most seeps along continental margins are dominated by the expulsion of biogenic and thermogenic methane. However, an increasing number of hydrocarbon provinces have been discovered that are characterized not only by seepage of methane, but higher hydrocarbons and crude oil. Such seeps are ideally suited to study the impact of oil seepage on the diversity, activity, and distribution of microbial communities, as well as the role of oil degradation in carbonate authigenesis. The Gulf of Mexico (GoM) has served as a natural laboratory for methane and oil seepage over the last decades. In the southern GoM, the Bay of Campeche hosts the “Chapopote Asphalt Volcano”, characterized by extensive eruptions of liquid heavy hydrocarbons, widespread asphalt flows, and seafloor gas hydrate deposits. The most recent visit to this remarkable seafloor site was conducted in 2015 during R/V Meteor Cruise 114, and revealed that oil seepage is more common and widespread in the southern GoM than previously recognized. This study uses thin section petrography and stable isotope geochemistry to characterize newly discovered authigenic carbonate deposits from the southern GoM. Phase-specific trace and rare earth element analyses of aragonite cements confirm that element patterns can be used to constrain the microenvironments in which the carbonate cements had formed; these elemental patterns can also be used to constrain the influence of oil degradation on mineral authigenesis. Additionally, the software code PHREEQC is used to estimate the influence of sulfate-driven hydrocarbon oxidation on carbonate formation. As of today, the relative contribution of the oxidation of various light and heavy molecular weight hydrocarbons to carbonate authigenesis at seeps is not well known. Specifically, the effect of sulfate reduction on alkalinity, pH, and the stability and saturation state of aragonite and calcite is assessed.
- Organisation(en)
- Institut für Geologie
- Externe Organisation(en)
- Montanuniversität Leoben, Universität Bremen, Jacobs Universität Bremen, Universität Hamburg
- Publikationsdatum
- 09-2017
- ÖFOS 2012
- 105121 Sedimentologie, 105105 Geochemie
- Schlagwörter
- Sustainable Development Goals
- SDG 14 – Leben unter Wasser
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/15e344c2-caad-40c7-add0-aab423d68e75