- Geobiology of modern and ancient cold seep ecosystems
- Trace and rare earth element geochemistry of authigenic minerals
- Trace and rare earth element geochemistry of organic matter
- Low temperature geochemical modeling of biogeochemical processes
Trace elements and sulfur isotopes in pyrite - A proxy for modes of sulfate reduction and fluid composition at methane- and oil-dominated cold seeps
The key biogeochemical process at cold seeps today is the sulfate-driven anaerobic oxidation of methane (AOM), which triggers the formation of authigenic minerals within shallow sediments. These minerals are are excellent archives of biological and geochemical processes operating through geologic time. Aside from authigenic carbonates, pyrite is the other common solid phase product of AOM at seeps, and represents an understudied archive of geochemical and microbiological processes.
Trace elemental composition in pyrite is further compared to trace elements in organic matter, oil, and host sediments, in order to assess pathways of trace element liberation and capture during early diagenesis.
This project aims to put pyrite in the spotlight as a prime target for elucidating previously unconstrained parameters that govern environmental conditions in these chemosynthesis-based settings.
Daniel Smrzka, Gerhard Bohrmann, Florence Schubotz, Wolfgang Bach, Patrick Monien (FB 5/MARUM), Harald Strauss (University of Münster), Christoph Walkner (University of Leoben), Jörn Peckmann, Zhiyong Lin (University of Hamburg)
Microbial carbonate mineralization rates: new constraints derived from authigenic methane seep carbonates
Microbial mats are the oldest ecosystems on Earth and are ubiquitous in modern terrestrial and marine aquatic environments, and are highly efficient catalyzers of mineral precipitation. Environments of abundant microbial carbonate production include marine methane seeps, where sulfate-driven anaerobic oxidation of methane is mediated by a consortium of methane-oxidizing archaea and sulfate-reducing bacteria. This microbial process induces the formation of authigenic carbonates with a high preservation potential of pristine microbial signatures.
Phase-specifc Uranium/Thorium dating and lipid biomarker content of two distinct carbonate phases identified in a 5-meter-long carbonate core sampled offshore southwestern Taiwan provide new insights into the potential influence of microbial mats on carbonate formation rates at seeps.
Daniel Smrzka, Gerhard Bohrmann, Yiting Tseng, Thomas Pape (FB 5), Jennifer Zwicker (University of Vienna), Norbert Frank, Andrea Schröder-Ritzrau (University of Heidelberg), Daniel Birgel, Jörn Peckmann (University of Hamburg), Saulwood Lin (National Taiwan University)
Carbonate precipitation at the Jøtul hydrothermal vent field
R/V MARIA S. MERIAN cruise MSM109 surveyed the Greenland Sea for hydrothermal vents previously unknown from these ultra-slow spreading ridges. A new vent field was discovered along the 500-km-long Knipovich Ridge, where hydrothermal fluids are emitting from the seafloor.
Associated with these hydrothermal fluids are precipitates containing carbonate minerals, including aragonite, calcite, and dolomite. These phases occur in various morphologies and textures within the samples. Using a comprehensive approach of petrography, mineralogy, and stable isotope and trace element geochemistry these carbonates are used as an archive to assess the evolution of emitting parent fluids at this newly discovered vent field.
Daniel Smrzka, Gerhard Bohrmann, Wolfgang Bach, Aaron Röhler (FB 5)
Putative fossilized sulfur oxidizing bacteria from Devonian cold seeps, Morocco
The colorless sulfide-oxidizing bacteria are important agents in themarine sulfur cycle, and may have been so since the Precambrian. The genera Thiomargerita, Thioploca, and Beggiatoa are all members of the colorless sulfur-oxidizing bacteria, and are among the largest unicellular organisms known on Earth.
Today, these bacteria inhabit shallow seafloor sediments where their metabolism couples the carbon, sulfur and nitrogen cycles. At modern cold methane seeps, where hydrocarbon compounds are emitted from deeper organic-rich sediments to bottom waters, sulfur oxidizing bacteria form large microbial mats that utilize dissolved reduced sulfide and oxidize it to elemental sulfur and sulfate using molecular oxygen derived from seawater. This process has a profound impact on the distribution of dissolved chemical species, microbial ecology, and the stability of authigenic carbonate minerals.
This project investigates putative Devonian microfossils of sulfur oxidizing bacteria from an ancient cold seep site from Morocco.
Daniel Smrzka (FB 5), Jennifer Zwicker (University of Vienna), Jörn Peckmann (University of Hamburg)
Phosphatic stromatolites within black shales from the Devonian - Carboniferous boundary. Rheinisches Schiefergebirge, Germany
Phosphatic stromatolites are unusual microbial fossils in the rock record. These fossil microbiota are known from the Proterozoic to the Phanerozoic, and occur in multitudes of morphologies such as oncoid, cone-like stromatolites, domal stromatolites, and microstromatolites.
A yet unknown occurrence of these unique fossils is currently under investigation from the Lower Alum Black Shale deposited during the Devonian – Carboniferous transition in Central Germany.
These microbial fossils possibly mediated one of several types of metabolisms that coupled the geomicrobiological cycles of sulfur, iron, and phosphorus.
It is the goal of this project to establish the mechanisms of phosphorite formation, as well as to elucidate possible microbial metabolisms that were active.
Jennifer Zwicker (University of Vienna), Daniel Smrzka (FB 5), Jörn Peckmann (University of Hamburg)