nai

Project Progress

This year we published a paper in Geology which proposed that episodic release of hydrogen sulfide (H₂S ) from the ocean caused the end-Permian mass extinction. Moreover, we suggested that the underlying environmental driver, euxinic deep waters (enriched in H₂S), may have been the norm during a billion years of Earth history (from 1.8 Ga to 0.8 Ga), and that H₂S eruptions may have delayed colonization of the land surface.

Our work at Fayetteville Green Lake, NY continues, in collaboration with Kate Freeman (PSU), Chris House (PSU) and Michael Arthur (PSU). This is a meromictic lake with a sulfidic monimolimnion and a chemocline at ~20m water depth that supports a S-based phototrophic community dominated by purple sulfur bacteria (Figure 1), benthic carbonate buildups produced by cyanobacteria (Figure 2), and sulfidic seeps colonized by chemoautotrophic sulfur-oxidizing bacteria (Figure 3). We are studying this lake as an analog Proterozoic ocean ecosystem. Coring sediments across the chemocline has revealed a signature that may prove to be diagnostic of the intersection of a chemocline with bottom sediments. If so, we will have a tool to explore shifts in chemoclines in ancient rocks, including the shift to the air-sea interface we propose for the Permian event.

We are also collaborating with Greg Retallack (U. Oregon) and Shuhei Ono (Carnegie Institute) on a study of unusual S enrichments in Proterozoic and Late Permian paleosols. Such enrichments would be expected if H₂S did indeed erupt into the atmosphere during times when the deep sea was euxinic.

Another publication addressed the nature of hydrothermal fluid emissions during the Precambrain. This work, in collaboration with Bill Seyfried (U. MN) explored the consequences of low seawater sulfate concentrations and possibly shallower ridge depths for midocean ridge fluid compositions (Kump and Seyfried, 2005). In short, vent fluids were likely Fe and H₂-rich and S poor during the Precambrian. We discuss implications for Precambrian banded-iron deposition and vent community metabolism.

Kump also traveled to Arctic Russia to conduct field research on the Archean-Proterozoic transition, in collaboration with Victor Melezhik and others. This collaboration has already led to a manuscript submitted to GSA Today and funding for a International Continental Drilling Program workshop to develop a drilling proposal.

Kump and master’s student Ellen Herman have a paper in press in Geobiology that describes a numerical model of a microbial mat and its sensitivity to changing overlying water conditions. In particular, we investigate how the biogeochemistry of a mat responds to changes in the sulfate and oxygen concentration of the overlying water (relevant to the behavior of microbial mats during the Precambrian.

{{ 1 }}

{{ 2 }}

{{ 3 }}