2014

2014 Dec 04

Paleobiology Seminar: "Diastem Didactic: Some Recent Advances in Late Cretaceous Geochronology, Chronostratigraphy, and OAE Studies"

1:30pm to 2:30pm

Location: 

Haller Hall (Geology Museum 1020

Speaker: Dr. Brad Sageman (Northwestern University)

Abstract: In 1917, Joseph Barrell published a paper titled "Rhythms and the Measurements of Geologic Time" in which he proposed that the sedimentary record was made up of more surfaces representing missing time than rock representing recorded time.  This insight has been appreciated for generations since, and eventually led to the development of an...

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2014 Nov 13

Geobiology Seminar: "How salty was the sea? New constraints on seawater chemistry from ancient evaporites"

4:00pm to 5:00pm

Location: 

Haller Hall (Geology Museum 102)

Speaker: Dr. Clara Blattler (Princeton University)


Abstract: It is surprising that we cannot robustly answer the question: “Why is the sea salty?” The major-element composition of seawater acts as an important boundary condition that shapes how we interpret marine...

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2014 Oct 02

Geobiology Seminar: "Illuminating sulfur isotope mass-independent fractionation (S-MIF)"

4:00pm to 5:00pm

Location: 

Haller Hall (Geology Museum 102)

Speaker: Andrew Whitehill (MIT)

Abstract: Sulfur isotope mass-independent fractionation (S-MIF) is ubiquitous in Archean and Paleoproterozoic sedimentary rocks and provides the most convincing evidence for a low-oxygen early (pre-2.4 Ga) atmosphere.  The abrupt...

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2014 Sep 11

Paleobiology Seminar: "Mesozoic Tectonics, Oceanic Anoxic Events, and the Evolution of Planktic Foraminifera"

4:00pm to 5:00pm

Location: 

Haler Hall (Geology Museum 102)

Speaker: Dr. Mark Leckie (UMass-Amherst)

Abstract:

Global tectonics had a profound influence on climate, weathering, sea level, and seawater chemistry during Mesozoic time. The linkages between tectonic activity, planktic foraminiferal evolution and environmental perturbations, including the so-called Mesozoic ‘Oceanic Anoxic Events’ (OAEs) are compelling. Diversification and extinction are closely tied with the major OAEs...

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2014 Apr 18

Geobiology Seminar: "High-temperature kinetics of clumped isotopes in calcite and apatite"

5:00pm

Location: 

Haller Hall (Geology Museum 102)

Speaker: Daniel Stolper (Caltech)

Abstract:

The abundance of multiply substituted (‘clumped’) isotopologues (e.g., 13C16O218O2-) in carbonates is a thermodynamically controlled function of temperature for equilibrated systems. Measurement of clumped isotope abundances can thus be used under certain circumstances to measure carbonate formation...

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2014 Apr 17

Geobiology Seminar: "New insights into the formation of methane at both low and high temperatures using stable isotopes"

12:00pm to 1:30pm

Location: 

Haller Hall (Geology Museum 102)

Speaker: Daniel Stolper (Caltech)

Abstract:

Methane is a critical greenhouse gas, energy resource, and product of microbial metabolisms. Despite its importance in the carbon cycle, distinguishing the sources of methane in natural systems is challenging due to gas migration and potentially overlapping chemical and isotopic characteristics of biogenic and thermogenic sources. Knowledge of the formation...

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2014 Mar 13

Geobiology Seminar: "On the mechanism of sulfite reduction by the dissimilatory sulfite reductase DsrAB"

12:00pm to 1:00pm

Location: 

Haller Hall (Geology Museum 102)

Speaker: Dr. Ines Pereira (ITQB, Portugal)

Abstract:

A key reaction in microbial sulfur metabolism is the reduction of sulfite by the dissimilatory sulfite reductase, DsrAB. This enzyme is present in sulfate, thiosulfate and sulfite reducing organisms, and also in sulfur-oxidizers where it is thought to operate in reverse. The mechanism of sulfite reduction by DsrAB has long been the subject of controversy due to the in vitro formation of...

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