climate and Earth processes
biogeochemistry Simon Brassell, Erika Elswick, Lisa Pratt, Ed Ripley, Peter Sauer, Juergen Schieber, Arndt Schimmelmann,
Laura Wasylenki, Chen Zhu
SIMON BRASSELL Professor of Geological Sciences
Simon’s research activities continue to be fo-
cused on the use of the molecular and isotopic
compositions of sediments to elucidate paleo-
climates and paleoenvironments, and to study
the fate of organic matter in the geosphere.

Recent investigations by Devon Colcord as part
of her M.S. and Ph.D. studies have included as-
sessment of climate records in lake sediments
from Greenland, studying cores collected by
the GetGamm program led by Lisa Pratt. Two
publications in Organic Geochemistry have
verified that the distributions of molecules
biosynthesized by bacteria known as branched GDGTs (glyc-
erol dialkyl glycerol tetraethers) include contributions from
autochthonous sources within lakes augmenting their origin
from surrounding soils, and confirmed this conclusion by the
first direct measurement of the carbon isotope composition
of these molecules in collaboration with Professor Ann Pear-
son at Harvard University. Another recent publication in Or-
ganic Geochemistry reports the results from the M.S. thesis
of Amishi Kumar, who elucidated the separate contributions
of polycyclic aromatic hydrocarbons originating from both
natural and anthropogenic sources of both petrogenic and py-
rolytic compounds within sediments from the Santa Barbara
Basin, offshore California.

Over the past couple of years, investigations led by
Ph.D. students Devon Colcord and Andi Shilling are elu-
cidating changes in climate recorded by biogeochem-
ical indices in a series of early Pleistocene lacustrine
sediment cores recovered from Olduvai Gorge. This
research is part of a larger collaborative project led by
Jackson Njau, Nick Toth, and Kathy Schick that aims
to explore environmental change during critical inter-
vals of hominin evolution established at Olduvai. The
laminated sediment sequence from ~1.8 Ma provides
an extraordinary opportunity to determine short-term
changes in climate that triggered responses in the lake
phytoplankton and surrounding vegetation at a time of
high hominin diversity.

Simon continues to work on profiling ancient climates
and is a co-author of a recent paper focused on a com-
prehensive collation of temperature records for the
Cretaceous, which has been published in Earth Science
Reviews. He is also collaborating with Arndt Schim-
melmann and Maria Mastalerz in analysis to better un-
derstanding the specific nature of catalytic processes
transforming organic matter during diagenesis in the
New Albany and other shales.

Simon teaches both a fully online introductory ocean-
ography course that utilizes web-based resources in
student exercises exploring a wide range of oceano-
graphic phenomena and a College critical approaches
class on records of global climate change.

ERIKA ELSWICK Senior Lecturer and Director, Analytical Chemistry Laboratory
News From the Analytical Geochemistry Laboratory
Erika R. Elswick - Director
Fall 2017 has brought a lot of additional activity to the Analytical Geochemistry Laboratory with a full class
in Methods in Analytical Geochemistry (G444/G544). In the spring we acquired a new ion chromatograph
for the analysis of anions in water samples. The new Thermo/Dionex instrument replaces a much older
unit, and is very student friendly. We continue to analyze aqueous solutions and solids for departmental
members, as well as colleagues in other departments and units across campus.

During the summer of 2017 I embarked on a new project with a colleague to begin to instrument a wetland
located in the National Forest land above the IU Field Station associated with the late 19th and early 20th
Century mining activities. We ultimately hope to shed some light on this dynamic setting to develop mod-
els for remediation at higher altitudes. ​
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