Isotopic, molecular and organic geochemistry, astrobiology

Biogeochemistry is a subdiscipline within the geological and environmental sciences. Research in biogeochemistry is inherently multidisciplinary, reflecting complex process at the intersection of biology, geology and chemistry .

A diverse range of research directions is represented by ten IU faculty in the Biogeochemical Laboratories in the Department of Geological Sciences. Click on names to connect to individual home pages for more detailed information on research and complete lists of publications.

Simon Brassell

Professor of Geological Sciences. Molecular and isotopic characteristics of organic matter. Biogeochemical processes. Paleoclimates. Biochemical evolution. Petroleum Carbon cycling.

Biogeochemical responses to climatic and environmental change that are preserved in the occurrence, abundance and isotopic composition of organic matter in sediments. Biological origins and geological fate of organic compounds, and the processes that influence their production, changes during burial diagenesis and thermal alteration, and potential for survival in the sedimentary record. Alkenone distributions as proxies for oceanic surface water temperatures, including assessment of spatial and seasonal influences in the contemporary ocean. Climate records in lake sediments and oceanic particulate material; seasonal and annual changes in oceanic primary productivity and in CO2 uptake by phytoplankton. Molecular and carbon isotopic records of critical intervals of geological time as evidence of past perturbations in the global carbon cycle. Cretaceous sedimentary environments, organo-sulfur and other heteroatomic consituents of sediments, and use of molecular indices to assess the origins, thermal history and migration history of source rocks and petroleums.

Chris Craft

Professor of Public and Environmental Affairs . Adjunct Professor Geological Sciences. Terrestrial and wetland ecosystem restoration, wetlands ecology, soil resources, biogeochemistry, nutrient cycling and carbon sequestration of soils and sediments

Radiogenic isotopes 210Pb and 137Cs for sediment dating; stable isotopes in ecological research. Impacts of human activities on carbon and nutrient cycling in wetland and terrestrial ecosystems; wetland biogeochemistry, including hydroperiod alteration and eutrophication, plant-soil-landscape nutrient relationships, carbon cycling, peat accretion and peatland ontogeny. Ecosystem Restoration; evaluating of ecosystem developments.

Erika Elswick

Senior Lecturer and Director, Analytical Geochemistry Laboratory. Stable isotopes in sedimentary environments and ore deposits. Metals in the environment. Tropical soils. Low temperature hydrothermal rock–water interactions. Microbial activity.

Diagenetic processes at low temperatures in sedimentary depositional environments; geochemistry of black shales; relationship of organic carbon and sulfur in host rocks of sediment-hosted massive Pb-Zn-Ba sulfide deposits, and the hydrocarbon source rock potential of these environments. Lead and other metal pollution from highway runoff in tropical soils. Sulfur stable isotopes.

Maria Mastalerz

Research Scientist/Coal Geologist, Indiana Geological Survey. Adjunct Faculty: Geological Sciences. Coal geology. Petrology and chemistry of coal, kerogen and bitumen. Coalbed methane and carbon dioxide adsorption. Stable isotopes. Properties of coal combustion products.

Coal and organic petrography (reflected light microscopy) and coal and maceral chemistry. Coal geology and sedimentology. Coalbed methane potential and its controls (research involves field core description, sample collection, canister desorption, coal characterization, and gas-in-place calculations). Anthropogenic organic matter from coal-combustion and steel and coke plant emissions in modern sediments. Role of hydrogen and nitrogen in kerogen maturation processes. Development and application of new analytical techniques to study organic matter in-situ (for example, light element quantification using the electron microprobe, or micro-Fourier-Transform-Infra-Red spectroscopy, FTIR). Associations between organic matter and metals.

Lisa Pratt

NASA Planetary Protection Officer and Provost’s Professor Emeritus of Geological Sciences. Geomicrobiology of extremophiles. Biotic and abiotic fractionation of S isotopes. Life- detection probes for deployment in Mars subsurface. Cretaceous C isotope excursions.

Stable isotopic and organic geochemical studies of sulfur are conducted on waters and sediments from modern environments ranging from basalt-hosted alkaline lakes to deep mines to Antarctic dry-valley lakes. Pratt and her students also study black shale from Precambrian and Cretaceous marine sequences. Sulfur isotopic data are used to trace complex biogeochemical pathways that link the hydrosphere, lithosphere and biosphere. Shifts in these pathways are often indicative of biotic responses to paleoclimatic and/or paleoceanographic change.

Edward M. Ripley

Professor of Geological Sciences. Genesis of metallic ore deposits. Applications of stable isotopic geochemistry in petrology. Igneous and hydrothermal processes on metals. Thermodynamic/kinetic modeling.

Ore genesis and stable isotope geochemistry. Role of organic matter in metal enrichment within black shales and both hydrothermal and magmatic ore deposits. Role of organic activity in mediating sulfur isotopic distribution in sedimentary rocks and their metamorphosed equivalents.

Peter Sauer

Assistant Scientist. Stable isotopes (C, N, H, O). Paleoclimatic records from sediments, tree-rings, and soils. Transformations of organic matter during diagenesis and maturation of oil and coal.

Use of geochemical proxies to reconstruct the paleoclimatic history of the earth; isotope geochemistry of fresh water lakes and terrestrial leaf-waxes; lacustrine sediments and climate history. Stable isotopes in fossil fuel research.

Arndt Schimmelmann

Senior Scientist. Stable isotopes in fossil fuels, Stable isotopes in biomass, Paleoclimatology of laminated sediments.

Application of stable isotopes of carbon, hydrogen and nitrogen in fossil fuel research, for example to monitor thermal maturation of organic matter in coal and oil; organic hydrogen isotope exchange; paleoclimate reconstructions from laminated sediments from the Santa Barbara Basin off California, for example to document pre-historic flood events that were of far greater magnitude than documented Southern California 20th century flood events. Development, production, quality testing, and distribution of (1) organic hydrogen and carbon stable isotope reference materials for irm-GCMS and of (2) Indiana Zinc that converts water-hydrogen to elemental hydrogen for the mass-spectrometric determination of D/H ratios.

Jeffrey White

Professor, Public and Environmental Affairs,Adjunct Professor, Geological Sciences. Biogeochemistry, Aquatic chemistry, Chemical limnology.

Cycling of elements in aquatic and terrestrial systems. Potential impact of human activity on element cycles, for example on cycling of sulfur, iron, manganese, and carbon in lake ecosystems of northeastern North America. Biogeochemical cycling of elements at sediment/water interfaces in fresh water systems and within soils of agricultural systems, with emphasis on nitrogen, phosphorus, carbon, and sulfur; interdisciplinary research on changes in the biology and chemistry of lake/watershed systems. Methanogenesis and methane cycling in wetlands

Chen Zhu

Professor of Geological Sciences. Geochemistry and isotopes. Thermodynamics and kinetics of chemical reactions. Carbon sequestration. Geochemical modeling.

Microbe-metal-water-sediment interactions in bioremediation systems, for example mineralogical characterization and biogeochemical modeling of uranium reduction pathways in uranium bioremediation. Tracing of complex biogeochemical pathways, using atomic and near atomic scale Field Emission Gun (FEG) Transmission Electron Microscopy and FEG Scanning Electron Microscopy, stable isotopes, aqueous chemistry, and numerical biogeochemical models.

Our state-of-the-art instrumentation can be viewed on slides of the Stable Isotope Research Facility. Read about current graduate students and post-docs and about recent graduates and the titles of their theses. A list of selected recent publications is also available.


Email: Arndt Schimmelmann
Phone: 812-855-7645
Fax: 812-855-7899

Email: Peter Sauer
Phone: 812-855-6591
Fax: 812-855-7899