Indiana University Bloomington

Spring 2003 Colloquia

Tuesday, January 21, 2003
Owen Award Lecture
John Bubb, Exxon Exploration Co. (Retired)
"Some Adventures and Misadventures as a Petroleum Explorationist"

Monday, January 27, 2003
Indiana Geological Survey

Monday, February 3, 2003
Jared Morrow, Univ. of Northern Colorado
"The Catastrophic Alamo Event: Record of an Oceanic, Late Devonian Extraterrestrial Impact, Nevada"

Tuesday, February 4, 2003
Brown Bag Seminar
Jared Morrow, Univ. of Northern Colorado
"Late Devonian Event Stratigraphy and Mass Extinction, Western U.S."

Friday, February 7, 2003
Brown Bag Seminar
Roger Summons, Massachusetts Institute of Technology
"Biomarkers: Molecular Signatures for Early Life"

Monday, February 10, 2003
Jean Bahr, University of Wisconsin - Madison
Birdsall-Dreiss Lecture: "Groundwater as an Ecosystem Resource"
4:00 pm in Geological Sciences GY143

Monday, February 24, 2003
Henk Kooi, Free Univ. Netherlands

Thursday, February 27, 2003
Dr. Brian Mailloux, Columbia University
"The Transport and Activity of Bacteria in the Columbia Aquifer, Oyster, Virginia"
4:00 p.m., Room GY126

High levels of contaminants including radionuclides (e.g. U, Pu, and Cs) and metals (e.g. Cr, Hg, and Pb) are found in the ground water at the Department of Energy Facilities. Microorganisms could potentially be utilized to immobilize the contaminants in situ. The goal of this talk is to examine how heterogeneity in aquifer properties and heterogeneity in bacterial properties would affect remediation. Results will be discussed from experiments performed at the laboratory and field scale.

Friday, February 28, 2003
Brown Bag
Dr. Brian Mailloux, Columbia University
"Microbial Controls on Redox Processes in Aquifer Systems"
12:20 p.m., S201 (The Patton Room)

It is becoming apparent that microbial processes control the aqueous geochemistry of aquifer systems. Microbial processes may therefore control the availability of clean ground water for drinking. This talk will outline the molecular, laboratory, and field-scale techniques that can be utilized to better understand microbial processes in aquifer systems and some questions that still need to be answered.

Wednesday, March 5, 2003
Talk by Derek Fullerton: "The Where Why How and When of Diamond Exploration"
9:05 a.m., GY 338

Thursday, March 6, 2003
Talk by Dick Gibson: "Gravity and Magnetics in Hydrocarbon Exploration"
8:00 a.m., GY 447

Friday, March 7, 2003
D.O.G.S. Days: IU Graduate & Undergraduate Geoscience Students
Monday, March 10, 2003 4:00 p.m., Room GY143

Annette Summers Engel, University of Texas at Austin
"Biogeochemical cycling in chemoautotrophically-based terrestrial ecosystems"

While chemoautotrophic microorganisms are found in nearly every environment on Earth, they are most abundant in dark habitats where competition with photosynthetic organisms is eliminated. Sulfidic aquifers, particularly those in karst regions where groundwater discharges into cave passages, serve as important sites to study microbial sulfur cycling and chemoautotrophy in the terrestrial subsurface. The geochemistry of a sulfidic cave system, its sulfur-based microbial community, and nutrient cycling will be discussed.

Tuesday, March 11, 2003
Brown Bag
Annette Summers Engel, University of Texas at Austin
"The Role of Microorganisms in Cave Formation"
12:20 p.m., S201 (The Patton Room)

Earlier speleogenetic models held that cave development proceeds due to chemical and hydrologic controls, while the contribution of biological controls has largely been misunderstood or ignored. Laboratory- and field-based techniques will be described that indicate microbial ecosystems do contribute to cave formation through the generation of metabolic waste products. This new recognition of microbial processes fundamentally changes the model for cave formation and provides a better understanding of the causal factors for subsurface porosity development.

Monday, March 24, 2003
Chen Zhu, University of Pittsburgh
"Hydrogeological responses to paleoclimatic changes during late Pleistocene and Holocene, Black Mesa basin, Arizona"
4:00 p.m., Room GY143

Despite enormous efforts to reconstruct paleoclimatic changes, records on the responses of groundwater systems to such changes are rare. The groundwater basin at Black Mesa, Arizona provides a record of hydro- geological responses to natural climate variability in late Pleistocene to Holocene. A quantitative understanding of paleohydrogeologic response is critical for studies of hydrological processes and global environmental changes, as well as for the safety of nuclear waste repositories and management of water resource. In this study, paleorecharge and paleogroundwater flow patterns of the past 31 k.y. were reconstructed for the Navajo aquifer in the Black Mesa basin. 14C dating of groundwater was combined with numerical simulation of groundwater flow and 14C transport. Results show that paleorecharge rates varied significantly with time. The temporal variations correlate well with 18O and D records of paleotemperatures and noble gas data as well as with other climate proxies in the Four Corners area. Recharge rates were two to three times higher than today during the late Pleistocene when inferred annual mean temperatures were 5–6°C cooler, but about 50% lower during early to mid-Holocene when inferred summer temperatures were 2–4°C warmer. The pulse of the highest estimated recharge between 14 and 17 ka was possibly related to the northward migration of the southern branch of the split jet stream. An understanding of the magnitude of hydrogeological responses to natural climate variability in the recent geological past is central to testing our ability to predict hydrologic changes due to upcoming climate changes.

Tuesday, March 25, 2003
Brown Bag
Chen Zhu, University of Pittsburgh
"On–going and Planned Research –with a tale of two rates of feldspar dissolution"
12:20 a.m. - 1:10 p.m., The Patton Room (S201)

I will spend the first half of this brown-bag seminar discussing my research programs on (1) feldspar dissolution kinetics; (2) trace element partitioning and bacteria-water-rock interactions; (3) applications of coupled reactive transport models to sedimentary, hydrothermal, and environmental systems; and (4) paleoclimate and hydrology. The second half will describe my on-going NSF and DOE-funded research on feldspar dissolution.

My study first established feldspar dissolution rates in well-studied aquifers specifically, the Navajo sandstone in Arizona and the Santa Fe group in New Mexico. The in situ rates, derived from inverse mass balance geo- chemical modeling, are 107 times slower than lab rates. The feldspar-clay-water interface is being examined using a near atomic scale field emission gun (FEG) scanning electron microscope (SEM) and an atomic scale transmission electron microscope (TEM, collaboration with David Veblen of Johns Hopkins). SEM shows that feldspar grains are coated with patchy kaolinite and a continuous layer of smectite/illite. Using TEM, we discovered a 10-nanometer thick leached amorphous layer on all K-feldspar grains, the first time this has been observed in near neutral pH solutions, and indicating preferential leaching as a dissolution mechanism, even at near neutral pH.

These field and laboratory data are being combined with modeling and theoretical calculations to systematically test the numerous hypotheses put forward to explain the discrepancy between the field and lab rates. A simple explanation is still elusive, but we suspect, at the moment, the slow kinetics of secondary mineral precipitation may represent the differing conditions in natural from laboratory settings.

Thursday April 17, 2003
Brown Bag
Bob Dodd, Indiana University
"China –Its Wall, Gorges, Spires, and Clay Soldiers"
Refreshments provided courtesy of Joann Dodd
12:20 in room 518

Denny Hubbard, Oberlin
Monday, April 28, 2003

George Stanley, Univ. of Montana