Indiana University Bloomington

Fall 2003 Colloquia

Monday, September 22, 2003
4:00 pm, G143, Department of Geological Sciences
Dr. Xian-Huan Wen, ChevronTexaco
Geostatistical Simulation of Flow and Transport in Heterogeneous Media: Upscale and Integration of Dynamic Data

Abstract: Geostatistical methods are widely used for modeling spatially vary heterogeneous aquifer properties. Multiple equally likely realizations of aquifer models are constructed and then passed to flow and transport simulations for predictions, as well as for uncertainty assessment. The focus of this presentation is two important issues in such practice: upscale and integration of dynamic data.

Geostatistical models continue to grow in size and complexity. Multi-million or billion cell models need to be scaled up to the size that can be comfortably handled by available flow and transport simulators. Traditional scale up approaches focus only on the computation of equivalent properties, neglecting the importance of coarse grid definition. A selective upscaling procedure is presented. This method determines the coarse grid geometry selectively so that the most consequential features in the fine model are preserved as mush as possible by using a flexible grid generation technique. The equivalent permeabilities at the coarse blocks are then computed. I will also present very briefly, leaving the details for Tuesday, some latest research results on upscaling, including:

1. Generation of flow based coarse grid.
2. The border region for accurate compution of equivalent permeability.
3. Coupled global-local upscaling.
4. Transmissibility based upscaling.
5. Reconstruction of fine scale velocity for transport simulation.

Geostatistical aquifer models must incorporate as much information as possible to reduce the prediction uncertainty. Geostatistical algorithms are best suited for integrating static hard and soft data, such as well data and seismic data, through correlation. Dynamic data such as piezometric head, tracer breakthrough curves, and concentration, etc., are nonlinearly related to aquifer properties through flow and transport equations. The integration of such dynamic data typically requires the solution of inverse problem. An efficient geostatistically-based inverse technique, called Sequential Self-Calibration method, will be presented. SSC method iteratively updates the previously generated geostatistical models to match dynamic data while preserving the underlying geostatistical features of the model. Applications of the SSC method for integrating steady-state head data, interference test data, tracer breakthrough curves, and tracer concentration distribution data will be presented.

Tuesday, September 22, 2003
12:00 pm, S201, Geological Survey
Dr. Xian-Huan Wen, ChevronTexaco
Gridding and Upscaling of Geologically Complex Systems: Recent Progress

Abstract: Recent advances in geostatistical aquifer modeling make it possible to construct very complex geological systems with cross-bedding, channeling and mixture of different features. These complex models are very difficult to upscale using currently available conventional techniques resulting in significant error in upscaling. In this seminar, the limitations of current approaches are discussed first and a variety of approaches designed for upscaling complex geological systems for flow simulation are presented. These includes flexible flow-based grid generation; extended local, global and quasi-global techniques for the calculation of equivalent permeability; transmissibility based upscaling, and reconstruction of fine grid velocity model from coarse model for transport simulation.

The detailed procedure of each technique is presented with discussion of the impacts on upscaling results. The results presented illustrate the capabilities of existing upscaling procedures and demonstrate the levels of accuracy attainable using the various approaches.

Wednesday, September 24, 2003
4:00 pm, G143, Department of Geological Sciences
Dr. S. K. Acharyya, Jadavpur University, Calcutta, INDIA
Role of Holocene sea level rise and delta sedimentation in mobilization of arsenic to groundwater: examples from W. Bengal, India, Bangladesh and Vietnam

Abstract: The low-land basin of the rivers Ganga, and Brahmaputra, in the Bengal Basin is entrenched on the Pleistocene terraces during the terminal Pleistocene low-stand setting. These Pleistocene uplands and their cover are oxidised and free of arsenic problem. Rapid sea-level rise and contemporaneous high rate of sediment discharge from the fast eroding Himalayas induced delta sedimentation over low-land basin since around 10,000 yr. B.P. The arsenic bearing aquifers are mainly confined to these sediments. Similarly in the Red and Mekong river deltas in Vietnam, shallow Quaternary aquifers are arsenic affected. The source of arsenic is dispersed. Pyrite or arsenopyrite is absent or very rare in aquifers from the Bengal Basin. Extreme rarity of pyrite in aquifer and very low concentration of sulfate in groundwater goes against the pyrite oxidation hypothesis. Arsenic gets scavenged and adsorbed in dispersed phases of hydrated-iron-oxide, which are preferentially entrapped as sediment coatings on organic rich, argillaceous floodplain and delta sediments. Mobilization and release of arsenic to groundwater is caused by reductive dissolution of HFO and ion exchange processes involving HFO, phosphate, carbonate. Iron-rich groundwater (Fe > 1 mg/L) generally results due to activities of Fe-reducing bacteria, which preferentially reduces least crystalline HFO phases. That reduction of HFO is common and intense in the Bengal Basin is shown by high concentration of dissolved iron (9-36 mg/L). Situation is comparable in the Red and Mekong river deltas in Vietnam. Dissolved iron concentration in groundwater is generally low (<1 mg/L) in the Ganga Alluvial Plain, upstream of the Bengal basin, thus bio-geochemical conditions are generally unfavourable to trigger release of arsenic to groundwater. Ironically both in Bengal and Vietnam switching to groundwater as source of drinking water and irrigation, which reduced child mortality and ushered in 'green revolution', uncapped arsenic 'black-box'.

Monday, September 29, 2003
4:00 pm, G143, Department of Geological Sciences
Dr. Julie Bartley, University of West Georgia
The carbon cycle before skeletons: Carbon cycle linkages and the marine carbon reservoir

Abstract: The Proterozoic C-isotopic record reveals two distinct, yet interrelated trends: (1) a stepwise increase in average 13C from ˜0‰PDB in the late Paleoproterozoic to >+5‰ in the Neoproterozoic, and (2) a concomitant increase in the magnitude of isotopic excursions. Steady state and non-steady state models suggest that these fundamental changes are best explained by a combination of evolving burial fluxes and a secular decrease in the size of the marine dissolved inorganic carbon (DIC) reservoir. DIC reservoir size affects both the sensitivity of the isotopic system to biogeochemical perturbation and the steady state relationship between organic carbon (Corg) and carbonate carbon (Ccarb) fluxes, allowing elevated isotopic compositions to be sustained for geologically long time spans. This dependence on DIC reservoir size provides, for the first time, a direct linkage between changing carbonate precipitation styles and the marine C-isotope record and may therefore help to constrain estimates of Proterozoic pCO2.

Tuesday, September 30, 2003
12:00 pm, S201, Geological Survey
Dr. Julie Bartley, University of West Georgia
Life at high [DIC] - carbonate platforms, taphonomy, and carbon cycling

Abstract: A variety of theoretical, geological, petrographic, and isotopic data suggest that the inorganic carbon content (DIC: CO2, HCO3-, CO32-) of the Precambrian atmosphere-ocean system was higher than modern [DIC]. The effects of changing [DIC] can be recognized in carbonate precipitation rates and styles, in the taphonomy of microorganisms, and in the carbon isotopic record. Further, experimental data suggest that microbial biogeochemical cycling of carbon may also have been different from that of modern communities. The most striking effects of the evolving carbonate reservoir are observed in the style of Precambrian carbonate precipitation.

During the Archean and Paleoproterozoic, abiotic, macroscopically crystalline carbonate is abundant in both subtidal and peritidal environments. The Mesoproterozoic boasts a variety of slowly-lithifying and rapidly-lithifying textures, often in close spatial proximity. By the late Neoproterozoic, seafloor precipitates are virtually absent, supplanted by micritic carbonate textures, except where associated with highly evaporitic conditions or Neoproterozoic glacial deposits. These rapidly-precipitating carbonate textures open the door for spectacular microfossil preservation in sediments replaced by early diagenetic chert.

These changes in [DIC] are also reflected in the carbon isotopic composition of organic matter, which records ancient carbon isotope fractionation by primary producers. As a result, the carbon isotopic composition of modern microbial mats (~-14‰) differs substantially from that of their Proterozoic counterparts (~-30‰). Modern microbial mats grown in the laboratory under normal and elevated [DIC] showed a similar distribution of 13C. Under experimental conditions, 14C-uptake experiments relate high [DIC] to elevated rates of carbon metabolism and slower turnover of organic matter in benthic microbial community, suggesting that biogeochemical cycling also evolved with the marine carbon reservoir.

[CANCELLED] Monday, October 6, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker: Dr. Richard Goldfarb, United States Geological Survey
Paper: Orogenic gold and geologic time: a global synthesis
Title: Gold through Space and Time

[CANCELLED] Tuesday, October 7, 2003
Brown Bag
Time and Location 4:00 pm, S201, Geological Survey
Speaker Dr. Richard Goldfarb, United States Geological Survey
Title Metallogenic evolution of accretionary orogens: The Alaskan example

Friday, October 10, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Peter Heaney, Pennsylvania State University
Title Diamonds from Heaven or Hades? The Carbonado Conundrum

Monday, October 13, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Thomas Algeo, University of Cincinnati
Middle and Late Devonian global events: The role of land-plant evolution and intensified pedogenesis

Abstract: The Middle to Late Devonian Period was characterized by major changes in the terrestrial biosphere, e.g., the evolution of trees and seed plants and the appearance of multi-storied forests, as well as in the marine biosphere, e.g., an extended biotic crisis that decimated tropical marine benthos, especially the stromatoporoid-tabulate coral reef community. Teleconnections between these terrestrial and marine events are poorly understood, but a key may lie in the role of soils as a geochemical interface and the role of land plants in mediating weathering processes at this interface. The effectiveness of terrestrial floras in weathering was significantly enhanced as a consequence of increases in the size and geographic extent of vascular land plants during the Middle to Late Devonian. In this regard, the most important paleobotanical innovations were (1) arborescence (tree stature), which increased maximum depths of root penetration and rhizoturbation, and (2) the seed habit, which freed land plants from reproductive dependence on moist lowland habitats and allowed colonization of drier upland and primary successional areas. These developments resulted in transient episodes of intensified pedogenesis (soil formation) and to large, permanent increases in the thickness and areal extent of soils. Enhanced chemical weathering led to increased riverine nutrient fluxes that promoted development of eutrophic conditions in epicontinental seaways, resulting in algal blooms, widespread bottomwater anoxia, and high sedimentary organic carbon fluxes. Such disturbances were inherently transient in character owing to (1) reduced fluxes of riverine nutrients as soils matured and stabilized, and (2) negative climatic feedbacks, i.e., global cooling associated with drawdown of atmospheric CO2, causing reduced rates of chemical weathering in pedogenic environments. The role of soils as a geochemical interface between the terrestrial and marine biospheres has received insufficient attention, yet pedogenic weathering rates are a fundamental control on bionutrient availability and, hence, an important influence on patterns of evolution and extinction in marine ecosystems.

Tuesday October 14, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker Dr. Thomas Algeo, University of Cincinnati
REDOX FACIES AND SEQUENCE STRATIGRAPHY OF UPPER PENNSYLVANIAN CYCLOTHEMIC CORE SHALES FROM THE MIDCONTINENT REGION

Abstract: High-resolution (cm-scale) geochemical analysis of Upper Pennsylvanian cyclothemic core shales provides insight on paleoredox conditions of the Late Pennsylvanian Midcontinent Seaway. Redox facies were assessed on the basis of ichnofabric and redox-sensitive trace-element (RSTE) enrichment patterns: dysoxic conditions are indicated by the presence of bioturbation and low TOC and RSTE concentrations; anoxic conditions by the absence of bioturbation and increased TOC and RSTE concentrations. Anoxic samples were further assignable to nonsulfidic versus sulfidic (i.e., euxinic) facies depending on degree of RSTE enrichment and patterns of TOC-RSTE covariation. Paleoredox analysis of a typical core shale indicated a sharp decline in benthic O2 levels above the base of the black shale (0 cm), persistent euxinia in the lower to middle black shale (~5-35 cm), fluctuating nonsulfidic to sulfidic anoxic conditions in the upper black shale (~35-50 cm), and uniformly dysoxic conditions in the overlying gray shale.

Cyclothemic core shales were deposited during glacio-eustatic highstands of the Late Pennsylvanian Midcontinent Seaway, the high-frequency climato-environmental dynamics of which can be assessed on the basis of geochemical, petrographic, and sequence stratigraphic analyses. For example, the Hushpuckney Shale Member of the Swope Formation exhibits distinct first-order relationships among major components (organic C, authigenic sulfides and phosphate, detrital siliciclastics), trace-element redox proxies (Mo, U, V, Zn), and ichnofabric features that are indicative of a eustatic control. Petrographic features suggest that the base and top of the black shale facies mark transgression and regression of the pycnocline across the study area, and the first-order peak in TOC and other variables at 17-25 cm is interpreted as the maximum flooding surface (MFS). Organic petrography revealed a sharp decline in the proportion of macerals of terrestrial origin (i.e., vitrinite and inertinite) in the middle of the black shale submember (~28 cm). The abrupt shift in dominant maceral types suggests major climatic change associated with the early stages of sea-level regression, from warm and humid conditions favoring development of paralic coal swamps to cooler and possibly dryer conditions that reduced the export of terrestrial organic matter to the Midcontinent Seaway. Simultaneously, reduced freshwater runoff may have weakened the marine pycnocline and enhanced upwelling-driven productivity.

Monday, October 20, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Roger Cuffey, Owen Award Winner, Pennsylvania State University
Battle Wreckage, Bryozoans, and Artificial Reefs

Abstract: Geology frequently affects battles, but conversely a few battles may contribute eventually to the geology/paleontology of certain sites.

Recent years have seen the intentional initiation of artificial reefs by sinking a variety of hard substrates (ships, cars, concrete-blocks, tires) into shallow warm waters. Naval and military operations — particularly in the Pacific in Word War II — left much metal wreckage in such habitats. In the ensuing years, colonial organisms have encrusted this debris, and grown into small but typical reef covers and masses. If conditions remain favorable long into the future, these could eventually become sizeable reefs. The same species and communities characterize these unintended artificial reefs as are responsible for the natural reefs across that region; stony corals, bryozoan crusts, and calcareous algae are evident, interspersed with soft corals, orgonians, sponges, and algae. Steel ship hulls support prolific diverse growth, as at Truk (1944) especially, but also on Guadalcanal (1942) and Saipan (1944). Contemporaneous aluminum airplane wings hold noticeably less growth, hence appear partially bare, presumably due to the different metal substrates.

Wreckage in deeper, colder, or brackish water exhibits the same reductions in diversity and abundance as seen in natural bioherms in such environments. Ships under tropical deep ocean waters host only a few gorgonians and sponges (Yorkto\vn, 1942; Ironbottom Sound, 1942); those at similar depths in higher latitudes even fewer (Bismarck, 1941; also Titanic, 1912). Shipwrecks on warm-temperate continental shelves can acquire many encrusting cheilostome bryozoans (Monitor, 1862, Cuffey and Fonda'82 '83; U-boat from Adriatic, 1918, in Vienna museum). Equipment in a brackish estuary or lagoon supports occasional crusts ofeuryhaline bryozoans (Chesapeake Bay), as well as soft algae, or may bear virtually no reefal invertebrates (Arizona, 1941).

Finally, battle debris can contribute to certain local geologic records by being incorporated into reefal sediments, then cemented as beachrock (Eniwetok Atoll, 1944).

Monday, October 27, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker TBA
Title TBA

Tuesday, October 28, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker TBA
Title TBA

Monday, November 10, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Hope Jahren, Johns Hopkins University
Title New Insights into Arctic Paleoclimate during the Eocene From Stable Isotope Analyses of Plant Fossils

Tuesday, November 11, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker TBA
Title TBA

Monday, November 17, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker TBA
Title TBA

Tuesday, November 18, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker TBA
Title TBA

Monday, November 24, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Yemane Asmerom, University of New Mexico
Title: DISCOVERING THE RECENT PAST: New horizons in high-precision chronology of rapid geological change

Tuesday, November 25, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker Dr. Yemane Asmerom, University of New Mexico
Title: WHO KILLED WOOLY?

Monday, December 1, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Richard Miller, Kansas Geological Survey
Title TBA

Tuesday, December 2, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker Dr. Richard Miller, Kansas Geological Survey
Title TBA

Monday, December 8, 2003
Colloquium
Time and Location 4:00 pm, G143, Department of Geological Sciences
Speaker Dr. Howard Feldman, ExxonMobil Upstream Research Company
Title: ESTUARINE FACIES MODELS FROM THE CRETACEOUS CLEARWATER FORMATION AT COLD LAKE, ALBERTA, CANADA

Abstract: The Cold Lake area contains over 25 billion barrels of in place bitumen and presents a unique opportunity to study fluvial-to-estuarine facies transitions within incised valley fills (IVFs), because of the high-density of well logs and cores available. Approximately 700 wells were used to map at least nine incised valleys from updip fluvial IVFs to downdip valley terminations over a distance of 70 km. All fluvial-to-estuarine IVFs thin basinward and pinch out into marine mudstones; none of the valleys apparently fed deltas or beaches. This contrasts strongly with the traditional valley termination models in which incised valley rivers feed lowstand deltas or beaches.

There are two general depositional patterns to the Clearwater Formation IVFs: The first type of IVF consists of braided river to tidal bar IVFs. Updip trough-cross stratified, braided fluvial sandstone grades downdip into muddy tidal bar facies, which are characterized by coarsening upward parasequences, common mud drapes, and estuarine trace fossils. Tidal bar facies become increasingly muddy downdip. The second type of IVF consists of braided fluvial sandstone updip and coarsening upward, estuarine delta parasequences downdip. Delta parasequences are characterized by interbedded thin sandstone and mudstone beds, abundant current ripples, and a restricted trace fossil assemblage. In all IVFs there is a downdip increase in trace fossil diversity and a decrease in the sand/shale ratio as the IVF's thin. The IVFs are incised into non-reservoir open marine, offshore shale, very fine-grained shoreface sandstone, and brackish bay shale.

Reservoir heterogeneity at Cold Lake is due to nesting of IVFs and facies transitions within the IVFs. Significantly, there are no downdip exploration targets because none of the valleys are associated with valley-termination sands, such as beach or delta facies. Virtually all of the sand was apparently trapped within the estuaries, forming the main reservoir units in the Cold Lake area.

Tuesday, December 9, 2003
Brown Bag
Time and Location 12:20 to 1:10 pm, S201, Geological Survey
Speaker Dr. Howard Feldman, ExxonMobil Upstream Research Company
Title: TBA