Thursday, January 31, 2013
Dr. Heidi Anderson, Western Carolina University
Title: Carboniferous depositional systems and glacial cycles in southern Bolivia
The Late Carboniferous Macharetí and Mandiyutí groups, deposited in the Tarija-Chaco Basin of southern Bolivia, record a complex succession of glacially influenced siliciclastic rocks providing important information about the climatic history of western Gondwana. Stratigraphic and sedimentologic data from these units indicate at least six glacial intervals during the Late Paleozoic Ice Age in western Gondwana, recording one in the Late Devonian, one in the Mississippian, and at least four in the Pennsylvanian. Glacial cycles are recorded as thick massive diamictite beds with polished, faceted, and striated clasts, rare glacial pavements, and dropstones that denote advances of the glacial system into the basin. Interbedded sandstone units contain large trough crossbeds, paleosols, and resedimented facies of fluvial and deltaic systems that represent glacial retreat and interglacial periods. Deposition throughout this time is greatly influenced by the Late Devonian-Mississippian Chañic Orogeny which likely contributed to the complex stratigraphy and limited extent of Late Devonian and Mississippian units. Glacial evidence decreases to the north within the Tarija-Chaco Basin and through time following the rotation of Gondwana.
Thursday, February 7, 2013
Dr. Ronny Pini, Stanford University
Title: Determination of Capillary Pressure and Relative Permeability Curves from Core-Flooding Experiments
Geological systems are complex and so are the processes that determine the distribution of two (or more) immiscible phases within their porous structure; nevertheless, an empirical relationship between the capillary pressure and saturation, the capillary pressure function, provides the foundation for the theory of multiphase flow in porous media. The simultaneous existence of at least two fluids in a porous rock further implies that the ability of each fluid to flow is reduced by the presence of the other and a so-called relative permeability function has been introduced. When coupled to the continuum-scale equations of motion, these two characteristic curves allow for a description of multiphase displacement processes in a variety of natural settings that are related to a wide range of applications, thus including the storage of carbon dioxide into deep saline aquifers. I will present results from a newly developed technique that allows for the simultaneous measurement of capillary pressure and relative permeability drainage curves during a core-flooding experiments. Measurements have been obtained on a Berea Sandstone core by using three different fluid pairs, namely gCO2/water, gN2/water and scCO2/brine: the experiments carried out at moderate pressures can be compared directly with results for gas/liquid pairs reported in the literature and they set the benchmark for the experiment at a higher pressure, where CO2 is in the supercritical state. Hereby, I will seek to explain and reconcile some of the uncertainties and inconsistencies related to scCO2/brine relative permeabilities and capillary pressures. Additionally, the proposed experimental technique allows obtaining Pc-S relationships on mm-scale subsets of the rock core by combination with saturation measurements from X-ray CT scanning; these are of high relevance as they directly and non-destructively quantify small-scale capillary heterogeneity in these systems. These measurements provide independent confirmation that sub-core scale capillary heterogeneity plays an important role in controlling saturation distributions during multiphase flow. The spatial variation of the capillary pressure curve can be described by means of so-called scaling factors, which are derived from scaling-laws based on the concept of similar media (such as the Leverett J-Function), and which can be related to other relevant petrophysical properties of the rock, such as porosity and permeability. Additional diagnostic information are obtained about the inherent heterogeneity of these natural porous systems, thus setting a firm point of departure for developing and testing methods for up-scaling capillary pressure curves.
Thursday, February 14, 2013
Dr. Yvette Kuiper, Colorado School of Mines
Title: Himalayan-type escape tectonics along the Superior Province margin in Manitoba, Canada
The Superior Boundary Zone separates the Archean Superior Province to the southeast from the Paleoproterozoic Reindeer Zone of the Trans-Hudson Orogen to the northwest. In northern Manitoba, late convergence along the zone in the Paleoproterozoic has previously been interpreted in terms of a promontory model, where the Superior Province indents the Reindeer Zone towards the northwest. A modified promontory model will be presented that includes a WNW transport direction of the Superior Province and lateral escape of a segment of the Superior Province (the Split Lake Block) along the northern margin of the promontory. The model is based on the kinematics of an array of shear zones along the Superior Boundary Zone that are interpreted as having been active concurrently. Particular attention will also be paid to strain partitioning along selected shear zones.
Thursday, February 21, 2013
Brent Breithaupt, Bureau of Land Management Regional Paleontologist
Title: Photogrammetric Ichnology: State-of-the-Art Digital Data Analysis of Dinosaur Footprints and Other Paleontological Resources in North America and Europe
Vertebrate trace fossils reflect the complex interrelationship between an animal and the substrate. Digital data collection provides an excellent tool for capturing an incredible wealth of information provided by ichnofossils. Close-range photogrammetry is one of the easiest and most cost-effect digital data collection techniques and forms the basis for photogrammetric ichnology. Three-dimensional image datasets created from digital photography can provide a permanent digital record of fossil tracks (including the creation of digital type specimens) and tracksites and is a non-invasive method to obtain 3D data for assessment. Photogrammetry is an objective recording and analysis method, which provides a visual, quantifiable baseline to evaluate track-bearing surfaces. It has been especially useful in remote locations of Europe, Asia, Africa, and United States. Not only do these datasets support accurate visualization of the fossils, they can also be used to make accurate measurements, as well as highly accurate solid, three-dimensional models of the surface. As 3D terrain surfaces or point clouds created from photogrammetric documentation may contain thousands of very accurate x, y, and z coordinates, researchers can measure various track and trackway dimensions at a submillimeter level. In addition to traditional ichnological measurements, higher-level mathematical analyses may be conducted on the 3-D data. These calculations can automatically quantify areas of surface curvature, roughness, slope and other morphometric characteristics. Because these calculations are conducted by algorithms within the software, human bias is greatly removed if not eliminated. Utilizing this type of data analysis, unbiased morphological correlations of various ichnofaunas (e.g., Jurassic tracks from Wyoming, Utah, Scotland and England) can be made and footprint data normalized (e.g., converting convex hyporelief forms to concave epirelief) for comparison purposes. Digital datasets are stored easily, provide a permanent record, are readily shared, and are currently helping to unravel numerous ichnologicalcomplexities at tracksites throughout the world. Advances to software and cameras allow this technique to be used on paleontological specimens of all shapes and sizes in the field, lab, and collections. Subjects can vary from an isolated tooth to an entire bonebed or from a single fossil footprint to and entire tracksite. Because of the computational power of the new generation of photogrammetric software, hundreds of photographs can be processed at once and stitched together allowing for the documentation of subjects in the round. Several studies have been conducted comparing LIDAR and photogrammetry methods. Recent comparisons demonstrate that photogrammetric point clouds can be generated at a level that meets or exceeds the instrument specifications for the LIDAR unit used in the comparison. Virtually every geologist has the basic equipment (i.e., scale bar and camera) necessary to successfully create scientifically useful photogrammetric point cloud data. These data can also be used for better science–based management decisions, in accordance with current federal paleontological legislation, which requires that state-of-the-art methodologies be used in the documentation of paleontological resources.
Thursday, February 28, 2013
Dr. Anatoly Zaitsev, St. Petersburg State University
Title: “Critical metals” in phoscorite-carbonatite complexes: Examples from Kola province (Russia) and Gregory rift (Tanzania)
Almost all of the Earth’s igneous rocks are composed of silicate minerals. Carbonatites are the main exception to this rule. They are composed predominantly of carbonate and were first recognized as igneous rocks in the 1930s but not universally accepted until the Oldoinyo Lengai volcano in Tanzania erupted carbonatite lavas in the 1960s.
Although carbonatites form only a minor proportion of the earth’s crustal rocks, these unusual rocks are of both academic and economic importance. By combining mineralogical, geochemical and petrological studies of carbonatites much valuable information can be obtained on the origin of carbonatites, on the differentiation of carbonatite magmas, and on processes occurring within the mantle.
Some carbonatites are associated with complex segregations of apatite, magnetite, forsterite, phlogopite and calcite (or dolomite). These rocks, termed phoscorites, occur mainly in Russia and in only a few other localities world-wide. Two of these complexes, Kovdor in Russia and Phalaborwa in South Afrika, host a diverse range of mineral resources and have been commercially exploited for magnetite, apatite, baddeleyite, Cu and PGE.
Phoscorites and carbonatites contain some key accessory minerals (pyrochlore, zirconolite, baddeleyite, burbankite group minerals) that are rich in rare metals such as Nb, Ta, Zr and Hf, and rare earth elements. These minerals occur in both the magmatic rocks and their associated metasomatic (or hydrothermal) rocks. Thus, they crystallize over a wide range of temperatures and magma/fluid compositions, and their chemical composition reflects, and can therefore monitor, the evolutionary path of the primary magma.
Most carbonatite complexes, about 500 occurrences world-wide, contain only intrusive carbonatites. Just 40 occurrences have extrusive carbonatites and only a few examples of these contain carbonatite lavas.
A notable example of an volcanic carbonatite is the Oldoinyo Lengai volcano from the Gregory Rift in northern Tanzania. This is the only volcano ever to have been seen to erupt carbonatites. The carbonatites are also unusual in terms of their mineralogy and chemical composition. They contain the carbonates nyerereite Na2Ca(CO3)2 and gregoryite Na2CO3 as major minerals with subordinate amounts of sylvite and fluorite.
Tuesday, March 5, 2013
Dolores van der Kolk, Bureau of Economic Geology, University of Texas at Austin
Title: High-latitude marine-continental transitions in a greenhouse world: Reconstructing Late Cretaceous Arctic shorelines of northern Alaska
Deltaic, shallow marine, and shelf facies of the Upper Cretaceous (Santonian- Maastrichtian) Schrader Bluff Formation (Fm) are exposed along the Colville River at Shivugak Bluffs on the eastern margin of the National Petroleum Reserve—Alaska. Along with the interfingering distal coastal plain deposits of the Prince Creek Fm, these units provide an outcrop analogue for nearby shallow, viscous-to-heavy oil hydrocarbon reservoirs on the North Slope (e.g., Milne Point, Orion, and Polaris fields). Altogether, 650 m of continuous stratigraphic section were measured through these understudied, world-class outcrops (11 km long; 90–120 m high) as part of a multiyear investigation of this high-latitude marine-to-continental transitional system. My primary objectives are: 1) to document high-resolution, vertical and lateral variations in facies and stratal geometries to produce a series of paleoenvironmental reconstructions for this paleopolar Arctic shoreline (~83° N) and 2) to document the numerous sandbodies (>25 m thick) with complex bedforms intercalated with mudstones (~40 m thick) to help modify and improve reservoir models.
Due to the remote location, restricted access, subvertical cliffs, and the width of the immediately adjacent Colville River a GigaPan EPIC Pro System was used to photo-document the sedimentary structures, sedimentary architecture, and stacking pattern in the outcrop belt. GigaPan robotic panhead hardware and Stitch.Efx stitching software renders high-resolution imagery of these frontier outcrops and fills a gap where locations are too steep for a geologist to work. Subsequently, GigaPans provide geologists with a virtual field trip where facies and lateral facies relationships can be explored further. For example, sand, shale, and bedset geometries can be examined and interpreted after returning from the field, and key stratigraphic surfaces and stacking patterns can be documented. GigaPan imagery also provides a snapshot in time of outcrops that are highly susceptible to rockfalls, sloughing, and seasonal water-ice erosion.
Preliminary results from combined sedimentology and ichnology suggest that the Schrader Bluff Fm at Shivugak Bluffs preserves a shallow marine, storm-dominated succession. This interpretation is based on the abundance and preservation of hummocky cross-stratification relative to less abundant trough cross-stratification and symmetric “wave” ripples. Transitional environments include lagoons, bays, delta fronts, and distributary mouth bars, along with potential barrier islands, tidal inlets, tidal flats and estuaries. The interfingering Prince Creek Fm preserves braided and meandering channels and associated organic-rich floodplain deposits. This study will ultimately produce a model for high-latitude clinoform topsets deposited during Late Cretaceous greenhouse conditions and provide climate modelers and other scientists with additional data on paleopolar shorelines.
Thursday, March 7, 2013
Dr. Peter Flaig, Bureau of Economic Geology, University of Texas at Austin
Title: The Late Cretaceous Coastal Plain of Arctic Alaska: Sandy-Splays, Swamps, Soils, and Savagely Surging Streams
The North Slope of Alaska offers scientists world-class Cretaceous outcrops that provide a glimpse into a paleopolar landscape during a greenhouse phase in Earth’s history. Coastal plain sediments of the Campanian-Maastrichtian Prince Creek Formation (PCF) preserve a portion of this high-latitude Arctic ecosystem that fortuitously contains the richest concentration of dinosaur remains documented in the polar regions. Many of these laterally-extensive outcrops also serve as remote yet accessible analogues for nearby hydrocarbon reservoirs. Consequently, investigations into North Slope outcrop belts are not only important to academics who wish to better understand the complexities of this diverse high-latitude greenhouse system, but also to industry personnel who strive to improve reservoir models and increase production.
The PCF is exposed in semi-continuous bluffs along a 90 km stretch of the Colville River northeast of Umiat, Alaska. Near-vertical 30-120 m-thick bluffs contain sandstone, siltstone, shale, mudstone, coal, and ash deposited on a high-latitude (82°–85° N), low-lying, vegetated coastal-plain. Paleoenvironments include tidally influenced meandering and fixed (anastomosed?) rivers, levees, splays, lakes, ponds, swamps, and paleosols. Ash beds (bentonites) are common and many lithologies exhibit trampling by dinosaurs. Spatial relationships and geometries of facies indicate that most deposition took place on crevasse-splay complexes adjacent to trunk channels. Splay complexes were constructed by the lateral migration of meandering distributaries and the vertical filling of fixed (anastomosed?) distributaries. Splay complexes are separated from each other by organic-rich floodplain facies. Compound and cumulative weakly developed soils formed on levees, point bars, splays, and along the margins of lakes, ponds, and swamps. Repeated wetting and drying of soils is evident from soil macro- and micro-morphology.
Dinosaur bone is rarely found in channels; instead, high-density bonebeds dominated by partially articulated to associated juvenile Edmontosaurus sp. remains are encased in muddy alluvium outside of channel margins. Three expansive, well-documented bonebeds contain bone which exhibits little evidence of bone modification (e.g. rounding, weathering, predation, trampling) suggesting short-distance transport and rapid burial. Most bones are in hydraulic disequilibrium with the surrounding silt and clay-rich matrix, and bone size-grading is generally non-uniform. All bonebeds include a basal ripple cross-laminated siltstone containing the largest bone overlain by a distinctive massive mudstone encasing smaller bone, bone-fragments, and sub-parallel aligned comminuted plant fragments. This recurring facies pairing suggests repeated two-phase flow, with deposits forming bipartite couplets similar to hyperconcentrated flow deposits. We propose that exceptional discharge events, driven by seasonal snowmelt in the nearby Brooks Range mountain belt, entrained vast quantities of silt, ash, and mud generating viscous, erosive hyperconcentrated flows that trapped(?), transported, and buried scores of juvenile dinosaurs on distal floodplains adjacent to distributary channels. This unique depositional mechanism likely resulted, in part, from the paleopolar position of Arctic Alaska (82-85° N) during the Late Cretaceous Greenhouse.
Thursday, March 14, 2013
Dr. Kevin Pogue, Whitman College
Title: Flows, Folds, Floods, and Fine Wine: Terroir of the Columbia Basin
The terroir of the Columbia Basin, one of the most important grape-growing regions in North America, is the result of a complex geologic history that includes one of the largest flood basalt provinces on Earth, an active fold and thrust belt, and sediments deposited by the Earth’s largest document floods. Each of these events has played a major role in the formation of the landscape, soils, and climate of a region that today hosts almost 50,000 acres of vineyards. Most of the vineyards lie within one of the basin’s 11 federally recognized American Viticultural Areas (AVAs). The distinctiveness of the wines from each AVA can be attributed, in part, to their unique microclimates and the chemical, thermal, textural, and hydrologic properties of the vineyard soils.
Thursday, March 28, 2013
Dr. George Kraft, University of Wisconsin–Stevens Point
Title: Groundwater Pumping Impacts on Wisconsin Surface Waters with the Central Sands as Case Study
Wisconsin is part of a US region that is hydrologically special. The happenstance of our climate (abundant precipitation) and geology (prevalence of thick, coarse glacial sediments and shallow permeable sandstones and carbonate rocks) have provided a setting where surface waters are often unusually well-connected and well-nourished by groundwater.
Wisconsin has yet to adopt policies that manage groundwater quantity with consideration for surface water health. Thousands of high capacity wells pump water all the time with no control nor even knowledge of what surface waters are being impacted.
One of the regions most developed for groundwater pumping is the Central Sands, where tens of billions of gallons of groundwater is pumped for irrigation annually. This pumping has led to a drying of lakes, wetlands, and headwater streams. This colloquium will explore the history of groundwater development in the central sands, the pumping – impaired waters connection, and the implications for future management.
Tuesday, April 2, 2013
Richard Palin, PhD Candidate at Oxford University
Title: Constraining the structural and metamorphic evolution of the Himalayan-Karakoram-Tibetan orogeny
Tuesday, April 9, 2013
Erik Gulbranson, Postdoctoral Research Fellow, University of Wisconsin–Milwaukee
Title: Paleo-polar environments: biogeochemistry, glaciations, and climate.
Thursday, April 11, 2013
Victoria Petryshyn, Postdoctoral Researcher, University of California–Los Angeles
Title: Stromatolites: Old controversies and new methods
Stromatolites, commonly defined as laminated, lithified organo-sedimentary structures built by microbial mats, constitute some of the oldest putative fossils on Earth. However, The processes that control the different aspects of stromatolite morphology (i.e. form, growth rate, texture, and laminae formation) are poorly understood. Additionally, abiotic structures that mimic “real” stromatolites are known. Processes as common as mineral growth, or as esoteric as paint spatter, or electroplating of metals are now known to create structures indistinguishable from “real” stromatolites at some scales. Furthermore, numerical stromatolite growth models imply that microbial involvement may not be a prerequisite to form such morphologies at all, adding to the confusion about what is a stromatolite, and what is a true microbialite in the rock record. In order to shed some light on the topic, I will present evidence from stromatolites found on the shores of Walker Lake, an alkaline lake in western Nevada. Detailed studies of growth rate (via 14C dating), growth direction, texture, and morphology reveal that the conventional model of stromatolite morphogenesis needs revision. Secondly, I will introduce a new stromatolite biosignature, based on the detrital magnetic signature contained in sedimentary rocks and the inherent ‘stickiness’ of microbial mats. Finally, I will present results from Pavilion Lake in British Columbia, and the Eocene Green River formation that show the utility of lacustrine stromatolites as long-term terrestrial climate archives. Through the measurement of 13C-18O bond ordering in carbon dioxide produced by the dissolution of carbonate in acid (also known as carbonate ‘clumped’ isotope geochemistry), the temperature of formation of stromatolites can be quantitatively determined. Traditional methods of determining the temperature of formation of a carbonate rock rely on knowing both the oxygen isotope ratio of the fluid of formation (something that is almost impossible to distinguish, and thus is frequently assumed), and the oxygen isotope ratio of the carbonate. By using this proxy, it is possible circumvent those issues, and discern the temperature of formation of a carbonate to within 1-3°C. Using this information, the average mean annual air temperatures can be calculated.
Monday, April 15, 2013
Hejiu Hui, Postdoctoral Research Associate, University of Notre Dame
Title: Water in the Moon: It’s been there all along
The Moon was thought to have lost its volatiles during impact(s) of a Mars-size planetesimal with the proto Earth. One of the most important conclusions resulting from the Apollo and Luna missions was that little water was detected in the returned samples or at the surface of the Moon. The view of an anhydrous lunar interior, however, has been challenged by the recent discoveries of hydrogen in picritic glass beads, apatites and olivine melt inclusions. Indigenous water is now thought to be heterogeneously distributed in the lunar interior. This water is thought to have been brought in part through solar wind implantation and meteorite/cometary impacts after the formation of the primary crust.
Here we measured water in primary products of the Lunar Magma Ocean (LMO) thereby by-passing the processes of later addition of water to the Moon through impact events or during mantle overturn as suggested by previous studies. Ferroan anorthosite is the only available lithology that is believed to be a primary product of the LMO. It is generally understood that plagioclase, after crystallization, floated in the LMO and formed ferroan anorthosite as the original crust of the Moon. Therefore, any indigenous water preserved in pristine ferroan anorthosite was partitioned from the LMO. Using Fourier transform infrared spectroscopy, we have measured ~6 ppm of indigenous water as hydroxyl species in plagioclases from the ferroan anorthosite 15415 and 60015. With ferroan anorthosites representing the floatation crust above the crystallizing magma ocean, we calculated the initial water content of the latter to have been ~320 ppm H2O. Water accumulated in the final 2 vol.% magma ocean residuum as crystallization proceeded could reach amounts of ~1.4 wt.%. We therefore show that water has been present in the lunar interior since its earliest history, during magma ocean formation and crystallization. The presence of water in the moon’s interior at such an early stage is difficult to reconcile with the theory that the Moon formed from the debris generated during a giant impact with the proto-Earth. This water can affect the crystallization dynamics of lunar magma ocean and the following mantle cumulate overturn process, and hence the genesis of lunar basalts.