Rudy Lynn Slingerland - US grants

A modelling study to construct a dynamic stratigraphic model of event bed deposition on the Louisiana-Texas continental shelf. Sensitivity tests will help define a set of physically realizable solutions. The main objective is to test the hypothesis that coarse-grained "event" beds are the result ofshort-lived storms. The modelling will attempt to answer questions about the strength of geostrophic flow necessary to form these beds, the source for the sand, regional extent and interval characteristics and the vertical sequence of the event beds in the framework of the frequency of storms and availability of accommodation space on the shelf.

Strata deposited during the globally warm, equable, Cretaceous period preserve the record of a unique natural experiment which will help us better understand the dynamical behavior of the integrated earth system. The stratigraphic record of the Western Interior Cretaceous Seaway (WIKS) provides an unparalleled opportunity for study because of the availability of substantial data sets that are ripe for synthesis and analysis. Using the WIKS as a working "laboratory" we propose to: (1) understand the global climate system and its variability during a period of extreme warmth; (2) validate climate models for conditions substantially different from the present day; (3) determine the oceanographic, biological, and chemical responses of the WIKS across the C/T boundary to both global and regional forcing factors; and (4) better define the links between these seaway responses and the geologic record of the Western Interior Basin. In this study a series of hierarchical atmospheric and ocean model simulations constrained by the diverse WIKS dataset will be performed for three times slices representing different stages of a major second order sea level cycle (Greenhorn cyclothem). For each time slice we will: (1) determine the global paleogeography, paleotopography, sea level, and atmospheric pCO2 from the literature; (2) perform baseline numerical experiments of global climate using the NCAR Community Climate Model (CCM); (3) perform a series of CCM sensitivity experiments to sealevel changes, low versus high topography, variable orbital parameters, and variable pCO2; (4) investigate the sensitivity of the WIKS to CCM variation by using daily wind stresses and evaporation minus precipitation from the CCM runs to drive a three-dimensional, turbulent flow, coastal ocean model; (5) investigate the influence these circulation changes might have on organic carbon production, and carbon and oxygen isotopes by following chemical tracers in the circulation model and developing box models of nutrients, oxygen, and salinity; and (6) test these predictions by assembling lithofacies maps, benthic biofacies/oxygen gradient maps, and maps of inferred temperature, paleosalinity and organic carbon distribution.

9303851 Slingerland This study will investigate the processes of avulsion, i.e., the permanent diversion of flow away from an existing river channel, and the role of avulsion in the evolution of river floodplains and alluvial sedimentary deposits. The approach will be collaborative, focusing on mathematical modelling experiments, and modern and near-modern river floodplains. The project will attempt to address such questions as the causes of avulsion, the processes by which avulsions initiate and propagate through flood basins, the manner in which floodplains subsequently react to avulsion, and the effects of avulsion on the character of floodplain deposits. Because avulsion is an inevitable consequence of floodplain aggradation, it may play a vital, and heretofore underappreciated, role int he evolution of alluvial sedimentary sequences because it is likely to be a major process of deposition instead of merely a mechanism by which old channels are abandoned and new ones formed. When properly understood, avulsions may require modifications in the way we view the origin and role of meander belts, the relative importance of avulsive vs overbank flooding, and the manners in which floodplain deposits are generated.

9526954 Willett The objective of this research is to construct an improved orogenesis model and conduct numerical experiments that will reveal the nature and strengths of feedback between tectonic deformation and surface processes in evolving mountain belts. The experiments will be guided by a dataset of geologic and topographic observations of active mountain belts, collected both from the literature and digital elevation models. To accomplish this objective, two extant surface-processes models (SPMs) will be synthesized, and a new model constructed that accounts for orographic climate, chemical weathering, and alpine glaciation. The macrogeomorphology and exhumation patterns of a few carefully selected mountain belts will be predicted using the coupled model and the results tested against observations. The ultimate outcome of this research should be an improved underqtanding of the nature and strengths of feedback between tectonic deformation and surface processes in evolving mountain belts.

9811860
Slingerland

This study will examine the origin, evolution morphological and sedimentological characteristics of natural levees in alluvial floodplains, concentrating on the upper Columbia River near Golden, British Columbia, and the Saskatchewan River at the Cumberland Marshes, eastern Saskatchewan. Despite common depictions of levees as being relatively simple features, they are quite complex, displaying a wide range of sizes, shapes, slopes, and textural attributes that likely reflect controls of channel and floodplain configurations, channel history, sediment load, flood character and flood history. This three-part investigation will include (1) measurement and analysis of morphometric parameters of levees, (2) hydraulic field measurements and mathematical modeling of modern levee formation, and (3) sedimentological investigations of levee deposits, focusing on the question of what can be inferred about channel history and evolutionary patterns of levees from their deposits. The results of this project are expected to (i) permit testing of a proposed conceptual model for the development and growth of natural levees concurrently with the evolution of channels following avulsion in river floodplains, (ii) provide a clearer sense of the relative importance of diffusive and adjective mechanisms of channel-to-floodplain sediment transfer during different stages of levee development, and (iii) result in a better understanding of levee deposits and their relative importance in successions of alluvial sediments.

9903196
Slingerland

The objective of this research is to conduct a field test to better define the mechanisms of bedrock erosion occurring in streams draining the Central Range of Taiwan, and to quantify the amount of bedrock erosion as a function of stream hydraulic and sediment transport variables. In order to accomplish this goal we must measure bedload transport rates at selected field sites in the study area. Therefore a secondary goal is to apply the passive acoustic technique of Thorne and colleagues, developed under marine conditions, to measure bedload transport in these steep mountain streams. To our knowledge it is a
first attempt at this effort. The result will be a dataset of bedrock wear rates as a function of local sediment fluxes and other important variables such as intrinsic bedrock erodibility, channel hydraulics, and grain size of the material in transport. This dataset will be used to test theoretical derivations, with the ultimate goal a process-based, field calibrated fluvial bedrock incision law.

9902937
Furlong

In actively subducting plate boundaries, triple junctions migrate as a function of convergence obliquity, which is seldom orthogonal. Recent geodynamic models predict a complex crustal response to triple junction passage including initial thickening followed by thinning within a 5 m.y. time frame following passage. These geodynamic model results have specific geomorphological predictions, and geomorphological data from a region recently experiencing passage of a triple junction should provide a test of the geodynamic model. This project will gather geomorphological data along the northern California coast where the Mendocino triple junction has been migrating northward along the coast. Results will likely provide a test of the geodynamic model which should have broad applicability and also increase knowledge about the Mendocino triple junction area of northern California.

0001918
Slingerland

This grant provides partial support of the costs of upgrading computational equipment within the Geosciences Department at Penn State University (PSU). High end multi-CPU servers and networked workstations will allow sharing of computational resources by various targeted research groups, postdocs, and graduate and undergraduate students. The equipment will be used for a wide array of compute intensive research in the earth sciences including: seismological research aimed at elucidating the structure of continental crust and volcanic plumbing systems; studies of the geodynamic evolution of active plate margins; modeling of fluvial erosional processes and landscape evolution; modeling basin sedimentation processes; and simulations of chemical reactions and kinetics at mineral-water interfaces.
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ABSTRACT

Late Ordovician Epeiric Sea Circulation, Environmental Change, and Biotic Turnover: Model and Data Synthesis

One of the most difficult problems facing the earth science community today is identifying the ultimate causes of extinction and migration in the history of life. In the sedimentary record, biotic change such as extinction is often linked to evidence of environmental change, however the processes underlying environmental change are often complex and poorly understood. Numerical models of physical systems that are tested against the sedimentary record provide a means by which the ultimate causes for bioevents can be investigated. We propose to use a numerical model of ocean circulation to determine the ultimate causes for an extinction event in the Late Ordovician of North America.
This study has two main components. In the first component we hypothesize that rapid shifts in environmental conditions linked to extinction during the Late Ordovician of North America were caused by changes in bathymetry, paleogeography, and precipitation associated with mountain building. We will model ocean circulation for two time intervals that span the abrupt shift in environmental conditions and related extinction event. We will test the validity of the model results against the distribution of sedimentary indicators of oceanographic conditions.
In the second component of the study we will investigate the relative importance of single variables like changes in sea level, paleogeography, bathymetry, and precipitation in producing rapid oceanographic shifts in the epeiric seas that may have caused significant extinction of species. In investigating the ultimate causes of extinction, modeling has the advantage that single variables can be isolated and their effects on the system evaluated. We will identify plausible causes of the extinction event by determining how well the model results match the spatial and temporal faunal changes. By gaining insight into the causes of rapid oceanographic changes in these epeiric seas, this study has broad implications for understanding environmental change and extinction during any time in Earth's history when epeiric seas were important components of marine ecosystems.

0126131
Slingerland

The objective of this proposal is to design and calibrate a non-invasive, passive acoustic system for measuring spatially-integrated bedload transport rates in a natural bedrock channel. We pro-pose to measure the self-generated noise of bedload clasts in transport. Our experimental design consists of eight hydrophones and eight geophone deployed along a 100m reach, with data recorded to disk after passing through a sixteen-channel analog-to-digital conversion board on a laptop computer. The phones will be epoxied onto bedrock, near the banks, and onto large boulders in the center of the stream. The hydrophone array and the geophone array will be compared to determine which, if either, is preferable and to eliminate signals from fluid turbulence, cavitation, and bubble collapse. Both broadband and narrowband amplitudes will be analyzed for predictive power of bedload transport. The purpose of the streamwise array is to exploit the presence of downstream propagating waves of bedload transport and to determine an optimal sampling design. The system will be calibrated using bedload transport rates observed at low flows by conventional techniques such as chickenwire traps and Helley-Smith samplers, and at high flows by multiple surveys of a delta where the stream empties into a standing body of water The delta surveys will be accomplished using a shallow-water echosounder. Key hydraulic variables also will be measured in the study reach in order to relate these variables to measured bedload fluxes. The result will be a non-invasive method for measuring cross-sectionally-integrated bedload transport rates in bedrock reaches at very short time intervals.

This is a project to study the processes of sediment transport and accumulation that lead to development of the clinoforms on the Gulf of Papua (GoP) continental shelf. Shelf clinoforms are the dominant components of continental-margin stratigraphy, but little is known about the processes that create them. By combining field research (seismic profiling and piston coring) and numerical modeling, quantitative understanding of mid-shelf clinoform development at geologic time scales can be developed. These studies will test the hypothesis that the predominant mechanism for creating the present-day clinoform morphology is across-shelf gravity flow of fluid muds, whereas underlying strata may have formed in different conditions in response to changing rates of sea-level rise and sediment supply.

ABSTRACT
One of the most fundamental processes in the creation and evolution of fluvial systems is the process of channel bifurcation wherein a single channel splits into two (or more) smaller channels. Bifurcations traditionally have been grouped into two types based on whether they arise within a channel (confined), or within a standing body of water (unconfined). The former case includes braid and alluvial fan bifurcations; the latter includes deltas and crevasse splays building into bays and flooded alluvial plains. Numerous questions remain concerning the origin of both types of bifurcations: 1) What are the statistics of hydraulic geometries and water discharges for bifurcating channels? 2) Are the bifurcate channels usually equal in discharge or do they show the ratios predicted by stability theory for braid bifurcates noted above? 3) What are the statistics of angles of bifurcation in various geomorphologic settings and do they show statistically significant correlations with such basic parameters as water discharge and sediment type? 4) What factors set the angle of bifurcation in the unconfined case? 5) What factors set the longitudinal spacing of unconfined bifurcations? 6) What physical processes are responsible for the growth of the sub-aqueous levees that form the outer walls of the emerging bifurcate channels? 7) Is secondary circulation within the expanding jet a necessary condition for central bar growth as it is in braided streams? 8) What conditions are necessary to keep both arms of a bifurcation open in suspended load systems?
To answer these questions a physical- and model-based study of the bifurcation process will be conducted with the purpose of understanding the roles that three-dimensional flow velocity fields, secondary circulation, and sediment transport play in causing unconfined channel bifurcations. Although the emphasis is on the unconfined type, the ultimate fluid dynamical causes in both types may be similar. To answer the above questions the research group will: 1) conduct physical experiments in a basin with sediment feed capability suitable for studying delta deposition from sediment-water flows; 2) collect data from the literature and maps and photos on the geometries and hydraulics of both types of bifurcating channels (while emphasizing the unconfined type); 3) construct a three-dimensional, large eddy simulation (LES) model of turbulent flow and bed- and suspended-load sediment transport based on the conceptual model outlined below, and 4) use the model to conduct numerical experiments. LES results will help understand the hydrodynamics that are giving rise to the flume and field observations. Comparisons of LES results with observations will tell us whether our conceptual model for unconfined bifurcation genesis is capable of predicting the basic geometries and behaviors of unconfined channel bifurcations.

The Intellectual Merit of this Work: A better understanding and predictive capability for channel bifurcations would improve the planning and development of floodplain and channel structures, channel designs, and the success of stream restoration efforts. The contributions of this study include advancing our understanding of stream stability and channel morphology.

Broader Impacts Resulting from This Study: This work constitutes the dissertation topic and financial support for one Ph. D. candidate (already in residence). Two undergraduates will be trained in the scientific methods of morphodynamic modeling of sedimentary systems. This project will form the core of senior theses for the undergraduates. All students will benefit from exposure to a problem requiring the integration of geomorphology, sediment transport, and hydrodynamics.

This award is for one year of additional funding to complete a MARGINS Source-to-Sink investigation of the subaqueous clinoform in the Gulf of Papua (GoP). Due to fortunate circumstances they acquired more than 6800 km of high-resolution seismic data (2300 km of surface-towed Edgetech and 4500 km of hull-mounted Knudsen) and 46 piston and gravity cores for a total cumulative core length of 432 m. This third year of funding will be used to complete the analysis of the data, numerical modeling, and synthesis. Additional radiometric ages, seismic mapping of specific lenses, numerical modeling of ocean circulation at a lower sea level, and identification of sediment sources through geochemical and petrographic analysis will allow the PIs to test the hypotheses developed during the first two years of funding.
The broader impacts include the participation of graduate students and the outreach activities carried out in Papua New Guinea and the Scripps Aquarium.

EAR-0725019
Duffy
THE SUSQUEHANNA/SHALE HILLS CRITICAL ZONE OBSERVATORY
Intellectual Merit: The surface of the earth comprises a weathering engine or mill that solubilizes and disaggregates rock to form regolith. Over the long term, the rates of weathering and erosion combine to control the evolution of landscapes and help to define the access, rates of motion, and time scales of water and energy within the Critical Zone (CZ). Despite the importance of these processes, we are generally unable to quantitatively predict the rates or mechanisms by which regolith forms or how it controls water flow. Understanding these rates is of particular importance due to the rapid rates of change of the CZ in response to anthropogenic and climate perturbation. Here we propose a Critical Zone Observatory dedicated to developing this understanding for one of the most common lithologies on earth.
Our Critical Zone Observatory site, the focus of National Science Foundation-supported research since the 1970s, provides long term datasets for hydrological response that will be augmented here by new geochemical, geomorphological, ecological, and soils datasets. The observatory is a small catchment in central Pennsylvania (hereafter termed the Susquehanna/Shale Hills Observatory or SSHO) on Rose Hill Shale. As a tectonically quiescent and relatively pristine watershed, Shale Hills presents the opportunity to investigate the rates and mechanisms of regolith formation on a simple but ubiquitous bedrock lithology. The regolith at the SSHO has experienced at least two potentially significant perturbations in the geologically recent past: a climatic perturbation from peri-glacial to modern conditions and a biologic perturbation from anthropogenic clearing of forests during colonial occupation. The magnitude of these perturbations and their influence on regolith generation afford an opportunity to assess the time scales of response of soil production to both long-term climate change and human activity.
Broader Impacts: To predict the creation, evolution, and structure of regolith as a function of the geochemical, hydrologic, biologic, and geomorphologic processes in our forested landscape, we have created an interdisciplinary team of 14 scientists from 8 universities, 1 federal agency, and 2 national laboratories. This team will coordinate not only the SSHO but also six satellite sites where we will initiate similar but less extensive investigations to explore the effect of climate and composition on shale weathering. Among these, Alabama A&M and University of Puerto Rico are minority-serving institutions that will facilitate the involvement of under-represented groups in Critical Zone science. Scientists and REU students from each satellite site (eighteen students over three years) will work closely with members of the Penn State team on a variety of activities ranging from geochemical analyses of soil and bedrock samples to measurement of soil moisture with onsite detectors. The observational data and model capabilities developed in the proposed effort will be made available through web-services for both time series data and geospatial data through the CZEN cyberinfrastructure initiative. Development of the SSHO on-line information system will be supported by ongoing NSF observatory and cyberinfrastructure grants. It is our vision that the SSHO will become an exemplar for Critical Zone observational and modeling science that will attract many additional investigators from the broader community to test ideas, techniques, and predictions.

Channel bifurcations, wherein one channel splits into two, are the building blocks of braided, anastomosed, and distributary channel networks. Recent work has shown that the most common flow partitioning at bifurcations is asymmetric, and that this asymmetry seems to promote stability. Why and under what hydrographic and sedimentologic conditions this should be so, remain a puzzle. Here we propose an integrated field and theoretical investigation of the morphology, flow, and sedimentary processes of higher shear-stress, natural river bifurcations, with the objective of understanding and predicting their dynamical behavior. The field studies will be conducted to encompass two bifurcating systems with different sedimentation characteristics: i) distributary channel bifurcations of the Mossy Delta of the Saskatchewan River, where we have conducted pilot studies concerning bifurcation morphodynamics, and ii) bifurcations within the Wax Lake delta system, Louisiana, where active sedimentation is leading to rapid distributary channel growth. Several bifurcations at each site will be chosen to span a range of morphologic types. Bed morphology, water surface topography, flow velocity, and sediment transport rate will be measured at each bifurcation on a closely spaced grid at several flow stages. The field data will provide boundary and initial conditions for numerical experiments designed to define the processes and morphological conditions that lead to inherently unstable bifurcations, and detail the controlling boundary conditions for stability. Earlier numerical models will be improved by using Delft3D-FLOW, a morphodynamic model that accounts for: (1) three-dimensional turbulent unsteady, nonuniform flow, (2) interaction between bed topography, flow, and both bedload and suspended load, and (3) morphodynamically interacting erodible banks and bed. Numerical experiments will allow us to determine the feedback processes that promote stable bifurcations and predict which channel configurations are stable in the face of perturbations. We aim to yield a stability diagram for channel bifurcations and assess the influence of barform dynamics and downstream channel change in influencing bifurcation stability.
A better understanding and predictive capability of channel bifurcation behavior would improve flood forecasting, planning and development of floodplain and channel structures, channel designs, and the success of stream restoration efforts. The results of this study also will advance our knowledge of when and where river avulsions will take. Insofar as it is transformative, it will resolve the differences among competing stability theories, and produce a model, constrained by the best-available field data, which can be used to predict the stability and behavior of these ubiquitous hydrologic and geomorphic nodes.
Resulting from This Study: This work constitutes the dissertation topic and financial support for one Ph. D. candidate and will support one post-doctoral researcher. Two Native American high school students from the Cumberland House Cree Nation, Saskatchewan will be trained in its scientific methods. All students will benefit from exposure to a problem requiring the integration of geomorphology, sediment transport, hydrodynamics, and morphodynamic modeling.

0841901
Kirby

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

This grant supports acquisition of ground penetrating radar (GPR) equipment, a real-time kinematic GPS system, 3-D visualization software and field hardened notebook computers. The equipment will support research and research training in the Department of Geosciences at Penn State University that will benefit from the capability of GPR to image the near subsurface. Specific equipment to be purchased includes a GPR system with multiple borehole antennas (at frequencies of 50, 100 and 200 MHz) to support stratigraphic, tectonic and hydrologic studies and a high frequency pulsed GPR system to be deployed for imaging the thickness, internal structure and basal contacts of glaciers. The equipment will support a range of PI and student research including studies of the dynamics of rivers of ice draining the West Antarctic Ice Sheet, studies of the movement of solutes through ground water systems, morphodynamic investigations of meandering and braided river systems, studies of pedogenesis and hill slope processes, and paleoseismological investigations of buried faults near active plate margins. In particular, research use of the GPR systems for study of the response of polar continental ice sheets to climate change is of profound and timely societal interest. GPR, in conjunction with seismic reflection techniques, offers the means to image glacial structure at high resolution to hundreds of meters and to probe the structure and nature of underlying deposits that serve to lubricate or slow glacial advance toward the sea. Students trained in GPR operation, data analysis and interpretation are well poised to gain employment in a host of civil engineering and environmental consulting fields that increasingly rely on GPR as a tool for near subsurface imaging.

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

This project investigates exceptionally species-rich but poorly known fossil plant deposits in Patagonia, Argentina, dating from 66-47 million years old. Approximately 80% of more than 500 species so far collected are new to science, and the time interval includes the end-Cretaceous (K-T) "dinosaur" extinction and recovery as well as important global warming and cooling events. This critical time period is otherwise only well known, for land plants, in Western North America. The fossil floras hold immense relevance to modern biodiversity as an unrivaled data source regarding plant evolution, distribution, and ecology in the Southern Hemisphere. Some of the fundamental questions to be addressed are: 1) was there a major K-T plant extinction and long recovery in Patagonia, as in North America? 2) what are the modern distributions of the fossil plants? Australasian plants, representing a lost land connection via Antarctica, are the best known, but was the area also a source for today's Neotropical forests? and 3) was ancient Patagonia a rainforest?

This is a well-developed international collaboration involving abundant intellectual exchange. Training and career advancement of graduate students and postdocs is a major focus, as well as public education. Broad scientific benefits include: 1) the first densely sampled South American floral and paleoclimatic record for a time interval of immense global interest; 2) numerous, novel, well-dated plant-lineage appearances in South America of great interest for plant evolution and biogeography; 3) the first robust geological understanding of the floras; and 4) a high potential for significant unplanned discoveries. Research results will be disseminated widely. The thousands of fossil specimens will be permanently available through deposition in a well-curated public institution, Museo Paleontológico Egidio Feruglio, Trelew, Argentina.

The various shapes of river deltas were thought to be dependent mainly upon downstream processes, such as the wave- and tidal-power of the ocean basin and the energy flux of the river, but recent work has suggested that upstream controls, such as load and sediment type (i.e. cohesive vs. noncohesive sediment) may also be a major factor controlling delta morphology. The PIs propose a theoretical and field study of how sediment load and type,and thus source terrain, control a delta?s planform morphology and internal stratigraphy. A series of numerical experiments using Delft3D, a morphodynamic physics-based model simulating 3D fluid flow and sediment transport, will extend the parameter space of earlier work by varying sediment fluxes and grain size distributions of a parent river subject to one flood wave per year.
A final set of experiments will include the effects of wave and tides. The numerical predictions will be compared to cores, serial aerial photography, bathymetry, and ground penetrating radar datasets from modern deltas representing end-members of the modeling results. Candidate deltas include Wax Lake and Mossy deltas of Louisiana and Saskatchewan, and El Coyote fan delta on the western coast of the Gulf of California, where already existing data will be supplemented by limited fieldwork, Pleistocene shelf-edge deltas such as off Apalachicola, FL, and ancient deltas such as the Cretaceous Ferron and Panther Tongue deltas of Utah. A better understanding and predictive capability of delta planform and stratigraphy could improve our ability to predict coastline evolution in the face of changes in sediment feed volume and type and changes in the rate of creation of accommodation space due to global and local sea level rise.

Broader Impacts Resulting from This Study: The lead PI?s involvement with the National Center for Earth-surface Dynamics will ensure that this work will contribute to the science needed to restore the Mississippi delta and reverse the trend of land loss. This work will also be the dissertation topic and financial support for two graduate students and theses for two undergraduate students. All students will benefit from exposure to a problem requiring the integration of geomorphology, sediment transport, hydrodynamics, and morphodynamic modeling.