Publications
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A geological synthesis of the Precambrian shield in Madagascar
Available U–Pb geochronology of the Precambrian shield of Madagascar is summarized and integrated into a synthesis of the region’s geological history. The shield is described in terms of six geodynamic domains, from northeast to southwest, the Bemarivo, Antongil–Masora, Antananarivo, Ikalamavony, Androyan–Anosyan, and Vohibory domains. Each domain is defined by distinctive suites of metaigneous ro
Authors
Robert D. Tucker, J.Y. Roig, B. Moine, C. Delor, S. G. Peters
Diatom evidence for the onset of Pliocene cooling from AND-1B, McMurdo Sound, Antarctica
The late Pliocene, ~ 3.3–3.0 Ma, is the most recent interval of sustained global warmth in the geologic past. This window is the focus of climate reconstruction efforts by the U.S. Geological Survey's Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) Data/Model Cooperative, and may provide a useful climate analog for the coming century. Reconstructions of past surface ocean condition
Authors
Christina Riesselman, R. B. Dunbar
An evaluation of automated GIS tools for delineating karst sinkholes and closed depressions from 1-meter LIDAR-derived digital elevation data
LiDAR (Light Detection and Ranging) surveys of karst terrains provide high-resolution digital elevation models (DEMs) that are particularly useful for mapping sinkholes. In this study, we used automated processing tools within ArcGIS (v. 10.0) operating on a 1.0 m resolution LiDAR DEM in order to delineate sinkholes and closed depressions in the Boyce 7.5 minute quadrangle located in the northern
Authors
Daniel H. Doctor, John A. Young
The Cambrian-Ordovician rocks of Sonora, Mexico, and southern Arizona, southwestern margin of North America (Laurentia)
Cambrian and Ordovician shelf, platform, and basin rocks are present in Sonora, Mexico, and southern Arizona and were deposited on the southwestern continental margin of North America (Laurentia). Cambrian and Ordovician rocks in Sonora, Mexico, are mostly exposed in scattered outcrops in the northern half of the state. Their discontinuous nature results from extensive Quaternary and Tertiary surf
Authors
William R. Page, Alta C. Harris, John E. Repetski
100,000-year-long terrestrial record of millennial-scale linkage between eastern North American mid-latitude paleovegetation shifts and Greenland ice-core oxygen isotope trends
We document frequent, rapid, strong, millennial-scale paleovegetation shifts throughout the late Pleistocene, within a 100,000+ yr interval (~ 115–15 ka) of terrestrial sediments from the mid-Atlantic Region (MAR) of North America. High-resolution analyses of fossil pollen from one core locality revealed a continuously shifting sequence of thermally dependent forest assemblages, ranging between tw
Authors
Ronald J. Litwin, Joseph P. Smoot, Milan J. Pavich, Helaine W. Markewich, George Brook, Nancy J. Durika
40Ar/39Ar evidence for Late Devonian deformation in the Chester shear zone, east central Maine
No abstract available.
Authors
Hind Ghanem, Michael J. Kunk, Allan Ludman, David Bish, Robert Wintsch, Joseph Biasi
On the identification of a Pliocene time slice for data–model comparison
The characteristics of the mid-Pliocene warm period (mPWP: 3.264–3.025 Ma BP) have been examined using geological proxies and climate models. While there is agreement between models and data, details of regional climate differ. Uncertainties in prescribed forcings and in proxy data limit the utility of the interval to understand the dynamics of a warmer than present climate or evaluate models. Thi
Authors
Alan M. Haywood, Aisling M. Dolan, Steven J. Pickering, Harry J. Dowsett, Erin L. McClymont, Caroline L. Prescott, Ulrich Salzmann, Daniel J. Hill, Stephen J. Hunter, Daniel J. Lunt, James O. Pope, Paul J. Valdes
The PRISM (Pliocene Palaeoclimate) reconstruction: Time for a paradigm shift
Global palaeoclimate reconstructions have been invaluable to our understanding of the causes and effects of climate change, but single-temperature representations of the oceanic mixed layer for data–model comparisons are outdated, and the time for a paradigm shift in marine palaeoclimate reconstruction is overdue. The new paradigm in marine palaeoclimate reconstruction stems the loss of valuable c
Authors
Harry J. Dowsett, Marci M. Robinson, Danielle K. Stoll, Kevin M. Foley, Andrew L. A. Johnson, Mark Williams, Christina Riesselman
Proterozoic to Cenozoic geology above, within and beneath the Blue Ridge Composite Thrust Sheet as exposed along the Blue Ridge Parkway in the Peaks of Otter region, central Virginia Blue Ridge: Guidebook for the 43rd Annual Virginia Geological Field Con
No abstract available.
Authors
Mark W. Carter, C. Scott Southworth, John N. Aleinikoff
Unraveling Alleghanian orogenesis in southern Connecticut: The history of the Lyme Dome
No abstract available.
Authors
Gregory J. Walsh, John N. Aleinikoff, Robert P. Wintsch
Characterizing post-drainage succession in Thermokarst Lake Basins on the Seward Peninsula, Alaska with TerraSAR-X Backscatter and Landsat-based NDVI data
Drained thermokarst lake basins accumulate significant amounts of soil organic carbon in the form of peat, which is of interest to understanding carbon cycling and climate change feedbacks associated with thermokarst in the Arctic. Remote sensing is a tool useful for understanding temporal and spatial dynamics of drained basins. In this study, we tested the application of high-resolution X-band Sy
Authors
Prajna Regmi, Guido Grosse, Miriam C. Jones, Benjamin M. Jones, Katey Walter Anthony
Summary of the diamond resource potential and production capacity assessment of Guinea
In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the Ge
Authors
Peter G. Chirico, Katherine C. Malpeli