P Jonathan Patchett - US grants

The northern part of the North American Cordillera comprises a mosaic of tectonic fragments, some of which formed in intra- oceanic environments far from North America. Other fragments appear to have accumulated in a continental margin environment. Present information about terranes in northern British Columbia and adjacent Yukon indicates that the Nisling terrane was originally formed in proximity to a continent, and is now surrounded by fragments of oceanic affinity. Prior work has out- lined relations that permit several different tectonic scenarios. This renewal will attempt, by mapping, structure and strati- graphic studies and isotopic analysis, to resolve between these possible scenarios. Results are expected to place significantly tighter constraints on the rate and processes of continental assembly in the northern cordillera.

9315625 Patchett This project will measure Nd isotopes, REE and other trace elements in sandstone from the miogeocline of the Canadian Rocky Mountains in order to quantify the amount of continental material supplied during the lifetime of the Canadian Cordillera. Detrital zircon data will also be used to determine the relative amounts of far-traveled versus near-travelled detritus. The results will give a useful baseline for future provenance studies in the region. Results will also have implications for the existence of a large, 340 Ma terrane in the region and the movement of individual terranes within the orogen. These findings will have broad application to the study of tectonic terranes in other orogenic belts.

9527009 Barton This collaborative project (NSF and industry) will yield a novel comparison of igneous-related mineralization across regions of contrasting characteristics. It provides an integrated approach to sorting our some of the major controls on igneous-related metallogenesis. These studies build on earlier NSF-sponsored research by the PIs. Industry funding/collaboration is in place for student and field support; NSF funds will be used primarily for geochemical, petrological, and geochronometric studies. Comparative studies will be conducted in three regions which have contrasting crustal compositions, igneous and tectonic histories, and metallogenic characteristics. These contrasts, when considered together, will provide tests of hypotheses that can not be evaluated in any local area. Overall, the PIs will develop the following topics: (1) characteristics of key districts, (2) magmatic compositional controls on mineralization, (3) crustal-scale controls on magmatism and metallogeny, and (4) secular variations reflecting preservation, exposure, and contrasting petrogenetic regimes. The goal of the coupled geochemical and field studies is to better understand the geology, geochemistry, and timing of representative magmatic-hydrothermal centers.

9976676
Ruiz

This award provides partial funding for the acquisition of a multicollector inductively-coupled plasma mass spectrometer (MC-ICP-MS) to be installed and operated by the Department of Geological Sciences at the University of Arizona. The University of Arizona is committed to providing the remaining funds necessary for the acquisition. Research applications at the University of Arizona requiring the capabilities of the MC-ICP-MS include (1) Origin of metal deposits at convergent plate margins from Os and Pb isotope analysis, (2) Life in extreme environments from Fe, Cu, and Zn isotopes, (3) Origin of silicic magma chambers from in situ Sr analysis of feldspars, (4) History of crust and mantle evolution using Hf isotopes, (5) Geochronology of convergent plate margins using in-situ U-Pb in zircons, and (6) U-Th dating of carbonate soils and calibration of the C-14 time scale by U-Th dating of speleothems and corals.

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