Acquisition of (U-Th)/He Thermochronology Laboratory

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9902988MillerThis grant provides partial support for the costs of constructing a new (U-Th)/He thermochronology laboratory to compliment existing 40Ar/39Ar and fission track (FT) thermochronology laboratories at Stanford University. The term thermochronology refers to the use of natural radioactive decay "clocks" to reconstruct the time-temperature histories experienced by rocks. Because temperature can commonly be used as a proxy for burial depth, these methods may be used to help reconstruct exhumation, mountain building, and deformational histories. Different thermochronometers are sensitive within different temperature intervals and thus at different depths. In the mineral apatite, the He and FT system are highly complementary in that their sensitivity intervals are about 40 to 85 degrees C (about 1.5 to 3 km depth) and 80-125 degrees C (about 3 to 5 km depth), respectively.Initial work in the new facility will be directed toward a range of studies including: investigating late Cenozoic transpression and mountain building along the San Andreas fault system in the San Francisco Bay Area to contribute toward kinematic understanding of the system and to seismic hazard assessment; reconstructing the history of Tertiary extension in the northern Basin and Range Province in Nevada and Utah; reconstructing Mesozoic and Cenozoic mountain building and deformational histories in central Asia; and using fission track external detector uranium micromapping methods and SHRIMP-RG ion microprobe element micromapping methods to assess the effects of U and Th zoning on the accuracy of (U-Th)/He ages.***