Argon Transport in Chain and Sheet Silicates:  A Combined   Laser Microprobe and TEM
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Chain and sheet silicates are important minerals in metamorphic                 rocks because of their common occurence and their usefulness in                 isotopic dating.  Most radiometric mineral dates record the times               which the minerals cooled through their blocking temperatures for               isotopic diffusion and these differ for the various isotopes and                the various chain and sheet silicates.  Geologists exploit this                 variability to delineate the "temperature versus time" histories                of metamorphic terranes.  The calculated blocking temperatures                  for many minerals, however, such as for argon in hornblende and                 micas, is poorly constrained unless one assumes a diffusion                     geometry reflecting the anisotropy of these silicate lattices,                  and a diffusion dimension (or radius) reflecting their                          microtextural homogeneity.  By measuring the argon spatial                      distribution in both natural and hydrothermally treated samples                 of hornblende, biotite, and muscovite with the laser microprobe,                it is planned to estimate these properties.  These estimates will               be further tested by observing microtextures of the minerals with               the transmission electron microscope (TEM).  Results from the                   controlled heating experiments will also facilitate                             interpretation of the spatial information being derived from                    40Ar/39Ar laser microprobes.
{'FirstName': 'Tullis', 'LastName': 'Onstott', 'PI_MID_INIT': 'C', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Tullis C Onstott', 'EmailAddress': 'tullis@princeton.edu', 'NSF_ID': '000426578', 'StartDate': '05/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Princeton University', 'CityName': 'PRINCETON', 'ZipCode': '085442001', 'PhoneNumber': '6092583090', 'StreetAddress': '1 NASSAU HALL', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'New Jersey', 'StateCode': 'NJ', 'CONGRESSDISTRICT': '12', 'CONGRESS_DISTRICT_ORG': 'NJ12', 'ORG_UEI_NUM': 'NJ1YPQXQG7U5', 'ORG_LGL_BUS_NAME': 'THE TRUSTEES OF PRINCETON UNIVERSITY', 'ORG_PRNT_UEI_NUM': None}
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{'Code': '1573', 'Text': 'Petrology and Geochemistry'}
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