TY - JOUR T1 - Microprobe monazite geochronology; new refinements and new tectonic applications JF - Abstracts with Programs - Geological Society of America Y1 - 2003 A1 - Williams, Michael L. A1 - Jercinovic, Michael J. A1 - Mahan, Kevin A1 - Joseph P Kopera KW - #StaffPubs KW - age; KW - electron probe data; KW - geochronology; KW - Geochronology; 03 KW - Igneous and metamorphic petrology; 05A KW - metamorphic rocks; KW - metamorphism; KW - methods; KW - monazite; KW - P-T-t paths; KW - phosphates; AB -

High-resolution compositional mapping and dating of monazite on the electron microprobe is a powerful addition to microstructural and petrologic analysis and an important tool for tectonic studies. Its in-situ nature and high spatial resolution offer an entirely new level of structurally and texturally specific geochronologic data that can be used to put absolute time constraints on P-T-D paths, constrain the rates of sedimentary, metamorphic, and deformational processes, and provide new links between metamorphism and deformation. New analytical techniques have significantly improved the precision and accuracy of the technique and new mapping and image analysis techniques have increased the efficiency and strengthened the correlation with fabrics and textures. Microprobe geochronology is particularly applicable to three persistent microstructural-microtextural problem areas: (1) constraining the chronology of metamorphic assemblages; (2) constraining the timing of deformational fabrics; and (3) interpreting other geochronological results. In addition, authigenic monazite can be used to date sedimentary basins, and detrital monazite can fingerprint sedimentary source areas, both critical for tectonic analysis. Although some monazite generations can be directly tied to metamorphism or deformation, at present, the most common constraints rely on monazite inclusion relations in porphyroblasts that, in turn, can be tied to the deformation and/or metamorphic history. Microprobe mapping and dating allow geochronology to be incorporated into the routine microstructural analytical process, resulting in a new level of integration of time (t) into P-T-D histories. The Legs Lake exhumational shear zone in Saskatchewan is a classic example. Monazite can be tied to decompressional metamorphic reactions in the upper plate and to prograde reactions and shear fabrics in the footwall, firmly constraining the timing of regional exhumations with a long multiphase tectonic history.

PB - Geological Society of America (GSA) : Boulder, CO, United States CY - United States VL - 35 SN - 00167592 UR - http://silk.library.umass.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=geh&AN=2004-076942&site=ehost-live&scope=site IS - 33 N1 - Accession Number: 2004-076942; Conference Name: Geological Society of America, Northeastern Section, 38th annual meeting; Halifax, NS, Canada; Conference Date: 20030327; Language: English; Coden: GAAPBC; Collation: 2; Collation: 22-23; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 200422; Monograph Title: Geological Society of America, Northeastern Section, 38th annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic JO - Abstracts with Programs - Geological Society of America ER -