@article {309,
	title = {Microprobe monazite geochronology; new refinements and new tectonic applications},
	journal = {Abstracts with Programs - Geological Society of America},
	volume = {35},
	year = {2003},
	note = {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},
	month = {2003/03/01/},
	pages = {22 - 23},
	publisher = {Geological Society of America (GSA) : Boulder, CO, United States},
	address = {United States},
	abstract = {<p>
	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.</p>
},
	keywords = {$\#$StaffPubs, age;, electron probe data;, geochronology;, Geochronology; 03, Igneous and metamorphic petrology; 05A, metamorphic rocks;, metamorphism;, methods;, monazite;, P-T-t paths;, phosphates;},
	isbn = {00167592},
	url = {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},
	author = {Williams, Michael L. and Jercinovic, Michael J. and Mahan, Kevin and Joseph P Kopera}
}
@article {310,
	title = {Monazite geochronology of Proterozoic quartzites; a powerful tool for understanding reactivation of continental lithosphere in the Southwestern United States},
	journal = {Abstracts with Programs - Geological Society of America},
	volume = {34},
	year = {2002},
	note = {Accession Number: 2004-069830; Conference Name: Geological Society of America, Northeastern Section, 37th annual meeting; Springfield, MA, United States; Conference Date: 20020325; Language: English; Coden: GAAPBC; Collation: 1; Collation: 26; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 200421; Monograph Title: Geological Society of America, Northeastern Section, 37th annual meeting; Monograph Author(s): Anonymous; Reviewed Item: Analytic},
	month = {2002/03/01/},
	pages = {26 - 26},
	publisher = {Geological Society of America (GSA) : Boulder, CO, United States},
	address = {United States},
	abstract = {<p>
	The influence of approximately 1.65 vs. 1.4 Ga tectonism on the evolution of the Proterozoic orogenic belt in the southwestern United States has been an issue of considerable debate. This belt was assembled at approximately 1.75-1.65 Ga, but recent work has highlighted a significant reactivation of the orogen at 1.4 Ga. The discovery of abundant monazite in regionally extensive, 1-2 km thick quartzites found throughout the orogenic belt may provide important new constraints on its tectonic history. These quartzites define the present regional geometry of exposed Proterozoic rocks and are believed to strongly influence local structure. Preliminary results of in-situ microprobe dating of monazite from the Ortega Quartzite in the Tusas Mountains in northern New Mexico suggest an increasing influence of 1.4 Ga tectonism from north to south within the range. Monazite from the Jawbone Syncline within northernmost part of the range consistently yields ages of 1.75 to 1.72 Ga. These monazite grains are interpreted to be mostly detrital in origin, with REE and age zoning reflecting the history of the source terranes. Monazite from an anticline immediately to the south has 1.72-1.75 Ga detrital cores with 1.67-1.68 Ga rims, implying that initial fold formation occurred during the approximately 1.67-1.65 Ga Mazatzal Orogeny. Monazite from the middle and southern Tusas Mountains is predominantly 1.4 Ga in age. This suggests that a previously documented gradient in deformation and metamorphism from north to south may reflect a multistage tectonic history for the range, with an increasingly intense overprint of 1.4 Ga tectonism to the south. Monazite has also been found in several Proterozoic quartzites in Colorado, allowing the possibility to compare and correlate deformation and metamorphism across the region. Monazite dating in thick quartzites represents a powerful tool by which the effects of approximately 1.65 and 1.4 Ga tectonism can be separated, leading to a better understanding of the evolution and stabilization of Proterozoic crust in the southwestern United States and may be an important new technique in deconvoluting the tectonic histories of other orogenic belts.</p>
},
	keywords = {$\#$StaffPubs, absolute age;, continental lithosphere;, crust;, deformation;, Geochronology; 03, Jawbone Syncline;, lithosphere;, Mazatzal Orogeny;, metamorphic rocks;, metamorphism;, monazite;, New Mexico;, orogeny;, Paleoproterozoic;, phosphates;, Precambrian;, Proterozoic;, quartzites;, Southwestern U.S.;, tectonics;, Tusas Mountains;, United States;, upper Precambrian;},
	isbn = {00167592},
	url = {http://silk.library.umass.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true\&db=geh\&AN=2004-069830\&site=ehost-live\&scope=site},
	author = {Joseph P Kopera and Williams, Michael L. and Jercinovic, Michael J.}
}
@article {312,
	title = {Monazite geochronology of the Proterozoic Ortega Quartzite; documenting the extent of 1.4 Ga tectonism in the Tusas Range and beyond},
	journal = {New Mexico Geology},
	volume = {24},
	year = {2002},
	note = {Accession Number: 2004-009303; Conference Name: New Mexico Geological Society spring meeting; Socorro, NM, United States; Conference Date: 20020405; Language: English; Coden: NMGED2; Collation: 1; Collation: 59; Publication Types: Abstract Only; Serial; Conference document; Updated Code: 200403; Monograph Title: New Mexico Geological Society spring meeting; abstracts; Monograph Author(s): Anonymous; Reviewed Item: Analytic},
	month = {2002/05/01/},
	pages = {59 - 59},
	publisher = {New Mexico Bureau of Mines and Mineral Resources : Socorro, NM, United States},
	address = {United States},
	keywords = {$\#$StaffPubs, absolute age;, dates;, deformation;, electron probe data;, geochronology;, Geochronology; 03, ion probe data;, mass spectra;, metamorphic rocks;, metamorphism;, monazite;, New Mexico;, orogeny;, Ortega Group;, phosphates;, Precambrian;, Proterozoic;, quartzites;, spectra;, Structural geology; 16, tectonics;, Tusas Mountains;, United States;, upper Precambrian;},
	isbn = {0196948X},
	url = {http://silk.library.umass.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true\&db=geh\&AN=2004-009303\&site=ehost-live\&scope=site},
	author = {Joseph P Kopera and Williams, Michael L. and Jercinovic, Michael J.}
}
