Monazite is a light rare earth element (LREE)-bearing phosphate mineral that present in wide variety of rock types, has an extremely variable composition reflecting host conditions, and robust geochronometer can preserve crystallization ages through long history geological events. crystals typically contain distinct compositional domains represent successive generations monazite, which turn, provide detailed record the geologic its rocks. The electron microprobe be used to characterize...

Research Article| November 01, 1999 Age mapping and dating of monazite on the electron microprobe: Deconvoluting multistage tectonic histories Michael L. Williams; Williams 1Department Geosciences, University Massachusetts, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar J. Jercinovic; Jercinovic P. Terry Author Article Information Publisher: Geological Society America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology...

The experimental alteration of monazite to allanite, REE-epidote, fluorapatite, and/or fluorapatitebritholite was investigated at 450 610 MPa and 500 °C. Experiments involved + albite ± K-feldspar muscovite biotite SiO2 CaF2 variety fluids including H2O, (KCl H2O), (NaCl (CaCl2 (Na2Si2O5 1 M HCl, 2 NaOH, KOH, Ca(OH)2, (CaCO3 H2O). reaction products, or lack thereof, clearly show that the stability relations between monazite, allanite REE-epidote are more dependent on fluid composition ratio...

The field of metamorphic petrology has seen spectacular advances in the past decade, including new X‐ray mapping techniques for characterizing rocks and minerals, internally consistent thermobarometers, software constructing viewing phase diagrams, methods to date processes, perhaps most significant, revised petrologic databases ability calculate accurate diagrams pseudosections. These tools provide power resolution constraining pressure‐temperature (P‐T) histories tectonic events. Two books...

Abstract Monazite is a common accessory phase in felsic granulite ribbon mylonites exposed the Upper Deck domain of Athabasca terrane, western Canadian Shield. Field relationships, bulk rock geochemistry and equilibria modelling Na 2 O–CaO–K O–FeO–MgO–Al O 3 –SiO –H O–TiO –Fe system are consistent with garnet‐rich rocks representing residual products ultrahigh temperature melting biotite‐bearing paragneisses driven by intraplating mafic magma continental lower crust. The c . 2.64–2.61 Ga...

The term petrochronology has increasingly appeared in publications and presentations over the past decade. been defined a somewhat narrow sense as “the interpretation of isotopic dates light complementary elemental or information from same mineral(s)” (Kylander-Clark et al. 2013). Although elementary are certainly central critical part most, if not all, studies, range recent studies that might use covers much broader scope. “petrochronology” alternatively be detailed incorporation...

Abstract When searching for an object in a cluttered scene, we can use our memory of the target features to guide search, and responses neurons multiple cortical visual areas are enhanced when their receptive field contains stimulus sharing features. Here tested role ventral prearcuate region (VPA) prefrontal cortex control feature attention area V4. VPA was unilaterally inactivated monkeys performing free-viewing search array stimuli, impairing monkeys’ ability find affected hemifield, but...

Abstract The upper deck of the East Athabasca mylonite triangle (EAmt), northern Saskatchewan, Canada, contains mafic granulites that have undergone high P–T metamorphism at conditions ranging from 1.3 to 1.9 GPa, 890–960 °C. Coronitic textures in these indicate a near‐isothermal decompression path 0.9 800 Godfrey granite occurs north adjacent domain. Well‐preserved corona constrain igneous crystallization and early intermediate‐pressure granulite field (Opx + Pl) 1.0 775 °C followed by...

Research Article| January 01, 2009 Age, provenance, and tectonic setting of Paleoproterozoic quartzite successions in the southwestern United States James V. Jones, III; III 1Department Geological Sciences, Jackson School Geosciences, University Texas at Austin, 78712, USA †Present address: Department Earth Arkansas Little Rock, 72204, USA; e-mail: jvjones@ualr.edu Search for other works by this author on: GSW Google Scholar N. Connelly; Connelly Karl E. Karlstrom; Karlstrom 2Department...

Trace element micro-analysis has evolved steadily since the early days of EPMA, yet remains an extraordinarily challenging subject. The enhanced capabilities modern instrumentation, including use spectrometers with high X-ray collection efficiencies, brightness electron sources, and improved stability all contribute to our ability improve detection limits analytical spatial resolution. Along much software for data acquisition analysis, recent progress in EPMA made trace realm more accessible...

Abstract Interpreting tectonic histories from metamorphic tectonites requires an understanding of the linkages and feedbacks between deformation metamorphism. Relationships metamorphism can be divided into two broad groups: active passive. Active relationships involve direct interactions whereby directly influences reactions or affects rate style deformation. One most important ‘active’ is role that plays in helping to remove unstable reactant phases promote growth stable product phases....

Research Article| August 01, 2001 Electron-microprobe monazite dating of ca. 1.71–1.63 Ga and 1.45–1.38 deformation in the Homestake shear zone, Colorado: Origin early evolution a persistent intracontinental tectonic zone Colin A. Shaw; Shaw 1Department Earth Planetary Sciences, University New Mexico, Albuquerque, Mexico 87131, USA Search for other works by this author on: GSW Google Scholar Karl E. Karlstrom; Karlstrom Michael L. Williams; Williams 2Department Geosciences, Massachusetts,...

Research Article| September 01, 1996 U-Pb geochronologic constraints on the Paleoproterozoic crustal evolution of Upper Granite Gorge, Grand Canyon, Arizona David P. Hawkins; Hawkins 1Department Earth, Atmospheric and Planetary Sciences, Massachusetts Institute Technology, Cambridge, 02139 Search for other works by this author on: GSW Google Scholar Samuel A. Bowring; Bowring Bradley R. Ilg; Ilg 2Department Earth University New Mexico, Albuquerque, Mexico 87131 Karl E. Karlstrom; Karlstrom...

The geophysically defined Snowbird tectonic zone is manifested in northernmost Saskatchewan as a deep-crustal, multistage mylonitic structure, the East Athabasca mylonite triangle. triangle, located at northeastern apex of stiff, crustal-scale "lozenge," composed mid-Archean annealed mylonites and late Archean ribbon mylonites, formed during two granulite facies events (850–1000 °C, 1.0 GPa). flow pattern geometrically kinematically complex, corresponds to that expected adjacent stiff...

Research Article| May 01, 2005 Reconstruction of a large deep-crustal terrane: Implications for the Snowbird tectonic zone and early growth Laurentia K.H. Mahan; Mahan 1Department Geosciences, University Massachusetts, Amherst, Massachusetts 01003, USA Search other works by this author on: GSW Google Scholar M.L. Williams Author Article Information Publisher: Geological Society America Received: 11 Oct 2004 Revision 22 Dec Accepted: 23 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print...