Download or read book Investigations of Monazite and Garnet Chronology and Applications to the Archean Gneiss Terrane of the Wind River Range Wyoming written by Charles Peirce DeWolf and published by . This book was released on 1993 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1994 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Canadian Journal of Earth Sciences written by and published by . This book was released on 2006 with total page 710 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Late Archean Metamorphic History of the Wind River Range Wyoming written by Casey L. Donohue and published by . This book was released on 2002 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Geologic Occurrence of Monazite written by William Courtney Overstreet and published by . This book was released on 1967 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review of the distribution of monazite and of the geologic controls affecting the amount of thorium in monazite.
Download or read book Petrogenesis of Two Contrasting Late Archean Granitoids Wind River Range Wyoming written by and published by . This book was released on 1989 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Petrogenesis of Two Contrasting Late Archean Granitoids Wind River Range Wyoming written by John S.. Stuckless and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Development and Use of Monazite and Garnet Geochronology with Application to Tectonic Processes written by Emily Margaret Peterman and published by . This book was released on 2009 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding tectonic processes in 4-D remains a fundamental target of earth scientists. This research investigates two geochronometers--garnet and monazite--and their application to tectonic processes. First, garnet geochronology determines the timing of mineral growth during the subduction and exhumation of the Western Gneiss Region, a giant ultrahigh-pressure terrane in Norway. Coupled with geochemical modeling, these data describe the major phase transformations and densification reactions that ultimately affect the amount of continental crust that subducts to high- and ultrahigh-pressures. Second, because monazite is a common accessory mineral in a broad range of compositions, it has been used extensively to date the timing of metamorphic events. The second portion of this paper presents methods that were developed to accurately date monazite with chemical abrasion (CA) thermal ionization mass spectrometry (TIMS), a high-precision geochronologic technique. Thirdly, recent advances in microbeam technologies have made the acquisition of geochronologic data far more accessible, but the methods have not been rigorously tested. The final portion of this research systematically examines two of the most common microbeam techniques--laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and secondary ion mass spectrometry (SIMS). The data suggest that the accuracy and precision of microbeam techniques are only adequate for research questions where an error of +/-10% is acceptable.
Download or read book Monazite in the Granitic Rocks of the Southeastern Atlantic States written by John Beaver Mertie and published by . This book was released on 1979 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Petrogenetic of Two Constrating Late Archean Granitoids Wind River Range Wyoming written by John S. Stuckless and published by . This book was released on 1989 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolution of the Paleo and Mesoarchean Gneiss of the Central Wyoming Province in the Western Grantite Mountains of Wyoming written by J. Fred McLaughlin and published by . This book was released on 2016 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation contains three parts that investigate the geological evolution of Paleo- and Mesoarchean gneiss and other metamorphic rocks in the central Wyoming Province. These rocks are exposed in the Sacawee block, an area of deformed Archean crust within the core of the Granite Mountains, Wyoming. The first chapter presents a review of the Sacawee block, including new research completed during this dissertation. Different orthogneiss suites extend across the Sacawee block, and U-Pb geochronology identifies two gneiss suites: a group of layered tonalitic gneisses and intercalated mafic rocks that are 3385-3450 Ma, and massive, trondhjemite and granite gneisses that are 3300-3330 Ma. Some gneisses contain inherited zircon grains that were 3.82 Ga. Hf isotopic compositions of 3.82 Ga zircon are negative, suggesting an older protolith. The orthogneisses of the Sacawee block formed by remelting of Hadean crust, which makes this one of the few terranes in the world with inheritance that old. A suite of quartz-cordierite gneiss (QCG) are described as distinct to the Sacawee block. They are Mg-rich and Ca- and Na-poor, which distinguishes them from regional metasedimentary and orthogneiss suites. Three categories of QCG were recognized; one type retains sedimentary textures, while a second group retains textural evidence of orthogneiss parentage. A third group of QCG has uncertain parentage and relationship to surrounding gneiss. The QCG formed via Mg-rich metasomatic alteration, which could be associated with Neoarchean tectonism and the assembly of the Southern accreted terranes or an older rifting event. A Neoarchean supracrustal sequence, the Radio Tower Hill paragneiss, is located in the southwestern Sacawee block. This sequence is ~2.66 Ga, which is younger than other regional metasediments. It has detrital zircon grains sourced from the older rocks of the Wyoming Province, as well as Neoarchean detrital zircon grains. The sediment was deposited in a basin near an intercontinental arc within the Wyoming Province and approaching terranes from the south. The structural geology of the western Granite Mountains preserves a record of deformation associated with the convergence of Southern accreted terranes and the older parts of the Wyoming Province. In the field area, foliation trends northeast-southwest and dips to the south. Shear zones follow foliation trends and are subvertical. The study area is shown to contain two structural domains; a block of pure shear called the Radio Tower Hill domain, and a block of simple shear called the Tin Cup Mountain domain. These domains were formed along a transpressional belt between the obliquely converging Southern accreted terranes and the northern Wyoming Province. U-Pb ages of a leucosome in the field area and a deformed leucogranite in the central Granite Mountains are coeval at ~2635 Ma, interpreted to define the time of peak deformation during accretion. The northeast-southwest Archean fabrics appear to have influenced the orientation of younger structures in the central and southeastern Wyoming Province.
Download or read book U Pb Geochronology of Monazite and Zircon in Precambrian Metamorphic Rocks from the Ruby Range SW Montana written by Carson L. Jones and published by . This book was released on 2008 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: U-Pb accessory minerals in metamorphic rocks from the Ruby Range, southwestern Montana, were analyzed isotopically and chemically by microprobe techniques in order to constrain the timing of Precambrian thermotectonic events that affected the NW edge of the Wyoming craton. Dated samples represent the Cherry Creek Metasupracrustal Suite and associated pegmatites (CCMS, youngest), the Dillon quartzofeldspathic gneiss (DQG), and the Pre-Cherry Creek basement gneisses (PCCG, oldest). Undeformed bodies of pegmatite cross-cut the NE-trending fabric of the CCMS, and coexisting monazite and xenotime from the pegmatite yield crystallization ages of 1762 " 6 Ma and 1754 " 6 Ma, respectively (207Pb/206Pb upper-intercept ages reported at 95% confidence). These results constrain latest magmatism to within a ~1760 Ma time frame, while also establishing this as a minimum age for the cross-cut fabric. Metamorphic monazite in CCMS metapelites formed at 1814 " 15 and 1773 " 8 Ma, whereas monazites preserved as inclusions in CCMS garnet record a much older ~2450 Ma event (total-Pb ages reported at 95% confidence). In DQG samples that also contain ~2450 Ma monazite in garnet, matrix monazite preserves mixed ~1760-1580 Ma dates. In one DQG sample, polymetamorphic matrix monazite formed at 1784 " 57 and 2468 " 11 Ma, whereas older magmatic zircon formed at 2772 " 11 Ma. Polygenetic zircon in another DQG sample formed at both 2471 " 20 Ma (metamorphic; Th/U = 0.0-0.1) and at 2772 " 7 Ma (magmatic; Th/U = 0.5-0.7). Likewise, zircon in two PCCG samples preserves mostly 2437 " 47 and 2762 " 37 Ma ages in rims and cores, respectively, but also exhibits subordinate, inherited cores of ~3000-3500 Ma age. Indications of a ~2550-2500 Ma event in the Ruby Range are represented by a single total-Pb date of monazite (inclusion in DQG garnet) and by a population of PCCG metamorphic zircon dated at 2523 " 14 Ma (upper-intercept age). The mixed ~1760-1580 Ma dates observed for monazite in one DQG migmatite are of uncertain origin. Possible hypotheses include rifting related to the development of the Belt Basin or to younger break-up and dispersal of supercontinent Rodinia. The ~1760 Ma mineral ages date the waning phases of thermotectonism associated with the Wyoming-Medicine collision along the Great Falls tectonic zone, which spanned an ~1865-1760 Ma interval. Monazite growth ages of ~1815-1770 Ma document earlier stages of this collision. The ~2460 Ma mineral ages reflect an earlier, cryptic thermotectonic event that is temporally associated with incipient breakup of the ~2700-2500 Ma supercontinent Kenorland. The ~2550 Ma ages may record the juxtaposition of the Montana metasedimentary terrane as part of the Wyoming craton, along the NE-trending Madison mylonite zone, during terminal assembly of Kenorland. Finally, occurrences of ~2780 Ma mineral ages in the DQG record the Beartooth orogenic signature, whereas preservation of ~3000-3500 Ma zircon ages documents a Pre-Beartooth history for the PCCG basement.
Download or read book Rubidium strontium and Samarium neodymium Geochronology of a Late Archean Granite Central Wind River Mountains Wyoming written by Deborah K. Grisham and published by . This book was released on 1987 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Monazite Placer at the Junction of the North Tyger River with the Middle Tyger River Spartanburg County South Carolina written by Leland A. Hansen and published by . This book was released on 1955 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Sm Nd in Garnet and U Pb in Zircon Geochronology to Constrain the Age of Peak Metamorphism in the Northeastern Pamir written by Michael Kenneth Stevens and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The age of peak metamorphism of garnet bearing ortho-gneisses and schists in the Kongur Shan and Muztaghata gneiss domes of northeastern Pamir exposed is uncertain due to discrepancies in the recorded peak metamorphic age between different geochronometers from previous geochronologic studies. U-Pb analysis of detrital zircon record a predominately Jurassic metamorphic signature in the Muztaghata gneiss dome, while Th-Pb dating of monazite inclusions in garnet yield an Oligo-Miocene metamorphic signature in both the Kongur Shan and Muztaghata massifs. These results leave the question of when the peak metamorphic assemblages observed in these gneiss domes formed. To address the conflicting ages and resolve the timing of peak metamorphism in the northeastern Pamir; the timing of garnet growth related to the peak metamorphic assemblages was determined using the Sm-Nd isotope system and further investigated using U-Pb analyses of Zircon. Garnet whole-rock Sm-Nd geochronology from both the Kongur Shan and Muztaghata gneiss domes yields late Cenozoic ages, confirming that the late Miocene age recorded by the monazite is related to peak metamorphism. Laser ablation U-Pb analyses of zircon yield Carboniferous to Triassic crystallization ages along with numerous partially reset grains with ages through the late Mesozoic and early Cenozoic. In addition, a single grain with a distinct recrystallized rim yielded an age of 8.61±0.41 Ma. The analyses performed in this study, in combination with the previous monazite and detrital zircon data, provide a clear late Miocene age for peak prograde metamorphism in the gneiss domes of the northeastern Pamir. This age is interpreted to be related to under-thrusting and crustal thickening in the Pamir. My results also suggest that Th-Pb dating of monazite can be a more reliable geochronometer for addressing the timing of peak metamorphism in poly-metamorphic terranes.
Download or read book The Maidens Gneiss Goochland Terrane Virginia written by Catherine Shirvell and published by . This book was released on 2004 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geochronology of an Archean Granite Owl Creek Mountains Wyoming written by C. E. Hedge and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
