Abstract 51452: EARLY PROTEROZOIC 208PB/232TH IN SITU ION PROBE DATING OF MONAZITE FROM ARCHEAN METAMORPHIC SUITES, TOBACCO ROOT MOUNTAINS, MT
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51452: EARLY PROTEROZOIC 208PB/232TH IN SITU IO... file:///Users/jbrady/JBB_Documents/JBB/Abstracts/GSA,%201999%20-... 1 of 2 3/5/08 7:41 AM 1999 GSA Annual Meeting -Denver, Colorado
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A Late Miocene-Pliocene origin for the Central Himalayan inverted metamorphism
Perhaps the best known occurrence of an inverted metamorphic sequence is that found immediately beneath the Himalayan Main Central Thrust (MCT), generally thought to have been active during the Early Miocene. However, in situ 208Pb/ 232Th dating of monazite inclusions in garnet indicates that peak metamorphic recrystallization of the MCT footwall occurred in this portion of the central Himalaya...
متن کاملComparative isotopic and chemical geochronometry of monazite, with implications for U-Th-Pb dating by electron microprobe: An example from metamorphic rocks of the eastern Wyoming Craton (U.S.A.)
Polygenetic monazite grains in diverse Precambrian crystalline rocks from the Black Hills, South Dakota, have been analyzed in situ by ion and electron microprobe methods (SHRIMP and EMP), to evaluate the accuracy and precision of EMP ages determined using a new analytical protocol that incorporates improved background acquisition and interference corrections. Parallel evaluations were conducte...
متن کاملDating of Precambrian Metasedimentary Rocks and Timing of their Metamorphism in the Soursat Metamorphic Complex (NW IRAN): Using LA–ICP-MS, U–Pb Dating of Zircon and Monazite
Soursat Metamorphic Complex (SMC) in west of Takab city is one of the polyphase metamorphic terrenes in northern Sanandaj-Sirjan metamorphic belt of Iran. The SMC composed mainly of metasedimentary rocks associated with granitic intrusions. Based on metamorphic rocks, two metamorphic phases could be separate in the complex. M1 is representative of regional metamorphisms which varies from greens...
متن کاملAbstract 50828: EVIDENCE FOR A MAJOR, EARLY PROTEROZOIC OROGENIC EVENT IN THE TOBACCO ROOT MOUNTAINS OF SOUTHWESTERN MONTANA
50828: EVIDENCE FOR A MAJOR, EARLY PROTEROZO... file:///Users/jbrady/JBB_Documents/JBB/Abstracts/GSA,%201999%20-... 1 of 2 3/5/08 7:39 AM 1999 GSA Annual Meeting -Denver, Colorado
متن کاملProterozoic metamorphism and cooling in the southern Lake Superior region, North America and its bearing on crustal evolution
Metamorphism along the southern margin of the Archean Superior Province has been historically attributed to the Penokean orogeny. A narrow corridor of amphibolite facies rocks north of the main suture does record 1.83–1.80 Ga metamorphic monazite U–Th–Pb ages that mark the culmination of arc accretion. However, subsequent widespread amphibolite facies metamorphism and associated magmatism is re...
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