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Mineral Ages and P-...
Mineral Ages and P-T Conditions of Late Paleozoic High-Pressure Eclogite and Provenance of M Lange Sediments from Atbashi in the South Tianshan Orogen of Kyrgyzstan
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Hegner, E. (author)
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Klemd, R. (author)
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Kroener, A. (author)
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Corsini, M. (author)
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Alexeiev, D. V. (author)
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Iaccheri, L. M. (author)
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- Zack, Thomas, 1968 (author)
- Gothenburg University,Göteborgs universitet,Institutionen för geovetenskaper,Department of Earth Sciences
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Dulski, P. (author)
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Xia, X. (author)
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Windley, B. F. (author)
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(creator_code:org_t)
- 2010
- 2010
- English.
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In: American Journal of Science. - 0002-9599. ; 310:9, s. 916-950
- Related links:
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https://gup.ub.gu.se...
Abstract
Subject headings
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- Ages derived from various isotope systems in high-pressure (HP) rocks of the western Tianshan orogen of NW China have been interpreted as evidence for late Carboniferous and/or Triassic collision of the accretionary margin of the Central Asian Orogenic Belt (CAOB) with the Tarim Craton. In order to elucidate this controversy, we present new P-T data as well as Sm-Nd and (40)Ar/(39)Ar cooling ages for an eclogite sample from Atbashi in the accretionary m lange of the South Tianshan suture in Kyrgyzstan, some 500 km along strike to the west of the controversial locality in the upper Akeyazhi River Valley in NW China. A clockwise P-T path for the eclogite with peak pressures of 18 to 24 kbar at 520 to 600 degrees C is consistent with near-isothermal decompression and exhumation in a subduction zone before collision of the CAOB with the Tarim Craton. Geochemical data and an initial epsilon Nd value of similar to +9 suggest an N-MORB protolith for the eclogite. The high-pressure mineral assemblage of the eclogite yielded a statistically robust Sm-Nd isochron age of 319 +/- 4 Ma (2 sigma, 5 data points, MSWD = 0.4) for equilibration and closure of the Sm-Nd system during HP metamorphism. (40)Ar/(39)Ar dating of phengite from the same sample yielded a cooling age of 316 +/- 3 Ma (2 sigma) implying rapid exhumation. Docking of the Tarim Craton with the southern margin of the Middle Tianshan-North Tianshan blocks in Kyrgyzstan during the late Carboniferous is supported by widespread emplacement of A-type granitoids of early Permian age that suggest a setting of consolidated crust. An tuunetamorphosed and little deformed molasse-type conglomerate of latest Carboniferous age, overlying the HP rocks, indicates that HP metamorphism, exhumation, and exposure of the HP m lange occurred from 320 to 300 Ma. The detrital zircon age spectrum of a metagraywacke sample from the accretionary melange suggests sources in the Tarim Craton and/or from the Middle and North Tianshan that possibly comprise rifted blocks from Tarim.
Subject headings
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geokemi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geochemistry (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geology (hsv//eng)
- NATURVETENSKAP -- Geovetenskap och miljövetenskap (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences (hsv//eng)
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- ref (subject category)
- art (subject category)
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- By the author/editor
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Hegner, E.
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Klemd, R.
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Kroener, A.
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Corsini, M.
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Alexeiev, D. V.
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Iaccheri, L. M.
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show more...
-
Zack, Thomas, 19 ...
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Dulski, P.
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Xia, X.
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Windley, B. F.
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show less...
- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
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and Geochemistry
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
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and Geology
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Earth and Relate ...
- Articles in the publication
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American Journal ...
- By the university
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University of Gothenburg