Ordovician eclogites from the Chinese Beishan: implications for the tectonic evolution of the southern Altaids | |
Qu, JF (Qu, J. F.)7; Xiao, WJ (Xiao, W. J.); Windley, BF (Windley, B. F.); Han, CM (Han, C. M.); Mao, QG (Mao, Q. G.); Ao, SJ (Ao, S. J.); Zhang, JE (Zhang, J. E.) | |
刊名 | JOURNAL OF METAMORPHIC GEOLOGY
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2011 | |
卷号 | 29期号:8页码:803-820 |
关键词 | Altaids Beishan orogen eclogite Ordovician P-T path |
ISSN号 | 0263-4929 |
英文摘要 | Numerous lenses of eclogite occur in a belt of augen orthogneisses in the Gubaoquan area in the southern Beishan orogen, an eastern extension of the Tianshan orogen. With detailed petrological data and phase relations, modelled in the system NCFMASHTO with THERMOCALC, a quantitative P-T path was estimated and defined a clockwise P-T path that showed a near isothermal decompression from eclogite facies (> 15.5 kbar, 700-800 (degrees)C, omphacite + garnet) to high-pressure granulite facies (12-14 kbar, 700-750 degrees C, clinopyroxene + sodic plagioclase symplectitic intergrowths around omphacite), low-pressure granulite facies (8-9.5 kbar, similar to 700 degrees C, orthopyroxene + clinopyroxene + plagioclase symplectites and coronas surrounding garnet) and amphibolite facies (5-7 kbar, 600-700 degrees C, hornblende + plagioclase symplectites). The major and trace elements and Sm-Nd isotopic data suggest that most of the Beishan eclogite samples had a protolith of oceanic crust with geochemical characteristics of an enriched or normal mid-ocean ridge basalt. The U-Pb dating of the Beishan eclogites indicates an Ordovician age of c. 467 Ma for the eclogite facies metamorphism. An (39)Ar/(40)Ar age of c. 430 Ma for biotite from the augen gneiss corresponds to the time of retrograde metamorphism. The combined data from geological setting, bulk composition, clockwise P-T path and geochronology support a model in which the Beishan eclogites started as oceanic crust in the Palaeoasian Ocean, which was subducted to eclogite depths in the Ordovician and exhumed in the Silurian. The eclogite-bearing gneiss belt marks the position of a high-pressure Ordovician suture zone, and the calculated clockwise P-T path defines the progression from subduction to exhumation. |
学科主题 | 变质岩岩石学 |
WOS关键词 | MINERAL EQUILIBRIA CALCULATIONS ; UHP METAMORPHIC BELT ; ASIAN OROGENIC BELT ; HIGH-PRESSURE ROCKS ; NW CHINA ; U-PB ; SYSTEM K2O-FEO-MGO-AL2O3-SIO2-H2O-TIO2-FE2O3 ; PALEOZOIC ACCRETIONARY ; COLLISIONAL TECTONICS ; RETROGRADED ECLOGITES |
WOS研究方向 | Geology |
语种 | 英语 |
出版者 | WILEY-BLACKWELL |
WOS记录号 | WOS:000294872200001 |
内容类型 | 期刊论文 |
源URL | [http://119.78.100.197/handle/2HKVOGP0/39353] ![]() |
专题 | 中国地质调查局 |
作者单位 | 1.[Qu, J. F.] Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China [Qu, J. F. 2.Xiao, W. J. 3.Han, C. M. 4.Mao, Q. G. 5.Ao, S. J. 6.Zhang, J. E.] Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China [Windley, B. F.] Univ Leicester, Dept Geol, Leicester LE1 7RH, Leics, England 7.中国地质科学院地质研究所 |
推荐引用方式 GB/T 7714 | Qu, JF ,Xiao, WJ ,Windley, BF ,et al. Ordovician eclogites from the Chinese Beishan: implications for the tectonic evolution of the southern Altaids[J]. JOURNAL OF METAMORPHIC GEOLOGY,2011,29(8):803-820. |
APA | Qu, JF .,Xiao, WJ .,Windley, BF .,Han, CM .,Mao, QG .,...&Zhang, JE .(2011).Ordovician eclogites from the Chinese Beishan: implications for the tectonic evolution of the southern Altaids.JOURNAL OF METAMORPHIC GEOLOGY,29(8),803-820. |
MLA | Qu, JF ,et al."Ordovician eclogites from the Chinese Beishan: implications for the tectonic evolution of the southern Altaids".JOURNAL OF METAMORPHIC GEOLOGY 29.8(2011):803-820. |
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