SHRIMP U-Pb zircon dating from eclogite lens in marble, Shuanghe area,;Dabie UHP terrane: restriction on the prograde, UHP and retrograde;metamorphic ages.

	SHRIMP U-Pb zircon dating from eclogite lens in marble, Shuanghe area,;Dabie UHP terrane: restriction on the prograde, UHP and retrograde;metamorphic ages.
	Liu Fulai 3; Xue HuaiMin ; Xu ZhiQin ; Liang FengHua ; Gerdes, Axel
刊名	ACTA PETROLOGICA SINICA
	2006
卷号	22 期号:7 页码:1761-1778
关键词	eclogite lens in marble mineral inclusion laser Raman CL image SHRIMP U-Pb dating Dabie UHP terrane zoned zircon
ISSN号	1000-0569
英文摘要	Laser Raman spectroscopy and cathodoluminescence ( CL) images show that zircons separated from eclogite lens in impure marble from Shuanghe area, Dabie UHP metamorphic belt, are characterized by inherited ( detrital), prograde, UHP and retrograde metamorphic overgrowth domains. The inherited ( detrital) zircons contain PI + Ap and Qtz + PI in the white-luminescent core and the dark-luminescent rim, respectively. Whereas the prograde metamorphic domains ( with grey-luminescent CL images) preserve quartz eclogite-facies mineral assemblage of Qtz + Grt + Omp + Phe + Dol + Ap, formed at 588 similar to 668 degrees C and 1.7 similar to 1.8 GPa. In contrast, the UHP metamorphic domains ( with white-luminescent CL images) retain index UHP mineral assemblage of Coe + Grt + Omp + Arg + Mgs + Ap, and record UHP condition of T = 784 similar to 849 degrees C and P > 5. 5GPa. The outmost retrograde rims ( with dark-luminescent CL images) however, contain no-UHP minerals such as quartz and calcite, related to the regional amphibolite-facies retrogression with T = 550 similar to 720 degrees C and P = 0. 8 similar to 1. 4GPa. SHRIMP U-Pb dating on these zoned zircons identify four discrete and meaningful age groups: 2701 similar to 1753Ma (Pb-207/Pb-206 age) is recorded in the inherited ( detrital) zircons derived from Archean-Proterozoic protolith, the prograde metamorphism of quartz eclogite-facies in the prograde domains occurred at 249 similar to 241 Ma (Pb-206/ U-238 age), the UHP metamorphic event in the UHP mineral-bearing domains was at 239 similar to 231 Ma (Pb-206/U-238 age), and the late amphibolite-facies retrograde overprint in the outmost rims was restricted at 219 similar to 211 Ma (Pb-206/U-238 age). Thus, Archean-Proterozoic continental materials of the Dabie UHP terrane were subducted to 55 similar to 60km depth at Early Triassic and occurred quartz eclogite facies metamorphism simultaneously. Then these quartz eclogite-facies metamorphic rocks continued subduction to 165 similar to 175 km deep mantle depth at Middle Triassic and experienced UHP metamorphism; The peak pressures are based on the equilibrium calculation of the reaction dolomite = magnesite + aragonite. This UHP metamorphism recorded a lower geotherm step of 4.7 degrees C km(-1) which is within what was previously considered a 'forbidden' condition within earth. Finally these UHP metamorphic rocks were exhumed to mid-crustal levels ( about 30km) in the Late Triassic and overprinted regional amphibolite facies metamorphism. The subduction and exhumation rate deduced from the SHRIMP data and metamorphic P-T conditions is 11 similar to 12km Myr(-1) and 7. 5 - 8. 1km Myr(-1), respectively. Fast subduction and rapid exhumation has been considered to be one of the most important factors for the preservation of prograde, UHP and retrograde metamorphic minerals in zircons. Such a fast exhumation suggests that the Dabie UHP metamorphic rocks returned towards the crustal depths as dominant part of a buoyant sliver, caused as a consequence of slab breakoff.
学科主题	地质年代学
WOS关键词	EAST-CENTRAL CHINA ; ULTRAHIGH-PRESSURE METAMORPHISM ; SOUTHWESTERN SULU ; TERRANE ; ARAGONITE PLUS MAGNESITE ; COESITE-BEARING ZIRCON ; MINERAL ; INCLUSIONS ; JIANGSU-PROVINCE ; NORTHEASTERN JIANGSU ; QINGLONGSHAN OXYGEN ; CONTINENTAL-CRUST
WOS研究方向	Geology
语种	中文
出版者	SCIENCE CHINA PRESS
WOS记录号	WOS:000245957000002
内容类型	期刊论文
源URL	[http://119.78.100.197/handle/2HKVOGP0/38263]
专题	中国地质科学院地质研究所
作者单位	1.Chinese Acad Geol Sci, Inst Geol, Key Lab Continental Dynam, Beijing 100037, Peoples R China. 2.Univ Frankfurt, Inst Mineral, D-60054 Frankfurt, Germany. 3.中国地质科学院地质研究所
推荐引用方式 GB/T 7714	Liu Fulai,Xue HuaiMin,Xu ZhiQin,et al. SHRIMP U-Pb zircon dating from eclogite lens in marble, Shuanghe area,;Dabie UHP terrane: restriction on the prograde, UHP and retrograde;metamorphic ages.[J]. ACTA PETROLOGICA SINICA,2006,22(7):1761-1778.
APA	Liu Fulai,Xue HuaiMin,Xu ZhiQin,Liang FengHua,&Gerdes, Axel.(2006).SHRIMP U-Pb zircon dating from eclogite lens in marble, Shuanghe area,;Dabie UHP terrane: restriction on the prograde, UHP and retrograde;metamorphic ages..ACTA PETROLOGICA SINICA,22(7),1761-1778.
MLA	Liu Fulai,et al."SHRIMP U-Pb zircon dating from eclogite lens in marble, Shuanghe area,;Dabie UHP terrane: restriction on the prograde, UHP and retrograde;metamorphic ages.".ACTA PETROLOGICA SINICA 22.7(2006):1761-1778.