U-Pb zircon geochronology and creochemistry of Neoproterozoic volcanic   rocks in the Tarim Block of northwest China: implications for the   breakup of Rodinia supercontinent and Neoproterozoic glaciations

doi:10.1016/j.precamres.2004.09.007

CORC > 北京大学 > 地球与空间科学学院

	U-Pb zircon geochronology and creochemistry of Neoproterozoic volcanic rocks in the Tarim Block of northwest China: implications for the breakup of Rodinia supercontinent and Neoproterozoic glaciations
	Xu, B ; Jian, P ; Zheng, HF ; Zou, HB ; Zhang, LF ; Liu, DY
刊名	precambrian research
	2005
关键词	SHRIMP data bimodal volcanism Neoproterozoic Tarim Block Rodinia glaciation ND ISOTOPIC EVIDENCE SOUTH CHINA YANGTZE CRATON MARINOAN GLACIATION CONTINENTAL-CRUST WESTERN-AUSTRALIA SNOWBALL EARTH MANTLE PLUME SR ISOTOPES ICE AGES
DOI	10.1016/j.precamres.2004.09.007
英文摘要	As the lowest volcanics-bearing unit of the Neoproterozoic succession, the Beiyixi Formation is the key to understanding the early response to the breakup of the Roninia supercontinent in the Tarim Block. The SHRIMP analyses of zircons from die volcanic rocks at the bottom of the Beiyixi Formation yield. a weighted mean Pb-206/U-238 age of 155 +/- 15 Ma. This is interpreted as the eruption age of the Beiyixi volcanic rocks. The Beiyixi volcanic rocks consist of bimodal basalt and dacite-rhyolite with a SiO2 gap between 55% and 65%. The mafic rocks display negative epsilon(Nd) (755 Ma) values (-9.9 to -10.8). moderate enrichment in LILE and variable depletion in Nb, Ta and P, resembling those of the tholeiitic basalts in continental rift. Geochemical and Nd isotopic characteristics suggest that the mafic rocks were derived from partial melting of an enriched lithospheric mantle reservoir. The felsic rocks show negative epsilon(Nd) (755 Ma) values (-7.9 to -9.2), negative Nb, Ta, P and Ti anomalies, very high La-N/Yb-N (62-92) ratios and LILE abundances, and may be generated by melting of eclogites or garnet amphibolites in the lower crust, as a result of basalt emplacement into continental crust during continental rifting. The age of 755 +/- 15 Ma indicates that the Beiyixi glaciation took place later than 755 Ma and it could be correlated with the Chang'an glaciation in the Yangtze Block and the Sturtian-Rapitan glaciation in other Rodinia Blocks. The geochemical characteristics of the Beiyixi volcanic rocks resemble those of the rift-related magmatism in other Rodinia Blocks. suggesting that the Beiyixi volcanism was a part of global mamatism during the breakup of Rodinia supercontinent. The age and geochemical features of the Beiyixi volcanic rocks also reveal that the mantle plume activity spread to the northwestern margin of the Rodinia supercontinent and probably resulted in the breakup between Australia and Tarim Blocks. (C) 2004 Elsevier B.V. All rights reserved.; Geosciences, Multidisciplinary; SCI(E); 125; ARTICLE; 2; 107-123; 136
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/156072]
专题	地球与空间科学学院
推荐引用方式 GB/T 7714	Xu, B,Jian, P,Zheng, HF,et al. U-Pb zircon geochronology and creochemistry of Neoproterozoic volcanic rocks in the Tarim Block of northwest China: implications for the breakup of Rodinia supercontinent and Neoproterozoic glaciations[J]. precambrian research,2005.
APA	Xu, B,Jian, P,Zheng, HF,Zou, HB,Zhang, LF,&Liu, DY.(2005).U-Pb zircon geochronology and creochemistry of Neoproterozoic volcanic rocks in the Tarim Block of northwest China: implications for the breakup of Rodinia supercontinent and Neoproterozoic glaciations.precambrian research.
MLA	Xu, B,et al."U-Pb zircon geochronology and creochemistry of Neoproterozoic volcanic rocks in the Tarim Block of northwest China: implications for the breakup of Rodinia supercontinent and Neoproterozoic glaciations".precambrian research (2005).