SHRIMP U-Pb zircon dating of the Wulian Complex: defining the boundary between the North and South China Cratons in the Sulu Orogenic Belt, China
SHRIMP U-Pb zircon dating of the Wulian Complex: defining the boundary between the North and South China Cratons in the Sulu Orogenic Belt, China
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DOI：
10.1016/j.precamres.2007.10.008
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发表时间：
2008-05
影响因子：
3.8
通讯作者：
Jian‐Bo Zhou;S. Wilde;Guochun Zhao;Xingzhou Zhang;Changqing Zheng;W. Jin;Hongjiang Cheng
中科院分区：
文献类型：
--
作者：
Jian‐Bo Zhou;S. Wilde;Guochun Zhao;Xingzhou Zhang;Changqing Zheng;W. Jin;Hongjiang Cheng
在苏鲁超高压带北方边缘，毗邻五莲-烟台断裂带，五莲群新元古代变质沉积岩和变质火山岩与片麻状花岗岩共生，统称五莲杂岩。五莲群变质沉积岩中碎屑锆石SHRIMP U-Pb年龄为3478 ~ 625 Ma。根据锆石不整合度<10%，可大致分为4个群体：> 3000 Ma，最大年龄为3339 Ma; 2700- 2400 Ma，峰值年龄为2436 Ma; 2200- 1800 Ma，峰值年龄为2156 Ma; 770 Ma。这些结果表明五莲群的沉积时代在距今770 Ma以后，一些碎屑物质很可能来自华南地区的新元古代源区。变质火山岩SHRIMP锆石U-Pb定年结果表明，变质火山岩的206 Pb/238 U加权平均年龄为761± 8 Ma，与华南地区其他岩石一致，并与Rodinia超大陆裂解过程中的同裂谷岩浆活动有关。五莲群与五莲杂岩的新元古代花岗岩一起，控制了华北和华南两大板块之间的三叠纪缝合带的位置。根据我们的新资料，该缝合线应位于五莲杂岩的北部，并以百尺河-烟台断裂为标志。
Neoproterozoic metasedimentary and metavolcanic rocks of the Wulian Group are associated with gneissic granitoids at the northern margin of the Sulu UHP Belt, adjacent to the Wulian–Yantai Fault, and are collectively referred to as the Wulian complex. SHRIMP U–Pb dating of detrital zircon from the metasedimentary rocks of the Wulian Group indicates a range in age from 3478 to 625Ma. Based on zircons <10% discordant, they can be broadly divided into four populations: >3000Ma, with the oldest age being 3339Ma; 2700–2400Ma, with a peak at 2436Ma; 2200–1800Ma, with a peak at ∼2156Ma; and at ∼770Ma. These results indicate that deposition of the Wulian Group was after ∼770Ma and that some detrital material most likely came from Neoproterozoic sources in the South China Craton (SCC). SHRIMP U–Pb zircon dating of a metavolcanic rock defines a weighted mean206Pb/238U age of 761±8Ma, which is consistent with other rocks of South China affinity and can be correlated with syn-rift magmatism during the breakup of the supercontinent Rodinia. The Wulian Group, together with Neoproterozoic granites of the Wulian complex, constrains the location of the Triassic suture zone between the North China and South China Cratons. Based on our new data, the suture must lie north of the Wulian complex and is marked by the Baichihe–Yantai Fault.