文档共享_Beijing SHRIMP Center

你好,请

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 [查看] Jian-BoZhou、SimonA.Wilde、Guo-ChunZhao、Xing-ZhouZhang、Chang-QingZheng、WeiJin、HongCheng

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 mean 206Pb/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 betwwen the North China and South China Cratons,Based on our new data,the suturemust lie north of the Wulian complex and is marked by the Baichihe-Yantai Fault.

SHRIMP U–Pb zircon dating of the Neoproterozoic Penglai Group and Archean gneisses from the Jiaobei Terrane,North China, and their tectonic implications [查看] Jian-BoZhou、SimonA.Wilde、Guo-ChunZhao、Chang-QingZheng、WeiJin、Xing-ZhouZhang、HongCheng

Archean basement gneisses and supracrustal rocks, together with Neoproterozoic (Sinian) metasedimentary rocks (the Penglai Group) occur in the Jiaobei Terrane at the southeastern margin of the North China Craton. SHRIMP U–Pb zircon dating of an Archean TTG gneiss gave an age of 2541±5 Ma, whereas metasedimentary rocks from the Neoproterozoic Penglai Group yielded a range in zircon ages from 2.9 to 1.8 Ga.The zircons can be broadly divided into three age populations, at: 2.0–1.8 Ga, 2.45–2.1 Ga and >2.5 Ga. Detrital zircon grains with ages >2.6 Ga are few in number and there are none with ages <1.8 Ga. These results indicate that most of the detrital material comes from a Paleoproterozoic source, most likely from the Jianshan and Fenzishan groups, with some material coming from Archean gneisses in the Jiaobei Terrane. An age of 1866±4Ma for amphibolite-facies hornblende–plagioclase gneiss, forming part of a supracrustal sequence within the Archean TTG gneiss, indicates Late Paleoproterozoic metamorphism. Both the Archean gneiss complex and Penglai metasedimentary rocks resemble previously described components of the Jiao-Liao-Ji orogenic belt and suggest that the Jiaobei Terrane has a North China Craton affinity; they also suggest that the time of collision along the Jiao-Liao-Ji Belt was at ∼1865 Ma.

© BJSHRIMP 2013 - bjshrimp.cn