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SHRIMP U-Pb zircon geochronology and its implications on the Xilin Gol Complex，Inner Mongolia,China [查看] SHIGuanghai、LIUDunyi、ZHANGFuqin、JIANPing、MIAOLaicheng、SHIYuruo、

Abstract The Xilin Gol Complex, consisting of deformed and metamorphosed rocks, was exposed as a large geological unit within the Central Asian Orogenic Belt, but its forming and subsequent deformed and metamorphic time has been an issue of little consensus. Petrographic analyses and SHRIMP dating on biotite-plagioclase gneiss, one of the major rocks within the Xilin Gol Complex, in southeast Xilinhot City, Inner Mongolia, China, where the Xilin Gol Complex was identified and named, yield its lower limit age of 437 ± 3 Ma (2s ) by its magmatic zircon SHRIMP U-Pb dating, and an upper limit age of 316 ± 3Ma (2s ), which was constrained by SHRIMP dating of magmatic zircons from adjacent undeformed garnet-bearing granite which intruded the Complex.The Complex was thus determined to be formed and subsequently deformed/metamorphosed from the late Ordovician-early Silurian to the mid-Carboniferous. Consequently, it is not the Precambrian terrane as previously considered by most geologists. More or less, the major rock —— biotiteplagioclase gneiss within the Complex is more likely to be Paleozoic fore-arc turbidite formation before metamorphism and intensive deformation, in which the detrital zircons gave sporadic Precambrian ages as old as up to 3.1 Ga. The source of the turbidite formation is multiple, which may be derived either from the North China Craton, or from the South-Mongolia Micro-continent, or probably came from a potential and undiscovered in situ terranes aged 600—800 Ma or even up to ca 3.1 Ga near the Complex.

Opening of the Tethys in southwest China and its significance to the breakup of East Gondwanalang in late PaleozoicEvidence from SHRIMP U-Pb zircon analyses for the Garze ophiolite block [查看] YANQuanren、WANGZongqi、LIUShuwen、LIQiugen、ZHANGHongyuan、WANGTao、LIUDunyi、SHIYuruo、JIANPing、WANGJianguo、ZHANGDehui、ZHAOJian

Abstract SHRIMP U-Pb zircon analyses for a gabbro sample from the Garzê ophiolite block yielded a mean 206Pb/238U age of 292±4 Ma, which indicated that the spreading time of the Garzê-Litang Tethys was most likely at the earliest Permian. Combined with previous studies, we suggest that the opening of the Tethys in southwest China was derived from breakup of the East Gondwanaland in the late Paleozoic.

Zircon SHRIMP U-Pb dating for gabbro at Chaotiehe in the Haicheng area- eastern Liaoning [查看] MIAOLaiCheng、ZHANGFuQin、LIUDunYi、SHIYuRuo、XIEHangQiang

Chaotiehe gabbroic intrusion in the eastern part of Liaoning Province was dated by the zircon SHRIMP U-Pb technique. The results gave an emplacement age of 126±4 Ma, indicating that the intrusion thus formed during the lithospheric thinning of the North China Craton (NCC) in the Early Cretaceous rather than in a rifting setting during the Paleoproterozoic as previously thought. The gabbroic intrusion contains abundant old zircons with Paleoproterozoic (2.10–2.46 Ga and ca. 1.87 Ga) and Neoproterozoic(747–969 Ma) ages. The Paleoproterozoic zircons were probably derived from NCC itself, whereas the Neoproterozoic ones were likely from materials of the Yangtze Craton that had previously been subducted beneath NCC. These geochronological dates are of important implications for understanding the Mesozoic crustal evolution of NCC.

Late Jurassic-Early Cretaceous Plutonism in the Northern Part of the Precambrian North China Craton： SHRIMP Zircon U-Pb Dating of Diorites and Granites from the Yunmengshan Geopark, Beijing [查看] SHIYuruo、ZHAOXitao、MAYinsheng、HUDaogong、LIUQisheng、WUZhenhan、ZHAOYuanyi、LIUDunyi

Abstract：The Yunmengshan Geopark in northern Beijing is located within the Yanshan range．It contains the Yunm engshan batholith．which is dominated by two plutons：the Yunmengshan gneissic granite and the Shicheng gneissic diorite．Four samples of the Yunmengshan gneissic granite give SHRIMP zircon U—Pb ages from 145 to 141 Ma。whereas four samples of the Shicheng gneissic diorite have ages from 159 Ma to 151 M a．Dikes that cut the Yunmengshan diorite record SHRIMP zircon U-Pb are of 162±2 and 156+4 Ma．The cumulative plots of zircons from the diorites show a peak age of 155 Ma．without inherited zircon cores．and the peak age of 142 Ma for granite is interpreted as the emplacement age of the Yunm engshan granitic pluton，whose igneous zircons contain inherited zircon cores．The data presented here show that there were two pulses of m agm atism ：early diorites。followed c13 Ma later by true granites．which incorporated material from an older continental crust．

SHRIMP Zircon U-Pb Dating of Gabbro and Granite from the Huashan Ophiolite,Qinling Orogenic Belt,China Neoproterozoic Suture on the Northern Margin of the Yangtze Craton [查看] SHIYuruo、LIUDunyi、ZHANGZongqing、MIAOLaicheng、ZHANGFuqin、XUEHongmei

Abstract: The recently identified Huashan ophiolitic melange was considered as the eastern part of the Mianliie suture in the Qinling orogenic belt. SHRIMP zircon U-Pb geochronology on gabbro from the Huashan ophiolite and granite intruding basic volcanic rocks indicates crystallization ages of 947±14 Ma and 876±17 Ma respectively. These ages do not support a recently proposed Hercynian Huashan Ocean, but rather favor that a Neoproterozoic suture assemblage (ophiolite) is incorporated into the younger (Phanerozoic) Qinling orogenic belt.

Detrital Zircon of 4100 Ma in Quartzite in Burang,Tibet [查看] DUOJi、WENChunqi、FANXiaoping、GUOJianci1、NIZhiyao、LIXiaowen、SHIYuruoandWENQuan

A detrital zircon aged 4.1 Ga is discovered by the SHRIMP U-Pb method in a quartzite in Burang County, western Tibet. This is presently the oldest single-grain detrit al zircon in China. The Th-U ratios of the two testing points of the >4.0 Ga zircon are between 0.76 and 0.86, indicating their magmatic origin. This discovery ha s offered an important age for inve stigating the geological evolution of the Qinghai-Tibet Plateau.