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    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．
    Report on 3.4 Ga SHRIMP Zircon Age from the Yuntaishan Geopark in Jiaozuo, Henan Province [查看] GAOLinzhi、ZHAOTing、WANYusheng、ZHAOXun、MAYinsheng、YANGShouzheng
    Using the reported new U-Pb age with the Sensitive High-Resolution Ion hlicroprobe (SHRIRIP-II), zircon U-Pb ages were obtained from two samples of K-feldspar felsic paragneiss and K-feldspar gneissoid trondhjemite on the southern margin of the Taihang hlountains in the North China Craton. The protolith of the K-feldspar felsic paragneiss is argillaceous-sandy clastic sedimentary rock, probably deposited in the Neoarchean. Most of the detritus zircons show heavy loss of Pb. Five spots of zircons near the upper point, yield a weighted mean 207Pb/206Pb age of 3399±8 Ma, representing an age of the sedimentary source. Two groups of zircons from the K-feldspar gneissoid trondhjemite give weighted mean 207Pb/206Pb ages of 2511±13 Ma and 2735±16 Ma respectively. The former represents the emplacement time of the pluton, while the latter is interpreted as the age of the inherited zircons. The new data support that the Archean geological body in the central zone has an affinity with those from the eastern block of the North China Craton.
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