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    SHRIMP U-Pb zircon dating on Nyainquetanglha granite in central Lhasa block [查看] LIUQisheng、WUZhenhan、HUDaogong、YEPeisheng、JIANGWan、WANGYanbin、ZHANGHancheng
    Abstract The Nyainqentanglha granite, a batholith with an area of 1500 km2 in the central Lhasa block, comprises mainly medium-fine-grained biotite monzonitic granite and medium-coarse-grained biotite monzonitic granite. Their contact relationship suggests that the medium-fine-grained biotite monzonitic granite was crystallized earlier than the medium-coarse-grained monzonitic granite. A SHRIMP U-Pb dating on zircons from representative samples of the batholith shows that the crystallization age of the medium-fine-grained biotite monzonitic granite is 18.3 Ma and that of the medium-coarse-grained monzonitic granite is 11.01 Ma. The emplacement and crystallization of the Nyainqentanglha granite, the youngest granite batholith ever known inside the Lhasa block, have a close relationship with the collisional orogeny, crustal thickening, plateau uplifting,E-W crustal extension and have a dynamic genetic relationship with the crustal partial melting.
    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．
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