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    Zircon SHRIMP geochronology and geochemistry of TTG rocks in Sushui Complex from Zhongtiao Mountains with its geological implications [查看] TIANWei、LIUShuwen、LIUChaohui、YUShengqiang、LIQiugen、WANGYueran
    The tonalite-trondhjemite-granodiorite(TTG)rocks in Sushui Complex of Zhongtiao Block can be divided into two series according to their zircon U-Pb ages and geochemical characteristics:one is subduction-related(SR)and the other collision-related(CR).The SR TTG rocks,together with other late Archean island arc magmatism,were developed as a result of oceanic subduction betwween the Eastern and Western blocks in Late Archean;while the CR TTG rocks formed in a thickened crustal envionment,which was responding to the collision between the Eastern and Western blocks in Paleproterozoic.All these features support a model that the Zhongtiao Block is a part of the Trans-North China Orogen in the middle of the North China Craton
    SHRIMP Zircon U-Pb Chronology and Geochemistry of the Henglingguan and Beiyu Granitoids in the Zhongtiao Mountains [查看] YUShengqiang、LIUShuwen、TIANWei、LIQiugen、FENGYonggang
    Abstract：Henglingguan and Beiyu metamorphic granitoids，distributed in the northwest of the Zhongtiaoshan Precambrian complex，comprise trondhjemites and calc-alkaline monzogranites，displaying intrusive contacts with the Archean Zhaizi TTG gneisses．And the Beiyu metamorphic granitoids consist mainlY of trondhjemites，distributed at the core of the Hujiayu anticline fold．New SHRIMP zircon U-Pb dating data show that the weighted mean207Pb/206Pb ages are 2435.9 Ma and 2477 Ma for the Henglingguan metamorphic calc-alkaline monzogranites and Beiyu meta morphic trondhjemites．respectively，and reveal ～2600 Ma inherited core in magmatic zircons．Whole-rock geochemical data indicate that all the Henglingguan and Beiyu metamorphic trondhjemites and calcalkaline monzogranites belong to the metaluminous medium-and high-pota ssium calc-alkaline series．These rocks are characterized by relatively high total alkali contents (Na20+K20，up to 9.08％)，depleted Nb，Ta，P and Ti，and right-declined REE patterns with m oderate to high LREEs/HREEs fractionation (the mean ratio of(La/Yb)n= 25)．The Henglingguan and Beiyu metamorphic trondhjemites display negative Rb．Th and K anomalies in the multi-element spider diagrams normalized by primi tive mantle．Sm-Nd isotopic data reveal that these granitoids have initial Nd(f)=-12 to +24 and Nd depleted mantle model ages of TMD= 2622 Ma-2939 Ma．A11 these geoc hemical features indicate that these granitoids were form ed in an continent-marginal arc and the trondhjemites mainly originated from partial melting of juvenile basaltic materials and，howbeit，the Henglingguan metamorp hic calc-alkaline monzogranites derived from recycling of materials in the ancient crust under a continent-marginal arc．The granitic magma underwent contami nation and fractional crystallization during their formation.
    Paleoproterozoic Potassic Granitoids in the Sushui Complex from the Zhongtiao Mountains,Northern China Geochronology,Geochemistry and Petrogenesis [查看] TIANWei1、LIUShuwen、ZHANGHuafeng
    Abstract: Paleoproterozoic potassic granitoids in the southern Sushui Complex from the Zhongtiao Mountains yielded SHRIMP zircon U-Pb ages of 1968–1944 Ma. Lithologically, the potassic granitoid series consists chiefly of monzodiorite, quartz monzonite and syenogranite. Their trace elements and Sm-Nd isotope characteristics indicate that they were derived from partial melting of Archean TTG rocks in an overthickened continental crust. Petrogenesis of this potassic granitoid series implies a collisional environment within the Trans-North China Orogen in the Paleoproterozoic, which supports a tectonic model of Eastern and Western Continental Blocks being amalgamated in the Paleoproterozoic.
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