Geochronology,Eruption Sequence and Geochemistry of Mid-Late Jurassic Volcanics South of Manzhouli:Petrogenesis and Implications for Mesozoic Tectonic Regime Transformation  

作　　者：BAI Yuling WANG Tao WANG Zongqi YAN Jie ZHANG Ai 

机构地区：[1]Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China [2]Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China [3]Inner Mongolia Key Laboratory of Magmatic Mineralization and Ore-Prospecting,Hohhot 010020,China [4]Mineral Exploration Technical Guidance Center,Ministry of Natural Resources,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第4期1112-1131,共20页地质学报（英文版）

基　　金：financially supported by the Geological Survey program of China Geological Survey(Grant Nos.DD20189613,12120115031301);National Key Research and Development Program of China(Grant No.2019YFC0605202)。

摘　　要：To the south of Manzhouli,Hulunbuir,Inner Mongolia,experienced a tectonic regime transformation from compression to extension in the mid-Mesozoic.Based on systematic research of the volcanics,petrology,volcanic facies,chronology and geochemistry of rocks in the Buridun area,two stages of volcanics are identified.The first stage named the trachyte series was formed in the late Middle Jurassic(167-163 Ma),its eruption rhythm is pyroxene trachyandesite-trachyandesite-trachyte,and its origin rock is basic volcanics from thickened lower crust,with a tectonic setting in the collision orogeny after the closure of the Mongolia Okhotsk Ocean(MOO).The second stage is a bimodal volcanic rock,formed in the early Late Jurassic(163-160 Ma).The eruption rhythm of basic volcanics in this stage is basaltic andesite-basalt-olivine basalt,which comes from the metasomatized lithospheric mantle,the acidic volcanics of which being characterized by the eruption rhythm of sedimentary-explosive-overflow facies,which came from the partial melting of newly formed lower crust,and this shows the characteristics of A-type granite;the tectonic setting is extension of the lithosphere after collision and closure of the MOO.The changes in the formation age and tectonic setting of the two stages of volcanics demonstrate that the transition time from the compressive system to the extensional system south of Manzhouli is about 163 Ma.

关 键 词：tectonics GEOCHRONOLOGY Middle-Late Jurassic volcanics eruption sequence Inner Mongolia 

分 类 号：P588.14[天文地球—岩石学] P534.52[天文地球—地质学] P597.3