The zircon U-Pb age of rhyolite gravel from Shoushangou Formation in Xi Ujimqin Banner,Inner Mongolia and its geological significance
In order to study the Early Permian tectonic setting in the middle of Xing'anling-Mongolian Orogen and discuss the final closure time of the Paleo Asian Ocean,the rhyolitic conglomerate of Shoushangou Formation and the rhyolitic rocks of Dashizhai Formation in the Haorehada area of Xi Ujimqin Banner,Inner Mongolia,were studied by sedimentary geological analysis and zircon U-Pb isotopic geochronology.The zircon U-Pb age of the rhyolite gravel is(280.0±1.9)Ma,the age of the rhyolite is(276.0±1.9)Ma,indicating that the sedimentary time limit of the rhyolitic conglomerate of Shoushangou Formation in the Haorehada area of Xi Ujimqin Banner is between 280 and 276 Ma,with the main deposition epoch being the Kungurian stage of Early Permian;The age of rhyolite gravel and sedimentary time of rhyolitic conglomerate in the Shoushangou Formation are highly consistent with the rhyolite of Dashizhai Formation in the southern part of study area,indicating that the volcanic rocks of Dashizhai Formation in the south area are one of sources of Shoushangou Formation,and they are contemporaneous difference facies.The characteristics of rock assemblage and Sedimentary structures indicate that the rhyolitic conglomerate of Shoushangou Formation is turbidite;According to the temporal and spatial distribution characteristics of the sources of Shoushangou Formation and the previous data,considering that the Shoushangou Formation is the sedimentary product of Back-arc basin,which confirms that the eastern section of the Paleo Asian Ocean was not closed in the Early Permian.
Xing'anling-Mongolian Orogenrhyolite gravelShoushangou FormationDashizhai Formationzircon U-Pb age
NETL
NSTL
万方数据
