地质通报2013，Vol.32Issue(8)：1260-1268,9.
内蒙古西乌珠穆沁旗地区下二叠统原寿山沟组碎屑锆石LA-ICP-MS U-Pb年龄及地质意义
U-Pb age of detrital zircons from Early Permian"Shoushangou Formation" in Xi Ujimqin Banner, Inner Mogolia
摘要
Abstract
The "Shoushangou Formation",previously assigned to lower Permian,is widespread in southern Da Hinggan Mountains.The Tabinmiao profile of "Shoushangou Formation" in Xi Ujimqin Banner of Inner Mongolia is characterized by thick rhythmic interbeds comprising medium-to thin-layered mudstones and sandstones.Of them,the sandstones are mainly feldspathic lithic rocks.Zircons from sandstone in the upper sequence of the profile almost display typical structures of magmatic genesis.Eight (ca.9％ of the total 90 dated zircon grains) of the dated zircons yielded Proterozoic to early Paleozoic ages,ranging from 1490Ma to 502Ma.However,the yielded age data of the rest zircons are clustered in three groups:383Ma±3Ma (n=3,ca.3％),365Ma±4Ma (n=6,ca.7％) and between 337Ma and 280Ma (n=73).Four age peaks can be recognized between 337Ma and 280Ma,i.e.,289Ma,300Ma,309Ma and 325Ma.The obtained age data indicate the multi-provenance of the sandstone.Nevertheless,the youngest zircon age constrained the maximum depositional age of 289Ma.According to the isotope age data of Dashizhai Formation,the authors infer that both Shoushangou Formation of this study and Dashizhai Formation belong to different facies of the same period.On the basis of U-Pb dating,it is deduced that the studied "Shoushangou Formation" was not the previously defined Shoushangou Formation,that is,the stratigraphic sequence and its correlation with the lower Permian strata in southern Da Hinggan Mountains need to be re-evaluated.Combined with the regional geology and timing of the magmatism,it is concluded that the detrital zircons of the dated "Shoushangou Formation" mainly came from the Paleozoic granitoids and volcanic rocks in the Xilin Hot-Xi Ujimqin Banner area,with the probable addition of a small amount of volcanic rocks of the Dashizhai Formation.关键词
西乌旗/寿山沟组/碎屑锆石/U-Pb同位素Key words
Xi Ujimqin Banner/ "Shoushangou Formation"/ detrital zircons/ U-Pb isotope分类
天文与地球科学引用本文复制引用
郑月娟,公繁浩,陈树旺,黄欣,张立君,张健..内蒙古西乌珠穆沁旗地区下二叠统原寿山沟组碎屑锆石LA-ICP-MS U-Pb年龄及地质意义[J].地质通报,2013,32(8):1260-1268,9.基金项目
中国地质调查局项目(编号:1212010783001、1212011121086) （编号:1212010783001、1212011121086）
