阿鲁科尔沁旗陶海营子剖面是林西组的典型剖面之一,岩性为灰、灰黑、黄绿色的砂板岩组合,含双壳、叶肢介、植物和孢粉化石,时代为晚二叠世晚期。砂岩的主体岩石类型为长石岩屑砂岩。对采自剖面下部第1层的长石岩屑砂岩进行了LAICP-MS锆石U-Pb同位素测定。结果显示,96颗锆石的谐和年龄分布在6个年龄区间:248~301Ma(40颗,42%),峰值年龄为261Ma;312~376Ma(12颗,13%),峰值年龄为330Ma和375Ma;417~522Ma(14颗,15%),峰值年龄为510Ma、438Ma和472Ma;585~988Ma(18颗,19%),峰值年龄为927Ma、976Ma和856Ma;1091~1548Ma(7颗,7%)和1791~2671Ma(5颗,5%)。最年轻的3个和谐年龄为248Ma±5Ma、253Ma±5Ma、254Ma±5Ma,最年轻的次峰值年龄为253Ma,推测测年样品沉积时间下限为253Ma。最年轻的峰值年龄(253Ma、261Ma)与华北板块北缘和大兴安岭南部西拉木伦河缝合带附近与板块碰撞、拼贴相关的岩浆事件吻合。结合古生物地理学的研究成果,推测林西组的沉积物源除来自于西拉木伦缝合带北部的东北地区外,也可能来自西拉木伦缝合带南部,华北板块与西伯利亚板块在晚二叠世晚期拼合,古亚洲洋消失。
The Taohaiyingzi geological section of the Linxi Formation in Ar Horqin Banner of Inner Mongolia is one of the typical sections in the north part of eastern China. The age of the section is late Late Permian according to the newly found conchostracans, pollen and spores. The Linxi Formation in Taohaiyingzi consists mainly of black and grayish black sandstone and slate association, with the sandstones being mainly feldspathic lithic rocks. Zircons from sandstone in the lower part of the section exhibit typical struc-tures of magmatic genesis. LA-ICP-MS U-Pb dating of 96 zircons yielded six age populations: 248~301Ma (n=40, ca. 42%) with the peak age at 261Ma;312~376Ma (n=12, ca. 13%) with the peak ages at 330Ma and 375Ma;417~522Ma (n=14, ca. 15%) with the peak ages at 510Ma, 438Ma and 472Ma; 585~988Ma (n=18, ca. 19%) with the peak ages at 927Ma, 976Ma and 856Ma; the fifth group (n=7, ca. 7%) comprising 1091Ma, 1196Ma, 1198Ma, 1207Ma, 1368Ma, 1425Ma and 1548Ma;the sixth group (n=5 ,ca. 5