内蒙古索伦山蛇绿岩带早二叠世放射虫动物群的发现及其地质意义  

Discovery of Early Permian radiolarian fauna in the Solon Obo ophiolite belt, Inner Mongolia and its geological significance

作　　者：李钢柱[1] 王玉净[2] 李成元[1] 白宇明[1,3] 薛建平[1,3] 赵广明[1] 薄海军 梁月升 刘伟[1] 

机构地区：[1]武警黄金第二支队,呼和浩特010010 [2]中国科学院南京地质古生物研究所,南京210008 [3]中国地质大学地球科学与资源学院,北京100083

出　　处：《科学通报》2017年第5期400-406,共7页Chinese Science Bulletin

基　　金：中国地质调查局地质调查项目(12120113071800)资助

摘　　要：位于中蒙边境地区的索伦山蛇绿岩带,是古生代存在于西伯利亚板块与华北板块之间的古亚洲洋闭合之后形成的索伦山缝合带的重要组成部分.索伦山蛇绿岩的研究,对认识古亚洲洋演化具有重要意义,但其时代一直是学术界争论的焦点问题之一.本次工作采集索伦山蛇绿岩带硅质岩样品,对其进行了放射虫化石的分选与鉴定.在内蒙古乌拉特中旗北部靠近中蒙边境线的索伦山蛇绿岩带硅质岩中发现早二叠世放射虫动物群,包括5个属6个种,其中有4个未定种和1个新种:Pseudoalbaillella bulbosa,Ps.solonensis Wang sp.nov.,Stigmosphaerostylus sp.,Ruzhencevispongus sp.,Cenosphaera sp.,Latentifistula sp.等.Pseudoalbaillella bulbosa这个种在日本、泰国、智利、北美西海岸和中国华南等地发现在晚石炭世-早二叠世硅质岩相地层中,在中国作为早二叠世早期的一个带种,成为广海相硅质岩相区石炭系与二叠系分界的标志.这套放射虫硅质岩属索伦山蛇绿岩的组成部分,该动物群的发现为索伦山蛇绿岩形成时间持续到早二叠世提供了关键证据.这些新证据证实了古亚洲洋在早二叠世时仍存在,古亚洲洋通过俯冲消减最终闭合应是在早二叠世之后.The Solon Obo ophiolite belt in Inner Mongolia is located close to the border between China and Mongolia. It is an integral part of the Solon Obo tectonic suture formed by the closure of the Paleo-Asian Ocean between Siberia Craton and North China Craton in the Paleozoic. This ophiolite belt is a rare remnant of the Paleo-Asian Ocean and thus provides important samples for the study of tectonic evolution in the eastern part of the Central Asian Orogenic Belt in North China. The age of the tectonic event of the Solon Obo tectonic suture has been debated for a long time. Some researchers believe that it was from Silurian to Devonian whereas other researchers believe it was from Early Carboniferous to Early Permian. Here we report the first discovery of Early Permian radiolarians in the cherts of the ophiolite belt. The Solon Obo ophiolite belt is E-W trending, with a total length of -100 km. It is mainly composed of ultramafic intrusive rocks such as harzburgite, lherzolite, dunite and pyroxenite, and gabbro, diabase, basalts and cherts. On the base of the field geological investigation and 1：10000 structure-lithology mapping in the Solon Obo area, we took cherts samples from the Solon Obo ophiolite belt in the Subuergen Hudag area of northern Urad Middle Banner, Inner Mongolia, and carried out studies including petrologic characteristics of cherts, separation and identification of the radiolarian fossils in cherts. Early Permian radiolarian fauna is first found in the chert of Solon obo ophiolite belt. This fauna is composed of 5 genera and 6 species（including 4 unidentified species and 1 new species）, Pseudoalbaillella bulbosa, Ps. solonensis Wang sp. nov., Stigmosphaerostylus sp., Ruzhencevispongus sp., Cenosphaera sp., Latentifistula sp. etc. The new species, Pseudoalbaillella solonensis can be distinguished from Ps. u-forma by its holes in the end of the pseudoabdominal segment. Pseudoalbaillella bulbosa, found in Late Carboniferous-Early Permian cherty strata of Japan, Thailand, Chile, Western Coast of

关 键 词：放射虫 早二叠世 蛇绿岩 索伦山 古亚洲洋 

分 类 号：Q915[天文地球—古生物学与地层学] P534.46[生物学—古生物学]