兴蒙造山带前中生代构造单元划分初探  

Preliminary study on the pre-Mesozoic tectonic unit division of the Xing-Meng Orogenic Belt( XMOB)

作　　者：徐备[1] 赵盼[1] 鲍庆中[2] 周永恒[2] 王炎阳 罗志文[1] 

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室、北京大学地球与空间科学学院,北京100871 [2]沈阳地质矿产研究所,沈阳110034

出　　处：《岩石学报》2014年第7期1841-1857,共17页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划(2013CB429806);国家自然科学基金项目(40872145、41121062);中国地质调查局项目(1212011220906)联合资助

摘　　要：本文根据古亚洲洋早古生代闭合、晚古生代伸展的观点初步建立了兴蒙造山带早、晚古生代的构造单元。以前寒武纪微陆块为基本划分单位,以它们之间的缝合带或断裂带为界,将兴蒙造山带中泥盆世之前的构造格局划分为"五块四带",从北向南依次为额尔古纳地块、兴安地块、艾力格庙-锡林浩特地块、松辽-浑善达克地块及佳木斯地块;它们之间的4条边界为:新林-喜桂图缝合带、艾力格庙-锡林浩特-黑河缝合带、温都尔庙-吉中-延吉缝合带和牡丹江缝合带。中-晚泥盆世之后兴蒙造山带出现多处陆相及海陆交互相沉积,石炭纪广泛分布陆相及滨浅海相碎屑岩和碳酸盐建造和蛇绿岩、辉长岩、花岗岩及双峰式火山岩,可划分陆相盆地、陆表海盆地、蛇绿岩带、侵入岩带等构造单元。早-中二叠世沉积类型多变,出现陆相、海相和海陆交互相沉积岩系,遍含植物和滨浅海相动物化石,具大量双峰式火山岩,可划分出被动裂谷带、主动裂谷带、陆缘型蛇绿岩带和碱性岩带等构造单元。结尾讨论中指出兴蒙造山带内的放射虫化石不能代表二叠纪存在古亚洲洋,而新的古地磁资料支持至少从晚石炭世以来古亚洲洋已经闭合。According to the viewpoint that the paleo-Asian ocean closed by the end of Early Paleozoic and extended during the Late Paleozoic, a pre-Mesozoic tectonic unit division has been suggested. Five blocks and four sutures have been recognized in the pre- Devonia stage, the five blocks are called Ergnna （EB）, Xing＇ an （XB）, Airgin Sum-Xilinhot （AXB）, Songliao-Hunshandak （SHB） and Jiamusi （JB） blocks and four sutures, Xinlin-Xignitu （XXS）, Airgin Sum-Xilinhot-Heihe （AXHS）, Ondor Sum-Jizhong-Yanji （OJYS） and Mudanjiang （MS） sutures. The EB contains the Precambrian basement with the ages of 720 - 850Ma and εHf （t） = ＋ 2.5 to ＋8. 1. The XB is characterized by the Paleoproterozoic granitic gneiss with εHf（t） = -3.9 to 8. 9. Several ages from 1150Ma to 1500Ma bave been acquired in the AXB, proving presence of old block that links with Hutag Uul block in Mongolia to the west. The Paleoproterozoic （1.8 - 1.9Ga） and Neoproterozoic （750 -850Ma） ages have been reported from southern and eastern parts of the SHB, respectively, which suggests occurrence of a Precambrian block. As a small block in east margin of the XMOB, the JB outcrops magmatite and granitic gneiss bases with ages of 800-1000Ma. The XXS is marked by blueschists with zircon ages of 490 -500Ma in Toudaoqiao village, ophiolites in Xignitu County and granite with ages of about 500Ma along the northern segment of XXS. The AXHS is characterized by the Early Paleozoic arc magmatic rocks with ages from 430Ma to 490Ma, melange and the Late Devonia molass basins, which indicates a northward subduction of the SHB beneath the AXB during the Early-Middle Paleozoic. The OJYS is composed of the Early Paleozoic volcanic rocks, diorites and granites with ages of 425 - 475 Ma, blueschists, ophiolitic melange, the Late Silurian flysch and Early-Middle Devonian molasses in western segment, granites （420 - 450Ma） in middle segment, and plagiagranites （443Ma） and the Late Silurian molasses in eastern segment. This sut

关 键 词：大地构造单元 兴蒙造山带 中国北方 前中生代 

分 类 号：P544[天文地球—构造地质学]