中国东北地区蛇绿岩

我国东北地区位于中亚造山带的东段,经历了复杂的增生造山过程,其所属微陆块的基底属性及拼贴位置、洋-陆转换一直是地学界研究的热点。根据近年来的研究进展,我们将东北地区微陆块划分为额尔古纳地块、兴安增生地体、松嫩-锡林浩特地块和佳木斯地块。同时综述了东北地区蛇绿岩/蛇绿混杂岩带的时空分布、年代学及地球化学的新资料,讨论了其构造背景及俯冲-增生过程。东北地区增生造山不仅涉及古亚洲洋和古太平洋,还可能与泛大洋有关,包括早奥陶世-晚三叠世古亚洲洋主洋盆及古亚洲洋分支——新元古代-晚寒武世新林-喜桂图洋、早寒武世-晚石炭世嫩江洋、新元古代-晚志留世黑龙江洋和晚二叠世-中侏罗世牡丹江洋的演化。早石炭世末-晚石炭世初,东北地区古亚洲洋分支洋盆全部闭合,所有微陆块完成聚合形成统一的东北陆块群。晚二叠世-早三叠世时期,古亚洲洋主洋盆沿索伦-西拉木伦-长春-延吉缝合带自西向东从早到晚以剪刀式最终闭合,完成东北陆块群与华北板块的拼接。晚三叠世-早侏罗世时期古太平洋板块俯冲启动,东北地区进入古太平洋俯冲增生构造体系。

Ophiolite in the eastern Central Asian Orogenic Belt, NE China

Northeast China is located in the eastern segment of the Central Asian Orogenic Belt, which underwent complicated accretionary orogenic processes. It has become hot topics to understand the basement features and their collision boundary locations and timing of the micro-massifs. Based on the research progresses in the recent years, we recognized Erguna Massif, Xing''an Accretionary Terrane, Songnen-Xilinhot Massif and Jiamusi Massif in the NE China. The ages, geochemistry and distributions of the ophiolites/ophiolitic complexes as the markers of the suture zones have been reviewed according to the updated data, the tectonic setting and subduction-accretion processes have been discussed. The accretionary orogeny was related to Paleo-Asian Ocean, Paleo-Pacific Ocean and Pan-Ocean. The subduction-accretion processes include the evolutions of the Early Ordovician-Late Triassic main branch of Paleo-Asian Ocean, Neoproterozoic-Late Cambrian Xinlin-Xiguitu branch ocean, the Early Cambrian-Late Carboniferous Nenjiang branch ocean and Neoproterozoic Heilongjiang branch ocean and Late Permian-Middle Jurassic Mudanjiang branch ocean. In the end of Early Carboniferous to the beginning of Late Carboniferous all the branch oceans were closed, an amalgamated block in the NE China had been formed. In the Late Permian-Early Triassic, the main Paleo-Asian Ocean basin was closed in scissor style from west to east along Solonker-Xar Moron-Changchun-Yanji suture zone, and the amalgamated block was connected to the North China Plate. The NE China started to be subducted and accreted by Paleo-Pacific Ocean in the Late Triassic-Early Jurassic.