佳木斯地块构造演化

佳木斯地块位于中亚造山带东段,是我国东北地区一个重要的大地构造单元,古生代以来经历了复杂的多构造体系叠合的演化过程。本文在总结近二十年已报导的相关研究成果基础上,结合笔者近年工作,探讨了佳木斯地块的基底属性和来源,重塑了佳木斯地块西缘碰撞拼贴,以及东缘俯冲-增生的构造演化过程。研究表明,佳木斯地块具有亲冈瓦纳大陆的构造属性,裂离后经历了长距离的北漂。与松辽地块先后两次拼合,首次发生于中志留世(～425Ma),在晚二叠世前后(～250Ma)沿原缝合带位置发生裂解,拉张出新的有限洋盆(牡丹江洋),并于侏罗纪(185～145Ma)与松辽地块沿牡丹江-依兰构造带再次碰撞拼贴,形成了高压变质的黑龙江增生杂岩带。而佳木斯地块东缘受晚石炭世-晚三叠世(305～250Ma)泛大洋的俯冲-增生事件影响,形成了跃进山增生杂岩,随后于中侏罗世-早白垩世(165～128Ma)在古太平洋板块的西向俯冲作用下,形成了饶河增生杂岩。因此,佳木斯地块的构造演化既涉及了晚古生代古亚洲洋构造域的消亡,又经历了中生代古太平洋构造域的叠加与改造,而黑龙江杂岩的形成标志着古太平洋构造体制与古亚洲洋构造体制的转换始于晚三叠世(～210Ma)。

Tectonic evolution of the Jiamusi Block, NE China

The Jiamusi Block, located in the eastern part of the Central Asian Orogenic Belt (CAOB), is one of the important tectonic units in Northeast China (NE China). It has experienced a complicated evolutional history corresponding to the overprinting processes of multiple tectonic regimes since Paleozoic. By systematically reviewing of the previous works in the past two decades, and combining with our recent work, this paper discusses the basement properties and origin of the Jiamusi Block, and reconstructs the tectonic model of amalgamation process in the western margin of the Jiamusi Block, as well as the subduction-accretion event developed in its eastern margin. The results presented here, show that the Jiamusi Block was likely a part of the Gondwana Super-continent and drifted a long distance to the north after dispersion of the Gondwana. The Jiamusi Block probably had been docked to the Songliao Block in the Mid-Silurian (ca.425Ma), but broken apart from the Songliao Block in the Late-Permian (ca.250Ma), forming a new narrow ocean basin (so-called Mudanjiang Ocean), and finally collided back again in the Jurassic (185~145Ma) along the Mudanjiang-Yilan suture zone, linking to the formation of the high-P/T metamorphic Heilongjiang Complex. In addition, the eastern margin of the Jiamusi Block involved two subduction-accretion processes, that are the Panthalassa Plate subduction occurred in the Late-Carboniferous to Late-Triassic (305~250Ma), forming the Yuejinshan accretionary complex, and followed by the Paleo-Pacific Plate subduction in the Mid-Jurassic to Early Cretaceous (165~128Ma), forming the Raohe accretionary complex. In summary, the tectonic evolution of the Jiamusi Block is not only related to the extinction of the Paleozoic Paleo-Asian tectonic domain, but also related to the superposition of the Mesozoic Paleo-Pacific tectonic domain. More significantly, the formation of the Heilongjiang Complex possibly reveals that the transformation of the Paleo-Pacific tectonic system and the Paleo-Asian tectonic system took place in the Late-Triassic (ca.210Ma).