中国东北变质基底为由含矽线石榴片麻岩、角闪斜长片麻岩、石墨大理岩和各种长英质片麻岩组成的孔兹岩系。采自额尔古纳、兴安、佳木斯和兴凯地块的矽线石榴片麻岩样品的锆石U-Pb测年均指示高级变质发生在500Ma左右。来自松辽地块古生代沉积物碎屑锆石的证据也表明约500Ma构造岩浆事件的存在。跨越整个中国东北不同地块的泛非期高级变质岩形成了超过1 300km北西向展布的晚泛非期"中国东北孔兹岩带",以顺时针p/T轨迹的孔兹岩带与同期岩浆杂岩共同构成了一巨型的约500Ma前后的造山带,笔者这里命名为"中国东北早古生代造山带"。这证明了中国东北各地块在500Ma之前已经拼合,并与西伯利亚克拉通具有构造亲缘性,曾是晚泛非期(500 Ma)西伯利亚南缘Sayang-Baikal造山带的组成部分。450Ma之后,已经拼合的中国东北地块群从西伯利亚裂解,向南朝现今的中国东北漂移;230Ma前后,东北地块群沿索伦—西拉沐伦—长春缝合带与华北板块碰撞;210~180 Ma,由于太平洋板块的俯冲导致佳木斯地块与西部松辽地块最终拼贴,沿佳木斯—兴凯地块西缘和南缘形成一弧形高压带(包括佳木斯—兴凯地块西缘黑龙江蓝片岩带和佳木斯—兴凯地块南缘长春—延吉带),这里简称"吉林—黑龙江高压变质带",之后东北地区进入了环太平洋构造域演化阶段并持续至今。
The basement rocks in parts of NE China constitute a khondalitic sequence of sillimanite-and garnet-bearing gneisses,hornblende-plagioclase gneiss and various felsic paragneisses.Zircon U-Pb dating of garnet-sillimanite gneiss samples from the Erguna,Xing'an,Jiamusi and Khanka blocks all indicate that high-grade metamorphism occurred at ~500 Ma.Evidence from detrital zircons in Paleozoic sediments from the Songliao block also indicates the former presence of a ~500 Ma component.This uniformity of U-Pb ages across all crustal blocks in NE China establishes a1 300 km long Late Pan-African khondalite belt with Pan-African syn-collisional granite,which we named here the 'NE China Pan-African Orogen'.This indicates the blocks of NE China were amalgamated prior to ~500 Ma,contrary to current belief.One scenario is that this amalgamated terrane had a tectonic affinity to the Siberia craton,once forming part of the Late Pan-African(~500 Ma) Sayang-Baikal orogenic belt extensively developed around the southern margin of the Siberia craton.This belt was the result of collision between currently unidentified terranes with the Southeastern Angara-Anabar Province at about 500 Ma,where the rocks were deformed and metamorphosed to granulite facies.It appears likely that at sometime after ~450 Ma,the combined NE China blocks rifted away from Siberia and moved southward to form what is now NE China.The combined block collided with the North China craton along the Solonker-XarMoron-Changchun suture zone at ~230 Ma rather than in the end-Permian as previously thought.Local rifting at the eastern extremity of the developing Central Asian orogenic belt(CAOB) resulted in the splitting away of the Jiamusi/Khanka(/Bureya) blocks.However,this was only transient and sometime between 210 and 180 Ma,and these were re-united with the CAOB by the onset of Pacific plate subduction,which we named here the "Jilin-Heilongjiang high pressure belt" and forming which has dominated the tectonic evolution of the region since that