黑龙江省东部松嫩—张广才岭地块与佳木斯地块之间的演化历史以及古亚洲洋构造体系与环太平洋构造体系的叠加与转化一直是地学领域研究的热点问题之一。依据该区古生代—早中生代火成岩的年代学与岩石组合研究,结合碎屑锆石的年代学研究成果,讨论了松嫩—张广才岭地块与佳木斯地块之间的演化历史以及两大构造体系叠加与转化的时间。锆石U-Pb定年结果表明:黑龙江省东部古生代—早中生代岩浆作用可划分成8期:早奥陶世(485Ma)、晚奥陶世(450Ma)、中志留世(425Ma)、中泥盆世(386Ma)、早二叠世(291Ma)、中二叠世(268 Ma)、晚三叠世(201~228 Ma)以及早侏罗世(184 Ma)。早奥陶世—中志留世,岩浆作用主要分布在松嫩—张广才岭地块的东缘,并呈南北向带状展布,主要由闪长岩-英云闪长岩-二长花岗岩组成,显示活动陆缘—碰撞的构造演化历史,揭示松嫩—张广才岭地块与佳木斯地块于中志留世(425Ma)已经拼合在一起,这也得到了早泥盆世地层碎屑锆石年代学的支持。中泥盆世,火山作用分布在佳木斯地块东缘和松嫩—张广才岭地块上,前者为双峰式火山岩组合,后者为A型流纹岩,它们共同揭示该区处于一种碰撞后的伸展环境。早二叠世,佳木斯地块东缘发育一套钙碱性火山岩组合,揭示古亚洲洋俯冲作用的存在,而同期的张广才岭地区则发育一套典型的双峰式火成岩组合,揭示了陆内伸展环境的存在。中二叠世,同碰撞型火山岩分布于佳木斯地块东缘及东南缘,其形成可能与佳木斯地块和兴凯地块的碰撞拼合有关。晚三叠世,张广才岭地区存在的双峰式火山岩和敦—密断裂东南区发育的A型流纹岩均显示陆内的伸展环境,其形成应与古亚洲洋最终闭合后的伸展环境相联系。此外,结合牡丹江断裂两侧均发育中—晚二叠世花岗岩以及佳?
It remains a topic of debate that the tectonic evolution between the Songnen-Zhangguangcai Range and Jiamusi massifs and the timing of transformation from the Paleo-Asian Ocean to the circum-Pacific tectonic systems in the eastern Heilongjiang Province.In the present study,the geochronology and rock association of the Paleozoic-Early Mesozoic igneous rocks in the study area,combined with geochronological data of detrital zircons,provide strong constraints in this regard.LA-ICP-MS zircon U-Pb dating results indicate that the Paleozoic-Early Mesozoic magmatism in the eastern Heilongjiang Province can be divided into eight stages,i.e.,the Early Ordovician(485 Ma),Late Ordovician(450 Ma),Middle Silurian(425 Ma),Middle Devonian(386 Ma),Early Permian(291 Ma),Middle Permian(268 Ma),Late Triassic(201-228 Ma),and Early Jurassic(184 Ma).The Early Ordovician-Middle Silurian magmatism,occurred in eastern margin of the Songnen-Zhangguangcai Range Massif with the obvious south-north-trend,is composed mainly of diorite,tonalite,and monzogranite,which formed in the subduction-collision tectonic setting,implying that the amalgamation between the Songnen-Zhangguangcai Range and Jiamusi massifs finished in the Middle Silurian(425 Ma).It is also supported by the geochronological data for detrital zircons from Early Devonian sedimentary rocks in study area.Middle Devonian volcanism is composed mainly of a series of bimodal volcanic rocks in eastern margin of the Jiamusi massif and the A-type rhyolite in the Songnen-Zhangguangcai Range massif,suggesting a post-collisional extensional environment.Early Permian calc-alkaline volcanic rocks,occurred in eastern margin of the Jiamusi massif,imply that the subduction of the Paleo-Asian Oceanic plate happened beneath the Jiamusi massif,whereas the coeval bimodal igneous rocks,occurred in the Songnen-Zhangguangcai Range massif,suggest an extensional environment similar to back-arc setting.The formation of Middle Permian syn-collisional volcanic rocks in sou