敦化-密山断裂带的平移距离：来自松嫩-张广才岭-佳木斯-兴凯地块古生代-中生代岩浆作用的制约

The offset distance of the Dunhua-Mishan Fault: Constraints from Paleozoic-Mesozoic magmatism within the Songnen-Zhangguangcai Range, Jiamusi, and Khanka massifs

敦化-密山断裂带是郯庐断裂北段的重要分支之一,其大规模左行走滑发生的时限以及平移距离一直存在较大争议。本文系统地总结了松嫩-张广才岭地块东缘、佳木斯地块以及兴凯地块之上古生代-中生代火成岩的锆石U-Pb年代学资料,结合其空间分布特征,对敦化-密山断裂带的平移时限及距离提供了制约。研究表明,松嫩-张广才岭地块东缘与兴凯地块在古生代-中生代期间具有类似的岩浆活动历史,两个地块之上该时期的岩浆作用可以划分为8个主要期次：中-晚寒武世（ca.500-516Ma）、早奥陶世（ca.480-486Ma）、晚奥陶世（ca.450-456Ma）、中志留世（ca.426-430Ma）、早二叠世（ca.285-292Ma）、晚二叠世（ca.255-260Ma）、晚三叠世（ca.202-210Ma）和早侏罗世（ca.185-186Ma）。相比之下,佳木斯地块中的古生代-中生代早期岩浆事件则集中在晚寒武世（-492Ma）、晚泥盆世（-388Ma）、早二叠世（-288Ma）、晚二叠世（-259Ma）和早侏罗世（-176Ma）,而晚奥陶世-志留纪和晚三叠世的岩浆活动在佳木斯地块未见报道。早白垩世晚期（ca.105-110Ma）和晚白垩世（ca.90-94Ma）的岩浆活动在三个地块均存在。上述结果表明兴凯地块东缘与松嫩-张广才岭地块东缘在早古生代经历了共同的地质演化历史,而中生代早期,兴凯地块西缘与松嫩-张广才岭地块东缘经历了同样的岩浆作用历史。上述结果暗示,敦化-密山断裂可能经历了至少两次平移,分别发生在中-晚二叠世-早三叠世和中-晚侏罗世-早白垩世,推测其总的平移距离约400km。结合研究区中生代期间的构造演化历史,敦化-密山断裂中生代的左行平移应与中-晚侏罗世-早白垩世期间古太平洋板块（Izanagi板块）的斜向俯冲相联系。

The Dunhua-Mishan Fault is one of important branches of the northern segment of Tan-Lu Fault,its distance and age of large-scale sinistral strike-slip faulting remains a hot debate. In this study,the geochronological data of the Paleozoic-Mesozoic igneous rocks within the Songnen-Zhangguangcai Range,Jiamusi,and Khanka massifs,together with their spatial and temporal variations,provide close constraints in this regard. Geochronological data suggest that the eastern margin of the Songnen-Zhangguangcai Range and Khanka massifs share a common magmatic history during Paleozoic to Mesozoic. The Paleozoic-Early Mesozoic magmatism within the mentioned-above two massifs can be divided into eight stages,i. e.,Middle-Late Cambrian（ ca. 500 - 516Ma）,Early Ordovician（ ca. 480 - 486Ma）,Late Ordovician（ ca. 450 - 456Ma）,Middle Silurian（ ca. 426 - 430Ma）,Early Permian（ ca. 285 - 292Ma）,Late Permian（ ca. 255 - 260Ma）,Late Triassic（ ca. 202 - 210Ma） and Early Jurassic（ ca. 185 - 186Ma）. By comparison,PaleozoicEarly Mesozoic magmatic events within the Jiamusi Massif concentrate in Late Cambrian（ - 492Ma）,Late Devonian（ - 388Ma）,Early Permian（ - 288Ma）,Late Permian（ - 259Ma）,and Early Jurassic（ - 176Ma）,respectively. The igneous rock with Late Ordovician-Silurian and Late Triassic ages is not yet identified in the Jiamusi Massif. In addition,the late-stage of Early Cretaceous（ ca. 105 - 110Ma） and Late Cretaceous（ ca. 90 - 94Ma） igneous rocks coexisting in mentioned-above three massifs. These results indicate that the eastern margins of the Songnen-Zhangguangcai Range and Khanka massifs experienced common geological evolution during Early Paleozoic,and the western margin of the Khanka Massif and the eastern margin of the Songnen-Zhangguangcai Range Massif experience the common magmatic history in the Early Mesozoic. These findings suggest that Dunhua-Mishan Fault have undergone at least two-stage strike slip faulting,i. e.,the Middle-Late Permian to Early Triassic and Middle-Late Jurassic to Early Cretaceous; the total offset distance was approximately 400 km. Combining with the Mesozoic tectonic evolution in study area,the leftlateral displacement of the Dunhua-Mishan Fault was related with the oblique subduction of the Paleo-Pacific Plate（ Izanagi） during Middle-Late Jurassic to Early Cretaceous.