华北板块北缘东段法库地区早古生代弧岩浆活动及其构造演化特征

Many data have been reported from the Early Palaeozoic subduction complex belt and accretionary arc to the south of the Solonker‐Xar Moron‐Changchun‐Yanji Suture (SXCYS) zone. These reports are mainly concentrated in the western segment of the north margin of the North China Craton (NCC) and a small amount of exposure in the central Jilin province which belongs to the eastern segment of the north margin of the NCC. However, as the suture is covered to the east by the Mesozoic–Cenozoic Songliao Basin, there have yet been no related reports about the Early Palaeozoic igneous rocks in this area. Recently, the applicant has discovered Early Paleozoic magmatic records in the Faku area of Northern Liaoning (the songliao basin overlying area in the eastern segment of the north margin of the NCC), and some preliminary research results have been achieved. This project, through field geological survey, intends to conduct a deep study of rock assemblage, spatial distribution and contact relationship, and systematically collect relevant samples. Zircon U-Pb dating, 39Ar/40Ar isotope dating, petrogeochemistry, Lu-Hf, and Sr-Nd isotopes were used to study their chronology, petrogenesis, and properties of the source of the rock.etc. This study will provide strong evidence for the Early Paleozoic tectonic evolution of the Songliao Basin overlying area in the eastern segment of the north margin of the NCC, as well as important clues and direct evidence for the regional tectonic evolution and the solution of key geological problems in the future.

沿华北板块北缘，索伦-西拉木伦河缝合带南侧报道了很多早古生代俯冲杂岩带及增生弧的数据，这些报道主要集中在华北板块北缘西段及华北板块北缘东段吉林中部地区少量出露，但因索伦-西拉木伦缝合带沿西拉木伦河向东被松辽盆地所掩盖，该区目前尚无早古生代火成岩的相关报道。申请人在辽宁北部法库地区（华北板块北缘东段松辽盆地覆盖区）发现了早古生代相关岩浆岩记录，并取得了一些初步的研究成果。本课题拟通过野外地质调查，深入研究岩石组合、空间展布、接触关系，并系统收集相关样品，采用锆石U-Pb定年、39Ar/40Ar同位素测年、岩石地球化学、Lu-Hf及Sr-Nd同位素等测试手段，研究其年代学、岩石成因、源岩性质、动力学背景等，该研究将为华北板块北缘东段松辽盆地覆盖区早古生代构造演化提供有力佐证，同时可以为今后开展区域构造演化及解决关键地质问题提供重要线索和直接证据。

本项研究针对辽宁北部地区早古生代火山岩及深成侵入岩通过野外地质调查，结合岩石学、矿物学、锆石U-Pb年代学、全岩-锆石元素-同位素地球化学等系统研究，查明了辽宁北部地区早古生代地质体的岩石组合、形成时代、空间展布特征，确定了其岩石成因、源区性质及构造背景，探讨了华北板块北缘东段早古生代构造演化史。取得的主要认识如下：（1）根据老陵山晚奥陶世变玄武安山岩（458±2.1Ma）的地球化学特征显示，其属于中钾钙碱性-低钾拉斑系列，岩浆起源于受俯冲流体交代的岩石圈地幔的部分熔融，形成于洋内弧环境，暗示该期间，古亚洲洋板块内部存在俯冲作用；（2）因研究区志留纪岩体的位置随着其形成时代的变新而有序的向北增生产出，结合区域地质事件，综合认为古亚洲洋板片应是自北向南俯冲至华北板块北缘之下；（3）根据在研究区发现的一系列志留纪埃达克质岩体（437~432Ma）以及同碰撞S型花岗岩（425Ma）认为，志留纪期间，在古亚洲洋洋壳消减作用下，华北板块北缘与古亚洲洋内岛弧发生过一次弧-陆碰撞作用，伴随强烈的碰撞造山作用，导致了华北板块北缘地壳的增厚。