吉林省前寒武纪地层

The Precambrian strata of Jilin Province

吉林省前寒武纪地层可见有太古宙变质表壳岩系、古元古代中深变质火山-沉积岩系、吉南新元古代陆源碎屑岩-碳酸盐岩组成的盖层沉积岩系和吉北造山带新元古代变质火山-沉积岩系4种类型.其中太古宙地层龙岗陆块具有多陆块拼贴的特点,可划分为龙岗岩群(四道砬子河岩组、杨家店岩组)、夹皮沟岩群(三道沟岩组、老牛沟岩组)、板石沟岩群、南岗岩群(鸡南岩组、官地岩组)、清原岩群.分别代表白山镇地块、夹皮沟镇地块、板石沟地块、和龙地块和清原地块的变质表壳岩系,其中除龙岗岩群可能为中太古代外,其余地质体的时代均为新太古代.古元古代地层有集安岩群、光华岩群和老岭岩群,前两者为古元古代早期裂谷环境沉积,分别可进一步划分为蚂蚁河岩组、荒岔沟岩组、大东岔岩组、双庙岩组和同心岩组,沉积时限为2 300～2 100Ma;后者为古元古代晚期内克拉通凹陷沉积,可进一步划分为林家沟岩组/达台山岩组、珍珠门岩组、花山岩组、临江岩组和大栗子岩组,沉积时限为1 900～1 800Ma.吉南新元古代地层的岩石地层学属性基本清楚,按新元古代三分的观点,其中细河群及其以下地层时代为青白口纪.浑江群时代为震旦纪,吉南地区缺失南华系.吉林省北部造山带中沿色洛河-海沟-青龙村-江域一线的元古宙地层事实上为不同时代、不同性质的构造岩片堆叠体,属于构造地层学范畴;具有层状地层特征的仅有敦化地区的塔东岩群、蛟河地区的新兴岩组、九台地区的机房沟岩群、辽源地区的西保安岩组以及安图地区的万宝岩组,时代可暂置于新元古代.

The Archeozoic metamorphic supracrustal rock series,Paleoproterozoic mid deep metamorphic volcanic-sedimentary rock series,superficial sedimentary rock series formed by the Neoproterozoic terrigenous clastic rock-carbonate rock in the southern part of Jilin Province and the Neoproterozoic metamorphic volcanic-sedimentary rock series in the orogenic belt of the northern part of Jilin Province can be discovered.Among them,the Archeozoic strata Longgang landmass is of a multiple matching of landmass character which can be divided into Longgang Group(Sidao Lazihe Formation and Yangjiadian Formation),Jiapigou Group(Sandaogou Formation,Laoniugou Group,Banshigou Group,Nangang Group(Ji`nan Formation,Guandi Formation) and Qingyuan Group,which stand for Baishan Town massif,Jiapigou Town massif,Banshigou massif,Helong massif and metamorphic supracrustal rock series of Qingyuan massif respectively,among them Longgang Group may belong to Mesoarchean era,the others belong to the Neoproterozoic.The Ji`an Group,Guanghua Group,of the Paleoproterozoic strata show the early rift sedimentation,which can be further divided into Mayihe Formation,Huangchagou Formation,Dadongcha Formation,Shuangmiao Formation and Tongxin Formation,the sedimentary age is 2 300～2 100Ma.The Laoling Group shows the late intracratonic depression sedimentation,which can be further divided into Linjiagou Formation/Dataishan Formation,Zhenzhumen Formation,Huashan Formation,LinjiangFormation and Dalizi Formation,the sedimentary age is 1 900～(1 800)Ma.The attribute of petrostratigraphy of Neoproterozoic strata in the southern part of Jilin Province is definite by and large,according to its viewpoint,Neoproterozoic strata are divided into three parts,the Xihe Group and its lower strata time belong to Qingbaikou period,the time of Hunjiang Group belongs to Sinian period,there is no Nanhua system in the southern part of Jilin Province.The fact is that Proterozoic strata along Seluohe-Haigou-Qinglongcun-Jiangyu,in the orogenic belt of the northern part of Jilin Province,are accumulative bodies of tectonite microlithon in different times and different characteristics,belonging to the extent of tecto-stratigraphy;among them only Tadong Group of Dunhua area,Xinxing Formation of Jiaohe area,Jifanggou Group of Jiutai area,Xibao`an Formation of Liaoyuan area and Wanbao Formation of Antu area show stratified characteristics,its time can be placed in the Neoproterozoic.