鸡西盆地早白垩世城子河组和穆棱组物源分析

充分利用研究区的野外露头，特别是露头所显示的砾石排列方向和各种层理构造、地震资料、岩芯重矿物资料，系统分析了能够指示物源方向的4种参数-古水流方向，地震反射特征、重矿物稳定系数及组合分异特征、鸡西盆地早白垩世沉积特征，结果表明，这4种参数的匹配情况良好，总体显示城子河组时期盆地大致存在西部和东南部两个方向的物源，其中西部物源为主要物源区，分别从西北、西部以及西南3个方向供给盆地沉积物，东南部物源区为次要物源区，影响范围较小；穆棱组时期基本继承了城子河组时期的物源体系，只是源区相对后退，反映出从城子河组到穆棱组为水进和湖盆范围变大的过程，东南部物源的影响范围较城子河组时期变大。利用重矿物组合特征进行源区对比，认为盆地西部物源区为小兴安岭-张广才岭造山带，盆地东南部物源来自延吉褶皱带。

Provenance Analysis of Chengzihe and Muling Formation in Jixi Basin,Northeastern China

The field outcrops,especially the arraying direction of gravel and various bedding structures revealed by the outcrops,seismic data,core and heavy mineral data have been fully used to analyze the four key parameters that indicate the paleo-provenance direction,which include paleocurrent directions,structural features of seismic reflection,stability coefficient,differentiation characteristics of heavy mineral assemblage and the sedimentary characteristics of Jixi basin.Comprehensive studies show that the four parameters match well.There were mainly two provenances located in the west and southeast of the basin,respectively,in Chengzihe Formation.The west provenance was the main one,which provided sediments from the northwest,west and southwest to Jixi basin,and gradually headed east while divided into two branches at Hengshan uplift,entered the south and north part of the basin,respectively.After analyzing depositional system of heavy minerals and comparing the types of circumbasin parent rock,west provenance was thought to be primarily from the orogenic belt of Xiaoxingan-Zhangguangcai Range.Progradation configuration in the seismic profiles pointed out that upon the southeast of the basin there existed another subordinate provenance with less influence,which was considered to be the secondary provenance.During the period of Muling Formation,the paleocurrent characteristics revealed that the main traits formed in Chengzihe Formation were mostly inherited,i.e.the basin still had two separate provenances,but the provenances relatively retreated,showing transgression from Chengzihe to Muling Formation,meanwhile,the range of the lake basin became larger.The southwest provenance had a bigger impact area compared with Chengzihe Formation.The features of heavy mineral assemblage reflected that the types of mother rock from the west part of the basin were consistent with orogenic belt of Xiaoxingan-Zhangguangcai Range,which indicated that the west provenance mainly came from the aforementioned orogenic belt,while the mother rock types from southeast site were consistent with Yanji fold belt,illustrating that southeast provenance mainly came from it,gradually augmented its influence on development of Jixi basin from Chengzihe Formation to Muling Formation.