北京西山沿河城地区早白垩世火山—沉积盆地的充填过程及构造意义  

Early Cretaceous Volcano—Sedimentary Basin——Filling Process and Tectonic Implication in Yanhecheng Area,Western Hills of Beijing

作　　者：渠洪杰[1,2] 王猛[3] 余佳[2] 冯卉[2] 康艳丽[2] 陶涛[2] 宋立才 

机构地区：[1]北京探矿工程研究所,北京100083 [2]中国地质科学院地质力学研究所,北京100081 [3]中国五矿集团公司,北京100010

出　　处：《地质论评》2016年第6期1403-1418,共16页Geological Review

基　　金：国家自然科学青年基金项目(编号:41102057);中国地质调查项目(编号:1212011121095)联合资助~~

摘　　要：北京西山沿河城地区的火山—沉积盆地处于太行山与燕山构造带的交汇部位,主要保存了下白垩统东岭台组火山—沉积地层。沉积作用分析表明盆地内沉积相变显著,主体发育了冲积扇、辫状河流和湖泊相,并组成向上渐细的序列,其间具有发育的火山喷发熔岩相和火山碎屑流相。古水流和砾石成分统计表明,盆地发育初期物源主要来自于东部或北东方向的中元古界雾迷山组,之后沉积物主要来自于西部或西南部的元古界,并增加了同时期的火山岩砾石。盆地底部火山碎屑岩锆石U-Pb年龄指示盆地发育起始于140.7 Ma前后,并在132.24 Ma之后发生重大转折。结合区域地质演化、盆缘断层构造、沉积充填过程和东岭台组内正断层特征,认为盆地发育受控于北东走向沿河城断层的左行走滑应力场,以及由此所导致的北西向横岭—沿河口断层的伸展作用。该期左行走滑作用在华北东部晚中生代期间由挤压到伸展转换的过程里起到了重要的调整作用。Western Hills of Beijing locates in the intersection part of Taihang and Yanshan tectonic belts, there were a series of Early Cretaceous volcano—sedimentary basins in northwest of Western Hills of Beijing,and preserved a set of volcanic rocks and clastic rocks,named by the Donglingtai formation which can be divided into four sections.Basin fills consist predominantly of alluvial fan,braided river,lacustrine and volcaniclstic deposits. The series of alluvial fan conglomerate were preserved in the lower part of first and second section of Donglingtai formation,respectively.Braided river deposits composed mainly of the upper layers of the second section. Lacustrine facies developed in the Yanhecheng basin,and along two border faults,the Yanhecheng fault and the Hengling—Yanhekou fault.Paleocurrent and gravel composion stastistics indicate that the Proterozoic Wumishan formation northeast of basins provided most deposits at first,after that mainly from the west area of basins,and the same period of volcanic gravels.The pyroclastic rocks of the bottom of first section zircon U-Pb age revealed the initial and inverive time of basin as 140.7Ma and 132.24Ma,respectively.Based on the characteristic of Basin-margin structure,filling process,the normal fault in Donglingtai formation,and evolution of regional geology,the north-east direction of Yanhecheng fault is thought to have played a critical role by left-lateral transtension,and created extensional stress along the southwestern Hengling—Yanhekou fault.The left-lateral transtension during the early stage of early Cretaceous may has played an important role in adjustment from compression to extension in late Mesozoic in eastern of North China.

关 键 词：北京西山 沉积作用 物源 左行走滑伸展 早白垩世 

分 类 号：P534.53[天文地球—古生物学与地层学] P548[天文地球—地质学]