辽宁兴城地区中元古界长城系大红峪组石英砂岩质砾岩古沉积环境研究  

STUDY ON PALEO-SEDIMENTARY ENVIRONMENT OF DAHONGYU FORMATION SANDSTONE CONGLOMERATE OF CHANGCHENG SYSTEM OF MESOPROTEROZOIC IN XINGCHENG AREA,LIAONING PROVINCE

作　　者：杨明春[1,2] 郑常青[1] 张梅生[1] 张扬[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061 [2]北京大学地球与空间科学学院,北京100871

出　　处：《矿物岩石》2012年第3期103-109,共7页Mineralogy and Petrology

基　　金：国土资源部公益性行业科研专项(201011083)

摘　　要：通过对辽宁兴城地区中元古界长城系大红峪组底部的石英砂岩质砾岩的野外调研、砾石颗粒统计分析,在显微镜下分别对砾石的砂岩和填隙物的砂岩进行了岩相学研究、粒度统计分析等研究工作,结果显示砾石粒径大小为5mm～420mm,组成砾石的砂岩主要为细粒砂岩和粉砂岩,其中石英碎屑颗粒以跳跃方式搬运为主;填隙物砂岩的石英碎屑颗粒包括悬浮、跳跃、滚动形式搬运的3个次总体,其概率累积曲线研究显示代表性填隙物砂岩的各项参数为:平均粒径Mz=2.3、标准偏差σ1=0.83、偏度Sk1=-0.06、尖度KG=1.025、粒度参数Y=-5.585。因此认为:构成砾石的石英砂岩其沉积环境为滨浅海环境中的前滨与后滨亚相;填隙物的石英砂岩形成于滨岸带,属无障壁海岸相中的海岸沙丘亚相沉积;石英砂岩质砾岩的形成环境为冀鲁古陆边缘与胶辽边缘海交界处。此砾岩层的出现证实本区在大红峪早期发生过一次构造抬升。Mesoproterozoic sandstone conglomerates distributed on the bottom of Dahongyu For- mation,Changcheng System in Xingcheng area have not been discovered in Dahongyu Formation in other areas of North China craton. The sandstone conglomerate is investigated in the field,and the size of gravels are measured and analyzed,and the fillings of sandstone are studied under mi-croscope. Statistic results show that the size of gravel in conglomerate ranges from 5 mm to 420 mm,and the sandstones in the gravels are mainly fine-grained sandstone and siltstone. Among them,quartz clastic particles were transported in a jump way; and those quartz particles in the fill-ings of sandstone can be further classified as three sub-types which were transported in suspen-sion,jumping and rolling ways,respectively. Their probability accumulating curves show that the parameters for the representative fillings of sandstone are Mz=2.3,σ1 = 0.83, Skl=0.06, KG=1. 025,and Y=-5. 585. On the basis of above research results,it is concluded that those grav-els composed of sandstone may be formed in foreshore and backshore sub-facies in a shore sedi-mentary environment, those fillings also composed of sandstone may be formed in coastal dune sub-facies of no barrier ripe facies in a coastal area,and those sandstone conglomerates were likely formed at the junction of Ji-Lu paleo-continental margin and Jiao-Liao marginal sea. It is suggest that the studied area has likely developed tempestite-like sedimentary event in response to Xingcheng Movement, forming the Dahongyu Formation strata. This study has an important im-plication on the formation and evolution of the Mesoproterozoic Yanshan Rift Trough.

关 键 词：长城系 大红峪组 石英砂岩质砾岩 古沉积环境 辽宁兴城 

分 类 号：TE121.31[石油与天然气工程—油气勘探]