康滇古陆西侧黑泥哨组沉积特征与暗色泥页岩分布

Sedimentary characteristics and distribution of dark mud shale in the Heinishao Formation on the west side of the Kang-Dian Paleocontinent

晚二叠世康滇古陆东西两侧均发育暗色泥页岩,沉积充填差异性明显。康滇古陆东侧宣威组(龙潭组)研究程度高,西侧黑泥哨组研究程度低,沉积环境和暗色泥页岩展布规律不清。通过对康滇古陆西侧盐源小高山、甲米、宁蒗西漂落、宜底黑泥哨组沉积充填序列和沉积环境分析,总结研究区沉积展布特征和暗色泥页岩分布规律,对大凉山地区页岩气勘探具有一定的参考意义。研究结果显示康滇古陆西侧自东向西沉积环境差异明显。黑泥哨组一段自西向东玄武岩层段减少,沉积时限西部早于东部。黑泥哨组二段沉积环境自东向西呈古陆—沼泽—潮坪—碳酸盐岩台地展布。黑泥哨组三段沉积环境自东向西呈三角洲—沼泽—潮坪—碳酸盐岩台地展布。暗色泥页岩主要分布在黑泥哨组二段和三段沼泽沉积环境中,平面上以小高山—西漂落地区较为发育,累计厚度20~30 m,具有较好的页岩气资源潜力。

Dark mud shales are developed on both the east and west sides of the Late Permian Kang-Dian ancient continent,with obvious differences in the sedimentary filling.The Xuanwei Formation(Longtan Formation)on the east side of the Kang-Dian ancient land is highly studied,while the Heinishao Formation on the west side is poorly studied.The depositional environment and the spreading pattern of the dark mud shale are unclear.By analyzing the sedimentary filling sequences and sedimentary environment of the Yanyuan Xiaogaoshan,Jiami,Ninglangxipiaoluo,and Yidi Heinishao Formations on the west side of the Kang-Dian ancient continent,we summarized the sedimentary spreading characteristics and the distribution pattern of dark mud shale in the study area,which has certain reference significance for shale gas exploration in the Daliangshan area.The results show that the sedimentary environment varies significantly from east to west on the western side of the Kang-Dian ancient continent.The basalt intervals of the first member of the Heinishao Formation decrease from west to east and the deposition time in the west is earlier than that in the east.The depositional environment of the second member of the Heinishao Formation shows a paleoland-swamp-tidal platform-carbonate terrace from east to west.The depositional environment of the third member of the Heinishao Formation is a deltaic-swampy-tidal platform-carbonate terrace from east to west.The dark mud shale is mainly distributed in the swamp sedimentary environment of the second and third members of the Heinishao Formation.On the plane,it is more developed in the Xiaogaoshan-Xipiaoluo area,with a cumulative thickness of 20 m to 30 m,and has good shale gas resource potential.