黔西北晚二叠世含煤岩系高分辨率层序地层与聚煤模式研究

【作者】 陈朝玉；

【导师】 黄文辉；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2011， 博士

【摘要】 本研究针对黔西北晚二叠世龙潭组含煤岩系进行研究,在利用黔西北丰富的测井、岩芯数据等资料的基础上结合沉积学及高分辨层序地层学基本理论对黔西北晚二叠世含煤岩系进行深入剖析,并建立起了黔西北晚二叠世含煤岩系的等时层序地层格架。最后在等时地层格架下探讨了黔西北晚二叠世的聚煤模式。认为黔西北聚煤受控于地体旋转与海平面升降叠加引起的聚煤环境的非均一性变化。(1)依据晚二叠世含煤岩系岩芯和测井曲线所反映出来的沉积旋回性特点对晚二叠世含煤岩系共识别出3个三级复合层序。从重点钻孔剖面的解析及等时地层格架下的连井沉积相所反映出研究区的沉积环境及其在垂向上组合特征的综合分析中,归纳出研究区东部复合层序Ⅰ主要为碳酸盐台地沉积,以西为障壁潟湖、上三角洲沉积组合。复合层序Ⅱ在研究区东部继续发育碳酸岩盐沉积,以西则发育下三角洲沉积。复合层序Ⅲ在研究区以东碳酸盐岩沉积范围扩大,以西的障壁-潟湖的沉积范围缩小,而发育局限潮下沉积。(2)黔西北晚二叠世沉积环境主要为滨外碳酸盐台地沉积体系、障壁型碎屑岸线沉积体系、三角洲沉积体系及曲流河—湖泊沉积体系。其富煤带的形成与分布直接受控于古地理环境,富煤带与三角洲沉积组合关系最为密切。其次为障壁型碎屑岸线沉积组合。(3)研究区晚二叠世含煤岩系的形成经历了龙潭期—长兴期持续海进的过程。总体来说,在复合层序Ⅰ沉积阶段,聚煤中心在南部水城一带;在复合层序Ⅱ沉积阶段,聚煤中心则沿北东方向北迁移至金沙仁怀;在复合层序Ⅲ沉积阶段,由于陆地顺时针方向的旋转下切幅度偏大,研究区金沙、仁怀、桐梓等地区为碳酸岩盐台地沉积环境,使得聚煤中心发生向南的回迁。(4)聚煤环境的变迁及聚煤中心迁移的动力机制,在很大程度上认为与研究区陆地在晚二叠世发生的顺时针方向的旋转运动叠加相对海平面的变化引起的可容纳空间的非均一性变化有关,并在旋转旋回沉积的作用下发生聚煤中心的逆时针方向的迁移。旋转旋回沉积也能较好解释邵龙义教授提出的幕式聚煤中一次聚煤可以横跨不同的相区甚至不同的聚煤盆地的聚煤模式。更多还原

【Abstract】 In this paper, Northwestern Late Permian Longtan Formation coal-bearing rocks have been studied,Extensive use of logging in Northwestern, core data and other data and the sedimentology and high resolution sequence stratigraphy of basic theory, Northwestern Late Permian Coal Measures sequence boundary has been divided,And establish the Late Permian in northwest Guizhou Coal Measures sequence stratigraphic framework. Finally, the next isochronous stratigraphic framework of the Late Permian in northwest Guizhou coal accumulation mode. Coal center that was controlled by the migration of the rotation caused by plate rotation cycle deposition mechanism.(1)Through the Late Permian coal-bearing rocks of the core and logging the sedimentary cyclicity reflected characteristics of the Late Permian coal-bearing rock strata to identify a total of three three composite sequences. Single well and connected well on the comparative analysis,In the study area east of the main composite sequence carbonate platform depositsⅠ, west of the barrier lagoon, on the delta deposit portfolio. Composite SequenceⅡcontinue to develop in the study area east of Brush salt deposits, west of the delta deposits under development. Composite SequenceⅢin the study area east of the carbonate rocks extend to the west of the deposition of narrow barrier lagoon, while the development of limited tidal deposition.(2)Northwestern Late Permian sedimentary environment is primarily outside the carbonate platform depositional system of coast, barrier shoreline clastic depositional system, delta system and the meandering river lake sedimentary system.The Late Permian coal-rich belt directly controlled by the formation and distribution of ancient geography, the rich deposits of coal with a combination with Delta most closely. Followed by the combination of barrier shoreline deposits(3) In the study area of the Late Permian coal-bearing rocks of the formation. Overall,The whole sequence in the composite order phaseⅠcoal deposits in the southern center of Liupanshui area, and deposited in the composite sequenceⅡstage moved to the Sands, Renhuai,Ⅲsequence deposited in the composite stage, the clockwise rotation of the land makes the polymer Central place of coal to move back south.(4) Changes in the environment coal and coal center migration dynamic mechanism that is largely the study area and land occur in the Late Permian clockwise rotation of the related,Deposition in the rotation cycle of coal under the action of the migration of the center counter clockwise. Episodic coal accumulation can be well explained with a rotating cycle of deposition更多还原