鸡西断陷盆地层序地层与聚煤作用研究
Study on sequence stratigraphy and coal accumulation function in Jixi Faulted Basin
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摘要: 为得到鸡西断陷盆地早白垩世层序地层地层格架中的展布特征,运用层序地层学有关理论和方法,对鸡西陆相断陷盆地早白垩世含煤岩系进行层序地层分析,并探讨了该断陷盆地的聚煤作用。研究结果表明:鸡西盆地早白垩世含煤地层共识别出3个层序边界,划分2个三级层序,分别对应于城子河组和穆棱组;煤层的聚集主要取决于可容空间变化速率和泥炭堆积速率,而在陆相断陷盆地中,控制两者变化速率的主要因素为构造活动和气候;鸡西断陷盆地早白垩世时期处于湖盆稳定发展向萎缩阶段过渡,湖盆稳定发展阶段基底速率变化缓慢、陆源碎屑供给相对较少,可容空间增加速率和泥炭堆积速率相对平衡,主要发育了三角洲平原相,有利于煤层的聚集;在三级层序中,湖侵体系域聚煤最好,其次为低位体系域和高位体系域。Abstract: In order to have the distribution features of the sequence stratigraphy framework in Early Cretaceous of Jixi Fault Basin,the related theory and method of the sequence stratigraphy was applied to the sequence stratigraphy analysis on the Early Cretaceous coal measures in Jixi Continental Fault Basin.The coal accumulation role of the Fault Basin was discussed.The study results showed that there were three sequence boundaries totally recognized in Early Cretaceous coal measures of Jixi Basin,two third grade sequences were divided and there were Chengzihe Formation and Muling Formation respectively.The seam accumulation mainly was subjected to the accommodation space variation rate and the peat accumulation rate.In the continental fault basin,the main factors to control the variation rate of the accommodation space and peat would be the tectonic activities and climate.Early Cretaceous period of Jixi faulted basin was in a stable development of a lake basin transited to a shrinking stage.In the stable development stage of the lake basin,the basement changing rate was gently,the terrigenous clastic supply was relatively less and the accommodation space increased rate and the peat accumulation rate were in a relevant balance.A delta plain was mainly developed and would be favorable to the seam accumulation.In the three grade sequences,a lake transgression system area would be best for the coal accumulation and the low level system area and the high level system area would be the second.