昭通盆地茨营组沉积演化及聚煤规律研究

昭通盆地是云南省重要的褐煤产地。为了对区内褐煤资源进行客观评价,以野外地质调查和钻探成果为基础,通过对盆地的沉积相展布和区域地质背景分析,系统研究了盆地形成、演化过程和聚煤规律。研究结果表明:①盆地新近系茨营组广泛发育冲积扇-扇三角洲沉积体系、泥炭沼泽沉积体系和湖泊沉积体系;上新世早期盆地主体发育扇三角洲-半深湖-深湖沉积体系;上新世晚期发育泥炭沼泽-半深湖沉积体系;更新世早期发育半深湖-深湖沉积体系。②盆地经历了快速断陷期(上新世早期)、稳定坳陷期(上新世晚期)和稳定扩张期(更新世早期),形成了可采煤层M1、M2、M3,其中M1、M2煤层形成于湖平面相对上升泥炭沼泽,是盆地内分布最广泛的可采煤层,煤层M3主要分布于海子向斜。

A Study on Ciying Formation Sedimentary Evolution and Coal Accumulation Pattern in Zhaotong Basin

The Zhaotong Basin is a major brown coal producing area in the Yunnan Province. For an objective rating of lignite resources in the area, based on field geological investigation and drilling data, through sedimentary facies distribution in the basin and regional geological setting analysis, systematically studied basin genetic and evolutional process and coal accumulation pattern. The result has shown： （~） the Neogene Ciying Formation in the basin has widely developed alluvial fan-fan delta, peat bog and lacustrine sedimentary systems; and during early Pliocene in the principal part of the basin has developed fan delta-medium deep lacustrine-deep lacustrine sedimentary system; during late Pliocene developed peat bog-medium deep lacustrine sedimentary system; during early Pleistocene de- veloped medium deep lacustrine-deep lacustrine sedimentary system. （~） the basin has experienced rapid rift faulting （early Pliocene）, steady depressing （late Pliocene） and steady expanding （early Pleistocene） stages, and formed mineable coal seams Ml, M2 and M3, in which, the former two were formed in lake level relatively rising peat bog, thus widespread mineable coal seams in the basin, while the M3 mainly distributed in the Haizi syncline.