侯海海,李强强,邵龙义,等. 珲春盆地古近纪含煤地层层序–古地理与聚煤规律[J]. 煤田地质与勘探,2022,50(6):41−55. DOI: 10.12363/issn.1001-1986.21.12.0734
引用本文: 侯海海,李强强,邵龙义,等. 珲春盆地古近纪含煤地层层序–古地理与聚煤规律[J]. 煤田地质与勘探,2022,50(6):41−55. DOI: 10.12363/issn.1001-1986.21.12.0734
HOU Haihai,LI Qiangqiang,SHAO Longyi,et al. Sequence-paleogeography and coal accumulation of the Paleogene Hunchun Formation in the Hunchun Basin[J]. Coal Geology & Exploration,2022,50(6):41−55. DOI: 10.12363/issn.1001-1986.21.12.0734
Citation: HOU Haihai,LI Qiangqiang,SHAO Longyi,et al. Sequence-paleogeography and coal accumulation of the Paleogene Hunchun Formation in the Hunchun Basin[J]. Coal Geology & Exploration,2022,50(6):41−55. DOI: 10.12363/issn.1001-1986.21.12.0734

珲春盆地古近纪含煤地层层序–古地理与聚煤规律

Sequence-paleogeography and coal accumulation of the Paleogene Hunchun Formation in the Hunchun Basin

  • 摘要: 珲春盆地是吉林省重要聚煤盆地,分析古近纪珲春组的沉积古地理,总结其层序格架下聚煤规律,可以为研究区煤炭和煤层气资源的勘探规划提供理论依据。基于区域地质、钻孔岩心和测井资料,对珲春组岩相类型、沉积体系、层序–古地理和聚煤特征进行分析。结果表明,珲春组共发育砾岩、砂岩、粉砂岩、泥岩和可燃有机岩5类岩石类型和12种岩相类型。根据区域不整合面、河流下切谷冲刷面和沉积体系转换面等3类层序界面,将珲春组划分为3个三级层序,建立了珲春组等时地层格架。基于各三级层序内的地层厚度、砂岩厚度、砂泥比和煤层厚度分布,恢复了各层序岩相古地理,认为珲春组共发育冲积扇、辫状河、辫状河三角洲和湖泊4类沉积体系,具体包括12类沉积亚相和13类沉积微相,物源主要位于研究区的南北两侧。在各层序地层格架内,珲春盆地煤层展布具有明显规律性。层序Ⅰ—Ⅲ,聚煤作用先增强后减弱,厚煤层主要发育在湖侵体系域和高位体系域等碎屑沉积体系明显减弱时期。珲春组主要有3个聚煤中心,分别位于研究区西部八连城地区、南部板石地区和东部的54-9钻孔附近。聚煤中心和地层沉积中心有较好的对应关系,且两者从层序Ⅰ—Ⅲ呈现出由盆地西部向东部再向西部迁移的趋势,成煤古地理单元主要为扇端漫流沉积、辫状河河漫滩、辫状河三角洲平原分流间湾及湖泊滨湖亚相。

     

    Abstract: The Hunchun Basin is an important coal-bearing region in Jilin Province, northeastern China. The analysis of the sedimentary paleogeography of the Paleogene Hunchun Formation and coal-accumulation law in the sequence framework provides a theoretical basis for future coal and coalbed methane exploration. The lithofacies, sedimentary systems, sequence paleogeography, and coal accumulation characteristics were analyzed based on regional geology, drilling cores and well logging data. The results show five rock types, including gravel, sandstone, siltstone, mudstone, and combustible organic rock, and twelve lithofacies. The Hunchun Formation was divided into three third-order sequences by three sequence interfaces, including the regional unconformity surface, the river incised valley washed surface and the sedimentary system abrupt surface, and the isochronal stratigraphic framework of the Hunchun Formation was built. Three maps of lithofacies paleogeography were reconstructed according to the strata thickness, sandstone thickness, sand-mud ratio, and the distribution of coal seam thickness in each sequence. In the Hunchun Formation, four sedimentary systems (alluvial fan, braided river, braided river delta, and lacustrine), twelve sedimentary subfacies, and thirteen sedimentary microfacies were identified with provenances in the north and south sides of the study area. Within the stratigraphic framework of each sequence, there were laws for the coal seam distribution in the Hunchun Basin. From sequence Ⅰ to sequence Ⅲ, the coal accumulation first increased and then decreased. The thick coal seams were mainly developed in the period in which the clastic sedimentary system was weakened significantly, such as lacustrine transgressive system tracts and highstand system tracts. There are three coal-accumulation centers in the Hunchun Formation, located in Baliancheng, Banshi, and nearby 54-9 drilling well in the western, southern and eastern areas, respectively. There was a good corresponding relationship between the depositional center and the coal-accumulation center, and both of them were changed from the west to the east and then to the west again from sequence Ⅰ to sequence Ⅲ. The favorable paleogeographic units of coal accumulation were the sheet flow in the fan end, flood plain in the braided river, interdistributary bay in braided delta plain, and shore lacustrine.

     

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