吴悦,王东东,王海亮,等. 近海断陷盆地古近纪煤系沉积控煤作用与成煤模式−以山东黄县盆地为例[J]. 煤田地质与勘探,2023,51(4):23−36. DOI: 10.12363/issn.1001-1986.22.10.0794
引用本文: 吴悦,王东东,王海亮,等. 近海断陷盆地古近纪煤系沉积控煤作用与成煤模式−以山东黄县盆地为例[J]. 煤田地质与勘探,2023,51(4):23−36. DOI: 10.12363/issn.1001-1986.22.10.0794
WU Yue,WANG Dongdong,WANG Hailiang,et al. Sedimentary coal-controlling effect and coal-forming model of Paleogene coal measures in paralic faulted basin:A case study of Huangxian Basin, Shandong Province[J]. Coal Geology & Exploration,2023,51(4):23−36. DOI: 10.12363/issn.1001-1986.22.10.0794
Citation: WU Yue,WANG Dongdong,WANG Hailiang,et al. Sedimentary coal-controlling effect and coal-forming model of Paleogene coal measures in paralic faulted basin:A case study of Huangxian Basin, Shandong Province[J]. Coal Geology & Exploration,2023,51(4):23−36. DOI: 10.12363/issn.1001-1986.22.10.0794

近海断陷盆地古近纪煤系沉积控煤作用与成煤模式以山东黄县盆地为例

Sedimentary coal-controlling effect and coal-forming model of Paleogene coal measures in paralic faulted basin:A case study of Huangxian Basin, Shandong Province

  • 摘要: 我国海域区煤型油气资源量丰富,然而海域煤型烃源岩的研究程度却相对较低,严重制约了海域区煤型油气资源勘探。选取与海域区煤盆地成煤时代基本一致、地质条件相似、研究程度高的近海断陷含煤盆地——黄县盆地为例,开展沉积控煤作用与成煤模式研究。在充分吸取前人研究成果的基础上,精细重建了成煤期的古地理格局、演化及其沉积控煤作用。结果表明:(1) 黄县盆地古近纪煤系主要发育冲积扇、扇三角洲、辫状河三角洲和湖泊沉积,可以识别出2个三级层序。煤层主要发育在湖扩张体系域时期的辫状河三角洲、滨浅湖环境。(2) 综合恢复了涵盖古近系整个成煤过程的层序I湖扩张体系域和高水位体系域、层序II低水位体系域和湖扩张体系域的层序−古地理格局,并分析其沉积演化特征与沉积控煤作用;煤层主要发育在低水位体系域晚期−湖扩张体系域早期,湖平面缓慢上升的辫状河三角洲前部湖沼环境,并逐步向辫状河三角洲扩展;其次,煤层发育在湖扩张体系域的中晚期,湖平面频繁变浅−变深的湖沼−浅湖沉积环境。(3) 建立了古近纪近海断陷盆地2种典型的沉积成煤模式。一是滨浅湖湖沼−辫状河三角洲成煤模式,主要发育在低水位体系域晚期−湖扩张体系域早期湖水平面缓慢抬升的过程,煤层厚度较大但分布相对局限,如煤4、煤2。二是滨浅湖湖沼−浅湖成煤模式,主要发育在湖扩张体系域中−晚期湖平面下降−上升的过程中;湖平面升降频繁导致成煤环境频繁出现−消失,形成的煤层厚度较小但分布较广,如煤1、煤上1等。本研究阐明的近海断陷盆地煤层发育规律和建立的沉积成煤模式,将为海域区煤型烃源岩勘探提供一定的理论支持。

     

    Abstract: There are abundant coal-type oil and gas resources in Chinese sea area, but few researches have been conducted on the coal-type source rock, which seriously restricts the exploration of coal-type oil and gas resources in the sea area. Herein, this study on sedimentary coal-controlling effect and coal-forming model was carried out based on Huangxian Basin that is a paralic faulted basin with same coal-forming period, similar geological conditions and high degree of research for the coal basins in the sea area. Specifically, the pattern, evolution and sedimentary coal-controlling effect of paleogeography during the coal-forming period were reconstructed with full consideration to the previous research results. The results show that: (1) alluvial fan, fan delta, braided river delta and lacustrine deposit are mainly developed in the Paleogene coal measures in Huangxian Basin, where two third-order sequences can be identified. Definitely, the coal seam is mainly developed in the braided river delta and shore-shallow lacustrine environment during the lake expansion systems tract (EST). (2) The sequence-paleogeographic pattern of the EST and high-stand systems tract (HST) in sequence I, as well as the low-stand systems tract (LST) and EST in sequence II, covering the whole coal-forming process of Paleogene was comprehensively reconstructed. Meanwhile, the sedimentary evolution characteristics and sedimentary coal-controlling effect were analyzed. The coal seam is mainly developed in the late LST-early EST and the lacustrine bog environment in the front of braided river delta with the lake level rising slowly, and gradually expanded to the braided river delta. Besides, the coal seam is mainly developed in the middle and late EST, and the shallow lake sedimentary environment with the lake level frequently changing from shallow to deep. (3) Two typical sedimentary coal-forming models of Paleogene paralic faulted basins were established. Firstly, the coal-forming model of shore-shallow lacustrine bog braided river delta is mainly developed during the late LST to early EST when the lake level rose slowly. In this model, the coal seam thickness is relatively large but its distribution is relatively limited, such as coal 4 and coal 2. Secondly, the coal-forming model of shore-shallow lacustrine bog shore-shallow lacustrine is mainly developed during the descending and ascending of lake level in the mid-late EST. The frequent rise and fall of lake level lead to frequent appearance and disappearance of coal-forming environment, resulting in small thickness and wide distribution of coal seam, such as coal 1, upper coal 1, etc. Generally, the development law of coal seam and the sedimentary coal-forming model established in the paralic faulted basin illustrated in this study would provide some theoretical support for the exploration of coal-type source rocks in the sea area.

     

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