煤层在层序地层学划分对比中的意义——以准噶尔盆地白家海地区侏罗系为例

Significance of Coal Bed in Dividing and Correlating Sequence Stratigraphy——taking Jurassic Baijiahai Area in Junggar Basin as an example

煤层是层序格架内的标志性沉积物,对其发育规律的认识有助于层序地层学研究工作的开展。以准噶尔盆地东部白家海地区侏罗系为例,通过对古地貌、砂岩百分比及重矿物百分含量的分析,确定古物源的演化规律,再结合古气候、岩性、录井及基准面变化等资料,研究该地区煤层发育的控制因素。对该地区几个聚煤时期碎屑物质的供应程度、古植物、古气候、及湖平面(基准面)变化、古地貌格局,以及可容空间变化率与古气候变化的关系等进行综合研究,认为"有效"可容空间演化历史控制层序地层时空展布特征,是影响煤层在层序格架中展布规律的关键因素。该地区侏罗系煤层受沉积古地貌、碎屑供应程度及古气候等多种因素共同控制,并主要发育于基准面较长期稳定上升的阶段,与层序的时空演化存在着有机联系。

Coal bed,as a kind of benchmark substance,helps to research sequence stratigraphy.Taking Jurassic Baijiahai area in eastern Junggar Basin as an example,the evolution rule of the paleo-provenance was analyzed through the analysis on palaeogeomorphology,sandstone percentage and heavy mineral percentage content,and the controlling factors of the development of coal bed in the area was determined combined with paleoclimate,lithology,logging,base level change and other data.Comprehensive research was made on supply degree of clastic substance,palaeobotany,paleoclimate,change of lake level（or base level） and configuration of paleogeomorphy in the stages of the coal formation,as well as the relationship between change rate of ac commodation and the change of paleoclimate. It suggests that evolution history of ＂ effective ＂ accommodation controls the distribution of sequence stratigraphy,and it is the key factor controlling coal bed distribution in sequence framework.The Jurassic coal beds in this area were controlled by the palaeogeomorphology,supply degree of clastic substance,paleoclimate and other factors together.The coal beds developed in the stage of long-term stable rise of the base level and they have organic connection with temporal and spatial evolution of sequences.