黑龙江依兰盆地古近系煤与油页岩共生特点及层序地层格架

Paleogene Coal and Oil Shale Paragenetic Features and Sequence Stratigraphic Framework in Yilan Basin, Heilongjiang

黑龙江依兰盆地是我国典型的煤与油页岩共生盆地,通过对盆地古近系达连河组层序地层格架下煤与油页岩共生特征进行研究,识别出四种煤与油页岩共生组合,即煤层/油页岩/煤层组合、油页岩/煤层/油页岩组合、油页岩/其它沉积/煤层组合及油页岩/煤层组合。将达连河组划分为一个三级层序,其内部可以识别出4个体系域:低水位体系域(LST)沉积期,在地势低洼处发育厚度不大、分布局限的油页岩,向隆起区尖灭;湖扩张体系域(EST)沉积期,4种煤与油页岩共生组合均有发育;湖扩张体系域从早期到晚期、从滨湖到湖中心,共生组合中煤层厚度逐渐减小,油页岩厚度逐渐增大;早期高水位体系域(EHST)沉积期,主要发育厚度巨大、分布稳定的油页岩;晚期高水位体系域(LHST)不发育煤层和油页岩。可容空间增加速率与沉积物堆积速率的相关关系控制了煤、油页岩的发育和相互转换。

The Yilan Basin in Heilongjiang is a typical coal and oil shale paragenesis basin in China. Through study on coal and oil shale paragenetic features under the Paleogene Dalianhe Formation sequence stratigraphic framework, four coal and oil shale paragenet- ic associations identified, namely coal/oil shale/coal, oil shale/coal/oil shale, oil shale/other deposit/coal and oil shale/coal associations. Taking the Dalianhe Formation as a third order sequence, then 4 systems tracts can be identified： lowstand systems tract （LST） sedimen- tary stage, developed in topographically low-lying area with not thick and locally distributed oil shale and thinning out toward upwell- ing area; lake expansion systems tract （LEST） sedimentary stage, all four coal and oil shale paragenetic associations have been devel- oped, from early to late, lake shore to center, coal seam thickness in associations gradually decreasing, while oil shale thickness increas- ing; early highstand systems tract （EHST） sedimentary stage, mainly developed very thick and stable distributed oil shale; late high- stand systems tract （LHST） sedimentary stage, coal and oil shale all not developed. Correlationship between accommodation space in- creasing rate and sediment accumulation rate has controlled coal and oil shale development and interconversion.