Depositional Environments of the Shitouhezi Formation and Its Characteristics of the Episodic Coal Accumulation, Upper Jurassic Hegang Basin, Heilongjiang Province
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摘要: 鹤岗盆地是一中—新生代内陆盆地，主要含煤地层上侏罗统石头河子组是一套非海相含煤地层，充填于盆地底部，自下而上可划分为三个岩性段，五个亚段和２６个含煤旋回。底部第一亚段沉积期以冲积扇、辫状河环境为主；第二亚段以河流环境为主；第三亚段以河流—三角洲—湖泊环境为主；第四亚段演化为河流环境；第五亚段则以河流、冲积扇环境为主。垂向上五个亚段对应于盆地的填平补齐—扩张—稳定沉降—差异沉降—收缩五个演化阶段。富煤带位于同沉积中心的侧翼，一般含砂率６０%～７０%的区域含煤性最好。含煤旋回受控于盆地周期性地快—慢沉降，聚煤作用发育于每期幕式沉降的缓慢稳定沉降阶段。厚—特厚煤层都与湖泊三角洲冲积平原大面积沼泽化有关。Abstract: The Shitouhezi Formation is a set of non-marine coal-bearing strata, filled in the lower part of theMesozoic- Cenozoic interior basin of Hegang. The strata can be divided into three lithological membersincluding five submembers and 26 small cycles from bottom to the upper part. The first submember wasmainly marked by the alluvial fan and braided stream environments; the second submember the fluvial;the third submemeber the fluvial- delta- lacustrine; the 4th the fluvial again; and the 5th the fluvial andalluvial fan. Vertically, the five submembers respond to the five developing bhases which filled the lowerareas for horizontal ground of the basin- expanding- subsiding stably- subsiding differently- contract-ing of the basin. Richer coal- bearing areas are Locatek to the flank of syndepositional anticline bulge.Coal accumulation was controlled mainly by the periodic fast and slow subsiding of the basin. Coal accu-mulation occurred at each slower and more stable subsiding phase of the episodic subsidence. The excep-tionally thick coal beds are related to the largest swamped deltaic plain.
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[1] Andrew D Miall Analysis of Fluvial Depositional systems,1981, 23 ～ 32. [2] Allen J R L. Fining upward cycles in alluvial succession, Liv er-pool Manchester Geol. Jour, 4, 1965, 229 ～ 246. [3] Yang Zirong et al. The Lake Sedimentation of the ShitouheziFormation, Late Jurassic, Hegang district. Heilong jiangProvince, 1988, 8. IAS, International Symposium of Sedimen-tolog y Related to Mineral Deposits, 327. [4] 马杏垣,刘和甫,王维襄等. 中国东部中、新生代裂陷作用和伸展构造. 地质学报, 1983, 1: 11 ～ 21. -
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