铁法盆地含煤沉积旋回的构造控制作用

The tectonic controlling action on coal-bearing sedimentary cycle of Tiefa basin

  • 摘要: 为探索铁法盆地含煤沉积旋回的成因,在应用沉积相分析方法揭示该盆地含煤沉积旋回特征的基础上,依据盆缘断裂活动引起可容空间的变化,进而控制沉积物体积分配、沉积相类型及其空间配置的原理,对其含煤沉积旋回的构造控制作用进行了深入研究。分析认为,在盆缘断裂活动导致可容空间减小和沉积充填速率较高的条件下,形成了盆缘断裂内侧冲积扇相及扇前河流相,并由后者构成含煤沉积旋回单元的主体;在盆缘断裂活动使得盆缘地带可容空间与沉积物体积相匹配的条件下,形成盆缘断裂内侧冲积扇后,很少有较粗碎屑向更远处进积,扇前大面积泥炭沼泽化形成了含煤沉积旋回单元的顶部煤层。上述两种情况周期性交替形成了铁法盆地的含煤沉积旋回。

     

    Abstract: In order to study the coal-bearing sedimentary cycle's origin of Tiefa basin, the authors have made further researches on the tectonic controlling action on coal-bearing sedimentary cycle.The above-mentioned researches are based on the reveal of the coal-bearing sedimentary cycle's characteristics by using the sedimentary facies analysis, and aslo on the theory that the activity of basin edge fault can cause the accommodation spatial change which can control the sediment volume partition, the types and spatial allocation of sedimentary facies.According to the above researches, the author gets the following understanding.The first understanding is that under the condition of the accommodation spatial decreasing and the higher depositional filling rate which is caused by the activity of basin edge fault, the interior of basin edge fault alluvial facies and the anterior fan fluvial facies are formed, meanwhile, the latter composes the main body of coal-bearing sedimentary cycle.The another understanding is that under the condition of the matching basin edge zone's accommodation space and sediment volume which is caused by the activity of basin edge fault, after the interior of basin edge fault alluvial fan is formed, few coarse clastic rocks can be moved further, and the large peat swamp gasification area at the anterior part of alluvial fan forms the upper coal seam of coal-bearing sedimentary cycle.The alternation of two kinds of above-mentioned situations forms the coal-bearing sedimentary cycle of Tiefa basin.

     

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