聚煤盆地中的水下重力流沉积

THE SUBAQUEOUS GRAVITY FLOW DEPOSITS IN COALFORMING BASINS

我国北方中生代聚煤盆地中一种特殊的粗粒碎屑沉积物不仅其各种成因单位可与Bouma层序对比,而且在砂体几何形态、规模、内部沉积构成和古流型式等方面也具有特色。对其进行沉积过程分析表明,每个成因单位代表一次水下重力流事件的沉积演化过程,与其共生的细碎屑沉积物多数形成于浅水湖泊环境。它们自成沉积体系,可能是近岸水下重力流扇或三角洲体系的水下部分。

Some characteristic coarse-grained clastic sedimentary sequences in Mesozoic coal- forming basins of northern China, not only, consist of multyple genetic units and each unit can be compared with Bouma sequence, but also they have typical characters of the geometry solid, spatial scale, internal depositional architecture and paleocurrent direction of the sedimentary association. The genetic unit reflects a depositional evolution process of subaqueous gravity flow event. But, their associated finegrained sediments are recognized as being formed in The shallow lake. Consequently, these sequences may be interpreted as products of shallow water subaqueous gravity flow.They may constitute special depositional system,for example, subaqueous fan of the gravity flow, fan-delta system.