永城煤田二叠纪网状河流沉积体系

The anastomosed fluvial depositional systems in the Permian coal measures of the Yongcheng coalfield, Henan

关键词:  网状河  同沉积构造  永城煤田

Key words:  anastomosed stream  synsedimentary structure  Yongcheng coalfield

摘要:

永城煤田二叠系三、四煤组地层中,沉积相的空间配置、砂体特点等均显示出网状河流沉积体系的特征。这里的网状河流体系是在盆地整体沉降的背景中,在地形平坦、坡降低的三角洲平原上,受同沉积构造控制发育起来的。同沉积断裂和坳陷活动创造了长期相对低洼、可供河道发育的地形条件,加上繁茂的植被、沉降速度与补偿速度大体均衡、突发性海侵等因素的共同影响,网状水道得以较长时期地稳定发育。

Abstract:

In the third and fourth coal measures of the Permian strata in the Yongcheng coalfield, Henan, the spatial distribution of sedimentary facies,the features of channel-fill sandstones and other evidences have reflected the characteristics of anastomosed fluvial depositional systems, which are developed on the deltaic plain with flat topography and lower gradients against a background of basin subsidence,and governed by synsedimentary structures. The synsedmentary faulting and downwarping have created the permanent low-lying topographic conditions for the long-term and steady development of the anastomosed channels. Furthermore, the luxuriant vegetation,approximate balance between tectonic settling velocity and compensating velocity, and abrupt marine invasion also allow for the long-term and steady development of the above-mentioned channels.