Spatial configuration of sand and mud in the lacustrine nearshore sand bar deposits and its geological implications

SHANG Xiaofei,DUAN Taizhong,HOU Jiagen,LI Yan

Table 2 Different orders of interlayers in sand bar reservoirs and their depositional characteristics.

Configuration interface grade Configuration system from Miall Configuration element Genetic type of mud Lithology Combination pattern of sand and mud Interlayer type Occurrence 7 order 3 order Compound sand bar Fine grained deposits between compound sand bars Lacustrine mudstone, muddy siltstone and silty mudstone Thick mud Muddy interlayer Widespread, lenticular reservoirs interbedded with interlayers 8 order 4 order Individual bar Sand-mud interbedded beach between individual sand bars Muddy siltstone, silty mudstone and siltstone Thin sand and thin mud interbed pattern Muddy, calcareous, tight silt interlayers Scattered, strips parallel to shore- line locally Argillaceous sediments behind the bar Silty mudstone, mudstone and shale Thick-mud thick-sand pattern Muddy, calcareous, compact silt Locally continuous, with convex bottom and flat top on profile 9 order 5 order Accretionary body Fall-silt seams between accretions in individual bars Silty mudstone Thin-mud thick-sand pattern Muddy, compact silt Horizontal landward and tilting lakeward at a low angle