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Depositional characteristics and process of deep-water channel sedimentary system influenced by contour currents is a current hotspot and new scientific issue in the study of deposits resulted from interaction between contour currents and turbidity flows. Using root mean square (RMS) attribute, coherenceseismic attribute, time structure and stratal slice, we focus on depositional characteristics and process of the channel sedimentary system in Pliocene strata in the Beijiao Sag, Qiongdongnan Basin. The results show that the channel sedimentary systems are divided into the early and late channel sedimentary systems. The depositonal units of the early system include channel, flake-shaped and fan-shaped overbank deposits. The units of the late systems incorporate: channel and flank-shaped overbank deposits. Fan-shaped overbank deposits are only distributed on the right side of the bend of the channel. Flake-shaped overbank deposits are only located on the left side of the channel. The channels are persistently oblique to the strike of the slope and they are symmetrical and characterized by vertical aggradations. Combined with the development features of mounded drifts and moats over the Beijiao uplift, it is inferred that the geometry of the channel sedimentary systems are mainly controlled by depositional products of the interaction between turbidity flows and contour currents. Contour currents flow across channels, forcing the upper part (low velocity and low density) of turbidity flows to deflect towards the left (downstream) side of channels and then form overspill currents. The direction of overspills is the same to that of contour currents, in this case, generating wide flake-shaped overbank deposits extending for several kmlometers. In the bend of channels, the direction of overspill currents is in contrast to that of contour currents, blocking or confining the range of the overbank deposits and then creating fan-shaped overbank deposits. This result are consistent with the previous results of flume-tank experiment.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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