The Sedimentary Records And Environmental Analysis Of ZK1,ZK3,ZK5 Drilling Cores In Latter-day Yellow River Delta Wetland

To study vertical deposited characteristic as well as the evolutionary law of nich in the wetland of Yellow River Delta, the data of three drillings cores in this area was collected. The time diversion of the five drilling cores was carried out, and historical data of Yellow River variance in Yellow River delta, the distributing of river road and inartificial bank, time of artificial buildings, sequential topographic map, variational trait of coast line and river, the investigation of field profile together with the age of sediments protruding through the soil level.,; the grain-size classification, mineral composition in these five boreholes were tested. The determination and comparison of foraminifera in ZK1, ZK3 and ZK5 were conducted.The analysis of standard deviation value vs. grain-size classes indicated that the composition of grain grade ranged from 3.875Фto 4Фor upward 10.125Ф, which was sensitive to the varying of sedimentary environment. The former was unanimous wih the river deposit and the latter was identical with flood plain deposit. In the light of the characteristics of foraminifera abundance and population in vertical direction from ZK1, ZK3 and ZK5, their evolutive environment of sendimentation can be divided into three stages: super-layer representing adlittoral shore environment, middle-layer representing the period of continental reinforcing under freshwater controlling, under-layer representing shallow sea environment whose salty approach natural sea.Through the analysis of mineral composition content in the ZK1 holes, It was found that high element content left in the sediment which was developed during the period of prodelta deposition since 1855 was mainly caused by the reassignment of bedload and series of environmental geological problems resulting from course changing, burst and the transformation of coastline. The source of the mineral composition l from the holes was possibly similar with each other.The content of illite with a little chlorite in ZK1 was relatively high, compared with kaolinite which could be neglected. It was supposed that the area sufferred from long-term dry and cold climate which was controlled by geological background, biological features as well as water dynamics.