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众多钻孔揭示,苏北滨海平原在冰后期泥质沉积区中存在一个以东台为顶点,呈扇形展开,面积约3000km~2的沙质沉积区,颇类似现今以掠港为顶点的海域辐射沙洲分布之势。沙体西薄东厚,最厚处达30余米。沙层中发育泥质条带、脉状层理、双向交错层理等潮汐沉积构造,并具有与海域辐射沙洲类似的粒度和矿物特征,证明该沙体为潮流成因。苏北海域辐射沙洲形成于辐聚辐散潮流场,陆区沙体是否也形成于辐聚辐散潮流场?这是个尚未解决的重要问题。近年来在该沙质沉积区已相继打了多口全取芯浅钻,本文选择其中南(丁河孔)、北(东套孔)两口钻孔岩芯(图1)作了沉积磁组构和剩磁测试,旨在揭示该区古水流方向,探讨沙体沉积时的古潮流分布状况。
Numerous boreholes reveal that there is a sand depositional area in the northern coastal plains in the sedimentary area of the late glacial period with the eastern part as the summit, fan-shaped area of about 3000km ~ 2, which is quite similar to the sea area radiation Sandbar distribution trend. Thin sand body thin east, the thickest at 30 meters. Sedimentary structures such as argillaceous zone, vein layer and two-way cross bedding are developed in the sand layer, which have the same grain size and mineralogical characteristics as the radiation sandbar in the sea area, which proves that the sand body is the cause of the tidal current. The radiant sandbanks in the northern Jiangsu are formed in the convergent divergent tidal flow field, and are the continental sand bodies also formed in the converging divergent tidal current? This is an unsolved problem. In recent years, many sand cores have been drilled in the sandy sedimentary area. In this paper, two core cores (Dinghe hole) and North (East sleeve hole) Structure and residual magnetism test, aimed to reveal the direction of paleocurrents in this area and to explore the distribution of ancient tidal currents when sand bodies are deposited.