论文部分内容阅读
对滦河三角洲南部孔深383m的MT04孔进行了详细的岩石磁学和古地磁研究,结果显示:1)孔深0~90m和244~383m沉积物携磁矿物主要为磁铁矿,90~244m沉积物携磁矿物主要为赤铁矿;2)基于208个样品(28个交变样品,180个热退样品)分离出的特征剩磁,建立了钻孔的磁性地层,并与标准极性年表相对比。结果显示,MT04孔记录了Mammoth负极性亚时(C2An.2r)至Brunhes正极性时(Cln)之间的沉积,钻孔M/B界限埋深122.4m,G/M界限埋深为327.2m,钻孔底部年龄约为3.2Ma,而钻孔上更新统底界埋深为83m。MT04孔包括3个沉积阶段:Ⅰ阶段为1.0~3.2Ma,沉积速率平均为92m/Ma,湖相地层为主,为构造稳定期,气候控制了MT04孔的沉积环境和速率;Ⅱ阶段为0.8~1.0Ma,为构造活动期,沉积物以细砂为主,且多为入湖河流和富有机质的粉砂;Ⅲ阶段为0~0.8Ma,构造和气候变化双重作用控制沉积过程,MIS 5阶段T3阶地形成之后河流下切,研究区沉积约30m厚连续砂层,且部分层位受海侵影响形成潮控河流;MIS 3阶段滦河东流并入青龙河入海,在此沉积约15m厚连续砂层;MIS 1阶段滦河摆动至此入海形成典型的两期沙坝-澙湖海岸。
The detailed magnetotectic and magnetotelluric studies of MT04 pore in the 383m deep hole of Luanhe delta in southern Luanhe delta show that: 1) the magnetite-bearing minerals in the depth of 0 ~ 90m and 244 ~ 383m are mainly magnetite, The 244m sediment-bearing magnetite is mainly hematite. 2) Based on the characteristic remanent magnetization of 208 samples (28 alternating samples and 180 thermal samples), a borehole magnetic stratum was established and compared with the standard pole Sexual chronology contrast. The results showed that MT04 well recorded the deposition of Mammoth negative polarity sub-phase (C2An.2r) to Brunhes positive polarity (Cln), the depth of drilling M / B boundary was 122.4m and the G / M boundary depth was 327.2m , The bottom of the borehole is about 3.2Ma at the bottom, while the buried depth of the bottom of the reefs on the borehole is 83m. MT04 pore consists of three depositional stages: Ⅰ stage is 1.0 ~ 3.2Ma, the average deposition rate is 92m / Ma, the lacustrine formation is the main, for the structural stability period, the climate controlled the depositing environment and the rate of MT04 hole; Ⅱ stage is 0.8 ~ 1.0Ma. During the tectonic activity period, the sediments are dominated by fine sand and mostly are inflow rivers and organic-rich silt. In the third stage, the sedimentary processes are controlled by tectonism and climate change. MIS 5 After the formation of stage T3, the river was undercut. In the study area, a continuous sand layer of about 30 m in thickness was deposited, and part of the horizon was affected by transgression to form a tidal stream. In MIS 3 stage, the Luanhe East stream merged into the Qinglong River and deposited about 15 m thick Sand; MIS 1 phase Luan River swing to this into the sea to form a typical two period of sand dam - Lake shore.