山东广饶地区晚更新世以来沉积演化与古气候变迁

受晚更新世以来海侵影响,渤海西南内陆第四系浅层经历了复杂的海陆交替演化。利用4口钻孔取芯井和88口静力触探井资料,采用现代测试技术和地层对比的方法对渤海西南内陆广饶地区第四系浅层进行沉积学综合研究。广饶地区地表以下30 m内,南部以风成黄土沉积为主,北部自上而下发育两期海相层,在研究区称为第一、第二海侵层,分别是10~4 ka B.P.的黄骅海侵层和40~28 ka B.P.的献县海侵层。黄土沉积于晚更新世玉木冰期,在研究区南部以17 m为界划分为大站组和羊栏河组(未见底)。晚更新世以来发生两期海侵事件(黄骅海侵、献县海侵),在海侵范围最大时到达广饶地区,先后对冰期沉积黄土层侵蚀改造,形成了“上超型海蚀黄土”的海侵演化模式。根据海侵与黄土沉积演化所对应的古气候变迁,将研究区晚更新世以来气候演变划分为6个期次:干冷期、温暖湿润期、干冷偏凉期、温暖期、潮湿湿润期和现代气候期,对应不同的沉积演化特征。

Depositional Evolution and Paleoclimate Changes Since Late Pleistocene in Guangrao Area,Shandong Province

Influenced by transgressions, the shallow strata of Quaternary has a complicated sedimentary evolution in Guangrao area, the inland of Southwest Bohai Sea since Late Pleistocene. Below the surface of 30 meters, it mainly deposits loess in the south of the area, while in the north of the area, it mainly deposits two marine layers, which were respectively named the first transgression layer and the second transgression layer. The first transgression layer is Huanghua transgression layer of 10~4 ka B.P., while the second transgression layer is Xianxian transgression layer of 40~28 ka B.P. According to 4 drilling coring Wells and 88 static sounding wells studied the transgression evolution and loess of the area by using modern test methods (particle size analysis, heavy mineral analysis, 14C dating, geochemical tests) and stratigraphic correlation. The loess layer deposited in late Pleistocene, and can be divided into Dazhan formation and Yanglanhe formation in the south of area on the depth boundary of 17 meters. It had two transgression events (Huanghua transgression and Xianxian transgression) since late Pleistocene and came to the area in the maximum transgression time. Because of the erosion and modification of the two transgressive events, it had formed the transgressive evolution model of "transgression overlap the loess". According to the paleoclimate change which math to transgression and loess deposition evolution, climate change of the area can be divided into six periods since Late Pleistocene, including cold dry climate, warm humid climate, cold dry but slants cool climate, warm climate, moist climate and modern climate. Different type of climate corresponds to different feature of sedimentary evolution.