Cold event at 5 500 a BP recorded in mud sediments on the inner shelf of the East China Sea   总被引：2，自引：0，他引：2  

徐方建  李安春  胥可辉  李铁刚  陈世悦  万世明  刘建国 《中国海洋湖沼学报》2009,27(4):975-984

A 700-year record (1.0–1.5 a resolution) of the East Asian winter monsoon (EAWM), based on grain-size analysis and AMS¹⁴C dating of Core EC2005 from the inner-shelf mud wedge of the East China Sea (ECS), was compared with the Dongge stalagmite δ¹⁸O record during the mid-Holocene. The upper muddy section of Core EC2005 has been formed mainly by suspended sediments derived from the Changjiang (Yangtze) River mouth since 7.3 ka BP. High precipitation and a strengthened EAWM might have played key roles in the high sedimentation rate (1 324–1 986 cm/ka) between 5.9–5.2 ka BP. The EAWM strengthened when the Asian summer monsoon weakened, especially around 5 500 a BP, which corresponded to a worldwide cold event. The EAWM during the mid-Holocene shows statistically significant solar periodicities at 62 and 11 a. The 5 500 a BP cold event might be resulted from orbital forcing and changes in solar activity.  相似文献   

孟加拉湾中部沉积物地球化学特征及其古海洋学意义     

谭龙  刘建国  黄云  Md Hafijur Rahaman Khan  徐政  刘升发  石学法 《矿物岩石地球化学通报》2023,(4):786-795+683

本文通过分析柱状沉积物E87-32B孔的稀土元素组成特征，探讨该孔陆源沉积物的源区，并进一步判别其ΣREE含量变化的古环境意义。结果显示，E87-32B孔沉积物的ΣREE含量为150.2～180.2μg/g。在经上地壳稀土元素标准化后，沉积物的稀土元素配分模式具有明显的Eu负异常，这与恒河-布拉马普特拉河源区最为接近，证实研究区的沉积物主要来源于恒河-布拉马普特拉河。沉积物的ΣREE含量与(Gd/Lu)_UCC表明研究区存在少量印度半岛与伊洛瓦底江物质的输入。沉积物的ΣREE含量整体上表现出冰期-间冰期的变化特征。在冷期MIS 2阶段减弱的印度夏季风导致喜马拉雅系统降雨与侵蚀速率的降低，从而引起恒河-布拉马普特拉河源区的供给量减少，因此ΣREE含量处于低值区间，而在暖期MIS 1阶段则是与之相反的过程。  相似文献   

构造活跃区铁路隧道构造软岩大变形的总体特征和控制因素     

刘建国贾哲强王栋张广泽李天雨郭周富 《地质灾害与环境保护》2023,(3):43-48

西南复杂艰险山区等典型构造活跃区隧道围岩大变形问题突出，仍需进一步研究西南山区等构造活跃区铁路隧道大变形的控制因素。为此，本文以西南活跃区软岩大变形隧道为主要研究对象，对西南山区构造活跃区地质环境特征进行了系统梳理，总结了此区域内的拉林线江木拉隧道、丽香线中义隧道和成昆复线大坪山隧道等典型大变形隧道隧址区地质构造、地应力场和地层岩性的共性特征，综合分析构造软岩大变形的受控因素和总体特征，研究成果和结论可为西南山区铁路隧道大变形的机理认识和预测防控提供参考。  相似文献