论文部分内容阅读
北部湾东北部GC19-28孔260BC~1480A.D.粘土矿物学的高分辨率(平均分辨率为15年)分析表明,该孔的粘土矿物主要由蒙脱石(50%~61%)组成,含中等含量的伊利石(13%~18%)、高岭石(13%~18%)和绿泥石(11%~16%),在该时间序列上蒙脱石与其他3种粘土矿物变化趋势基本相反。物源区分析显示,GC19-28孔粘土矿物中的蒙脱石主要由红河提供,伊利石、高岭石和绿泥石主要来源于珠江。该孔高岭石/蒙脱石比值可以反映华南珠江流域季风降雨变化,比值增加表明珠江流域降雨增强;反之亦然。研究结果发现,GC19-28孔的4种粘土矿物整体表现2个阶段性变化:1)260BC~1200A.D.,4种粘土矿物的相对含量基本保持不变,高岭石/蒙脱石比值同样保持不变;2)从1200~1480A.D.,蒙脱石相对含量逐渐降低,伊利石、高岭石和绿泥石相对含量逐渐增加,高岭石/蒙脱石比值开始增加。结合贵州董哥洞石笋、广东湖光岩、西沙东岛湖泊沉积物和西太平洋暖池区海表古温度等高分辨率地质记录,推断华南珠江流域由中世纪暖期向小冰期转换过程中,降雨逐渐增加。
The GC19-28 bore 260BC-1480A.D in northeastern Beibu Gulf. The high resolution (average resolution 15 years) analysis of clay minerals shows that the clay minerals in the bore are mainly composed of montmorillonite (50% -61%) (13% -18%), kaolinite (13% -18%) and chlorite (11% -16%) with medium content. In the time series, montmorillonite and other three kinds of clay The trend of mineral changes basically the opposite. Analysis of provenance area shows that the montmorillonite in GC19-28 clay minerals is mainly provided by Honghe, while illite, kaolinite and chlorite mainly come from the Pearl River. The ratio of kaolinite / montmorillonite in this hole can reflect the change of monsoon rainfall in the Pearl River Basin in South China. The increase of the ratio indicates that the rainfall in the Pearl River Basin is enhanced, and vice versa. The results show that the four clay minerals GC19-28 overall performance of two stages of changes: 1) 260BC ~ 1200A.D, the relative content of four clay minerals remained unchanged, the ratio of kaolinite / montmorillonite The same remained unchanged; 2) from 1200 ~ 1480A.D., the relative content of montmorillonite gradually decreased, the relative content of illite, kaolinite and chlorite gradually increased, and the ratio of kaolinite / montmorillonite began to increase. Based on the high-resolution geological records of stalagmite of Dongge Cave in Dongguo, Guangdong, Huguangyan in Guangdong, sediments in Xisha Island in the East China Sea, and the sea surface paleo-temperature in the western Pacific warm pool area, it is concluded that during the transition from the warm period of Middle Ages to the Little Ice Age, Rain gradually increased.