东海岛屿风尘沉积中的碳酸盐特征及地质意义

CONTENT OF CaCO₃ IN THE LOESS OF SHENGSI ISLANDS

摘要: 通过分析东海嵊泗列岛嵊山黄土、浪岗山黄土的CaCO₃特征,发现其含量极低,仅为0.1%左右,远低于内陆黄土,这是由于降水量大、剖面厚度小及周围多火山活动等因素共同作用的结果。按成因划分,嵊泗黄土中的CaCO₃属于后期淋溶残余型,不适于作为恢复当地古环境的替代指标。与基本在同一直线上的兰州、渭南、南京及嵊山等地黄土中的CaCO₃平均含量进行比较,发现其由西北向东南均匀递减,这是由于风尘黄土地层的淋滤作用和Ca (HCO₃)₂的淀积作用强度对降水量变化的响应速度不同的结果。

Abstract: We analyzed the content of CaCO₃ in the loess of Shengshan Island and Langgangshan Islands,and found the content is only about 0.1%, which is far below that in other loess sections.That should be caused by high precipitation,thin thickness of the section and lots of volcanic eruptions around. The CaCO₃ in the loess of Shengshan Island and Langgangshan Islands belongs to deuterogenic residual CaCO₃, and cannot be used to reflect paleoclimate. We contrast the content of CaCO₃ in the loess of Shengshan Island and Langgangshan Islands with other loess sections, and find the content of CaCO₃ in the loess is decreased equably, which should be the result of different velocity of eluviate and illuviate caused by precipitation changes.