黏土矿物古气候意义研究的现状与展望

A Review on Paleoclimate Interpretation of Clay Minerals

系统地分析了利用海洋沉积物、古土壤、湖盆沉积物中黏土矿物进行古气候环境研究的现状、存在问题和发展趋势。海洋沉积物的物源范围广,影响因素复杂,其中的碎屑黏土矿物所指示的古气候参数只能用于解释母源区的气候变化,而只有自生黏土矿物才能指示沉积区的气候;古土壤形成于特定的地质背景条件下,尤其是发育于火山物质母岩之上的风化自生黏土矿物,可以准确地指示该区的古气候条件;湖盆沉积物的物源范围小,沉积物中的黏土矿物可以更有效地运用于古气候环境的分析。对于沉积物中黏土矿物来源的分析,可以借助晶体中cv空位和tv空位的精细结构特征进行判断;在风化改造的红土剖面研究中,因强烈的化学风化、淋滤和迁移,黏土矿物方法具有独特的优势。风化过程中形成的一些亚种或过渡性黏土矿物,以及同生沉积过程中形成的黏土矿物,对气候环境的变化更加敏感,应加强这方面的研究。此外,在造山带的气候环境演化研究中,自生黏土矿物稳定同位素可以更可靠地指示气候环境的变化。

This paper summarizes the paleoclimate interpretation of clay minerals from marine sediments, palaeosols, lacustrine or basin deposits, and analyzes its difficulties and promising aspects. As marine sediments are derived from a variety of sources and their clay mineral components could be affected by complicated factors, the index for the paleoclimate illustrated by detrital clays can only be used for the interpretation of the paleoclimate conditions of the source area. While only the authigenically formed clays recorded the paleoclimate conditions of the deposit region. Palaeosols formed in a well-defined geological condition, especially, those which developed from magmatic materials, clay minerals, may have recoreded the paleo- climate changes. Since lacustrine or basin deposits have smaller source area comparative to marine sediments, clay minerals can be efficiently used to reconstruct the paleoclimate conditions of the region. The cv and tv structures of clay mineral crystals can be used to indicate their provenance, detrital or authigenical origin. In study of weathering modified laterite profile, clay mineralogical method has the advantage over other methods for intense chemical weathering, leaching, and migration. Clay mineral subspecies, transition phases, and authigenically formed clays during deposition are much more sensitive to climate changes, more attention should he paid to these clays in the future study. In addition, paleoclimate interpretation of stable isotope of authigenically formed clays could be a promising method in orogenic belts.