湖泊沉积物的矿物组成、成因、环境指示及研究进展

湖泊沉积物是不同地质、气候、水文条件下各类碎屑、黏土、自生/生物成因矿物以及有机物质等的综合体。沉积矿物蕴含着丰富区域和全球环境演变信息,如湖水的化学组成、流域构造、气候、水文以及人类活动的相互作用等。相关信息可以赋存在矿物外部微形貌、内部微结构、化学组成、物理和化学性质、同位素组成、谱学特征、成因以及共生组合等方面。因此,湖泊科学的许多关键课题都离不开矿物学,特别是在利用湖泊沉积物进行区域及过去全球变化研究中,深入的机理研究归根到底都要涉及矿物学,如流域化学风化作用、粒度组成、生物壳体化学组成、测年材料的选择等。然而,由于湖泊沉积物中矿物的多源性、复杂性,如何有效提取和解译其中的环境信息,是一项长期困扰研究者的课题,湖泊沉积矿物学的研究往往被许多研究者所忽视,中国的相关研究也较为薄弱。笔者综述了湖泊沉积物中碎屑、黏土、自生/生物矿物的矿物组合、特征、成因在(古)环境反演中的作用及最新研究进展,提出除了继续加强对湖泊沉积物中矿物来源、成因和古环境示踪的深入研究以外,矿物相间的转变及其对湖水和孔隙水组成的响应、一些非晶质或隐晶质及低丰度矿物相在湖泊化学和动力学中的作用也是很有潜力的研究领域,最后提出了研究中存在的一些问题、面对的挑战以及对研究前景的展望。

Composition,Origin and Environmental Interpretation of Minerals in Lake Sediments and Recent Progress

Lake sediment is an integrated content of detrital, clay, authigenic/biogenic minerals and organic matter under various geologic, climatic and hydrologic conditions. The minerals bear abundant information on regional and global environmental changes, such as lake water chemistry, basin tectonics, climate, hydrology, and human activity interaction, etc. The information hosts in external appearance, internal microstructures, chemical compositions, physical and chemical properties, isotopic compositions, spectroscopy, origin, and assemblage of minerals, etc. Therefore, many key topics of lake sciences are depended upon mineralogy, in particular during the reconstruction of past regional/global changes using lake sediments. The understanding on mechanism should involve in mineralogy, including catchment weathering processes, grain size variation, shell chemistry, and dating material. However, owing to various sources and complexity of minerals in lake sediments, how to withdraw and interpret mineral-bearing environmental information is a longstanding troubling, resulting in that mineralogy of lake sediments is overlooked often by some researchers, also in China. In this paper, the assemblage, characters and origins of detrital, clay, authigenic/biogenic minerals in lake sediments and their role in paleoenvironmental reconstruction were reviewed, then some potential research topics were suggested, such as the transformation among minerals and its response to chemistry of lake and pore waters, the roles in lake chemistry and dynamics of some amorphous, cryptocrystalline and low abundance minerals in lake sediments, in addition to the continued researches on lake mineral source, origin and paleoenvironmental tracing, and finally some problems and challenges were put further forward to.