浅谈重矿物在表层沉积物物源和沉积环境分析中的应用

Application of Heavy Minerals in Analysis of Source and Sedimentary Environment of Surface Sediment

重矿物分析法是分析沉积物物源,反演沉积环境的有效方法。尽管重矿物在沉积物中的含量不高,但由于部分重矿物耐腐蚀和稳定性强的特点,重矿物能够较好地保存源区信息。目前,主要通过重矿物的组成和分布特征以及地球化学特征分析物源和沉积环境。利用重矿物的矿物特征评价主要包括重矿物的含量变化,物理特征,重矿物特征指数(ATi、GZi、RZi,ZTR、MZi、Cti),UM/SM(不稳定矿物与稳定矿物组合的比值)以及Q聚分析法等多个指标和方法。重矿物的地球化学方法主要通过分析部分重矿物如辉石、普通角闪石、石榴子石等化学成分的差异判别源区。还可以通过测试错石、独居杠等矿物的同位素年龄,与周围岩石的同位素年龄对比得出源区信息。然而,不同的分析方法受风化、搬运、沉积等因素影响,有其白身的局限性,因此要综合多种分析方法,才能更准确地分析沉积物的物源区以及沉积环境。

Heavy mineral analysis is an effective way to determine the source of sediment and invert the depositional environment.Due to the strong corrosion resistance and stability,it can preserve the information of the mother rock well.The mineral characteristics and geochemical characteristics of heavy minerals are commonly used to study source information and sedimentary environment.The mineral characterization of heavy minerals mainly includes the content characteristics and physical characteristics.The content changes,the mineral characteristics index(ATi GZi RZi ZTR MZi Cti),UM/SM(the ratio of unstable heavy minerals combinations to heavy stable mineral combinations)and Q-cluster analysis are common used.These indications and methods are based on heavy mineral contents.Geochemical methods of heavy minerals mainly study the different compositions of some heavy minerals such as pyroxene,homblende and garnet to identify the source area.It also can obtain the isotopic age of some heavy minerals such as zircon and monazite.And the source information is obtained by comparing the heavy mineral isotopic age and isotopic age of surrounding rocks.However,different analytical methods are influenced by weathering,transport,sedimentation and more.It is necessary to synthesize a variety of analytical methods to analyze the source area and sedimentary environment of sediments.