石英ESR法在黄河现代沉积物物源示踪研究中的可行性分析

Feasibility analysis of quartz Electron Spin Resonance method in tracing provenance of modern sediments in the Yellow River

石英ESR信号示踪法作为一种新的物源示踪方法,已经被较好地应用于东亚地质历史时期风尘堆积物和现代沙尘沉降物的物源示踪研究中。首先简要回顾了石英ESR信号示踪法的研究现状,进一步基于石英ESR信号示踪法的母岩年代和结晶度原理,探讨该方法对黄河沉积物物源示踪的可行性及应用前景。

Background,aim,and scope As a new provenance tracing method,electron spin resonance (ESR) signal intensity and crystallinity index (CI) of quartz were widely used in tracing the material sources of marine dust,Asian dust and loess.Firstly,the present researches about the ESR provenance tracer were briefly reviewed.Based on this,we take the Yellow River Basin as the research area to analyze the feasibility of quartz ESR method to trace modern Yellow River sediments.Materials and methods As one of the most common and abundant minerals on the earth,the quartz has been selected to study material owing due to its stability in the process of weathering,denudation and sedimentation,which may preferably save the primitive character of the host rocks.ESR signal intensity of the ■centre (an indication of the age of the host rock) and CI (an index reflecting the formation condition of the mineral such as temperature and crystallization speed) of quartz have been tested for the provenance identification.Results Based on the application successes and feasibility analysis on provenance of the marine sediments,Asian dust and loess,the provenance tracing the Yellow River will be proposed by the method of the ESR and CI.Discussion If the method of ESR and CI could successful trace the identification of the Yellow River sediments,the following chief characters should be needed:(1) the stability of the chose object (keeping the primitive character in the process of the physical and chemical weathering);(2) identification of provenance tracer (having the obvious identification in rock age and formation condition);(3) the stability of provenance material (having the preferably supply relation between the provenance and deposition);(4) the accessibility of sediments (having the unanimous mixed sediments among the main steam and other branches).Conclusions Compared with the provenance tracer of eolian sediments,the provenance of the river sediments had more spatial cause and temporal variability.The paper discussed the feasibility of the method of ESR and CI in the sediments of the Yellow River,which perfectly accorded with the stability of the object,identification of signal intensity,stability of provenance material and accessibility of sediments.Therefore,the provenance tracer of ESR and CI of quartz was considered as a promising method to trace the Yellow River sediments.Recommendations and perspectives The quartz ESR method is feasible for the study of sediment tracing in the Yellow River,but the Yellow River has the characteristics of large basin,complex and diverse rocks,and the single tracing method is difficult to accurately identify the source area information of sediment,so this method still needs to be cautiously applied sediment tracing in the Yellow River.