Application of geochemical anomaly identification methods in mapping of intermediate and felsic igneous rocks in eastern Tianshan, China

摘要

Marine volcanic-sedimentary Fe deposit is an important type of mineral deposit in eastern Tianshan mineralization district, China. In this paper, igneous rocks associated with Fe mineralization are characterized by GIS-based methods of spatial analysis to support future mineral exploration. Some potentially mineralized areas are masked by overburden materials in the Gobi desert region. Stream sediment geochemical data of SiO2, Al2O3, K2O, Na2O; CaO, MgO, Fe2O3, Ba, Be and Li are integrated using principal component analysis to map igneous rocks. In order to reduce the influence of covers on geochemical signal, the singularity index developed in the context of multifractals was applied to analyze stream sediment geochemical data to identify weak geochemical anomalies. Potential areas in the integration results of principal component analysis are constrained by confining influences of overburden on elemental migration in stream sediments. The integration of various geochemical anomalies indicates well the spatial distribution of either outcropping or concealed igneous rocks. Based on characteristics of the eastern Tianshan district, the current study demonstrates the usefulness of the methods described for recognition of possible concealed igneous rocks in a desert covered area.