Core Imaging Spectroscopy And Three-dimensional Alteration Modeling For Uranium Deposit In Xiangshan,Jiangxi

Alteration is an important prospecting element for hydrothermal deposits.For a long time,there has been a lack of effective technology support for fine detection and inversion of deep alteration information.Imaging spectroscopy is a frontier in earth observation,and has unique advantages in altered mineral mapping.In this study,taking the Heyuanbei and the Zoujiashan deposits as the research object,located in the western of Xiangshan uranium orefield,Jiangxi,the largest volcanic hydrothermal uranium orefield in China,imaging spectroscopy was introduced into the drill core alteration information identification and detection.Based on imaging hyperspectral scanning of drill cores,data processing and analysis,a set of technical methods were established including core alteration information extraction,logging and three-dimensional modeling,and realized semi-quantitative two-dimensional and three-dimensional visualization of deep hyperspectral alteration information.Combining with metallogenic dynamics,genetic mineralogy and XRD,the deep hydrothermal alteration process of Xiangshan and its association with uranium mineralization were discussed,which provided a new application demonstration for fine detection of deep alteration information and a reference for uranium exploration.The main achievements and understanding of this study are as follows:(1)Based on the processing of HySpex imaging spectrometer data,spectral similarity matching method,and relative content statistical method of core alteration information,an alteration information semi-quantitative logging technology using high-resolution core imaging spectrometer data was established,which can compensate the deficiencies of traditional geological logging in the degree of refinement and quantification.This technology have improved the objectivity and reliability of deep alteration information zoning,and provided a new idea and method for drill core logging in geology and mineral resources assessment.(2)Combined with geological statistics theory,continuous random variables were used to describe the development of deep alteration.A three-dimensional modeling technology for deep alteration information based on core imaging spectroscopy was established by means of the sequential Gaussian stochastic simulation.Five types of three-dimensional hyperspectral alteration models were constructed in the Heyuanbei deposit and the Zoujiashan deposit,which realized the three-dimensional fine inversion and visualization of deep alteration information.This technology provided a new support for the comprehensive study of the spatial characteristics of deep alteration and the metallogenic environment.(3)The results of three-dimensional alteration information modeling based on core imaging spectroscopy reflect that the Heyuanbei deposit and the Zoujiashan deposit have different alteration scales and types,and the Heyuanbei deposit may be located near another volcanic channel in the western of Xiangshan.Illitization,which is closely related to uranium mineralization,has two subtypes of short-wavelength and long-wavelength with Al-OH absorption peak.The short-wavelength illite is spatially related to kaolinite-dickite,and illitization has the spatial zoning characteristics of upper short-wavelength and lower long-wavelength illite.The illite associated with fluorite-hydromuscovite type uranium mineralization is mainly short-wavelength illite.(4)Combined with the late Mesozoic metallogenic geodynamic settings of Xiangshan volcanic basin,genetic mineralogy theory,XRD and alkali metasomatism mechanism,the formation and evolution process of a series of altered minerals in the deep part of Xiangshan after the formation of the volcanic basin were analyzed and predicted.A three-stage uranium metallogenic alteration evolution model was established,starting from sodium metasomatism to potassium metasomatism,followed by acid metasomatism from the view of time.Alkali metasomatism in the deep of Xiangshan is characterized by early sodium metasomatism late potassium metasomatism,early alkali metasomatism late acid metasomatism,and acidic minerals present in the upper part,and alkaline minerals present in the lower part.