Applications Of Hyperspectral Mineral Mapping In Mineral And Petroleum Exploration

Work reported in this thesis were focused on applications in mineral and petroleum explorations in order to demonstrate the efficiency and the value of hyperspectral technologies.In terms of the mode of data acquisition,both remote and proximal sensing were involved.In the Meiling-Hongshi-Honghai mining field of the Eastern Tianshan Mountains,the VMS style of poly-metallic mineralization is the most important target for exploration.In this mining field,airborne hyperspectral data were used to map the district-scale alteration,with emphasis on sericite,chlorite,pyrophyllite and Fe3+ oxides,each of which bears implications for a specific aspect of the hydrothermal processes involved.In the broad district scale,as revealed by hyperspectral data,massive sulfide mineralization tends to be formed near the boundary between strong phyllic and propyllitic alterations,whereas in a finer scale ore bodies are located where strong phyllic alteration zones and elevated abundance of Fe3+ oxides coexist.It is demonstrated that with the use of quantitative spectral parameters as proxies for alteration intensity,sutble trends in hydrothermal alteration and mineralization can be extracted from airborne hyperspectral data to better understand mineralization and guid exploration.In the thesis work,one case study of proximal sensing is on hyperspectral logging of drill core from the Dongji gold-silver deposit.For the time revealed,phyllic alteration in the deposit is characterized by sericite of shorter Al-OH band wavelengths,indicating more Al-rich sericite in or proximal to Au-Ag mineralization than that outside or distal to mineralization.The spectrally interpreted mineralogical data for the alteration assemblages at the current mining level suggest that underground mining has reached nearly the upper limit of temperature range favourable for low-sulfidation epithermal mineralization,and this therefore implies further exploration toward deeper parts may not be worthwhile.Efforts,instead,should be made on looking for geochemical anomalies with a lower temperature than the current mine as indicated by hydrothermal alteration interpretable from hyperspectral data.In the other proximal sensing case,hyperspectral data were used to extract information on petroluem and clay mineralogy in drill cuttings from the Erdos Basin.The results show that petroleum,even in minor to trace amounts,in sedimentary rocks can be quantified with spectral parameters.of clay minerals,illite-smectite mixed layers were found from the hyperspectral data to contain a significant amount of illite,implying a relatively high degree of thermal maturity.This then suggests that there may have been oil migration from the host sequence at the level of drill cuttings,which is also implied by spectrally indicated high content of NH4 in illite.The work therefore has confirmed that the hyperspectral technology can be applied in petroleum exploration as a field reconnaissance tool.Work in this thesis has demonstrated the value of hyperspectral technologies as tools for mineral and energy resource exploration,especially in terms of providing delicate and subtle mineralogical information on mineralization that can not be easily derived from other conventional analytical tools.Simple,rapid and effective data processing methods,based on existing ones with modifications to meet the particular geological and mineralization settings of the areas of study,were designed and tested and satisfactory results were derived.This prectice demonstrated the effectiveness and the cost-saving benefits of hyperspectral data processing with focus on a limited number of locally significant alteration minerals for application purposes.The work in this thesis also indicates that an application-oriented approach is the only way leading to successful commmercialisation of the hyperspectral technology.