Establishing exploration vectors to infer the properties of ore-forming fluids, locate blind ore bodies with the aid of visible to near-infrared (VNIR) and short-wave infrared (SWIR) spectroscopy, and infer the chemistry of minerals, is a new research interest for economic geology. Common alterations and clay minerals, including sericite, chlorite, epidote, alunite, kaolinite, tourmaline, etc., are ideal objects for the study of exploration indicators due to their sensitivity to variations in the nature of hydrothermal fluid. The diagnostic spectral feature and chemistry vary spatially and systematically with physicochemical change. VNIR spectroscopy can characterize the REE-bearing clay minerals directly. Obtaining spectral or chemical parameters with the aid of VNIR-SWIR spectroscopy, electron probe micro-analyzer (EPMA) or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) can help to establish exploration vectors. This paper systematically summarizes recent advances in mineral exploration indicators (MEIs) of VNIR-SWIR spectroscopy and chemistry, and compares them in different regions or deposits. We found that some MEI spatial variation trends are random, even the same type of deposit can show an opposite trend. The controlling factors that limit the application of the established MEIs are vague. Conducting further research on petrology and mineralogy with the aids of observation under microscopy, X-ray diffraction (XRD), TESCAN Integrated Mineral Analyzer (TIMA), and EPMA are suggested to discover alteration mineral assemblage, alteration stages, and behaviors of “the pathfinder elements” related to mineralization. Based on the above research, the physicochemical properties of ore-forming fluids and their control over MEIs can be inferred. Refining the theoretical basis is critical to understanding and popularization of spectral and chemical MEIs.

Chromite is a strategic mineral resource for many countries, and chromite deposit occurrences are widespread in the ultramafic rocks of the Yarlung Zangbo ophiolite belt, particularly in the harzburgite unit of the mantle section. Conducting field surveys in complex and poorly accessible terrain is challenging, expensive, and time-consuming. Remote sensing is an advanced method of achieving modern geological work and is a powerful technical means of geological research and mineral exploration. In order to delineate outcrops of chromite-bearing mantle peridotite, the present research study integrates seven image-enhancement techniques, including optimal band combination, decorrelation stretching, band ratio, independent component analysis, principal component analysis, minimum noise fraction, and false color composite, for the interpretation of Landsat8 OLI and WorldView-2 satellite data. This integrated approach allows the effective discrimination of chromite-containing peridotite outcrops in the Luobusa area, Tibet. The interpretation results derived from these integrated image-processing techniques were systematically verified in the field and formed the basis of the feature selection process of different lithologies supported by the support vector machine algorithm. Furthermore, the distribution range of the ferric contamination anomaly is detected through the de-interference abnormal principal component thresholding technique, which shows a high spatial matching relationship with mantle peridotite. This is the first study to utilize Landsat8 OLI and WorldView-2 remote sensing satellite data to explore the largest chromite deposit in China, which enriches the research methods for the chromite deposits in the Luobusa area. Accordingly, the results of this investigation indicate that the integration of information extracted from image-processing algorithms using remote sensing data could be a broadly applicable tool for prospecting chromite ore deposits associated with ophiolitic complexes in mountainous and inaccessible regions such as Tibet’s ophiolitic zones.

A combination of microstructural, fluid inclusion, and in situ sulfur isotopic analyses of pyrite, along with major and trace element studies of the mineralization-hosting sandstone, reveals the complexity of its genesis from the Jurassic Toutunhe Formation in the Liuhuanggou sandstone-hosted uranium deposit, Southern Junggar Basin. Based on field geological investigations and the geochemical characteristics, it is concluded that the source of the ore-bearing sandstones originates from felsic igneous rocks in the Northern Tianshan and Central Tianshan regions. Through optical microscopy and scanning electron microscopy (SEM), three generations of pyrite were identified: framboidal pyrite, concentric overgrown pyrite, and sub-idiomorphic to idiomorphic cement pyrite. The sulfur isotopes of the pyrite were analyzed using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The results indicate that each type of pyrite has distinct sulfur isotope compositions (the framboidal pyrite: −16.85‰ to +2.16‰, the concentric overgrown pyrite: −7.86‰ to +10.32‰, the sub-idiomorphic to idiomorphic cement pyrite: +9.16‰ to +16.77‰). The framboidal pyrite and the sub-idiomorphic to idiomorphic cement pyrite were formed through bacterial sulfate reduction (BSR), while the concentric overgrown pyrite was formed through thermochemical sulfate reduction (TSR) triggered by the upward migration of hydrocarbons. The discovery of hydrocarbon inclusions provides evidence for the involvement of deep-seated reducing fluids in uranium mineralization. Uranium mineralization occurred in two distinct stages: (1) The early stage involved the interaction of uranium-bearing fluids with reductants in the mineralization-hosting strata under the influence of groundwater dynamics, leading to initial uranium enrichment. (2) The later stage involved the upward migration of deep-seated hydrocarbons along faults, which enhanced the reducing capacity of the sandstone and resulted in further uranium enrichment and mineralization.