The study of fluid inclusions is important for understanding various geologic processes involving geofluids. However, there are a number of problems that are frequently encountered in the study of fluid inclusions, especially by beginners, and many of these problems are critical for the validity of the fluid inclusion data and their interpretations. This paper discusses some of the most common problems and/or pitfalls, including those related to fluid inclusion petrography, metastability, fluid phase relationships, fluid temperature and pressure calculation and interpretation, bulk fluid inclusion analysis, and data presentation. A total of 16 problems, many of which have been discussed in the literature, are described and analyzed systematically. The causes of the problems, their potential impact on data quality and interpretation, as well as possible remediation or alleviation, are discussed.

The rising demand of strategic metals, especially lithium, necessitates discovery of new resources to meet the global supply chain. Recently, several pegmatite-hosted rare metal (Li-Rb-Be-Nb-Ta) deposits have been discovered in the Western Kunlun orogenic belt, making it a new world-class rare metal resource (estimated ~7 Mt Li₂O and 0.16 Mt BeO). Understanding the metallogenesis of this belt is critical to further evaluate the rare metal potential. In this study, columbite-tantalite (coltan) and monazite from rare metal pegmatites and zircon from potential parental granites were collected from five representative rare metal pegmatite deposits in the western, middle, and eastern parts of the Western Kunlun orogenic belt for U-Pb geochronology. The results indicate that despite the distances of the sampling localities in different parts of the Western Kunlun orogenic belt, the ages of pegmatite-hosted rare metal mineralization fall in a narrow range of ca. 208–204 Ma. These rare metal pegmatites are temporally and spatially related to adjacent postorogenic granites emplaced following the closure of the Paleo-Tethys Ocean. The compositional characteristics of K-feldspar, biotite, and muscovite of the granites and pegmatites, along with regional mineralogical and textural zonation of the pegmatites, suggest that the rare metal pegmatites were derived from the volumetrically much more important, highly fractionated granitic intrusions. We propose that, in combination with the data from previous studies, the 218–204 Ma interval represents a newly recognized rare metal metallogenic period linked with granitic intrusions in the Western Kunlun orogenic belt, revealing a 600-km-long late Triassic rare metal pegmatite belt composed of multiple ore fields formed in a similar metallogenic setting. These results emphasize the importance of identifying fertile, Late Triassic to Early Jurassic granitic intrusions for rare metal pegmatite exploration. Furthermore, combined with recent studies on the Songpan-Ganzi rare metal pegmatite belt along the eastern segment of the Paleo-Tethys, this study further highlights the great potential of rare metal resources in this global tectonic zone.

The unconformity-related U deposits associated with the Proterozoic Athabasca Basin are among the largest and richest U deposits in the world. The conventional genetic model suggests that mineralization occurred under deep-burial (>5 km), diagenetic-hydrothermal conditions at normal geothermal gradients (~35°C/km). Based on regional geochronostratigraphic and ore geochronological data, it is inferred that, at the time of primary U mineralization (≥ ca. 1540 Ma), the burial depths of the unconformity surface were likely <~3 km. The elevated fluid pressures (up to 1,500 bars) used to support the deep-burial model were probably overestimated due to misinterpretation of accidentally entrapped halite crystals as daughter minerals in fluid inclusions. The elevated fluid temperatures (180°–250°C) estimated from fluid inclusion and clay mineral geothermometry from both mineralized and barren areas, which were interpreted to have resulted from deep burial at normal geothermal gradients at the time of mineralization, may be alternatively explained by local or basin-scale elevation of geothermal gradients at the time of mineralization, followed by continued burial and/or temporarily increased thermal gradients after mineralization. The shallow-burial mineralization model can better explain the geologic characteristics of the unconformity-related U deposits, including development of pervasive clay alteration halos, breccia zones, and dissolution vugs locally filled with drusy quartz, as well as evidence of fluid boiling recorded by fluid inclusions. The modified model emphasizes the importance of combined basinal (development of brines) and deep-seated geodynamic factors for large-scale U mineralization. Recognition of these factors is important for U exploration in the Athabasca Basin and similar basins elsewhere.