Quartz trace element geochemistry and internal morphology as proxies for provenance characterization: Results from the Marwar basin, NW India

Abstract

Quartz as one of the most stable minerals in sedimentary processes, is widely distributed in clastic sedimentary rocks, making it a potential provenance tracer in the source-to-sink system. In this study, internal morphology and trace element geochemistry of detrital quartz from the Marwar sandstones in NW India were utilized to decipher the source lithologies. Quartz from various source rocks displays distinctive trace element characteristics that correspond to specific cathodoluminescence properties. Phenocrystic quartz in hypabyssal and volcanic rocks is characterized by higher Li (>10 ppm), Al (>90 ppm), and Ti (>60 ppm) contents, medium to bright blue cathodoluminescences, and visible zoning. Quartz in plutonic rocks, especially diorite, contains a lower abundance of trace elements. It exhibits dark brownish red, violet to blue cathodoluminescence, and is marked by dark streaks, patches, and partial healing fractures. Pegmatitic quartz with the lowest Li (0.03 ppm) and the highest Ge (1.38 ppm) contents, displays brown to dark blue cathodoluminescences. Gneissic quartz with the highest Fe (3.98 ppm) and a moderate abundance of other trace elements, exhibits non-luminescence or dark brown to dark blue cathodoluminescence, occasional dark streaks, and healing fractures. Quartz in migmatites generally shows a lower trace elements abundance, non-luminescence, or dark brown to dark blue cathodoluminescence. A robust statistical correlation between the cathodoluminescence properties and trace element characteristics is discernible in the detrital quartz grains through the entire stratigraphy of the Marwar Supergroup, shedding light on the lithological and compositional make-up of the provenances. This study identifies that the early sedimentation in the Marwar basin was predominantly fed by detritus from the Neoproterozoic Malani Igneous Suite and Paleoproterozoic granitoids, whereas the younger strata document a marked increase in contributions from the older Aravalli Craton basement. Our findings demonstrate the utility of quartz trace element geochemistry and internal morphology as effective tools for provenance analysis in source-to-sink systems. Moreover, detrital quartz and zircon in combination can be effectively used in tracing the specific source and quantifying relative contributions from different source rocks that could be applied to provenance studies elsewhere.