Geochemical Investigation of Paleoproterozoic Siliclastic Rocks: Implications for Evolution of North Indian Craton.

Geochemical Investigation of Paleoproterozoic Siliclastic Rocks: Implications for Evolution of North Indian Craton.

Sadia Khanam¹, Nurul Absar², Mohammad Adnan Quasim¹

• 1-  Aligarh Muslim University
• 2- Pondicherry University

The Paleoproterozoic was the most significant era in geological history, during which crustal stabilization occurred, and Earth began to develop an atmosphere habitable to life after the Great Oxygenation Event. Paleoproterozoic cratonic rocks preserve chemical signatures that provide insight into the onset of plate tectonics, supercontinent assembly, and the Great Oxidation Event, offering a unique archive for reconstructing Earth’s first billion years and guiding mineral resource exploration. The Indian subcontinent has a unique cratonic nucleus comprised of rocks of   the Paleoproterozoic, that is, the Aravalli craton. However, few studies have been conducted on the complete evolution of the Aravalli Craton. To this end, we investigated the Paleoproterozoic Rajgarh Formation of the Alwar sub-basin, North Delhi Fold Belt. This study provides critical insights into the provenance, depositional environment, and tectonic setting of the North Indian Craton (NIC) through petrographic, mineralogical, and geochemical analyses. The sandstones are quartzarenite to arkosic in nature and composed of monocrystalline quartz with undulose extinction, feldspars, micas, cordierite, and heavy minerals, including zircon, garnet, and tourmaline. Modal analysis and Qt–F–RF ternary plots indicate cratonic interior provenance. Chondrite-normalized REE patterns display fractionated LREE, flat HREE, and negative Eu anomalies (average Eu/Eu* = 0.76), consistent with felsic to intermediate sources such as granitoids, TTG gneisses, and granulites of the Banded Gneissic Complex and the Sandmata Complex. Trace element ratios (Th/Sc, La/Sc, La/Yb, and Cr/V) and discrimination diagrams (La–Th–Sc, Th–Sc–Zr/10, Ga with V and Sn) also suggest derivation from felsic crust in active to passive margin settings. Redox-sensitive proxies (U, V, Mo, Cd and EF of RSTE) and pyrite occurrence indicate deposition in oxic to sub-oxic shallow-marine environments with intermittent dysoxic phases. Collectively, the Rajgarh Formation of Alwar sub-basin records a complete tectonic cycle: intracratonic rifting and basin initiation, felsic-dominated sediment supply, shallow-marine rift deposition, and basin stabilization during the Mesoproterozoic Delhi Orogeny. Comparisons with other Purana basins (Vindhyan, Cuddapah, and Bayana) demonstrate that the NIC experienced widespread intracratonic extension during the Columbia supercontinent cycle, followed by stabilization during Rodinia accretion.