LAUSR

This study performed a stable isotope and redox-sensitive trace-element investigation on the Gotan Limestone and Pondlo Dolomite of the Bilara Group, Marwar Supergroup to decipher the palaeodepositional redox condition. A multivariate-statistical analysis of geochemical data set (δ 13 C-carb, δ 18 O-carb, δ 13 C-org, TOC, V, Ni, Cu, Zn, Mo, Pb, and U) reveals that limestone and dolomite units of the Bilara Group were deposited under two different redox regimes. Dolomite has an average δ 13 C-org values ~ − 30.0 ‰ and shows a statistically significant negative correlation with δ 13 C-carb which indicates an oxygen-depleted closed palaeodepositional environment. Dolomite δ 13 C-carb also shows a statistically significant negative correlation with redox-sensitive trace elements V, Ce, Pb, and U which infer higher secondary productivity during the dolomite deposition. The limestone has an average δ 13 C-org values ~ − 28.9 ‰ and δ 13 C-carb shows a significant positive correlation with δ 18 O-carb and Sr, whereas δ 13 C-carb shows a significant negative correlation with V and U. These statistical relationships among the geochemical parameter are indicative of suboxic-to-oxic water column with a relatively higher depth that received a significant input of water discharge from the terrestrial region. This discharge may have brought nutrients and other weathering-derived ions into the basin.