Provenance and paleoenvironmental dynamics of the Cheruvathur Formation in Northern Kerala, India: geological and geochemical perspectives

Abstract

The Neogene sedimentary successions in peninsular India remain poorly understood due to limited surface exposures. Recent infrastructural developments in northern Kerala, especially around Kasargod, have enabled detailed investigations of the Cheruvathur Formation, a stratigraphic equivalent of the Neogene Warkalli Formation. Multiple sedimentary sections were studied using granulometry, SEM, XRD, XRF, and ICP-MS techniques. The sediments are predominantly silty, with lesser amounts of gravel, sand, and clay, and show poor to moderate sorting with near-symmetrical grain distributions. Mineralogical data highlight kaolinite dominance, alongside quartz and goethite, reflecting intense chemical weathering in a warm, humid paleoclimate. Geochemical trends indicate that sediments are derived from intermediate to felsic source rocks, as supported by REE patterns. The sediments exhibit passive continental margin affinities, with high chemical maturity due to prolonged weathering. Grain size distributions and elemental ratios (Sr/Ba < 1; variable V/(V + Ni)) suggest deposition in a fluvial to shallow marine environment, with fluctuating freshwater-brackish conditions and redox alternations. This study establishes the Cheruvathur Formation as a product of intense tropical weathering, mixed-energy depositional systems, and a tectonically stable margin, providing critical insights into the paleoenvironmental and stratigraphic evolution of northern Kerala.