The Jaban meta-conglomerate with wacke (JMW) of the Champaner Group represents a polymictic clastic unit important for understanding sediment provenance, basin evolution and post-depositional processes within Proterozoic supracrustal sequences. This study integrates field observations, petrography, bulk rock major and trace element geochemistry, and in situ mineral chemical analyses to constrain provenance characteristics, depositional conditions and post-depositional element redistribution within this unit. The heterogeneous clast assemblage, including quartzite, granite, calc-silicate and phyllite, indicates derivation from multiple felsic-dominated crustal sources, including older Champaner Group lithologies, pre-Champaner granitic gneiss and granitoid bodies of the Godhra region. Petrographic observations indicate a mineral assemblage dominated by quartz, feldspar and micas with accessory heavy minerals including zircon, monazite and hematite. Geochemical signatures, including mixed tectonic discrimination indicators, elevated Th/Sc and Zr/Sc ratios reflecting significant sediment recycling from felsic upper crustal sources, marked negative Eu anomalies, and depletion in Heavy Rare Earth Elements (HREEs), together with immature textures and poor preservation of primary sedimentary structures, suggest deposition within a tectonically influenced continental margin basin setting, followed by deformation, sediment reworking and tectono-magmatic overprinting. In-situ mineral oxide data confirms the presence of uranium and thorium within heavy minerals and selected silicate phases. X-ray elemental mapping reveals localised enrichment of U and Th, particularly along structurally controlled zones towards the northern part of the JMW belt. These results indicate post-depositional redistribution of radioactive elements associated with hydrothermal fluid–rock interaction, likely linked to prolonged granitoid magmatism. Overall, the JMW succession records sediment recycling, tectonic reworking and fluid-mediated geochemical modification, providing insight into crustal recycling processes within Proterozoic Champaner Basin.
Incised valley-fills are widely recognized as key stratigraphic and sedimentological archives, yet lacustrine examples remain comparatively understudied relative to their marine counterparts. This study investigates Late Miocene incised valleys of Lake Pannon and places them into a global context by comparing their morphology, fill characteristics, and controlling factors with both lacustrine and marine analogs. The Pannonian valleys are typically 15–20 m deep, a few hundred meters wide and filled predominantly with fluvial sediments. Their architecture is characterized by fining-upward successions with mud-clast conglomerate bottom units and cross-stratified sand bodies, capped by fine-grained, organic-rich deposits that record progressive shallowing and marsh development. Multiple mud-clast conglomerate horizons within the valley-fills reflect repeated cut and fill processes, indicating that infill of the valleys were compound with smaller-scale water-level fluctuations. The valleys most commonly cut into mud-prone delta slope deposits and are overlain by the subsequent delta slope succession.Global lacustrine case studies (e.g., Junggar Basin, Ordos Basin, Sichuan Basin, Knoll Basin, Caspian “Sea”) reveal average dimensions of ∼3 km in width and ∼28 m in depth, with both climatically and tectonically driven base-level changes recorded. Climate-driven glacio-eustatic fluctuations are pointed out dominantly as the cause of water-level change in lacustrine basins. Comparative analysis further shows that lacustrine valleys are narrower and shallower than marine examples, though both environments exhibit a positive width–depth relationship.Lacustrine, fluvially dominated, overfilled incised valleys present favorable storage potential for various fluids (subsurface water, hydrocarbons, CO2, H2, etc.) due to their well-confined sand bodies, sealed most commonly laterally and vertically by mudstone and siltstone units. This study provides a foundation for a database to be expanded in the future, which will contribute to improved recognition and understanding of lacustrine incised valley-fills and their reservoir potential.
The Khariar Alkaline Complex (KAC), emplaced within the Terrane Boundary Shear Zone (TBSZ) along the boundary between the Eastern Ghats Mobile Belt (EGMB) and the Bastar Craton, represents an important Mesoproterozoic alkaline magmatic centre developed during intracontinental extension along a long-lived craton–mobile belt interface. Nepheline syenite constitutes the dominant lithology and is composed of nepheline, K-feldspar (orthoclase–perthite), aegirine, amphibole, biotite, apatite, titanite, and opaque phases, with garnet-bearing variants containing calcic garnet enriched in andradite–grossular components. Field and petrographic evidence indicate two distinct emplacement phases: an early deformed and metamorphosed suite exhibiting syn-tectonic fabrics, and a younger, massive, undeformed suite indicative of post-tectonic intrusion. Geochemically, the nepheline syenites are silica-undersaturated, miaskitic foid syenites with high-K alkaline affinity. They are characterized by low concentrations of compatible elements (Ni, Cr and Co), enrichment in large-ion lithophile elements (Sr, Ba and Rb) and high-field-strength elements (particularly Zr and Nb), and strongly fractionated chondrite-normalized REE patterns marked by elevated (La/Yb)ₙ ratios and comparatively flat HREE segments. The absence of systematic Nb–Ta depletion, together with low Th/Ce ratios (0.03–0.1), suggests limited crustal contamination and argues against a typical subduction-related affinity. Variable Eu anomalies are interpreted to reflect feldspar-controlled fractionation and crystal accumulation during magma evolution. Trace-element systematics indicate derivation from an enriched, metasomatized mantle source, predominantly within the spinel lherzolite stability field, possibly close to the garnet–spinel transition zone, and generated through low to moderate degrees of partial melting. The geochemical characteristics further indicate melting of a phlogopite ± amphibole-bearing metasomatized subcontinental lithospheric mantle, with probable interaction between enriched lithospheric mantle and asthenospheric melts during intracontinental extension. The nepheline syenites are interpreted to have formed in an intraplate extensional setting along the Bastar Craton–Eastern Ghats Mobile Belt margin and were subsequently affected by deformation and metamorphic reworking during Pan-African tectonism associated with reactivation of the terrane boundary zone. The younger intrusive phase records continued alkaline magmatism during prolonged tectonic reactivation of the TBSZ. Collectively, the Khariar Alkaline Complex forms part of a regionally developed Mesoproterozoic alkaline magmatic province along the EGMB–Bastar Craton margin and provides important insights into lithosphere–mantle interaction, mantle metasomatism, continental rifting, and subsequent Pan-African tectono-metamorphic reworking during the Proterozoic evolution of the Eastern Indian Shield.
