Abstract

Terrestrial carbonates provide important archives for reconstructing paleoenvironmental, paleoclimatic and hydrogeological conditions in semi-arid to arid continental basins. This study investigates the origin, mineralogical characteristics and geochemical properties of calcrete and dolocrete occurrences developed along the Konya Fault Zone within the Konya Closed Basin (Central Türkiye). Field observations, petrography, XRD, SEM–EDS, major and trace element geochemistry, REE analyses, stable isotopes (δ13C–δ18O), geostatistical methods and ESR dating were employed. The results reveal two distinct terrestrial carbonate systems. Dolocretes occur within Quaternary alluvial fan deposits developed on ultramafic–ophiolitic rocks, whereas calcretes developed pedogenically within Quaternary alluvial fan deposits overlying carbonate bedrock. Calcite, dolomite, quartz, palygorskite and smectitic clay minerals constitute the principal mineral phases. Rhizoliths, tubular structures, nodules, microbial filaments and laminated carbonate horizons indicate pedogenic carbonate accumulation. The association of palygorskite with dolomite and smectitic clay minerals suggests alkaline, Mg-rich pore waters under semi-arid conditions. Elevated Sr concentrations indicate prolonged groundwater–carbonate interaction, whereas high Ni and Co contents in the dolocretes reflect the influence of ultramafic source rocks. REE distributions are characterized by LREE enrichment, weak Eu anomalies and locally developed negative Ce anomalies, indicating pedogenic fractionation under oxidizing meteoric conditions. Stable isotope data indicate precipitation from meteoric waters influenced by soil-derived CO2 under semi-arid climatic conditions dominated by C3 vegetation. ESR ages ranging from approximately 390–217 ka indicate carbonate formation during the Middle Pleistocene (MIS 11–MIS 7). Integrated mineralogical, geochemical, isotopic and chronological evidence indicates that the Konya terrestrial carbonates formed predominantly through pedogenic processes within meteoric vadose-zone conditions controlled by bedrock lithology (carbonate and ultramafic rocks), groundwater circulation and Quaternary climatic variability. These deposits represent important archives of Middle Pleistocene paleoenvironmental and paleohydrological evolution in Central Anatolia.

IPC Classification

Keywords