Characterizing the genesis of terrestrial carbonates is fundamental for deciphering their role as archives of tectonic, climatic, and hydrochemical processes. However, differentiating between cold/warm, hypogene/epigean, and biotic/abiotic processes is not straightforward. Here, we study ~30 m thick carbonate deposits in Vedi Valley, the Ararat Basin, Armenia, formed in a tectonically active fault-controlled spring system. The study investigates their genesis and environmental context by applying geological mapping, petrographic, isotopic, geochemical, and U-series dating methods to unravel the depositional and diagenetic history of these deposits.
Two distinct facies are identified: (1) microbial carbonate facies associated with low-temperature palustrine settings, characterized by micritic and peloidal biotic textures, and (2) sparitic calcite facies linked to CO₂ degassing from saturated hypogene solutions, filling fractures. δ¹³CVPDB values range from +7.5‰ to +10‰ and δ¹⁸OVPDB values range between -9.6‰ and -11.6‰, indicating deeply sourced fluids. Sr and Ba concentrations suggest the interaction with buried marine carbonates, most likely those comprising the Erakh Anticline.
Co-variations in the isotopic ratios alongside Mg, Ca, and Sr concentrations point to a pristine closed degassing system at earlier stages and the incorporation of meteoric influx above 19 m depth. This upper part also shows three phases of enhanced detrital accumulation during increased runoff, possibly related to interglacials. The established chronological framework through U-Th constrains the deposition to between 319 ± 84 ka and 198 ± 14 ka, corresponding to MIS 9–7. This period coincided with profound global and regional environmental shifts triggered by changes in climate and tectonic activity. This chronostratigraphy highlights the potential of fault-controlled spring deposits, such as those in Vedi, as regional paleoenvironmental archive.