Quantitative paleotemperature reconstruction from Cueva Victoria speleothems using nucleation-assisted fluid inclusion microthermometry

Cueva Victoria is located in the semi-arid region of south-eastern Spain, one of the driest regions in Europe with mean annual precipitation of 200–300 mm and pronounced seasonality. The cave is hosted in Triassic dolomites and limestones of the Alpujarride Complex, part of the Inner Betic Cordillera, where karstification has enabled the development of extensive cave systems and flowstone formation. These flowstone deposits provide a sensitive archive of past climate variability.

Previous studies established robust ²³⁰Th/U chronologies spanning the last ~450 ka, demonstrating that speleothem growth occurred during both interglacial and warmer glacial periods, such as Marine Isotope Stage (MIS) 3, reflecting phases of enhanced regional moisture availability.

Here, we investigate flowstone samples VIC-III-4 and VIC-III-5, covering MIS 11c to MIS 7a (~430–190 ka), to evaluate their potential as quantitative paleotemperature archives. Preliminary nucleation-assisted (NA) fluid inclusion microthermometry measurements of a few flowstone samples yielded cave temperature estimates in agreement with the range of independently derived TEX₈₆-based temperature reconstructions from the same samples.

Detailed petrographic thin section analysis of the two flowstones indicates the presence of several fluid-inclusion-bearing growth layers that appear promising for NA fluid inclusion microthermometry. This provides the basis for targeted selection of additional microthermometry measurements and a more detailed analysis of the two flowstones. Although assisted (NA) fluid inclusion microthermometry has successfully been applied to speleothems from other regions, this study represents the first application to the Cueva Victoria flowstones and one of the first applications to a semi-arid cave system.

The combination of precisely dated high-resolution speleothem proxy records (stable isotopes, trace elements) with direct temperature reconstructions significantly enhances the potential of the Cueva Victoria flowstones for palaeoclimate reconstruction and will contribute to improving terrestrial paleoclimate reconstructions for the western Mediterranean region, an area highly sensitive to future hydroclimate change.