CHEMOSTRATIGRAPHY OF KARST ICE, PARADANA CAVE, SLOVENIA

Velika Ledena Jama v Paradani or Paradana Cave, is the best-known ice cave in Slovenia. Its entrance sits at 1135 m.a.s.l. in the High Dinaric Karst Plateau, Trnovski gozd, in Western Slovenia. The cave is 7311 m long and 858 m deep. The entrance to the cave is a funnel-like depression formed by collapse. Ice occurs in the entrance to the cave and down to depths of approximately 100 m below the entrance. Based on measurements of air movements and temperatures, ice formation has been attributed exclusively to air circulation. During the middle to late 19^th century, ice was extracted from the cave as an economic product. It has been reported that just in a single year, in 1867, 800 m³ of ice had been extracted and sold to the coastal city of Trieste. Since at least the 1950s the amount of ice in the entrance area has been observed to wax and wane. In the mid-20^th century the amount of ice was estimated to be ~4000 m³ and in the beginning of the 21^st century at ~2000 m³. In July 2017, we sampled a 230 cm vertical profile of ice in the north-west section of the Entrance Chamber. The ice samples were thawed and one aliquot was taken for δ¹⁸O and δD analyses. Other aliquots were filtered and analyzed for major cations and anions, H₄SiO₄, nitrate and soluble reactive phosphate. In addition to the ice samples, two melt water pools sitting on ice within the cave were sampled for the same constituents as noted above. The motivation for this work is to (1) describe the biogeochemical character of the ice; (2) compare the ice chemical characteristics to the regional groundwater and spring water; (3) attempt to discern the relative age and timing of ice accumulation in the cave; and (4) determine the significance of ice as a possible source of palaeoclimatic information. Because this ice cave is considered a form of permafrost, we seek to document its future fate in a warming climate. The biogeochemical data will be presented and discussed within this climate framework.