LGM glaciation in the northern Dinaric Mountains, Slovenia: new insights from terrestrial cosmogenic nuclide dating and Parallel Ice Sheet Model simulation

The Dinaric Mountains are a mountain range stretching NW–SE from the Alps to the Albanides–Hellenides in central Europe. The highest parts were occupied by small ice fields and/or valley glaciers during the Quaternary cold periods, while even today some small glaciers still exist in topoclimatically favourable areas. The northernmost part of the Dinaric Mountains is called Trnovski Gozd (1495 m a.s.l.). It is a high karst plateau characterized by conical hills, uvalas, solution dolines, and numerous speleological features. In addition to the karst, Trnovski Gozd also has a palaeoglacial landscape above 1100 m a.s.l. Here, we present the glacial history of Trnovski Gozd, which was studied using geomorphological mapping, terrestrial cosmogenic nuclide (TCN, ³⁶ Cl) dating, and the Parallel Ice Sheet Modelling (PISM). The glacial evidence on the Trnovski Gozd is very scattered and sparse. Geomorphological mapping suggests a glaciated area of ~6 km ² . Five samples from boulders located on the crest of the largest moraine in the area were dated. The results yield a median age of 19.5±2.1 ka (corrected for a denudation rate of 20 mm ka ⁻¹ ) and are consistent with ages of the global Last Glacial Maximum (LGM). None of the Parallel Ice Sheet Model (PISM) simulations fully reproduce the geomorphologically reconstructed glacier extent. However, a scenario employing a temperature offset of −7.0 °C and a precipitation scaling factor of 0.95 relative to modern values provide the best fit, yielding a glaciated area of 27.4 km ² while successfully reproducing the position of the dated moraine. The Equilibrium Line Altitude (ELA) derived from the simulation results equals 1246 m a.s.l. and is similar to the LGM ELAs of some nearby isolated alpine glaciers. The temperature and precipitation offsets are also consistent with those observed across the Alps during the LGM. Reconstructions of isolated glaciers near the Alpine ice stream network provide valuable benchmarks for evaluating and refining palaeoclimate models.