Evolution of a karst polje influenced by glaciation: The Gomance piedmont polje (northern Dinaric Alps)

Abstract

Gomance is a piedmont karst polje in the northern Dinaric Alps presenting geomorphological and sedimentological evidence of past glaciation. During the Pleistocene the polje was situated at the edge of the Snežnik and Gorski Kotar ice fields from where two outlet glaciers reached Gomance. The morphogenesis of the polje was reconstructed by means of geomorphological mapping, sedimentological studies, and ground penetrating radar (GPR) measurements, supported by hand-drillings. With GPR an almost entirely buried moraine system was also imaged and mapped, crucial in reconstructing the polje history. The depression was karstified and well drained without any surface streams before the Last Glaciation. When the glacier front reached the depression, the entire floor became covered by glacial and outwash deposits.Surface runoff dominated over karst drainage in a large part of the polje, particularly where distal outwash deposits with low effective porosity functioned as an aquitard. These deposits diverted surface drainage toward the lowest edge of the polje, which functioned as a ponor front along the entire length. The outwash system of the Gomance polje was active during the Last Glaciation as suggested by radiocarbon-dated outwash deposits.

An overview of Alpine and Mediterranean palaeogeography, terrestrial ecosystems and climate history during MIS 3 with focus on the Middle to Upper Palaeolithic transition

“…The Balkan Peninsula was deeply studied in the last decay (see Hughes and Woodward, 2016 for a review). Therein, mountain glaciers developed in a karstic environment with specific characteristics (Adamson et al, 2014;Žebre and Stepišnik, 2015;Žebre et al, 2016). Most of the outwash system into the karstic network and the outwash fans were very confined and limited to the basins where glaciers flowed (Žebre et al, 2016, 2019).…”

Geomorphology of Blidinje, Dinaric Alps (Bosnia and Herzegovina)

“…This situation is particularly common for the mountains in southwestern Bosnia and Herzegovina, where non-carbonate rocks underlie carbonate massifs, forming fluvial relief with restricted space for the formation of a piedmont-type glacier. However, several past glaciated high plateaux in the Dinaric Alps are surrounded by karst poljes, containing some of the thickest and best-preserved glacigenic deposits in the Mediterranean (Adamson et al, 2014;Žebre et al, 2016). An example of well-preserved outwash and till deposits is Orjen Mountain in Montenegro (Adamson et al, 2014;Hughes, 2010).…”

“…Cvijić, 1899;Grund, 1902;Milojević, 1935;Žebre & Stepišnik, 2015b), as well as other elevated sections of the Dinaric Mountains in Albania (Milivojević, Menković, & Ćalić, 2008), Montenegro (Hughes, Woodward, van Calsteren, & Thomas, 2011;Žebre & Stepišnik, 2014), Croatia (Marjanac & Marjanac, 2004) and Slovenia (Žebre & Stepišnik, 2015a;Žebre, Stepišnik, Colucci, Forte, & Monegato, 2016). They not only hosted cirque and valley glaciers, but also large ice caps, which were some of the largest in the Mediterranean owing to a sustained moisture supply during cold stages (Adamson, Woodward, & Hughes, 2014).…”

Glaciokarst landforms in the Siera de los Grajos, Babia and Luna natural park (Cantabrian Mountains, NW Spain)

“…The infiltration of the subglacial water into the karst network reduces overland flow, which modifies the discharges of the pro-glacial streams and the sediments they carry. Therefore, when glacier dynamics converge with a subglacial karst (Žebre & Stepišnik 2015), a type of landscape that combines the reliefs derived from both processes, named glaciokarst, is generated (Ford 1979;Smart 2004;Žebre & Stepišnik 2015).During cold stages of the Pleistocene, these dynamics has been common in the calcareous mountains at middle latitudes (Johnson & Stieglizt 1990;Bodgdan & Leszek 1999;Goldie 2006;Lepirica 2008;Hughes et al 2010;Telbisz et al 2011;Adamson et al 2014;Stepišnik 2014;Žebre & Stepišnik 2015;Žebre et al 2016), and also in limestone outcrops of the Cantabrian Mountains were the glacial processes were intense (Jalut et al 2010;Serrano et al 2012Serrano et al , 2013Frochoso et al 2013;Jiménez-Sánchez et al 2013;Santos-González et al 2013a;Gómez-Villar et al 2015;Rodríguez-Rodríguez et al 2016;Ruiz-Fernández et al 2016). However, in lower zones where this association does not occur, karst processes are dominant.…”