Origin and Evolution of Basins in the Eastern Part of Jasło-Sanok Depression (Polish Carpathians) in the Late Vistulian and Holocene
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Studia Quaternaria, vol. 36, no. 2 (2019): 171–194 DOI: 10.24425/sq.2019.126388 ORIGIN AND EVOLUTION OF BASINS IN THE EASTERN PART OF JASŁO-SANOK DEPRESSION (POLISH CARPATHIANS) IN THE LATE VISTULIAN AND HOLOCENE Tadeusz Gerlach†1, Piotr Gębica2*, Kazimierz Szczepanek3, Dorota Nalepka4, Adam Walanus5 1 Department of Geomorphology and Hydrology of Mountains and Uplands, Polish Academy of Sciences, 31-018 Kraków, ul. Św. Jana 22, Poland 2 University of Rzeszów, Institute of Archaeology, 35-015 Rzeszów, Moniuszki 10, Poland; e-mail: [email protected] 3 Institute of Botany, Jagiellonian University, 31-501 Kraków, Kopernika 27, Poland 4 W. Szafer Institute of Botany, Polish Academy of Sciences, 31-512 Kraków, Lubicz 46, Poland; e-mail: [email protected] 5 Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, 30-059 Kraków, al. A. Mickiewicza 33, Poland; e-mail: [email protected] * corresponding author Abstract: Results of a geomorphologic study as well as radiocarbon and pollen analyses of sediments in small basins of the Jasło-Sanok Depression (Western Carpathians) are summarised. Floors of these basins, carved in soft shale-sandstone Krosno Beds, are covered with channel fluvial deposits and oxbow-lake sediments with lake chalk and peat accumu- lated in the Late Vistulian and Holocene. Since the early Atlantic Phase (ca 8,400–7,900 BP) the apparent acceleration of overbank (flood) deposition intermitting the peat accumulation is observed. The plant succession includes the Late Glacial (pre-Allerød, Allerød and Younger Dryas) with coniferous park forests, through mixed deciduous forests of the Holocene with elm, hazel, oak and lime as well as spruce-elm forests with alder in wetlands, up to present-day hornbeam forests (Tilio-Carpinetum of various types) and extra-zonal Carpathian beech forests (Dentario-Glandulosae- Fagetum). Abies alba (fir) is frequent in both these association types. First evidences of synanthropic plants that prove presence of prehistoric man appeared in the Subboreal Phase. The oldest radiocarbon date 13,550±100 BP (Gd-7355) [16,710–16,085 b2k], from a bottom part of the Humniska section is probably overestimated. This is indicated by pal- ynological data, which suggest attribution of this section to the older Allerød. Small thickness of gravel blanket from the Plenivistulian termination and the beginning of the Late Vistulian, as well as large areas devoid of weathering and solifluction covers indicate that during the Plenivistulian weathering processes and removal of silt-clay material pre- dominated in the basins. In that time the deflation was among important processes, which is proved by deflation troughs, faceted cobbles and thick covers of the Carpathian type of loess. The Besko Basin has pre-Vistulian tectonic foundation, while landforms of its floor are of erosion-degradation origin and formed during the last Scandinavian glaciation. In the Holocene the basin floors were overbuilt with fluvial deposits up to 8 m thick. Key words: deflation basins, radiocarbon dating, pollen analysis, Jasło-Sanok Depression, Carpathians Manuscript received 5 April 2019 accepted 16 May 2019 INTRODUCTION Among the areas in Central Europe that were intensively shaped by NW winds (blowing between Carpathians and Carpathians and surrounding basins, located during Alps) during the Pleistocene was the Pannonian Basin in Last Glacial Maximum (MIS 2) in the periglacial zone, Hungary, where yardangs, ventifacts, deflation depres- were exposed for an active wind action. In particular, sions and wind-blown sands, developed in periglacial wind erosion and deflation played important role in land- conditions (Sebe et al., 2011). Similar deflation landforms scape modelling of basins and foothills in the areas built of small depressions and closed basins occur in the in- of rocks less resistant to weathering and denudation. tra-mountainous Jasło-Sanok Depression (Doły Jasielsko- 172 T. GERLACH et al. o o o 21°E 22°E 23°E 16 20 24 300 376 Wisła Wisłok B Rzeszów A C Tarnów 50°N 54o IV 50°N Wisłoka LGM 18 300 STRZY San Mał a CIĘŻKOWICE ŻÓW Przemyśl Strona HUMNISKA FoothillsT Foothills o R 52 Gorlice JasłoK Krosno Nowy S ącz Sanok Dunajec BZ BESKID NISKI Mts 50o V BIESZCZADY 15 5 6 7 8 16 Dukla Pass Stebnica Tylicz Pass 280 San 16o 20o 24o 0 100 km Łupków Pass Turzepole Mts Leluta Jasionów 21°E 22°E 49°N 49°N 23°E 300 294 318 1 2 3 4 Górecki 123 4 5 6 III 337 1 7 8 91011 12 Górki 368 Trześniów 13 14 15 16 284 331 Wzdów Bzianka Wisłok Zmiennica 300 BUCZYNA FOREST 402 Posada Tafle Jaćmierska Milcza II Pielnica Wierzbiny 224 S17 284 2 1 I Zagony S22 R1 N BESKO 283 3 305 W5/1 291 375 4 Zapowiedź Zarszyn Wisłok 341 369 395 328 01km Mymoń Nowosielce Fig. 1. A. Location of the study area and last ice-sheet maximum limit (LGM – Last Glacial Maximum). B. Location of the studied basins on the map of the Jasło-Sanok Depression and the key sites: R – Roztoki, T – Tarnowiec, K – Kępa, BZ – Besko-Zapowiedź; explanation of symbols; 1 – northern extent of the Carpathians, 2 – boundary of the Jasło-Sanok Depression, 3 – study area, 4 – sites quoted in the text. C. Geomorphologic map of the Besko Basin, Jasionów and Humniska Basin (prepared based on a manuscript map of Tadeusz Gerlach, 1:50 000). Explanation of symbols: 1 – hill ridges and passes, 2 – flattenings within the hill ridges, 3 – slopes, 4 – foothills, 5 – terrace with loess cover deposited in the Warthanian (Saalian) Glaciation (Haczów terrace level), 6 – gravel terrace deposited in the Warthanian (Saalian) Glaciation, 7 – Vistulian terrace, 8 – floodplain (Holocene), 9 – denudational hummocks, 10 – alluvial fans, 11 – erosional V-shaped valleys, 12 – erosional edges, 13 – Wisłok River gap near Besko, 14 – river, creak and stream channels, 15 – artificial embankments, 16 – geological cross-sections (transects). ORIGIN AND EVOLUTION OF BASINS IN THE EASTERN PART OF JASŁO-SANOK DEPRESSION 173 Sanockie) in the Polish Flysh Carpathians (Gerlach et al., objective was to recognize source area of thick silt covers 1972; Gerlach, 1990). that occur in the southern part of the Dynów Foothills The Jasło-Sanok Depression is composed of flat ba- and in the Jasło-Sanok Depression. Unfortunately, he could sins at 250–360 m a.s.l. It is 20 km wide and 100 km long, not complete the materials due to his health condition. and separates the mountain range of the Beskid Low Mts. Consequently, the co-authors compiled his materials and (Beskid Niski) from the Strzyżów and Dynów Foothills supplemented them particularly with the paleobotanic anal- (Fig. 1A, B). This zone is characterised by a relief with yses and absolute datings. low foothills and vast Pleistocene terraces 30–80 m high. Its substratum is built of steeply dipping and relatively soft (easily eroded) strata of the Krosno Beds of the tectonic OVERVIEW OF RESEARCH depressions named the Central Carpathian Synclinorium (Świdziński, 1953). The Jasło-Sanok Depression represents Different hypotheses on origin and age of sediments an erosional-denudational basin, but distinctly lower ele- filling the listed above basins were postulated. According vation of denudational levels in the depression when com- to Klimaszewski (1948, 1967) the basin floors are formed pared with the Foothills and Beskid Low Mts., suggests tec- of sediments of the Vistulian age (terrace level III), over- tonic lowering of this area during the Quaternary (Fleszar, built by the Holocene fluvial deposits. Klimaszewski’s hy- 1914; Starkel, 1972; Zuchiewicz, 1987). The Beskid Low pothesis was questioned by Koperowa (1970), who – based Mts., which is ca 100 km long and 500–900 m a.s.l. high, on a palynological analysis of 9 m long depositional se- represent the narrowest and lowest segment (Dukla Pass quence at Besko-Zapowiedź – proved that the upper two at 500 m a.s.l.) of the whole Carpathian range. It is a wide third of the sequence in the southern part of the Besko morphologic gate, which favours occurrence of strong fun- Basin is of the Holocene age, while only the lower part neled south winds that erode soil on the windward southern represents the Late Vistulian. Publications of Koperowa slopes during winter and deposit snow and clay-silt-sand and Starkel (1972) as well as of Ralska-Jasiewiczowa and material on the leeward (northern) slopes (Gerlach, 1977; Starkel (1975), supplemented the study of the sequence Gerlach et al., 1986). In turn, in the area of the Jasło- from the Besko-Zapowiedź site with radiocarbon datings Sanok Depression the greatest number in the Carpathians of peat at depth of 5.75–6.50 m. The age of the bottom sam- (several dozen) of oval, closed basins and troughs occur, ple ranged 9,530±150 BP (Bln-1148) [11,250–10,450 b2k], which are palaeo-lakes filled up with the Late Vistulian and whereas the age of the top one was 7,900±100 BP (Bln- Holocene organic sediments (Klimaszewski, 1948; Gerlach 1147) [9,040–8,540 b2k]. Fluvial and lacustrine sediments, et al., 1972; Gerlach, 1990; Wójcik, 1987, 2003). In the 3 m thick, in the bottom part of the sequence represents the central part of the Jasło-Sanok Depression Gerlach (1990) Late Vistulian, while overbank fluvial deposits, 6 m thick, documented occurrence of more than 10 palaeo-lake basins belong to various phases of the Holocene. Pollen grains of with predominantly N-S elongation, fusiform hills (ridges) synanthropic plants, found in the middle part of the section of the same orientation and occurrence of ventifacts be- at depth of ca 5.5 m, confirm presence of prehistoric man tween the basins, which prove formation of these basins in the Subboreal Phase, 5,000–4,500 BP in the vicinity of as deflation (wind-carved) hollows and troughs, eroded the site.