Zlodowacenie północnopolskie Wysoczyzny Tureckiej w świetle nowych danych

Waldemar Gogołek, Alicja Mańkowska

Abstract


Na podstawie wyników badań palinologicznych, malakologicznych i wieku bezwzględnego (14C, TL) osadów jeziornych z dziewięciu stanowisk stwierdzono obecność lądolodu vistuliańskiego na Wysoczyźnie Tureckiej. W pięciu stanowiskach osady te znajdują się pod nadkładem glin zwałowych. Szczegółowe prace kartograficzne i analiza geomorfologiczna, poparte tymi wynikami, pozwoliły rozstrzygnąć dyskusję co do poligenezy makroform Wysoczyzny Tureckiej. Rzeźba zboczy masywu Złotych Gór, Wału Malanowskiego i Moren Tureckich jest pozostałością strefy marginalnej lądolodu vistuliańskiego.

VISTULIAN OF THE TUREK UPLAND IN THE LIGHT OF NEW DATA

Polygenetic hills of Złote Góry, Turek Moraines and Malanów Ridge rise 8O-100 m over Turek Upland. Their surface is considerably denudated and their slopes are raised due to hills, up to 20 m high which are typical of young postglacial landscape. The surrounding area is shaped like typical ice melting relief.

During detail cartographic investigations several sites of lacustrine deposits have been found also below the topmost glacial horizon. The following deposits have been examined in nine sites (Fig. 1): silts, fine-and medium-grained sands, peats, peaty washes and in places clays (Fig. 2). They are overlain with tills, fluviogiacial sands and gravels, and fluvial sands of the Main Stadial as well as with Holocene deposits. Eemian fluvial sands, tills, fluvioglacial and limnoglacial deposits of Middle Polish Glaciation form their substrate. Numerous paleosol horizons have been found below the Main Stadial of the Vistulian, and in places on Cle top of the lacustrine sequences (Fig. 1), They are composed of high cIayey or silty sands with admixture of humus.

Palynologic investigations have been carried out by Z. Borówko-Dłużakowa. In Grabowiec, Kiszewy and Milinów sites a two-phase succession of plants have been observed. The lower one is a mixed forest phase where spruce predominated, and the upper one is a pine-birchwillow phase. Both floras date back to the climate optimum of the same interglacial (interstadial?) as the Konin-Marantów flora (Brörup?) or to its declining period. The remaining sites represent only pine-birch phase succession. Due to malacologic investigations at Krągola site S. Skompski has found that lacustrine deposits at the depth of 2,5-3,0 m represent interglacial period, possibly its cool phase. Absolute age of peats and peaty washes has been determined on the basis of 14C dating, and TL method to silty sands. The results obtained by M. F. Pazdur at several sites are as follows: Grabowiec – 37 000 B.P. (14C), Kiszewy - 27 000 ± 1000 B.P. (14C), Wymysłów - 31 200 ± 800 B.P. (14C) under till cover, Żdżary (borehole 2) – 41 400 ± 3000 - 2200 B.P. (14C) under till cover, Młyńska – 29 000 ± 1200 B.P. (14C) under till cover, Żdżary (borehole 3) - 21 200 ± 2000-1600 B.P. (14C) under till cover, Małgów - 78 000 ± 20 000 B.P. (TL) under till cover.

The above data lend to the following conclusions:

1. Tills which cover lacustrine deposits belong to Main Stadia I (Leszno Phase) of Vistulian Glaciation.

2. Sedimentation in lacustrine deposits took place at least during one interstadial period of Vistulian (according to the results of palynologic investigations -during Brörup, and according to absolute age datings - during Hengelo, Moershoofd, Denekamp, up to Konin-Maliniec II interval).

3. Soil horizons formed during Vistulian interstadial periods.

4. Diversified relief of the slopes of Złote Góry hills and Malanów Ridge is a heritage of marginal zone of Leszno Phase. Both of them were elevated over the surface of the glacier.

5. In consequence of the existence of the glacier within Turek Upland during Leszno Phase, the range of the Vistulian should be situated some tens kilometers to the south of the today accepted limit.


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