Stanowisko interglacjalne w Losach koło Lubawy na Pojezierzu Mazurskim

Abstract

Przedstawiono dotychczasowe wyniki badań kopalnych osadów jeziornych stanowiska Losy w zachodniej części Pojezierza Mazurskiego. Na podstawie badań palinologicznych stwierdzono interglacjalny charakter flory, różnej od znanej z dotychczas zbadanych stanowisk czwartorzędowych na terenie Polski. Datowanie metodą termoluminescencji osadów podścielających (270 tys. lat BP) i przykrywają­cych (230 tys. lat BP) serir: jeziorną stanowiska Losy pozwala na usytuowanie wyróżnionego na jej pod-stawie interglacjału między zlodowaceniem Odry a Warty.

INTERGLACIAL SITE AT LOSY NEAR LUBAWA IN THE MAZURY LAKELAND

The paper presents the accessible results of geologic and palynologic investigations of ancient lake sediments from the Losy site near Lubawa in the Mazury Lakeland (Fig. 1). These sediments are com-posed of lake marl, to 16 m thick, underlain by sands (TL dating: 280,000 years BP) and overlain by stratified sands with gravels (TL dating: 230,000 years BP) and till (Fig. 2). The top series of the lake marl is intensively weathered and enriched in compounds of Fe³⁺ and Mn.

Palynologic investigations enabled to distinguish four phases of the vegetation development (Fig. 3): forest-tundra (I), birch forest with larch and then with elm, ash and willow (Il), mixed pine·oak forest with ash and elm (Ill), deciduous oak-ash forest with linden and then with hazel (IV). Such succession is undoubtedly of interglacial origin, quite different from other Quaternary floras known in the territory of Poland but also, from other compared floras of Central Europe.

A complete comparative floristic analysis is not possible yet as in the Losy section no lake sediments from interglacial climatic optimum and the post-optimal phases were noted. But there is no doubt that a considerable later entering of hazel than of linden and a very high content of larch and ash pollens, are the distinct differences between the studied succession and the one, typical for the Eemian Interglacial. Similarly, a diatom assemblage in sediments of the Losy site is also entirely different from the onc known for the Eemian Interglacial from the neighbouring Nidzica site (cf. I. Tuszyńska-Gruza, 1984). The distinguished floristic assemblages from the Losy site are also different from the ones ascribed to the Mazovian and Ferdynand6w interglacials (= Mindel/Riss).

Taking into account the probable differences of the pollen spectrum, resulting from geographic limits of individual trees, the interglacial flora from Losy can be paralleled with the flora of the Rugia Intetglacial, distinguished in German Democratic Republic. The thermoluminescence datings of the sediments from the Losy site allow to consider the rake section as representative for the interglacial period between the Odra (Riss I) and Warta (Riss Il) glaciations. From a chronostratigraphic point of view, it corresponds with the Lublin (Riss l/Riss JI) Interglacial (cf. A. Środoń, 1969; S.Z. Różycki, 1978).