Ocena interglacjału z Ferdynandowa na tle ewolucji facjalnej osadów plejstoceńskich przedpola Wyżyny Lubelskiej

Abstract

Scharakteryzowano warunki sedymentacyjno-denudacyjne panujące w czasie plejstocenu na przedpolu Wyżyny Lubelskiej i na tym tle przeanalizowano zmiany facjalne osadów czwartorzędowych. Na podstawie profilów otworów wiertniczych wyróżniono dolinę kopalną, nazywając ją wilczańsko-ferdynandowską. W serii osadów plejstoceńskich, wypełniających tę dolinę, zwrócono uwagę na utwory interglacjalne, usytuowane na wysokości ok. 120-140 m n.p.m., między dwiema glinami zwałowymi. Na podstawie wyników badań petrograficzych i paleobotanicznych zaproponowano zmianę dotychczasowego oznaczenia stratygraficznego serii organicznej z Ferdynandowa, mianowicie zaliczono ją do interglacjału lubelskiego poprzedzającego zlodowacenie Warty (Lublinian i Warthian według A. Środonia, 1969). W takim ujęciu seria organogeniczna z Ferdynandowa uzyskuje rangę dokumentacyjną, przyczyniając się do wyjaśnienia problemu samodzielności zlodowacenia Warty, poprzedzonego charakterystycznym okresem interglacjalnym.THE ESTIMATION OF THE INTERGLACIAL FROM FERDYNANDÓW AT THE BACKGROUND OF FACIAL EVOLUTION OF PLEISTOCENE DEPOSITS FROM THE FOREFIELD OF THE LUBLIN UPLANDThe studies covered the area of so-called Ferdynandów post-glacial highland (Fig. 1) from the forefield of the Lublin Upland (eastern part of Central Poland). The analysis of Quaternary materials has supplied some new data on facial evolution of the deposits at the background of geomorphological and hydrographic changes and made possible drawing some stratigraphic conclusions which indicate  necessity of revision of stratigraphic position of the nterglacial deposits from Ferdynandów.The paleobotanic studies (Z. Janczyk-Kopikowa, 1975) have shown that the plant assemblage and climatic characteristics of the Interglacial from Ferdynandów are markedly different from those of other Interglacial deposits hitherto known. Z. Janczyk-Kopikowa has had great difficulties in attempts to correlate the data gathered with those concerning other Interglacial localities with the exception of the Szkłowski (Odincowski) Interglacial. The petrographic studies have shown that tills delineating the Interglacial deposits from below and above in the borehole Ferdynandów belong to the Mindel and Riss (J. E. Mojski, 1969; J. Rzechowski, 1966, 1967). Therefore it is not possible to assign the deposits to other than Mindel/lRiss Interglacial. Z. Janczyk-Kopikowa (1975) accepted such dating but she stated that a thorough analysis of current views on that Interglacial is required.The analysis of geological setting and paleogeography of this area from the Quaternary times, carried out by the present author, has given further support to the above mentioned individual paleobotanic character of the, Interglacial deposits from Ferdynandów.The forefield of the Lublin Upland between gorge sections of Vistula and Wieprz river valleys which comprises the Wilczanka-Ferdynandów highland, represents area especially suitable for tracing changes in facies of Pleistocene deposits at the background of hydrographic evolution. It was found that the conditions prevailing here were unsuitable for preservation of older Pleistocene deposits. Processes responsible for denudation of these deposits (including Mindel/Riss Interglacial deposits) were especially intense on the forefield of the Lublin Upland ,where they were adjusted to erosional base of Vistula and Wieprz gorge valleys. Erosional incisions reached here the level of 30 m a.s.l. The incisions became the site of sandy-silty accumulation during subsequent accumulation phases of the Mindel/Riss Interglacial (Fig. 3, 4, deposits No 4).The sedimentary series occurring above is connected with fluvioglacial and glacial accumulation from the Riss ,times hitherto considered as a single glacial period. However, undoubtful Interglacial horizon was found within this series at a relatively high level (120-140 m a.s.l.) at Fetdynandów (Fig. 3, 4, deposits No 7). The analysis of conditions of origin of 'these deposits has shown some hydrographic changes in drainage basins of pre-Wieprz and pre-Vistula rivers. Ancient valley from Ferdynandów area (Fig. 2) became situated at the watershed and its old river-beds formed lacustrinal basin. Successive phases of infilling of that basin are reconstructed in detail on the basis of results of lithological-mineralogical and paleobotanic studies. The latter have shown the existence of 6 climatic phases evidencing Interglacial character.An old trend to differentiate the Warta stage as a separate Glaciation, first put forward by P. Woldstedt in 1927, obtained further support in the form of results of studies on Interglacial deposits from Ferdynandów. This is in accordance with the point of view of A. Środon (19'69) who placed the Interglacial series of the Lublin Upland below the Warts Glaciation. This was made with the reference to the Szkłowski Interglacial. This Interglacial also considered similar to the Interglacial from Ferdynand6w by Z. Janczyk-Kopikowa, is delineated from above by the Moscow Glaciation (corresponding to the Warta Glaciation) and from below - by the Dneper Glaciation (corresponding to the Riss Glaciation).The Intergiacial deposits of the Ferdynandów type were also revealed by a drilling made at neigbouring village Poznań (Fig. 3) and they crop out at Podlodów upon Wieprz river (Fig. 4). They are overlied by a series of glacial, fluvioglacial and moraine deposits of a successive, Warta Glaciation. In result of that accumulation the ancient Ferdynandów valley became completely obscure.During the Eemian Interglacial the Wieprz drainage basin was catched by the Vistula river from the west. In this way a latitudinal Wieprz valley originated on foundations of marginal valley from recessional phases of the Warta Glaciation. Northern steep escarpment of the valley, 40 m higland incised in the Ferdynandów highland, makes it possible to analyse Pleistocene structure of the highland.To sum up, the spatial ·analysis of facial evolution of Pleistocene deposits of the forefield of the Lublin Upland as well as original results of paleobotanic studies on the interglacial from Ferdynandów made possible to propose a stratigraphic correction of the Riss Glaciation. A separate Warta (Warthian according to A. Środon) Glacjation is distinguished. This Glaciation is preceded by the Lublin (or Lublinian according to A. Środon) lnterglacial which comprises the Interglacial series from Ferdynandów.