Serie glacigeniczne i kopalne doliny rzeczne środkowego plejstocenu w rejonie Kocka

Abstract

Podano charakterystykę osadów plejstoceńskich starszych od zlodowacenia środkowopolskiego, poprzedzoną analizą podłoża plejstocenu. W obrębie omawianych osadów plejstocenu wyróżniono dwie serie glacigeniczne odpowiadające zlodowaceniu krakowskiemu oraz dwie generacje kopalnych dolin rzecznych, z których starsze wiążą się interstadiałem zlodowacenia krakowskiego, a młodsze z interglacjałem wielkim. GLACIGENIC SERIES AND BURIED RIVER VALLEYS OF MIDDLE-PLEISTOCENE AGE IN KOCK REGIONThe Pleistocene series older than Middle Polish (Riss) Glaciation are characterized in the paper on the basis of boring material mainly (Figs. 1, 2). The characteristics is preceded by the analysis of the relief of substratum of Quaternary deposits (Figs. 3, 4). Within the mentioned Pleistocene series there are distinguished two glacigenic horizons corresponding to the Cracovian (Mindel) Glaciation, and two generations of buried river valleys – the older ones corresponding to the interstadial of the Cracovian Glaciation, and the younger ones being of Great Interglacial age.The Cracovian Glaciation was the oldest one on the examined territory, covering usually Tertiary deposits. It was two-fold here (Figs. 6A, 6B). The older stadial was evidently “weaker”, while the younger one caused strong glacitectonic deformations, followed by glacigenic deposition of considerable thickness (e. g. Fig. 6D). The latter one represented most probably the stadial of the maximum extent of the ice-sheet. The glacigenic series of the discussed glaciation fill glacitectonic depressions in particular zones (Figs. 6E, 6D). The localization of these depressions depends on the configuration of consolidated Cretaceous rocks underlying soft Tertiary deposits disturbed by glacitectonic processes (Figs. 3 and 4); compare also H. Ruszczyńska-Szenajch, 1976. In some places buried lake basins occur within glacitectonic depressions. The origin of the basins is closely connected with the origin of the depressions (H. Ruszczyńska-Szenajch, 1978).The interstadial river valleys (Fig. 5) cut through the older glacigenic series of the Cracovian Glaciation and the underyling Tertiary deposits to a depth exceeding in some places 30 m. They are filled with fluvial deposits accumulated in one sedimentation cycle (Fig. 6C). In southern part of the discussed area the deposits are covered with sediments accumulated in ice-dammed lakes, which were formed due to damming the rivers by advancing ice-sheet of the younger stadial, which in turn covered the whole series with glacial deposits.The valleys of the Great Interglacial represent a well developed river system (Fig. 7), with downward cutting (through the above quoted series) reaching about 30 m. They are filled with deposits accumulated in two cycles of fluvial sedimentation (Fig. 6E), and they are covered with fluvioglacial and ice-dammed series, which corresponds already to the advance of ice-sheet of the next (Middle Polish, Riss) glaciation, which overrode the whole area and accumulated here glacial deposits.