Wykształcenie górnej części utworów miocenu i czwartorzędu w zapadlisku przedkarpackim między Krakowem a Tarnowem

Abstract

 Omówiono górną część utworów miocenu zapadliska przedkarpackiego należących do dolnego i górnego badenu oraz dolnego sarmatu. Są to osady bardzo słabo zróżnicowane litologicznie. Udało się jednak dokonać ich podziału litologicznego na 5 kompleksów zróżnicowanych na podstawie zawartości piaskowców i łupków. Utwory miocenu spoczywają niezgodnie na podłożu prekambryjskim i paleozoiczno-mezozoicznym.

ON THE DEVELOPMENT OF UPPER PART OF MIOCENE AND QUATERNARY DEPOSITS IN THE CARPATIDAN FOREDEEP BETWEEN CRACOW AND TARNÓW

Miocene deposits resting on Precambrian and Paleozoic-Mesozoic basement in the Carpathian Foredeep, are characterized with reference to well logs and lithological analysis of core material. The Miocene section comprises Lower and Upper Badenian and Lower Sarmatian deposits weakly varying in lithology. In the vertical section, there are differentiated five complexes:

Complex I – the lowermost, developed in the facies of shales and mudstones with sandstone intercalations, stratigraphically corresponding to the Sub-anhydrite Beds.

Complex II – represented primarily by anhydrites partly with gypsum and shaly intercalations; anhydrites are intercalated by rock salts in the neighbourhood of the Carpathians.

The complexes I and II fairly well reflect morphology of basement surface which is emphasized by varying thickness and, locally, complete lack of the deposits. Stratigraphically, they comprise Lower Badenian. The complexes III–V occur in the Supra-anhydrite Series of the section.

Complex HI is represented by shales, claystones and mudstones, locally sandy. Stratigraphically, it represents Upper Badenian and some parts of Lower Sarmatian.

Complex IV is characterized by fairly large share of sandy deposits and marked facies changes.

The sedimentation of the Miocene ended with deposits of complex V.

Complex V comprises shales, mudstones and sandstones and, in its uppermost part, sands and weakly cohesive sandstones intercalated by mudstone packets. Detailed studies of that of the section made possible accurate differentiation of sandstone and clay-mudstone depoists. Thickness of sandstones is varying from some tens to over 350 m, generally increasing eastwards. Table 1 shows the characteristics of the sandstones, and maps (Figs. 2–6) and geological cross-sections (Figs. 7, 8) – spatial distribution of lithological series. The sandy complex of deposits is overlain by the Quaternary, varying from about 10 to 50 m in thickness (Fig. 1).

Quaternary bedrock surface is dipping northwards from the margin of the Carpathians and it is weakly differentiated in morphology. Furrow-like depressions, clearly marked here, are interpreted as ancient valleys of the Vistula, Dunajec and Raba rivers (Fig. 2).

The complex of sandy deposits, distributed throughout the region, is interpreted as important aquifer of fresh and very weakly mineralized water, despite of medium reservoir properties. The possibilities of supply of water at some definite contacts of Quaternary and Miocene deposits is emphasized.