Mapa geologiczno-strukturalna podłoża miocenu przedgórza Karpat Polskich

Barbara Jabłońska, Adam Łapinkiewicz, Władysław Moryc

Abstrakt


GEOLOGICAL-STRUCTURAL MAP OF MIOCENE BASEMENT IN THE FORELAND OF THE POLISH CARPATHIANS

Summary
The basement of the Miocene in the Carpathian foreland was mapped in the scales 1: 50,000 and 1: 100,000. The paper presents a highly simplified version of the map in the scale 1 : 1,000,000 (Fig. 1 ), which fails to show several structural and geological elements traceable in the above mentioned ones.
The general structural pattern of the foreland is characterized by gradual plunging of the Miocene basement to the south, down to the depth of 4,000-4,500 m according to seismic data. The surface is cut by numerous Miocene faults as well as older ones, not rejuvenated in the Miocene but well traceable in deep-seated seismic reflectors.
The structural image of pre-Miocene erosional surface is characterized by presence of erosional furrows, especially in the zone between Cracow and Dębica. The furrows (Dziewin, Szczurowa, Żukowice, Brzeźnica) are presumably related to paleovalleys of pre-Miocene rivers. In the Carpathian foreland the erosional surface is formed of rocks ranging in age from the Precambrian to Upper Cretaceous, inclusively. In eastern part of, the foreland, the Precambrian is represented by phyllites (metaargillites), and in Miocene basement in western Polish Carpathians - by crystalline and metamorphic rocks. The Cambrian is known from the Lubaczów region (NE part of the foreland), where it is represented by shaly-sandy rocks and quartzites. Drillings made in the Żywiec (Lachowice) region in western part of the area showed that the Devonian is underlain by conglomerate assigned to the Lower Paleozoic because of the lack of biostratigraphic record. Ordovician and Silurian rocks were recorded beneath the Miocene in NE part of the foreland (Uszkowce in the Lubaczów region and Cmolas east of Mielec) only. Devonian and Lower Carboniferous rocks, mainly developed in carbonate facies, were found beneath the Miocene at two limbs of Upper Paleozoic cover: NE limb (Mielec-Rzeszów) and SW and S limb, traced south of Myślenice and Bielsko-Cieszyn areas. Distribution of the Upper Carboniferous is limited to western part of the foreland and the cover found between Myślenice and Bielsko and in the Cieszyn region (both in Poland and Czechoslovakia), represents south-eastem extension of that of the Upper Silesian Coal Basin. The Permian does not crop out at the sub-Miocene surface in the Carpathian foreland.
Triassic rocks are known from both external part of the foreland (Middle and Upper Triassic of the Mielec-Rzeszów region) and the vicinities of Myślenice (Buntsandstein from Jachówka). The marginal erosional zones also display Middle and Upper (but not Lower) Jurassic and Cretaceous rocks. The latter form a vast cover in central part of the foreland. The cover, strongly affected by erosion (especially in valleys of pre-Miocene rivers), is , built of Upper Cretaceous rocks assigned to two complexes: an older one (Cenomanian-Coniacian), and younger, transgressive (Santonian-Lower Maastrichtian). Moreover, Lower Cretaceous rocks are also known from a narrow zone in the vicinities of Lubaczów (Basznia-Babczyn area), and the Upper Cretaceous - from the Lublin region. The geological-cross-section (Fig. 2) shows tectonic- structural pattern of strata building the Carpathian foreland and those of the Flysch Carpathians, overthrusted from the south on the former.

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