Budowa frontalnej strefy Karpat zewnętrznych na przykładzie mioceńskiej jednostki Zgłobic w rejonie Brzeska–Wojnicza — nowe dane, nowe modele, nowe pytania
Abstract
The structure of the Outer Carpathian orogenic front: an example of the Miocene Zgłobice Unit between Brzesko and Wojnicz (SE Poland)— new data, new models, new questions.
S u m m a r y. Pilot interpretation of selected new seismic profiles located within the Miocene Zgłobice Unit (Polish Outer Carpathians, Brzesko–Wojnicz area) allowed us to set up a new tectonic model of the Carpathian front in this area, in many respects different from the previously proposed ones. The central part of the Zgłobice Unit is interpreted as a passive-roof duplex defining a Miocene triangle zone. Above the duplex, in the roof of the triangle zone, major synclinal folds are recognised in the Miocene deposits and attributed to shortening in the hanging wall of the frontal roof backthrust of the duplex. Some of the inferred tectonic structures are classified as syn-depositional, coeval with sedimentation of the upper portion of the post-evaporitic siliciclastic foredeep succession (Grabowiec Beds). Three main types of hydrocarbon traps are identified within the Zg³obice Unit and within the sedimentary infill of deep palaeovalleys developed within the Mesozoic basement. Because of pilot character of the interpretation here discussed, some of the solutions proposed in this paper should be regarded as working hypotheses, requiring further, more detailed studies. The latter should include detailed stratigraphic investigations in the key structural elements of the Zgłobice Unit, applying advanced techniques of seismic data processing (pre-stack depth migration, structural seismic modelling) and acquisition of shallow high-resolution seismic images. In order to better understand the geometry and kinematics of the interpreted linked thrust system, application of quantitative balancing techniques will be necessary.
S u m m a r y. Pilot interpretation of selected new seismic profiles located within the Miocene Zgłobice Unit (Polish Outer Carpathians, Brzesko–Wojnicz area) allowed us to set up a new tectonic model of the Carpathian front in this area, in many respects different from the previously proposed ones. The central part of the Zgłobice Unit is interpreted as a passive-roof duplex defining a Miocene triangle zone. Above the duplex, in the roof of the triangle zone, major synclinal folds are recognised in the Miocene deposits and attributed to shortening in the hanging wall of the frontal roof backthrust of the duplex. Some of the inferred tectonic structures are classified as syn-depositional, coeval with sedimentation of the upper portion of the post-evaporitic siliciclastic foredeep succession (Grabowiec Beds). Three main types of hydrocarbon traps are identified within the Zg³obice Unit and within the sedimentary infill of deep palaeovalleys developed within the Mesozoic basement. Because of pilot character of the interpretation here discussed, some of the solutions proposed in this paper should be regarded as working hypotheses, requiring further, more detailed studies. The latter should include detailed stratigraphic investigations in the key structural elements of the Zgłobice Unit, applying advanced techniques of seismic data processing (pre-stack depth migration, structural seismic modelling) and acquisition of shallow high-resolution seismic images. In order to better understand the geometry and kinematics of the interpreted linked thrust system, application of quantitative balancing techniques will be necessary.