No oil no interest? New Insights from Structural Geology and Thermochronology into the Western Polish Outer Carpathians

The Western Polish Outer Carpathian Thrust-fold Belt is in comparison to the Eastern Polish Carpathians deprived in geologic and thermochronologic data, likely as its prospect potential has been considered limited; new efforts by both industry and academia my change this. We present first results of a study that aims for a new cross section that integrates prior and new seismic, borehole, field-mapping, structural, thermal, and thermochronologic data. Preliminary, we find that the onset of thrust-related exhumation in the Magura and Silesian nappes started in the Eocene. Two younger exhumation episodes may have occurred in the early and late Miocene. We did not find evidence for mid-late Miocene convergence-parallel (~N‒S) extension (extensional collapse of the Carpathian thrust stack) in the Western Polish Outer Carpathians, the possible dominant factor for the rejuvenation of apatite fission-track ages in the Eastern Polish Outer Carpathians. Two alternative scenarios may apply: the Miocene exhumation episode may result from (i) underplating of the Magura nappe by an antiformal stack of the Dukla nappe, (ii) tectonic denudation in the footwall of large-scale, seismically-proven normal faults that formed in response to the arc-parallel extension, (iii) a combination of both, acting more or less contemporaneously.

Key words: Carpathians, apatite-fission-track thermochronology, brittle fault tectonics