Abstract
Pre-Mesozoic exotic crystalline blocks within the Outer Carpathian flysch have potential to unravel the nature of their eroded basement source(s) and to reconstruct the Paleozoic–Precambrian history of the Protocarpathians. Strongly tectonized Campanian–Maastrichtian grey marls in the Subsilesian Nappe of the Outer Western Carpathians in Poland contain a variety of different lithology types, including granitoids and andesites. Petrological investigations coupled with zircon and apatite U-Pb dating were performed on crystalline (subvolcanic) exotic blocks from a locality in the Subsilesian Nappe. U-Pb zircon dating yields magmatic crystallization ages of c. 293 Ma for the microgranitoid and c. 310 Ma for the andesite block, with inherited zircon cores yielding Archean, Paleoproterozoic, Mesoproterozoic and Cadomian ages. Whole rock trace element and Nd isotope data imply that the melt source was composed of a significant Neoproterozoic crustal component in both the microgranite and andesite. The Late Carboniferous–Permian magmatic activity likely continues outside the Carpathian Belt and can be linked to a Late Paleozoic transtensional zone, which is a continuation of the Lubliniec–Kraków Zone that extends under the Carpathians to Moesia. This Late Paleozoic transtensional zone was probably reactivated during the Late Cretaceous under a transpressional regime within the Żegocina tectonic zone, which caused the uplift of the Subsilesian Ridge and intensive erosion.
Highlights
The presence of Pre-Mesozoic basement within the Alpine orogens was first identified c. 200 years ago [1]
This paper investigates and interprets crystalline plutonic and volcanic exotic blocks, found at a locality in the Subsilesian Nappe of the Outer Western
Exotic blocks of Late Carboniferous–Permian magmatic rocks are found in Campanian–Maastrichtian grey marls of the Subsilesian Nappe
Summary
The presence of Pre-Mesozoic basement within the Alpine orogens was first identified c. 200 years ago [1]. In most of the Alpine orogens of Europe, such as the Alps and Carpathians, Pre-Mesozoic basement is present as exotic blocks inside the sedimentary or metasedimentary successions or as uplifted crystalline massifs, termed “core mountains” [2,3]. Pre-Alpine basement is present in the form of exotic blocks and interpreted as remnants of the Protocarpathian crystalline basement, which is inferred to underlay the Mesozoic and Cenozoic basins of the Carpathian orogenic system [4,5]. During the syn-orogenic (Cretaceous–Neogene) stage of the evolution of the Carpathians, several ridges were formed inside the Tethys marginal basins [6]. These ridges were cored by Pre-Mesozoic crystalline basement and were uplifted during Alpine closure of the Tethys Ocean. Subsequent erosion of the uplifted ridges resulted in the transportation of large amounts of basement material (often as olistostromes) into the Carpathian basins [7]
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