Meliatic blueschists and their detritus in Cretaceous sediments: new data constraining tectonic evolution of the West Carpathians

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Abstract
The Western Carpathian Meliata Superunit (Meliaticum) includes a heterogeneous group of units—the blueschist-facies Bôrka Nappe and the very low-grade chaotic complexes—polygenous mélange containing material derived from various tectonic settings (Jaklovce Unit) and Jurassic oceanic sediments with olistostrome bodies (Meliata Unit s.s.). The high pressure/low temperature (HP/LT) metamorphism, development of tectonic mélanges and synorogenic sediments took place simultaneously during the Middle–Late Jurassic in connection with closing of the Meliata Ocean. We present some new data concerning composition of variegated mélanges related to the subduction–accretion processes of the Meliata Ocean and its continental margins. The polygenous mélange contains a mixture of fragments of HP/LT up to unmetamorphosed sedimentary and volcanic rocks, including blueschist-facies radiolarites. New electron microprobe chemical age data of monazites from metasediments of the Bôrka Nappe cluster in two peaks—earliest Cretaceous ages are interpreted in terms of post-exhumation, renewed burial during formation of the Meliatic accretionary wedge. The mid-Cretaceous ages might record the thermal relaxation during the thick-skinned nappe stacking and exhumation of the neighbouring Veporic metamorphic dome. In addition, we describe two distinct types of tourmalines and epidotes occurring in the Bôrka blueschists that document the prograde HP and retrograde LP metamorphic events. Detritus of the blueschist-facies rocks appears for the first time in the heavy mineral spectra of the Barremian–Aptian platform limestones. These limestones occur as clasts, together with glaucophanite pebbles, in the Albian–Cenomanian flysch formations of the Pieniny Klippen Belt (Klape Unit). We also review occurrences of other blueschist and ophiolitic erosional products in Cretaceous clastic formations and suggest that all have a Meliatic provenance.
Funding Information
  • Agentúra na Podporu Výskumu a Vývoja (APVV-0212-12)
  • Agentúra na Podporu Výskumu a Vývoja (APVV-0170-17)
  • Vedecká Grantová Agentúra MŠVVaŠ SR a SAV (1/0085/17)
  • Vedecká Grantová Agentúra MŠVVaŠ SR a SAV (2/0034/16)

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