hide
Free keywords:
Zircon dating, Zircon chemistry, Proto-Rheic Ocean, Qaidam Ocean, Cenerian Orogeny, CentralWestern Carpathians
Abstract:
Zircon petrochronology from amphibolites and retrogressed eclogites from the basement of the Western Tatra
Mountains (CentralWestern Carpathians) reveals a complex rock evolution. An island-arc related basaltic amphibolite
from Žiarska Valley shows three distinct zircon forming events: igneous zircon growth at ca. 498 Ma
(Middle/Late Cambrian) and two phases of amphibolite-facies metamorphism at ca. 470 Ma (Early Ordovician)
and at ca. 344 Ma (Early Carboniferous). A retrogressed eclogite from Baranèc Mountain records two zircon forming events: metamorphic zircon growth under eclogite-facies conditions at ca. 367 Ma (Late Devonian) and amphibolite-facies metamorphism at ca. 349 Ma (Early Carboniferous). These data contribute towards understanding and correlating major tectonothermal events that shaped the eastern margin of Gondwana in the
Early Palaeozoic and its subsequent Variscan evolution. The metabasites record vestiges of two completely independent
oceanic domains preserved within the Central Western Carpathians: (1) An Ediacaran to Cambrian oceanic
arc related to the proto-Rheic - Qaidam oceans and metamorphosed to amphibolite-facies in the Early
Ordovician subduction of the proto-Rheic - Qaidam arc during the Cenerian orogeny (ca. 470 Ma) and (2) Late
Devonian oceanic crust related to a back-arc basin (Pernek-type), formed by the opening of the Paleotethys
and metamorphosed to eclogite-facies during Devonian subduction (ca. 367 Ma). The common Variscan and
later evolution of these oceanic remnants commenced with amphibolite-facies metamorphic overprinting in
the Early Carboniferous (amphibolite: ca. 344Ma; retrogressed eclogite: ca. 349Ma) related to an Early Variscan
consolidation and the formation of Pangea. None of the investigated rocks of the Central Western Carpathians
show any evidence of being chronologically or palaeogeographically related to the Rheic Ocean, therefore any
prolongation of the Rheic suture from the Sudetes into the Alpine-Carpathian realm is highly problematic. Instead,
the Southern and Central Alpine Cenerian orogeny can be traced into the CentralWestern Carpathians.
