Evolution of the Sibişel Shear Zone (South Carpathians): A study of its type locality near Răşinari (Romania) and tectonic implications

Mihai N Ducea, Elena Negulescu, Lucia Profeta, Gavril Săbău, Denisa Jianu, Lucian Petrescu, Derek Hoffman

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The Sibişel Shear Zone is a 1–3 km wide, ductile shear zone located in the South Carpathian Mountains, Romania. In the Rășinari area, the ductile shear zone juxtaposes amphibolite facies rocks of the Lotru Metamorphic Suite against greenschist facies rocks of the Râuşorul Cisnădioarei Formation. The first represents the eroded remnants of Peri-Gondwanan arcs formed between the Neoproterozoic-Silurian (650–430 Ma), regionally metamorphosed to amphibolite facies during the Variscan orogeny (350–320 Ma). The second is composed of metasedimentary and metavolcanic Neoproterozoic-Ordovician (700–497 Ma) assemblages of mafic to intermediate bulk composition also resembling an island arc metamorphosed during the Ordovician (prior to ~ 463 Ma). Between these lie the epidote amphibolite facies mylonitic and ultramylonitic rocks of the Sibișel Formation, a tectonic mélange dominated by mafic actinolite schists attenuated into a high strain ductile shear zone. Mineral Rb-Sr isochrons document the time of juxtaposition of the three domains during the Permian to Early Triassic (~290–240 Ma). Ductile shear sense indicators suggest a right lateral transpressive mechanism of juxtaposition; the Sibişel shear zone is a remnant Permo-Triassic suture between two Early Paleozoic Gondwanan terranes. A zircon and apatite U-Th/He age transect across the shear zone yields Alpine ages (54–90 Ma apatite and 98–122 Ma zircon); these data demonstrate that the exposed rocks were not subjected to Alpine ductile deformation. Our results have significant implications for the assembly of Gondwanan terranes and their docking to Baltica during Pangea's formation. Arc terranes free of Variscan metamorphism existed until the Early Triassic, emphasizing the complex tectonics of terrane amalgamation during the closure of Paleotethys.

Original languageEnglish (US)
Pages (from-to)2131-2157
Number of pages27
JournalTectonics
Volume35
Issue number9
DOIs
StatePublished - Sep 1 2016

Fingerprint

Romania
type locality
Tectonics
shear zone
tectonics
Rocks
shear
Apatites
terrane
amphibolite facies
rocks
Triassic
Hercynian orogeny
rock
apatite
apatites
Ordovician
zircon
Carpathian Mountains (Europe)
Minerals

Keywords

  • ductile shear
  • geochronology
  • Paleotethys
  • Permo-Triassic
  • South Carpathians

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Cite this

Evolution of the Sibişel Shear Zone (South Carpathians) : A study of its type locality near Răşinari (Romania) and tectonic implications. / Ducea, Mihai N; Negulescu, Elena; Profeta, Lucia; Săbău, Gavril; Jianu, Denisa; Petrescu, Lucian; Hoffman, Derek.

In: Tectonics, Vol. 35, No. 9, 01.09.2016, p. 2131-2157.

Research output: Contribution to journalArticle

Ducea, Mihai N ; Negulescu, Elena ; Profeta, Lucia ; Săbău, Gavril ; Jianu, Denisa ; Petrescu, Lucian ; Hoffman, Derek. / Evolution of the Sibişel Shear Zone (South Carpathians) : A study of its type locality near Răşinari (Romania) and tectonic implications. In: Tectonics. 2016 ; Vol. 35, No. 9. pp. 2131-2157.
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