Sm-Nd geochronology and petrologic investigation of sub-ophiolite metamorphic sole from the Dinarides (Krivaja-Konjuh, Ophiolite Complex, Bosnia and Herzegovina)

Scientific paper - Original scientific paper

• Author: Branimir Šegvić
• Author: Damir Slovenec
• Author: Ralf Schuster
• Author: Elvir Babajić
• Author: Luka Badurina
• Author: Boško. Lugović
• Author's institution: Croatian Geological Survey
• Author's institution: University of Zagreb; Faculty of Mining, Geology and Petroleum Engineering; (Department of Mineralogy, Petrology and Mineral Resources)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geology

Abstract (english)

The Dinaridic segment of Neotethys was affected by a widespread shortening and related subduction-accretion-obduction processes that commenced in the middle Jurassic. In the Dinarides, the Krivaja-Konjuh Ophiolite Complex (KKOC) stands as the largest ophiolite complex with a well-exposed metamorphic sole which is the key to understanding the dynamics of intraoceanic subduction initiation in this part of Neotethys. In this contribution we present Sm-Nd geochronology on a granulite facies amphibolite from the KKOC, as well as a detailed petrological description. A five-point isochrone age calculated from clinopyroxene, plagioclase, garnet, amphibole and whole rock is 162 ± 14 Ma (MSWD = 6.2), whereas garnet and whole rock yield 160 ± 7 Ma. Ages calculated from all data points except clinopyroxene are 162 ± 5 Ma (MSWD = 1.09). Petrographic investigations suggest that these ages date granulite facies metamorphic conditions (i.e. peak metamorphism of Grt-Cpx amphibolite) rather than post-peak exhumation or obduction processes. Phase textural relationships are in line with previous research, which indicated a peak metamorphism equilibration pressure and temperature of ~1 GPa and ~800 °C, respectively. Granulite facies conditions are elucidated for an igneous precursor, which underwent a multi-stage metamorphism that gave rise to recrystallization of igneous clinopyroxene and plagioclase, epitaxial growth of amphibole, and garnet blastosis. Taking into account the age of gabbronorite from the youngest segment of the KKOC oceanic crust (Taorcian to Bathonian) and ages of radiolarian assemblages from the KKOC mélange (Bajocian to Bathonian), it may be inferred that within ~25 Ma the Dinaridic segment of Neotethys evolved rapidly from active ridge
spreading through a stage of intraoceanic subduction and arc magmatism toward sub-ophiolite exhumation and further obduction along the Adria passive margin at the end of the Jurassic era.

• Keywords (english): Dinarides; Sm-Nd ages; high-grade metamorphic sole; Neotethys closure; Jurassic ophiolites
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Geologia Croatica
• Numbering: vol. 73, no. 2, pp. 119-130
• p-ISSN: 1330-030X
• e-ISSN: 1333-4875
• DOI: https://doi.org/10.4154/gc.2020.09
• URN:NBN: urn:nbn:hr:169:807110
• Publication: 2020-06-24
• Project: Number: IP-2019-04-3824; Title (croatian): Vulkano-sedimentne sukcesije sjeverozapadne Hrvatske i njihova uloga u razumijevanju geodinamike Paleotetisa tijekom srednjeg trijasa; Title (english): Revealing the Middle Triassic Paleotethyan geodynamics recorded in the volcano-sedimentary successions of NW Croatia; Acronym: GOST; Leader: Damir Slovenec; Jurisdiction: Croatia; Funding stream: Research Projects
• Project: Number: 195-1951126-3205; Title (croatian): Tektonomagmatska korelacija fragmentirane oceanske litosfere u Dinaridima; Title (english): Tectonomagmatic Correlation of Fragmented Oceanic Lithosphere in the Dinarides; Leader: Marta Mileusnić; Jurisdiction: Croatia; Funding stream: zProjects
• Document URL: http://www.geologia-croatica.hr/index.php/GC/article/view/996/1836
• Type of resource: Text
• Access conditions: Open access
• Created on: 2025-02-28 13:44:53