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

Šegvić, Branimir; Slovenec, Damir; Schuster, Ralf; Babajić, Elvir; Badurina, Luka; Lugović, Boško

doi:10.4154/gc.2020.09

Cited by 8 publications

(4 citation statements)

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“…Such an amphibolite (sample BN-14-4A) remained spatially associated with its protolith (sample BN-14-4B), as shown in Figure 3, and was exhumated and obducted on the Adria continental margin. Comparison of the amphibolites studied here with well investigated metamorphic sole amphibolites of Krivaja-Konjuh ophiolite complex (Šegvić et al, 2019;Šegvić et al, 2020;Balen and Massonne, 2021) revealed remarkable similarities between them. Krivaja-Konjuh ophiolite complex is situated ~ 280 km to the east of Banovina ophiolite complex in central Bosnia and Herzegovina and represents the biggest ultramafic exposure in the Dinarides (Šegvić et al, 2019).…”

Section: Origin Of the Metamorphic Sole Amphibolite In Banovina Ophio...mentioning

confidence: 63%

Geochemistry and Petrography of Metamorphic Sole Amphibolites From the Slatina Quarry, Mt. Zrinska Gora, Croatia

Putak Juriček,

Garašić

2024

MGPB

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The investigated Mt. Zrinska Gora amphibolites are a part of the metamorphic sole of the Banovina ophiolite complex. Mineral composition and other petrographic characteristics of amphibolites and adjacent peridotite were investigated by polarised microscopy and chemical analyses of rocks were obtained by a combination of inductively coupled plasma mass and emission spectrometry. The main minerals in these garnet-bearing amphibolites are amphibole and plagioclase with accessory garnet, sphene, spinel, opaque mineral ± clinopyroxene ± quartz ± actinolite ± zoisite-clinozoisite ± prehnite ± pumpelyite and ± clay minerals. Kelyphitic corona is developed around garnet. The amphibolites have nematoblastic, nematogranoblastic, porphyroblastic and porphyroclastic textures and homogenous to foliated structures. The presence of clinopyroxene in some of the investigated amphibolites points to their possible formation under P‒T conditions of upper amphibolite facies. The greenschist facies retrograde metamorphism and subsequent surface weathering of amphibolites is also evident. The chemical composition of rocks indicates that protoliths of most amphibolites were tholeiitic basalts, initially formed in island arcs and the adjoining back-arc basins. During the intraoceanic subduction in Jurassic Neotethys Ocean basalts/basaltic tuffs of island arc tholeiite affinity and back-arc basin basalts, positioned on the top of the down-going oceanic slab, were welded to the base of the hot over-riding mantle wedge, metamorphosed to amphibolite rocks and obducted together with ophiolites on the Adria continental margine. The new described amphibolite type having peridotite protolith characteristics originated as the consequence of the hydration of the bottom part of the overlying mantle wedge.

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Section: Origin Of the Metamorphic Sole Amphibolite In Banovina Ophio...mentioning

confidence: 63%

Geochemistry and Petrography of Metamorphic Sole Amphibolites From the Slatina Quarry, Mt. Zrinska Gora, Croatia

Putak Juriček,

Garašić

2024

MGPB

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“…A plausible explanation may be the lack of deep normal faulting that channelizes fluid flows to deeper crustal levels (e.g. Schiffman & Staudigel, 1994), possibly as a result of rapid transitions in the Dinaridic Neotethys geotectonic setting, changing from active ridge magmatism to an intraoceanic subduction environment and island-arc volcanism (Slovenec et al 2011; Šegvić et al 2014). Finally, petrographic and EMPA/SEM observations yielded no evidence of alteration of hydrothermal phases formed in ophiolite and non-ophiolite basalts/andesites and tuffs, which is consistent with the closed hydrothermal system hypothesis advocated above (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…According to these authors, the formation of the mélange took place during Middle–Late Jurassic to Early Cretaceous time. This is the period of rapid transition of the Dinaridic branch of Neotethys, which evolved from an active ridge magmatism to an intraoceanic subduction environment and island/back-arc volcanism (Šegvić et al 2014). The sedimentary component of the mélange is made up of Triassic and Jurassic sandstone and chert as well as Lower Cretaceous limestone and clastic rocks.…”

Section: Geological Settingmentioning

confidence: 99%

Major and rare earth element mineral chemistry of low-grade assemblages inform dynamics of hydrothermal ocean-floor metamorphism in the Dinaridic Neotethys

Šegvić

Slovenec²,

Badurina³

2022

Geol. Mag.

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This contribution provides insights into ocean-floor hydrothermal metamorphism of the fast-evolving Dinaridic Neotethys. Mineralogical, geochemical and Sr isotope data collected from altered ophiolites and non-ophiolite basalts/andesites and tuffs of the active continental margin are consistent with hydrothermal alteration trajectories that reflect the host-rock composition. This suggests that hydrothermal fluxes were restricted within a simple closed seawater-fed system. Based on the initial isotopic ratios of Sr, two fluid–rock interaction trends are established: (a) low-to-medium degrees of metasomatism in pre-Middle Jurassic anorogenic ophiolites that progressively abated, and (b) increased intensities of metasomatism in post-Middle Jurassic orogenic ophiolites. This agrees with chlorite thermometry and Ca-Al-(Fe)-silicate phase chemistry. The metamorphic assemblages belong to the zeolite, prehnite-pumpellyite, prehnite-actinolite and greenschist facies. The facies is reliant on the temperature of hydrothermal systems and their fluid chemistry. Rare earth element (REE) phase geochemistry shows (a) variable fluid–rock ratios in chlorite and pumpellyite dependent on fluid temperatures, (b) prominent Eu and Ce anomalies that reflect the fluid oxidation state, (c) light REE/heavy REE mobilization attributed to prevalent ligand complexation, and (d) multi-phase fluid percolation across reaction zones of heterogeneous permeability. This study proposes initiation of simple hydrothermal system(s) at or near a spreading centre(s) in the infancy of the Dinaridic Neotethys. Such a system became more complex during Middle Jurassic and Early Cretaceous time with reactive hydrothermal fluids passing the recharge area and reaching the hot reaction zone. An abrupt obliteration of the established high-temperature regime ensued, following the final closure of the Neotethys.

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“…The Ozren ophiolite complex (OOC) in Bosnia and Herzegovina is part of the Dinaridic Ophiolite Belt [8,[10][11][12][13][14][15][16][17][18][19][20][21][22][23]. This complex shows a polystage mantle evolution and revealed an almost complete ophiolitic cross-section composed of peridotites, plagioclase peridotites, plagiogranites, troctolites, and other gabbros, gabbroic, doleritic, and fewer basaltic dykes.…”

Section: Geological Settingmentioning

confidence: 99%

Amphibole Group Minerals in the Ozren Massif Ophiolites of Bosnia and Herzegovina as Petrogenetic Indicators

Ustalić,

Nemec,

Milovská

et al. 2024

Minerals

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The Ozren ophiolite complex (OOC) of the Dinaridic Ophiolite Belt is one of the six ophiolite complexes in Bosnia and Herzegovina. This paper deals with the mineral chemistry of amphiboles determined by electron probe micro-analysis and micro-Raman spectroscopy. The detected amphibole generations and types in mafic, ultramafic, and metamorphic rocks suggest a polystage evolution and are therefore useful petrogenetic indicators of the investigated OOC. Most gabbroic rocks and dolerites contain primary magmatic amphibole1 (magnesio-hornblende to pargasite, occasionally hastingsite) and prismatic to needle-like aggregates of late magmatic amphibole2 (magnesio-hornblende), while plagiogranite contains ferri-winchite and ferro-ferri-winchite as primary magmatic amphibole. Post-magmatic amphiboles were detected in dolerites, troctolites, and lesser in peridotites. The Na-(Ti)-rich amphibole3 (ferri-winchite and ferro-ferri-winchite to katophorite and ferri-katophorite) with amphibole4 (grunerite) rim formed along the grain boundaries of clinopyroxene, amphibole1, and plagioclase in dolerites. A part of these amphiboles grows into amphibole1, 2. Kaersutite to ferri-kaersutite, associated with phlogopite, occur in troctolites and dunites, while Mhbl was detected in harzburgite. The ultramafic rocks (lherzolites, harzburgites, and dunites) and the gabbroic layer are crosscut by clinopyroxene–plagioclase gabbroic and clinopyroxene–plagioclase–amphibole gabbro–dolerite dykes, suggesting ‘dry’ and ‘hydrated’ percolating melts generated in inferred subridge and supra-subduction settings, respectively. The amphibole3 and 4 in gabbros and dolerites and similar amphibole types in ultramafic rocks could be related to inferred arc-type basaltic and plagiogranitic percolating melts and fluids. Low-Al amphibole5 (tremolite and actinolite) and associated chlorite, albite, and clinozoisite represent the ocean-floor alterations in mafic rocks. Amphibole6 (magnesio-hornblende to pargasite) was identified in metamorphic sole amphibolites. Micro-Raman spectroscopy provided typical Raman spectra for the studied amphiboles, highlighting distinct features such as bands related to CMg content, CFe3+ presence, TO4 ring-breathing mode, TiO6 stretching mode, presence > 0.3 apfu of CTi, and TO4 stretching indicating CFe2+ in the structure. Applied amphibole geothermobarometry revealed the formation P–T conditions of amphibole (Amp)1 (avg. 863 °C at 0.23 GPa), Amp2 (avg. 747 °C at 0.17 GPa), Amp in the mantle rocks (avg. 853 °C at 0.64 GPa), Amp5 (avg. 349 °C at 0.03 GPa), and Amp6 (avg. 694 °C at 0.46 GPa).

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

Cited by 8 publications

References 0 publications

Geochemistry and Petrography of Metamorphic Sole Amphibolites From the Slatina Quarry, Mt. Zrinska Gora, Croatia

Geochemistry and Petrography of Metamorphic Sole Amphibolites From the Slatina Quarry, Mt. Zrinska Gora, Croatia

Major and rare earth element mineral chemistry of low-grade assemblages inform dynamics of hydrothermal ocean-floor metamorphism in the Dinaridic Neotethys

Amphibole Group Minerals in the Ozren Massif Ophiolites of Bosnia and Herzegovina as Petrogenetic Indicators

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