Formation of chromitites and ferrogabbros in ultramafic and mafic members of the Variscan Ślęża ophiolite (SW Poland)

Wojtulek, Piotr; Schulz, Bernhard; Delura, Katarzyna; Dajek, Michał

doi:10.1016/j.oregeorev.2019.01.021

Cited by 12 publications

(9 citation statements)

References 56 publications

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“…Application of the deposit-type classification scheme of Dupuis and Beaudoin [67] to the examined rocks from Kletno shows that, despite the high Cu content of one hornblendite sample (KL-1 = 173.7 ppm Cu) and magmatic origin of its protolith, the examined prospect does not correspond with the magmatic Ni-Cu massive sulfide deposit-type ( Figure 13A), which is consistent with the low Ni content of hornblendites (62-66 ppm Ni). Magnetite from hornblendites classify it as high temperature magmatic Fe-Ti and V deposits ( Figure 13B,C), similar to the case of the Fe-Ti-V mineralization hosted in the metabasites of theŚlęża Ophiolite [17]. In addition, Fe-Ti-V mineralization hosted in dolomite veins also plots in the field of magmatic Fe-Ti, V deposits ( Figure 13B,C).…”

Section: Mineralization Origin and The Fluid Sourcesupporting

confidence: 56%

Origin of Talc and Fe-Ti-V Mineralization in the Kletno Deposit (the Śnieżnik Massif, SW Poland)

et al. 2019

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The Kletno deposit in theŚnieżnik Massif (Central Sudetes, SW Poland), mined for Fe, U, Ag, Cu, fluorite, and marble through the ages, developed at the contact of marbles and orthogneiss. Here, we present a new Fe-Ti-V-ore (containing up to 14.07 wt. % Fe, 2.05 wt. % Ti, and 2055 ppm V in bulk rock) and ornamental-to gem-quality talc prospect at the southwest margin of this deposit. This newly documented Fe-Ti-V mineralization is hosted in hornblendites, dolomite veins, and chlorite schists, which, along with talc, envelopes a tectonic slice of serpentinite. Hornblendites are interpreted as metamorphosed ferrogabbros, derived from the same mafic melts as adjacent barren metagabbros. The oxygen and carbon isotope compositions of metabasites and dolomite veins (amphibole δ 18 O values = 8.8-9.3% ; carbonate δ 18 O values = 12.8-16.0% , and δ 13 C values = −8.3% to −7.2% ), in combination with those of the country marbles (carbonate δ 18 O and δ 13 C values = 23.2% and +0.1% , respectively), suggest that mineralization-bearing hornblendites formed due to interaction of the mafic magma with CO 2 released during the decarbonation of the sediments. The CO 2 -bearing fluid interaction with gabbros likely caused carbonation of the gabbros and formation of the dolomite veins, whereas talc formed due to Si-rich fluids, possibly derived from a mafic intrusion, interaction with serpentinite, or due to the metasomatism of the serpentinite-gabbro assemblage. Moreover, fluids leaching Fe and Ti from the adjacent sediments can mix with the mafic magma causing enrichment of the magma in Fe and Ti. Consequently, the mineralization-bearing ferrogabbros became even more enriched in Fe and Ti, which can be linked with the formation of Fe-Ti-V ore bodies.

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Section: Mineralization Origin and The Fluid Sourcesupporting

confidence: 56%

Origin of Talc and Fe-Ti-V Mineralization in the Kletno Deposit (the Śnieżnik Massif, SW Poland)

et al. 2019

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“…These EDX spectra have characteristic peaks at distinct positions in the keV scale and distinct relative cts/s, allowing identification of the major elements present and providing a semiquantitative indication of their concentrations. The SEM-MLA software (version MLA 3.1 by FEI) recognizes each mineral phase after its EDX spectrum by comparison to a reference set of EDX spectra from identified mineral phases with known compositions [7,8]. The mode of recognition is straightforward for phases larger than several microns, but this is not always the case for the rhyolitic matrix.…”

Section: Mineral Liberation Analysesmentioning

confidence: 99%

“…Automated SEM analysis provides precise information on modal compositions, including the identification of many accessory phases [8,9]. However, it is the additional information such as grain size distribution and mineral association that offer better insight into the possible sources of zircon grains.…”

Section: New Insights Into Zircon Behavior In Silicic Magmas Based Onmentioning

confidence: 99%

“…So far, automated Scanning Electron Microscope Mineral Liberation Analysis (SEM-MLA) has been applied in the industry for solving problems of ore mineral processing and extraction [7]. However, there are other assets of automated SEM methodology, including the detailed modal analysis of different rocks [8,9] or quantification of environmental weathering [10,11]. The great asset of automated SEM analyses is that they do not only calculate modal proportions, but also provide detailed quantitative information on grain size distribution, mineral associations, and phase characteristics such as angularity or length/breadth ratio.…”

Section: Introductionmentioning

confidence: 99%

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Towards Identification of Zircon Populations in Permo-Carboniferous Rhyolites of Central Europe: Insight from Automated SEM-Mineral Liberation Analyses

et al. 2020

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Zircon is a main mineral used for dating rhyolitic magmas as well as reconstructing their differentiation. It is common that different populations of zircon grains occur in a single rhyolitic sample. The presence of both autocrystic and antecrystic zircon grains is reflected in their strongly varied chemical compositions and slight spread of ages. However, postmagmatic processes may induce lead loss, which is also recorded as a spread of zircon ages. Therefore, new approaches to identify different zircon populations in rhyolitic rocks are needed. In this study, we suggest that detailed examination of zircon positions in the thin sections of rhyolitic rocks provides valuable information on zircon sources that can be used to identify autocrystic and antecrystic zircon populations. Automated Scanning Electron Microscope (SEM) analyses are of great applicability in determining this, as they return both qualitative and quantitative information and allow for quick comparisons between different rhyolite localities. Five localities of Permo-Carboniferous rhyolites related to post-Variscan extension in Central Europe (Organy, Bieberstein, Halle, Chemnitz, Krucze) were analyzed by automated SEM (MLA-SEM). The samples covered a range of Zr whole rock contents and displayed both crystalline and glassy groundmass. Surprisingly, each locality seemed to have its own special zircon fingerprint. Based on comparisons of whole rocks, modal composition and SEM images Chemnitz ignimbrite was interpreted as containing mostly (or fully) antecrystic zircon, whereas the Bieberstein dyke was shown to possibly contain both types, with the antecrystic zircon being associated with disturbed cumulates. On the other hand, Organy was probably dominated by autocrystic zircon, and Krucze contained dismembered, subhedral zircon in its matrix, whereas Halle zircon was located partly in late veins, filling cracks in laccolith. Both localities may, therefore, contain zircon populations that represent later stages than the crystallization of the main rhyolitic body.

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“…The dates show a relatively large spread of c. 10 Ma and, importantly, the more reliable results come from the biggest Ślęża Massif only; the age of the other component massifs of the CSO is less well constrained. Also, the well-defined mid-ocean-ridge-basalt (MORB) -like affinities of the mafic rocks in the CSO are in contrast with supra-subduction characteristics found in some rodingites, ore bodies and epidosites (Dubińska & Gunia, 1997;Wojtulek et al 2016aWojtulek et al , b, 2017Wojtulek et al , 2019Klukowski, 2017). This raises the question of geotectonic interpretation of the CSO.…”

Section: Introductionmentioning

confidence: 99%

The Central Sudetic Ophiolite (European Variscan Belt): precise U–Pb zircon dating and geotectonic implications

et al. 2020

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Precise U–Pb zircon dating using the chemical abrasion – isotope dilution – thermal ionization mass spectrometry (CA-ID-TIMS) method constrains the age of the Central Sudetic Ophiolite (CSO) in the Variscan Belt of Europe. A felsic gabbro from the Ślęża Massif contains zircon xenocrysts dated at 404.8 ± 0.3 Ma and younger crystals dated at 402.6 ± 0.2 Ma that determine the final crystallization age of the gabbro. An identical age of 402.7 ± 0.3 Ma was determined for plagiogranite from the Nowa Ruda–Słupiec Massif, and plagiogranite from the Braszowice–Brzeźnica Massif yields a similar, but less reliable, age of > 401.2 Ma. The different massifs in the CSO are therefore considered as tectonically dismembered fragments of a single oceanic domain formed at c. 402.6–402.7 Ma (Early Devonian – Emsian). The magmatic activity recorded in the CSO was contemporaneous with the high-temperature/high-pressure metamorphism of granulites and peridotites in the Góry Sowie Massif, separating dismembered parts of the CSO. This suggests geodynamic coupling between the continental subduction recorded in the Góry Sowie and the oceanic spreading recorded in the CSO. Regional geological data indicate that the CSO was obducted before c. 383 Ma, less than 20 Ma after its formation at an oceanic spreading centre. The CSO is shown to be one of the oldest and first obducted among the Devonian ophiolites of the Variscan Belt. The CSO probably originated in an evolved back-arc basin in which the influence of subduction-related fluids and melts increased with time, from negligible during the formation of predominant mid-ocean-ridge-type magmatic rocks to strong at later stages, when rodingites, epidosites and other minor lithologies formed.

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Formation of chromitites and ferrogabbros in ultramafic and mafic members of the Variscan Ślęża ophiolite (SW Poland)

Cited by 12 publications

References 56 publications

Origin of Talc and Fe-Ti-V Mineralization in the Kletno Deposit (the Śnieżnik Massif, SW Poland)

Origin of Talc and Fe-Ti-V Mineralization in the Kletno Deposit (the Śnieżnik Massif, SW Poland)

Towards Identification of Zircon Populations in Permo-Carboniferous Rhyolites of Central Europe: Insight from Automated SEM-Mineral Liberation Analyses

The Central Sudetic Ophiolite (European Variscan Belt): precise U–Pb zircon dating and geotectonic implications

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