Compositional fingerprints of chromian spinel from the refractory chrome ores of Metalleion, Othris (Greece): Implications for metallogeny and deformation of chromitites within a 'hot' oceanic fault zone
Uloženo v:
| Název: | Compositional fingerprints of chromian spinel from the refractory chrome ores of Metalleion, Othris (Greece): Implications for metallogeny and deformation of chromitites within a 'hot' oceanic fault zone |
|---|---|
| Autoři: | Kapsiotis, Argyrios, Rassios, Anne Ewing, Uysal, Ibrahim, Grieco, Giovanni, Akmaz, Recep Melih, Saka, Samet, Bussolesi, Micol |
| Zdroj: | Journal of Geochemical Exploration. 185:14-32 |
| Informace o vydavateli: | Elsevier BV, 2018. |
| Rok vydání: | 2018 |
| Témata: | 01 natural sciences, 0105 earth and related environmental sciences, chromian spinel (Cr-spinel), chromitite, Greece, laser-ablation ICP-MS, ophiolite, othris, geochemistry and petrology, economic geology, Chromian spinel (Cr-spinel), Chromitite, Laser-ablation ICP-MS, Ophiolite, Othris |
| Popis: | The chrome ores of the retired Metalleion mine of the Othris ophiolite are hosted in a small volume of a pervasively serpentinized, tabular harzburgite body. These ores have been studied to determine their geological mode of occurrence, mineralogy and chromian spinel (Cr-spinel) chemistry. The ores consist of massive chromitite (85–95% modal Cr-spinel) with mylonitic fabric in imbricate-shaped pods. Chromian spinel displays a limited range in Cr# [Cr/(Cr + Al) × 100 = 53–63] and Mg# [Mg/(Mg + Fe2 +) × 100 = 59–73] and low TiO2 content (≤ 0.11 wt%). Minor- (Ti, Ni, V, Mn and Zn) and trace-element (Sc, Co and Ga) concentrations do not show any significant variations from Cr-spinel cores to boundaries and were not considerably modified by post-magmatic processes. However, Cr-spinel compositions show slight enrichments in Zn and V, and depletions in Ti and Sc when compared to the composition of chromite from the East Pacific Rise mid-ocean ridge (MOR) basalts. The composition of Cr-spinel from the Metalleion chromitites is quite anomalous on a global perspective as these ores are not clearly associated to a suprasubduction zone (SSZ) or MOR chemistry. Field data indicate that the Metalleion chromitites lack remnant dunite envelopes due to prolonged shearing within the deforming harzburgite host and are constrained in location to a ductile-brittle shear zone that correlates with the transforming direction of the Domokos oceanic fault. Compositional data indicate that chromitites equilibrated with ambient harzburgite via a melt-peridotite interaction process followed by melt mixing. Geochemical calculations demonstrate that the parental magmas of the Metalleion chromitites had intermediate affinity between typical mid-ocean ridge basalts (MORB), island arc tholeiites (IAT) and boninites. We conclude that these melts originated within a hydrated and oxidized mantle wedge beneath an infant forearc basin connected by a transform fault to an active MOR. |
| Druh dokumentu: | Article |
| Popis souboru: | application/pdf |
| Jazyk: | English |
| ISSN: | 0375-6742 |
| DOI: | 10.1016/j.gexplo.2017.11.003 |
| Přístupová URL adresa: | https://www.sciencedirect.com/science/article/pii/S0375674217306222 https://hdl.handle.net/2434/554374 https://doi.org/10.1016/j.gexplo.2017.11.003 https://hdl.handle.net/10281/415842 https://doi.org/10.1016/j.gexplo.2017.11.003 https://hdl.handle.net/20.500.12628/24196 |
| Rights: | Elsevier TDM |
| Přístupové číslo: | edsair.doi.dedup.....aafa97be0653da55d4aa6b8319a8c50a |
| Databáze: | OpenAIRE |
Full Text Finder 
Nájsť tento článok vo Web of Science | Abstrakt: | The chrome ores of the retired Metalleion mine of the Othris ophiolite are hosted in a small volume of a pervasively serpentinized, tabular harzburgite body. These ores have been studied to determine their geological mode of occurrence, mineralogy and chromian spinel (Cr-spinel) chemistry. The ores consist of massive chromitite (85–95% modal Cr-spinel) with mylonitic fabric in imbricate-shaped pods. Chromian spinel displays a limited range in Cr# [Cr/(Cr + Al) × 100 = 53–63] and Mg# [Mg/(Mg + Fe2 +) × 100 = 59–73] and low TiO2 content (≤ 0.11 wt%). Minor- (Ti, Ni, V, Mn and Zn) and trace-element (Sc, Co and Ga) concentrations do not show any significant variations from Cr-spinel cores to boundaries and were not considerably modified by post-magmatic processes. However, Cr-spinel compositions show slight enrichments in Zn and V, and depletions in Ti and Sc when compared to the composition of chromite from the East Pacific Rise mid-ocean ridge (MOR) basalts. The composition of Cr-spinel from the Metalleion chromitites is quite anomalous on a global perspective as these ores are not clearly associated to a suprasubduction zone (SSZ) or MOR chemistry. Field data indicate that the Metalleion chromitites lack remnant dunite envelopes due to prolonged shearing within the deforming harzburgite host and are constrained in location to a ductile-brittle shear zone that correlates with the transforming direction of the Domokos oceanic fault. Compositional data indicate that chromitites equilibrated with ambient harzburgite via a melt-peridotite interaction process followed by melt mixing. Geochemical calculations demonstrate that the parental magmas of the Metalleion chromitites had intermediate affinity between typical mid-ocean ridge basalts (MORB), island arc tholeiites (IAT) and boninites. We conclude that these melts originated within a hydrated and oxidized mantle wedge beneath an infant forearc basin connected by a transform fault to an active MOR. |
|---|---|
| ISSN: | 03756742 |
| DOI: | 10.1016/j.gexplo.2017.11.003 |