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Minerals
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Geology and Petrology of Ophiolites
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Geology and Petrology of Ophiolites

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (11 September 2020) | Viewed by 12136

Special Issue Editor

Dr. Eugene Sklyarov

E-Mail Website
Guest Editor
Siberian Branch of the Russian Academy of Sciences, Institute of the Earth’s Crust, 128 Lermontov st., 664033 Irkutsk, Russia
Interests: tectonics; petrology of magmatic and metamorphic complexes; mineralogy

Special Issue Information

Dear Colleagues,

Ophiolites represent fragments of the upper mantle and oceanic crust that were incorporated into continental margins during continent–continent and arc-continent collisions, ridge-trench interactions, and/or subduction-accretion events. Ophiolite units (peridotite, gabbro, subvolcanic, and volcanic complexes) have varying internal structures, geochemical affinities, and age ranges, and can become tectonically juxtaposed in collision zones. They originally formed in different geodynamic settings, including continental margins, mid-ocean ridges, and suprasubduction zones. Incorporated into subduction-accretion complexes of active margins and later into orogenic belts, ophiolites may be highly dismembered, may have diverse lithological assemblages, metamorphic grades, styles of deformation, and geochemical affinities. Although ophiolite structure, geochemical affinities, and emplacement mechanisms have been debated for several decades, new data on previously studied and newly found ophiolite complexes all over the world may provide better understanding of magmatic processes in oceanic settings and the evolution of orogenic belts.

This Special Issue accepts original research and reviews related to the geology, geochemistry, mineralogy, and ore potential of various types of ophiolites in orogenic belts of various ages.

Dr. Eugene Sklyarov
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Ophiolite
  • Peridotite
  • Gabbro
  • Volcanic rocks
  • Geochemistry
  • Mineralogy
  • Mechanism of emplacement

Published Papers (3 papers)

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Research

36 pages, 14515 KiB  
Article
Geochemistry and Geochronology of the Neoproterozoic Backarc Basin Khzama Ophiolite (Anti-Atlas Mountains, Morocco): Tectonomagmatic Implications
by Latifa Chaib, Abdelhak Ait Lahna, Hassan Admou, Nasrrddine Youbi, Warda El Moume, Colombo Celso Gaeta Tassinari, João Mata, Miguel Angelo Stipp Basei, Kei Sato, Andrea Marzoli, Jean-Louis Bodinier, Andreas Gärtner, Moulay Ahmed Boumehdi, Mohamed Khalil Bensalah, Abderrahmane Soulaimani, Kevin Hefferan, Lhou Maacha and Amine Bajddi
Minerals 2021, 11(1), 56; https://doi.org/10.3390/min11010056 - 09 Jan 2021
Cited by 4 | Viewed by 5312
Abstract
The Khzama ophiolite is a highly dismembered complex located in the Siroua inlier of the Moroccan Anti-Atlas Belt. It consists of ultramafic rocks, cumulate gabbros, sheeted dikes, pillow lavas, and an overlying volcano-sedimentary sequence. Three main tectonic slices of sheeted dike complexes are [...] Read more.
The Khzama ophiolite is a highly dismembered complex located in the Siroua inlier of the Moroccan Anti-Atlas Belt. It consists of ultramafic rocks, cumulate gabbros, sheeted dikes, pillow lavas, and an overlying volcano-sedimentary sequence. Three main tectonic slices of sheeted dike complexes are studied in detail along three rivers, exposing well preserved outcrops where individual dikes are clearly distinguishable from the intruded host rock (Assif n’Tinzla, Assif n’Tasriwine, and Assif n’Iriri). Sheeted dikes of the Khzama ophiolitic complex are basaltic to andesitic in composition, displaying a clear sub-alkaline nature. We identify two sets of dikes that originate from lower High-Ti series (HTS) lavas and overlying upper Low-Ti series (LTS) lava. The immobile trace-element signatures of these rocks point to a genesis on a backarc environment with magmas sourced in a supra-subduction zone (SSZ) at the spinel peridotite zone. The obtained SHRIMP U-Pb data of the gabbro represent the first radiometric age of zircon extracted from the mafic rocks that were intruded by the sheeted dike complex of the Khzama ophiolite. These grains yield a concordia age of 763 ± 5 Ma, which is consistent with the 761.1 + 1.9/−1.6 and 762 + 1/−2 Ma U-Pb zircon ages of plagiogranites of Siroua. Based on their mineralogy, modal proportions, and major element chemistry, the felsic dikes are classified as high silica–low alumina trondhjemites or plagiogranites. These plagiogranites were likely formed by the partial melting of mafic rocks rather than by extreme fractional crystallization. A plagiogranite dated at 777 ± 4.7 Ma (U-Pb on zircon) is significantly older than the ca. 762 Ma plagiogranites previously recorded for the Khzama locality, suggesting a long-lived supra-subduction zone (SSZ) with conditions for the hydrous melting of mafic rocks. Full article
(This article belongs to the Special Issue Geology and Petrology of Ophiolites)
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34 pages, 12681 KiB  
Article
Early Cretaceous Plume–Ridge Interaction Recorded in the Band-e-Zeyarat Ophiolite (North Makran, Iran): New Constraints from Petrological, Mineral Chemistry, and Geochronological Data
by Edoardo Barbero, Morteza Delavari, Ashgar Dolati, Leila Vahedi, Antonio Langone, Michele Marroni, Luca Pandolfi, Federica Zaccarini and Emilio Saccani
Minerals 2020, 10(12), 1100; https://doi.org/10.3390/min10121100 - 07 Dec 2020
Cited by 12 | Viewed by 2904
Abstract
The North Makran domain (southeast Iran) is part of the Makran accretionary wedge and consists of an imbricate stack of continental and Neo-Tethyan oceanic tectonic units. Among these, the Band-e-Zeyarat ophiolite consists of (from bottom to top): ultramafic cumulates, layered gabbros, isotropic gabbros, [...] Read more.
The North Makran domain (southeast Iran) is part of the Makran accretionary wedge and consists of an imbricate stack of continental and Neo-Tethyan oceanic tectonic units. Among these, the Band-e-Zeyarat ophiolite consists of (from bottom to top): ultramafic cumulates, layered gabbros, isotropic gabbros, a sheeted dyke complex, and a volcanic sequence. Sheeted dykes and volcanic rocks are mainly represented by basalts and minor andesites and rhyolites showing either normal-type (N) or enriched-type (E) mid-ocean ridge basalt affinities (MORB). These conclusions are also supported by mineral chemistry data. In addition, E-MORBs can be subdivided in distinct subtypes based on slightly different but significant light rare earth elements, Th, Nb, TiO2, and Ta contents. These chemical differences point out for different partial melting conditions of their mantle sources, in terms of source composition, partial melting degrees, and melting depths. U-Pb geochronological data on zircons from intrusive rocks gave ages ranging from 122 to 129 Ma. We suggest that the Band-e-Zeyarat ophiolite represents an Early Cretaceous chemical composite oceanic crust formed in a mid-ocean ridge setting by partial melting of a depleted suboceanic mantle variably metasomatized by plume-type components. This ophiolite records, therefore, an Early Cretaceous plume–ridge interaction in the Makran Neo-Tethys. Full article
(This article belongs to the Special Issue Geology and Petrology of Ophiolites)
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22 pages, 9867 KiB  
Article
Dismembered Ophiolite of the Olkhon Composite Terrane (Baikal, Russia): Petrology and Emplacement
by Eugene V. Sklyarov, Angrey V. Lavrenchuk, Valentine S. Fedorovsky, Evgenii V. Pushkarev, Dina V. Semenova and Anastasia E. Starikova
Minerals 2020, 10(4), 305; https://doi.org/10.3390/min10040305 - 30 Mar 2020
Cited by 8 | Viewed by 2709
Abstract
Dismembered ophiolites in the Early Paleozoic Olkhon terrane, a part of the Baikal collisional belt in the southern periphery of the Siberian craton, occur as fault-bounded blocks of ultramafic and mafic rocks from a few meters to hundreds of meters in size. The [...] Read more.
Dismembered ophiolites in the Early Paleozoic Olkhon terrane, a part of the Baikal collisional belt in the southern periphery of the Siberian craton, occur as fault-bounded blocks of ultramafic and mafic rocks from a few meters to hundreds of meters in size. The ultramafic rocks are mainly dunite–harzburgite peridotites with gradual transitions between the lithologies, as well as moderate amounts of enstatitite, wehrlite, and clinopyroxenite, but no lherzolite. Most peridotites have strongly depleted chemistry and a mineralogy corresponding to the harzburgite type usual for ophiolites of suprasubduction zones (SSZ). The mafic rocks are leuco- to melanocratic gabbros with different relative percentages of clinopyroxene, olivine, and plagioclase, which enclose thin layers and lenses of clinopyroxenite and anorthosite. They bear back-arc basin geochemical signatures, a setting inferred for the Neoproterozoic southern Siberian craton. The gabbroic rocks are of two geochemical groups; most of their trace-element patterns show Ta-Nb minimums and Sr maximums common to suprasubduction zone ophiolites. Judging by the Ol + Opx + Chl + Chr mineral assemblages, the Olkhon peridotites underwent low amphibolite and amphibolite regional metamorphism at 500–650 °C. The occurrence of the ultramafic and mafic bodies is consistent with formation in an accretionary wedge metamorphosed during a collisional orogeny. The mantle and crustal parts of the Olkhon ophiolite suite apparently were incorporated into the terrane during the frontal collision of perio-oceanic structures with the Siberian craton. Then, in a later oblique collision event, they became dismembered by strike-slip faulting into relatively small bodies and fault blocks exposed in the present erosional surface. Full article
(This article belongs to the Special Issue Geology and Petrology of Ophiolites)
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