Early Cretaceous Plume–Ridge Interaction Recorded in the Band-e-Zeyarat Ophiolite (North Makran, Iran): New Constraints from Petrological, Mineral Chemistry, and Geochronological Data

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, 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.

Petrogenesis and Tectonic Evolution of the Kahnouj Ophiolitic Complex (SE Iran): Constraints from geochemistry and Sr-Nd-Pb isotope composition

“…Several distinct tectonic settings including rifted island-arcs, back-arc basins, and fore-arc basins, have been suggested for the origin of the SSZ ophiolite (Kusky 2004 Our previous 40 Ar/ 39 Ar ages of coarse-grained gabbro and hornblende gabbro from the KOC indicate an age of 152.7 ± 5.1 Ma and 126.5 ± 1.6 Ma, respectively. These ages are similar to reported K/Ar ages by Kananian et Barbero et al (2020a) (122 to 129 Ma), implying that plagiogranites probably formed simultaneous with or after formation of the oceanic crustal ma c rocks (121 to 156 Ma). We argue that plagiogranite rocks formed by partial melting of gabbroic rocks (Ghasemi Siani et al 2021a, b).…”

“…Therefore, in this paper, we focus on whole-rock geochemistry of ma c and ultrama c rocks and Sr-Nd-Pb isotopic data. Our new results plus data from the literature (Kananian 2001;Ghazi et al 2004;Arvin et al 2005; Barbero et al 2020a) will assist in deciphering the petrogenesis and allow evaluation of the tectonic setting of KOC.…”

“…The Kahnouj ophiolitic complex (KOC) is one of the ophiolitic sequences in the northern ophiolite belt and could be considered as one of the crucial ophiolitic sequences of the Makran ophiolite zone. An enriched mid-ocean ridge (E-MORB) chemical a nity of KOC basalts was reported by Ghaze et al (2004) and Saccani et al (2018) in relation to mantle sources enriched by plume-type components, whereas both enriched mid-ocean ridge (E-MORB) and normal mid-ocean ridge (N-MORB) a nities were reported for basaltic rocks (Arvin et al 2005; Barbero et al 2020a). Our previous work showed that the KOC classi es as a supra-subduction zone (SSZ) formed in a back-arc basin environment (Ghasemi Siani et al 2021a, b).…”

Mineral Chemistry of Olivine, Oxy-Spinel, and Clinopyroxene in Lavas and Xenoliths from the Canary, Azores, and Cape Verde Islands (Macaronesia, North Atlantic Ocean): New Data and Comparisons with the Literature

“…All the analyzed clinopyroxenes show a negative correlation between Mg# and Ti apfu (Figure 11C). Clinopyroxene compositions are plotted in the TiO2-SiO2/100-Na2O ternary diagram [6,29], which correlates the mineral chemistry of clinopyroxene with the geodynamic formation setting (Figure 12A-F). The entire dataset shows a certain affinity with within Oceanic Plate basalts (WOPBs) and Iceland basalts (ICBs).…”

“…Similar to olivine, clinopyroxene appears in the early phase during the crystallization of mantle-derived magmas. Therefore, the composition of magmatic clinopyroxene in volcanic rocks records key information regarding the chemistry and evolution of the host lavas, the crystallization conditions, and the geodynamic settings in which the clinopyroxene and its host rock formed [4,6,27,29,30,55,76]. In particular, it has been suggested that the variation in clinopyroxene compositions can be related to differences in the primary composition of the parent magma rather than the physical conditions of crystallization [77].…”