H. Rahbari; N. A. Rashidnejad Omran; M. Khalatbari-Jafari
Abstract
As a part of Takab Metamorphic Complex (TMC), Belqeis Mountain has a variety of metamorphic rocks including orthogneiss, pelitic schists, meta-ultramafics and mafic rocks and dolomitic marbles. This complex was metamorphosed, faulted and folded during Late Neoproterozoic-Early Cambrian ...
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As a part of Takab Metamorphic Complex (TMC), Belqeis Mountain has a variety of metamorphic rocks including orthogneiss, pelitic schists, meta-ultramafics and mafic rocks and dolomitic marbles. This complex was metamorphosed, faulted and folded during Late Neoproterozoic-Early Cambrian Pan-African orogeny and invaded by granitoid pertinent to the subduction of the Neo-Tethys oceanic crust beneath the Iranian crust during Tertiary. Geochemically, the protolith of orthogneiss of Belqeis Mountain is high K and has calc-alkaline affinity and both fractional crystallization and magma mixing have been incorporated significantly to produce the protolith of them. The pattern of trace elements normalized to chondrite and primitive mantle points to enrichment in LILE and LREE, depletion of HFSE and HREE and shows negative anomalies in Eu, Ba, Nb, Sr, Ti and P. Depletion in HFSE was accompanied with enrichment of LILEs and LREEs indicating the generation of protolith in subduction setting related to active continental margins. Tectonic discrimination diagrams suggest a combination of volcanic arc and continental collision settings for the studied samples. There are many evidence including La/Nb>1 and relatively high values of several ratios such as Zr/Nb (14.7), Th/Nb (1.5), Ba/Nb (58), La/Nb (3), Ti/Zr (14.9), Nb/Ce (0.24) and (La/Sm)n (3.76),close to crust values, confirming that mantle was not incorporated solely but both crust and mantle sources were contributed in origin of these rocks. All aforementioned points in addition to occurrence of paleo-suture zone and ophiolitic rocks (i.e. serpentinites, meta-mafic and meta-ultramafic rocks) around these medium to high grade metamorphic rocks confirm that subduction of an oceanic lithosphere followed by collision in the study area.
M. Khalatbari Jafari; H. Sepehr
Abstract
The Kahduiyeh tectonized Ophiolite exposed at the extreme northern part of Dehshir-Baft Ophiolite belt in the southern margin of centeral Iran microcontinent, comprise of mantle peridotites and crustal sequence. The serpentinized peridotites have cpx- bearing harzhburgite and lherzholite compositions ...
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The Kahduiyeh tectonized Ophiolite exposed at the extreme northern part of Dehshir-Baft Ophiolite belt in the southern margin of centeral Iran microcontinent, comprise of mantle peridotites and crustal sequence. The serpentinized peridotites have cpx- bearing harzhburgite and lherzholite compositions which cross cut by diabase isolated dikes. The plutonic part of crustal sequence consist isotropic gabbro, diabase sheeted dike complex, intruded by wherlitic intrusion, quartz diorite, pegmatite gabbro and plagiogranite-tronjemite. The volcanic sequence consist of the intercalation of the chert and radiolarite, pelagic limestone have the Upper Cretaceous micro faunas at base of sequence and hyaloclasic braccia, hyaloclastite, sheet flow, tuff and pillow lave on top of the sequence. Study of chemical analysis indicating a supra-subduction origin and enrichments for REE, Rb, Ba and Th might be affecting of slab-derived fluids. It seem that Kahduiyeh tectonized Ophiolite display a consistent sequence of events during their formation and evolution, includes birth, youth and maturity stages which is a natural consequence of ophiolite formation in the Supra-subduction zones.
