THE ORIGIN OF THE KAHNUJ OPHIOLITIC COMPLEX, SE OF IRAN: CONSTRAINTS FROM WHOLE ROCK AND MINERAL CHEMISTRY OF THE BANDE-ZEYARAT GABBROIC COMPLEX

摘要: The Upper Jurassic-Lower Cretaceous Kahnuj ophiolite complex, a part of Jazmurian ophiolitic belt, is situated in the southeastern Iran and represents remnant Mesozoic Neotethyan Ocean. oceanic lithospheric section comprises from bottom to top: plutonic unit (Bande-Zeyarat Complex); diabase sheeted dyke unit; volcanic (Dare-Anar Complex). Although it extensively faulted fractured, internal relationships have been preserved. Bande-Zeyarat gabbroic complex consists layered cumulates isotropic gabbros. cumulate gabbro shows adcumulate, mesocumulate orthocumulate textures represented exclusively by olivine gabbro, melagabbro, leucogabbro, anorthosite, with minor troctolite, gabbronorite, pegmatoid tectonic rafts dunite. characterized well-developed magmatic layering, defined variation mode /or size plagioclase mafic minerals, foliation which marked preferred flattening all mineral phases. These two structures for most parts are sub-parallel each other. Rhythmic layering also present. hypidiomorphic granular uralitized pyroxene hornblende ilmenite-rich diorite trondhjemite. They fractionated gabbros, more albite rich, clinopyroxene iron rich. strong positive Eu anomalies, attributable high modal abundances plagioclase, whereas predominant over does not any anomalies. gabbros crystallized influxes slightly different less magnesiferous parental melts. related crystal fractionation represent late differentiation products formed as rate magma influx slowed finally ceased. Mineral assemblages, chemistry (i.e., Fo67.8-78.54, low Mg# < 84.16 Si relative tetrahedral Al clinopyroxenes), crystallization order (olivine-plagioclase-clinopyroxene) whole rock suggest that has produced moderate pressure tholeiitic basaltic similar MORB. data indicate may an basin developed between Lut block Central Bajgan-Dur-Kan microcontinents.