Crustal Contamination and Hybridization of an Embryonic Oceanic Crust during the Red Sea Rifting (Tihama Asir Igneous Complex, Saudi Arabia)

The Red Sea rift system represents a key case study of the transition from a continental to an oceanic rift. The Red Sea rifting initiated in Late Oligocene to Early Miocene (24-23 Ma) and was accompanied by extensive magmatism throughout the rifted basin, from Afar and Yemen to northern Egypt. Here, we present a petrological and geochemical study of two gabbro bodies and associated basalts from the Tihama Asir igneous complex, which formed at 24-20 Ma within the rifted Arabian-Nubian Shield (ANS). The Tihama Asir is therefore an ideal location to study the initial phase of syn-rift magmatism and its influence on the geodynamic evolution of the Red Sea rift system. The most primitive olivine gabbros present modal, bulk and mineral compositions consistent with formation from Mid-Ocean Ridge Basalt (MORB)-type parental melts, whereas the evolved olivine-free gabbros and oxide-bearing gabbros show saturation of phlogopite and a crystal line of descent diverging from fractional crystallization trends. In detail, whole-rock and mineral compositions in the most evolved lithologies show high Light over Middle Rare Earth Elements (LREE/MREE) ratios (La-N/Sm-N = 0.89-1.31) and selective enrichments in Sr, K and highly incompatible elements (Rb, Ba, U, Th). We relate these geochemical characteristics to a process of progressive assimilation of host continental crust during the emplacement of the gabbroic plutons. Interestingly, high LREE/MREE ratios (La-N/Sm-N = 1.45-4.58) and high Rb, Ba, Th and U contents also characterize the basaltic dike swarms associated to the gabbros. Incompatible trace element compositions of these basalts approach those of the melts that formed the most hybridized gabbros. Therefore, we propose that the dike swarms represent melts partially contaminated by assimilation of continental crust material, extracted from the underlying gabbroic crystal mush. Our results suggest that early syn-rift magmatism led to the partial replacement of the thinned continental crust by MORB-type gabbroic bodies, in turn suggesting that oceanic magmatism started prior to continental break-up. Extensive syn-rift magmatism is consistent with the interpretation of the southern Red Sea rift system as a volcanic rifted margin. One possible implication of this study is that extensive but diffuse syn-rift magmatism possibly hampered continental break-up, leading to a protracted rifting stage

TRANSITION FROM A CONTINENTAL TO AN OCEANIC RIFT IN THE NORTHERN RED SEA

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The politics of knowledge, epistemological occlusion and Islamic management and organization knowledge

This article argues that Islamic management and organization knowledge (MOK) is relatively under- and mis-represented in the literature. This conclusion is reached following a detailed literature survey and analysis which also examines some of the core representational practices used to account for Islam in the literature: the persistence of essentialism and orientalism; the disposition to refract instances of Islamic MOK through Northern lenses; and the tendency for some Southern scholars and institutions to become intellectually captive to the North’s knowledge system. We discuss this in the context of a politics of knowledge that bears on knowledge production and dissemination processes in MOK. This reveals continued intellectual and cultural imperialism, sustained Western hegemony, and the exclusionary practices of the North’s associated discourses and institutional frameworks that valorise and elevate Northern epistemology, theory and method, but devalues and marginalize alternatives. We argue that any neglect of Islam is unwarranted given (a) its global significance on a range of dimensions, (b) the particularities of its relations to the North—characterized by orientalism and Islamophobia and (c) the presence of a distinctive Islamic worldview, epistemology and ethics that informs practical action, including management and organization. This entails that an Islamic MOK offers prospects of an alternative or complement to the North’s orthodox perspective and is deserving of a proper voice in the literature. We conclude by offering practical suggestions for change