Abstract
Ophiolite-hosted diamond from peridotites and podiform chromitites significantly differs from those of kimberlitic diamond and ultra-high pressure (UHP) metamorphic diamond in terms of occurrence, mineral inclusion, as well as carbon and nitrogen isotopic composition. In this review, we briefly summarize the global distribution of twenty-five diamond-bearing ophiolites in different suture zones and outline the bulk-rock compositions, mineral and particular Re-Os isotopic systematics of these ophiolitic chromitites and host peridotites. These data indicate that the subcontinental lithospheric mantle is likely involved in the formation of podiform chromitite. We also provide an overview of the UHP textures and unusual mineral assemblages, including diamonds, other UHP minerals (e.g., moissanite, coesite) and crustal minerals, which robustly offer evidence of crustal recycling in the deep mantle along the suprasubduction zone (SSZ) and then being transported to shallow mantle depths by asthenospheric mantle upwelling in mid-ocean-ridge and SSZ settings. A systematic comparison between four main genetic models provides insights into our understanding of the origin of ophiolite-hosted diamond and the formation of podiform chromitite. Diamond-bearing peridotites and chromitites in ophiolites are important objects to discover new minerals from the deep earth and provide clues on the chemical composition and the physical condition of the deep mantle.
Highlights
According to the differences in occurrence and genesis, natural diamonds are divided into various types, including diamonds occurring in kimberlite, lamproite, ophiolite, alkaline mafic rock, crust-derived ultrahigh-pressure (UHP) metamorphic rock, meteoroliterelated and alluvial rocks [1,2,3,4,5]
This paper summarizes the geological characteristics of diamond-bearing ophiolites and discusses the four genetic models for the diamond-bearing and associated unusual minerals-bearing ophiolites, providing a basis for discussing the formation of ophiolitic chromitite and the dynamic process of crust–mantle material recycling
Twenty-five diamond-bearing ophiolites have been discovered across the globe, and they are mainly distributed along the Tethyan Orogenic Belt, the Ural-Central Asian Orogenic Belt, the Hidaka metamorphic belt, the Klamath–Acatlán Orogenic Belt in North America and the Andean Orogenic Belt in South America (Figure 1a)
Summary
According to the differences in occurrence and genesis, natural diamonds are divided into various types, including diamonds occurring in kimberlite, lamproite, ophiolite, alkaline mafic rock, crust-derived ultrahigh-pressure (UHP) metamorphic rock, meteoroliterelated and alluvial rocks [1,2,3,4,5]. Jingsui Yang and his group continued this research, and diamonds were discovered in the ophiolites of Luobusa, Purang, Dongbo, Dangqiong and Dingqing in Tibet, Sartohay in Xinjiang, Hegenshan in Inner Mongolia, Myitkyina and Kalemyo in Myanmar, PozantiKarsanti in Turkey, Mirdita in Albania and Horoman in Japan [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33] As these diamonds were extracted by heavy mineral separation in the early stage, their natural origin was initially doubted [7,34]. This paper summarizes the geological characteristics of diamond-bearing ophiolites and discusses the four genetic models for the diamond-bearing and associated unusual minerals-bearing ophiolites, providing a basis for discussing the formation of ophiolitic chromitite and the dynamic process of crust–mantle material recycling
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