Entries by Gelu Costin

Nature: Scientific Reports: A 5‑km‑thick reservoir with > 380,000 km3 of magma within the ancient Earth’s crust

Rais Latypov, Sofya Chistyakova, Richard A. Hornsey, Gelu Costin & Mauritz van der Merwe   Abstract Several recent studies have argued that large, long-lived and molten magma chambers may not occur in the shallow Earth’s crust. Here we present, however, field-based observations from the Bushveld Complex that provide evidence to the contrary. In the eastern […]

Lithos: Correlations between olivine composition and groundmass mineralogy in Sierra Leone kimberlites provide constraints on craton-specific melt-lithosphere interactions

Anton Viljoen, Geoffrey H. Howarth, Andrea Giuliani, Angus Fitzpayne, Gelu Costin   Abstract Sierra Leone contains two Jurassic-aged diamondiferous kimberlite clusters, namely Koidu and Tongo-Tonguma (hereafter referred to as Tongo), consisting of eruptive pipes and NE-SW trending dikes. In this study, a combination of detailed petrography, and phlogopite, spinel, and olivine compositions in hypabyssal samples […]

Precambrian Research: Origin of the J-M Reef and lower banded series, Stillwater Complex, Montana, USA

Christopher Jenkins, James E. Mungall, Michael L. Zientek, Gelu Costin, and Zhuo-Sen Yao The origin and parental magma for layered cumulates in the Lower Banded series (LBS) and the J-M Reef Pd-Pt deposit of the Stillwater Complex remains poorly constrained. We present whole-rock lithogeochemistry and mineral chemistry from LBS rocks collected from drill holes and […]

Earth-Science Reviews: Cognate versus xenocrystic olivines in kimberlites – A review

Authors: Andy Moore, Gelu Costin, Alexander Proyer Abstract Models for a xenocryst origin for kimberlite olivines emphasise the similarity between their core compositions and those in mantle peridotites. While this permits a xenocryst origin, it does not provide proof, as magmas generated in equilibrium with mantle olivines could, in principle, crystallize initial olivines matching those in the source […]

Science Advances: Crustal thickening and endogenic oxidation of magmatic sulfur

Ming Tang, Cin-Ty Lee, Wei-Qiang Ji, Rui Wang, Gelu Costin Abstract Porphyry ore deposits, Earth’s most important resources of copper, molybdenum, and rhenium, are strongly associated with felsic magmas showing signs of high-pressure differentiation and are usually found in places with thickened crust (>45 kilometers). This pattern is well-known, but unexplained, and remains an outstanding […]

Nature Communications: Molecular hydrogen in minerals as a clue to interpret ∂D variations in the mantle

B. N. Moine, N. Bolfan-Casanova, I. B. Radu, D. A. Ionov, G. Costin, A. V. Korsakov, A. V. Golovin, O. B. Oleinikov, E. Deloule & J. Y. Cottin Abstract Trace amounts of water dissolved in minerals affect density, viscosity and melting behaviour of the Earth’s mantle and play an important role in global tectonics, magmatism […]

Mineralium Deposita: Hybrid norite and the fate of argillaceous to anhydritic shales assimilated by Bushveld melts

Yudovskaya, M. A., Costin, G., Sluzhenikin, S. F., Kinnaird, J. A., Ueckermann, H., & Abramova, V. D.   Mafic sills of the Marginal Zone are widespread within the footwall of the Bushveld Complex with some of them being enclosed in later Bushveld intrusions. In the central sector of the northern limb of the Bushveld Complex […]

J Petrol: Non-sequential injection of PGE-rich ultramafic sills in the Platreef Unit at Akanani, Northern Limb of the Bushveld Complex: Evidence from Sr and Nd isotopic systematics

Roger N Scoon, Gelu Costin, Andrew Mitchell, Bertrand Moine Abstract The Platreef Unit is a deceptively complex sequence of layered cumulates located in the northern limb of the 2.055 Ga-old Bushveld Complex. The unit includes the Platreef, a thick, richly mineralized stratabound PGE orebody which differs markedly from the comparatively thin, predominantly stratiform Merensky Reef found in the […]

Scientific Reports: Monomineralic anorthosites in layered intrusions are indicators of the magma chamber replenishment by plagioclase-only-saturated melts

Rais Latypov, Sofya Chistyakova, Gelu Costin, Olivier Namur, Steve Barnes & Willem Kruger Abstract The formation of some Earth’s monomineralic igneous rocks appears to be prohibited by constraints imposed by liquidus phase-equilibria on the evolution of mantle-derived magmas. Yet, these rocks exist as stratiform layers in many mafic-ultramafic intrusions. One conspicuous example is monomineralic anorthosites […]