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Incompatible element
About: Incompatible element is a research topic. Over the lifetime, 2420 publications have been published within this topic receiving 154052 citations.
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TL;DR: A self-consistent model for noble gases involves a gas-poor planet with trapping of CO2 and noble gases in the shallow mantle and high 3He/4He gases are viewed as products of ancient gas exsolution stored in low U environments, rather than products of primordial reservoirs.
Abstract: As a result of an energetic accretion, the Earth is a volatile-poor and strongly differentiated planet. The volatile elements can be accounted for by a late veneer (≈1% of total mass of the Earth). The incompatible elements are strongly concentrated into the exosphere (atmosphere, oceans, sediments, and crust) and upper mantle. Recent geochemical models invoke a large primordial undegassed reservoir with chondritic abundances of uranium and helium, which is clearly at odds with mass and energy balance calculations. The basic assumption behind these models is that excess “primordial”^3He is responsible for ^3He/^4He ratios higher than the average for midocean ridge basalts. The evidence however favors depletion of ^3He and excessive depletion of ^4He and, therefore, favors a refractory, residual (low U, Th) source Petrological processes such as melt-crystal and melt-gas separation fractionate helium from U and Th and, with time, generate inhomogeneities in the ^3He/^4He ratio. A self-consistent model for noble gases involves a gas-poor planet with trapping of CO_2 and noble gases in the shallow mantle. Such trapped gases are released by later tectonic and magmatic processes. Most of the mantle was depleted and degassed during the accretion process. High ^3He/^4He gases are viewed as products of ancient gas exsolution stored in low U environments, rather than products of primordial reservoirs.
93 citations
TL;DR: The relative abundances of immobile elements (such as calcium, aluminium, titanium, zirconium and rare-earth elements) in the ultramafik lavas known as komatiites have provided important information about the composition of the early Earth's mantle as discussed by the authors.
Abstract: THE relative abundances of immobile elements (such as calcium, aluminium, titanium, zirconium and the rare-earth elements) in the Archaean ultramafik lavas known as komatiites have provided important information about the composition of the early Earth's mantle, but to establish the origin and tectonic setting of these lavas one also needs the abundances of mobile elements, such as the alkali metals, alkaline-earth elements, and uranium and lead. Up to now, it has not been possible to use these elements in constraining komatiite petrogenesis, because of the pervasive effects of alteration in these ancient lavas; recently, however, some remarkably fresh, 2.7-Gyr-old komatiites have been discovered, which contain unaltered olivine crystals and small glass inclusions1. We report ion micoprobe data for 25 trace elements from these glass inclusions, and show that the ratios of mobile to immobile incompatible elements are similar to those found in modern intraplate basalts, and distinct from modern mid-ocean-ridge and convergent-margin basalts. We infer that these Archaean magmas formed from sources similar to (or slightly depleted relative to) those of modern intraplate basalts, supporting the suggestion2,3 that komatiites are ancient analogues of modern plume-related magmas.
92 citations
TL;DR: In this paper, the authors presented a geochemical and isotope data for the Harrat Al-Madinah volcanic field, in the north western part of the Arabian plate, aiming to understand their origin and the composition of their mantle source.
92 citations
TL;DR: The 2.7 Ga Ramagiri-Hungund composite greenstone belt (RHST) is one of a series of volcanic dominated supracrustal belts in the eastern Dharwar craton.
92 citations
TL;DR: In this article, a model of mixing is proposed between relatively enriched and depleted end-members, suggesting that the Black Cone magma represents one of the mixing endmembers, at least during the early stages of volcanism, which could have significant implications for volcanic hazard assessment in the region around Yucca Mountain and the proposed nuclear waste repository.
92 citations