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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: In the early Proterozoic Oonagalabi basement gneiss complex, Harts Range, Central Australia as discussed by the authors, basaltic melts which were parental to the two mafic suites were not comagmatic and the rocks cannot be related simply by fractionation of realistic assemblages of low-pressure fractionating phases.
Abstract: Extremely fractionated basaltic to ferrobasaltic amphibolites and granulites comprise two spatially associated mafic tholeiitic suites (?deformed sills) within the Early Proterozoic Oonagalabi basement gneiss complex, Harts Range, Central Australia. The metatholeiites are characterised by high to very high FeO, TiO2 and P2O5 contents, and variable depletion in CaO and Al2O3. Despite similar Zr/Nb ratios, the rocks from the two suites show different degrees of enrichment in LREE and other “immobile” incompatible elements. The basaltic melts which were parental to the two mafic suites were not comagmatic and the rocks cannot be related simply by fractionation of realistic assemblages of low-pressure fractionating phases. The data suggest that primary basaltic liquids for the two suites were derived by different degrees of partial melting from essentially similar undepleted mantle source regions. Clinopyroxene in the residual mantle assemblage controlled the composition of the segregating melt at lower degrees of melting. The ferrobasaltic compositions imply long residence times for the basaltic magmas in shallow-level differentiating tholeiitic sills and/or magma chambers in a mature propagating rift environment. High-grade (granulite facies) metamorphism, and subsequent restricted metasomatic reequilibration of the mafic rocks with interlayered migmatitic and quartzofeldspathic gneisses, have affected only abundances of certain highly-smobile elements (e.g. K2O and Rb), resulting in the partial disruption of inter-element correlations. However, the geochemical data do not indicate any large-scale depletion of large ion lithophile elements (LILE) in the Oonagalabi gneiss complex.
13 citations
TL;DR: In this paper, an ultramafic lamprophyre dyke was found to have a minimum age of 1928±54 Ma as a late event of the Transamazonian Orogeny.
13 citations
TL;DR: In this article, the authors used the Re-Os system to fingerprint juvenile lithospheric mantle enrichment events and have important implications for the generation of ocean island-like Nd and Hf isotopic signatures in kimberlites and carbonatites.
13 citations
TL;DR: In this paper, the authors show that the low-K tholeiitic metavolcanic rocks were derived by a relatively lower degree of melting from a more depleted mantle source than the boninites.
13 citations
TL;DR: In the literature, the term "incompatible" denotes a preference of the element for a melt over mantle minerals as mentioned in this paper, which is the case for most of the elements in a basalt.
Abstract: The mantle can be sampled directly only very rarely. Geochemists have thus come to rely heavily on mantle-derived magmas to study the composition and evolution of the mantle. Only those compositional features that are unaffected by magmatic processes are useful as tracers of mantle processes. These include radiogenic isotope ratios such as those of He, Sr, Hf, and Os, stable isotope ratios, and ratios of highly incompatible elements or elements of similar incompatibility, such as Ba/Nb or Pb/Ce. The term “incompatible” denotes a preference of the element for a melt over mantle minerals. Highly incompatible elements will partition entirely into the melt under most circumstances, so that the ratio of two such elements in a basalt will be virtually identical to that ratio in its source. This is also true to a lesser degree of ratios such as La/Sm and Zr/Nb, as Zr and Sm are not highly incompatible elements.
12 citations