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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: Shiribeshi Seamount is a Quaternary volcano in the back-arc region off the junction of the Northeast Japan and Kurile arcs as discussed by the authors, which shows a typical island arc calc-alkaline nature on the basis of petrographical characteristics.
Abstract: Shiribeshi Seamount is located to the east of the Okushiri Ridge, in the northeast Japan Sea Whole rock K-Ar age of olivine-augite andesite dredged from the Seamount was determined to be 09 ± 02 Ma (Tsuchiya et al, 1989), indicating that Shiribeshi Seamount is a Quaternary volcano in the back-arc region off the junction of the Northeast Japan and Kurile arcs Shiribeshi volcano is composed of basalt to rhyolite, which show a typical island arc calc-alkaline nature on the basis of petrographical characteristics of 95 samples dredged from four sites Abundances of incompatible elements including K, Rb, Sr, Nb, P, Ti, Y and Zr in 16 representative rocks are discussed, together with those in the Quaternary volcanic rocks from the NE Japan and Kurile arcs in terms of compositional variation across the arcs The estimated composition of the primary magma of Shiribeshi volcano is characterized by higher incompatible element contents and a higher Zr/Y ratio than primary magmas in the volcanic front side Based on HFS element concentrations the degree of partial melting for three primary magmas of Oshima-Oshima, Shiribeshi and Rishiri volcanoes in the northeast Japan Sea may decrease gradually with increasing distance from the volcanic front However, LIL element contents, especially K and Rb are lower in the primary magma of Rishiri volcano located far from the volcanic front than in the remaining two primary magmas, which would imply that LIL/HFS ratios (or degree of contribution of LIL elements originating from the subducted oceanic crust) become minimal at Rishiri volcano One basalt and three andesites from Shiribeshi volcano have the restricted range of low87Sr/86Sr ratios of 070297–070300, which indicates that the magma source for Shiribeshi volcano may be slightly more enriched in Sr isotopic compositions than theN-type MORB source
13 citations
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TL;DR: This article reported new Hf isotopic data for basaltic glasses from seamounts flanking the East Pacific Rise (EPR) between 5° and 15°N that have been previously analyzed for Sr-Nd-Pb isotopes as well as major and trace elements.
13 citations
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01 Jan 1986TL;DR: Investigation of the geochemistry of kimberlite is hampered by problems inherent in the intrusive styles characteristic of this volatile-rich magma; by the hybrid nature of the rocks formed from magmas which carry a high proportion of crystalline phases at their time of emplacement; and by the high probability of contamination of some facies by crustal materials and/or groundwater as mentioned in this paper.
Abstract: Investigation of the geochemistry of kimberlite is hampered by problems inherent in the intrusive styles characteristic of this volatile-rich magma; by the hybrid nature of the rocks formed from magmas which carry a high proportion of crystalline phases at their time of emplacement; and by the high probability of contamination of some facies by crustal materials and/or groundwater.
13 citations
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TL;DR: A compositionally varied swarm of mafic dykes in the Jetty Peninsula area was emplaced about 320 Ma ago (K-Ar age) as mentioned in this paper, and there are three major groups: Group 1 dykes range from transitional-alkaline dolerites to camptonites, Group 2 are trachydolerites, and Group 3 are diorite to quartz porphyries.
Abstract: A compositionally varied swarm of mafic dykes in the Jetty Peninsula area was emplaced about 320 Ma ago (K-Ar age). There are three major groups: Group 1 dykes range from transitional-alkaline dolerites to camptonites, Group 2 are trachydolerites, and Group 3 are diorite to quartz diorite porphyries. Group 1 dykes have very similar ratios of most incompatible elements and were derived from the same (or a very similar) enriched lithospheric mantle source region (∈ Nd −0.18 to −3.05) with high Nb and Ta (i.e., OIB, ocean island basalt, characteristics). However, the presence of several distinct subgroups with different incompatible element abundances implies significantly different degrees of melting. Group 2 trachy dolerites are much more fractionated ( mg 22–36), but were apparently derived from a similar, although somewhat more enriched (∈ Nd −2.26 to −4.63) source. Group 3 diorites are compositionally quite distinct and may have been derived by intracrustal melting. Enrichment of the mantle source(s) of Groups 1 and 2 dykes apparently occurred about the same time as high-grade metamorphism in the area, and may have been coeval with crust formation in nearby parts of Gondwana.
13 citations
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TL;DR: In this article, the authors analyzed zircon from four depths in IODP Site 735B; they come from the oxide gabbro and plagiogranite (depths c. 500, 860, 940m below sea floor).
Abstract: Felsic veins (plagiogranites) are distributed throughout the whole oceanic crust section and offer insight into late-magmatic/high temperature hydrothermal processes within the oceanic crust. Despite constituting only 0.5% of the oceanic crust section drilled in IODP Site 735B, they carry a significant budget of incompatible elements, which they redistribute within the crust. Such melts are saturated in accessory minerals, such as zircon, titanite and apatite, and often zircon is the only remaining phase that preserves magmatic composition and records processes of felsic melt formation and evolution. In this study, we analysed zircon from four depths in IODP Site 735B; they come from the oxide gabbro (depth approximately 250 m below sea floor) and plagiogranite (depths c. 500, 860, 940 m below sea floor). All zircons have similar eHf composition of c. 15 units indicating an isotopically homogenous source for the mafic magmas forming IODP Site 735B gabbro. Zircons from oxide gabbro are scarce and variable in composition consistent with their crystallization from melts formed by both fractionation of mafic magmas and hydrous remelting of gabbro cumulate. On the other hand, zircon from plagiogranite is abundant and each sample is characterized by compositional trends consistent with crystallization of zircon in an evolving melt. However, the trends are different between the plagiogranite at 500 m bsf and the deeper sections, which are interpreted as the record of plagiogranite formation by two processes: remelting of gabbro cumulate at 500 m bsf and fractionation at deeper sections. Zircon from both oxide gabbro and plagiogranite has δ18O from 3.5 to 6.0‰. Values of δ18O are best explained by redistribution of δ18O in a thermal gradient and not by remelting of hydrothermally altered crust. Tentatively, it is suggested that fractionation could be an older episode contemporaneous with gabbro crystallization and remelting could be a younger one, triggered by deformation and uplift of the crustal pile.
13 citations