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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 this article, major and trace element and isotope data for variably metasomatized bulk-rock peridotites from spinel lherzolite and harzburgite xenoliths from the Kilbourne Hole volcanic maar was presented.
Abstract: Significant differences between bulk-rock lithophile trace element budgets and the sum of the contributions from the constituent minerals are common, if not ubiquitous, in peridotite xenoliths. Notwithstanding the possible contributions from fluid inclusions and grain-boundary glass and micro-phases, it is often difficult to reconcile the bulk-rock incompatible element budgets with those of the silicate phases. In the absence of modal metasomatism this discrepancy is often attributed to the ‘catch-all’yet often vague process of cryptic metasomatism.This study presents comprehensive petrological descriptions, major and trace element and Sr^Nd isotope data for variably metasomatized bulk-rock peridotites, host basalt, and constituent peridotite mineral phases from spinel lherzolite and harzburgite xenoliths from the Kilbourne Hole volcanic maar, New Mexico, USA. Similar measurements were also made on hand-picked interstitial glass from one of the most highly metasomatized samples in an attempt to unravel the sources, effects, and relative timings of multiple metasomatic events. Reaction textures around clinopyroxene grains are evident in the most metasomatized samples. These are accompanied by films of high-SiO2 interstitial glass, which is not in equilibrium with the primary silicate minerals. Trails of glassy melt inclusions terminate in these films against which the margins of the primary minerals appear partially resorbed. Furthermore, different styles of high field strength element fractionation [e.g. (Nb/Ta)N vs (Zr/Hf)N] are evident in the bulk-rocks and the clinopyroxenes that they host. In all of the Kilbourne Hole peridotites analysed, hand-picked, optically clean clinopyroxenes preserve a more unradiogenic Sr isotope signature than the corresponding bulk-rock. Hand-picked interstitial glass from KH03-16 reveals the most radiogenic Sr/Sr of any component recovered from these xenoliths (Sr/Sr1⁄4 0·708043 0·00009; [Sr]1⁄4 81ppm). Similarly, the Nd/Nd of the glass is amongst the most evolved of the peridotite components (Nd/Nd1⁄4 0·512893 0·000012; [Nd]1⁄4 10 ppm). However, the host basalt (Sr/Sr1⁄4 0·703953 0·00012; Nd/Nd1⁄4 0·512873 0·000013), similar in composition to that of the nearby, contemporaneous, Potrillo Volcanic Field basalts, contains nearly an order of magnitude more Sr and more than three times more Nd ([Sr]1⁄4 655 ppm; [Nd]1⁄4 34 ppm) than the interstitial glass. Despite the high Sr and Nd contents of the host basalt the evidence for basalt infiltration is scant, although the effects of melt^rock interaction, both in antiquity and more recently, are preserved in several xenoliths. Mixing between clinopyroxene and the host basalt cannot account for the full range of bulk-rock Sr^Nd isotope ratios; nearly half of the xenoliths require an additional component that could involve varying amounts of interstitial glass. In detail the behaviour of Sr and Nd isotopes has been decoupled,
48 citations
TL;DR: In this paper, the authors show that the role of sulfide during mantle melting may be insignificant with regards to controlling the concentration of moderately chalcophile elements like Cu, and confirm that the previously estimated Cu content for PUM of 20 pm is correct.
48 citations
TL;DR: In this paper, the authors used radiogenic isotopes in oceanic basalts to provide tracers of long-lived heterogeneities in the Earth9s mantle, and found that high 3 He / 4 He ratios are indicative of relatively undegassed mantle reservoirs (i.e. mantle with high timeintegrated 3 He/(Th + U) ratios).
Abstract: Radiogenic isotopes in oceanic basalts are extremely useful as tracers of long-lived heterogeneities in the Earth9s mantle. Helium isotopes provide unique information in that high 3 He / 4 He ratios are indicative of relatively undegassed mantle reservoirs (i.e. mantle with high time-integrated 3 He/(Th + U) ratios). An alternative hypothesis is that high 3 He / 4 He ratios may have been produced by ancient melting events, if the solid/melt partition coefficient (K d ) for He is greater than that for Th and U (i.e. yielding relatively high He/(Th + U) in the residue of melting). However, the distribution of helium within basaltic phenocrysts, and olivine/glass helium partitioning within mid-ocean ridge basalts, suggest that helium behaves as an incompatible element during melting (K d (olivine/glass) 3 He / 4 He ratios are derived from undegassed mantle reservoirs. Isotopic measurements of He, Sr, and Pb in Hawaiian volcanoes lavas demonstrate that the mantle sources have changed on extremely short timescales, between 100 and 10 000 years before present. The preferred explanation for these variations is that they represent heterogeneities within the Hawaiian mantle plume, combined with late stage melting in the lithosphere for post shield alkali basalts. Helium isotopic data from Kilauea, Hualalai and Mauna Loa suggest that the plume is presently located beneath Kilauea (and Loihi seamount), and constrain the melting zone of the Hawaiian plume to be less than 40 km in radius.
48 citations
TL;DR: Two groups of granitoids associated with gold mineralization in the Appalachian orogen of southwestern New Brunswick are recognized: a Late Silurian to Early Devonian (423-396) granodioritic to monzogranitic series (GMS), and a Late Devonian granitic series(GS) as discussed by the authors.
48 citations
TL;DR: In this article, a comparison of the geochemical composition of Turkish ignimbrites associated with borates with those that do not ('barren' ignimbrite), exhibit a number of features that might prove useful in the exploration for borate in similar volcanic domains.
48 citations