Topic
Incompatible element
About: Incompatible element is a research topic. Over the lifetime, 2420 publications have been published within this topic receiving 154052 citations.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this article, the authors studied inclusions in plagioclase and olivine phenocrysts in these basalt basalt lavas and found that the less incompatible element enriched type II lavas are more enriched in Cu than type I, an observation that is relevant to the origin of metals characteristic of these particular basalt-hosted seafloor hydrothermal systems.
13 citations
••
TL;DR: The dike-vein complex of the Moncha Tundra Massif comprises dolerites, gabbro-pegmatites, and aplites as discussed by the authors.
Abstract: The dike-vein complex of the Moncha Tundra Massif comprises dolerites, gabbro-pegmatites, and aplites. The dolerite dikes are classified into three groups: high-Ti ferrodolerites, ferrodolerites, low-Ti and low-Fe gabbro-dolerites. The U-Pb age of the ferrodolerites is 2505 ± 8 Ma, and the amphibole-plagioclase metagabbroids hosting a ferrodolerite dike are dated at 2516 ± 12 Ma. Data on the U-Pb isotopic system of zircon from the gabbro-pegmatites and titanite from the aplites indicate that the late magmatic evolution of the Moncha Tundra Massif proceeded at 2445 ± 1.7 Ma, and the youngest magmatic events in the massif related to the Svecofennian orogeny occurred at 1900 ± 9 Ma. The data obtained on the Sm-Nd and Rb-Sr isotopic systems and the distribution of trace elements and REE in rocks of the dike-vein complex of the massifs provide insight into the composition of the sources from which the parental magmas were derived. The high-Ti ferrodolerites were melted out of a deep-sitting plume source that contained an asthenospheric component. The ferrodolerites were derived from a mantle MORB-type source that contained a crustal component. The parental melts of the gabbro-dolerites were melted out of the lithospheric mantle depleted in incompatible elements after Archean crust-forming processes above an ascending mantle plume, with the participation of a crustal component. The gabbro-dolerites and the rocks of the layered complex of the Moncha Tundra Massif exhibit similar geochemical characteristics, which suggest that their parental melts could be derived from similar sources but with more clearly pronounced crustal contamination of the parental melts of the rocks of the massif itself. The geochemical traits of the gabbro-pegmatites are thought to be explained not only by the enrichment of the residual magmas in trace elements and a contribution of a crustal component but also by the uneven effect of sublithospheric mantle sources. The aplites were derived from a sialic crustal source.
13 citations
••
TL;DR: In this paper, the authors show that an ocean-island basalts (OIB) component with the characteristics of the mantle endmember HIMU8 (notably, high U/Pb ratio) is present in arc magmas of the Mariana Island region (Philippine Sea).
Abstract: THE strontium, neodymium and lead isotopic compositions of most island-arc magmas seem to require a component in the source region with the characteristics of ocean-island basalts (OIB)1–5. In contrast, however, the trace-element compositions of arc magmas and OIB do not match: OIB sources are highly enriched in incompatible elements, whereas island-arc basalts are depleted in high-field-strength and light rare-earth elements. Peridotite that has undergone an episode of melting, and hence depletion of incompatible elements, is an appropriate source for island-arc basalts6,7. I have previously proposed that an OIB component with the characteristics of the mantle endmember HIMU8 (notably, high U/Pb ratio) is present in arc magmas of the Mariana Island region (Philippine Sea). Here I show, using isotopic comparisons of Philippine Sea arc and basin magmas, including the highly magnesian lavas known as boninites, that this HIMU component is refractory and is selectively incorporated into the depleted mantle lithosphere during extraction of mid-ocean-ridge basalt and back-arc-basin basalt. This process creates the mixture of depleted and OIB-source mantle required for island-arc basalt.
13 citations
••
TL;DR: The Serra Geral Fm. as mentioned in this paper is made up of initial flows of acidic composition which were deposited over the sandstones of the Botucatu Fm., and were covered by basalt flows which crop out north of the Paranapanema river.
Abstract: The Serra Geral Fm. in the Piraju-Ourinhos region (SW of the State of Sao Paulo) is made up of initial flows of acidic composition which were deposited over the sandstones of the Botucatu Fm., and were covered by basalt flows which crop out north of the Paranapanema river. Geochemical analyses of a suite of extrusive and intrusive basic rocks reveal significant variations that can be used as tools for stratigraphic correlation. All the rocks from flows and a significant proportion of the intrusive rocks show affinity with the Pitanga basalt type. A set of dike rocks, however, shows lower Ti/Y ratios and weakly fractionated primitive mantle-normalized incompatible element patterns, and are interpreted as conduits of younger basalt flows, now eroded, and equivalent to the Paranapanema type. Samples from one sill, on the other hand, are characterized by more fractionated incompatible element patterns and high Sr contents, indicative of the presence of Urubicitype magmas, previously unknown in this region.
13 citations
•
01 Jan 1988
TL;DR: The dykes from the Igaliko Nepheline syenite complex belong to at least three individual swarms (i) a Mid Gardar swarm in the Ostfjordsdal valley, (ii) a Late-Gardar, Si-oversaturated swarm associated with the Younger Giant Dykes of Tugtutoq and (iii) a Si-understandably, the main oversaturated and undersaturated suites can be separated on their Zr/Nb ratios (≈6.4 and 3.9 respectively) as mentioned in this paper.
Abstract: The dykes from the Igaliko Nepheline Syenite complex belong to at least 3 individual swarms (i) a Mid-Gardar swarm in the Ostfjordsdal valley, (ii) a Late-Gardar, Si-oversaturated swarm associated with the Younger Giant Dykes of Tugtutoq and (iii) a Si-undersaturated swarm intimately associated with the Late Gardar Igaliko Nepheline Syenite Central Complexes. In addition Early Gardar activity is recorded by the presence of some ultramafic lamprophyres which predate the Motzfeldt centre, sparse trachytes which are truncated by intrusions within the Motzfeldt centre and a possible BD(_0) dolerite which is also cut by the Motzfeldt centre. Most dykes however are bracketed between the Early and Late Igdlerfigssalik syenite intrusions. The main oversaturated and undersaturated suites can be separated on their Zr/Nb ratios (≈6.4 and 3.9 respectively). In addition, the undersaturated basic rocks have smooth chondrite normalised incompatible element spidergrams whereas the oversaturated basic rocks are characterised by negative Nb and positive P anomalies. Evolution of both suites can be modelled in terms of fractional crystallisation of feldspar, clinopyroxene, olivine, apatite and opaques from basaltic parents to either phonolitic or rhyolitic minimum compositions. In each instance these evolved composi tions are extremely rich in incompatible trace elements (REE, Nb, Zr, Rb). In some cases a high CO(_2) content in the undersaturated rocks may lead to the formation (by liquid immiscibility) of late stage carbonatite magmas. High CO(_2) also produces high ƒo(_2) in these magmas and it is argued that in some cases this can suppress the development of negative Eu anomalies on feldspar fractionation. The undersaturated swarm may have evolved from lamprophyric parental magmas, eg. camptonites, which are relatively abundant basic dykes. Ultramafic lamprophyres, often early, may have formed as extremely small degree partial melts at the onset of Gardar rifting. In the Late Gardar, magma genesis is related to the different extensional tectonic regimes which were operative at that time. Mineralogical evolution follows paths similar to several other Gardar suites and records a higher ƒo(_2) in the undersaturated rocks. Zr becomes concentrated in interstitial residual liquids in benmoreites and substitutes into amphibole as the newly proposed end-member zirconian-arfvedsonite.
13 citations