Coupled evolution of back-arc and island arc-like mafic crust in the late-Neoproterozoic Agardagh Tes-Chem ophiolite, Central Asia: evidence from trace element and Sr-Nd-Pb isotope data

AbstractSub-silicic to silicic pitchstones are widespread throughout the British Tertiary Igneous Province (BTIP), with examples being found at all the major igneous centres. Both highly porphyritic and almost completely aphyric varieties occur, and take the form of sills, dykes and lava flows. Here we present previously unreported mineral chemistry data on phenocryst and microcrystallite populations from a number of pitchstones from throughout the BTIP. Phenocryst assemblages are completely anhydrous, comprising mixtures of plagioclase, sanidine, fayalite, orthopyroxene, pigeonite, ferroaugite, ferrohedenbergite and quartz. Microcrystallite assemblages are also diverse, consisting of sanidine, ferrohedenbergite, fayalite and, occasionally, almost pure end-member ferrosilite, as well as hydrous phases such as ferrohornblende and biotite. Textural and mineral chemistry observations support interpretations derived from whole-rock and residual glass major element analyses, together with whole-rock trace element and the available Sr-Nd-Pb isotope data, that the Tertiary pitchstones of Scotland are either the products of intimate mixing between a range of basaltic magmas with hydrous crustal melts, or were formed by the crustal contamination of basaltic magmas.

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U-series, SrNdPb isotope and trace-element systematics across an active island arc-continent collision zone: Implications for element transfer at the slab-wedge interface

Geochimica et Cosmochimica Acta ◽

10.1016/s0016-7037(97)84621-2 ◽

1997 ◽

Vol 61 (5) ◽

pp. 1057-1072 ◽

Cited By ~ 80

Author(s):

J.A Hoogewerff ◽

M.J Van Bergen ◽

P.Z Vroon ◽

J Hertogen ◽

R Wordel ◽

...

Keyword(s):

Trace Element ◽

Island Arc ◽

Pb Isotope ◽

Collision Zone ◽

Element Transfer

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Discovery of Ancient Volcanoes in the Okhotsk Sea (Russia): New Constraints on the Opening History of the Kurile Back Arc Basin

Geosciences ◽

10.3390/geosciences10110442 ◽

2020 ◽

Vol 10 (11) ◽

pp. 442

Author(s):

Reinhard Werner ◽

Boris Baranov ◽

Kaj Hoernle ◽

Paul van den Bogaard ◽

Folkmar Hauff ◽

...

Keyword(s):

Trace Element ◽

Island Arc ◽

Kurile Island ◽

Geochemical Data ◽

Magma Source ◽

Published Data ◽

Kurile Island Arc ◽

History Of ◽

Spreading Rates ◽

Back Arc

Here we present the first radiometric age and geochemical (major and trace element and isotope) data for samples from the Hydrographer Ridge, a back arc volcano of the Kurile Island Arc, and a newly discovered chain of volcanoes (“Sonne Volcanoes”) on the northwestern continental slope of the Kurile Basin on the opposite side of the arc. The 40Ar/39Ar age and geochemical data show that Hydrographer Ridge (3.2–3.3 Ma) and the “Sonne Volcanoes” (25.3–25.9 Ma) have very similar trace element and isotope characteristics to those of the Kurile Island Arc, indicating derivation from a common magma source. We conclude that the age of the “Sonne Volcanoes” marks the time of opening of the Kurile Basin, implying slow back arc spreading rates of 1.3–1.8 cm/y. Combined with published data from the Kurile fore arc, our data suggest that the processes of subduction, Kurile Basin opening and frontal arc extension occurred synchronously and that extension in the rear part and in the frontal part of the Kurile Island Arc must have been triggered by the same mechanism.

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Melting of the mantle past and present: isotope and trace element evidence

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1978.0033 ◽

1978 ◽

Vol 288 (1355) ◽

pp. 547-559 ◽

Cited By ~ 71

Keyword(s):

Trace Elements ◽

Trace Element ◽

Internal Heat ◽

Oceanic Lithosphere ◽

Pb Isotope ◽

Transfer Event ◽

Isotope Data ◽

Source Regions ◽

Depleted Mantle ◽

Ocean Ridge

Estimates are made of the abundances of some lithophile trace elements, particularly heat-producing elements, in the bulk Earth. The applicability of abundance estimates based on extra-terrestrial analogues, and terrestrial heat flow data are discussed. Sr, Nd and Pb isotope data are briefly reviewed and used to identify basalt source regions in the mantle which have been depleted or enriched in these and other lithophile trace elements. An assessment is made of the role of silicate liquid transfer in the production of depleted mantle. The timing of the transfer event(s) can be constrained using Rb-Sr, Sm-Nd and U-Pb isotope data and cover the period of Earth history during which granitic crust has been stabilized. Calculations of the heat production in the source regions of mid-ocean ridge and other basalts suggest that the convective processes involved in the generation of oceanic lithosphere are driven mainly by heating from beneath, as the internal heat generation is comparatively small. Trace element data from Archaean to Recent volcanics are used to estimate maximum limits on the amount of mantle melting which has occurred in the last 3.5 Ga.

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Geochemistry, geochronology, and geodynamic setting of Ni–Cu ± PGE mineral prospects hosted by mafic and ultramafic intrusions in the Portneuf–Mauricie Domain, Grenville Province, QuebecGéologie Québec Contribution 8439-2008-2009-5. Geological Survey of Canada Contribution 20080511.

Canadian Journal of Earth Sciences ◽

10.1139/e09-022 ◽

2009 ◽

Vol 46 (5) ◽

pp. 331-353 ◽

Cited By ~ 15

Author(s):

A.-A. Sappin ◽

M. Constantin ◽

T. Clark ◽

O. van Breemen

Keyword(s):

Trace Element ◽

Crustal Contamination ◽

Island Arc ◽

Geodynamic Setting ◽

Grenville Province ◽

Magmatic Arc ◽

Andean Type ◽

Trace Element Signature ◽

Arc Setting ◽

Back Arc

The Portneuf–Mauricie Domain in the Grenville Province consists of the Montauban group rocks (1.45 Ga), intruded by the La Bostonnais complex plutons (1.40–1.37 Ga). This assemblage was formed in a magmatic arc setting. The sequence was intruded by mafic–ultramafic tholeiitic plutons, some of which host Ni–Cu ± PGE (platinum group element) prospects. U–Pb zircon ages determined from these plutons indicate that the mineralized intrusions were emplaced between 1.40 and 1.39 Ga and that they are coeval with the La Bostonnais complex plutons. The Ni–Cu ± PGE-bearing intrusions have mature island-arc trace element signatures, with strong chemical evidence for differentiation (Mg# and Cr content; MgO and TiO2 contents) and crustal contamination (enrichments in K2O, Rb, Ba, Th, and light rare-earth elements; Th/Yb and Ta/Yb ratios). However, one intrusion displays a back-arc trace element signature associated with evidence for weak crust assimilation. The evolution of the Portneuf–Mauricie Domain is interpreted as follows: (1) 1.45 Ga — Northwesterly directed Andean-type subduction beneath the Laurentian craton margin. Furthermore, northwest-dipping intraoceanic subduction offshore from the continent formed the Montauban island arc. (2) 1.45 to 1.40 Ga — Andean-type subduction led to the formation of a back-arc basin behind the Montauban arc. (3) 1.40 Ga — Emplacement of the La Bostonnais complex plutons, some hosting Ni–Cu ± PGE prospects, into the Montauban arc. (4) 1.39 Ga — Subduction beneath Laurentia led to arc–continent collision and to closure of the back-arc basin. Intrusion of the Ni–Cu ± PGE-bearing plutons ceased. (5) 1.37 Ga — Intrusion of all La Bostonnais complex plutons ceased.

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