scholarly journals Unravelling lunar mantle source processes via the Ti isotope composition of lunar basalts

2020 ◽  
pp. 13-18 ◽  
Author(s):  
S. Kommescher ◽  
R.O.C. Fonseca ◽  
F. Kurzweil ◽  
M.M. Thiemens ◽  
C. Münker ◽  
...  
Keyword(s):  
Mantle Source ◽  
Isotope Composition ◽  
Lunar Basalts

scholarly journals Sunda arc mantle source δ18O value revealed by intracrystal isotope analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Frances M. Deegan ◽  
Martin J. Whitehouse ◽  
Valentin R. Troll ◽  
Harri Geiger ◽  
Heejin Jeon ◽  
...  
Keyword(s):  
Mantle Source ◽  
Secondary Ion Mass Spectrometry ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Sunda Arc ◽  
Mid Ocean Ridge ◽  
Plumbing Systems ◽  
Ocean Ridge ◽  
Secondary Ion ◽  
Magma Plumbing

AbstractMagma plumbing systems underlying subduction zone volcanoes extend from the mantle through the overlying crust and facilitate protracted fractional crystallisation, assimilation, and mixing, which frequently obscures a clear view of mantle source compositions. In order to see through this crustal noise, we present intracrystal Secondary Ion Mass Spectrometry (SIMS) δ18O values in clinopyroxene from Merapi, Kelut, Batur, and Agung volcanoes in the Sunda arc, Indonesia, under which the thickness of the crust decreases from ca. 30 km at Merapi to ≤20 km at Agung. Here we show that mean clinopyroxene δ18O values decrease concomitantly with crustal thickness and that lavas from Agung possess mantle-like He-Sr-Nd-Pb isotope ratios and clinopyroxene mean equilibrium melt δ18O values of 5.7 ‰ (±0.2 1 SD) indistinguishable from the δ18O range for Mid Ocean Ridge Basalt (MORB). The oxygen isotope composition of the mantle underlying the East Sunda Arc is therefore largely unaffected by subduction-driven metasomatism and may thus represent a sediment-poor arc end-member.

Chlorine isotope composition of volcanic gases and rocks at Mount Etna (Italy) and inferences on the local mantle source

2013 ◽  
Vol 371-372 ◽  
pp. 134-142 ◽  
Author(s):  
Andrea L. Rizzo ◽  
Antonio Caracausi ◽  
Marcello Liotta ◽  
Antonio Paonita ◽  
Jaime D. Barnes ◽  
...  
Keyword(s):  
Mantle Source ◽  
Isotope Composition ◽  
Mount Etna ◽  
Volcanic Gases ◽  
Chlorine Isotope

scholarly journals Remnants of early Earth differentiation in the deepest mantle-derived lavas

2020 ◽  
Vol 118 (1) ◽  
pp. e2015211118
Author(s):  
Andrea Giuliani ◽  
Matthew G. Jackson ◽  
Angus Fitzpayne ◽  
Hayden Dalton
Keyword(s):  
Mantle Source ◽  
Isotope Composition ◽  
Volcanic Rocks ◽  
Primitive Mantle ◽  
Early Earth ◽  
Apparent Contradiction ◽  
Ocean Island ◽  
Melt Extraction ◽  
Ocean Island Basalts ◽  
Isotopic Compositions

The noble gas isotope systematics of ocean island basalts suggest the existence of primordial mantle signatures in the deep mantle. Yet, the isotopic compositions of lithophile elements (Sr, Nd, Hf) in these lavas require derivation from a mantle source that is geochemically depleted by melt extraction rather than primitive. Here, this apparent contradiction is resolved by employing a compilation of the Sr, Nd, and Hf isotope composition of kimberlites—volcanic rocks that originate at great depth beneath continents. This compilation includes kimberlites as old as 2.06 billion years and shows that kimberlites do not derive from a primitive mantle source but sample the same geochemically depleted component (where geochemical depletion refers to ancient melt extraction) common to most oceanic island basalts, previously called PREMA (prevalent mantle) or FOZO (focal zone). Extrapolation of the Nd and Hf isotopic compositions of the kimberlite source to the age of Earth formation yields a143Nd/144Nd-176Hf/177Hf composition within error of chondrite meteorites, which include the likely parent bodies of Earth. This supports a hypothesis where the source of kimberlites and ocean island basalts contains a long-lived component that formed by melt extraction from a domain with chondritic143Nd/144Nd and176Hf/177Hf shortly after Earth accretion. The geographic distribution of kimberlites containing the PREMA component suggests that these remnants of early Earth differentiation are located in large seismically anomalous regions corresponding to thermochemical piles above the core–mantle boundary. PREMA could have been stored in these structures for most of Earth’s history, partially shielded from convective homogenization.

Corrigendum to “The Fe and Zn isotope composition of deep mantle source regions: Insights from Baffin Island picrites” [Geochim. Cosmochim. Acta 238 (2018) 542–562]

2019 ◽  
Vol 259 ◽  
pp. 414-415
Author(s):  
Alex J. McCoy-West ◽  
J. Godfrey Fitton ◽  
Marie-Laure Pons ◽  
Edward C. Inglis ◽  
Helen M. Williams
Keyword(s):  
Mantle Source ◽  
Isotope Composition ◽  
Baffin Island ◽  
Source Regions ◽  
Deep Mantle

Long-Lasting (65 Ma) Regionally Contrasting Late- to Post-Orogenic Variscan Mantle-derived Potassic Magmatism in the Bohemian Massif

2020 ◽  
Vol 61 (7) ◽  
Author(s):  
Lukáš Krmíček ◽  
Rolf L Romer ◽  
Martin J Timmerman ◽  
Jaromír Ulrych ◽  
Johannes Glodny ◽  
...  
Keyword(s):  
Mantle Source ◽  
Bohemian Massif ◽  
Isotope Composition ◽  
Small Variation ◽  
Source Rocks ◽  
Calc Alkaline ◽  
Magmatic Rocks ◽  
Depleted Mantle ◽  
Pb Isotopic Composition ◽  
Alkaline Lamprophyres

Abstract The orogenic development after the continental collision between Laurussia and Gondwana, led to two contrasting associations of mantle-derived magmatic rocks on the territory of the Bohemian Massif: (i) a 340–310 Ma lamprophyre-lamproite orogenic association; and (ii) a 300–275 Ma lamprophyre association of anorogenic affinity. Major types of potassic mantle-derived magmatic rocks recognized in the orogenic and anorogenic associations include: (i) calc-alkaline to alkaline lamprophyres; (ii) alkaline ‘orthopyroxene minettes’ and geochemically related rocks grouped here under the new term lampyrite; and (iii) peralkaline lamproites. These three types significantly differ with respect to mineral, whole-rock and Sr–Nd–Pb–Li isotope composition and spatial distribution. The calc-alkaline lamprophyres occur throughout the entire Saxo-Thuringian and Moldanubian zones, whereas the different types of malte-derived potassic rocks are spatially restricted to particular zones. Rocks of the Carboniferous lamprophyre-lamproite orogenic association are characterized by variable negative εNd(i) and variably radiogenic Sr(i), whereas the rocks of the Permian lamprophyre association of anorogenic affinity are characterized by positive εNd(i) and relatively young depleted-mantle Nd-model ages reflecting increasing input from upwelling asthenospheric mantle. The small variation in the Pb isotopic composition of post-collisional potassic mantle-derived magmatic rocks (of both the orogenic and anorogenic series) implies that the Pb budget of the mantle beneath the Bohemian Massif is dominated by the same crust-derived material, which itself may include material derived from several sources. The source rocks of ‘orthopyroxene minettes’ are characterized by isotopically light (‘eclogitic’) Li and strongly radiogenic (crustal) Sr and may have been metasomatized by high-pressure fluids along the edge of a subduction zone. In contrast, the strongly Al2O3 and CaO depleted mantle source of the lamproites is characterized by isotopically heavy Li and high SiO2 and extreme K2O contents. This mantle source may have been metasomatized predominantly by melts. The mantle source of the lamprophyres may have undergone metasomatism by both fluids and melts.

scholarly journals Sulfur isotope composition of Ru-Os sulfides from the Verkh-Neivinsky dunite-harzburgite massif (Middle Urals, Russia): new data

2019 ◽  
Vol 488 (2) ◽  
pp. 185-188
Author(s):  
V. V. Murzin ◽  
I. Yu. Badanina ◽  
K. N. Malitch ◽  
A. V. Ignatiev ◽  
T. A. Velivetskaya
Keyword(s):  
Mantle Source ◽  
Sulfur Isotope ◽  
Isotope Composition ◽  
Platinum Group Mineral ◽  
Middle Urals ◽  
Data Set ◽  
Group Mineral ◽  
The Middle Urals ◽  
Sulfur Isotope Composition ◽  
S Isotope

This study presents the first data set of sulfurisotope compositions of primary Ru-Os sulfides, represented by laurite (RuS2) - erlichmanite (OsS2) series, within a primary platinum-group mineral (PGM) assemblage derived from the Verkh-Neivinsky dunite-harzburgite massif, a typical example of the mantle ophiolite association at the Middle Urals. The S-isotope signatures of Ru-Os sulfides studied are consistent with derivation of the ore material from a mantle source for Ru-Os sulfides.

scholarly journals The Fe and Zn isotope composition of deep mantle source regions: Insights from Baffin Island picrites

2018 ◽  
Vol 238 ◽  
pp. 542-562 ◽  
Author(s):  
Alex J. McCoy-West ◽  
J. Godfrey Fitton ◽  
Marie-Laure Pons ◽  
Edward C. Inglis ◽  
Helen M. Williams
Keyword(s):  
Mantle Source ◽  
Isotope Composition ◽  
Baffin Island ◽  
Source Regions ◽  
Deep Mantle

scholarly journals Hafnium isotope composition of zircon from the Kondyor clinopyroxenite-dunite massif (Khabarovsk territory, Russia)

2019 ◽  
Vol 486 (5) ◽  
pp. 588-592
Author(s):  
I. Yu. Badanina ◽  
E. A. Belousova ◽  
K. N. Malitch
Keyword(s):  
Isotopic Composition ◽  
Mantle Source ◽  
Siberian Craton ◽  
Isotope Composition ◽  
Subcontinental Lithospheric Mantle ◽  
Basement Rocks ◽  
Magma Sources ◽  
Hf Isotopic Composition ◽  
T Values ◽  
First Time

This study evaluates for the first time Hf-isotope characteristics of zircon from dunite of the Kondyor massif, which is closely related to an economic platinum placer deposit. The significant range in εHf(t) values (from -8.4 ± 0.8 to 10.5 ± 1.3) in Mesozoic zircons indicates the interaction of a ‘juvenile’ mantle source with distinct magma sources, equivalent to a subcontinental lithospheric mantle and/or a continental crust. The peculiarities of the Hf-isotopic composition of Precambrian zircons (εHf(t) from -2.3 to +0.3) is consistent with their xenogenic origin and inheritance from basement rocks of the Siberian Craton.

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