Journal ArticleDOI
A large-scale isotope anomaly in the Southern Hemisphere mantle
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The authors showed that the isotopic mantle anomaly is globe-encircling in extent, centred on latitude 30° S. They also showed that this mantle anomaly has been in existence for billions of years and placed severe constraints on mantle convection models.Abstract:
Basalts from many Southern Hemisphere regions have anomalous Sr and Pb isotopic characteristics. This article shows that the isotopic mantle anomaly is globe-encircling in extent, centred on latitude 30° S. Arguments suggesting that this mantle anomaly has been in existence for billions of years place severe constraints on mantle convection models.read more
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Isotope characteristics of the Okenyenya igneous complex, northwestern Namibia: constraints on the composition of the early Tristan plume and the origin of the EM 1 mantle component
Simon C. Milner,Anton P. le Roex +1 more
TL;DR: In this article, a variety of intrusive rocks from the Mesozoic age Okenyenya igneous complex, which is temporally and spatially associated with the Etendeka Group volcanic rocks in northwestern Namibia, are presented.
Journal ArticleDOI
Major- and trace-element compositions of Cenozoic basalts in eastern China: Petrogenesis and mantle source
TL;DR: In this paper, the authors studied Cenozoic basalts from eastern China with SiO2 contents ranging from 38.63 to 55.24 wt%, and Na2O + K2O from 3.1 to 9.4 wt%.
Journal ArticleDOI
The geochemical structure of the South-East Indian Ridge
TL;DR: Isotopic (Sr, Nd, Pb) and trace element data are reported for samples dredged along the South-East Indian Ridge (SEIR) and confirm the existence of a geochemical province under the Indian Ocean which is distinct from the provinces observed under the North Atlantic and Pacific Oceans.
Journal ArticleDOI
Geochemistry of the mantle beneath the Rodriguez Triple Junction and the South-East Indian Ridge
TL;DR: In this article, Pb isotope compositions have been measured on zero-age dredge samples from the Rodriguez Triple Junction (RTJ) and the South-East Indian Ridge (SEIR), along the SEIR.
Journal ArticleDOI
Magmatism in the South China Basin: 2. Post-spreading Quaternary basalts from Hainan Island, south China
TL;DR: In this article, it is proposed that EM2 derives from sub-continental lithosphere or asthenosphere reservoirs, enriched by subduction prior to crustal extension, and that Hainan basalts resemble Dupal-type oceanic island basalt and reflect mixing of EM2 and N-MORB mantle reservoirs.
References
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Journal ArticleDOI
Mantle plumes from ancient oceanic crust
TL;DR: In this article, the authors propose a model for the origin of hot-spot volcanism, where oceanic crust is returned to the mantle during subduction and sinks into the deeper mantle and accumulates at some level of density compensation, possibly the core-mantle boundary.
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Lead isotopic study of young volcanic rocks from mid-ocean ridges, ocean islands and island arcs
TL;DR: Lead isotopic compositions of young volcanic rocks from different tectonic environments have distinctive characteristics their differences are evaluated within the framework of global tectonics and mantle differentiation Ocean island leads are in general more radiogenic than mid-ocean ridge basalt (morb) leads as discussed by the authors.
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Ore lead isotope ratios in a continuously changing earth
G.L. Cumming,J.R. Richards +1 more
TL;DR: In this paper, a critical re-assessment of the construction of simple ore lead isotopic development curves is followed by three fresh approximations, all designed to involve the minimum possible number of assumptions.
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Sr and Nd isotope geochemistry of oceanic basalts and mantle evolution
TL;DR: Sr and Nd isotope ratios for 17 mid-ocean ridge basalts and for 11 oceanic islands and island groups are reported in this article, and the results are not explained by binary mixing of depleted and undepleted mantle reservoirs or variable magmatic depletion of a planetary reservoir, but support mantle evolution models involving re-injection of crust material into the mantle.
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Pb–Sr isotope variation in Indian Ocean basalts and mixing phenomena
Bernard Dupré,Claude J. Allègre +1 more
TL;DR: Pb and Sr isotopic compositions from the Indian Ocean (active ridges, old ocean floor and aseismic ridge samples) confirm the characteristic nature of the mantle record in this region as mentioned in this paper.