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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Petrogenesis of Late Cenozoic mafic alkaline rocks of the Nosy Be archipelago (northern Madagascar): relationships with the Comorean magmatism
TL;DR: In this paper, the results of a geochemical and isotopic (Sr-Nd-Pb) study of mafic volcanic rocks outcropping in the Nosy Be archipelago are reported.
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Post-collisional Plio-Pleistocene shoshonitic volcanism in the western Kunlun Mountains, NW China: Geochemical constraints on mantle source characteristics and petrogenesis
TL;DR: In this paper, the major and trace element, Sr−Nd−Pb isotope and mineral chemical data are presented for post-collisional late Cenozoic shoshonitic volcanic rocks from the western Kunlun Mountains, NW China.
Journal ArticleDOI
Mixing in the Mantle
TL;DR: The mid-ocean ridge basalts (MORB) are depleted in trace elements due to the extraction of the crust, which is correspondingly enriched as discussed by the authors, indicating that the source region for these basalts has been depleted for some time (several billion years).
Journal ArticleDOI
Petrogenesis of Challis volcanics from central and southwestern Idaho: Trace element and Pb isotopic evidence
TL;DR: In this article, an analysis of the lava flows and ash-flow tuffs in Idaho is conducted to determine the composition of the volcanics in terms of major and trace elements and Pb isotopic substances.
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The composition of back-arc basin lower crust and upper mantle in the Mariana Trough : A first report
TL;DR: In this article, a single dredge haul from the deepest 5.5 km of the Mariana Trough was used to recover a heterogeneous suite of volcanic and plutonic crustal rocks and upper mantle peridotites.
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.