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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Radiogenic isotopes document the start of subduction in the Western Pacific
Hongyan Li,Rex N. Taylor,Julie Prytulak,Maria Kirchenbaur,John W. Shervais,Jeffrey G. Ryan,Marguerite Godard,Mark K. Reagan,Julian A. Pearce +8 more
TL;DR: In this paper, the authors used Hf-Nd-Sr-Pb isotope analyses from 50 core samples to trace the evolution of the mantle source during the brief period of FAB-through-boninite magmatism immediately following subduction initiation.
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Geochemical and isotopic (Sr, Nd, Pb) evidence for plume–lithosphere interactions in the genesis of Grande Comore magmas (Indian Ocean)
TL;DR: In this paper, three groups of Grande Comore lavas, namely, old Karthala, recent Karthla and La Grille, were distinguished among the major and trace element data, with a clear distinction between these lavas (shield-stage) and strongly undersaturated primary melts (post-shield stage).
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Termination time of peak decratonization in North China: Geochemical evidence from mafic igneous rocks
TL;DR: In this paper, two types of mafic igneous rocks with contrasting geochemical compositions from North China were studied, and they were found to have arc-like trace element distribution patterns and enriched radiogenic Sr-Nd isotope compositions, with emplacement ages spanning from the Triassic to Early Cretaceous.
Journal ArticleDOI
Coats Land dolerites and the generation of Antarctic continental flood basalts
TL;DR: On the basis of geochemical signatures, Mesozoic magmatism in Antarctica is divided into the Ferrar Magmatic Province and the Dronning Maud Land Province as discussed by the authors, and the transition between these two geochemical provinces is located in Coats Land.
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Extension-related origin of magmas from a garnet-bearing source in the Los Tuxtlas volcanic field, Mexico
TL;DR: The Los Tuxtlas volcanic field (LTVF) of late Miocene to Recent age is a key area to understand the consequences of the current subduction of the Cocos plate beneath the North American plate, as well as the competing effects of the ongoing extension along the Gulf of Mexico coast Geochemical and radiogenic (Sr, Nd, and Pb) isotope data from the LTVF are used to constrain the origin of these 7 Ma to Recent magmas in this area as mentioned in this paper.
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.