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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Geochemical characteristics of lavas from Broken Ridge, the Naturaliste Plateau and southernmost Kerguelen Plateau: Cretaceous plateau volcanism in the southeast Indian Ocean☆
John J. Mahoney,W.B. Jones,Frederick A. Frey,Vincent J. M. Salters,Douglas G. Pyle,Hugh L Davies +5 more
TL;DR: Isotopic and incompatible-element ratios of the plateau lavas are distinct from those of Indian mid-ocean ridge basalts; their Nd, Sr, 207Pb 204Pb and 208Pb204Pb isotopic ratios overlap with but cover a much wider range than measured for more recent oceanic products of the Kerguelen hotspot (including the Ninetyeast Ridge) or, indeed, oceanic lavas from any other hotspot in the world as discussed by the authors.
Journal ArticleDOI
Pb, Sr, Nd, and Hf isotopic constraints on the origin of Hawaiian basalts and evidence for a unique mantle source
TL;DR: The isotopic Pb, Sr, Nd, and Hf compositions of nine Hawaiian volcanos were determined using the analytical procedures described by Tatsumoto and Unruh.
Journal ArticleDOI
Lithospheric to asthenospheric transition in Low-Ti flood basalts from southern Paraná, Brazil
TL;DR: In this paper, two geochemically distinct Low-Ti magma types (Gramado and Esmeralda) are distinguished within the flood basalt sequences of southern Parana on the basis of certain element abundances and ratios.
Journal ArticleDOI
Isotope evidence of a mantle convection boundary at the Australian-Antarctic Discordance
TL;DR: Basalts from the Southeast Indian Ridge south of Australia form two geographically and isotopically distinct groups that show affinities with either Indian Ocean or Pacific/Atlantic Ocean isotope compositions as mentioned in this paper.
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Origin of the Indian Ocean-type isotopic signature in basalts from Philippine Sea plate spreading centers: An assessment of local versus large-scale processes
TL;DR: In this paper, the authors show that the Indian Ocean mid-ocean ridge basalt (MORB) has the distinctive isotopic characteristics of the Philippine Sea plate upper mantle, such as high 208Pb/204Pb and low 143Nd/144Nd compared with Pacific and Atlantic Ocean MORB.
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.
Journal ArticleDOI
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.
Journal ArticleDOI
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.
Journal ArticleDOI
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.