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 and trace element geochemistry of Colorado Plateau volcanics
TL;DR: Basalts from the San Francisco Peaks and North Rim of Grand Canyon, nephelinites from the Hopi Buttes and Navajo minettes (Colorado Plateau) have been analyzed for trace element contents and Sr, Nd, Pb isotope compositions as discussed by the authors.
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Two contrasting magmatic types coexist after the cessation of back-arc spreading
TL;DR: In this paper, the authors present new age, chemical and isotopic data from the hitherto unexplored seamounts which formed furthest from the active volcanic front, which are found to be contemporaneous with the back-arc seamount chains and the East Shikoku Basin seamount.
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Comparative geochemistry of West African kimberlites: Evidence for a micaceous kimberlite endmember of sublithospheric origin
TL;DR: A suite of largely unaltered, aphanitic, mica-bearing hypabyssal kimberlites from the Koidu Kimberlite complex of the West African Craton have been investigated to determine their geochemical affinity relative to Group I (non-micaceous) and Group II (micaceous), in this article.
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Melt-generation processes associated with the Tristan mantle plume: Constraints on the origin of EM-1
TL;DR: In this article, the authors present new geochemical data for OIB samples from the central South Atlantic; these include 100 to 30 Ma alkali and tholeiitic basalts from the Walvis Ridge and Rio Grande Rise and < 3 Ma basanites and basalts of Tristan da Cunha, Inaccessible and Gough.
Journal ArticleDOI
Geochemical evidence for plume—mantle interactions beneath Kerguelen and Heard Islands, Indian Ocean
Michael Storey,Ad D. Saunders,John Tarney,Philip T. Leat,Matthew F. Thirlwall,Robert N. Thompson,Martin Menzies,Gf F. Marriner +7 more
TL;DR: In this article, the isotopic compositions of Kerguelen basalts vary in sympathy with this changing tectonic environment, and suggest not only that depleted asthenosphere, but also that Cretaceous oceanic plateau litho-sphere, may have contributed significantly to the earlier magmatic history of the island.
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.