Journal ArticleDOI
A large-scale isotope anomaly in the Southern Hemisphere mantle
Reads0
Chats0
TLDR
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
Citations
More filters
Journal ArticleDOI
Secular Geochemistry of Central Puerto Rican Island Arc Lavas: Constraints on Mesozoic Tectonism in the Eastern Greater Antilles
TL;DR: In this paper, the authors show that the degree of incompatible element enrichment gradually increases as a result of subduction of a thickening accumulation of pelagic sediment, indicating the compositional evolution of the first four volcanic phases.
Journal ArticleDOI
Isotopic geochemistry of Fernando de Noronha
TL;DR: The Fernando de Noronha volcanic and hypabyssal rocks from the western equatorial Atlantic Ocean can generally be divided into two age-compositional groups that have variable and distinct isotopic compositions as mentioned in this paper.
Journal ArticleDOI
Sr, Nd and Pb isotope and geochemical data from the Quaternary Nevado de Toluca volcano, a source of recent adakitic magmatism, and the Tenango Volcanic Field, Mexico
Raymundo G. Martínez-Serrano,Peter Schaaf,Gabriela Solís-Pichardo,Ma. del Sol Hernández-Bernal,Teodoro Hernández-Treviño,Juan Morales-Contreras,José Luis Macías +6 more
TL;DR: In this paper, the authors investigated the role of the Plio-Quaternary E-W system in the ascent and storage of pyroclastic materials at Nevado de Toluca (NT) volcano.
Journal ArticleDOI
Hafnium isotope evidence for the origin of Cenozoic basaltic lavas from the southwestern United States
Brian L. Beard,Clark M. Johnson +1 more
TL;DR: In this article, the authors used the Hf-Hafnium isotope Hafnium analyses of 52 Cenozoic basalts from the southwestern United States to demonstrate the differences and similarities of the mantle beneath the continents, as compared to the suboceanic mantle.
Journal ArticleDOI
Nature of the depleted upper mantle beneath the Atlantic: evidence from Hf isotopes in normal mid-ocean ridge basalts from 79°N to 55°S
TL;DR: In this paper, a survey of the mid-Atlantic ridge basalts is presented, showing a very regular decrease in 176 Hf/ 177 Hf from 79j Nt o 55jS.
References
More filters
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.
Journal ArticleDOI
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.