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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Nd, Pb, and Sr isotope composition of juvenile magmatism in the Mesozoic large magmatic province of northern Chile (18-27 S): indications for a uniform subarc mantle
Friedrich Lucassen,Wolfgang Kramer,Viola Bartsch,Hans-Gerhard Wilke,Gerhard Franz,Rolf L. Romer,Peter Dulski +6 more
TL;DR: In this article, chemical and isotope compositions of mainly mafic to intermediate volcanic and intrusive rock units coherently indicate the generation of the juvenile magmas in a subduction regime and the dominance of a depleted subarc mantle source over contributions of the ambient Palaeozoic crust.
Journal ArticleDOI
Geology, geochronology, and geochemistry of the Miocene–Pliocene Ancestral Cascades arc, northern Sierra Nevada, California and Nevada: The roles of the upper mantle, subducting slab, and the Sierra Nevada lithosphere
TL;DR: The assemblage of ca. 28-3 Ma volcanic rocks exposed in the Lake Tahoe-Reno region of the northern Sierra Nevada, United States, is interpreted to be part of the Ancestral Cascades volcanic arc as mentioned in this paper.
Journal ArticleDOI
Contamination of basaltic magma by mafic crust at Amboy and Pisgah Craters, Mojave Desert, California
TL;DR: The authors of as mentioned in this paper show that the high-MgO component most likely is a primitive mantle-derived magma, based in part on its similarity to nearby xenolith-bearing Quaternary basalts.
Journal ArticleDOI
Sr, Nd, and Pb isotope evidence for open system evolution at Vulcano, Aeolian Arc, Italy
TL;DR: In this paper, isotopic (Sr, Nd, and Pb) and geochemical data are discussed with the aim of developing a model for the evolution of the magmatic system of Vulcano (Aeolian Arc, Italy).
Book ChapterDOI
Magma-crust interactions and magma plumbing in a postcollisional setting: Geochemical evidence from the Erzurum-Kars volcanic plateau, eastern Turkey
TL;DR: In this article, the authors describe a systematic temporal variation in volcanic activity all over the Erzurum-Kars plateau that can be seen in terms of three stages: it initiated with bimodal volcanic products between 11 and 6 Ma, turned abruptly into a unimodal intermediate volcanism dominated by andesitic lavas between 6 and 5 Ma, and finally reverted to bimodic activity between 5 and 1.5 Ma (the late stage).
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.
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.