Conditions of melting beneath the Azores

Beitrag in einer Fachzeitschrift
(Originalarbeit)


Details zur Publikation

Autorinnen und Autoren: Beier C, Haase K, Turner SP
Zeitschrift: Lithos
Verlag: Elsevier
Jahr der Veröffentlichung: 2012
Seitenbereich: 1-11
ISSN: 0024-4937


Abstract


The depth and temperatures of melting beneath Ocean Islands provide important constraints on mantle melting dynamics. The central Azores islands of Faial, Pico, Graciosa and São Jorge are ideally suited for calculating depth and temperatures of melting because they are situated orthogonal to the slow spreading Mid-Atlantic Ridge and thus supposedly on variable lithosphere thicknesses which allow to constrain on the influence of lithosphere thickness on average melting depth. The dataset presented here is used to test the spatial pattern of potential temperature anomalies in the Azores mantle plume. Trace elements indicate comparable degrees of partial melting for all three islands, while Sr-Nd-Pb isotope ratios and incompatible trace element ratios imply only small-scale source heterogeneity that is not related to the major element systematics. Thus, the observed differences in calculated, primary SiO , FeO and TiO (and Al O ) are inferred to reflect changes in melting pressures and temperatures that are independent of source composition. Melting temperatures in the Azores are lower and melting starts deeper than at other mantle plumes (e.g., Hawaii). This implies that the smaller size of the Azores compared to other mantle plumes might be the result of a much smaller anomaly with a large variability of depths and temperatures of melting even on the scale of an individual island. This small-scale variability is of importance when comparing pressures and temperatures between different islands or even globally. The Azores lavas have temperatures lower than predicted for a dry mantle solidus indicating the presence of at least 200ppm H O in the Azores mantle source. © 2012 Elsevier B.V.



FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik
Haase, Karsten Prof. Dr.
Lehrstuhl für Endogene Geodynamik


Einrichtungen weiterer Autorinnen und Autoren

Macquarie University


Zitierweisen

APA:
Beier, C., Haase, K., & Turner, S.P. (2012). Conditions of melting beneath the Azores. Lithos, 1-11. https://dx.doi.org/10.1016/j.lithos.2012.02.019

MLA:
Beier, Christoph, Karsten Haase, and Simon P. Turner. "Conditions of melting beneath the Azores." Lithos (2012): 1-11.

BibTeX: 

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