کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6430408 1634793 2012 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
How double volcanic chains sample geochemical anomalies from the lowermost mantle
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
How double volcanic chains sample geochemical anomalies from the lowermost mantle
چکیده انگلیسی

The distinct isotopic compositions of basalts from the two parallel tracks of Hawaiian volcanoes suggest a bilateral zonation of the underlying mantle plume, with an enriched southern side. Such zonation is not unique to Hawaii, but may well be a common feature of other Pacific hotspots. This remarkable isotopic pattern, revealed by double volcanic chains, appears to be related to the so-called DUPAL isotopic anomaly in the Pacific mantle, which correlates with the seismically imaged 'Large Low-Shear-Velocity Province'. Here we show how a large-scale isotopic gradient, exemplified by the radiogenic isotope ratio Pb⋆208/Pb⋆206, maps from the deep mantle into the Hawaiian plume conduit, and how it ultimately surfaces as Pb⋆208/Pb⋆206 variations in double-chain volcanoes. Our numerical simulations reveal a novel 'lobate' conduit structure which generates an overall bilateral isotopic zonation within the Hawaiian melting zone. Comparison between our model predictions and Pb⋆208/Pb⋆206 of several Hawaiian volcanoes shows that a deep-seated, north-south, isotopic gradient can explain the enriched southern (Loa) chain as well as the Pb⋆208/Pb⋆206 decline from shield to post-shield lavas, observed in several of the volcanoes. The results provide a mechanism for directly linking geochemical maps of ocean island basalts to the structure and composition of the lowermost mantle inferred by seismic tomography.

Graphical Abstract499Highlights► We model large-scale (DUPAL-like) geochemical gradients in the lower mantle. ► We find a novel 'lobate' geochemical zonation of the plume conduit. ► We model the flow of the Hawaiian plume and map Pb⋆208/Pb⋆206. ► We explain Pb⋆208/Pb⋆206 differences between Loa and Kea-trend volcanoes. ► We explain the Pb⋆208/Pb⋆206 shield post-shield evolution of Big Island volcanoes.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volumes 359–360, 15 December 2012, Pages 240-247
نویسندگان
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