Geochemical provincialism in the Iceland plume

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Shorttle, Oliver, Maclennan, John, Piotrowski, Alexander M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Published by Elsevier B.V. 2013
• Subjects: 02 - Geodynamics; Geophysics and Tectonics; Iceland
• Online Access: http://eprints.esc.cam.ac.uk/2892/; http://eprints.esc.cam.ac.uk/2892/7/1-s2.0-S0016703713004845-main.pdf; http://eprints.esc.cam.ac.uk/2892/8/1-s2.0-S0016703713004845-gr1.jpg; http://eprints.esc.cam.ac.uk/2892/9/mmc1.csv; http://www.sciencedirect.com/science/article/pii/S0016703713004845; https://doi.org/10.1016/j.gca.2013.08.032

We present new Pb-Sr-Nd isotope, major and trace element data for a suite of basalts from central Iceland. We combine this new data with existing sample sets and interrogate it using spatial statistical methods. On the View the MathML source scale of a volcanic zone we find strong correlation between the three isotope systems. However, on greater length scales we identify two types of spatial structure, both of which are most strongly observed in the Pb isotopes. Firstly, the mean Pb-isotopic composition of basalts becomes progressively less radiogenic from south to north Iceland, with our central Iceland dataset falling at intermediate compositions. Secondly, there is a shift in the pseudo-binary mixing array that samples fall along as the neovolcanic zones are stepped through south to north, both in Pb-Pb, and Pb-Sr/Nd isotope space. The Pb isotope systematics of Icelandic basalts therefore appear to be decoupled from those of Sr and Nd isotopes on length scales View the MathML source. Only within individual neovolcanic zones are there coherent relationships between the Pb, Sr and Nd isotopic compositions of basalts. The spatial structure uniquely recorded by Pb isotopes complements observations from previous authors that Pb isotope dynamics are fundamentally distinct from other isotope systems.