Plume-driven plumbing and crustal formation in Iceland

• Main Authors: Richard M. Allen, Guust Nolet, W. Jason Morgan, Kristín Vogfjörd, Meredith Nettles, Göran Ekström, Bergur H. Bergsson, Pálmi Erlendsson, G. R. Foulger, Steinunn Jakobsdóttir, Bruce R. Julian, Matt Pritchard, Sturla Ragnarsson, Ragnar Stefánsson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Hekla; Iceland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.412.424; http://seismo.berkeley.edu/~rallen/pub/2001icecrust/Allen2002IcelandCrustJGR.pdf

[1] Through combination of surface wave and body wave constraints we derive a threedimensional (3-D) crustal S velocity model and Moho map for Iceland. It reveals a vast plumbing system feeding mantle plume melt into upper crustal magma chambers where crustal formation takes place. The method is based on the partitioned waveform inversion to which we add additional observations. Love waves from six local events recorded on the HOTSPOT-SIL networks are fitted, Sn travel times from the same events measured, previous observations of crustal thickness are added, and all three sets of constraints simultaneously inverted for our 3-D model. In the upper crust (0–15 km) an elongated low-velocity region extends along the length of the Northern, Eastern and Western Neovolcanic Zones. The lowest velocities ( 7%) are found at 5–10 km below the two most active volcanic complexes: Hekla and Bárdarbunga-Grímsvötn. In the lower crust (>15 km) the low-velocity region can be represented as a vertical cylinder beneath central Iceland. The low-velocity structure is interpreted as the thermal halo of pipe work which connects the region of melt generation in the uppermost mantle beneath central Iceland to active volcanoes along the neovolcanic zones. Crustal thickness in