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	Mei Xue Graduate student 289 McCone Hall Berkeley, CA 94720 (510)643-5450 (O) Email: meixue@ seismo.berkeley.edu

	Berkeley Seismology Lab
	Earth & Planetary Science
	UC Berkeley

Iceland upwelling: view from seismic anisotropy

		Iceland is a hotspot located on the North Atlantic Ridge, with the Reykjanes Ridge to the south and the Kolbeinsey Ridge to the north. This special location makes Iceland an ideal place to study the interactions between hotspot upwelling and mid-ocean ridge processes. The influence of the Iceland upwelling extends down the Kolbeinsey and Reykjanes ridges to the north and south of Iceland. A V-shaped pattern of bathymetry and gravity anomalies is observed along both the Reykjanes Ridge and on the eastern side of the Kolbeinsey Ridge.Geochemical signatures show that both the Reykjanes Ridge and the Kolbeinsey Ridge are affected by the Iceland upwelling.

	A V-shaped pattern of bathymetry


Radial flow or rift-parallel flow?

Radial flow and rift-parallel flow have been suggested as two candidate dispersion patterns of upwelling material when it arrives the base of the lithosphere. In radial flow, material spreads out in all directions away from the upwelling axis, whereas in rift-parallel flow, upwelling material flows parallel to the ridges. Both of these two geometries can generate the observed V-shaped pattern of bathymetry.

The proposed ridge-channeled flow model
			Our observed anisotropy pattern beneath Iceland (shown as short and thick black lines) reveals the horizontal flow of upwelling material toward and then down the North Atlantic Ridge. Material initially flows from the axis of upwelling beneath southeast Iceland to the northwest in what might be considered as ridge perpendicular flow from an off-ridge hotspot toward the ridge. Material then flows to the north and southwest down the Kolbeinsey and Reykjanes ridges respectively. These observations are consistent with the observed generation of V-shaped ridges along the Reykjanes and Kolbeinsey ridges due to channeling of upwelling material down the ridges.
See detailed information at: Xue, M. and R.M. Allen., Asthenospheric channeling of the Iceland upwelling: Evidence from seismic anisotropy, Earth Planet. Sci. Lett. 235, 167-182 doi:10.1016/j.epsl.2005.03.017. abstract \| reprint