Generation of porphyritic rift zone basalts in Iceland - Evidence from the Thjorsa lava Halldorsson, S. A. ; Gronvold, K. ; Oskarsson, N. ; Sigurdsson, G. ; Sverrisdottir, G. Abstract Publication: Geochimica et Cosmochimica Acta Supplement Pub Date: July 2008 Bibcode: 2008GeCAS..72R.343H