PETROCHEMISTRY OF JURASSIC AND CRETACEOUS THOLEIITES FROM KONG-KARLS LAND, SVALBARD, AND THEIR RELATION TO MESOZOIC MAGMATISM IN THE ARCTIC

A study of the whole-rock geochemistry and mineral chemistry of high-T iO2 Upper Jurassic and medium-TiO2 Lower Cretaceous basalts from Kong Karls Land, Svalbard, is presented. Geochemical criteria indicate that the basalts are initial rifting tholeiites with weak signs of crustal contamination. The Upper Jurassic basalts appear to be associated wit h the Olga Rift, part of a trans-Barents rift system which failed to l ink the proto-Atlantic and proto-Arctic basins. The Lower Cretaceous b asalts may be more closely related to initial rifting tholeiites on Fr anz Josef Land and Spitsbergen generated during the rifting stage of o pening of the Canada Basin. During break-up of the Barents Shelf, the sequence of magma types corresponds to the pre-, syn-and post-rifting stages established in other areas of continental break-up. Evidence fo r a possible hot-spot or plume trail, extending from Siberia to the Ye rmak Plateau over 250 Ma, is assembled.