Skagi and western neovolcanic zones in Iceland: 2. Geochemical variations

Journal Article · Thu Aug 10 04:00:00 EDT 1978 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB083iB08p03983· OSTI ID:6685282

Schilling, J; Sigurdsson, H; Kingsley, R H

Rare-earth, Sc, V, Cr, Fe, Co, and Ni contents of basalts from the Skagi and western neovolcanic (Langjoekull, Thingveillir, and Reykjanes peninsula) zones of Iceland are reported. In comparison to the Langjoekull zone, which is dominated by olivine tholeiites, the Skagi zone is characterized by a uniform tholeiitic basalt province significantly higher in Fe, Na, Ti, P, K, Fe*/(Fe*+Mg), La/Sm, and large-ion lithophile trace elements with bulk crystal-melt partition coefficients Dvery-much-less-than1 (La, K, and P) and lower in Mg, Ca, and trace elements, with D>1 (Ni and Cr); however, Co, with Dapprox. =1, remains practically constant throughout the zones. Basalts from the Reykjanes peninsula are generally intermediate between those from the Skagi and the Langjoekull zone, and those from the Thingvellir zone resemble mostly those from Langjoekull. The petrologic and geochemical discontinuity between Skagi and Langjoekull is abrupt and apparently coincides with steepening of existing geothermal gradients and thickening of the Iceland crust from south to north, as well as with an age discontinuity. On the other hand, variation along the neovolcanic zone from the Langjoekull-Thingvellir zone to the Reykjanes peninsula and the Reykjanes Ridge are gradational. Fractionation processes involving crystal and melt are primarily responsible for the compositional variations observed along these zones. Modeling suggest that the most primitive melts of the four zones can be derived by variable degrees of melting of a relatively homogeneous lherzolite mantle source with an approximately chondritic relative RE pattern but enriched 4-6 times, thus clearly distinct from the LRE-Depleted mantle source of 'normal' ridge basalts sourth and north of Iceland. Estimated degrees of melting range 8-10% for Skagi, 18-20% for the Reykjanes peninsula, and 30-50% for the Thingvellir and Langjoekull zones.

• Research Organization: Graduate School of Oceanography, University of Rhode Island, Kingston, Rhode Island 02881
• OSTI ID: 6685282
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 83:B8; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580202* -- Geophysics-- Volcanology-- (1980-1989)
BASALT
CHEMISTRY
CHONDRITES
ELEMENTS
EUROPE
GEOCHEMISTRY
GEOTHERMAL GRADIENTS
ICELAND
IGNEOUS ROCKS
MELTING
METALS
METEORITES
PHASE TRANSFORMATIONS
RARE EARTHS
ROCKS
STONE METEORITES
TEMPERATURE GRADIENTS
TRANSITION ELEMENTS
VOLCANIC REGIONS
VOLCANISM