Early Tertiary basalts from the Labrador Sea floor and Davis Strait region

Autor:	B. I. Cameron, D. B. Clarke, G. K. Muecke, J. L. Bates
Rok vydání:	1989
Předmět:	Basalt geography geography.geographical_feature_category Olivine Continental crust engineering.material Mantle (geology) Volcanic rock Petrography Oceanography engineering General Earth and Planetary Sciences Seawater Geology Seabed
Zdroj:	Canadian Journal of Earth Sciences. 26:956-968
ISSN:	1480-3313 0008-4077
DOI:	10.1139/e89-077
Popis:	Fine- to medium-grained, phyric and aphyric basalt samples from ODP Leg 105, site 647A, in the Labrador Sea show little evidence of alteration. Chemically, these rocks are low-potassium (0.01–0.09 wt.% K2O), olivine- to quartz-normative tholeiites that compare closely with the very depleted terrestrial Paleocene volcanic rocks in the Davis Strait region of Baffin Island and West Greenland. However, differences exist in the Sr–Nd isotope systematics of the two suites; the Labrador Sea samples have ε Nd values (+9.3) indicative of a more depleted source, and are higher in 87Sr/86Sr (0.7040), relative to the Davis Strait basalts (ε Nd +2.54 to +8.97; mean 87Sr/86Sr 0.7034). The higher 87Sr/86Sr in the Labrador Sea samples may reflect seawater exchange despite no petrographic evidence for significant alteration. The Labrador Sea and early Davis Strait basalts may have been derived from a similar depleted mantle source composition; however, the later Davis Strait magmas were generated from a different mantle. None of the Baffin Island, West Greenland, or Labrador Sea samples show unequivocal geochemical evidence for contamination with continental crust.
Databáze:	OpenAIRE
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