Upper Jurassic tholeiitic basalts from DSDP leg 11
| Autor: | A. E. Bence, S. R. Taylor, R. A. Ayuso |
|---|---|
| Rok vydání: | 1976 |
| Předmět: |
Atmospheric Science
Geochemistry Soil Science Aquatic Science engineering.material Oceanography Petrography Geochemistry and Petrology Earth and Planetary Sciences (miscellaneous) Plagioclase Mesozoic Earth-Surface Processes Water Science and Technology Basalt geography geography.geographical_feature_category Olivine Ecology Paleontology Drilling Forestry Mid-ocean ridge Geophysics Space and Planetary Science Ridge (meteorology) engineering Geology |
| Zdroj: | Journal of Geophysical Research. 81:4305-4325 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/jb081i023p04305 |
| Popis: | Basalts recovered from sites 100 and 105 of leg 11 of the Deep-Sea Drilling Project are mineralogically and chemically similar to basalts recovered from ridge and near-ridge sites. Textural evidence suggests that the units sampled were extruded as thin flows and are presumably the products of midocean ridge volcanism shortly after the opening of the North Atlantic in the middle to late Jurassic. Chemical evolution of the liquids sampled at site 105 has occurred as a consequence of the low-pressure fractionation of olivine and plagioclase. Site 100 basalts have experienced clinopyroxene fractionation, presumably at pressures in excess of about 10 kbar. Models for the abundances of incompatible trace elements in the source regions of these basalts suggest 2–3 times chondritic heavy rare earths at both sites, 0.5–1 times chondritic Zr, Hf, Nb, Y, and La at site 105, and 1–2 times chondritic Zr, Hf, and Nb at site 100. Two site 100 samples have variable La/Yb ratios which reflect inhomogeneities in the upper mantle. There is no indication that the source regions for North Atlantic midocean ridge basalts has evolved since the late Mesozoic. |
| Databáze: | OpenAIRE |
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