نتایج جستجو برای: ocean ridge basalt
تعداد نتایج: 82934 فیلتر نتایج به سال:
The Paleocene-Eocene thermal maximum (PETM) has been attributed to a sudden release of carbon dioxide and/or methane. 40Ar/39Ar age determinations show that the Danish Ash-17 deposit, which overlies the PETM by about 450,000 years in the Atlantic, and the Skraenterne Formation Tuff, representing the end of 1 +/- 0.5 million years of massive volcanism in East Greenland, are coeval. The relative ...
Oceanic crust is a massive potential habitat for microbial life on Earth, yet our understanding of this ecosystem is limited due to difficulty in access. In particular, measurements of rates of microbial activity are sparse. We used stable carbon isotope incubations of crustal samples, coupled with functional gene analyses, to examine the potential for carbon fixation on oceanic crust. Both sea...
The Bandan chromite mine is the main chromite deposit in Sistan suture zone, eastrn Iran. The chromite deposits are structurally tabular to lens-shaped bodies hosted by dunitic to harzburgitic mantle peridotites. Similar to Alpine type podiform chromites, chromitite pods are enclosed within dunitic envelops. The chromites show mainly massive to disseminated and also brecciated textures. Chemica...
Sediment-covered basalt on the flanks of mid-ocean ridges constitutes most of Earth's oceanic crust, but the composition and metabolic function of its microbial ecosystem are largely unknown. By drilling into 3.5-million-year-old subseafloor basalt, we demonstrated the presence of methane- and sulfur-cycling microbes on the eastern flank of the Juan de Fuca Ridge. Depth horizons with functional...
The Eshamy suite plutons (ESP) are in the midst of the Sanak-Baranof (SB) belt, a series of neartrench, Paleocene to Eocene granitic intrusions into the Chugach-Prince William (CPW) terrane flysch along the southern margin of Alaska (Fig.1, Garver and Davidson, this volume and references therein). Intruded from 62-48 Ma, west-to-east migration of a subducting north-south-striking mid-ocean ridg...
Bulk-rock major and trace element geochemistry of a range of eclogite, garnet blueschist and garnet amphibolite rocks from northern New Caledonia has been determined in order to geochemically characterise subducted oceanic crust. The rocks experienced peak metamorphic conditions of 1.9 GPa and 600 jC and represent excellent samples of oceanic crust that was subducted to depths of approximately ...
This paper provides a summary of postcruise scientific results from Ocean Drilling Program (ODP) Leg 209 available to date, building upon shipboard observations and syntheses summarized in the Leg 209 Initial Results volume. During Leg 209, 19 holes were drilled at 8 sites along the Mid-Atlantic Ridge from 14°43′ to 15°44′N, mainly in residual mantle peridotite intruded by gabbroic rocks, in or...
Pillow lavas are one of the important rock units of Nain ophiolite. Rock forming minerals of Nain ophiolite pillow lavas are chloritized olivine, plagioclase, clinopyroxene (augite), Cr-spinel, magnetite, amphibole, chlorite, pumpellyite, epidote, prehnite and calcite. Whole rock geochemical analyses and composition of clinopyroxenes and chromian spinels of these rocks indicate that they are si...
Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/(3)He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/(3)He ratios of h...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید