The Bransfield Strait is the narrow, late Tertiary to Quaternary marginal basin separating the South Shetland Islands from the northern end of the Antarctic Peninsula magmatic arc. Quaternary volcanism in the strait is tholeiitic to mildly alkaline, and contrasts chemically with the pre-Quaternary calc-alkaline arc volcanism. Geochemical evidence presented here...
Volcanic rocks from hotspots and island arcs/backarcs typically have enriched trace
element and isotopic compositions that contain a contribution from subducted oceanic crust.
Isotopic and trace element data suggest that the enriched components in hotspot volcanism
are ancient subducted sediment and crust, and the enriched components in arc/backarc
volcanism are...
The interaction of basalt melt with mantle harzburgite at low pressure might result in silica enrichment of the melt by assimilation of orthopyroxene. Experimental tests of this hypothesis show that silica-rich liquids (56 wt %) are produced by melt-orthopyroxene reaction at 1200° to 1250°C. These silica-rich liquids are enriched in...
The subsurface microbial biosphere in the igneous oceanic crust has implications for global geochemical cycling, early life on Earth, and the search for life on Mars. Microscopic evidence of a subsurface microbial ecosystem includes biotic alteration textures associated with basaltic glass. The exact conditions in the basaltic layer that make...
Igneous oceanic crust encompasses ~60% of Earth’s surface and is composed of basalt glass and mafic, ultramafic, and felsic minerals. A vast marine aquifer lies within the crust, exchanging geochemically altered fluids with seawater from the overlying ocean at ridge crests, flanks, seamounts, and outcrops where permeable crust is exposed....
Oceanic crust covers nearly 70% of the Earth's surface, of which, the upper,
sediment layer is estimated to harbor substantial microbial biomass. Marine crust;
however, extends several kilometers beyond this surficial layer, and includes the
basalt and gabbro layers. In particular, the basalt layer has high permeabilities which
allows for...
We propose alternative mechanisms for the origin of three unusual rock suites, high-Mg andesites, NaTi basalts, and arclike rocks, that have been dredged from the Woodlark basin, southwest Pacific Ocean. We show that the high-Mg andesites and NaTi basalts are associated with an unusually cool ridge environment. The cooling is...