The Southwest Indian Ridge (SWIR) at 9^168E and 52^538S is characterized by ultra-slow, oblique spreading and contains one of the few documented occurrences of pyroxenite veins associated with abyssal peridotites. The origin of these uncommon lithologies is still debated.We present a detailed study (including electron microprobe and laser ablation inductively coupled plasma mass spectrometry) o...

To expand investigations into the phylogenetic diversity of microorganisms inhabiting the subseafloor biosphere, basalt-hosted crustal fluids were sampled from Circulation Obviation Retrofit Kits (CORKs) affixed to Holes 1025C and 1026B along the Juan de Fuca Ridge (JdFR) flank using a clean fluid pumping system. These boreholes penetrate the crustal aquifer of young ocean crust (1.24 and 3.51 ...

High He/He ratios found in ocean island basalts are the main evidence for the existence of an undegassed mantle reservoir. However, models of helium isotope evolution depend critically on the chemical behaviour of helium during mantle melting. It is generally assumed that helium is strongly enriched in mantle melts relative to uranium and thorium, yet estimates of helium partitioning in mantle ...

The cascade from tides to turbulence has been hypothesized to serve as a major energy pathway for ocean mixing. We investigated this cascade along the Hawaiian Ridge using observations and numerical models. A divergence of internal tidal energy flux observed at the ridge agrees with the predictions of internal tide models. Large internal tidal waves with peak-to-peak amplitudes of up to 300 met...

The Ontong Java and Manihiki oceanic plateaus are believed to have formed through high-degree melting of a mantle plume head. Boninite-like, low-Ti basement rocks at Manihiki, however, imply a more complex magma genesis compared with Ontong Java basement lavas that can be generated by ∼30% melting of a primitive mantle source. Here we show that the trace element and isotope compositions of low-...

Abstract We conducted the geochemical modeling of trace element contents for primary melts olivine-phyric rocks from Kamchatsky Mys. This reveals substantial chemical heterogeneity their source while average composition is close to enriched DMM (E-DMM). The estimation melting degree in range 9.1 ± 3.8% model modal batch 15.4 5.2% accumulated fractional melting, which slightly higher than primit...

Introduction: In understanding the evolution of the Moon, a number of its fundamental magmatic characteristics must be explained in the context of other geophysical and geological observations. Volcanic activity subsequent to the formation of anorthositic crust was dominated by the eruption of mare basalt. (1) The main phase of mare volcanism began ~500 Myr after the crystallization of the anor...

S U M M A R Y The active mid-ocean ridge of the Arctic Ocean, named Gakkel ridge, is the slowest spreading ridge of the global system of mid-oceanic ridges with full spreading rates declining from about 12.5 to 6 mm yr−1 from west to east. Geological models of seafloor spreading predict a decreasing intensity of magmatic processes with decreasing spreading rate. In summer 2001, the multidiscipl...

This paper reports the first discovery of basic igneous rocks in Bairin Right Banner southeastern Inner Mongolia, China. To understand genesis and tectonic evolution these rocks, we have carried out geochronology geochemistry research on them. The results show that LA-ICP-MS zircon U-Pb concordant mean ages massive basalt, diabase, pillow basalt are 272.0 ± 2.8 Ma, 261.5 3.2 256.5 2.5 respectiv...