Prior to eruption at mid-ocean ridges, melts must travel through >6 km of crust from their origin in the mantle. The final composition of the melts is dependent on both the melting conditions and magmatic processes within the crust. While mid-ocean ridge basalt (MORB) glasses are commonly used to infer...
In an attempt to understand the phase equilibria and petrogenesis of MORB anorthitic plagioclase, Cr-spinel commonly hosted within anorthitic plagioclase has been investigated petrographically and compositionally. Based on spinel-anorthite relationships from three samples of plagioclase ultra-phyric basalt (PUB; Southeast Indian Ridge, Axial Seamount and West Valley Segment, Juan de Fuca...
The Kane Oceanic Core Complex (OCC) is a valuable window into crustal architecture and chemical composition of the lithosphere beneath a slow-spreading ocean ridge. A suite of > 30 samples (comprised of whole rocks, mineral separates and basalt glasses) has been analyzed for ³He/⁴He isotope ratios and He concentrations. Gas...
The seismicity at the northern section of the Gorda Ridge has been
studied with Ocean Bottom Seismographs. Nearly one hundred earthquakes
were located with RMS travel time residuals less than 0.5 seconds.
Most of these events lie within or near the array and they are probably
associated with the dynamics...
We have determined the seismic crustal structure of the
northern part of the Gorda Ridge using signals generated by
explosive charges and recorded on Ocean Bottom Seismometers. The
shot pattern forms two parallel lines, one on the east flank and the
other along the median valley. Inversion of the travel...
Magmatic processes control the chemical compositions of all lavas erupted at
mid-ocean ridges. In this thesis, I present studies of magmatic processes on three
different mid-ocean ridges to determine which processes are in action and to what extent
each has affected the chemistry of mid-ocean ridge basalts at each location....
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...
