[SCG56-02] Important role of the ultramafic layers in the lower oceanic crust and Moho
Keywords:ICDP Oman Drilling Project, D/V Chikyu, Ultramafic layer, Oceanic Crust, MohoTZ, Physical Properties
Whole-round data, including X-ray CT images, natural gamma radiation (NGR), gamma-ray attenuation (GRA) density, magnetic susceptibility (MS), P-wave velocity (Vp) and noncontact electrical resistivity were obtained. Split core color spectroscopy data were also collected. Magnetic susceptibility, P-wave velocity, bulk/grain density, porosity, and thermal conductivity were measured in discrete samples. Nearly 100% core recovery allowed us to take a large data set of petrophysical data on the cores from Oman ophiolite including fault zones and highly altered intervals.
Ultramafic rocks in the lower crustal section and MohoTZ show significantly higher porosity, electrical conductivity, magnetic susceptibility and thermal conductivity than gabbros. The electrical and magnetic properties of ultramafic layers also show clear correlations with the bulk density and porosity. Significant differences of the physical properties within those lithologies suggest that the ultramafic layers in the lower crust and the MohoTZ are key to understanding the seafloor structure.