Chemical composition of glauconite and montmorillonite group minerals from sediments and rocks of the Norwegian Sea

Two quadrupole splitting doublets with delta E_q = 0.74 and 1.62 mm/s were found in the montmorillonite spectra. The more intense doublet corresponds to iron in a somewhat distorted tetrahedral coordination, while the less intense corresponds to quadri-coordinated iron. The EPR spectrum also exhibits two lines with a q-factor of 3 and 4.3, which corresponds to transformed minerals.

Vitrinite reflectance of ODP Leg 139 samples (Table 1)

Isolated kerogens from four sites in the Middle Valley hydrothermal region of the Juan de Fuca Ridge (Ocean Drilling Project (ODP) Leg 139) were analysed by electron paramagnetic resonance (EPR) spectroscopy. Measurements of peak width, spin density and power saturation for site 857 kerogens, which increased regularly in maturity downhole, show correlation with vitrinite reflectance values from 0.61 to 2.5%, indicating the start of the oil window at depths from 200 to 400 m. Spin density increases to 1.56 * 10**17 spins per gram and peak width decreases to 3.45 G (gauss) with increasing depth. The tendency to power saturate also decreases with increasing maturity and increasing vitrinite reflectance within the oil window. These trends are consistent with a model in which exchange processes are occurring and cause changes in the EPR behavior of samples from this site. Sediments from other Middle Valley sites, 855, 856 and 858 contain large quantities of pyrite with Mn2+ impurities which interact with the carbon radical to distort the EPR measurements.