Study of Palaeomagnetism and Some Magnetic and Physical Properties of Some Tertiary Igneous Rocks between Sana’a and Al-Hudyadah Region (Republic of Yemen)

Palaeomagnetism and some magnetic and physical properties (magnetic susceptibility, intensity of the Natural Remnant Magnetization (NRM), ac current electrical conductivity and density) of 136 samples from 22 sites of the Yemen Volcanic Group TKY (Tertiary and (or) Cretaceous) from igneous rock exposures along the road from Sana’a – west towards Al-Hudyadah were studied. A single population consists of seven Virtual Geomagnetic Poles (VGP), of the Upper Oligocene, was accepted and a mean at 182.81° E, 77.44° N with α95= 12.5° was calculated. The different properties were measured in order to use these properties as characteristic factors to discriminate the neighboring igneous flows. The measurement of the in situ magnetic susceptibility of 140 points, distributed on 7 sub-areas, in the region helped to calculate the mean value of the magnetic susceptibility of each sub-area, which might be used in any magnetic interpretation of aeromagnetic or magnetic anomalies. Also, the density of 132 samples were measured and a mean value of the density of each sub-area was calculated in order to be used in any future interpretation of any gravity anomaly in the area.