Cenozoic and Mesozoic basalts from Egypt: a preliminary survey with a view to paleointensity

Abstract

Numerous phases of igneous activity took place in Egypt during the Mesozoic and the Cenozoic but no paleointensity results have ever been published from these rocks. Therefore a preliminary survey was conducted in the northern part of Egypt and in Sinai to test the suitability of these basalts for paleointensity determinations. Three Oligo-Miocene sites have been sampled north of Cairo: Abu Zaabal, Qatrani, and 6th of October City. In Sinai, we sampled Jurassic basalts in Wadi Budra and Oligo-Miocene rocks from Wadi Nukhul. The main magnetic carriers of these rocks are titanomagnetites with varying Ti content. Large secondary components are present in most middle Jurassic basalts and discrepancies remain in the directional analysis so this sill cannot be used for paleointensity experiments and the associated poles should not be considered for paleomagnetic reconstructions either. Directional analysis of the Oligo-Miocene basalts is very straightforward and updated mean VGPs have been calculated from the Cairo area (68.9• N, 91.3 • E; Kappa = 274; A 95 = 3.7) and from Wadi Nukhul (72.7 • N, 13.4• E; Kappa = 528; A 95 = 5.4). Pseudo-paleointensity results obtained as well from stable Egypt as from Sinai are promising, with values lower or similar (between 29 to 58 μT) to present-day field intensity.

Source-to-sink magnetic properties of NE Saharan dust in Eastern Mediterranean marine sediments: review and paleoenvironmental implications

“…Magnetite is ubiquitously present in a wide range of volcanic rocks ranging from Precambrian (Reischmann et al, 1992), to Paleozoic (Bachtadse and Briden, 1991), Mesozoic (Lotfy, 2011), and Cenozoic (Hussain and Aziz, 1983;Perrin et al, 2009) in age, and also in igneous, metamorphic, and sedimentary rocks that range in age from Proterozoic (Reischmann et al, 1992) to Paleozoic (Davies et al, 1980) and Mesozoic (Hussain and Aziz, 1983). Magnetite is also the dominant magnetic mineral in Paleogene (Lotfy and van der Voo, 2007), Neogene (Abdeldayem, 1996;Lean et al, 1998), and Quaternary (Lean et al, 1998) sedimentary rocks.…”

3D Gravity and magnetic inversion modelling for geothermal assessment and temperature modelling in the central eastern desert and Red Sea, Egypt

“…Volcanic activity has played a significant role in the geological history of the Eastern Desert. Mesozoic volcanic activity occurred during the Jurassic-Early Cretaceous period (155–125 Ma), while the Late Cretaceous-Early Tertiary periods (90–60 Ma) marked another phase of volcanic activity 25 . Subsequent volcanic events took place during the Cenozoic and Paleocene epochs, followed by widespread tertiary basaltic volcanism in the Eocene, associated with the opening of the Red Sea 25 .…”

Evolution of geothermal systems around the Red Sea

“…Red Sea rift related volcanism in Egypt is represented by Late Oligicene to Middle Miocene basaltic rocks in northern part of Sinai. Volcanic activity continued during the Quaternary period and is also represented by basaltic rocks in the south-western desert (Siedner 1973;Meneisy and Kreuzer 1974;Perrin et al 2009). …”