Open AccessPalaeomagnetism and Opaque Mineral Oxides of Some Basalt From West Central Sinai, Egypt
Author(s) -
Wassif Nadia A.
Publication year - 1991
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.1991.tb02514.x
Subject(s) - geology , basalt , sill , magnetite , paleomagnetism , mineral , geochemistry , volcanic rock , volcano , remanence , magnetic anomaly , wadi , mineralogy , magnetization , geophysics , paleontology , archaeology , geography , chemistry , physics , quantum mechanics , magnetic field , organic chemistry
SUMMARY A stable remanence was isolated from two intrusive occurrences of volcanic rocks collected from west central Sinai, Egypt. Tertiary basalts at Wadi Nukhul have a predominantly reverse magnetization with mean direction D = 173.5°, I =‐60.7° ( K = 46.6, α 95 = 8.2°, dyke and sill) and a palaeopole at 76°S, 193°E. Coarse primary magnetite (100–500 μm) with a Curie temperature between 540° and 580 °C is the principal magnetic mineral. A Mesozoic basaltic intrusion at Gebel Farsh El Azraq exhibits a predominantly normal magnetization carried mainly by fine‐grained (50–300 μm) titanomagnetite. Its mean direction is D = 139°, 7 = 44.6° ( K = 5.9, α 95 = 24.8°, N = 8 sites) with a palaeopole at 28.6°S and 179°E. These results, together with other results from west central Sinai have been compared with the apparent polar wander path (APWP) for Africa given by Irving & Irving (1982). the Mesozoic poles are not compatible with poles of similar age for Africa, reflecting a local effect of tectonic rotations and/or geomagnetic secular variation. In contrast, the Egyptian Early Tertiary poles compare favourably with the relevant part of the African APWP for the period later than 40 Myr, in good agreement with the K‐Ar ages of 22–25 Myr obtained for these intrusives.