Palaeomagnetism of some Miocene rocks, Qattara depression, western desert, Egypt

Eleven sites comprising 76 core samples of Lower (sandstone) and Middle (limestone) Miocene age were collected from the northeastern tip of the Qattara depression in the north of the Western Desert of Egypt. The majority of samples showed weak to very weak remanent magnetization with goethite, haematite and titanomagnetite as the main magnetic carriers. However, with a careful detailed thermal demagnetization, they yielded stable, probably primary, magnetization. The resultant overall mean direction of 2.9 degrees/32.2 degrees with alpha(95)=2.3 degrees corresponds to a palaeomagnetic pole position of 76.5 degrees N and 198.0 degrees E with A(95)=2.0 degrees, which seems to agree with other known African Miocene pots. This result implies that the Qattara area has been stable at least since Early Miocene. The presence of goethite as the main magnetic carrier supports the assumption that weathering has been playing an important role in the development and shaping of the depression. Copyright (C) 1996 Elsevier Science Ltd