Precambrian Research 123 (2003) 249–268 Geothermobarometric evidence for a metamorphic core complex in Sinai, Egypt P. Brooijmans a,∗ , B. Blasband a , S.H. White a , W.J. Visser a , P. Dirks b a Structural Geology, Geodynamics Research Institute, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands b Department of Geology, University of Zimbabwe, Mount Pleasant, Harare, Zimbabwe Received 4 April 2001; received in revised form 12 December 2001; accepted 12 December 2001 Abstract Blasband et al. [Geologie en Mijnbouw 76 (1997) 247, J. Geol. Soc. Lond. 157 (2000) 615] postulated a metamorphic core-complex model for the Wadi Kid area, south Sinai, Egypt. This core complex was formed in an extensional setting after gravitational collapse of the East African Orogen in the Late Proterozoic. Arc-accretion was responsible for the closure of the Mozambique Ocean. Blasband et al. [Geologie en Mijnbouw 76 (1997) 247, J. Geol. Soc. Lond. 157 (2000) 615] based their theory mainly on structural data. In order to justify this model geothermobarometric evidence is crucial. Therefore, the metamorphic rocks of the Wadi Kid area were the subject of a detailed metamorphic study. The M 1 metamorphic phase is characterized by greenschist-facies conditions and is related to arc-accretion. The M 2 metamor- phic phase is the main subject of this paper. The petrologic characteristics of pelitic and mafic rocks that were metamorphosed dur- ing M 2 show that the lower crustal rocks in the Wadi Kid area were subjected to upper greenschist to upper amphibolite conditions of the low-pressure/high-temperature type at the end of the Late Proterozoic. Garnet-biotite and amphibole-plagioclase geother- mometry reveal temperatures of 488–684 ◦ C. Plagioclase-biotite-muscovite-garnet geothermometry and amphibole-plagioclase geobarometry indicate pressures of 3.42–4.28 kbar. The M 2 metamorphic phase is associated with a D 2 deformation phase. This phase is a relict of gravitational collapse during the final stages of the collision of East and West Gondwanaland. © 2003 Elsevier Science B.V. All rights reserved. Keywords: Arabian-Nubian Shield; Wadi Kid area; Geothermobarometry; Late Proterozoic; Metamorphic core complexes 1. Introduction Blasband et al. (1997) were the first to acknowledge the presence of core complexes in the Arabian Nu- bian Shield, more specifically the Wadi Kid area (SE Sinai, Egypt). Structural studies in this area indicated the presence of a core complex as a result of exten- sional collapse during the Late Proterozoic (Blasband et al., 1997, 2000). Because core complexes display a ∗ Corresponding author. E-mail address: patrick.brooijmans@tip.nl (P. Brooijmans). typical metamorphic evolution, we believe that a de- tailed metamorphic study is necessary to demonstrate that the core-complex model is valid for the Wadi Kid area. Previous studies in the Wadi Kid area indicate that two metamorphic phases can be recognized (Shimron, 1980, 1984, 1987; Reymer, 1983, 1984; Reymer et al., 1984). Phase M 1 is characterized by greenschist-facies conditions (Shimron, 1987). Pres- sure and temperature conditions were estimated at 3–4 kbar and 300–400 ◦ C. The M 1 phase was believed to have been related to compression at upper crustal 0301-9268/03/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0301-9268(03)00071-8