STRUCTURAL SETTING AND TECTONIC EVOLUTION OF THE NORTHERN HAMMAM-FARAUN BLOCK (WADI-WASIT-WADI-WARDAN AREA), EASTERN SIDE OF THE SUEZ RIFT

The Wadi Wasit-Wadi Wardan area (the northern part of the Hammam Farau n Block) lies on the eastern side of the Suez rift between oppositely- tilted half grabens. Detailed field mapping of the block indicates tha t the pre-rift and syn-rift rocks are deformed by N- to WNW-oriented n ormal faults and subordinate folds related mainly to the movement on n earby faults. The block can be divided structurally into three NNW-ori ented sub-blocks, the middle one of which is a large graben, whereas t he eastern one defines a rollover on the downthrown side of the listri c rift-bounding fault. Seven deformations affected the Hammam Faraun B lock, the earliest of which (D1, Early Eocene) was associated with pre -rift ''Syrian arc'' folding. Oligocene deformation (D2) affected the southernmost part of the block and is probably related to the local up lift at the late stages of ''Syrian arc'' deformation. Early opening i n the Suez rift (D3) was associated with basaltic volcanicity conforma ble with the underlying pre-rift rocks. Deformations D4 through D6 are directly related to continued opening and evolution of this rift. The D4 event is related to the change from slow to rapid subsidence. A mi d-rift (Mid-clysmic) event (D5) led to structural reorganization of th e rift associated with uplift of the rift shoulder and deposition of f an conglomerates at the footslopes of fault scarps. Mild, late rift fa ulting marks the D6 event. Quaternary movements of a local nature (D7) formed minor normal faults and are probably related to local, non-tec tonic readjustment above subsurface faults. The tectonic events of the Hammam Faraun Block indicate the transition from ''Syrian are'' foldi ng (related to the convergence between Africa and Eurasia due to the c losure of the Neotethys) to the early stages of crustal separation bet ween Africa and Arabia (leading to the opening of the Suez and ancestr al Red Sea rifts). The onset of rifting is marked by a phase of Early Miocene volcanicity. Rift tilting followed this volcanicity and is rel ated to the displacement on the listric normal faults at the rift boun dary. Half grabens of the rift are marked by major, conjugate, steeply dipping breakaway faults at both sides. A listric fault marks one sid e and a planar fault marks the other side of each half graben. The nor thern part of the Hammam Faraun Block lies in the transfer zone betwee n the northern and central half grabens of the Suez rift. It has a bro ad anticlinal structure being a ''twist zone'' or an overlapping conve rgent conjugate transfer zone between the listric normal faults of the se two half grabens.