Changes of palaeozonation patterns within Miocene coral reefs, Gebel Abu Shaar, Gulf of Suez, Egypt

The Gebel Abu Shaar represents the southern end of a tilted fault-block con sisting of Precambrian basement upon which a mixed siliciclastic-carbonate platform developed during mid-Miocene time. The Miocene sequence contains c oral reefs and reef facies. Palaeozonation patterns of the Miocene coral re efs were assessed on the well-preserved outcrops of the Gebel Abu Shaar by recording both qualitative and quantitative data of reef-building assemblag es. The various patterns of palaeozonation were analysed and compared at di fferent spatial and temporal scales, including both within-reef and between -reef variations. The palaeozonal changes recorded within these fossil reef s are similar to those described from present-day living coral reefs and in volve contraction or extension, fusion or splitting, replacement and omissi on of reef-builder zones. Depending on the scale concerned, the nature and importance of changes affecting the palaeozonation pattern vary. Spatial va riations of the palaeozonal pattern appear mainly controlled by local chang es of ecological conditions while temporal variations are related to region al and global environmental changes.