Figure 1. Location map with studied sections projected on line perpendicular to direction of platform progradation. Contours indicate elevations of Galala Mountains. ABSTRACTThe larger-foraminifera turnover (LFT) during the Paleocene-Eocene transition constitutes an important step in Paleogene larger-foraminifera evolution, involving a rapid increase in species diversity, shell size, and adult dimorphism. A platform-to-basin transect in Egypt provides new data on timing and causal mechanisms through correlation with planktic biozonations and through integration with regional paleoenvironmental data. The LFT coincides with the boundary between shallow benthic biozones SBZ4 and SBZ5 and closely correlates with the Paleocene-Eocene Thermal Maximum (PETM). Enhanced oligotrophy from the late Paleocene onward favored the diversification of K-strategist larger foraminifera. We suggest that a short-term eutrophication during the PETM led to a temporary decline of extreme K-strategist larger-foraminifera species, providing opportunities for new taxa with different ecological strategies to develop. During post-PETM oligotrophic conditions, these new taxa were able to evolve rapidly and soon dominated early Eocene larger-foraminifera assemblages, whereas many Paleocene taxa gradually disappeared. The success of larger foraminifera during the early Paleogene appears climatically controlled. Because of the vulnerability of corals to high surface-water temperatures, the late Paleocene to early Eocene global warming may have favored larger foraminifera at the expense of corals as the main carbonate-producing component on carbonate platforms at lower latitudes.

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The succession of the Galala Mountains at the southern Tethyan margin (Eastern Desert, Egypt) provides new data for the evolution of an isolated carbonate platform in the Early Eocene. Since the Late Cretaceous emergence of the Galala platform, its evolution has been controlled strongly by eustatic sea-level Xuctuations and the tectonic activity along the Syrian Arc-Fold-Belt. Previous studies introduced Wve platform stages to describe platform evolution from the Maastrichtian (stage A) to the latest Paleocene shift from a platform to ramp morphology (stage E). A Wrst Early Eocene stage F was tentatively introduced but not described in detail. In this study, we continue the work at the Galala platform, focussing on Early Eocene platform evolution, microfacies analysis and the distribution of larger benthic foraminifera on a south-dipping inner ramp to basin transect. We redeWne the tentative platform stage F and introduce two new platform stages (stage G and H) by means of the distribution of 13 facies types and syn-depositional tectonism. In the earliest Eocene (stage F, NP 9b-NP 11), facies patterns indicate mainly aggradation of the ramp system. The Wrst occurrence of isolated sandstone beds at the mid ramp reXects a post-Paleocene-Eocene thermal maximum (PETM) reactivation of a Cretaceous fault system, yielding to the tectonic uplift of Mesozoic and Palaeozoic siliciclastics. As a consequence, the Paleocene ramp with pure carbonate deposition shifted to a mixed carbonate-siliciclastic system during stage F. The subsequent platform stage G (NP 11-NP 14a) is characterised by a deepening trend at the mid ramp, resulting in the retrogradation of the platform. The increasing deposition of quartzrich sandstones at the mid ramp reXects the enhanced erosion of Mesozoic and Palaeozoic deposits. In contrast to the deepening trend at the mid ramp, the deposition of cyclic tidalites reXects a coeval shallowing and the temporarily subaerial exposure of inner ramp environments. This oppositional trend is related to the continuing uplift along the Syrian Arc-Fold-Belt in stage G. Platform stage H (NP 14a-?) demonstrates the termination of Syrian Arc uplift and the recovery from a mixed siliciclastic carbonate platform to pure carbonate deposition.

We present a comprehensive facies scheme for west-central Jordan platform deposits of upper Albian to Turonian age, discuss Cenomanian and Turonian carbonate cycles, and reconstruct the paleogeographic evolution of the platform. Comparisons with adjacent shelf areas (Israel, Sinai) emphasize local characteristics as well as the regional platform development. Platform deposits are subdivided into fifteen microfacies types that define eight environments of deposition of three facies belts. Main facies differences between Cenomanian and Turonian platforms are: rudist-bearing packstones that characterise the higher-energy shallow subtidal (transition zone) during the Cenomanian, and fossiliferous (commonly with diverse foraminifer assemblages) wackestones and packstones of an open shallow subtidal environment. On Turonian platforms high-energy environments are predominantly characterised by oolithic or bioclastic grainstones and packstones, whereas peritidal facies are indicated by dolomitic wackestones with thin, wavy (cryptmicrobial) lamination. Rhythmic facies changes define peritidal or subtidal shallowing-up carbonate cycles in several Cenomanian and Turonian platform intervals. Cyclicities are also analysed on the base of accommodation plots (Fischer Plots). High-frequency accommodation changes within lower Cenomanian cyclic bedded limestones of the central and southern area exhibit two major 'cyclic sets' (set I and II) each containing regionally comparable peaks. Accommodation patterns within cyclic set II coincide with the sequence boundary zone of CeJo1. The lateral and vertical facies distributions on the inner shelf allow the reconstruction of paleogeographic conditions during five time intervals (Interval A to E). An increased subsidence is assumed for the central study area, locally (area of Wadi Al Karak) persisting from middle Cenomanian to middle Turonian times. In contrast, inversion and the development of a paleo-high have been postulated for an adjacent area (Wadi Mujib) during late Cenomanian to early Turonian times, while small-scale sub-basins with an occasionally dysoxic facies developed northwards and further south during this time interval. A connection between these structural elements in Jordan with basins and uplift areas in Egypt and Israel during equivalent time intervals is assumed. This emphasises the mostly concordant development of that Levant Platform segment.

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