Tectonically driven carbonate ramp evolution at the southern Tethyan shelf: the Lower Eocene succession of the Galala Mountains, Egypt

Abstract

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.

Circum-Tethyan carbonate platform evolution during the Palaeogene: the Prebetic platform as a test for climatically controlled facies shifts

“…We recorded a new section of Ascoy in the SW part of the Prebetic platform and the classical sections of Oneil, Ibi, and Relleu for microfacies and biotic assemblages, comparable to the detailed microfacies analysis by Hoentzsch et al (2011a). In this study, we only present the results of the microfacies and focus on a reinterpretation and comparison with other studies in order to achieve a (2000), Sissingh (2000, 2003), and Thomas et al (2010).…”

“…11) Egypt (20°N) Carbonate platform successions in Egypt are dominated by larger benthic foraminifera limestones from the Early Eocene (Schuster 1996a(Schuster , 1996bWielandt 1996;Hoentzsch et al 2011aHoentzsch et al , 2011b. Rare isolated coral fragments from the Early Eocene are found in the Eastern Desert (Galala platform; Hoentzsch et al 2011aHoentzsch et al , 2011b and from the latest Lutetian in the Western Desert, whereas nummulitic limestones prevailed throughout the Eocene (Tawadros 2001).…”

“…Rare isolated coral fragments from the Early Eocene are found in the Eastern Desert (Galala platform; Hoentzsch et al 2011aHoentzsch et al , 2011b and from the latest Lutetian in the Western Desert, whereas nummulitic limestones prevailed throughout the Eocene (Tawadros 2001). During the Oligocene, major carbonate platforms of the Egyptian shelf were subaerially exposed and destroyed.…”

“…In this study we link and compare the data of 10 circum-Tethyan carbonate platforms with the succession of the South Iberian margin to achieve new information regarding timing and biotic impact of the Early Palaeogene greenhouse to Late Palaeogene icehouse transition. We conducted a high resolution microfacies analysis comparable to the study of Hoentzsch et al (2011a) of proximal and distal mass flow deposits, as well as creating a new carbon isotope record of these deposits. These results will reveal the impact of long-and short-term climatic evolution to shallow marine benthic assemblages, especially to larger benthic foraminifera and corals.…”

The Triassic platform of the Gador-Turon unit (Alpujarride complex, Betic Cordillera, southeast Spain): climate versus tectonic factors controlling platform architecture

“…Particularly, the evolution of tectonically controlled carbonate platforms has been widely described throughout the Phanerozoic (e.g., Wilson and D'Argenio 1982;Burchette 1988;Bechstädt and Boni 1989;Purdy et al 2003;Bosence 2005;Höntzsch et al 2010; among many others).…”