magdy el-hedeny | King Saud University (original) (raw)
Papers by magdy el-hedeny
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen
Neues Jahrbuch für Geologie und Paläontologie - Monatshefte, 1998
Minerals, Mar 10, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Neues Jahrbuch für Geologie und Paläontologie, Dec 19, 2023
Proceedings of the Geologists' Association
Facies, Apr 1, 2023
The palaeoenvironments of the upper Palaeozoic succession in the eastern foot slopes of the North... more The palaeoenvironments of the upper Palaeozoic succession in the eastern foot slopes of the Northern Galala Plateau, west of the Gulf of Suez, Egypt, are interpreted based on a detailed study of the sequence-stratigraphic framework, sedimentary facies and trace fossils. The upper Carboniferous-lower Permian Aheimer Formation has been studied in its type section exposed in Wadi Aheimer. Three unconformities bound four 3rd-order depositional sequences, including the upper Carboniferous DS NG 1, and the lower Permian DS NG 2-4. These sequences are correlated with their counterparts on the North African and Arabian plates. The sedimentary facies characteristics indicate palaeoenvironments ranging from fluvial, estuarine, intertidal, shallow subtidal, shoreface to offshore transitional settings. The abundant and diverse ichno-assemblages are composed of horizontal, vertical and sub-vertical traces. At least 26 ichnotaxa have been identified, representing suites of the Glossifungites, proximal Cruziana, and proximal-archetypal Cruziana ichnofacies. Ichnofabric analysis revealed three distinct ichnofabrics: Tisoa, Schaubcylindrichnus and Zoophycos ichnofabrics. The trace and body fossil distribution and trophic structure of some of the recorded faunal assemblages confirm relatively stable and low-stress shallow-marine environments. In contrast, the trophic structure of some other assemblages indicates the influence of particular environmental parameters, including substrate consistency, bathymetry, water energy, productivity, rate of sedimentation, salinity and oxygen availability. The integrated results indicate that the sequences were formed during an interval dominated by different perturbations that resulted in a wide spectrum of depositional features. Moreover, evidence for Carboniferous-Permian glaciation is tentatively established in North Egypt but require further investigations.
Annales Societatis Geologorum Poloniae
Cretaceous Research, 2021
Abstract The palaeoecology and palaeoenvironments of the Cenomanian–lower Turonian succession in ... more Abstract The palaeoecology and palaeoenvironments of the Cenomanian–lower Turonian succession in the northern Eastern Desert of Egypt are interpreted, based on a detailed study of macrofaunal assemblages and sedimentary facies. The abundant molluscs and echinoids of the mixed carbonate-siliciclastic Galala and Abu Qada formations have been studied in three sections with ammonites that provide a well-correlated stratigraphical framework. Three unconformities (two Cenomanian sequence boundaries and a first Turonian one) bound two third-order depositional sequences. Facies development shows a strong relationship to the sequence architecture recognised. In addition, the facies characteristics indicate depositional palaeoenvironments ranging from lagoonal to deep subtidal settings on a homoclinal carbonate ramp that was proximally influenced by clastic input. The macrobenthic taxa identified in 51 samples, collected from the sections studied, are grouped into seven assemblages (A–G) that are described and interpreted as remnants of communities. The faunal distribution and trophic structure of most of the assemblages recorded confirm fully oxygenated and euhaline shallow-marine environments with mesotrophic productivity level, i.e., relatively stable and low-stress conditions. The trophic structure of some other assemblages, in contrast, reflects the influence of particular environmental parameters, dissolution of aragonitic shells and/or sample size effects. Environmental parameters controlling the faunal distribution include substrate consistency, bathymetry, water energy, surface-water productivity, rate of sedimentation and oxygen availability. The integrated litho- and biofacies results certify that the sequences were deposited during an interval dominated by different perturbations that resulted in a wide spectrum of depositional features and significant palaeoecological variations.
Ichnos, 2020
Disconnected aggregates of allochthonous fossil Nypa fruits occur in the Ammonite Hill Member of ... more Disconnected aggregates of allochthonous fossil Nypa fruits occur in the Ammonite Hill Member of the Dakhla Formation (Maastrichtian), exposed at the Bir Abu Minqar section, south Western Desert of Egypt. In a pale brown, calcareous siltstone and/or fine-grained sandstone layer, the fossil fruits found are densely infested by the borings Teredolites clavatus and Apectoichnus longissimus. In the specimens described, wood borings assigned to A. longissimus are more abundant than T. clavatus. Remains of the boring bivalves are not preserved. These aggregates of bored fruits likely accumulated in a warm, shallow, welloxygenated marine environment. Prior to final accumulation, Nypa fruits drifted in seawater only for a short time and exhibit evidence of biostratinomic alterations. The present study is the first to systematically describe the occurrence of both nominal ichnotaxa from the Maastrichtian rocks in Egypt.
Proceedings of the Geologists' Association, 2019
Here we describe the composition and distribution of sclerobionts on the late Eocene bivalve Caro... more Here we describe the composition and distribution of sclerobionts on the late Eocene bivalve Carolia placunoides and provide information about its paleoecology. More than 250 shells were collected from the Temple Member of the Qasr El-Sagha Formation exposed in El-Fayum Province. Nine ichnogenera have been recorded including Gastrochaenolites, Maeandropolydora, Caulostrepsis, Entobia, Centrichnus, Belichnus, Anellusichnus, Oichnus and Trypanites. The dense population of borings made by boring bivalves, Gastrochaenolites, is the most remarkable. Encrusters include serpulid worms (Spirobranchus cf. luxata), balanoid barnacles, and oysters. Shells of juvenile Carolia were the most dominant encrusters. Sclerobionts occurred on left and right valves; they apparently favoured the interior surfaces on both valves but they preferred no special sites. The Carolia placunoides shell concentration is interpreted as para-autochthonous assemblage.
Proceedings of the Geologists' Association, 2018
The ichnogenus Arachnostega Bertling, 1992 is recorded for the first time from a bioeroded, coral... more The ichnogenus Arachnostega Bertling, 1992 is recorded for the first time from a bioeroded, coral-rich, Middle Miocene limestone bed in the middle Siwa Escarpment Member (Marmarica Formation) at Siwa Oasis, northern Western Desert of Egypt. These burrowing traces are preserved on the surface of a few internal moulds of bivalves and gastropods. Until now, the ichnogenus Arachnostega included a single ichnospecies, A. gastrochaenae Bertling, 1992. In the material studied herein, two ichnospecies are identified, described, illustrated and compared with other, similar traces. One of these is a new ichnospecies of Arachnostega; this is here named A. siwaensis ichnosp. nov. It is distinguished from A. gastrochaenae in the possession of tunnels that usually branch in a V-pattern; intervals of ramification are longest in the main branch and decrease in second-and third-order branches. Arachnostega traces were produced in a warm, low-energy, shallow-marine (<10 m water depth) environment. Polychaetes are the most likely producers of marine Arachnostega, which are commonly occurred in the same studied bed. This new occurrence is significant in extending the known stratigraphical and geographical ranges of Arachnostega into the Middle Miocene of Egypt.
Proceedings of the Geologists' Association, 2017
Four Middle-Upper Jurassic sections from central Saudi Arabia have been investigated to evaluate ... more Four Middle-Upper Jurassic sections from central Saudi Arabia have been investigated to evaluate microfacies types and macro-invertebrate paleocommunities and to interpret their paleoecology and paleoenvironments. The studied Jurassic successions are part of the Middle-Upper Callovian Tuwaiq Mountain Limestone and the Middle-Upper Oxfordian Hanifa Formation. Three main facies were recorded, including mud-supported microfacies, grain-supported microfacies and boundstones. A data matrix comprising 48 macrobenthic species in 35 samples collected from four sections were grouped into fifteen assemblages and one poorly fossiliferous interval by means of a Q-mode cluster analysis. The recorded macrofaunal assemblages have been subdivided into low-stress and high-stress on the basis of hydrodynamic conditions, substrate type, nutrient supply and hypoxia. The low-stress assemblages occur in (a) high-energy paleoenvironments with firm substrates; (b) high-energy shoals with unstable substrates of low cohesion and in (c) low-energy open marine environments with soft-substrates. The moderate-to high-stress assemblages occur in (a) oligotrophic environments with reduced terrigenous input in shelf lagoonal or in restricted inner ramp settings; (b) low-energy, soft substrate environments with hypoxia below the sediment-water interface; and, in (c) high-energy shoals and shelf lagoonal environments. The temporal distribution patterns of epifaunal and infaunal bivalve taxa are controlled by variations in water energy, substrate characteristics and productivity level. The reported litho-and biofacies confirmed that the Callovian Tuwaiq Mountain Limestone and the Oxfordian Hanifa Formation were deposited across wide spectrum of depositional environments, ranging from restricted lagoon to moderately deeper open marine basin, and providing the perfect conditions for macrofossils.
Journal of African Earth Sciences, 2017
Two hundred and seventy eight specimens of fossil bivalves were collected from the Tuwaiq Mountai... more Two hundred and seventy eight specimens of fossil bivalves were collected from the Tuwaiq Mountain Limestone (Callovian) and the Hanifa Formation (Oxfordian), Central South Arabia. Of all the outcrops studied, the Khashm al Qaddiyah contains the richest assemblage of the bivalves (49 %), as regards variety and frequency; followed by Dirab (27 %), Jabal al Abakkayn (13 %) and Maáshabah (11 %). Twenty bivalve species have been identified and systematically described. They belong to fourteen genera, twelve families and nine orders. Among these species, six Callovian species; Grammatodon (Cosmetodon) elongatum (J.
Research Journal of …, 2011
Contaminations of persistent organic pollutants (POPs) such as, dichlorodiphenyl trichloroethane ... more Contaminations of persistent organic pollutants (POPs) such as, dichlorodiphenyl trichloroethane (DDT), hexachlorocyclohexane (HCH) and chlordane (CHLs) were examined in the edible mantle tissues of the commercial cuttlefish Sepia pharaonis Ehrenberg 1831, collected from the marine water of the Arabian Gulf. The mean concentrations of DDT, CHLs and HCH were in the ranges of 29.4-56 ng/g, 47.4-100 ng/g and 1-4 ng/g, respectively. Among the POPs analyzed, HCH showed the lowest concentrations ranging between 1 to 5 ng/g lipid wt. However, concentrations of DDT, CHLs and HCH, detected in this study, were generally comparable or lower than those found in studies of similar cephalopod species from other areas subject to a high anthropogenic impact. Relationships between total body lengths and/or dorsal mantle lengths of the organisms and the concentration values of the studied POPs were also considered. Compared with recommendations of the international organizations, there are no potential risks associated with consuming the studied cuttlefish species.
Proceedings of the Geologists' Association, 2017
At Siwa Oasis, the carbonate-rich Middle Miocene Marmarica Formation includes several firmground ... more At Siwa Oasis, the carbonate-rich Middle Miocene Marmarica Formation includes several firmground discontinuity surfaces, characterized by extensive burrow systems. These surfaces are confined to the boundary between the Oasis and Siwa Escarpment members in addition to several intraformational marine firmground discontinuities at several horizons within these two members. The marine trace fossils from all these discontinuities are represented mainly by the ichnogenus Thalassinoides. In all occurrences, Thalassinoides are characterized by a sharp erosional lower contact and grades upward into fossiliferous argillaceous limestone facies. Three Thalassinoides ichnospecies have been reported, including: Th. horizontalis Myrow, 1995, Th. suevicus (Rieth, 1932) and Th. paradoxicus (Woodward, 1830). They are mostly recorded as hypichnial/endichnial forms at the sole of fossiliferous argillaceous limestone facies. Rare exichnial occurrences are also recorded. Thalassinoides ichnospecies displayed considerable variations in their stratigraphic distribution, in addition to remarkable variations in their complexity and dimension. These variations are mostly reflecting environmental conditions prevailed during the trace-maker life. Paleoenvironmental interpretation of these burrows confirmed a welloxygenated shallow marine environment with extremely slow or nearly nil rate of sedimentation.
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen
Neues Jahrbuch für Geologie und Paläontologie - Monatshefte, 1998
Minerals, Mar 10, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Neues Jahrbuch für Geologie und Paläontologie, Dec 19, 2023
Proceedings of the Geologists' Association
Facies, Apr 1, 2023
The palaeoenvironments of the upper Palaeozoic succession in the eastern foot slopes of the North... more The palaeoenvironments of the upper Palaeozoic succession in the eastern foot slopes of the Northern Galala Plateau, west of the Gulf of Suez, Egypt, are interpreted based on a detailed study of the sequence-stratigraphic framework, sedimentary facies and trace fossils. The upper Carboniferous-lower Permian Aheimer Formation has been studied in its type section exposed in Wadi Aheimer. Three unconformities bound four 3rd-order depositional sequences, including the upper Carboniferous DS NG 1, and the lower Permian DS NG 2-4. These sequences are correlated with their counterparts on the North African and Arabian plates. The sedimentary facies characteristics indicate palaeoenvironments ranging from fluvial, estuarine, intertidal, shallow subtidal, shoreface to offshore transitional settings. The abundant and diverse ichno-assemblages are composed of horizontal, vertical and sub-vertical traces. At least 26 ichnotaxa have been identified, representing suites of the Glossifungites, proximal Cruziana, and proximal-archetypal Cruziana ichnofacies. Ichnofabric analysis revealed three distinct ichnofabrics: Tisoa, Schaubcylindrichnus and Zoophycos ichnofabrics. The trace and body fossil distribution and trophic structure of some of the recorded faunal assemblages confirm relatively stable and low-stress shallow-marine environments. In contrast, the trophic structure of some other assemblages indicates the influence of particular environmental parameters, including substrate consistency, bathymetry, water energy, productivity, rate of sedimentation, salinity and oxygen availability. The integrated results indicate that the sequences were formed during an interval dominated by different perturbations that resulted in a wide spectrum of depositional features. Moreover, evidence for Carboniferous-Permian glaciation is tentatively established in North Egypt but require further investigations.
Annales Societatis Geologorum Poloniae
Cretaceous Research, 2021
Abstract The palaeoecology and palaeoenvironments of the Cenomanian–lower Turonian succession in ... more Abstract The palaeoecology and palaeoenvironments of the Cenomanian–lower Turonian succession in the northern Eastern Desert of Egypt are interpreted, based on a detailed study of macrofaunal assemblages and sedimentary facies. The abundant molluscs and echinoids of the mixed carbonate-siliciclastic Galala and Abu Qada formations have been studied in three sections with ammonites that provide a well-correlated stratigraphical framework. Three unconformities (two Cenomanian sequence boundaries and a first Turonian one) bound two third-order depositional sequences. Facies development shows a strong relationship to the sequence architecture recognised. In addition, the facies characteristics indicate depositional palaeoenvironments ranging from lagoonal to deep subtidal settings on a homoclinal carbonate ramp that was proximally influenced by clastic input. The macrobenthic taxa identified in 51 samples, collected from the sections studied, are grouped into seven assemblages (A–G) that are described and interpreted as remnants of communities. The faunal distribution and trophic structure of most of the assemblages recorded confirm fully oxygenated and euhaline shallow-marine environments with mesotrophic productivity level, i.e., relatively stable and low-stress conditions. The trophic structure of some other assemblages, in contrast, reflects the influence of particular environmental parameters, dissolution of aragonitic shells and/or sample size effects. Environmental parameters controlling the faunal distribution include substrate consistency, bathymetry, water energy, surface-water productivity, rate of sedimentation and oxygen availability. The integrated litho- and biofacies results certify that the sequences were deposited during an interval dominated by different perturbations that resulted in a wide spectrum of depositional features and significant palaeoecological variations.
Ichnos, 2020
Disconnected aggregates of allochthonous fossil Nypa fruits occur in the Ammonite Hill Member of ... more Disconnected aggregates of allochthonous fossil Nypa fruits occur in the Ammonite Hill Member of the Dakhla Formation (Maastrichtian), exposed at the Bir Abu Minqar section, south Western Desert of Egypt. In a pale brown, calcareous siltstone and/or fine-grained sandstone layer, the fossil fruits found are densely infested by the borings Teredolites clavatus and Apectoichnus longissimus. In the specimens described, wood borings assigned to A. longissimus are more abundant than T. clavatus. Remains of the boring bivalves are not preserved. These aggregates of bored fruits likely accumulated in a warm, shallow, welloxygenated marine environment. Prior to final accumulation, Nypa fruits drifted in seawater only for a short time and exhibit evidence of biostratinomic alterations. The present study is the first to systematically describe the occurrence of both nominal ichnotaxa from the Maastrichtian rocks in Egypt.
Proceedings of the Geologists' Association, 2019
Here we describe the composition and distribution of sclerobionts on the late Eocene bivalve Caro... more Here we describe the composition and distribution of sclerobionts on the late Eocene bivalve Carolia placunoides and provide information about its paleoecology. More than 250 shells were collected from the Temple Member of the Qasr El-Sagha Formation exposed in El-Fayum Province. Nine ichnogenera have been recorded including Gastrochaenolites, Maeandropolydora, Caulostrepsis, Entobia, Centrichnus, Belichnus, Anellusichnus, Oichnus and Trypanites. The dense population of borings made by boring bivalves, Gastrochaenolites, is the most remarkable. Encrusters include serpulid worms (Spirobranchus cf. luxata), balanoid barnacles, and oysters. Shells of juvenile Carolia were the most dominant encrusters. Sclerobionts occurred on left and right valves; they apparently favoured the interior surfaces on both valves but they preferred no special sites. The Carolia placunoides shell concentration is interpreted as para-autochthonous assemblage.
Proceedings of the Geologists' Association, 2018
The ichnogenus Arachnostega Bertling, 1992 is recorded for the first time from a bioeroded, coral... more The ichnogenus Arachnostega Bertling, 1992 is recorded for the first time from a bioeroded, coral-rich, Middle Miocene limestone bed in the middle Siwa Escarpment Member (Marmarica Formation) at Siwa Oasis, northern Western Desert of Egypt. These burrowing traces are preserved on the surface of a few internal moulds of bivalves and gastropods. Until now, the ichnogenus Arachnostega included a single ichnospecies, A. gastrochaenae Bertling, 1992. In the material studied herein, two ichnospecies are identified, described, illustrated and compared with other, similar traces. One of these is a new ichnospecies of Arachnostega; this is here named A. siwaensis ichnosp. nov. It is distinguished from A. gastrochaenae in the possession of tunnels that usually branch in a V-pattern; intervals of ramification are longest in the main branch and decrease in second-and third-order branches. Arachnostega traces were produced in a warm, low-energy, shallow-marine (<10 m water depth) environment. Polychaetes are the most likely producers of marine Arachnostega, which are commonly occurred in the same studied bed. This new occurrence is significant in extending the known stratigraphical and geographical ranges of Arachnostega into the Middle Miocene of Egypt.
Proceedings of the Geologists' Association, 2017
Four Middle-Upper Jurassic sections from central Saudi Arabia have been investigated to evaluate ... more Four Middle-Upper Jurassic sections from central Saudi Arabia have been investigated to evaluate microfacies types and macro-invertebrate paleocommunities and to interpret their paleoecology and paleoenvironments. The studied Jurassic successions are part of the Middle-Upper Callovian Tuwaiq Mountain Limestone and the Middle-Upper Oxfordian Hanifa Formation. Three main facies were recorded, including mud-supported microfacies, grain-supported microfacies and boundstones. A data matrix comprising 48 macrobenthic species in 35 samples collected from four sections were grouped into fifteen assemblages and one poorly fossiliferous interval by means of a Q-mode cluster analysis. The recorded macrofaunal assemblages have been subdivided into low-stress and high-stress on the basis of hydrodynamic conditions, substrate type, nutrient supply and hypoxia. The low-stress assemblages occur in (a) high-energy paleoenvironments with firm substrates; (b) high-energy shoals with unstable substrates of low cohesion and in (c) low-energy open marine environments with soft-substrates. The moderate-to high-stress assemblages occur in (a) oligotrophic environments with reduced terrigenous input in shelf lagoonal or in restricted inner ramp settings; (b) low-energy, soft substrate environments with hypoxia below the sediment-water interface; and, in (c) high-energy shoals and shelf lagoonal environments. The temporal distribution patterns of epifaunal and infaunal bivalve taxa are controlled by variations in water energy, substrate characteristics and productivity level. The reported litho-and biofacies confirmed that the Callovian Tuwaiq Mountain Limestone and the Oxfordian Hanifa Formation were deposited across wide spectrum of depositional environments, ranging from restricted lagoon to moderately deeper open marine basin, and providing the perfect conditions for macrofossils.
Journal of African Earth Sciences, 2017
Two hundred and seventy eight specimens of fossil bivalves were collected from the Tuwaiq Mountai... more Two hundred and seventy eight specimens of fossil bivalves were collected from the Tuwaiq Mountain Limestone (Callovian) and the Hanifa Formation (Oxfordian), Central South Arabia. Of all the outcrops studied, the Khashm al Qaddiyah contains the richest assemblage of the bivalves (49 %), as regards variety and frequency; followed by Dirab (27 %), Jabal al Abakkayn (13 %) and Maáshabah (11 %). Twenty bivalve species have been identified and systematically described. They belong to fourteen genera, twelve families and nine orders. Among these species, six Callovian species; Grammatodon (Cosmetodon) elongatum (J.
Research Journal of …, 2011
Contaminations of persistent organic pollutants (POPs) such as, dichlorodiphenyl trichloroethane ... more Contaminations of persistent organic pollutants (POPs) such as, dichlorodiphenyl trichloroethane (DDT), hexachlorocyclohexane (HCH) and chlordane (CHLs) were examined in the edible mantle tissues of the commercial cuttlefish Sepia pharaonis Ehrenberg 1831, collected from the marine water of the Arabian Gulf. The mean concentrations of DDT, CHLs and HCH were in the ranges of 29.4-56 ng/g, 47.4-100 ng/g and 1-4 ng/g, respectively. Among the POPs analyzed, HCH showed the lowest concentrations ranging between 1 to 5 ng/g lipid wt. However, concentrations of DDT, CHLs and HCH, detected in this study, were generally comparable or lower than those found in studies of similar cephalopod species from other areas subject to a high anthropogenic impact. Relationships between total body lengths and/or dorsal mantle lengths of the organisms and the concentration values of the studied POPs were also considered. Compared with recommendations of the international organizations, there are no potential risks associated with consuming the studied cuttlefish species.
Proceedings of the Geologists' Association, 2017
At Siwa Oasis, the carbonate-rich Middle Miocene Marmarica Formation includes several firmground ... more At Siwa Oasis, the carbonate-rich Middle Miocene Marmarica Formation includes several firmground discontinuity surfaces, characterized by extensive burrow systems. These surfaces are confined to the boundary between the Oasis and Siwa Escarpment members in addition to several intraformational marine firmground discontinuities at several horizons within these two members. The marine trace fossils from all these discontinuities are represented mainly by the ichnogenus Thalassinoides. In all occurrences, Thalassinoides are characterized by a sharp erosional lower contact and grades upward into fossiliferous argillaceous limestone facies. Three Thalassinoides ichnospecies have been reported, including: Th. horizontalis Myrow, 1995, Th. suevicus (Rieth, 1932) and Th. paradoxicus (Woodward, 1830). They are mostly recorded as hypichnial/endichnial forms at the sole of fossiliferous argillaceous limestone facies. Rare exichnial occurrences are also recorded. Thalassinoides ichnospecies displayed considerable variations in their stratigraphic distribution, in addition to remarkable variations in their complexity and dimension. These variations are mostly reflecting environmental conditions prevailed during the trace-maker life. Paleoenvironmental interpretation of these burrows confirmed a welloxygenated shallow marine environment with extremely slow or nearly nil rate of sedimentation.