الفهرس 
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Abstract
ABSTRACT
The Hammam Faraun block is the most important tectonic blocks of the central half graben of the Gulf of Suez. The study area represents the northern part of this block with the southern part of the Gharandal accommodation zone. The present study deals with the structural development of the rift related structures and its impact on the sediment distribution and facies variation around the study area.
The stratigraphic succession in the study area is a Carboniferous to Miocene Pre-rift section underlying Miocene to Recent Syn-rift and Post-rift deposits. The boundary between these two elements is marked by a major unconformity, in places associated with extrusive basalt and dyke intrusion. The Pre-rift is dominated by the Paleozoic sandstones, and is capped by transgressive Cretaceous carbonates and Paleogene shales and limestones. In the rift- and Post-rift section, the Oligocene is largely missing and Miocene sediments overly the Eocene carbonates. The later Miocene is developed as a thick sequence of evaporites and siliciclastics, which are truncated and overlain by Plio-Pleistocene sands and gravels.
Detailed field analysis and mapping of the Hammam Faraun district revealed certain deformations that have been honored by gravitational tectonic. Slump structures of complex folding and faulting are found restricted to certain stratigraphic intervals that are distributed in the Eocene and the Lower Miocene sequences. Wide varieties of deformation patterns, including complex folds, thrust and normal faults, rafts, diapirs, fisher-street, and liquefaction vents, are traced and measured in a purpose of strain-stress analysis. Gravitationally driven slumping deformations are essentially generated by shear mechanism, which was found accelerating in both directions of toe-front and the decollement surface. The shear-related structures are traced in complex patterns and frequent existence near the decollement surfaces and own intricated contractional features near the toe-front. Proceeding of glided slabs from the head of gliding (extensional strain), to the toe-front (compressional domain) have been resulted in overprinting of the extensional structures by superimposed contractional forms. Successive slumps are representing by very complex tectonic patterns. The Eocene sequences encompass demonstrative synsedimentary slump structures and olistostromes indicating Eocene tectonics. It can be concluded that the Eocene basin and intrabasinal ridges had been equated by Eocene tectonics that caused ridge uplifting, denudation and block-detachment. These charged the warped seabed basinal troughs and triggered gravitational tectonics and formation of olistostromes. Gravitational tectonics within the open marine Lower Miocene sediments are attributed to basin - slopes that created by rapid subsidence and downward movements along the bounding rift-related faults.
The northern part of the Hammam Faraun block is divided structurally into eight sub-blocks, each sub-block has characteristic structures and dip direction(s). These sub-blocks are: the Gabel Hammam Faraun-Gabel Thal, El Hagrah-El Ganobia, Wadi Thal, El Gushia, El Mreir-El Muntalaa, El Tayiba-Rod El Awad, Abu Ideimat-Musabaa Salama and Rift margin sub-blocks. Detailed field mapping of these sub-blocks indicate that the Pre-rift and Syn-rift rocks are highly deformed by faults and subordinated folds related mainly to the movements on nearby fault. These faults are mainly normal dip- slip and, in few cases, oblique-slip faults, in addition, there are two small-scale thrust faults. Faults oriented NW, NNW, NNE, ENE and WNW. Slickenlines indicate that the NW set are normal, or right-lateral or left-lateral, those of the NNW and NNE sets are normal and left-lateral, and those of the WNW set are right-lateral or normal or left-lateral. There are seven large-scale transfer zones, four of those are synthetic and the remaining three are an antithetic. Relay ramps, trap door faults, transfer faults, accommodation zones and twist zones are found in the area due to the interact of the large-scale faults.
Folding plays an important role in the deformation and their axes are oriented NW, NNE and NE. Most of these folds are plunging synclines and plunging anticlines whereas the synclines are usually longer than anticlines. The plunge angles for 42 folds were measured in the field and range from 10° to 30°. The length of mapped folds range from 0.1 to 11.6 km. In the most common geometry the fold axes lie parallel to or sub-parallel to the strike of nearby faults but another groups has fold axes lie perpendicular to the strike of the fault. Monoclines in the mapped area formed due to draping of bedding over normal faults.
Detailed structural analyses of the mapped area indicate that the study area has two main ridges trending in NNE and NE directions oblique to the direction of the Gulf of Suez rift. The first one, the Gabel Hammam Faraun-Gabel Thal sub-block, is structurally controlled. The olistostromes indicate the ridge was active during deposition of the Early-Middle Eocene Waseiyit Formation and uplifted after Eocene times. Because it is intruded by volcanicity, contains outcrops of the oldest rock units and some Miocene sediments are preserved in the overlapping areas. So, we can describe this ridge as intra-basin ridge, and it may be extend into the offshore area.
This ridge separates two large Miocene basins, which have the same direction as the Gulf of Suez rift. If a basin forms as a result of faulting then its direction should be similar to the trend of the faults. So, we can suggest that, these basins formed according to the geometry of the depositional surface after Eocene times and this geometry was fault controlled. There is additional evidence that fault controlled topography was prevalent at this time. Basaltic lava of Oligo-Miocene age fills a graben and faulted Tayiba Formation lies beneath the Early Miocene Nukhul Formation. The two basins were connected together in the northern part of the study area and the dip increases northwards as well. The major synclines that dominate the Miocene basins have the same trend as the rift.
The second ridge, the El Hagrah-El Ganobia sub-block, is structurally and topographically lower than the first one and capped by Quaternary terraces. The hanging wall of the northern boundary fault has several small-scale folds that trend almost perpendicular to the fault. These folds are related to displacement gradients on a segmented fault, which sets up fold trains within the fault walls but in these cases the hinges lie at high angles to the fault.
On the eastern side of the map the Miocene-bounding fault (F10) is exposed. Whereas Miocene sediments can be found in its hanging wall there are no Miocene sediments to the NE of this fault. This fault dips to the SW and extends to the NW until dies in a transfer zone where another fault (F15) is born which dips to the NE. All of the rocks that lie to the NE of the F10-fault dip to the NE as a result of drag on its surface and forming rollover anticline.
The rift shoulder fault (F14) lies in the southeastern portion of the study area in a crescentic shape. The displacement on the fault is larger to the south and decreases northwards. In the northeastern corner of the map there is no rift shoulder fault and the rocks are horizontally and dip to the west to form a large relay ramp. This dip can be observed in both the hanging wall and footwall of fault F15 and the Miocene sediments overlap the pre-rift rocks in footwall of F15-fault. This arrangement suggests that footwall uplift due to movements on F15-fault may have formed the northeastern limit of the Miocene sediments in the absence of the Miocene-bounding fault which ends at Wade Waseiyit. The absence of the Nukhul Formation in the southern part of the study areas suggests that during Miocene times the syn-depositional surface may have had a northward dip. This dip was imposed by fault-controlled uplift of the southeastern portion of the study area. A similar arrangement is indicated by the distribution of the Abu Alaqa Formation. Fan-glomerates that are derived from the denudation of the rift shoulder, this means large shoulder uplifting due south.
ABSTRACT
The Hammam Faraun block is the most important tectonic blocks of the central half graben of the Gulf of Suez. The study area represents the northern part of this block with the southern part of the Gharandal accommodation zone. The present study deals with the structural development of the rift related structures and its impact on the sediment distribution and facies variation around the study area.
The stratigraphic succession in the study area is a Carboniferous to Miocene Pre-rift section underlying Miocene to Recent Syn-rift and Post-rift deposits. The boundary between these two elements is marked by a major unconformity, in places associated with extrusive basalt and dyke intrusion. The Pre-rift is dominated by the Paleozoic sandstones, and is capped by transgressive Cretaceous carbonates and Paleogene shales and limestones. In the rift- and Post-rift section, the Oligocene is largely missing and Miocene sediments overly the Eocene carbonates. The later Miocene is developed as a thick sequence of evaporites and siliciclastics, which are truncated and overlain by Plio-Pleistocene sands and gravels.
Detailed field analysis and mapping of the Hammam Faraun district revealed certain deformations that have been honored by gravitational tectonic. Slump structures of complex folding and faulting are found restricted to certain stratigraphic intervals that are distributed in the Eocene and the Lower Miocene sequences. Wide varieties of deformation patterns, including complex folds, thrust and normal faults, rafts, diapirs, fisher-street, and liquefaction vents, are traced and measured in a purpose of strain-stress analysis. Gravitationally driven slumping deformations are essentially generated by shear mechanism, which was found accelerating in both directions of toe-front and the decollement surface. The shear-related structures are traced in complex patterns and frequent existence near the decollement surfaces and own intricated contractional features near the toe-front. Proceeding of glided slabs from the head of gliding (extensional strain), to the toe-front (compressional domain) have been resulted in overprinting of the extensional structures by superimposed contractional forms. Successive slumps are representing by very complex tectonic patterns. The Eocene sequences encompass demonstrative synsedimentary slump structures and olistostromes indicating Eocene tectonics. It can be concluded that the Eocene basin and intrabasinal ridges had been equated by Eocene tectonics that caused ridge uplifting, denudation and block-detachment. These charged the warped seabed basinal troughs and triggered gravitational tectonics and formation of olistostromes. Gravitational tectonics within the open marine Lower Miocene sediments are attributed to basin - slopes that created by rapid subsidence and downward movements along the bounding rift-related faults.
The northern part of the Hammam Faraun block is divided structurally into eight sub-blocks, each sub-block has characteristic structures and dip direction(s). These sub-blocks are: the Gabel Hammam Faraun-Gabel Thal, El Hagrah-El Ganobia, Wadi Thal, El Gushia, El Mreir-El Muntalaa, El Tayiba-Rod El Awad, Abu Ideimat-Musabaa Salama and Rift margin sub-blocks. Detailed field mapping of these sub-blocks indicate that the Pre-rift and Syn-rift rocks are highly deformed by faults and subordinated folds related mainly to the movements on nearby fault. These faults are mainly normal dip- slip and, in few cases, oblique-slip faults, in addition, there are two small-scale thrust faults. Faults oriented NW, NNW, NNE, ENE and WNW. Slickenlines indicate that the NW set are normal, or right-lateral or left-lateral, those of the NNW and NNE sets are normal and left-lateral, and those of the WNW set are right-lateral or normal or left-lateral. There are seven large-scale transfer zones, four of those are synthetic and the remaining three are an antithetic. Relay ramps, trap door faults, transfer faults, accommodation zones and twist zones are found in the area due to the interact of the large-scale faults.
Folding plays an important role in the deformation and their axes are oriented NW, NNE and NE. Most of these folds are plunging synclines and plunging anticlines whereas the synclines are usually longer than anticlines. The plunge angles for 42 folds were measured in the field and range from 10° to 30°. The length of mapped folds range from 0.1 to 11.6 km. In the most common geometry the fold axes lie parallel to or sub-parallel to the strike of nearby faults but another groups has fold axes lie perpendicular to the strike of the fault. Monoclines in the mapped area formed due to draping of bedding over normal faults.
Detailed structural analyses of the mapped area indicate that the study area has two main ridges trending in NNE and NE directions oblique to the direction of the Gulf of Suez rift. The first one, the Gabel Hammam Faraun-Gabel Thal sub-block, is structurally controlled. The olistostromes indicate the ridge was active during deposition of the Early-Middle Eocene Waseiyit Formation and uplifted after Eocene times. Because it is intruded by volcanicity, contains outcrops of the oldest rock units and some Miocene sediments are preserved in the overlapping areas. So, we can describe this ridge as intra-basin ridge, and it may be extend into the offshore area.
This ridge separates two large Miocene basins, which have the same direction as the Gulf of Suez rift. If a basin forms as a result of faulting then its direction should be similar to the trend of the faults. So, we can suggest that, these basins formed according to the geometry of the depositional surface after Eocene times and this geometry was fault controlled. There is additional evidence that fault controlled topography was prevalent at this time. Basaltic lava of Oligo-Miocene age fills a graben and faulted Tayiba Formation lies beneath the Early Miocene Nukhul Formation. The two basins were connected together in the northern part of the study area and the dip increases northwards as well. The major synclines that dominate the Miocene basins have the same trend as the rift.
The second ridge, the El Hagrah-El Ganobia sub-block, is structurally and topographically lower than the first one and capped by Quaternary terraces. The hanging wall of the northern boundary fault has several small-scale folds that trend almost perpendicular to the fault. These folds are related to displacement gradients on a segmented fault, which sets up fold trains within the fault walls but in these cases the hinges lie at high angles to the fault.
On the eastern side of the map the Miocene-bounding fault (F10) is exposed. Whereas Miocene sediments can be found in its hanging wall there are no Miocene sediments to the NE of this fault. This fault dips to the SW and extends to the NW until dies in a transfer zone where another fault (F15) is born which dips to the NE. All of the rocks that lie to the NE of the F10-fault dip to the NE as a result of drag on its surface and forming rollover anticline.
The rift shoulder fault (F14) lies in the southeastern portion of the study area in a crescentic shape. The displacement on the fault is larger to the south and decreases northwards. In the northeastern corner of the map there is no rift shoulder fault and the rocks are horizontally and dip to the west to form a large relay ramp. This dip can be observed in both the hanging wall and footwall of fault F15 and the Miocene sediments overlap the pre-rift rocks in footwall of F15-fault. This arrangement suggests that footwall uplift due to movements on F15-fault may have formed the northeastern limit of the Miocene sediments in the absence of the Miocene-bounding fault which ends at Wade Waseiyit. The absence of the Nukhul Formation in the southern part of the study areas suggests that during Miocene times the syn-depositional surface may have had a northward dip. This dip was imposed by fault-controlled uplift of the southeastern portion of the study area. A similar arrangement is indicated by the distribution of the Abu Alaqa Formation. Fan-glomerates that are derived from the denudation of the rift shoulder, this means large shoulder uplifting due south.