Eocene Limestones Research Articles

Geomorphological Aspects at the Giza Plateau in Egypt during the Age of Pyramid Building

The constructions of Giza pyramids were architectural landscape projects. Old Kingdom monarchs made effective use of Eocene limestone bedrocks, called Moqattam and Maddi Formation.

Batfishes from the Eocene of Monte Bolca

AbstractBatfishes of the family Ogcocephalidae are derived lophiiform fishes characterized by having a dorsoventrally depressed body and a distinctive series of morphological features. A new genus and species of batfish,Tarkus squireigen. et sp. nov., is described from the Eocene (Ypresian) limestone of the celebrated locality of Monte Bolca, Italy. It is based on five well-preserved specimens that display a unique combination of characters (body moderately depressed; disk rounded in outline; caudal peduncle thick and stout; frontals with median groove for the illicium; teeth present on jaws and palate; illicial bone pitted and trilobate; body covered with thick slightly overlapping tubercles) that support its recognition as a new genus of the family Ogcocephalidae.Tarkusgen. nov. is also characterized by having distally branched pectoral-fin rays, a condition unique within the family, and by a peculiar structure of the axial skeleton, which possibly represents the plesiomorphic state for the ogcocephalids.Tarkusgen. nov. shows a certain degree of phenetic affinity with the extant shallow-water batfish generaHalieutaeaand (more particularly)Halieutichthys. The specimens of this taxon are the first articulated skeletal remains of the Ogcocephalidae ever recorded as fossils, also representing the oldest members of the family known to date. The general structure of the skeleton ofTarkusgen. nov. provides unambiguous evidence that the existence of the modern ogcocephalid body plan was already established in the early Eocene, and probably originated well before that period. Palaeoenvironmental considerations suggest thatTarkusgen. nov. was a tropical batfish that inhabited the inner-shelf palaeobiotopes of the central-western Tethys.

Sedimentary basins of Yemen: their tectonic development and lithostratigraphic cover

This paper describes the updated stratigraphy, structural framework and evolution, and hydrocarbon prospectivity of the Paleozoic, Mesozoic and Cenozoic basins of Yemen, depicted also on regional stratigraphic charts. The Paleozoic basins include (1) the Rub’ Al-Khali basin (southern flanks), bounded to the south by the Hadramawt arch (oriented approximately W–E) towards which the Paleozoic and Mesozoic sediments pinch out; (2) the San’a basin, encompassing Paleozoic through Upper Jurassic sediments; and (3) the southern offshore Suqatra (island) basin filled with Permo-Triassic sediments correlatable with that of the Karoo rift in Africa. The Mesozoic rift basins formed due to the breakup of Gondwana and separation of India/Madagascar from Africa–Arabia during the Late Jurassic/Early Cretaceous. The five Mesozoic sedimentary rift basins reflect in their orientation an inheritance from deep-seated, reactivated NW–SE trending Infracambrian Najd fault system. These basins formed sequentially from west to east–southeast, sub-parallel with rift orientations—NNW–SSE for the Siham-Ad-Dali’ basin in the west, NW–SE for the Sab’atayn and Balhaf basins and WNW–ESE for the Say’un-Masilah basin in the centre, and almost E–W for the Jiza’–Qamar basin located in the east of Yemen. The Sab’atayn and Say’un–Masilah basins are the only ones producing oil and gas so far. Petroleum reservoirs in both basins have been charged from Upper Jurassic Madbi shale. The main reservoirs in the Sab’atayn basin include sandstone units in the Sab’atayn Formation (Tithonian), the turbiditic sandstones of the Lam Member (Tithonian) and the Proterozoic fractured basement (upthrown fault block), while the main reservoirs in the Say’un–Masilah basin are sandstones of the Qishn Clastics Member (Hauterivian/Barremian) and the Ghayl Member (Berriasian/Valanginian), and Proterozoic fractured basement. The Cenozoic rift basins are related to the separation of Arabia from Africa by the opening of the Red Sea to the west and the Gulf of Aden to the south of Yemen during the Oligocene-Recent. These basins are filled with up to 3,000 m of sediments showing both lateral and vertical facies changes. The Cenozoic rift basins along the Gulf of Aden include the Mukalla–Sayhut, the Hawrah–Ahwar and the Aden–Abyan basins (all trending ENE–WSW), and have both offshore and onshore sectors as extensional faulting and regional subsidence affected the southern margin of Yemen episodically. Seafloor spreading in the Gulf of Aden dates back to the Early Miocene. Many of the offshore wells drilled in the Mukalla–Sayhut basin have encountered oil shows in the Cretaceous through Neogene layers. Sub-commercial discovery was identified in Sharmah-1 well in the fractured Middle Eocene limestone of the Habshiyah Formation. The Tihamah basin along the NNW–SSE trending Red Sea commenced in Late Oligocene, with oceanic crust formation in the earliest Pliocene. The Late Miocene stratigraphy of the Red Sea offshore Yemen is dominated by salt deformation. Oil and gas seeps are found in the Tihamah basin including the As-Salif peninsula and the onshore Tihamah plain; and oil and gas shows encountered in several onshore and offshore wells indicate the presence of proven source rocks in this basin.

Petrography and geochemistry of Eocene limestone from Khashm Al-Raqaba area, El-Galala El-Qibliya, Egypt

The Khashm Al-Raqaba area lies in the central part of El-Galala El-Qibliya Plateau (Southern Galala, Egypt). It contains a huge reserve of hard crystalline light-colored limestones. The studied limestones are differentiated into three lithofacies as follows: Nummulitic-biomicrudite facies (packstone), Nummulitic-bioclastic micrite facies (wackestone) and fossiliferous micrite facies (wackestone). The rocks were subjected to extensive diagenetic processes with varying intensities, the most important of which are compaction (chemical and mechanical), neomorphism, internal filling and stylolitization. X-ray diffraction analysis of the studied limestones revealed that calcite is the main carbonate mineral in the studied rocks and is considered as low-magnesian type. Quartz and clay minerals are the main non-carbonate minerals concentrated along the stylolite seams as insoluble residues, while kaolinite, montmorillonite, and illite are the main clay minerals forming the joint-filling materials. The chemical analysis of the limestone samples revealed high calcium content, low magnesian content, low content of acid insoluble residues, and consequently low SiO2 and Al2O3 contents. Very low contents of total Na2O and Cl indicate a contribution of freshwater. The low value of total Sr content in the selected rock samples may indicate depletion of Sr during diagenetic processes.

Appraisal and development of the Taq Taq field, Kurdistan region, Iraq

Abstract The Taq Taq Field is located within an anticline in the gently folded zone of the Zagros mountains, northeastern Iraq, approximately 50 km ESE of Erbil. The main reservoirs are fractured limestones and dolomites of Late Cretaceous age, with an oil column exceeding 500 m in thickness. Eocene limestones and dolomites at shallow depth form a subsidiary reservoir. The structure is a gentle thrust-related fold which has also been affected by dextral transpression. A pervasive fracture system is present within the reservoirs, giving good connectivity and deliverability. Initial discovery and appraisal was made in 1978 when three wells were drilled. The recent appraisal programme started in 2005 and by the end of 2008 two seismic surveys had been acquired and eight additional wells had been drilled. Mapping has incorporated a seismic principal component analysis for horizon and lithology identification. Modelling of the fractures has utilized a comprehensive data set derived from core and image logs. Special core analysis has been directed towards the understanding of the pore system and its interaction with the fractures. Synthesis of all these elements is performed in a dual-media dynamic model which is currently in use for development planning.

Larger foraminiferal biostratigraphy of the lower Tertiary of Jaintia Hills, Meghalaya, NE India

Larger foraminifera of the Tertiary a1 (Thanetian) to Tertiary b (Priabonian) of the Far Eastern Letter Stages are recognized in the upper Paleocene to upper Eocene limestones of Jaintia Hills, Meghalaya. The occurrence of Pellatispira preceded both occurrences of Lepidocyclina spp. and Nummulites fabianii. Three new genera and species, Meghalayana indica, n. gen., n. sp., Raoia indica, n. gen., n. sp., and Protogypsina indica, n. gen., n. sp. are described after Orbitosiphon tibetica, Paleocene orbitoidal foraminifera as a group with Orbitosiphon.

Basement Types, Lower Eocene Series, Upper Eocene Olistostromes and the Initiation of the Southern Thrace Basin, NW Turkey

The Eocene sequence of the southern Thrace Basin unconformably overlies two types of basement: (1) Slate, limestone and phyllite crop out in small inliers under the Upper Eocene conglomerates and limestones in the Mecidiye region, north of Saros Bay. These low-grade metamorphic rocks form the eastern extension of the Circum-Rhodope Belt of Greece. (2) In the Şarköy region south of the Ganos Fault, tectonically elevated basement consisting of serpentinite, metadiabase and Upper Cretaceous blueschists is unconformably overlain by the upper Bartonian to lower Priabonian shallow marine limestones of the Soğucak Formation. In some places erosional remnants of an upper Ypresian transgressive sequence (the newly discovered Dişbudak series) underlie the Soğucak Limestones. This Dişbudak series starts with sandstone and conglomerate and passes up into sandy limestone, marl and shale. Hydrocarbon exploration wells south of the Ganos Fault have also encountered an ophiolitic mélange basement under the Dişbudak series and/or under the Soğucak Formation. The Ganos Fault forms the boundary between the two basement types. The Soğucak Limestone is overlain by an Upper Eocene to Early Oligocene flysch sequence with olistostromes. The clasts in the flysch include the Soğucak Limestone, Cretaceous and Palaeocene pelagic limestone, serpentinite, basalt, gabbro, greywacke, quartz-diorite and greenschist. They range in size from sand grains to olistoliths up to one kilometre across. Composite olistoliths consist of pelagic limestone or basalt overlain by the Upper Eocene limestone. The Upper Eocene mass flows were probably formed in an extensional setting and were derived from the south from the flanks of large normal faults related to the opening of the southern Thrace Basin. The Dişbudak series is absent along the observed basement-Eocene contacts, which implies that the main transgression leading to the development of the southern Thrace Basin started in the late Bartonian.

Geotechnical investigation of sewage wastewater disposal sites and use of GIS land use maps to assess environmental hazards: Sohag, upper Egypt

Land application is the only currently available technique for sewage wastewater disposal along the Nile Valley in Upper Egypt. Wastewater disposal projects have been established in the lowland desert zone extending between the cultivated floodplain and the Eocene Limestone plateau. The plan is to use the treated wastewater in irrigating woody farmlands. Some wastewater disposal sites are already operating, and several others will be established in the near future. The proposed wastewater disposal sites are located in a sensitive desert zone that is extremely narrow and situated very close to vital resources including the cultivated floodplain, reclaimed lands, residential areas, and surface water resources. In addition, the subsurface sediments of this zone (Pleistocene sand–gravel succession) constitute a significant part of the Quaternary aquifer of the valley. The objective of this study is to characterize and investigate the wastewater disposal sites and assess their probable environmental hazards. The study showed that the available lands are insufficient to accommodate the projected quantities of wastewater. At the currently operating sites, excess raw wastewater is accumulating on the ground surface forming large uncontrolled ponds. Such wastewater ponds represent a potential environmental hazard and might cause disastrous health effects, where chemical and bacteriological pollution of soil, crops and water resources may occur.

New Insights into Karst and Caves of Northwestern Zagros (Northern Iraq)

During 2002, several reconnaissance speleological explorations were undertaken by the authors and local enthusiasts in the karst of Northwestern Zagros in Northern Iraq. Some of the caves were visited for the first time and explored to a great depth by the scientists, while the Shanidar cave is a world-famous site representing one of the oldest discovered and investigated human settlements. The explored caves are located in well-karstified limestones of the Cretaceous age as well as in younger Eocene limestones. This paper contains the data from the nine largest caves. Their total explored lengths range from a few tens of meters up to several hundred meters. Four caves are fossil, containing only percolated water, while five represent still hydrogeologically active features. Two of them have resulted from the dissolution of carbonate or evaporate rocks stimulated by water oversaturated in H2S which migrated from deeper oil-bearing structures.

Contrasting Late Cretaceous–Palaeocene lithostratigraphic successions across the Bibai Thrust, western Sulaiman Fold–Thrust Belt, Pakistan: Their significance in deciphering the early-collisional history of the NW Indian Plate margin

The Sulaiman Fold–Thrust Belt is a significant tectonic element in northwest Pakistan, located on the NW margin of the Indian Plate having a rift–drift-collision plate tectonic history. Late Cretaceous–Palaeocene successions in the western sector of this Belt conventionally comprise strata above the widespread pelagic Parh Limestone (Albian–Campanian) and below the fluvio-deltaic Ghazij Formation (Early Eocene). These successions display marked lithostratigraphic variations across the Bibai Thrust, long known to be an important structural feature in the western Sulaiman Belt. The successions on the foot wall, to the east and southeast of the Bibai Thrust (Quetta, Spera Ragha and Chinjun areas), exhibit the most variable lithostratigraphy, were deposited exclusively in shallow marine conditions and include volcanics associated with a local submarine edifice. They also display several internal disconformities, locally accompanied by oxidised units that attest to intermittent emergence. By contrast, coeval successions on the hanging wall, to the north and northwest of the Bibai Thrust (Urghargai–Mazu Ghar and Kach–Ziarat areas) are the products of deposition in deeper marine conditions and also include important volcanigenic contributions. These contrasting lithofacies accumulated respectively in widely separated proximal and distal sectors of the north-western margin of the Indian Plate and their current proximity is attributed to tectonic juxtaposition by relative southward translation of the distal facies along the Bibai and related thrusts. Involvement of Late Eocene limestones in these thrusts and their sealing by Mio-Pliocene fluvial sediments demonstrates that active translation on these thrusts continued at least into Late Eocene or Oligocene times.

Alteration of Triassic carbonates in the Buda Mountains —a hydrothermal model

Large, irregular volumes of altered, friable Triassic dolomite with poorly recognizable depositional fabrics crop out in the Buda Mountains, Hungary. These rock volumes are characterized by powder-like, chalky, soft, whitish gray microporous carbonates, referred to as “pulverized dolomite”. This is interpreted as the result of corrosion of carbonates along microfractures. The pulverized dolomite is commonly associated with silica and clay cementation (“silicification”) and “mineralization” of ironrich minerals, barite, sphalerite, galena, fluorite, calcite, dolomite and others, clearly pointing out hydrothermal Mississippi Valley Type (MVT) conditions. The pulverization, silicification and mineralization are considered to be a diagenetic facies association (PSM facies). Tectonic shear corridors played an important role in the development of PSM facies as carriers of hydrothermal fluids, but the geometry of the altered units is very irregular and cross-cuts different Triassic depositional facies in addition to Eocene limestone and Middle-Upper Miocene sediments. The PSM facies represents the early stages of hydrothermal alteration (i.e. the burial phase) that was later modified by thermal mixing zones. Pulverized dolomite bodies that reached the surface were strongly affected by meteoric fluids; peculiar speleo-concretions were formed by calcite cementation of the powdery dolomite clasts. The altered carbonates show major porosity development whereas the unaltered carbonates present only minor porosity. The size and lithologic contrast of the altered geobodies makes them detectable by geophysical methods of mineral and hydrocarbon exploration.

Record of Cenozoic sedimentation from the Amanos Mountains, Southern Turkey: Implications for the inception and evolution of the Arabia–Eurasia continental collision

The sedimentary succession of the southern Amanos Mountains, bordering the eastern margin of the Karasu Rift in south central Turkey, provides a record of environmental change from the Eocene (Lutetian) to the Upper Miocene (Tortonian) that charts the final evolution of the northern margin of the Arabian plate prior to and during continental collision. Eocene shallow-marine carbonates (Hacıdağı Formation) are interpreted as the youngest unit of the Arabian passive margin succession deposited on a northwards facing carbonate ramp. Subsequent deformation and uplift took place during the Oligocene represented by folding of the Eocene and older strata. This is interpreted to be the result of initial continental collision between Arabia and Eurasia. Unconformably overlying the Eocene limestone are Lower Miocene conglomerates, sandstones and palaeosols up to 150 m thick (Kıcı Formation). These were deposited in a range of marginal marine settings consisting of alluvial fan/fan delta facies, flood plain as well as basinal facies. Subsequently, during the Middle Miocene, local patch reefs developed in restricted areas (Kepez Formation) followed by Upper Miocene sediments (Gökdere Formation) composed of relatively deep water hemipelagic marl, with clastic interbeds, which represent a transgression during this period. The Upper Miocene becomes sandier upwards, this records the regression from the relatively deep water facies to coastal sediments. Water depth gradually became shallower until during Pliocene time the area became continental in nature. By the Quaternary rifting had resulted in the development of the Karasu Rift with active alluvial fans along the margins and braided rivers depositing coarse conglomerates in the axial zone. These conglomerates are interbedded with basaltic lava flows that resulted from the region extension across the area. This research shows that initial continental collision occurred in this area after the Lutetian (40.4 Ma) and before the Aquitanian (23.03 Ma) supporting the hypothesis that the southern Neotethys Ocean closed during the Late Eocene to Oligocene. This was a time of climatic change including the onset of southern hemisphere glaciation, in which the closure of the southern Neotethys may have had played an important role.

The influence of aluminium industry and bedrock lithology on the oxide content in the urban soil of Sibenik, Croatia

The content of major element oxides (Al2O3, SiO2, CaO, MgO, Fe2O3, P2O5, K2O, TiO2, and MnO) in soil surrounding the light metal factory (TLM), which was producing aluminium from 1937 till 1991, was investigated by EDXRF and XRD. The evaluation of a possible aluminium pollution linked to the industrial activity was studied by a comparison of soil around the TLM with control soil samples. Taking into account natural variations caused by bedrock lithology, control samples were taken in the soil developed upon the Upper Cretaceous limestones and Middle Eocene flysch deposits, while the TLM soil was sampled over the Upper Cretaceous and Early to Middle Eocene limestones; that way the samples constituted four groups, each containing five to seven samples. Control soil overlying flysch deposits differed strikingly from the other three groups by its increased CaO values, and decreased content of Al, Fe, Mn, and Ti-oxides, confirming the overall geochemical imprint of bedrock lithology on the analysed soils. However, a specific mineral composition (presence of alumina) of the TLM soil, together with peculiar correlations among Al2O3 and other oxides indicates a certain extent of aluminium pollution of the investigated area.

Factors controlling building susceptibility to earthquakes: 14-year recordings of Islamic archaeological sites in Old Cairo, Egypt: a case study

Cairo City has a large number and different forms of Islamic archaeological sites, in particular, at El-Gammalia and El-Moez streets, as well as Coptic archaeological sites, e.g. at Mari Gergis. Human interference and activities at these historical areas resulted in flooding such sites’ foundations with domestic water, deteriorating its basal courses by salt weathering. The 1992 earthquake is another natural environmental hazard severely affecting many of these sites. The aim of the current study is to examine some factors (of bedrock and buildings) that are expected to control building susceptibility to damage by earthquakes by taking 38 Islamic archaeological sites in the El-Gammalia area as a representative case study. Detailed field recordings of site damage category before and after the quake and continued recording of damage features generated by the 1992 quake over the last 14 years, measuring depth to sub-surface water, measuring buildings’ height before the quake and bedrock sampling at these sites for geotechnical investigations were all considered for achieving this aim. The data has been processed mathematically and graphically (using the Excel package) to examine the main factors responsible for building susceptibility to damage by earthquakes. The selected archaeological sites give an excellent representation of the factors controlling building susceptibility to damage by quakes; it is found that the sites with heights (before the quake) ranging from 12 to 14 m are the most affected ones; the sites with the highest damage category before the quake were more susceptible to more damage by the quake; the sites that had been built on alluvium soil were more affected than those built on the Eocene limestone. The age of these sites has, to a small extent, indirect control on sites’ susceptibility to damage by the quake, particularly in parts flooded with domestic water (i.e. affected by salt weathering). The depth to sub-surface water is an effective parameter on sites’ basal courses (through salt weathering), which, indirectly, control a building’s susceptibility to quakes, particularly where the depth of water ranges from 0.6 to 1.6 m in alluvium bedrock. The alluvium soil at the study area has a liquid limit ranging from 62% to 82%, plastic limit from 37% to 86% and plasticity index from 26% to 46% and free swelling from 27% to 81%. These geotechnical limits for such alluvium bedrock indicate that its clay minerals are mostly montmorrillonite.

Constraints on inner forearc deformation from balanced cross sections, Fila Costeña thrust belt, Costa Rica

The Fila Costeña thrust belt in the forearc of Costa Rica is accommodating a significant portion of the convergence of the Cocos plate and Panama microplate. Geologic mapping of the thrust belt depicts a duplex with three horses that incorporate Eocene limestones and Oligocene to early Miocene clastics inboard of the subducting Cocos Ridge axis. By constructing a cross section at this location along a NE–SW trending transect perpendicular to the thrust belt, we constrain a shortening rate of approximately 40 mm/a and propose that as much as 50% of the total plate convergence rate is taken up in the inner forearc. The Eocene limestones at the base of the thrust sheets pinch out in both directions away from the onland projection of the Cocos Ridge axis owing to decrease in slip on faults and a lateral ramp in the basal décollement. The thrust belt terminates near the Panama border at the onland projection of the subducting Panama Fracture Zone. These observations suggest that shortening is propagating to the east with the migration of the Panama triple junction and the onset of shallow subduction of the thickened edge of the Cocos plate. The absence of similar features in the Nicaraguan forearc, where the subducting crust is older, subducts more steeply, and lacks incoming ridges and seamounts, indicates that deformation of the forearc basin in Costa Rica reflects greater coupling between the converging plates inboard of the Cocos Ridge.

Pleistocene evolution of the Nile Valley in northern Upper Egypt

In the El Minia district of northern Upper Egypt, the Pleistocene deposits of the Nile Valley include (?)Early Pleistocene conglomerates of the Armant Formation and (?)Middle Pleistocene sands of the Qena Formation. These sediments are exposed along both sides of the valley in terraces at different heights, unconformably overlying Eocene limestones. Field observations suggest that the conglomerate facies of the Armant Formation was deposited in proximal and mid-alluvial fans. The sands of the Qena Formation are differentiated into two facies: a cross-bedded sandstone, representative of alluvial fan—braided stream environments, and a facies of sand interbedded with mud that may have been deposited by a meandering river. The heavy minerals of the Armant Formation are markedly different from those of the Qena Formation, suggesting derivation from different sources. Surface textures of quartz grains from the Qena sands, observed by SEM, exhibit chemical features, attributed to a fluviatile origin. Sand from the Armant Formation is characterized by mechanical and chemical surface textural features that suggest original aeolian derivation followed by later fluvial sedimentation.

Miocene shallow-water limestones from São Nicolau (Cabo Verde): Caribbean-type benthic fauna and time constraints for volcanism

Shallow-water limestones of presumed Late Cretaceous and Eocene age, interbedded with basaltic lavas, were described by earlier authors from São Nicolau in the northwestern part of the Cabo Verde archipelago. If confirmed, these ages would imply late Mesozoic shallow-marine and subaerial volcanic activity in the Cabo Verde archipelago, and document a geological history very different from that known so far from other Cabo Verde Islands, from which no subaerial volcanic activity before the mid-Cenozoic is known. Our re-investigation of the foraminiferal fauna indicates a Late Miocene age for the presumed Late Cretaceous and Eocene limestones. The hypothesis of a long-lived hot spot, active by the Early Cretaceous, and of a major island-building stage in the Cabo Verde Islands during this period, is therefore not supported by the present bio- or chronostratigraphic data.

The crustacean ichnofossil Palaxius associated with callianassid body fossils in an Eocene methane-seep limestone, Humptulips Formation, Olympic Peninsula, Washington

Crustacean microcoprolites are preserved along with crustacean megafossils in an Eocene limestone within the Humptulips Formation in Grays Harbor County, Washington. The limestone formed at a methane seep, as revealed by early diagenetic carbonate phases resembling those of other seep limestones, δ13Ccarbonate values as low as −27‰, and lipid biomarkers of prokaryotes involved in anaerobic oxidation of methane with δ13C values as low as −110‰. Recognizable crustacean megafossils are chiefly isolated chelipeds, akin to those of callianassid shrimp. The microcoprolites are pierced by ten longitudinal canals with crescent-shaped outlines in cross-section, arranged in two symmetrical groups. The symmetry plan and number of canals of the microcoprolites identify the Humptulips ichnospecies as Palaxius habanensis Bronnimann & Norton. The occurrence of decapod fossils along with microcoprolites suggests that callianassid shrimp were the producers of the Palaxius, supporting earlier work that attributed this ichnogenus to callianassids.

Mise en évidence d’une nappe de charriage à deux unités paléogènes au plateau de Lansarine (Tunisie du Nord) : définition d’un nouvel élément structural de l’Atlas tunisien et réévaluation du calendrier des serrages tertiaires

The Palaeogene plateau of the Lansarine area (northern Tunisia) is a thrust nappe formed by two Eocene limestone units, overlapping the marine Miocene series. The stacking of these two units and the coverage of the Neogene series are noticeable in several localities within the study area. The cartography permits the measurement of a NW–SE overthrust amplitude of 10 km with respect to the nearest southern overlapping of the Mateur peel thrusts, which are displaced themselves. The measured overthrust represents a minimal estimation based on the present erosion limits. These results indicate that the region has been exposed, at least, to two Tertiary compressive phases. The first one took place during the Late Eocene. This phase, which was characterized by a moderate folding, corresponds to the Atlasic phase. The second major phase, which has been dated to the Tortonian age, is responsible for the tangentially carrying of the Palaeogene series. These new data have allowed the recognition of a new tectonic unit in the Tunisian Atlas, which is the thrust nappe of the Jebel Lansarine.

RESPONSE OF A NEWLY RECLAIMED CALCAREOUS SOIL AT THE EASTERN RIM OF EL FAYOUM DEPRESSION TO AGROCHEMICAL AMENDMENT FOR SUSTAINING ITS AGRICULTURAL UTILIZATION

Agricultural utilization of desert marginal soils at El FayoumGovernorate edges is of importance to support the local farmer incomes,particularly under the best and suitable management practices of land andavailable water resources. The choice a newly reclaimed soil encompassingby Eocene limestone at the eastern edge of Tamia district was a matter ofconcern in this work. It is a sandy clay loam in texture, slightly saline, nonsodic, and calcareous in nature with a subsurface diagnostic horizon ofcalcigypsic one, and classified as Typic Calcigypsids, fine loamy, mixed,heperthermic, moderately deep. According to a parametric system, it couldbe evaluated as moderately suitable (S2ws