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Journal of African earth sciences 37건

  1. [해외논문]   Holocene evolution of Dahab coastline – Gulf of Aqaba, Sinai Peninsula, Egypt   SCIE

    Torab, Magdy
    Journal of African earth sciences v.139 ,pp. 254 - 259 , 2018 , 1464-343x ,

    초록

    Abstract Dahab is a little Bedouin-village in Sinai Peninsula on the east coast of the Gulf of Aqaba and it lies approximately 90 km north of Sharm-el-Sheikh City. Dahab means “gold” in the Arabic language; over the past 20 years it has become one of the most visited tourist sites in Egypt. The basement complex is composed mostly of biotite aplite-granite, mica-aplite granite, granodiorite, quartz diorite, alaskite, and diorite. This composition correlates to similar igneous rocks in the most southern areas of Sinai and the Red Sea. Wadi Dahab is composed of igneous and metamorphic rocks and the coastline is formed of fragments of its rocks mixed with fragments of coral reef. The morphology of Dahab's coastline is characterized by a hooked marine spit composed of fluvial sediments carried by marine currents from the mouth of Wadi Dahab. This spit encloses a shallow lagoon, but the active deposition on the lagoon bottom will turn it into saline marsh. This paper investigates the evolution of the Dahab spit and lagoon during the Holocene and over the last 100 years, as well as the potential impacts of future management of the coastal area. The coastline mapping during the study was dependent on GIS techniques and data were collected by using total station, aerial photographs and satellite image interpretation as well as soil sample dating. Highlights Define rates of coastal deposition by sea currents and tides. Understand the geomorphological evolution of the Dahab coastline during the Holocene. Reconstruct the geomorphic evolution of the coastline of Dahab area.

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  2. [해외논문]   Petrogenesis of Alta'ameem meteorite (Iraq) inferred from major, trace, REE and PGE+Au content   SCIE

    Kettanah, Yawooz A. (Department of Applied Geosciences, College of Spatial Planning & Applied Sciences, Duhok University, Duhok, Iraq ) , Ismail, Sabah A. (Dean of the College of Education for Pure Sciences, Kirkuk University, Kirkuk, Iraq)
    Journal of African earth sciences v.139 ,pp. 260 - 274 , 2018 , 1464-343x ,

    초록

    Abstract Alta'ameem Meteorite (AM) is an unaltered ordinary LL chondrite that hit an area near Kirkuk City in northern Iraq on 1977. It has an ash-gray colour with a thin black fusion crust, and consists of spheroidal chondrules and variously shaped clasts aggregated together by a fine grained matrix. The chondrules of Alta'ameem Meteorite include all known types in similar meteorites elsewhere. Mineralogically, the AM consists of silicates (olivine - Fa 27.7 ; pyroxene - Fs 23.2 (Opx) and 20.5 (Cpx) ; plagioclase - Ab 73.5 An 22.1 Or 4.7 ), alloys and metals (taenite, tetrataenite, kamacite, and native copper), oxides (ilmenite and chromite), sulfides (troilite), and phosphates (apatite) as well as few unidentified minerals including a Fe-Ti-Cr oxide and Fe-Ni sulfide. The chemistry of AM is dominated by SiO 2 , MgO, and FeO t accounting for >91 wt% of the bulk composition with minor amounts of Al 2 O 3 , CaO, Na 2 O, S, Ni and Cr. It contains 3675 ppb REE which is within the range of most chondrites, with a negative (−0.8) Sm- and positive (+1.2) Tb-anomalies and a near flat normalized trend (La N /Yb N = 1.16). The concentration of PGEs and Au, Ni, Co, and Cr is low in comparison to most chondrites. The K/La, Ru/Rh vs. Pt/Pd, and Pd/Ir ratio (1.85), and low PGE indicates that the AM is somewhat distinct from other meteorites. The AM has W0 weathering grade and very weak (S2) shock metamorphism. Although the AM has some petrographical and geochemical differences with other chondrites, it still can be considered as LL5 chondrite. Highlights Alta'ameem Meteorite (AM) is a LL5 chondrite that hit northern Iraq on 1977. Th AM is studied petrographically, mineralogically and geochemically. The AM contains silicates, native metals, Fe-Ni alloys, sulfides, phosphates & oxides. The predominant minerals in AM are olivine, pyroxene and minor plagioclase. The AM is richer in LILE and poorer in HSE relative to average LL-chondrites. Graphical abstract [DISPLAY OMISSION]

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    회원님의 원문열람 권한에 따라 열람이 불가능 할 수 있으며 권한이 없는 경우 해당 사이트의 정책에 따라 회원가입 및 유료구매가 필요할 수 있습니다.이동하는 사이트에서의 모든 정보이용은 NDSL과 무관합니다.

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  3. [해외논문]   A recent Mw 4.3 earthquake proving activity of a shallow strike-slip fault in the northern part of the Western Desert, Egypt   SCIE

    Ezzelarab, Mohamed (Sultan Qaboos University, Earthquake Monitoring Center, 50 Alkouhd, 123, Muscat, Oman ) , Ebraheem, Mohamed O. (Assiut University, New Valley Branch, Faculty of Science, Geology Department, Assiut, Egypt ) , Zahradní (Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic) , k, Jiř , í
    Journal of African earth sciences v.139 ,pp. 275 - 282 , 2018 , 1464-343x ,

    초록

    Abstract The Mw 4.3 earthquake of September 2015 is the first felt earthquake since 1900 A.D in the northern part of the Western Desert, Egypt, south of the El-Alamein City. The available waveform data observed at epicentral distances 52–391 km was collected and carefully evaluated. Nine broad-band stations were selected to invert full waveforms for the centroid position (horizontal and vertical) and for the focal mechanism solution. The first-arrival travel times, polarities and low-frequency full waveforms (0.03–0.08 Hz) are consistently explained in this paper as caused by a shallow source of the strike-slip mechanism. This finding indicates causal relation of this earthquake to the W-E trending South El-Alamein fault, which developed in Late Cretaceous as dextral strike slip fault. Recent activity of this fault, proven by the studied rare earthquake, is of fundamental importance for future seismic hazard evaluations, underlined by proximity (∼65 km) of the source zone to the first nuclear power plant planned site in Egypt. Safe exploration and possible future exploitation of hydrocarbon reserves, reported around El-Alamein fault in the last decade, cannot be made without considering the seismic potential of this fault. Highlights The first felt earthquake at South El-Alamein City is discussed. Accurate analysis for the source position and focal mechanism is carried out. The event is located close to the previously known South El-Alamein fault. The inverted focal mechanism is a strike-slip with minor reverse component. The studied event is important for the ongoing earthquake hazard analyses in Egypt.

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  4. [해외논문]   The elemental geochemistry of Lower Triassic shallow-marine carbonates from central Saudi Arabia: Implications for redox conditions in the immediate aftermath of the latest Permian mass extinction   SCIE

    Eltom, Hassan A. (Kansas Interdisciplinary Carbonates Consortium (KICC), University of Kansas, Department of Geology, 1475 Jayhawk Boulevard, Lawrence, KS 66045, USA ) , Abdullatif, Osman M. (Geology Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia ) , Babalola, Lamidi O. (Geology Department, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia)
    Journal of African earth sciences v.139 ,pp. 283 - 306 , 2018 , 1464-343x ,

    초록

    Abstract The southern margin of the Tethys Ocean was occupied by a broad, shallow continental shelf during the Permian-Triassic boundary interval, with the area of present-day Saudi Arabia located from 10° to 30° south of the paleo-equator. The strata deposited in modern Saudi Arabia in the aftermath of the latest Permian mass extinction (LPME) are dominated by oolitic microbialite limestone (OML), which are overlain by skeletal oolitic limestones (SOL) capped by dolostones and dolomitic limestones (DDL). This succession reflects changes in depositional setting, which can be potentially tied to redox conditions using redox sensitive trace elements and rare earth elements (REEs). Statistical analyses reveals that trace elements and REEs are associated with detrital material, and possibly with diagenetic minerals as well. Proxies such as the Y/Ho, Pr/Pr*, Sm n /Yb n , La n /Sm n and La n /Yb n ratios indicate that REEs do not record a seawater-like pattern, and cannot be used as redox indicator. The presence of a normal marine fauna implies oxic conditions during deposition of the DDL and SOL units. However, the OML unit, which represents the immediate aftermath of LPME, lacks both a normal marine fauna and reliable geochemical signals, making it difficult to infer redox conditions in the depositional environment. Similar to published data from sections that reflect shallow marine condition in the LPME of the Tethys Ocean, chemical index of alteration values are consistently high throughout the study succession, suggesting globally intense chemical weathering in the aftermath of the LPME. As a result, geochemical redox proxies in shallow marine carbonates of the Tethys Ocean are likely to be contaminated by detrital material that have been generated by chemical weathering, and thus, other methods are required to determine depositional redox conditions. Highlights Redox sensitive elements (RSE) of Permian-Triassic boundary interval, Saudi Arabia. The studied interval represent shallow marine carbonate of the Tethys Ocean. Chemical index of alteration (CIA) was evaluated to understand the source of RSE. RSEs are associated with detrital material. CIA suggested chemical weathering, thus RSEs cannot be used as redox indicator.

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  5. [해외논문]   Resistivity imaging of Aluto-Langano geothermal field using 3-D magnetotelluric inversion   SCIE

    Cherkose, Biruk Abera (Graduate School of Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan ) , Mizunaga, Hideki (Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819-0395, Japan)
    Journal of African earth sciences v.139 ,pp. 307 - 318 , 2018 , 1464-343x ,

    초록

    Abstract Magnetotelluric (MT) method is a widely used geophysical method in geothermal exploration. It is used to image subsurface resistivity structures from shallow depths up to several kilometers of depth. Resistivity imaging using MT method in high-enthalpy geothermal systems is an effective tool to identify conductive clay layers that cover the geothermal systems and to detect a potential reservoir. A resistivity model is vital for deciding the location of pilot and production sites at the early stages of a geothermal project. In this study, a 3-D resistivity model of Aluto-Langano geothermal field was constructed to map structures related to a geothermal resource. The inversion program, ModEM was used to recover the 3-D resistivity model of the study area. The 3-D inversion result revealed the three main resistivity structures: a high-resistivity surface layer related to unaltered volcanic rocks at shallow depth, underlain by a conductive zone associated with the presence of conductive clay minerals, predominantly smectite. Beneath the conductive layer, the resistivity increases gradually to higher values related to the formation of high-temperature alteration minerals such as chlorite and epidote. The resistivity model recovered from 3-D inversion in Aluto-Langano corresponds very well to the conceptual model for high-enthalpy volcanic geothermal systems. The conductive clay cap is overlying the resistive propylitic upflow zone as confirmed by the geothermal wells in the area. Highlights Resistivity distribution in high-enthalpy geothermal systems is governed by hydrothermal alteration. The information on the Earth's resistivity obtained by magnetotelluric (MT) method has been valuable in detecting hydrothermal alteration zones in such systems. The resistivity model recovered from 3-D inversion in Aluto-Langano corresponds very well to the conceptual model for high-enthalpy volcanic geothermal systems and geological information.

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  6. [해외논문]   Timing of volcanism and initiation of rifting in the Omo-Turkana depression, southwest Ethiopia: Evidence from paleomagnetism   SCIE

    Erbello, Asfaw (Adama Science and Technology University, School of Applied Natural Sciences, Department of Applied Geology, P.O. Box 1888, Adama, Ethiopia ) , Kidane, Tesfaye (School of Earth Sciences, Faculty of Science, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia)
    Journal of African earth sciences v.139 ,pp. 319 - 329 , 2018 , 1464-343x ,

    초록

    Abstract Lava flows of the Gombe Group basalt cover the base of the Omo-Turkana rift in southwestern Ethiopia and northern Kenya. Paleomagnetic study results on these basalts are integrated with previous geochronologic data to better constrain the timing of volcanism and rifting in the area. A total of 80 drilled core samples were collected from nine sites. Experimental methods of Alternating Field (AF) demagnetization, Thermal (TH) demagnetization and Isothermal Remanent Magnetization (IRM) experiments are performed to unravel components of magnetizations. Two components of Natural Remnant Magnetization (NRM) directions are identified; the first one considered as Viscous Remanent Magnetization (VRM) is removed by 5–25 mT AF or a temperature of 120 °C–250 °C, the second component isolated after these steps defined a straight-line segment directed towards the origin and is interpreted as the Characteristic Remanent Magnetization (ChRM). In the IRM Acquisition experiment all analyzed samples showed a sharp rise in acquisition and reached to their saturation magnetization by an applied field of 300 mT. This together with the AF demagnetization and TH demagnetization behaviors suggest pseudo single domain titanomagnetite as a dominant magnetic carrier of the remanence. From a total of nine sites, six sites are reversed polarity, two sites are normal polarity and pass the reversal test of McFadden and McElhinny (1990) while one site is of erratic behavior probably due to lightning strike. The mean direction for the reversed polarity is D S = 186.1°, I S = −1.9° (N = 2, K S = 38.8, α 95 = 10.9°) and that for the normal polarity is D S = 348.4°, I S = 4.6° (N = 6, K = 378.9, α 95 = 12.9°). The overall mean direction D S = 1.7°, I S = 2.6° (N = 8, K S = 34.2, α 95 = 9.6°), is statistically identical to the expected mean direction Ds = 2.1°, Is = 7.8° (N = 26, α 95 = 2.3) obtained from the African Apparent Polar Waner Path (APWP) curve of African plate for a mean age of 4.25 Ma (Besse and Courtillot, 1991, 2003). Considering the upper age control of Moiti tuff (3.98 Ma) and Naibar tuff (4.02 Ma) which have not been intruded by the Gombe Group basalts; with the obtained paleomagnetic result the Gombe Group basalts are correlable with the late Gilbert Chron of Cande and Kent (1995) specifically at and just above the Cochiti normal sub-Chron (4.18 Ma–4.29 Ma) consistent with paleomagnetic study from the basal members of the Shungura Formation (Kidane et al., 2014). Petrographically and geochemically similar basalts (Haileab et al., 2004) in northern Kenya are reported to have the same polarity. This suggests the longitudinally distributed lava flows (Gombe Group) in Northern Kenya and southwestern Ethiopia probably had erupted in a short period between 4.18 Ma–4.29 Ma. This similarity indicates that the present architecture of the basin might have been attained soon after the emplacement of the Gombe Group basalt. Highlights Pliocene basaltic lava flows (Gombe group) outcrop around the Omo Turkana Basin. Initially variously named but have petrographic and geochemical similarity. Paleomagnetic direction and magnetic polarity is determined. Gombe group basalt emplacement timing and magnetic polarity.

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  7. [해외논문]   Sequence stratigraphic interpretation of parts of Anambra Basin, Nigeria using geophysical well logs and biostratigraphic data   SCIE

    Anakwuba, E.K. (Department of Geological Sciences, Nnamdi Azikiwe University Awka, Nigeria ) , Ajaegwu, N.E. (Department of Geological Sciences, Nnamdi Azikiwe University Awka, Nigeria ) , Ejeke, C.F. (Department of Geological Sciences, Nnamdi Azikiwe University Awka, Nigeria ) , Onyekwelu, C.U. (Sunlink Petroleum Limited, Nigeria ) , Chinwuko, A.I. (Department of Geological Sciences, Federal University Gusau, Nigeria)
    Journal of African earth sciences v.139 ,pp. 330 - 340 , 2018 , 1464-343x ,

    초록

    Abstract The Anambra basin constitutes the southeastern lower portion of the Benue Trough, which is a large structural depression that is divided into lower, middle and upper parts; and is one of the least studied inland sedimentary basins in Nigeria. Sequence stratigraphic interpretation had been carried out in parts of the Anambra Basin using data from three wells (Alo-1 Igbariam-1 and Ajire-1). Geophysical well logs and biostratigraphic data were integrated in order to identify key bounding surfaces, subdivide the sediment packages, correlate sand continuity and interpret the environment of deposition in the fields. Biostratigraphic interpretation, using foraminifera and plankton population and diversity, reveals five maximum flooding surfaces (MFS) in the fields. Five sequence boundaries (SB) were also identified using the well log analysis. Four 3rd order genetic sequences bounded by maximum flooding surfaces (MFS-1 to MFS-6) were identified in the areas; four complete sequences and one incomplete sequence were identified in both Alo-1 and Igbariam-1 wells while Ajire-1 has an no complete sequence. The identified system tracts delineated comprises Lowstand Systems Tracts (progradational to aggradational to retrogradational packages), Transgressive Systems Tracts (retrogradational packages) and Highstand Systems Tracts (aggradational to progradational packages) in each well. The sand continuity across the fields reveal sands S1 to S5 where S1 is present in Ajire-1 well and Igbariam-1 well but not in Alo-1 well. The sands S4 to S5 run across the three fields at different depths. The formations penetrated by the wells starting from the base are; Nkporo Formation (Campanian), Mamu Formation (Late Campanian to Early Maastrichtian), Ajali Sandstone (Maastrichtian), Nsukka Formation (Late Maastrichtian to Early Palaeocene), Imo Formation (Palaeocene) and Nanka Sand (Eocene). The environments of deposition revealed are from coastal to bathyal. The sands of lowstand system tract and highstand system tract found in Ajali, Nsukka, Nkporo and Imo (Ebenebe Sandstone) Formations show good continuity and as such good reservoir qualities while the shales of the transgressive system tracts which includes the Imo Formation, Mamu, and Nkporo Formations where most of the maximum flooding surfaces were delineated, can serve as seals to the numerous reservoir units. Combinations of the reservoir sands of the lowstand system tract and highstand system tract and the shale units of the transgressive system tract can form good stratigraphic traps for hydrocarbon and hence should be hydrocarbon exploration targets. Highlights Four 3rd order genetic sequences bounded by maximum flooding surfaces (MFS-1 to MFS-6) were identified in the areas. The identified system tracts delineated comprises LST, TST and HST in each wells. Five reservoir sands were identified and marked. The shales of the TST and HST will serve as a good seals to the numerous reservoir units. The environments of deposition revealed within the study area are from coastal to bathyal. Graphical abstract [DISPLAY OMISSION]

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  8. [해외논문]   Why 1D electrical resistivity techniques can result in inaccurate siting of boreholes in hard rock aquifers and why electrical resistivity tomography must be preferred: the example of Benin, West Africa   SCIE

    Alle, Iboukoun Christian (International Chair in Mathematical Physics and Applications (ICMPA - UNESCO CHAIR) 072 BP 50 Cotonou, Benin ) , Descloitres, Marc (Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE, 38000 Grenoble, France ) , Vouillamoz, Jean-Michel (Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE, 38000 Grenoble, France ) , Yalo, Nicaise (Laboratory of Applied Hydrology, Water National Institute, University of Abomey-Calavi, 01 BP 4521, Cotonou, Benin ) , Lawson, Fabrice Messan Amen (International Chair in Mathematical Physics and Applications (ICMPA - UNESCO CHAIR) 072 BP 50 Cotonou, Benin ) , Adihou, Akonfa Consolas (National Directorate of Water, Ministry of Water, 04 BP 1412, Cotonou, Benin)
    Journal of African earth sciences v.139 ,pp. 341 - 353 , 2018 , 1464-343x ,

    초록

    Abstract Hard rock aquifers are of particular importance for supplying people with drinking water in Africa and in the world. Although the common use of one-dimensional (1D) electrical resistivity techniques to locate drilling site, the failure rate of boreholes is usually high. For instance, about 40% of boreholes drilled in hard rock aquifers in Benin are unsuccessful. This study investigates why the current use of 1D techniques (e.g. electrical profiling and electrical sounding) can result in inaccurate siting of boreholes, and checks the interest and the limitations of the use of two-dimensional (2D) Electrical Resistivity Tomography (ERT). Geophysical numerical modeling and comprehensive 1D and 2D resistivity surveys were carried out in hard rock aquifers in Benin. The experiments carried out at 7 sites located in different hard rock groups confirmed the results of the numerical modeling: the current use of 1D techniques can frequently leads to inaccurate siting, and ERT better reveals hydrogeological targets such as thick weathered zone (e.g. stratiform fractured layer and preferential weathering associated with subvertical fractured zone). Moreover, a cost analysis demonstrates that the use of ERT can save money at the scale of a drilling programme if ERT improves the success rate by only 5% as compared to the success rate obtained with 1D techniques. Finally, this study demonstrates, using the example of Benin, that the use of electrical resistivity profiling and sounding for siting boreholes in weathered hard rocks of western Africa should be discarded and replaced by the use of ERT technique, more efficient. Highlights In hard rock area Electrical Profiling (EP) anomalies are often due to clayey zones. Electrical Sounding (ES) cannot estimate reliably weathered zone thickness. Electrical Resistivity Tomography (ERT) better estimates weathered zone geometry. ERT, EP and ES cannot reveal unweathered fractures. The use of ERT can save money if it improves by 5% borehole success rate.

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  9. [해외논문]   Geochemical, Sr-Nd isotopic investigations and U-Pb zircon chronology of the Takht granodiorite, west Iran: Evidence for post-collisional magmatism in the northern part of the Urumieh-Dokhtar magmatic assemblage   SCIE

    Haghighi Bardineh, Seyyed Nematollah (Corresponding author.) , Zarei Sahamieh, Reza , Zamanian, Hassan , Ahmadi Khalaji, Ahmad
    Journal of African earth sciences v.139 ,pp. 354 - 366 , 2018 , 1464-343x ,

    초록

    Abstract Subduction of Neo-Tethys lithosphere beneath the Iranian plateau during Neogene led to the formation of a NW-SE trending volcano-plutonic zone called Urumieh-Dokhtar magmatic assemblage (UDMA). The Takht granodiorite (NE of Hamedan Province, western Iran) belongs to the UDMA and has geochemical properties of post-collisional granitoids that was formed after the collision of Arabian and Iranian plateaus. This body contains rounded mafic micro-granular enclaves with relatively gradational rims indicating the effect of magma mixing/mingling in formation of the granodiorite body. The determination of U-Pb zircon age proved the Takht granodiorite was formed at Miocene (16.8 ± 0.24 Ma). The Nd-Sr isotope ratios and Sr/Nd, Nb/La and Th/U ratios of the granodiorite confirmed the magma was formed mainly by melting of continental crust, and its enclaves originated from a mantle derived mafic magma. Samples show negative anomalies in Nb, Sr, Ti, P and Eu, whereas positive anomalies in Th, K, Zr, Yb and Rb that reveals contribution of mantle and crustal materials in their generation. The Takht granodiorite has geochemical features of A2-type granites and also shows properties of both the volcanic arc and within plate magmatism association granitoids (high levels of LILEs and HFSEs). Regarding this interpretation and also post-collisional tectonic regime, it can be concluded that post-collision extensions caused deep faults in the UDMA that let mantle derived magmas rise up to the thicken crust. Such magma triggered melting in the middle crustal levels and was contaminated with crustal materials to generate granodiorite and enclave magmas respectively. The results of the current study decipher collision between the Arabian and the Iranian plateaus occurred before Miocene and the magmatism in the UDMA continued after closure of Neo-Tethys. Highlights U-Pb age Langhian - Burdigalian (16.8 ± 0.24 Ma) for the Takht granodiorite of UDMA in west Iran. Sr-Nd isotopic contents indicate the Tatkht granodiorite is from continental crust source. Determination of pre-Miocene age for time of the collision between the Arabian and Iranian plates. Graphical abstract [DISPLAY OMISSION]

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  10. [해외논문]   Depositional architecture and sequence stratigraphy of the Upper Jurassic Hanifa Formation, central Saudi Arabia   SCIE

    El-Sorogy, Abdelbaset (Geology and Geophysics Department, College of Science, King Saud University, Saudi Arabia ) , Al-Kahtany, Khaled (Geology and Geophysics Department, College of Science, King Saud University, Saudi Arabia ) , Almadani, Sattam (Geology and Geophysics Department, College of Science, King Saud University, Saudi Arabia ) , Tawfik, Mohamed (Geology Department, Faculty of Science, Zagazig University, Egypt)
    Journal of African earth sciences v.139 ,pp. 367 - 378 , 2018 , 1464-343x ,

    초록

    Abstract To document the depositional architecture and sequence stratigraphy of the Upper Jurassic Hanifa Formation in central Saudi Arabia, three composite sections were examined, measured and thin section analysed at Al-Abakkayn, Sadous and Maashabah mountains. Fourteen microfacies types were identified, from wackestones to boundstones and which permits the recognition of five lithofacies associations in a carbonate platform. Lithofacies associations range from low energy, sponges, foraminifers and bioclastic burrowed offshoal deposits to moderate lithoclstic, peloidal and bioclastic foreshoal deposits in the lower part of the Hanifa while the upper part is dominated by corals, ooidal and peloidal high energy shoal deposits to moderate to low energy peloidal, stromatoporoids and other bioclastics back shoal deposits. The studied Hanifa Formation exhibits an obvious cyclicity, distinguishing from vertical variations in lithofacies types. These microfacies types are arranged in two third order sequences, the first sequence is equivalent to the lower part of the Hanifa Formation (Hawtah member) while the second one is equivalent to the upper part (Ulayyah member). Within these two sequences, there are three to six fourth-order high frequency sequences respectively in the studied sections. Highlights The present work deals architecture and sequence stratigraphy of the Hanifa Formation in central Saudi Arabia. Fourteen facies types and five lithofacies associations were identified in a carbonate platform. The lithofacies types are arranged in two third order sequences. The first sequence is equivalent to Hawtah member, while the second sequence is equivalent to Ulayyah member.

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