Late Miocene normal faulting beneath the northern Nile Delta: NNW propagation of the Gulf of Suez Rift

The north Egyptian continental margin has undergone passive margin subsidence since the opening of Tethys, but its post-Mesozoic history has been interrupted by tectonic events that include a phase of extensional faulting in the Late Miocene. This study characterizes the geometry and distribution of Late Miocene normal faulting beneath the northern Nile Delta and addresses the relationship of this faulting to the north–northwestwards propagation of Red Sea–Gulf of Suez rifting at this time. Structural interpretation of a 2D grid of seismic reflection data has defined a Tortonian–Messinian syn-rift megasequence, when tied to well data. Normal fault correlations between seismic lines are constrained by the mapping of fault-related folds. Faults are evenly distributed across the study area and are found to strike predominantly NW–SE to NNW–SSE, with some N–S faults in the north. Faults are interpreted to be <10 km in length, typically in the range 3–6 km. This suggests that rifting in the northern Nile Delta did not proceed beyond a continental rift initiation phase, with distributed, relatively small-scale faults. This contrasts with the Gulf of Suez Rift, where faulting continued to a more evolved fault localization phase, with block-bounding faults >25 km in length. Results suggest that future studies could quantify fault evolution from rift initiation to fault linkage to displacement localization, by studying the spatial variation in faulting from the northern Nile Delta, south–southeastwards to the Gulf of Suez Rift.     

An assessment of paleodepositional environment and maturity of organic matter in sediments of the Setap Shale and Belait formations in West Sabah,East Malaysia by organic geochemical methods

The black shale samples collected from two Neogene formations in the Klias Peninsula area, West Sabah, have been assessed and characterized in details by gas chromatography, gas chromatography-mass spectrometry and a variety of organic geochemical parameters. The aims of this study are to describe the characteristics of organic matter of these sediments in terms of source/type of the organic matter, assess its thermal maturity and paleoenvironment of deposition, based primarily on biomarker distributions. The results of both formations do not reveal significant differences within the rock extracts. The gas chromatograms of the saturated hydrocarbon fractions of the Setap Shale and the Belait formations displayed monomodal n-alkane distributions and nearly identical regular sterane compositions with a predominance of C₂₇ regular steranes. These are consistent with open marine depositional environments dominated by marine biological matter. Another related feature of these rock extracts is the presence of a high relative abundance of gammacerane, indicating anoxic marine hypersaline source depositional environment. The relatively high abundance of common land plant-derived biomarkers, such as bicadinanes and oleananes, is a clear indication of a major terrigenous input to the source of the extractable organic matter. The predominance of oleanane biomarkers in both formations is indicative of angiospermis input and Tertiary source rocks. The high C₂₉/C₃₀ hopane ratios, moderate development of C₃₃–C₃₅ hopanes, high abundance of tricyclic terpanes and a slight predominance of C₂₇ regular sterane over C₂₈ and C₂₉ steranes are characteristic features tending to suggest a significant marine influence on these source rocks, thereby suggesting a mixed source input. The 22S/(22S+22R)C₃₂ hopane ratio has reached equilibrium, and this is supported by the high maturity level as indicated by the 22S/22SC_31–33 extended hopane ratios and 20S/(20S+20R)C₂₉ regular steranes ratios.     

Discovery of an ancient pharaoh’s temple on the Horus military road, Northern Sinai, Egypt

Detailed geophysical measurements have been carried out in the northwestern part of the Sinai Peninsula. This area was mainly used by the ancient Egyptian army forces to support the trading and mining trips to Sinai and Asia. The geophysical field work aimed to discover new buried archeological remains using the efficient archeogeophysical detailed and nondestructive methods including total magnetic field, vertical magnetic gradient, and very-low-frequency electromagnetic measurements. Results of the field geophysical measurements have led to a discovery of a temple which is located on the Horus military road. This discovery has been verified by an excavation program, under the supervision of the Supreme Council of Egyptian Antiquities, where buried remains of a pharaoh’s temple were detected and photographed. Some other sites were recommended for further excavation in the future.     

Analytical Behaviour of Bolt–Joint Intersection Under Lateral Loading Conditions

An analytical method is developed to provide a better understanding of bolt shearing across joint planes under lateral confinement. The study was undertaken in conjunction with a laboratory study of the double shearing of bolts in concrete. A review of various analytical methods is discussed, and the bending behaviour of the bolts is studied under both elastic and plastic conditions. Issues examined include; hinge point location, the effect of concrete strength on the bolt-bending behaviour; the influence of bolt axial loading and bolt diameter on the hinge point position with respect to sheared joint planes. It was found that the applied axial load on the bolt had a significant bearing on the location of the hinge points in different strength concrete, particularly at low strengths. The hinge point location is also influenced by the bolt diameter.     

Phenol and ammonium removal by using Fe-ZSM-5 synthesized by ammonium citrate iron source

Fe-ZSM-5 zeolites are important for many applications, especially for catalysis and volatile organic carbon removal. However, the inclusion of a high content of iron in the ZSM-5 structure is hindered due to the high pH required for hydrothermal synthesis. To overcome this problem, the synthesis of Fe-ZSM-5 zeolites with a novel iron chelate complex as the iron source (ammonium iron citrate) and a common iron source (iron chloride) was investigated. The synthesized materials were characterized by XRD, BET, SEM, FTIR, XPS and ICP. The total iron content was determined by ICP. Fe-ZSM-5 zeolites prepared by the ammonium iron citrate source method contain the highest iron concentration within the framework of a Mobil five structure, which has a high surface area and crystallinity. The prepared materials were used to remove phenol and ammonium. The catalytic results demonstrated that Fe-ZSM-5 prepared with ammonium iron citrate is the best catalyst.     

大兴安岭北部塔河堆晶辉长岩体的形成时代、地球化学特征及其成因

本文系统地报道了大兴安岭北部塔河辉长岩的主量元素、微量元素和锆石Hf同位素特征,重点讨论了塔河堆晶辉长岩体的岩石成因、原始岩浆的源区特征及其地质意义。研究结果表明,塔河堆晶辉长岩体SiO2含量从42．5％到47．4％,平均为45．2％,Al2O3为15．9-32．9％,平均为23．6％,大于17％,CaO为11．7-17．1％,TiO2<0．5％,P2O5<0．1％,富集LILE, 亏损HFSE,这些地球化学特征类似于活动大陆边缘或岛弧环境的辉长岩。激光ICP-MS锆石年龄测定结果显示,塔河辉长岩形成于333±8 Ma前。负的εHf(t)值(-2--5)表明其源区为富集型岩石圈地幔或下地壳。因此,本文推测,塔河堆晶辉长岩来自于地幔辉石岩的部分熔融,该源区的形成可能与俯冲背景下流体交代作用有关,从而表明在330 Ma左右,该区存在过板块的消减作用,可能与松嫩和兴安地块拼合有关。     

Palaeoenvironmental reconstruction of a middle Miocene alluvial fan to cyclic shallow lacustrine depositional system in the Calatayud Basin (NE Spain)

ABSTRACT The middle Miocene sedimentary fill of the Calatayud Basin in north‐eastern Spain consists of proximal to distal alluvial fan‐floodplain and shallow lacustrine deposits. Four main facies groups characteristic of different sedimentary environments are recognized: (1) proximal and medial alluvial fan facies that comprise clast‐supported gravel and subordinate sandstone and mudstone, the latter exhibiting incipient pedogenic features; (2) distal alluvial fan facies, formed mainly of massive mudstone, carbonate‐rich palaeosols and local carbonate pond deposits; (3) lake margin facies, which show two distinct lithofacies associations depending on their distribution relative to the alluvial fan system, i.e. front (lithofacies A), comprising massive siliciclastic mudstone and tabular carbonates, or lateral (lithofacies B) showing laminated and/or massive siliciclastic mudstone alternating with tabular and/or laminated carbonate beds; and (4) mudflat–shallow lake facies showing a remarkable cyclical alternation of green‐grey and/or red siliciclastic mudstone units and white dolomitic carbonate beds. The cyclic mudflat–shallow lake succession, as exposed in the Orera composite section (OCS), is dominantly composed of small‐scale mudstone–carbonate/dolomite cycles. The mudstone intervals of the sedimentary cycles are interpreted as a result of sedimentation from suspension by distal sheet floods, the deposits evolving either under subaerial exposure or water‐saturated conditions, depending on their location on the lacustrine mudflat and on climate. The dolomite intervals accumulated during lake‐level highstands with Mg‐rich waters becoming increasingly concentrated. Lowstand to highstand lake‐level changes indicated by the mudstone/dolomite units of the small‐scale cycles reflect a climate control (from dry to wet conditions) on the sedimentation in the area. The spatial distribution of the different lithofacies implies that deposition of the small‐scale cycles took place in a low‐gradient, shallow lake basin located in an interfan zone. The development of the basin was constrained by gradual alluvial fan aggradation. Additional support for the palaeoenvironmental interpretation is derived from the isotopic compositions of carbonates from the various lithofacies that show a wide range of δ¹⁸O and δ¹³C values varying from ?7·9 to 3·0‰ PDB and from ?9·2 to ?1·7‰ PDB respectively. More negative δ¹⁸O and δ¹³C values are from carbonate‐rich palaeosols and lake‐margin carbonates, which extended in front of the alluvial fan systems, whereas more positive values correspond to dolomite beds deposited in the shallow lacustrine environment. The results show a clear trend of δ¹⁸O enrichment in the carbonates from lake margin to the centre of the shallow lake basin, thereby also demonstrating that the lake evolved under hydrologically closed conditions.     

影响三大洲的北非强沙尘暴动力机制WRF-chem模拟与分析北大核心

基于WRF-chem模式对北非2018年3月下旬的典型强沙尘暴过程进行模拟,分析了此次强沙尘发生季节、持续时间、局地特征以及传输路径的关键动力系统与动力机制。鉴于起沙是沙尘暴发生的关键点之一,并且起沙主要取决于风力和下垫面沙源性质,本文测试了三种起沙参数化方案的影响,并将模拟结果与卫星MODIS监测及其再分析资料MERRA-2进行了对比,又经系列统计方法检验。结果显示,宏观思路的起沙方案GOCART比AFWA和UoC两种起沙方案更适合此次大尺度强沙尘暴数值模拟(锋面跨度接近60个经度)。综合沙尘暴关键系统的动力机制分析和数值模拟结果显示,强沙尘暴关键系统为深厚的西风槽、沙尘冷锋锋面和锋后的地面高压反气旋。北非中部深厚的西风槽为后倾槽,该系统稳定,造成沙尘暴持续时间长。沙尘暴锋后反气旋中的下沉气流抑制了扬沙向高层扩散,造成低层能见度恶劣。沙尘锋区结合了动力、热动力以及湿热动力不稳定,因此锋区风力大,地面沙尘驱动力强。而西风槽和强大反气旋依托环流形势,提供了沙尘传输到三大洲的长途输送力。