A Kinematic Model of the Formation of the Sim Trough of the Uralian Foredeep

The structural features and mechanism of the formation of the Sim trough within the Uralian Foredeep, as well as the development of the entire Karatau–Suleiman block, are considered. This wedge-shaped block was subject to lateral extrusion to the north along conjugated strike-slip fault zones under a general latitudinal compression. This factor determined the local meridional compression and latitudinal extension of the block. In the central part of the block, the latitudinal extension was compensated by gradual subsidence, which resulted in the formation of the Sim trough.     

Convergence acceleration of iterative sequences for equilibrium chemistry computations

Computational Geosciences - The modeling of thermodynamic equilibria leads to complex nonlinear chemical systems which are often solved with the Newton-Raphson method. But this resolution can lead...     

Models of the REE distribution in the black shale Bazhenov Formation of the West Siberian marine basin,Russia

Rare-earth elements abundance in black shales of the Upper Jurassic (Tithonian Stage)–Lower Cretaceous (Berriassian Stage) Bazhenov Formation is discussed. This formation is the principal oil source rocks of West Siberia. The deposits within the formation can be subdivided into two main marine groups: (a) moderately hemipelagic deposits (clayey-siliceous, including phosphatic and carbonate rocks) and low-density distal clayey turbidites (argillites), both are considered as normal and (b) silty argillites and clayey-silt rocks, which are channel deposits and considered as anomalous. The hemipelagic rocks of normal sections, which are enriched in the rare-earth elements (REE), accumulated under both slow rates of sedimentation (clayey-siliceous rocks) and faster rates of sedimentation (argillites). The channel deposits of anomalous sections, which are impoverished in the REE, accumulated exclusively under fast rates of sedimentation.Within the hemipelagic group the rate of sedimentation of the argillites was faster than of the clayey-siliceous rocks, but the REE concentration in the former rocks (140.4 ppm) is higher than in the latter group (97.4 ppm). The argillites are more than twice enriched in clayey material than clayey-siliceous rocks. It is likely that the clay fraction was the main carrier of REE in these rocks. In the channel group of rocks, the REE abundance in clayey-silt rocks (21.2 ppm) is lower than in the silty argillite (84.6 ppm), in which the clay content is elevated.With respect to redox potential the Bazhenov Formation rocks can be subdivided further into three groups, based on the degree of pyritization index (DOP): (1) the highly reducing clayey-siliceous rocks of normal sections, with high DOP; (2) the substantially reducing argillites and carbonate rocks of normal sections, with intermediate DOP; (3) the moderately reducing rocks of anomalous sections with low DOP. The rocks with the high DOP (group 1) are characterized by ΣLREE/Σ(M+H)REE ratios between 7.37 and 7.5, whereas the rocks with the lower DOP (group 2 and 3) are characterized by ΣLREE/Σ(M+H)REE ratios between 12.8 and 13.5. Negative Ce anomalies are either small or absent in all deposits, which is typical for reducing conditions.Thus, the Bazhenov Formation exemplifies the complex depositional conditions that influence the REE concentration in black shale. However, it is this very complexity that has contributed to the development of six separate depositional models (REE contents in ppm are given in brackets). (1) Phosphatic clayey-siliceous rocks of normal sections (367.95); (2) argillites of normal sections (130.73); (3) clayey-siliceous rocks of normal sections (85.97); (4) carbonate rocks, largely dolomites of normal sections (23.23); (5) silty argillites of anomalous sections (78.7) and (6) clayey-silt rocks of anomalous sections (19.66).     

Prediction of Engineering Properties of Basalt Rock in Jordan Using Ultrasonic Pulse Velocity Test

Basalt is an extrusive igneous rock derived from Lava and spread over different localities in Jordan. It can be used in industrial applications, and as construction materials. Before using basalt, it is essential to determine its dry density, porosity, uniaxial compressive strength, and Brazilian tensile strength. The testing procedure and sample preparation used to determine the engineering properties are time-consuming and need expertise. Hence, the ultrasonic pulse velocity (UPV) test, a quick and non-destructive evaluation method, was used to determine the engineering properties. Empirical relationships for determination of dry density, porosity, uniaxial compressive strength, Brazilian tensile strength, and tangent modulus of elasticity were deduced. Good correlation coefficients (R²?=?0.832–0.929) were obtained between UPV and dry density, porosity, uniaxial compressive strength, Brazilian tensile strength and modulus of elasticity. These correlations were limited to intact basalt with UPV?≥?4000 m/s.     

英国约克郡( Yo rkshire Dale)国家公园钙华苔藓植物群落研究

报道英国约克郡国家公园5个钙华沉积地点苔藓植物群落调查结果。该区域钙华苔藓群落共13个,由12科15属18种组成。区系地理成分由北温带和世界广布两种成分组成;生活型以垫状矮丛集型和交织型占优势。根据钙华沉积环境特征,划分Cron钙华苔藓群落、洞穴钙华苔藓群落、瀑华苔藓群落、峭壁钙华苔藓群落和泉华苔藓群落等5种类型。调查结果表明,研究区现代苔藓植物群落钙华沉积作用十分显著。      

Inverted basin analysis and geological modeling, Razzak Oil Field, Western Desert, Egypt

This paper deals with a geological modeling based on seismic and well data of the Razzak Oil Field, located in northwestern desert of Egypt aimed mainly at improving the knowledge on inversion tectonics in the sedimentary basin corresponding to the oil field. Contour maps of significant seismic horizons corresponding to the top of Meso-Cenozoic formations which represent the stratigraphic traps of the oil field (top Apollonia, top Abu Roash “G,” top Bahariya, and top Alamein) are presented. The final model consists of geological cross-sections showing the inversion basin in the Razzak Oil Field. From the seismic data interpretation and modeling, we have different results matching with regional tectonic and transcurrent motion model. There are two main fault trends: the first one was northeast–southwest matching the Jurassic rift where the Jurassic is characterized by normal faults that formed in conjunction with the opening of the Neo-Tethys, and the other fault trend is northwest–southeast matching with Cretaceous faults. This is followed by a period of compressive tectonism (Syrian Arc deformation) in which two of the Jurassic normal faulted blocks (one at the northern part and the other at the southern part of the Qattara–Alamein ridge in the Razzak field) are reactivated as reverse faulted by Eocene–Early Oligocene time.     

A new record and a new ichnospecies of Arachnostega from the Middle Miocene of Egypt

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.     

Shkol’noe gold deposit, the Russian Northeast

The Shkol’noe deposit is localized in a small granitoid stock, the root portion of which is traced using geophysical data to a depth of 5–8 km. The high-grade gold ore (33 gpt Au) is enriched in silver and principally differs in ore composition from the previously studied mesothermal gold-quartz and epithermal gold-silver deposits in the Russian Northeast. The main reserves of the Shkol’noe deposit concentrate in bonanzas (20% of the total volume of orebodies). The internal deformation is related to the rearrangement of matter in freibergite; exsolution structures in fahlore and native gold are related to postmineral metamorphism. It is suggested that the ore of the Shkol’noe deposit occupies a transitional position between porphyrytype and epithermal levels of ore deposition.     

Assessment of noise exposure and associated health risk in school environment

Noise exposure has become one of the most important factors in determining the quality of life in indoor environments. This paper assesses and analyzes noise exposure levels at school and preschool classrooms with different indoor environments. The sound level [A-weighting equivalent steady sound level L _Aeq (dBA)] was measured using a CEL-63× digital sound level meter. The noise level measurements were performed inside two preschools at three classrooms (an activity room, classroom KG1 and classroom KG2) and three schools at different classrooms, starting from grade 1 to grade 12. The logarithmic average noise levels (L _{Aeq avg}) and the 8-h average noise exposure level (L _{EX, 8-h}) were estimated for each classroom. Furthermore, health risk issues associated with the exposure to high noise levels were investigated using a questionnaire and an interview with more than 250 teachers at the preschools and the schools. Then, the results were analyzed using different statistical tools and were compared with the World Health Organization, Occupational Health and Safety and National Institute for Occupational Safety and Health standards. Also, the results were compared with those from different countries worldwide. The study results show that the 8-h average noise exposure level exceeded the allowable limits in some schools, which indicates that students and teachers can face a serious health effects from noise exposure. The comparisons show that the values of noise levels in Kuwait are higher than those in different countries. The maximum value of noise levels was found in secondary schools. The health problems found during the survey are potentially associated with issues related to hearing, voice, headache and the physiological function of teachers.