NE Direction Research Articles

Assessment of Air Quality Around Gbaran – Ubie Gas Processing Plant, yenagoa, Bayelsa State, Southern Nigeria

This study determined the air quality status around Gbaran and its environs as a result of gas processing taking place in the area. The study characterized and quantified air pollutants emitted into the surrounding at two different seasons and also determined the seasonal variations in the concentration levels of gases in the air sample with a view to evaluating the air quality implication of the gas processing plant. Digital hand - held gas Analyzers were used to monitor air pollutants including; Total Suspended Particulate Matter (TSPM), Sulphur dioxide (SO 2 ), carbon monoxide (CO) and Volatile Organic Compounds (VOCs), while Kestrel Model NO. 4500 pocket weather tracker was used to monitor the meteorological parameters such as: ambient temperature, relative humidity, wind speed. The direction of wind was also detected using wind vane. The results of the study showed dominant wind direction during the wet season within the SE and the NE direction while during the dry season it was NW and NE. The maximum wind speed during the wet and dry seasons was 3.75m/s and 2.80m/s respectively. The Relative humidity values in wet season ranged between 82.40% - 98.80% while in the dry were between 37.15% - 74.95%. Temperature in the wet season ranged between 24.80 o C – 30.40 o C while during the dry season it was between 31.05 o C– 43.20 o C. The mean concentration of TSPM during the wet season ranged between 16.00µg/m 3 –2,423.50µg/m 3 while in the dry, it was between 508.00 µg/m 3 – 3,800.00 µg/m 3 . That of SO 2 during the wet season ranged between 0 ppm – 1 ppm while in the dry season it was between 0.50 ppm – 1.50 ppm. CO was emitted in the range of 0 .50ppm – 6.00 ppm in the wet season and 0.87 ppm – 2.00 ppm in the dry season. For VOCs, its mean concentration during the wet season ranged between 0.65 ppm – 3.25 ppm and 3.15 ppm – 10.00 ppm during the dry season. The study observed that the mean concentrations of gaseous pollutants in the dry season were higher than the wet season and were also found to exceed the limits recommended by Federal Ministry of Environment, except CO that was lower and below the set limit. The study therefore concluded that the Gbaran - Ubie gas processing plant is a source of air pollution in the area. Keywords: Assessment, Air quality, Gas processing plant, Gbaran – Ubie, Obunagha, Yenagoa DOI : 10.7176/JEES/9-7-03 Publication date :July 31 st 2019

LAVA DOME CHANGES DETECTION AT AGUNG MOUNTAIN DURING HIGH LEVEL OF VOLCANIC ACTIVITY USING UAV PHOTOGRAMMETRY

Abstract. Lava dome changes detection during increasingly high volcanic activity are essential for hazard assessment purposes. However, it is challenging to conduct direct field measurement due to safety reason. Here, we investigate the lava dome changes of Mount Agung in Indonesia during the highest level of volcanic activity. On 22 September 2017, the rumbling and seismic activity in this volcano started increasing to the highest level for a period of time. We afterwards collected image data at lava dome area by using UAV over this time period. To accomplish the goal of change detection, we assembled and developed a fixed-wing UAV platform, i.e. Buffalo FX-79 to acquire images of Mount Agung whose elevation is roughly 3,142 m above sea level. We acquired the UAV images on two dates, i.e. Oct 19 and Oct 21 of 2017. Due to an exclusion zone surround the volcano, we could only operate the UAV at 20 km distance from the crater. With these data set, we produced three-dimensional point clouds, high-resolution Digital Elevation Model and orthophoto by using Structure from Motion (SfM) and Multi View Stereo (SfM-MVS) technique with Photoscan Pro software. From orthophoto data, we found two fluid areas at the crater's surface in NE direction (4,375.9 sq-m) and SE direction (3,749.8 sq-m). We also detected a fumarole which emitted steam and gases in the eastern part that continued for several days. In order to reveal the changes in lava dome surface, we used DEM to create cross-section profile. After that, we applied cloud to cloud comparison (C2C) algorithm to calculate the difference of lava dome based on two data set of point clouds and compared it with interferometric result from Sentinel-1A data. The data from the Sentinel-1A satellite (15 Oct – 27 Oct 2017) were processed to obtain the interferogram image of Mount Agung. This research therefore demonstrates a potential method to detect lava dome changes during high level of volcanic activity with photogrammetric methods by using UAV images. Within only two days the data were successfully acquired. From the DEM data and cross-section profile between two data set, we noticed that no significant surface change was found around the lava dome surface. Moreover, we also found that there was no significant lava dome changes and vertical displacement during these two time periods as the point cloud comparison and distance result. The average of difference distance is 2.27 cm with a maximal and minimal displacement of 255 cm and 0.37 cm respectively. This result was then validated by using InSAR Sentinel that showed small displacement, i.e 6.88 cm. It indicated that UAV photogrammetry showed a good performance to detect surface changes in centimeter fraction.

Evaluation of the Local Geodetic Network in Jurmala City

In order to evaluate the accuracy of the local geodetic network of Jurmala City, in research, comparison of forty-seven selected polygonometry network point coordinates with the obtained data was made by performing measurements by real time cinematic (RTK) method in LatPos base station system. Points were chosen so in order to cover evenly the entire territory of the city. At present, gradual renewal and improvement of the local geodetic network takes place in Jurmala. The linear discrepancy of coordinates obtained in measurements varies from 0.016 m to 0.259 m, mean linear discrepancy in the measured points is fixed 0.110 m. Discrepancy of plane coordinates in different regions of Jurmala is not even. It is rather even within approximate boundaries of the determined regions, this is indicated by different directions of offset vectors, which in eastern part of the city are pointed mainly in NW direction, in central part directions are pointed in W direction, but in the western part of the city pointed in NE direction. Concerning heights, only for 3 of measured points discrepancy exceeds 0.05 m error and there are no connection concerning some specific region. 15% of the measured points of the local geodetic network are with appropriate accuracy of plane coordinates. The linear discrepancy of plane coordinates for points of the local geodetic network, which are measured by RTK method and compared with data from the improved network is 0.024 (m), which indicates the high accuracy of RTK method in measurement data. In Jurmala City, obtaining of data by GNNS data receivers is encumbered by large density of trees. Therefore the local geodetic network in city has very important role in order to ensure performance of geodetic measurements of high quality in the territory of the city. Aim of the research is to evaluate the accuracy of the local geodetic network of Jurmala City. The following tasks have been set for achieving the aim: research of the given problem, visit of the local geodetic network points, performing control measurements, data processing and analysis.

Evidence of multiple slip events on postglacial faults in northern Fennoscandia

An analysis of high-resolution LiDAR-based digital elevation models (DEMs), trenching of Quaternary deposits, diamond drilling and a structural analysis of the bedrock were conducted in order to characterise the geological structure and to derive full slip profiles of the Venejärvi–Jauhojärvi postglacial fault complex located in northern Finland. The Venejärvi-Jauhojärvi fault complex consists of 17 surface ruptures striking in a SW–NE direction, cutting through Late Weichselian till and traceable for a total distance of 29.9 km. Based on stratigraphical and structural analysis we show that the Naamivitikko fault segment, which is part of the Venejärvi–Jauhojärvi complex, hosted up to three distinct slip events and it is therefore argued that the prevailing single-rupture hypothesis of postglacial faults should be treated with caution. Based on the measured surface rupture dimensions, it is conservatively estimated that the maximum moment magnitude of the paleoseismic event that the complex hosted, ranged between Mw ≈ 5.8–8.4. If uncertainties in the scaling laws equating surface rupture dimensions to moment magnitudes are accounted for, a more realistic maximum moment magnitude range between Mw ≈ 5.8–7.6 is given.

Gaia-DR2 distance to the W3 Complex in the Perseus Arm

The Perseus Arm is the closest Galactic spiral arm from the Sun, offering an excellent opportunity to study in detail its stellar population. However, its distance has been controversial with discrepancies by a factor of two. Kinematic distances are in the range 3.9-4.2 kpc as compared to 1.9-2.3 kpc from spectrophotometric and trigonometric parallaxes, reinforcing previous claims that this arm exhibits peculiar velocities. We used the astrometric information of a sample of 31 OB stars from the star-forming W3 Complex to identify another 37 W3 members and to derive its distance from their Gaia-DR2 parallaxes with improved accuracy. The Gaia-DR2 distance to the W3 Complex,2.14$^{+0.08}_{-0.07}$ kpc, coincides with the previous stellar distances of $\sim$ 2 kpc. The Gaia-DR2 parallaxes tentatively show differential distances for different parts of the W3 Complex: W3 Main, located to the NE direction, is at 2.30$^{+0.19}_{-0.16}$ kpc, the W3 Cluster (IC 1795), in the central region of the complex, is at 2.17$^{+0.12}_{-0.11}$ kpc, and W3(OH) is at 2.00$^{+0.29}_{-0.23}$ kpc to the SW direction. The W3 Cluster is the oldest region, indicating that it triggered the formation of the other two star-forming regions located at the edges of an expanding shell around the cluster.

A Neoarchean K-rich granitoid belt in the northern North China Craton

The Archean metamorphic basement in the southeastern part of Eastern Hebei to Western Liaoning provinces, northern North China Craton, is dominated by Neoarchean K-rich granitoids, with a small amount of Neoarchean supracrustal rocks and Na-rich dioritic-tonalitic-trondhjemitic-granodioritic gneisses, and minor Paleo- to Mesoarchean rocks. The Paleo- to Mesoarchean lithological signatures include TTG gneisses and supracrustal rocks at the Caozhuang and Caochang areas. The Neoarchean K-rich granitoids form a ca. 350 km long belt extending in a NE direction, and primarily consist of porphyritic monzodioritic-quartz monzodioritic-granodioritic-monzogranitic (MQGM) gneisses and secondary monzogranite-syenogranites and charnockites, with minor Neoarchean TTG gneiss enclaves. Based on their major mafic mineral phases, the MQGM gneisses can be divided into an amphibole-dominated group and a biotite-dominated group. Zircon U-Pb isotopic dating reveals that the Caozhuang trondhjemitic gneisses, amphibole-dominated MQGM gneisses, and biotite-dominated MQGM gneisses were emplaced at ∼2.90 Ga, 2.55–2.53 Ga, and 2.55–2.53 Ga, respectively. The amphibole-dominated porphyritic MQGM gneisses are geochemically analogous to sanukitoids, and the sanukitoid magma was derived from the partial melting of lithospheric mantle metasomatized by dehydration fluids and melts from subducted slabs and related sediments, following the fractionation of amphibole and clinopyroxene during their magmatic evolution. The magmatic precursors of the biotite-dominated MQGM gneisses were most likely generated by the partial melting of medium- to high-K mafic-intermediate rocks and locally generated by the partial melting of metagreywackes at medium pressures. Within the K-rich granitoid belt, the 2.55–2.53 Ga porphyritic MQGM gneisses experienced 2.53–2.51 Ga E-W extension and strike-slip shearing deformation in the Jinzhou-Xingcheng structural domain, and diapiric upwelling by the formation of dome structures in the Jielingkou-Anziling-Suizhong structural domain. All these structures then suffered a top-to-the-SE-NEE thrusting in the northern margin during 2.51–2.50 Ga. The 2.53–2.51 Ga dioritic-tonalitic-trondhjemitic-granodioritic gneisses and charnockites in the Taipingzhai-Santunying-Zunhua structural domain firstly underwent diapiric upwelling during 2.51–2.50 Ga, then together with the 2.52–2.50 Ga volcanic-sedimentary rocks in the Shuangshanzi-Qian’an-Lulong structural domain overprinted by nearly N-S-striking dextral strike-slip shearing deformation during 2.50–1.80 Ga. The temporal-spatial relationships, petrogenesis, and structural patterns of these various Neoarchean lithological assemblages confirm that the Neoarchean K-rich granitoid belt in the northern North China Craton was most likely developed in an active continental margin setting, and our studies suggest this involved progressively southeastward multi-stage retreating oceanic slab subduction and collisions between an oceanic arc and an ancient continental nucleus.

Estimation of Vs Structure of Krueng Aceh and its Suburb Basin of Aceh Province, Indonesia, Derived from Microtremor Measurements

The Aceh and Seulimeum Faults flank the Krueng Aceh Basin in Indonesia, and the shear-wave velocity (Vs) structure of the basin is not extensively available. Understanding the Vs structure is very important in order to figure out how the basin structures seemingly appear, and this can eventually be used to generate a microzonation map for other forthcoming studies. To provide this, Vs was measured over an area approximately covering Banda Aceh City and its surroundings, by setting two lines consisting of eight points projected in the NW–SE and SW–NE orientations. This research aims to facilitate the approximation of the Vs structure characteristics of the Krueng Aceh Basin using the microtremor array method (MAM). Triangular configurations were set by deploying four seismometers following an M-station geometry for three different array sizes (i.e., 3, 10, and 30 m in distance). The data were then processed by utilizing the spatial autocorrelation (SPAC) technique. The result shows that the Vs structure generally dips down from SE to NW, and it gradually declines from SW to NE. The combination of these Vs structures tends to be oblique toward the SW–NE direction. This form may be affected by the Aceh Segment Fault which is more active than the Seulimeum Segment Fault. The average maximum penetration depth and Vs are 603 m and 947.5 m/s in the SE–NW orientation, and 650 m and 958 m/s in the SW–NE direction. Generally, the thickness of the strata is greater in the upstream area compared to the downstream area. Their composition consists of alluvium (A) at the uppermost layer and diluvium (D) at the underlying layers. Then, all of the identified strata are aged from the Pleistocene to Tertiary Pleistocene (Tp). These characteristics of the strata could potentially cause surface damages as a result of site effect responses when an earthquake is occurring.

Lithological mapping of Ogun State, Southwestern Nigeria, using aeroradiospectrometry

Airborne gamma-ray spectrometric has gained more recognition over decades, since it serves majorly as a geological mapping tool in most areas. This method utilizes the variation in the three primordial radionuclide concentrations, U, K and Th, to study the lithology of different bedrocks. It measures the earth surface natural radionuclides, which enhances the distribution of soil- and rock-type formations. Ogun State, the study area, is bounded by geographical coordinates of easting 3.0°–5.0° and northing 6.2°–7.8° of tropical rainforest region, Southwestern Nigeria. The present study aims at mapping the distribution of radioelements and delineates the anomalies associated with various interpreted radiometric lithological (IRL) units using the three radioelements U (ppm), Th (ppm), K (%) and the total count (TC) in Ur and their ratios, U/K, U/Th and Th/K. The dose rates were also considered in the study. The lithology was described in terms of three formations; basement, basement–sediment and sediment. With the aid of Geosoft software (Oasis montaj) and Golden Surfer 10 software, the contour map was obtained which showed the trend of distribution of radioelements alongside their ratios. The uranium migration index was also carried out to check the regions associated with uranium leaching. The result revealed that uranium is more concentrated in NW and partly NE directions of the study area. This may be due to the presence of shale and possibly phosphate-bearing rock and metamorphozised granitic rocks while thorium has the largest deposit due to quarry activity which is associated with blasting of rocks and deposition from dumpsites. The study also revealed that only 2 out of all the 47 IRL units, A1 and C4, which belong to basement and basement–sediment formations have their mean dose value to be 1.51 mSv/yr and 1.43 mSv/yr which are above the 1 mS/yr recommended limit.

Three-dimensional structural modeling of a low permeability reservoir in the Banqiao formation of the Maxi Oilfield

This paper presents a three-dimensional geological modeling method for low permeability reservoirs based on core, logging, seismic, and dynamic data. Matrix and fractures are two types of reservoir space. This method includes two-step modeling methods, and different methods are used to establish a matrix model and fracture model. As a low permeability reservoir, Maxi Oilfield has entered the high water cut stage, and developing a precise three-dimensional structural model that can reflect the spatial distribution of the reservoir is an urgent task. First, the gravity flow channel deposition was determined by core observations and the characteristics of gravity flow reservoirs are described. On this basis, a three-dimensional quantitative geological model of the matrix is established using the sequential indicator simulation. The ant-tracking technique is used to identify the fracture development in Maxi Oilfield, and two groups of fractures, 50°–100° in an NE direction and 30°–35° in an NE direction, are identified as the main reservoirs. The discrete fracture distribution model is established deterministically, and then, the fracture model is modified by the distribution of fractures reflected comprehensively by the water flooding front, microseismic, and dynamic data. This three-dimensional structural model can guide the development of water injection wells in Maxi Oilfield.

Study on clues for gold prospecting in the Maizijing-Shulonggou area, Ningxia Hui autonomous region, China, using ALI, ASTER and WorldView-2 imagery

Several gold occurrences have been discovered in the Maizijing-Shulonggou area, Ningxia Hui autonomous region, China. The clues for gold prospecting in this area may relate to fractures and hydrothermal alterations, but it is very difficult to conduct a field investigation on the clues because of the alpine valleys. To explore the clues for gold prospecting, this study extracted geological information related to fracture zones and hydrothermal alterations using ALI, ASTER, and WorldView-2 data, and subsequently, explored potential relationships between extracted geological characteristics and gold mineralization. The WorldView-2 image in the study area was used for fracture interpretation. The azimuth and density of linear fractures were investigated, and the results showed that linear fractures with NE direction were most common, the gold occurrences except Au2 were all located in NE fracture zones, and all gold occurrences located in high fracture density areas (level 1–3 areas) where NE and NW fractures were the most common observations. This suggests that the high fracture density and NE and NW fractures are important indicators of potential gold mineralization. Hydrothermal alteration minerals in exposed bedrocks were mapped using ALI and ASTER imagery. Based on the spectral analysis, ASTER image in the study area were used to map quartz, illite and chlorite, while ALI image were used to map limonite. The spatial distribution of alteration minerals revealed regional specific alteration mineral in gold mineralization. In the northern Maizijing region, the composition of alteration mineral in the surrounding of Au1 was overwhelmed by quartz, while the alteration minerals in the surrounding of Au2-4 were dominated by limonite in the southern Shulonggou region, which showed different indicator minerals for gold prospecting in the two regions. As a result, the key areas for prospecting are the NE and NW fracture zones with quartz veins in the Maizijing region and the NE and NW fracture zones with limonitization in the Shulonggou region. In the Shulonggou region, pyrite in buried quartz-pyritization belt and illitization-pyritization belt is likely to be the precursor of limonite. Heavy mineral assemblages were analyzed for native gold content, and the results suggested high native gold content in the illitization-pyritization belt, followed by quartz-pyritization belt, which was consistent with the strong association of limonite and gold mineralization, thus the two belts shall be prioritized for gold prospecting in the Shulonggou region.

Análise dos fluxos nos aquíferos cárstico-fissurais da região da APA Carste de Lagoa Santa, MG

A área de estudos, que engloba a Área de Proteção Ambiental (APA) Carste de Lagoa Santa, se estende por 504 km2. Nesta região, ocorrem os metacalcários da Formação Sete Lagoas, composta pelos membros Pedro Leopoldo e Lagoa Santa, os quais acomodam os aquíferos cárstico-fissurais. O método de estudo envolveu o levantamento de estruturas rúpteis e de dissolução cárstica em uma malha de 9.000 m2, escala 1:300.000, com a finalidade de analisá-las e associá-las com as direções de cavernas e com direções de fluxos da água subterrânea comprovadas por testes de traçadores corantes (E-W, NE e SE), de sentido oriental. Por toda a área, a preponderância sistemática de cavernas e paleocondutos reliquiares na direção N70-90W, com caimento suave para leste, indica que esses paleocondutos resultam da dissolução ao longo da interseção das fraturas E-W, de alto ângulo, com o plano de acamamento suave, de direção NNW. Fraturas de alto ângulo de direção NE e SE também são frequentes, contudo, são raras as exposições dos paleocondutos e cavernas correlatos. Em contrapartida, embora as cavernas N-S se destaquem como mais persistentes e alongadas, assim como as E-W, não se observaram fluxos de água naquela direção (N-S). Os resultados demonstram que os parâmetros estruturais primordiais, as fraturas de alto ângulo e o acamamento, condicionam os fluxos subsuperficiais em condutos de cavernas ainda ativos no sentido oriental. No entanto, não se descarta a possibilidade de ocorrerem circulações profundas em segmentos N-S não observáveis nas zonas superiores.

Characteristics and evaluation of Mesozoic source rocks in the southeastern East China Sea continental shelf

ABSTRACT Source rocks are the material basis of oil and gas generation and determine the potential resources of exploration blocks and have important research value. This paper studies the lithology, thickness, and geochemistry of Mesozoic source rocks in the southeastern East China Sea continental shelf. The results show that the Mesozoic source rocks are mainly dark mudstone and coal-bearing strata. The total thickness of Lower–Middle Jurassic source rocks ranges from 100 m to 700 m, and that of Lower Cretaceous source rocks ranges from 50 m to 350 m. The overall thickness of Mesozoic source rocks is distributed in the NE direction and their thickness center is located in the Jilong Depression. The Lower–Middle Jurassic source rocks are mainly developed shallow marine dark mudstone and transitional coal measure strata. Those of the Lower Cretaceous are mainly mudstone of a fan delta front. Lower–Middle Jurassic and Lower Cretaceous hydrocarbon source rocks are dominated by type III kerogen, with Lower–Middle Jurassic hydrocarbon source rocks having high organic matter abundance and being medium–good hydrocarbon source rocks, while Lower Cretaceous hydrocarbon source rocks have relatively poor quality. From northwest to southeast, the vitrinite reflectance Ro of Mesozoic source rocks increases gradually. Source rocks in the study area are divided into three types. The first hydrocarbon-generating area is mainly located in the southeastern region of the study area, and the Jilong Depression is the hydrocarbon-generating center. The results of this study can provide a basis for exploration of Mesozoic oil and gas resources in the southeastern East China Sea continental shelf. © 2019 China Geology Editorial Office.

Research on optimization of development technology policy for low-permeability and low-pressure reservoir in Yangbaishan Block

There are poor physical properties and insufficient natural energy in the low-permeability and low-pressure reservoir of the Yangbaishan Block. Early this reservoir was mined by natural energy with a serious producing energy deficit. Subsequently, it was developed with mild water injection. During the water injection development, water quickly slid into the oil well along the crack, oil production decreased sharply and water content increased rapidly in the oil well, the water flooded well and the ineffective well gradually increased. Therefore, based on the reservoir geological characteristics, principle of injection and production balance is used to optimize reasonably for the development technology policy. Research indicates that the square inverted nine spot flooding pattern is recommended with a reasonable injection well direction of NE 72°and technical well spacing of 150 m. Reasonable injection-production ratio should be 2.16, reasonable technical well pattern density is 23 wells per square kilometer, and the average daily water injection rate of single well should be 11 m3. When injection-production system and injection proration are improved, water drive controlled degree is expected to increase by 16 %. This research can provide reference for the efficient development and safety management of other similar reservoirs.

Aeromagnetic data for mapping geologic contacts at Samr El-Qaa area, North Eastern Desert, Egypt

Delineating the edges of different magnetized sources represents a fundamental tool for interpreting and mapping rock boundaries of magnetic data. The present study deals with the enhancement of reduced to the pole map (RTP) of Samr El-Qaa area, North Eastern Desert, Egypt, to map deep and surface geologic contacts. The edge detection of geologic contacts is ensured by the upward continuation of reduced to the pole data at an altitude of 3 km, followed by the calculation of theta derivative and horizontal tilt angle derivative (HTAD) for RTP and upward continuation (3 km). The results obtained from the application of these techniques showed that the theta derivative delineates RTP source edges well, but the response of deeper sources is diffused. While HTAD presented well, responds to shallow and deep sources and also the edges of the sources were delineated well. HTAD showed a much sharper gradient over the edges of the magnetized sources at Samr El-Qaa area. The interpreted structural trends derived from shallow and deep Theta and HTAD maps of Samr El-Qaa territory illustrated that the most shallow dominant trends are NNE, NE, N-S, NNW, WNW, E-W and NW directions. While the deep structural ones are the ENE, NW, N-S, and E-W directions. This approach for edge detection used in this study is comprehensively applicable to other portions of the Egyptian Eastern Desert and other areas with alike geologic conditions around the world to give much sharper gradient over the edges of the magnetized sources which can be used for mineral and oil/gas exploration.

ACTIVE TECTONIC AND PALEOSEISMOLOGIC CHARACTERISTICS OF THE YENİCE-GÖNEN FAULT, NW TURKEY, IN LIGHT OF THE 18 MARCH 1953 YENİCE-GÖNEN EARTHQUAKE (Ms=7.2)

The Yenice-Gönen Fault (YGF) is located in the central part of the Biga Peninsula between Gönen and Yenice and is a right-lateral strike-slip active fault with general trending N65°E. On 18 March 1953 there was an earthquake on the YGF that died 263 people (Ms=7.2) and a 70 km surface rupture developed during this earthquake. In this study measurements of slip distribution were performed on the surface rupture of the Yenice-Gönen Earthquake (YGE) and the annual slip rate on the YGF was calculated. Right-lateral displacements of between 1.70±0.1 and 3.20±0.2 metres were measured on the surface rupture of the YGE. The maximum displacements were in an area close to the central part of the YGF (between Çakır and Karaköy village) and these values decreased relatively in NE and SW directions, documenting that was the bilaterally surface rupture propogation during the YGE. In the last 300.000 years, a total offset of 800±50 metres was measured on Gönen River and annual slip rate of 2.65±0.15 mm was calculated along the YGF. Current GPS studies show right-lateral strike-slip faults in the South Marmara region have slip rates of 6-8 mm/year. This slip rate is assessed as being partitioned between the YGF, Sarıköy Fault and Çan-Biga Fault zones which represent extensions of the North Anatolian Fault system within the South Marmara region. Paleoseismology studies determined that in the last 6200 years 6 earthquakes resulting in surface ruptures have occurred on the YGF, including the 1953 earthquake. According to the 14C and OSL dating results, the variable and irregular earthquake recurrence interval of YGF is ranging from 505 to 1793 years. In this study average earthquake recurrence interval of YGF was determined as 1180 years.

Fault characteristics and control on hydrocarbon accumulation of middle-shallow layers in the slope zone of Mahu sag, Junggar Basin, NW China

Abstract The development, evolution and formation mechanism of faults and their control on the migration and accumulation of Mesozoic oil and gas in the middle-shallow layers of the slope zone of Mahu sag were studied by the interpretation of seismic and drilling data. Two types of faults, normal and strike-slip, are developed in the middle-shallow layers of the slope zone of the Mahu sag and they are mostly active in the Yanshanian period. They are divided into four grade faults: The grade I strike-slip faults with NWW to near EW direction are related to the left-lateral transpressive fault zones in the northwest of Junggar Basin since the end of the Triassic. The grade II faults with NE to NNE direction are the normal faults located at the junction of the fault zone and the slope zone, and their formation is related to the extension at the top of the nose-like structures in the fault zone. The grade III faults, which are also the normal faults, are the result of the extension at the top of the lower uplifts in the slope zone and differential compaction. The grade IV faults with NE direction are normal faults, which may be related to the extension environment at the tip of the lower uplifts. Faults not only are the channel for the vertical migration of oil and gas, but also control the oil-gas accumulation. There are two types of oil-gas reservoirs in the middle-shallow layers of slope zone of Mahu sag: fault block reservoirs and fault-lithologic reservoirs. They have large traps and promising exploration potential.

Precipitation Concentration in Bangladesh over Different Temporal Periods

Precipitation concentration is an important component of climate, and an unbalanced distribution of precipitation can yield excess or scarcity of water resources, which in turn can influence plant growth, flood risk, and water resource use. The precipitation concentration index (PCI) is a well-known indicator for the measurement of temporal precipitation in a short or long area. The purpose of this study was to analyze precipitation concentration rates in different regions of Bangladesh using the precipitation concentration index (PCI) and the inverse distance weighting method. In this study, the rainfall data from 30 meteorological observatory stations across Bangladesh were collected for the period 1980 to 2011. We defined periods of varying lengths (i.e., annual, supraseasonal, seasonal, and three- and two-month rainfall concentrations) and compared their PCI values. The results showed that precipitation concentrations were mostly irregular when rainfall was concentrated within two to four months of the year. Higher PCI values were mainly identified in the eastern region and have strong seasonal influences, whereas lower PCI values were mostly observed in the northern region. The analyses of periodic variation and precipitation in Bangladesh generally follow through the SW–NE direction due to the summer monsoon, while during the winter monsoon, they follow the N–S direction where JAS and JFM showed higher and lower PCI values. We observed variations in PCI among different regions using the Kruskal–Wallis test of the mean PCI on a decadal scale (1980–1989, 1990–1999, and 2000–2011). The result showed that significant changes in the precipitation occurred during the period of 1980–2011. At a two-month scale, significant changes were identified during transition periods where PCI values were lower from 2000 to 2011 than those in the earlier decades.

Методические аспекты прогноза и поисков крупнообъемных золоторудных месторождений на примере Енисейского кряжа

Актуальность исследования обусловлена необходимостью изучения и вовлечения в производство новых крупнообъемных золоторудных месторождений, что будет способствовать образованию и долгосрочному развитию целых регионов РФ. Важным аспектом является разработка новых и совершенствование существующих методов поисков золоторудных месторождений. Целью исследования является апробация методики поисков золоторудных месторождений в сложных горно-таежных ландшафтах применительно к условиям Енисейского кряжа, в частности, в пределах малоизученной восточной части этого региона, а также выделение прогнозно-поисковых критериев и признаков вновь выявленного рудопроявления Буреминское и их сопоставление с критериями и признаками известного крупнообъемного золото-сульфидного Олимпиаднинского месторождения. Методы исследования: анализ литературных и фондовых данных; прогнозные построения на предмет выделения перспективных поисковых участков на выявление крупнообъемного золотого оруденения; разработка новых и совершенствование существующих методов и методических приемов поисков золоторудных месторождений; применение этих методов (литохимическое опробование по вторичным ореолам рассеяния разных уровней разреза элювиально-делювиальных отложений, шлиховое и сколковое (точечное) опробование) на практике; лабораторно-аналитические исследования - полуколичественный спектральный анализ на 26 элементов, химико-спектральный анализ на золото. Результаты. Вновь выявлена рудоконтролирующая зона складчато-разрывных деформаций рудопроявления Буреминское, приуроченная к зоне разрывных нарушений северо-северо-западной ориентировки, оперяющих к Ишимбинской системе разломов, в узле их сочленения с разрывами СВ направления. Комплекс шлихового и литохимического по вторичным ореолам рассеяния опробования надкоренного информативного малосмещенного горизонта элювиально-делювиальных отложений позволил выявить в пределах зоны рассланцевания несколько золотоносных минерализованных зон. Последние представляют собой зоны-залежи рассеянной вкрапленной золото-сульфидной минерализации, локализованные в интенсивно железо-магнезиально-карбонатизированных углеродсодержащих карбонат-кварц-серицитовых сланцах удерейской свиты сухопитской серии среднего рифея. Для золотой минерализации рудопроявления Буреминское выделены прогнозно-поисковые критерии и признаки. По ряду из них наиболее близким аналогом рудопроявления являются первичные вкрапленные золото-сульфидные руды Олимпиаднинского месторождения, с которым проведено сопоставление основных геологических элементов рудопроявления Буреминское.

Strike-slip faults and their significance for hydrocarbon accumulation in Gaoshiti–Moxi area, Sichuan Basin, SW China

Abstract Based on the three dimensional seismic data and drilling data in Gaoshiti–Moxi area, the structural characteristics and evolution process of strike-slip faults in the study area and their significance for gas accumulation were examined using the method of fault structure analysis. The results show that: (1) Transtensional strike-slip faults are developed in the Paleozoic in study area. On the profile, there are three types of structural styles: steep and erect, flower structures, “Y” and reversed “Y” type faults. On the plane, strike-slip faults developed in the Cambrian extending linearly and along the nearly EW, NW and NE direction. The faults are composed of multiple secondary faults in en-echelon arrangement; faults in the Permian are mainly along nearly EW and NW direction, and the Permian faults are distributed in the middle east part of the study area and they are more in the north than in the south. (2) The nearly EW and NW trending faults are dextral strike-slip faults, and the NE trending faults are sinistral strike-slip faults. The strike-slip strength of the nearly EW trending faults are the strongest and the maximum horizontal displacement is 550 m, while the strike-slip strength of the NE trending faults is the weakest. The Cambrian faults had stronger activities than the Permian faults. (3) The transtensional strike-slip faults were active in two periods, the early Caledonian period and the late Hercynian period, and were the products of oblique extension of pre-existing weak zones in Xingkai and Emei taphrogenesis, with certain inheritance in the main faults. (4) The strike-slip faults and surrounding fractures enhance the porosity and permeability of the reservoir in Cambrian Longwangmiao Formation and control the distribution of karst reservoirs in the Permian Qixia Formation–Maokou Formation, bringing about the situation of multiple gases bearing series in this area.

A close look at the well-known Seyfert galaxy: extended emission filaments in Mrk 6

Using various techniques of optical observations at the 6-m Russian telescope (emission-line images, long-slit and 3D spectroscopy), we have studied large-scale morphology and kinematics of the ionized gas in the Seyfert galaxy Mrk6. Having a significantly deeper images and spectra than those in previous works, we have not only mapped the ionized gas in the stellar disc but also found a system of faint filaments elongated in the NE direction up to a projected distance of 40 kpc (4.3R$_{25}$). Kinematics as well as an ionization state of the filament gas suggest the scenario that hard radiation of the active nucleus illuminated the matter accreted from outside and orbiting almost orthogonally to the Mrk 6 stellar disc. A possible source of gas accretion is still unknown, a deep image taken with the 1-m Byrakan Schmidt telescope does not show any stellar counterparts at the level of 27-28 mag/arcsec$^2$.