scholarly journals Characterizing Permeability from Geological and Geochemical Data in the Olkaria Domes Field in Kenya.

2021 ◽  
Vol 3 (1) ◽  
pp. 161-182
Author(s):  
Harriet Nkatha Achini ◽  
Olubunmi C Adeigbe ◽  
Bernard Kipsang Rop
Keyword(s):  
Research Work ◽  
Geothermal Gradient ◽  
Geothermal Field ◽  
Soil Gas ◽  
Geochemical Data ◽  
Rift System ◽  
Central Field ◽  
Ratio Distribution ◽  
North West ◽  
North East

Olkaria geothermal field is located in the Kenyan Rift Valley that is a part of the Great East Africa Rift System (EARS). The geothermal field continues to be associated with a high geothermal gradient that arises from shallow magmatic activities which are ongoing in the enormous igneous province. Exploration and drilling of wells that were undertaken in the past revealed the existence of exploitable geothermal steam. The Olkaria field is divided into seven sections namely; Olkaria East field, Olkaria North East field, Olkaria North West field, Olkaria South East field, Olkaria South West field, Olkaria Central field, and Olkaria Domes field. The productivity of the geothermal wells continues to be influenced by factors such as subsurface permeability. Permeability is one of the parameters used for the characterization of geothermal fields. Other parameters used for characterization are associated with geotechnical weak zones and include features such as; fractures, vein bodies, and deformational fault systems. The research work involved geoscientific characteristics of the Olkaria Domes field based on the geological and geochemical factors to characterize the permeability of the field. The research involved studying rock types in the area by analysing drill cuttings obtained from six drilled wells in the Olkaria Domes field. Three of the six drill wells were considered for correlative description for the purpose of this paper. Correlation of the main lithologies and zones for loss of circulation in the field was also undertaken as well as the creation of mineralogical maps to capture the distribution of the minerals that were derived from hydrothermal weathering processes. The depths and formation for major loss circulation zones in the reservoir section of the field were identified and included in the description. Analysis of soil gas survey using radon as a geochemical tool in the Domes field was also carried out successfully. The relatively high levels of the soil gas ratios that were analysed captured the ratio distribution of carbon dioxide to radon at various reservoir depths. The detection of the two gases at the surface showed the existence of permeable zones which facilitated the movement of the gases through the fault-controlled structural systems of the studied Olkaria Domes field.

The Chengwatana Volcanics, Wisconsin and Minnesota: petrogenesis of the southernmost volcanic rocks exposed in the Midcontinent rift

1997 ◽  
Vol 34 (4) ◽  
pp. 536-548 ◽  
Author(s):  
Karl R. Wirth ◽  
Zachary J. Naiman ◽  
Jeffrey D. Vervoort
Keyword(s):  
Trace Element ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Geothermal Gradient ◽  
Limited Range ◽  
Geochemical Data ◽  
Rift System ◽  
Midcontinent Rift ◽  
Element Abundances ◽  
Isotopic Compositions

The southernmost exposed rocks of the North American Midcontinent rift system (1100 Ma) consist of 3000 m of mafic volcanic flows and minor interflow sediment exposed along the St. Croix River in Minnesota and Wisconsin. The flows are mostly high-Fe tholeiitic basalt with plagioclase phenocrysts and ophitic to subophitic clinopyroxene. Abundant secondary chlorite, epidote, and actinolite indicate the group was metamorphosed to greenschist facies (~350 °C). Low sodium (M4 site) and tetrahedral aluminum (AlIV) contents of actinolite indicate low-pressure metamorphism (0.25 GPa) and imply a geothermal gradient of 45 – 50 °C/km. Low magnesium (Mg# = 0.37–0.58) and Ni contents (36–185 ppm) indicate the basalts have undergone significant fractionation and are not primary mantle melts. Incompatible element abundances are inversely correlated with Mg#, and most samples plot within either high or low trace element groups (e.g., Ti, P, Zr). The basalts are enriched in the light rare earth elements and Th, and are variably depleted in Ta and Nb relative to La and Th. Initial 143Nd/144Nd compositions of the group range from 0.51099 to 0.51122 (initial εNd = −4.5 to +0.1). Most flows have isotopic compositions within a relatively limited range (initial εNd = −2.5 to −1.6), but exhibit variable trace element abundances. Flows with the highest and lowest initial 143Nd/144Nd ratios have isotopic compositions that are inversely correlated with trace element abundances and ratios (e.g., La/Yb, Th/La, Th/Ta). The combined geochemical data suggest that the Chengwatana basalts originated from plume-derived melts and underwent variable fractional crystallization and crustal contamination. These melts may have interacted with lithospheric mantle enriched during Penokean subduction.

Investigation of Urban Environment Using Tasseled Cap Transformation

2020 ◽  
pp. 88-96
Author(s):  
Asraful Alam ◽  
Arijit Ghosh ◽  
Lakshminarayan Satpati
Keyword(s):  
Urban Environment ◽  
Research Work ◽  
World Population ◽  
North West ◽  
North East ◽  
The North ◽  
Tasseled Cap ◽  
Tasseled Cap Transformation ◽  
The Status ◽  
Urban Settlements

Urban settlements have more complex environments, in unremitting fruition, where most of the world population lives. Most of the cities in developing countries have been developed without a rationale, and the life conditions are repeatedly insufferable. For this research work, NDVI is particularly used to assess the status of vegetation cover. Tasseled cap is another index that creates three band images for this study. Brightness, greenness, wetness are the three bands that represent the area under consideration. The present study aims particularly at comparing high NDVI area and greenness values given by tasseled cap and low NDVI values and high brightness values and status of urban environment. Based on the overlapping of tasseled cap image, an NDVI image is observed in which most of the area of healthy vegetation is located in the north west and south east part of Kharagpur city, which extended from south west to north east and north to south respectively.

scholarly journals Thermo-mineral waters of Hammam Meskoutine (north-east Algeria): Composition and origin of mineralization

2017 ◽  
Vol 34 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Abdelwaheb Benamara ◽  
Houria Kherici-Bousnoubra ◽  
Fouzia Bouabdallah
Keyword(s):  
Saturation Index ◽  
Research Work ◽  
Chemical Study ◽  
Geothermal Gradient ◽  
Mineral Waters ◽  
Warm Up ◽  
North East ◽  
Eastern Algeria ◽  
Extreme North ◽  
Physical And Chemical

Abstract The extreme north-eastern Algeria, in particular the Guelma city conceals thermal springs, whose waters circulating at great depths allow the rain-waters to warm up (according to the average geothermal gradient of 1°C per 33 m) and to acquire a mineralization which depends on the traversed rock. The goal of this research work was to determine mineralization origin of the thermo-mineral waters of Hammam Meskoutine (Algerian N-E). A hydro-chemical study involved analyses of a number of physical and chemical parameters of waters such as: temperature, hydrogen potential, electrolytical conductivity, Cl-, SO4 2-, HCO3 -, Ca2+, Mg2+, K+ and Na+. The data processing on the diagram revealed two dominating chemical facies: sulphate-magnesium and bicarbonate magnesium. With a high conductivity in excess of 2300 μS·cm-1, the temperature reaches 97°C. Calculation of the saturation index shows that the waters are supersaturated in carbonate minerals (calcite, dolomite and aragonite) and less saturated with evaporite minerals (halite, anhydrite, sylvite and gypsum). The reconstitution in dissolved salts reveals a dominant salt rich in calcium bicarbonates, in calcium sulphates and secondarily in magnesium salts. Geological sections used in the study zone affirm that the chemical composition of the spring waters comes from the neritic limestone dissolution and the gypso-saline complex of Hammam Meskoutine.

scholarly journals Geological Formation Mechanism and Thermal Resources Assessment of Geothermal Spring in Lushan County, China

2020 ◽  
Vol 10 (2) ◽  
pp. 592 ◽  
Author(s):  
Qing Zhang ◽  
Zhaohui Bin ◽  
Yongji Xu ◽  
Shaohe Luo ◽  
Li Zhao ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Hot Springs ◽  
Clean Energy ◽  
Thermal Control ◽  
Field Investigation ◽  
Geothermal Field ◽  
Characteristic Structure ◽  
North West ◽  
North East ◽  
Development And Utilization

Geothermal resource is green and clean energy, and geothermal field is widely distributed in the world. Its development and utilization has little harm to the environment, can change the current situation of energy consumption mainly based on fossil energy, reduce carbon emissions, and promote the development of techniques for sustainable processing of natural resources. However, each geothermal field has its own characteristic structure, origin, and storage, so it is necessary to carry out targeted research. In this paper, the geothermal characteristics and geological characteristics of the geothermal belt in Lushan County, China are analyzed by means of remote sensing interpretation, field investigation and observation, geophysical exploration, long-term observation, pumping test, and hydrochemical analysis. Result of this study shows that the geothermal belt of Lushan geothermal fields is as a result of primary thermal control and heat conduction structures of the near east-west Checun-Xiatang deep fault as well as secondary thermal control and heat conduction structures of near north-east and north-west secondary faults; and annual recoverable geothermal energy of whole geothermal field is 4.41 × 1011 MJ. The research results will be beneficial for the development and utilization of Lushan hot springs. At the same time, it also provides reference for more geothermal research.

Multiphase oblique extension on the North West Shelf of Australia

2021 ◽  
Author(s):  
Chris Elders ◽  
Sara Moron
Keyword(s):  
Seismic Data ◽  
Lower Cretaceous ◽  
Passive Margin ◽  
Rift System ◽  
Active Deformation ◽  
North West ◽  
North East ◽  
The North ◽  
Northern Carnarvon Basin ◽  
Carnarvon Basin

<p>The North West Shelf of Australia has experienced numerous rift events during its prolonged evolution that most likely started in the Lower Palaeozoic and continued through to the formation of the present day passive margin in the Lower Cretaceous.  Carboniferous and Permian is associated with rifting of the Lhasa terrane, a phase extension in the Lower and Middle Jurassic associated with the separation of the Argo terrane Upper Jurassic to Lower Cretaceous extension culminated in the separation of Greater India and Australia.  Investigations based on interpretation of extensive, public domain seismic data, combined with numerical mechanical modelling, demonstrate that crustal structure, rheology and structural fabrics inherited from older events exert a significant control on the architecture of younger rifts.</p><p>Defining the older, more deeply buried rift episodes is challenging, but with seismic data that now images deeper structures more effectively, it is clear that NE-SW oriented Carboniferous to Permian aged rift structures control the overall geometry of the margin.  Variations in the timing, distribution and intensity of that rift may account for some of the complexity that governs the Triassic – a failed arm of the rift system might account for the accumulation of thick sequences of fluvio-delatic sediments in an apparent post-rift setting, while active deformation and igneous activity continued elsewhere on the margin.</p><p>A renewed phase of extension began in the latest Triassic in the western part of the Northern Carnarvon Basin, but became progressively younger to the NE.  High-resolution mechanical numerical experiments show that the dual mode of extension that characterises the Northern Carnarvon Basin, where both distributed and localised deformation occurs at the same time, is best explained by necking and boudinage of strong lower crust, inherited form the Permian rift event, proximal to the continental margin, and a subdued extensional strain rate across the distal extended margin.  A very clear and consistent pattern of ENE oriented extension, which interacts obliquely with the older NE-SW oriented Permian aged structures, is apparent across the whole of the Northern Carnarvon Basin and extends north east into the Roebuck and Browse Basins.  This is at odds with the NW-SE oriented extension predicted by the separation of the Argo terrane which occurs at this time.  This may be explained by the detached style of deformation that characterises the Mesozoic interval.  Alternatively, the separation of Greater India may have exerted a stronger influence on the evolution of the margin during the Jurassic than hitherto recognised.</p>

Employment Pattern and Extent of Under-utilisation of Manpower in Rural Baran; Areas of Pakistan

1993 ◽  
Vol 32 (4II) ◽  
pp. 1225-1233
Author(s):  
Sabur Ghayur
Keyword(s):  
Crop Production ◽  
Labour Force ◽  
Research Work ◽  
Labour Force Participation ◽  
Hydroelectric Power ◽  
Economic Activities ◽  
North West ◽  
North West Frontier Province ◽  
Physical Infrastructure ◽  
Employment Pattern

The barani (rain-fed) region accounts for about a fifth of the cultivated area in Pakistan. It has the potential to significantly increase crop production levels. Similarly, considerable scope exists in this area for the development of forests, fruit and vegetable gardening, pasture and stock rearing. Most of the natural resources are also found in this tract. Its hilly areas possess a vast potential for tourism. Besides, significant opportunities exist for irrigation and hydroelectric power generation. An optimum utilisation of all this potential, obviously, is employmentgenerating and income-augmenting. Despite all such realisations this region as a whole, unfortunately, is identified as the least attended to area in terms of provision of socio-physical infrastructure, other development programmes and, even, research work. This led to a deterioration of the employment situation in the barani region as a whole. A poor information base and analysis thereof on employment and manpower related variables is also the consequence of such a treatment to this area. I This paper, using the data of a field survey, tries to fill, though partly, the vacuum on employment and related variables in the rural barani region. An attempt is made here to record and analyse the labour force participation rates, employment pattern (main economic activities) and unemployment/underemployment levels prevailing in the rural baran; areas of the provinces of the Punjab and North-West Frontier Province (NWFP).

A new volcanic province: evidence from glacial erratics in western North Greenland

2000 ◽  
pp. 35-41 ◽  
Author(s):  
Peter R. Dawes ◽  
Bjørn Thomassen ◽  
T.I. Hauge Andersson
Keyword(s):  
Volcanic Rocks ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Common Component ◽  
Volcanic Province ◽  
North West ◽  
North East ◽  
The North ◽  
Surficial Deposits ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Dawes, P. R., Thomassen, B., & Andersson, T. H. (2000). A new volcanic province: evidence from glacial erratics in western North Greenland. Geology of Greenland Survey Bulletin, 186, 35-41. https://doi.org/10.34194/ggub.v186.5213 _______________ Mapping and regional geological studies in northern Greenland were carried out during the project Kane Basin 1999 (see Dawes et al. 2000, this volume). During ore geological studies in Washington Land by one of us (B.T.), finds of erratics of banded iron formation (BIF) directed special attention to the till, glaciofluvial and fluvial sediments. This led to the discovery that in certain parts of Daugaard-Jensen Land and Washington Land volcanic rocks form a common component of the surficial deposits, with particularly colourful, red porphyries catching the eye. The presence of BIF is interesting but not altogether unexpected since BIF erratics have been reported from southern Hall Land just to the north-east (Kelly & Bennike 1992) and such rocks crop out in the Precambrian shield of North-West Greenland to the south (Fig. 1; Dawes 1991). On the other hand, the presence of volcanic erratics was unexpected and stimulated the work reported on here.

Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland

1999 ◽  
pp. 65-78
Author(s):  
Henrik Rasmussen ◽  
Lars Frimodt Pedersen
Keyword(s):  
Tectonic Setting ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
West Greenland ◽  
North West ◽  
North East ◽  
Metavolcanic Rocks ◽  
Arc Setting ◽  
Area North ◽  
Back Arc

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Frimodt Pedersen, L. (1999). Stratigraphy, structure and geochemistry of Archaean supracrustal rocks from Oqaatsut and Naajaat Qaqqaat, north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 65-78. https://doi.org/10.34194/ggub.v181.5114 _______________ Two Archaean supracrustal sequences in the area north-east of Disko Bugt, c. 1950 and c. 800 m in thickness, are dominated by pelitic and semipelitic mica schists, interlayered with basic metavolcanic rocks. A polymict conglomerate occurs locally at the base of one of the sequences. One of the supracrustal sequences has undergone four phases of deformation; the other three phases. In both sequences an early phase, now represented by isoclinal folds, was followed by north-west-directed thrusting. A penetrative deformation represented by upright to steeply inclined folds is only recognised in one of the sequences. Steep, brittle N–S and NW–SE striking faults transect all rock units including late stage dolerites and lamprophyres. Investigation of major- and trace-element geochemistry based on discrimination diagrams for tectonic setting suggests that both metasediments and metavolcanic rocks were deposited in an environment similar to a modern back-arc setting.

ON SHALLOW‐HOLE TEMPERATURE MEASUREMENTS—A TEST STUDY IN THE SALTON SEA GEOTHERMAL FIELD

Geophysics ◽  
1977 ◽  
Vol 42 (3) ◽  
pp. 572-583 ◽  
Author(s):  
Tien‐Chang Lee
Keyword(s):  
Numerical Methods ◽  
Ground Surface ◽  
Nonlinear Least Squares ◽  
Geothermal Gradient ◽  
Geothermal Field ◽  
The Other ◽  
Temperature Measurements ◽  
Salton Sea ◽  
Depth Interval ◽  
Average Value

Shallow‐hole (<13 m) temperature measurements made at various depths and/or times may yield reliable values of geothermal gradient and thermal diffusivity if the groundwater table is shallow (a few meters) such that the effect of time‐dependent moisture content and physical properties is negligible. Two numerical methods based on nonlinear least‐squares curve fitting are derived to remove the effect of annual temperature wave at the ground surface. One method can provide information on the gradient and diffusivity as a function of depth while the other gives average value over the depth interval measured. Experiments were carried in six test holes cased with 2 cm OD PVC pipes in the Salton Sea geothermal field. A set of 5 to 7 thermistors was permanently buried inside the individual pipes with dry sand. Consistent gradient determinations have been obtained with both numerical methods from six monthly observations. By linearly extrapolating the depths to the 100°C and 200°C isotherms from the calculated gradients and mean ground temperatures, we have found good agreement with the nearby deep‐well data for four holes. Discrepancy is found for two holes, one of which is located near the field of [Formula: see text] mud volcanoes and the other near the volcanic Red Hill, reflecting complicated local hydrologic conditions.

scholarly journals DISTRIBUTION AND RACE COMPOSITION OF DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) IN BULGARIA / EXTENSION Y RAZAS DEL MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) EN BULGARIA / ÉTENDUE ET RACES DE LA ROUILLE (Plasmopara halstedii (Farl.) Berl. and de Toni) EN BULGARIE

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova
Keyword(s):  
Downy Mildew ◽  
Resistance Gene ◽  
The Other ◽  
Plasmopara Halstedii ◽  
North West ◽  
North East ◽  
Race 1 ◽  
Race 2 ◽  
Production Areas ◽  
Number Of Authors

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.

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