scholarly journals Integrated Remote Sensing and Geophysical Investigations of the Geodynamic Activities at Lake Magadi, Southern Kenyan Rift

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Akinola Adesuji Komolafe ◽  
Zacharia Njuguna Kuria ◽  
Tsehaie Woldai ◽  
Marleen Noomen ◽  
Adeleye Yekini Biodun Anifowose
Keyword(s):  
Heat Source ◽  
Hot Springs ◽  
Thermal Structure ◽  
Geophysical Methods ◽  
Geothermal Gradient ◽  
Rift System ◽  
Aeromagnetic Data ◽  
Lake Magadi ◽  
Ground Investigation ◽  
Geophysical Investigations

The tectonic lineaments and thermal structure of Lake Magadi, southern Kenyan rift system, were investigated using ASTER data and geophysical methods. Five N-S faults close to known hot springs were identified for geoelectric ground investigation. Aeromagnetic data were employed to further probe faults at greater depths and determine the Curie-point depth. Results indicate a funnel-shaped fluid-filled (mostly saline hydrothermal) zone with relatively low resistivity values of less than 1 Ω-m, separated by resistive structures to the west and east, to a depth of 75 m along the resistivity profiles. There was evidence of saline hydrothermal fluid flow toward the surface through the fault splays. The observed faults extend from the surface to a depth of 7.5 km and are probably the ones that bound the graben laterally. They serve as major conduits for the upward heat flux in the study area. The aeromagnetics spectral analysis also revealed heat source emplacement at a depth of about 12 km. The relative shallowness implies a high geothermal gradient evidenced in the surface manifestations of hot springs along the lake margins. Correlation of the heat source with the hypocenters showed that the seismogenetic zone exists directly above the magmatic intrusion, forming the commencement of geodynamic activities.

scholarly journals Geochemical Characterization of Nyamyumba Hot Spring, Northwest Rwanda

2021 ◽  
Author(s):  
Francois Hategekimana ◽  
Theophile Mugerwa ◽  
Cedrick Nsengiyumva ◽  
Digne Rwabuhungu ◽  
Juliet Confiance Kabatesi
Keyword(s):  
Hot Springs ◽  
Hot Spring ◽  
Geothermal Gradient ◽  
Hot Water ◽  
World Health ◽  
Rift System ◽  
Volcanic Complex ◽  
East African Rift System ◽  
Recreational Waters ◽  
Lake Kivu

Abstract Hot spring is a hot water that is naturally occurring on the surface from the underground and typically heated by subterranean volcanic activity and local underground geothermal gradient. There are four main hot springs in Rwanda such as: Kalisimbi, Bugarama, Kinigi and Nyamyumba former name Gisenyi hot springs. This research focused on the geochemical analysis of Nyamyumba hot springs located near the fresh water of Lake Kivu. Nyamyumba hot springs are located in the western branch of the East African Rift System and they are located near Virunga volcanic complex, explaining the rising and heating of water. The concentrations of Sulfate, Iron, Ammonia, Alkalinity, Silica, Phosphate, Salinity, Alkalinity, and Conductivity using standard procedures were measured. The results showed that hot spring water has higher concentrations of chemicals compared to Lake Kivu water and the geochemistry of these hot springs maybe associated with rock dissolution by hot water. The measured parameters were compared with World Health Organization (WHO) standards for recreational waters and it has been identified that Nyamyumba hot spring are safe to use in therapeutic activities (Swimming).

Three‐dimensional model of the Koyna area of Maharashtra State (India) based on the spectral analysis of aeromagnetic data

Geophysics ◽  
1983 ◽  
Vol 48 (7) ◽  
pp. 964-974 ◽  
Author(s):  
J. G. Negi ◽  
P. K. Agrawal ◽  
K. N. N. Rao
Keyword(s):  
Spectral Analysis ◽  
Case History ◽  
Three Dimensional ◽  
Aeromagnetic Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Block Model ◽  
Deccan Volcanism ◽  
Geophysical Investigations

The estimation of thickness of trap rocks in the earthquake‐affected Koyna area is an important parameter for revealing the topography that existed before the Deccan volcanism. In the present work, a case history is presented delineating a three‐dimensional block model for the Koyna area by the spectral analysis of aeromagnetic data. The thickness in the area was found to vary from 700 to 2200 m, which correlates well with the results of other geophysical investigations.

Chasing the Magma Chamber: MT meets Geodynamics and Seismology – A numerical case study of magmatic plumbing at Oldoinyo Lengai Volcano

2021 ◽  
Author(s):  
César Daniel Castro ◽  
Miriam Christina Reiss ◽  
Arne Spang ◽  
Philip Hering ◽  
Luca de Siena ◽  
...  
Keyword(s):  
Magma Chamber ◽  
Transfer Functions ◽  
Geophysical Methods ◽  
Gravity Anomalies ◽  
Active Volcano ◽  
Rift System ◽  
East African Rift System ◽  
Plumbing System ◽  
East African ◽  
Oldoinyo Lengai

<p>How well can geophysical methods image magmatic systems? Geophysical methods are commonly used to image magmatic systems; however, synthetic studies which give insights into the resolution of such methods and their interpretational scope are rare. Gravity anomalies, magnetotelluric, seismological and geodynamical modelling all have a different sensitivity to the rock parameters and are thus likely complementary methods. Our study aims to better understand their interplay by performing joint modelling of a synthetic magmatic system.  Our model setup of a magma chamber is inspired by seismological observations at the Natron plumbing system including active volcano Oldoinyo Lengai within the East African Rift system. The geodynamic modelling is guided by shear-wave velocity anomalies and it is constrained by a large Bouguer gravity anomaly which is modelled by a voxel-based gravity code. It yields the 3D distribution of several geological parameters (pressure, temperature, stress, density, rock type). The parameters are converted into a 3D resistivity distribution. By 3D forward modelling including the topography, synthetic MT transfer functions (phase tensor, induction vectors) are calculated for a rectangular grid of 441 sites covering the area. The variation of geodynamic parameters and/or petrological relations alters the related resistivity distribution and thus yields the sensitivity of MT responses to geodynamic parameters. In turn, MT observations may constrain geodynamic modelling by inverting MT transfer functions. The inversion is performed allowing for the recent seismicity distribution beneath the Natron plumbing system, assuming that active seismic areas are related to enhanced resistivity. The inversion is performed for a realistic distribution (in view of logistic accessibility) of about 40 MT sites.</p><p>By combining multiple forward models, this study yields insights into the sensitivity of different observables and thus provides a valuable base on how MT, gravity and seismological observations can help imaging a complex geological setting.</p>

Geology and petroleum prospectivity of the deepwater Otway and Sorell basins: new insights from an integrated regional study

2011 ◽  
Vol 51 (2) ◽  
pp. 692 ◽  
Author(s):  
Andrew Stacey ◽  
Cameron Mitchell ◽  
Goutam Nayak ◽  
Heike Struckmeyer ◽  
Michael Morse ◽  
...  
Keyword(s):  
Continental Margin ◽  
Regional Scale ◽  
Rift System ◽  
Aeromagnetic Data ◽  
Regional Study ◽  
Sequence Stratigraphic ◽  
Petroleum Systems ◽  
Tectonic History ◽  
Complex Structural ◽  
Potential Field Modelling

The frontier deepwater Otway and Sorell basins lie offshore of southwestern Victoria and western Tasmania at the eastern end of Australia’s Southern Rift System. The basins developed during rifting and continental separation between Australia and Antarctica from the Cretaceous to Cenozoic. The complex structural and depositional history of the basins reflects their location in the transition from an orthogonal–obliquely rifted continental margin (western–central Otway Basin) to a transform continental margin (southern Sorell Basin). Despite good 2D seismic data coverage, these basins remain relatively untested and their prospectivity poorly understood. The deepwater (> 500 m) section of the Otway Basin has been tested by two wells, of which Somerset–1 recorded minor gas shows. Three wells have been drilled in the Sorell Basin, where minor oil shows were recorded near the base of Cape Sorell–1. As part of the federal government-funded Offshore Energy Security Program, Geoscience Australia has acquired new aeromagnetic data and used open file seismic datasets to carry out an integrated regional study of the deepwater Otway and Sorell basins. Structural interpretation of the new aeromagnetic data and potential field modelling provide new insights into the basement architecture and tectonic history, and highlights the role of pre-existing structural fabric in controlling the evolution of the basins. Regional scale mapping of key sequence stratigraphic surfaces across the basins, integration of the regional structural analysis, and petroleum systems modelling have resulted in a clearer understanding of the tectonostratigraphic evolution and petroleum prospectivity of this complex basin system.

scholarly journals 3-D Geothermal Model of the Lurestan Sector of the Zagros Thrust Belt, Iran

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2140 ◽  
Author(s):  
Matteo Basilici ◽  
Stefano Mazzoli ◽  
Antonella Megna ◽  
Stefano Santini ◽  
Stefano Tavani
Keyword(s):  
Structural Model ◽  
Thermal Structure ◽  
Frictional Heating ◽  
Analytical Calculation ◽  
Geothermal Gradient ◽  
Hydrocarbon Exploration ◽  
Flow Density ◽  
Northwestern Part ◽  
Thrust Belt ◽  
Analytical Methodology

The Zagros thrust belt is a large orogenic zone located along the southwest region of Iran. To obtain a better knowledge of this important mountain chain, we elaborated the first 3-D model reproducing the thermal structure of its northwestern part, i.e., the Lurestan arc. This study is based on a 3-D structural model obtained using published geological sections and available information on the depth of the Moho discontinuity. The analytical calculation procedure took into account the temperature variation due to: (1) The re-equilibrated conductive state after thrusting, (2) frictional heating, (3) heat flow density data, and (4) a series of geologically derived constraints. Both geotherms and isotherms were obtained using this analytical methodology. The results pointed out the fundamental control exerted by the main basement fault of the region, i.e., the Main Frontal Thrust (MFT), in governing the thermal structure of the crust, the main parameter being represented by the amount of basement thickening produced by thrusting. This is manifested by more densely spaced isotherms moving from the southwestern foreland toward the inner parts of orogen, as well as in a lateral variation related with an along-strike change from a moderately dipping crustal ramp of the MFT to the NW to a gently dipping crustal ramp to the SE. The complex structural architecture, largely associated with late-stage (Pliocene) thick-skinned thrusting, results in a zone of relatively high geothermal gradient in the easternmost part of the study area. Our thermal model of a large crustal volume, besides providing new insights into the geodynamic processes affecting a major salient of the Zagros thrust belt, may have important implications for seismotectonic analysis in an area recently affected by a Mw = 7.3 earthquake, as well as for geothermal/hydrocarbon exploration in the highly perspective Lurestan region.

scholarly journals Convection in an internally heated stratified heterogeneous reservoir

2019 ◽  
Vol 870 ◽  
pp. 67-105 ◽  
Author(s):  
Angela Limare ◽  
Claude Jaupart ◽  
Edouard Kaminski ◽  
Loic Fourel ◽  
Cinzia G. Farnetani
Keyword(s):  
Heat Source ◽  
Scaling Laws ◽  
Lower Layer ◽  
Thermal Structure ◽  
Internal Heat ◽  
Source Distribution ◽  
Heat Sources ◽  
Homogeneous Fluid ◽  
Earth’S Mantle ◽  
Lower Fluid

The Earth’s mantle is chemically heterogeneous and probably includes primordial material that has not been affected by melting and attendant depletion of heat-producing radioactive elements. One consequence is that mantle internal heat sources are not distributed uniformly. Convection induces mixing, such that the flow pattern, the heat source distribution and the thermal structure are continuously evolving. These phenomena are studied in the laboratory using a novel microwave-based experimental set-up for convection in internally heated systems. We follow the development of convection and mixing in an initially stratified fluid made of two layers with different physical properties and heat source concentrations lying above an adiabatic base. For relevance to the Earth’s mantle, the upper layer is thicker and depleted in heat sources compared to the lower one. The thermal structure tends towards that of a homogeneous fluid with a well-defined time constant that scales with $Ra_{H}^{-1/4}$, where $Ra_{H}$ is the Rayleigh–Roberts number for the homogenized fluid. We identified two convection regimes. In the dome regime, large domes of lower fluid protrude into the upper layer and remain stable for long time intervals. In the stratified regime, cusp-like upwellings develop at the edges of large basins in the lower layer. Due to mixing, the volume of lower fluid decreases to zero over a finite time. Empirical scaling laws for the duration of mixing and for the peak temperature difference between the two fluids are derived and allow extrapolation to planetary mantles.

scholarly journals Bacteria and Archaea diversity within the hot springs of Lake Magadi and Little Magadi in Kenya

2016 ◽  
Vol 16 (1) ◽  
Author(s):  
Anne Kelly Kambura ◽  
Romano Kachiuru Mwirichia ◽  
Remmy Wekesa Kasili ◽  
Edward Nderitu Karanja ◽  
Huxley Mae Makonde ◽  
...  
Keyword(s):  
Hot Springs ◽  
Lake Magadi

Geothermal gradients in the Hinton area of west-central Alberta

1982 ◽  
Vol 19 (4) ◽  
pp. 755-766 ◽  
Author(s):  
H. L. Lam ◽  
F. W. Jones ◽  
C. Lambert
Keyword(s):  
Hot Springs ◽  
Rocky Mountain ◽  
Geothermal Gradient ◽  
Temperature Data ◽  
Petroleum Exploration ◽  
Well Logs ◽  
Thermal Gradients ◽  
Disturbed Region ◽  
West Central ◽  
Exploration Well

Temperature data from petroleum exploration well logs of 3360 wells in a region of west-central Alberta are used to estimate thermal gradients. A relatively high geothermal gradient (~36 °C/km) of oblong shape located near Hinton is observed. The axis of the anomaly strikes approximately southwest–northeast and passes through the Miette Hot Springs area. It appears that water is heated at depth in the Rocky Mountain disturbed region and travels eastward and toward the surface along fault planes.

Soil organic carbon along a geothermal gradient in North-West Canada

2020 ◽  
Author(s):  
Tino Peplau ◽  
Edward Gregorich ◽  
Christopher Poeplau
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Forest Ecosystem ◽  
Hot Springs ◽  
Negative Relationship ◽  
Geothermal Gradient ◽  
Soil Warming ◽  
North West ◽  
Discontinuous Permafrost

<p>Global warming will increase soil microbial activity and thus catalyse the mineralisation of soil organic carbon (SOC). Predicting the dynamics of soil organic carbon in response to warming is crucial but associated with large uncertainties, owing to experimental limitations. Most studies use in-vitro incubation experiments or relatively short-term in-situ soil warming experiments. Long-term observations on the consequences of soil warming on whole-profile SOC are still rare. Here, we used a long-term geothermal gradient in North-West Canada to study effects of warming on quantity and quality of SOC in an aspen forest ecosystem.</p><p>The Takhini hot springs are located within the region of discontinuous permafrost in the southern Yukon Territory, Canada. The springs warm the surrounding soil constantly and lead to a horizontal temperature gradient of approximately 10°C within a radius of 100 meters. As these natural springs heat the ground for centuries and the forest ecosystem surrounding the springs is relatively homogenous, the site provides ideal conditions for observing long-term effects of soil warming on ecosystem properties. Soils were sampled at four different warming intensities to a depth of 80 cm and analysed for their SOC content and further soil properties in different depths. </p><p>For the bulk soil, we found a significant negative relationship between soil temperature and SOC stocks. This confirms that climate change will most likely induce SOC loss and thus a positive climate- carbon cycle feedback loop. The response of five different SOC fractions to warming will also be presented.</p>

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