X-Ray Diffraction and Petrographic Analysis of Magnet Cove Carbonatite Core, Arkansas

Geothermal activity and hydrothermal mineral deposits at southern Lake Bogoria, Kenya Rift Valley: Impact of lake level changes

Hot water springs are typical surface manifestations of a geothermal system, especially in low enthalpy, amagmatic systems. In many of these systems, numerous cold-water springs are often associated with hot water springs. The smaller number of hot water springs and the wider spatial distribution between them make it difficult to perform a comprehensive study of such a geothermal system. In this case, associated cold water springs can be of particular help in understanding the hydrogeological setting of the geothermal system which is vital information for any future geothermal exploration programs. There are 9 known hot springs in Sri Lanka, however they are spread over a larger area of the eastern lowlands of the country. On the other hand, there are over 225 known cold-water springs distributed among the hot water springs, making Sri Lanka a perfect location for a case study. Most hot water springs are located at a great distance from their recharge zone (~ 50-100 km). With the exception of very few springs, cold water springs have short recharge to discharge distances (< 25 km). Geochemical and isotopic studies of the hot springs and the nearby cold springs show that both kinds are of the same origin and recharge at similar altitudes (> 600m). The electrical resistivity of cold-water springs is comparatively higher than that of rain and fresh surface water, but lower than that of hot water springs. This suggests that these cold spring waters also travel longer through the fault/fracture network through which hot spring waters circulate from recharge zones to discharge zones. These observations of cold-water springs show that they are also part of the geothermal system in Sri Lanka and reveal important information about the fluid flow paths of the geothermal system. The results and observations of the present study highlight the importance of cold-water springs in understanding the hydrogeological setting of a geothermal system. In addition, the new knowledge will be of significant benefit to future geothermal exploration programs, particularly in systems with a smaller number of hot water springs spread over a larger area.

Chemical and isotopic characteristics and origin of spring waters in the Lanping–Simao Basin, Yunnan, Southwestern China

<p>In Geology, water plays a major role in the transformation of landscapes. Hot water springs can be exploited as geothermic resources. The first forms of life on Earth, cyanobacteria, lived in water. I studied these three examples with my students, implementing various educational strategies: field trips, academic conferences, and hands-on activities.</p><p>Example 1-Fields trips<br>In Marseille, I organised a geological outing in the Calanques, the protected rocky coves, which explains the geological history of the region as well and erosion and sedimentation phenomena. The Calanques are made of limestone rocks that were formed by the accumulation of marine organism skeletons at the bottom of a warm sea during the Secondary Era. During the Cretaceous period, the calcareous rocks were pushed to the surface through the tectonic trust and overlapping of the African and European plates. The topography formed (The Provencal and Pyrenean chain and its foothills) undergoes weathering, fractures and distorts under the action of water. The hot rainy periods allow chemical dissolution and facilitates the formation of karstic networks. The periods of glaciation during the quaternary provoke declining water levels and sculpted furthermore the ground thanks to glacial action. <br><br>In Eastern Africa, in Djibouti, exceptional field trips were possible with the students  to the sites of the Assal-Goubbhet lake. It is a place like no other, a large depression 150 meters under the sea level.We studied the specific hydrological exchanges which explain the water hypersalinization. We measured the elevated thermal flows of the hot-water springs and linked our findings to tectonic activity. <br><br>Example 2 - Lab activity with stromatolites.</p><p>Water and the first Life forms.The 3.5 billion year stromatolites are bio-constructed and sedimentary rocks. They bear witness to the presence of life forms in the oceans, cyanobacteria. An exploration of the terrain and a practical session enabled the students to discover the action of these living organisms on the primal atmosphere and grasp the concept of Actualism in Geology. <br><br>Example 3 - Conference, field trip, and practical activities on geothermal activity.</p><p>Djibouti aims to become self-sufficient in energy by 2035 thanks to the production of 100% renewable electricity. The country relies on geothermal energy to reach that goal. We therefore studied this theme with the students of the French Highschool. Outings permitted to photograph the hot springs. Rain water infiltrates the ground and heats when in contact with the magma chambers less than 4 km under our feet. Through rock crack cause by earthquakes, the water comes to the surface in the form of steam and concentrates in the hot springs.</p><p>These examples remind our students of the essential role of water on our planet and its unequal distribution as a source of life, as a factor in the transformation of the landscapes or as a vital energy source. <br><br></p>

Western and central Utah has 16 areas whose wells or springs yield hot water (35 C or higher), warm water (20-34.5 C), and slightly warm water (15.5-19.5 C). These areas and the highest recorded water temperature for each are: Lower Bear River Area, 105 C; Bonneville Salt Flats, 88 C; Cove Fort-Sulphurdale, 77 C; Curlew Valley, 43 C; East Shore Area, 60 C; Escalante Desert, 149 C; Escalante Valley (Roosevelt, 269 C, and Thermo, 85C); Fish Springs, 60.5 C; Grouse Creek Valley, 42 C; Heber Valley (Midway, 45 C); Jordan Valley, 58.5 C; Pavant Valley-Black Rock Desert, 67 C; Sevier Desert ( Abraham-Crater Hot Springs, 82 C); Sevier Valley (Monroe-Red Hill, 76.5 C, and Joseph Hot Spring, 64 C); Utah Valley, 46 C; and Central Virgin River Basin, 42 C. The only hot water in eastern Utah comes from the oil wells of the Ashley Valley Oil Field, which in 1977 yielded 4400 acre-feet of water at 43 C to 55 C. Many other areas yield warm water (20 to 34.5 C) and slightly warm water (15.5 to 19.5 C). With the possible exception of the Roosevelt KGRA, Crater Hot Springs in the Sevier Desert, Escalante Desert, Pavant-Black Rock, Cove Fort-Sulphurdale, and Coyote Spring in Curlew Valley, which may derive their heat from buried igneous bodies, the heat that warms the thermal water is derived from the geothermal gradient. Meteoric water circulates through fractures or permeable rocks deep within the earth, where it is warmed; it then rises by convection or artesian pressure and issues at the surface as springs or is tapped by wells. Most thermal springs thus rise along faults, but some thermal water is trapped in confined aquifers so that it spreads laterally as it mixes with and warms cooler near-surface water. This spreading of thermal waters is evident in Cache Valley, in Jordan Valley, and in southern Utah Valley; likely the spreading occurs in many other artesian basins where it has not yet been recognized. In the East Shore Area thermal water trapped in confined aquifers warms water in overlying aquifers. Some of the areas of hot water, such as Roosevelt, Pavant-Black Rock, and Cove Fort-Sulphurdale, probably have a potential to produce electricity; the estimated potential at Roosevelt is 300 megawatts. But the many areas of warm and hot water whose temperatures are too low to produce electricity may still have their waters utilized for space heating, as is planned for Monroe, for greenhouses, and for the processing of farm produce. In this report are tables that give records of about 1500 thermal springs and wells, 66 yield hot water, more than 400 yield warm water, and more than 1000 yield slightly warm water. The records include location, ownership, temperature, yield, depth (of wells), geologic unit, and some chemical analyses.

Two igneous suites containing layered ultramafic-mafic cumulates were investigated with the intent to characterize the parental magma and to identify processes significant to the petrogenesis of these rocks. In both study areas, the early Cretaceous Sierra Nevada batholith and the Ivrea Zone, isotopic systematics of the cumulates were found to preserve the characteristics of the mantle-derived parental magma and to record the effects of fractional crystallization and assimilation. Modeling the relative importance of these processes and characterization of the material derived from the mantle are necessary to understanding the growth of the continental crust. Geologic mapping of 110 mi2 of the 125 to 110 Ma Stokes Mountain region reveals the presence of layered cumulate megaxenoliths and two coeval ring dike complexes. Petrographic analysis and geochemical modeling of 125 dominantly mafic and intermediate samples demonstrate the comagmatic nature of this suite. Combined oxygen, strontium and neodymium analysis of 22 samples indicates, however, that each ring complex was fed by an isotopically distinct parental magma (eNd(115) = +6.1, Sri = 0.70338, δ18O = 6.6‰ ; (eNd(115) = +5.7, Sri = 0.70372, δ18O = 6.7‰) both of which were derived from a variably contaminated, depleted mantle source. Minor assimilation of continentally-derived metasediments and mafic-ultramafic material of the Kings-Kaweah ophiolite further affected the isotopic evolution of the two subsuites. Hydrothermal alteration in the subvolcanic environment is recorded only by rare stoped xenoliths of 120 Ma hypabyssal intrusives. Late Hercynian (≈300 - 270 Ma) magmatism produced the 10 km thick Mafic Complex lying at the base of the Ivrea-Strona-Ceneri crustal cross section. δ18O analysis of 237 whole rock samples and 26 mineral separates reveals that presumably early intrusions into the cool crust preserve the depleted mantle signature of the modeled parental magma (eNd(115) = +7, Sri = 0.703, δ18O = 6.5‰) while later intrusions assimilated significant amounts of the 10 - 12‰ metapelite. Subsequent intrusion of voluminous basaltic magma fonned a large, convecting magma chamber in which assimilation was concentrated within boundary layers. Such lower crustal production of high-18O (δ18O = 8 - 10‰) mafic magmas is suggested as contributing to the petrogenesis of upper crustal Permian granites.

Contributions of abiotic and biotic processes on travertine deposition are still not well‐understood due to technical difficulties, despite that the travertines draw attention as analogues for ancient microbial carbonates and oil reservoirs. To evaluate their contributions, this study examined eight hot springs in Japan. Water chemistry analyses showed common downstream trends: a decrease in CO2 concentration and increases in CO32− concentration and pH. Mineralogical analysis showed that the constituent minerals of travertines at six hot springs were both calcite and aragonite, while one was just calcite and another only aragonite. Microscopic observations of travertine surfaces indicated the dominance of cyanobacteria secreting extracellular polymeric substances without a detectable amount of carboxyl groups. Small particles were sometimes entangled/covered by these cyanobacteria. Microelectrode measurements showed the occurrence of abiotic CaCO3 precipitation and photosynthetic induction/inhibition of CaCO3 precipitation, the extent of which was different at each site. By integrating these results, the contributions of abiotic and biotic processes were evaluated. Cyanobacteria inhabiting travertine surfaces were generally not calcified regardless of an ambient high CaCO3 saturation state; instead, they contributed to creating pore spaces and trap/bind suspended particles. Downstream CO2 degassing increased the CaCO3 saturation state by shifting carbonate chemical equilibrium and caused abiotic CaCO3 precipitation. Suspended particles trapped by cyanobacteria increased the surface area for crystal growth to further accelerate precipitation. The contribution of photosynthesis‐induced CaCO3 precipitation was low because of several factors, including variable cyanobacteria populations and photosynthetic inhibition of CaCO3 precipitation. The average contributions of photosynthesis‐induced CaCO3 precipitation, Ca2+ adsorption and abiotic precipitation in the eight hot springs were 16%, 3% and 81%, respectively, indicating predominance of the abiotic process for travertine deposition. Mineralogical composition of travertines significantly correlated with concentrations of SO42− and Mg2+, much more than with Mg/Ca ratio and water temperature, suggesting their importance for controlling CaCO3 polymorphs in travertines.

This paper reports the results of our studies, the chemical analysis of thermal spring’s waters and their geological settings, the use of different statistical methods to evaluate the origin of the dissolved constituents of spring waters and the estimation of the reservoir temperature of the associated geothermal fields of the Guelma region, Algeria. A major component in 13 spring water samples was analyzed using various techniques. The waters of the thermal springs at Guelma basin vary in temperature between 20 and 94°C. Q-mode hierarchical cluster analysis suggests three groups. The water springs were classified as low, moderate and high salinity. Mineral saturation indices (SI) calculated from major ions indicate the spring waters are supersaturated with the most of the carbonate minerals, and all of the spring water samples are under-saturated with evaporite minerals. The thermal spring waters have a meteoric origin, and all samples are immature with strong mixing between warm and shallow waters, where the temperatures of reservoirs to which the thermal waters are related ranged between 64° and 124°C. The deep circulation of meteoric waters in the study area is supplied by the high geothermal gradient around 4.5°C per 100 m and reaches a high temperature before rising to the surface. The estimated circulation depths ranged from 1425 and 3542 m.

AltaRock demonstration project on hold

Ikogosi warm spring is a unique tourist centre where warm and cold spring waters flow together. Consequently, understanding the hydrochemical processes and recharge source are critical to the sustainability and management of the warm spring. Hence, stable isotopes (δ18O and δ2H) and hydrochemical study of Ikogosi spring waters was carried out to conceptualize the recharge source and the extent of water-rock interaction on the hydrochemical evolution of the waters. The study approach involved field sampling and in-situ measurements of physico-chemical parameters followed by laboratory hydrochemical and stable isotope analyses of the spring water samples. The hydrochemical analysis revealed that Ikogosi spring water is alkaline in nature with values ranging between 7.4 and 9.0. The TDS ranges from 14.3 to 66.8 mg/L with mean value of 49.2mg/L while the TH is from 6.3 to 39.0mg/L with mean value of 27.61mg/L. All EC values for the sampled spring waters were below 1000µS/cm indicating fresh water. Ca2+ was the dominant cation with value ranging from 2.2-9.6mg/L while Cl- was the dominant anion with value ranging from 88.6-144.0mg/L. The spring water is low mineralized and hydrochemically potable. Rock-water interactions were the dominant processes controlling the major ion composition of the spring while the dominant water was Ca (Mg)-Cl type. Stable isotopes analysis revealed recharge from recent precipitation. Conclusively, Ikogosi spring waters have low EC and TDS along with low total hardness (TH) values suggesting a low mineralized soft fresh water system recharged from recent precipitation with limited residence time.

Pegmatites

Exploring the hydrogeochemical evolution of cold and thermal waters in the Sarein-Nir area, Iran using stable isotopes (δ18O and δD), geothermometry and multivariate statistical approaches

Previous articleNext article FreeThe Collecting Area of the Waters of the Hot Springs, Hot Springs, ArkansasA. H. PurdueA. H. Purdue Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 18, Number 3Apr. - May, 1910 Article DOIhttps://doi.org/10.1086/621726 Views: 142Total views on this site PDF download Crossref reports no articles citing this article.

Hydrogeochemical evaluation of thermal, mineral and cold waters between Bursa city and Mount Uludağ in the South Marmara region of Turkey

Geothermal zones and hot mineral springs are primarily associated with magmatism along the Eurasian Continental Margin. In our study, we examine the correlation between geothermal anomalies observed in Bulgarian territory and the magnetic anomalies produced by magmatic and metamorphic bodies. Specifically, if these magnetic sources are of relatively recent origin, they could contribute to heating the surrounding geological environment, thereby influencing geothermal patterns. We use geological and hydrological information, along with temperature distribution at depth, to clarify the geological environment. Next, we apply geophysical data processing and direct inversion techniques to compute the total field modulus and Euler solutions, refining the interpretation of magnetic sources and enabling a more precise evaluation of subsurface magnetic structures and their potential impact on geothermal activity. A thorough analysis of the geomagnetic field, including over forty described anomalies, is presented for the examined territory. The correlation between geothermal and magnetic anomalies is confirmed using the Chi-square test. The null hypothesis is rejected, and the zones that significantly contributed to this result are outlined. Our study identifies seven regions with the strongest correlations in terms of temperature and magnetic anomalies: (1) A broad area in the western part of the Moesian platform near Kozloduy, characterized by increased temperatures and moderate magnetic anomalies; (2) A well-defined area east of Sofia, the capital city, which features high temperatures and intense magnetic anomalies, as well as numerous hot springs; (3) The region north of Blagoevgrad, located at the foothills of the Rila Mountains, where the hottest spring, Sapareva Banya, can be found; (4) The lower course of the Struma River, near the town of Petrich, where higher temperatures coincide with a distinct group of magnetic anomalies caused by granite bodies locally enriched in ferromagnetic iron minerals; (5) A local area near Velingrad exhibiting high temperatures alongside magmatic bodies, set in a complex tectonic environment; (6) A confined zone to the north of Dospat, where rhyolites are exposed along a significant fault line; (7) A broad zone with the highest temperatures (exceeding 100 °C at a depth of 1,000 m) that aligns with magnetic anomalies from extensive outcrops of Precambrian metamorphic rocks. We analyze these relationships in the context of identified hydrogeological zones, providing a detailed examination of the spatial distribution of geothermal and magnetic features. Furthermore, we explore the correlation between these anomalies and the depth to the Curie point, as inferred from magnetic data, to better understand the thermal and magnetic structure of the region. Graphical Abstract The present study aims to identify the spatial distribution of geothermal zones in Bulgaria that coincide with the appearance of magnetic anomalies. To delineate geothermal anomalies, we use temperatures at a depth of 1000 m below the surface, obtained from temperature logs of wells. Magnetic anomalies are calculated from the vertical component of the anomalous geomagnetic field across Bulgaria. Additionally, we support our interpretation with geological information and hydrogeological zoning of mineral waters, including the distribution of hot springs. Two types of analysis are performed: (1) geophysical data processing in terms of magnitude calculation and the direct inverse method of Euler deconvolution, which outlines the magnetic sources, and (2) statistical examination using a Chi-square test. A uniform grid with over 200,000 cells is generated, with each cell containing geothermal and magnetic data organized by classes (levels). A contingency table is compiled that records the frequency of each combination of geothermal and magnetic classes. The Chi-square test results indicate a highly significant statistical correlation between geothermal and magnetic anomalies. Consequently, we reject the null hypothesis and conclude that geothermal activity and magnetic variations are closely linked, possibly due to shared geological structures, heat-altered magnetism, or fault systems. The cells that contribute most to this correlation are identified and discussed.