共查询到20条相似文献，搜索用时 31 毫秒
1.
Water samples from natural springs and artesian wells in the Abano region of northern Italy are characterized by anomalous temperatures and compositions. Concentrations of major components and oxygen isotopes in samples of these fluids have been interpreted in the context of the regional geologic environment, circulation of groundwaters, and reactions between rocks and circulating groundwaters. These considerations define sourceregions and pathlines of the groundwaters.Circulation of fluids in the Abano region is interpreted to be the result of meteoric water infiltration into outcrops of Permian and Mesozoic aquifers in the pre-Alps, which lie north of the Abano region. These aquifers have southerly dips and, therefore, extend under the Abano region at depths between 0.5 and 2.5 km. This aquifer geometry is conducive to forced convection both of aqueous ions derived from the evaporate, limestone and dolomite bearing formations, and of thermal energy along flow paths which extend from the outcrops in the sourceregions to depths of 2 km below the Abano region and upward along high angle faults to thermal springs. Local variation in compositions of water samples is consistent with the mixing of local meteoric waters and formation fluids that were ultimately derived from Alpine sources. 相似文献
2.
The geochemical characteristics of hydrothermal waters from the Phlegraean Fields (P.F.) (Naples, Italy) were analysed for minor and trace elements, selectively mobilised in hydrothermal systems such as B, F, Hg, As, Pb and Tl.The water samples, collected from a shallow aquifer likely to be fed by deeper fluids, showed various geochemical features, resulting from the mixing of three components: (1) surface waters of meteoric origin; (2) hot deep waters deriving from water-rock interaction and including deep waters of marine origin; (3) magmatic fluids rising from the local magma chamber, lying a few kilometres below the town of Pozzuoli.This setting, although very complex, provides a reliable means of studying the distribution of the investigated trace elements. In particular, within the Phlegraean area, high contents of B (0.1-48 mg/l), F (0.5-8 mg/l), As (16-6050 μg/l) and Hg (0.7-232 μg/l) were observed. The levels of thallium in the springs close to Solfatara (about 7 μg/l) were in line with those normally recorded in hydrothermal areas, whereas high levels of this element (up to 23.3 μg/l) were identified in other wells of the study area. Lead (1.3 to 29.1 μg/l) appears to be anomalous with respect to its normal content in groundwater (about 1 μg/l), owing to the presence of high-density brines at depth, which enhance the solubility of Pb in volcanic rocks under hydrothermal conditions.The distribution of the investigated trace elements in the Phlegraean Fields thermal area is probably related to the different ascent pathways of the fluids. Clearly, apart from the influence exerted by anomalous thermal conditions, each element shows a different behaviour, depending on its geochemical affinity with mineral phases and as a consequence of the different enthalpy values, which determine ion partitioning in gaseous phases.Based on geochemical evidences and on the distribution of minor and trace elements, the source processes of the investigated hydrothermal waters were defined. Five main groups were identified: (1) acid sulphate waters, resulting from mixing of meteoric water with magmatic gases (mainly H2S); (2) high sulphate-chloride waters, from a deep reservoir located in the major upflow zone; (3) waters associated with significant degassing of magmatic CO2; (4) waters from a deep geothermal neutral chloride reservoir, resulting from heating of marine water modified by water-rock interaction processes; (5) cold waters from the inner area, influenced by low-temperature, water-rock interaction processes. 相似文献
3.
ZHU Xiaoqing 《中国地球化学学报》2005,24(4):306-315
Experimental studies were undertaken on leaching of sedimentary rocks （ dolomite and sandstone） and Hg, Sb ores by distilled water under the condition of a completely open system （room temperature and room pressure）. The aim is to find whether the halogen elements or metal elements first enter the solution at the early stage of meteoric waters converting to groundwaters and ore fluids, and, at the same time, to understand how and when they enter distilled water solutions from the rocks. The experimental resuhs have shown that F and Cl began to enter the fluids in the initial period of thirty days. With increasing leaching duration, the amounts of the elements that entered the fluids increased steadily. During the period from 120 days to 150 days the amounts increased more drastically, followed a slow increase. It is found that the capability of Cl entering the solutions is much greater than that of F. Hg and Sb were found not to have entered the solutions till 120 days later. During this period of time the pH value of the solutions began to drop. As for Hg and Sb ores, Hg and Sb began to enter the solutions on the 60th or 90th day, greatly ahead of schedule, but the two metallic elements in the rock samples began to enter the solutions 150 days later. Relatively speaking, Hg is more easily leached out than Sb from the rocks. In some rock samples, Sb could be detected in the solutions at the end of the experiment. However, Cu, Pb and Zn had not been detected in the leaching solutions from the beginning to the end of the experiment. In the whole leaching process the pH value of the solutions tend to decrease slowly from 7.1 at the beginning to 6.5 at the end. That is to say, in the interaction between pure water and rock the halogen elements in the rocks were preferentially leached out and then entered the fluids. With increasing water/rock reaction duration and amount of halogen-group elements in the solution and with decreasing pH value of the solution, some active metallic elements began to release in small amounts. This experimental result can explain the source and mechanism of volatile components and trace metals in underground waters. Meanwhile, as for those ore deposits produced by ore fluids derived from meteoric waters, the experimental result is also helpful to the understanding of the geochemical variation trend at the initial stage of conversion of meteoric waters to ore fluids. 相似文献
4.
论湖南石门砷—（金）矿床的古热泉成因 总被引：4，自引：0，他引：4
湖南石门砷－（金）矿床属古热泉成因,具有典型的三层结构模式,矿体呈筒状;矿床中硅质体属热泉沉积的硅华,矿石中微量元素间该区现代热泉体系沉积物的类似;成矿溶液富Ｎａ＾２＾＋,Ｃａ＾２＾＋,Ｃｌ＾－,ＨＣＯ３＾－和ＳＯ４＾２＾－,也与该区现代热泉水成分相似。泉水的氢,氧,氩,氦同位素研究表明,成矿溶液中水主要为大气降水。提出了热泉型砷－（金）矿床的成矿模式：下渗的大气降水被深部热流体加热,在地层中循环 相似文献
5.
Groundwater chemistry and isotope data from 44 public supply wells in the Napa and Sonoma Valleys, California were determined to investigate mixing of relatively shallow groundwater with deeper hydrothermal fluids. Multivariate analyses including Cluster Analyses, Multidimensional Scaling (MDS), Principal Components Analyses (PCA), Analysis of Similarities (ANOSIM), and Similarity Percentage Analyses (SIMPER) were used to elucidate constituent distribution patterns, determine which constituents are significantly associated with these hydrothermal systems, and investigate hydrothermal contamination of local groundwater used for drinking water. Multivariate statistical analyses were essential to this study because traditional methods, such as mixing tests involving single species (e.g. Cl or SiO2) were incapable of quantifying component proportions due to mixing of multiple water types. Based on these analyses, water samples collected from the wells were broadly classified as fresh groundwater, saline waters, hydrothermal fluids, or mixed hydrothermal fluids/meteoric water wells. The Multivariate Mixing and Mass-balance (M3) model was applied in order to determine the proportion of hydrothermal fluids, saline water, and fresh groundwater in each sample. Major ions, isotopes, and physical parameters of the waters were used to characterize the hydrothermal fluids as Na–Cl type, with significant enrichment in the trace elements As, B, F and Li. Five of the wells from this study were classified as hydrothermal, 28 as fresh groundwater, two as saline water, and nine as mixed hydrothermal fluids/meteoric water wells. The M3 mixing-model results indicated that the nine mixed wells contained between 14% and 30% hydrothermal fluids. Further, the chemical analyses show that several of these mixed-water wells have concentrations of As, F and B that exceed drinking-water standards or notification levels due to contamination by hydrothermal fluids. 相似文献
6.
This study describes the hydrogeochemistry and distributions of As in groundwater from a newly investigated area of Burkina Faso. Groundwaters have been sampled from hand-pumped boreholes and dug wells close to the town of Ouahigouya in northern Burkina Faso. Although most analysed groundwaters have As concentrations of less than 10 μg L−1, they have a large range from <0.5 to 1630 μg L−1. The highest concentrations are found in borehole waters; all dug wells analysed in this study have As concentrations of <10 μg L−1. Skin disorders (melanosis, keratosis and more rare skin tumour) have been identified among the populations in three villages in northern Burkina Faso, two within the study area. Although detailed epidemiological studies have not been carried out, similarities with documented symptoms in other parts of the world suggest that these are likely to be linked to high concentrations of As in drinking water. The high-As groundwaters observed derive from zones of Au mineralisation in Birimian (Lower Proterozoic) volcano-sedimentary rocks, the Au occurring in vein structures along with quartz and altered sulphide minerals (pyrite, chalcopyrite, arsenopyrite). However, the spatial variability in As concentrations in the mineralised zones is large and the degree of testing both laterally and with depth so far is limited. Hence, concentrations are difficult to predict on a local scale. From available data, the groundwater appears to be mainly oxic and the dissolved As occurs almost entirely as As(V) although concentrations are highest in groundwaters with dissolved-O2 concentrations <2 mg L−1. The source is likely to be the oxidised sulphide minerals and secondary Fe oxides in the mineralised zones. Positive correlations are observed between dissolved As and both Mo and W which are also believed to be derived from ore minerals and oxides in the mineralised zones. The discovery of high As concentrations in some groundwaters from the Birimian rocks of northern Burkina Faso reiterates the need for reconnaissance surveys in mineralised areas of crystalline basement. 相似文献
7.
成矿热液的氢、氧同位素组成与其水的类型、水/岩交换的岩石成分和同位素组成、水/岩交换时的温度及水/岩交换程度(W/R比值大小)等诸多因素有关,微生物和有机质也对其有一定的影响。因此,仅通过简单投影的方法将成矿热液的氢、氧同位素值与一些所谓的标准值进行类比,由此就推断出热液中水的来源,这种方法是不可取的;尤其当成矿热液的氢、氧同位素值介于大气降水和岩浆水的值之间时,切忌滥用两种水混合成矿模式,因为实际情况往往并不是这样。本文以胶东乳山金矿床为例,展开了这方面的讨论。 相似文献
8.
《Applied Geochemistry》2000,15(4):455-474
Between 1987 and 1995 more than 100 chemical and isotopic analyses were carried out on the thermal fluids discharged at surface from wells and springs of the Euganean and Berician thermal district. Results for δD and δ18O in waters, δ13C in CO2 and in C1–C4 n-alkanes, δD in CH4, 3He/4He and 40Ar/36Ar ratios in natural gases were coupled with chemical analyses in an attempt to determine the main characteristics and evolutionary trends of thermal fluids emerging in the region. The isotopic and chemical composition of thermal waters has led to the postulation of a meteoric origin of discharged thermal fluids and of a “maturation” trend as water moves from the peripheral manifestations of the Berici Hills towards those of the Battaglia, Montegrotto and Abano springs in the inner part of the geothermal field. Numerical simulation suggested that the observed evolutionary path is consistent with differentiation due to processes of water–rock interaction.The results of bulk analyses have shown that the gases are made up mainly of N2 (65–95 vol%), CO2 (0.5–20.5 vol%) and CH4 (up to 10 vol%), with relatively high Ar and He contents (up to 1.5 vol% and 0.16 vol%, respectively) and detectable amounts of C2–C6 saturated hydrocarbons. The chemical and isotopic composition of the gases suggests that both the meteoric and crustal contributions to the natural discharges are significant, while any significant magmatic contribution, possibly related to vestiges of the volcanic activity that occurred in the Abano area during the Tertiary age, can be ruled out. 相似文献
9.
A hydrochemical study of the Hammam Righa geothermal waters in north-central Algeria 总被引：1，自引：0，他引：1
Mohamed Belhai Yasuhiro Fujimitsu Fatima Zohra Bouchareb-Haouchine Abdelhamid Haouchine Jun Nishijima 《中国地球化学学报》2016,35(3):271-287
This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal field, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 °C and the hot waters from 32.1 to 68.2 °C. All waters exhibited a near-neutral pH of 6.0–7.6. The thermal waters had a high total dissolved solids (TDS) content of up to 2527 mg/l, while the TDS for cold waters was 659.0–852.0 mg/l. Chemical analyses suggest that two main types of water exist: hot waters in the upflow area of the Ca–Na–SO4 type (Hammam Righa) and cold waters in the recharge zone of the Ca–Na–HCO3 type (Zaccar Mount). Reservoir temperatures were estimated using silica geothermometers and fluid/mineral equilibria at 78, 92, and 95 °C for HR4, HR2, and HR1, respectively. Stable isotopic analyses of the δ18O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge infiltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1–2.2 km. The hot waters then interact at depth with Triassic evaporites located in the hydrothermal conduit (fault), giving rise to the Ca–Na–SO4 water type. As they ascend to the surface, the thermal waters mix with shallower Mg-rich groundwater, resulting in waters that plot in the immature water field in the Na–K–Mg diagram. The mixing trend between cold groundwaters from the recharge zone area (Zaccar Mount) and hot waters in the upflow area (Hammam Righa) is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 < R < 29.2 %. We summarize these results with a geothermal conceptual model of the Hammam Righa geothermal field. 相似文献
10.
Numerous present-day hot springs and associated ancient Lianghe gold deposit occur in the central Tengchong block, SW China, associated with oceanic crust subduction. From the center outwards, the alteration zones in the hot spring of the Rehai consist of alunite and silica in a breccia zone, a kaolinite and illite zone, and a chlorite, illite, kaolinite zone. The gas phase in the hot spring is dominated by CO2 with δ13C ranging from −4.5‰ to −7.2‰. These features indicate a major magmatic origin of the hot spring gas. The 3He/4He ratios in the gas from central Tengchong vary from 1.56 to 5.88, approaching to those of the MORB. This is probably related to the ongoing subduction of the Indian plate beneath the Tengchong block. The hot spring waters in the central Tengchong block have much higher content of Au and other elements, e.g., Ag, As, Sb, and Tl, than other typical hot springs, such as Hasbrouck, Sulfer, etc. in the world. The hot springs with more mantle gas contribution and higher water temperature show more elevated Au contents, which implies that the metal in the hot spring was most likely contributed from the magmatic gas. The compiled D-O isotopes of the hot spring waters from previous studies suggest that they are primarily derived from meteoric water. A genetic model for the hot spring system in the central of Tengchong has been tentatively established. The gold-charged hot spring is genetically connected to an active magma chamber, which was produced by subduction of oceanic crust. The chamber is driving long-term surface meteoric circulation and constantly releasing magmatic volatiles enriched with metals. As hot spring water mixed with magmatic volatiles, causing decompression-boiling and forming hydraulic fractures to penetrate the roof of siliceous sinter, which induced the continuing metal deposition and formed the Lianghe hot spring. 相似文献
11.
ＧｅｏｃｈｅｍｉｓｔｒｙｏｆＴｈｅｒｍａｌ－ＭｉｎｅｒａｌＷａｔｅｒｓｉｎＳｉｐｉｎｇ＇ａｎＤｉｓｔｒｉｃｔ，ＳｈａｎｘｉＰｒｏｖｉｎｃｅ，Ｃｈｉｎａ￥ＷａｎＹａｎｘｉｎ；ＳｕｎＬｉａｎｆａ（ＤｅｐａｒｔｍｅｎｔｏｆＨｙｄｒｏｇｅｏｌｏｇｙａｎｄＥｎ... 相似文献
12.
The deposition of metal-rich black or reddish muds by many thermal springs in the Cordilleras and the Altiplano of Bolivia suggest that these geothermal waters may be related to those that once formed the world-class Bolivian tin, silver and gold mineralisation. The discharge temperatures of these springs are as high as 70 °C. According to δ18O, δD, tritium data and Ar/N2 ratios these waters are predominantly of meteoric origin. Less than 10% of the discharging thermal water represents deep-seated metal-rich thermal brines of at least 530 °C according to carbon exchange between CO2 and CH4. These brines ascend along tectonic faults and mix with low-temperature meteoric water in surface-near aquifers. The meteoric component of the thermal water is recharged in the high Cordilleras with residence times exceeding 50 years. The chemical composition of the thermal water is dominated by the rather inefficient low-temperature leaching of the surface-near aquifer rocks by meteoric water. The small fraction of metal-rich hot deep-seated water is not able to increase the metal content of the water mix to a level sufficient to classify these thermal waters as ore-bearing. Surface-near leaching is supported, e.g., by the B/Li ratios of the spring water of the Western Cordillera and Caleras/Pulacayo in the Eastern Cordillera that correspond very closely to that of the easily leachable glassy inclusions of the outcropping andesitic lavas. The often remarkable metal content of the muds deposited by the springs originate from efficient scavenging of heavy metals by ferric oxyhydroxides. Under the given arid to semi-arid climate the muds are additionally enriched in metals by wind-transported dust. The present study does support a relation of the actual thermal waters with neither the classical subduction-related Upper Tertiary tin, silver and gold mineralisation nor the supposed younger Sb mineralisation of Bolivia. 相似文献
13.
The dissolved ionic constitutents of groundwaters are,in part,a recored of the minerals and rocks in aquifers through which the water has flowed.The chemical composition and association of these major ions in groundwaters have been used to trace groundwater flow paths and sources,In general,the chemical compostion of water in carbonate-rock aquifers in dominated by calcium,magnesium,and bicarbonate,whereas sodium,chloride,and sulfate can be dominant ions in the water that comes from volcanic aquifers or clay minerals.Since the 1990‘s,we have dealt with the geochemistry of groundwaters from more than 100 springs and wells in southern Nevada and eastrn california ,USA for major solutes and trace elements.This paper compiles the hydrochemical data of major ions of these groundwaters.Based on major ion geochemistry,groundwaters from southern Nevada and eastern California can be classified as carbonate aquifer water,volcanic aquifer water,and mixing water (either mixing of cabonate and volcanic aquifer waters or mixing with local recharges),Piper and stiff diagrams of major ions have graphically shown the general chemical characteristics,classification,and mixing relationships of groundwaters from southern Nevada and eastern California. 相似文献
14.
The Gulf of Suez region is one of the most interesting geothermal areas in Egypt because of the high temperatures of its springs.The eastern and western shores of the Gulf of Suez are characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures.Variations of deuterium and oxygen-18 concentrations in thermal waters have been used to aid in describing the source of recharge in the Gulf of Suez hot springs.Isotope and geochemical data for the Gulf of Suez thermal waters suggest that recharge to the hot springs may not be entirely from the Gulf of Suez water,but possibly from the meteoric water that comes from areas of higher altitude surrounding the hot springs. 相似文献
15.
Massimo Angelone Carlo Cremisini Vincenzo Piscopo Marco Proposito Fabio Spaziani 《Hydrogeology Journal》2009,17(4):901-914
Arsenic occurrence in groundwater near the Cimino-Vico volcanoes (central Italy) was analysed considering the hydrostratigraphy and structural setting and the shallow and deep flows interacting within the Quaternary volcanics. Groundwater is the local source of drinking water. As documented in the past, arsenic in the groundwater has become a problem, and the European maximum allowable contaminant level was recently lowered to 10 μg/L. Chemical analyses of groundwater were conducted, sampled over an area of about 900 km2, from 65 wells and springs representative of the volcanic aquifer and thermal waters. Considering the type of aquifer, the nature of the aquifer formation and its substratum, the hydrochemical data highlight that the arsenic content of the groundwater is mainly connected with the hydrothermal processes in the volcanic area. Thermal waters (54–60°C) fed from deep-rising fluids show higher arsenic concentrations (176–371 μg/L). Cold waters sampled from the volcanic aquifer are characterized by a wide variability in their arsenic concentration (1.6–195 μg/L), and about 62% exceed the limit of 10 μg/L. Where the shallow volcanic aquifer is open to deep-rising thermal fluids, relatively high arsenic concentrations (20–100 μg/L) are found. This occurs close to areas of the more recent volcano-tectonic structures. 相似文献
16.
Chemical and water isotope ratios data for groundwaters from the Pozzo del Sale area in the Irpinia sector of the Southern Apennines are presented. The water chemistry of the aquifer system may initially be regarded as the result of easy and common, low temperature interaction between meteoric water and Late Messinian evaporites, which produce Ca-bicarbonate and Na-chloride passing through Ca-sulfate waters. However, a closer inspection reveals a more complicated geochemical setting consisting of: (1) two further Na-sulfate and Ca(Mg)-sulfate waters; (2) the existence of different meteoric recharge areas; (3) the mixing between the different groundwaters and allochthonous fluids from terrestrial mud volcanoes. The salinization mechanism and the local mineralogy were inferred by classical and novel ternary and binary diagrams. The presence of MgSO4- and Na2SO4-bearing minerals of non-marine or mixed origin other than gypsum and halite within the local evaporites suggests a mineralogical heterogeneity within the local Messinian evaporites. The paleoenvironment of this sector of the Gessoso–Solfifera Formation might have been composed of relatively small playa-lakes fed by seawater but also large amounts of continental waters of meteoric origin. 相似文献
17.
《Chemie der Erde / Geochemistry》2021,81(3):125797
Geothermal fields distributed in the southern Tibet Plateau rifts such as Yangbajing - Dangxiong basin, and the Yaluzangbu suture are characterized by intensive hydrothermal activity and high enrichment of trace elements (e.g., Li, Rb, Cs, B and Br) in geothermal springs. However, the origin of these elements and their enrichment mechanisms in those geothermal waters remain unclear. This study presents data for the enriched elements, incompatible elements, and B and Sr isotopes, in the geothermal water in the Tibetan Plateau and compares them with some typical geothermal fields worldwide, in an attempt to provide new insights into the origin and mechanism of the enrichment of these trace elements. The results indicate that all geothermal water samples from the Tibetan Plateau show more negative δ11B values than those from local precipitation and rivers. Considering the wide existence of a high-conductivity zone in the middle or even upper-crust interpreted to correspond to re-melt magmatic fluids in the Tibet, the main sources of the typical chemical composition of geothermal waters in the Tibetan Plateau can be classified into two main types: residual magmatic fluids derived from crustal partial remelting and deep circulated groundwater modified by water–rock interactions. In particular, the possible source of magmatic fluids may play a more significant role for special geochemical compositions of geothermal water in the Tibet. Such resources are beneficial for the development and utilization of the geothermal water itself and also serve as a stable source for feeding the salt lake resources. 相似文献
18.
The hydrogeological conditions in Uludag (Nilufer River catchment, Bursa, Turkey) were assessed, using time-domain electromagnetic soundings, electrical resistivity and induced polarisation tomography, to detect the most promising zones for new water-well siting, in order to increase the quantity of water for bottling. The hydrogeological model is quite complex: deep mineral and thermal water rises from a main vertical fault which separates two lithological complexes. The highly mineralised (deep) water is naturally mixed with low mineralised water at a shallow depth, 30–40 m; the mixed mineral water is found in some surface springs and shallow wells, while the highly mineralised water is found at depth in some unused deep wells located close to the main fault. All the water points (springs and wells) are located inside a “mineral water belt” on the north side of the Nilufer River. The geophysical survey confirmed the hydrogeological model and highlighted four promising zones for well siting (zones with very low electrical resistivity and high induced polarisation anomalies, corresponding to the main water-bearing faults). One of the geophysical anomalies, the furthest from the exploited sources, was verified by means of a test well; the drilling results have confirmed the water mixing model. 相似文献
19.
J. N. Andrews M. J. Youngman J. E. Goldbrunner W. G. Darling 《Environmental Geology》1987,10(1):43-57
The geochemistry of formation waters in the Molasse basin of Upper Austria has been investigated to ascertain the extent of
meteoric water replacement of the connate interstitial fluids in these sediments. The chemistry, isotopic composition, and
dissolved gas contents of the groundwaters and of oil and gas associated brines have been determined. The most superficial
sediments of the basin, the Innviertel (Miocene), have been completely flushed by meteoric waters within the last 200 ka.
The underlying Hall and Puchkirchen formations (Miocene/Oligocene) form gas reservoirs for biogenic methane, and the associated
formation waters are chemically and isotopically modified connate brines of the original marine deposition. In the northeastern
part of the basin, the connate brines of the deeper sediments (Cretaceous/Jurassic) have been partially or completely replaced
by meteoric waters, whereas in the south of the basin these sediments contain high salinity fluids which are substantially
of connate origin. These conclusions are supported by the stable isotope composition of the various brines. Oil-associated
brines from the Eocene sediments contain large amounts of dissolved radiogenic40Ar, which suggests that the oils have migrated from high-temperature environments. This is in contrast with the Puchkirchen,
for which the observed absence of radiogenic40Ar suggests that the biogenic methane has been formed in situ. The4He contents of these brines and of the Cretaceous/Jurassic groundwaters are, however, less than those in the overlying Puchkirchen
formation and suggest that He has been removed from the deeper sediments as a result of flushing by meteoric water. The ratios
of dissolved methane and nitrogen to argon increase with increasing ammonium content of the formation waters. All of these
parameters may be used as indices for the maturation of the system. The heavy noble gases, Kr and Xe, are abnormally abundant
in the dissolved gases, and this is attributed to geochemical concentration of these gases by adsorption onto shales in the
sediment sequence. The overall geochemical situation confirms the existence of separate hydraulic systems with little interconnection
in the several overlying geological horizons. 相似文献
20.
Jowshan geothermal system comprises 6 thermal springs with outlet temperatures ranging from 39.3 to 46.6°C. The thermal water of these springs is presently used for swimming and as a treatment for rheumatism, sinusitis and skin diseases. The pH value of these springs is slightly acidic to neutral and the electrical conductivities about 1500 μS/Cm. The presence of many faults in the area, the alignment of all springs along the Sirch Fault and the similar chemical and isotopic composition of all springs in combination with the hydrogeological setting and geochemistry of water samples indicate that these springs are associated with deep circulation of meteoric water. According to this heating mechanism, meteoric waters infiltrate through fault openings to depth and after heating by geothermal gradient rise to the ground surface due to the hydraulic and buoyancy forces, a mechanism which is common in the southern parts of Iran. The use of various chemical geothermometers and mineral equilibrium states suggests a range of temperature about 50–90°C for the reservoir of Jowshan geothermal system. 相似文献