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1.
Through a systematic observation of water level and temperature, and a comprehensive analysis of the data on major/trace elements, nitrite, hydrogen-oxygen isotopes, the conclusion has been drawn that there are two relatively independent groundwater systems （cool water and hot water）, and the geochemical indicators of hot/cool waters are described. The cool water system is relatively enriched in Ca^2＋, Mg^2＋ and HCO3^-. Its TDS is relatively low, about 1400-1800 mg/L. The hot water system is relatively enriched in K^＋, Na^＋, Cl^- and SO4^2-. Its TDS is relatively high, about 2200-2300 mg/L. The cool water system is enriched in Ba, Ga, Cd, and the hot water system is enriched in B, Ti, Cr, Ni, Cu, Mo, Rb, and Cs, relatively. Especially, the contents of Rb and Cs in the hot water system are more than five times as high as those in the cool water system. The NO3^- contents of cool water discharged from the gold mine are relatively high, and those of hot water are extremely low. The 8D and 8-80 values follow an increasing order of surface water〉mine cool water〉mine hot water. The cool water comes mainly from the lateral supply of phreatic water, while the hot water comes mainly from the vertical supply of deeply circulating structure-fracture water. The ratio of cool water over hot water was estimated to be about 1：1 by a water quality model..  相似文献   

2.
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   

3.
On the Kuril Islands there are 85 volcanoes, 39 of which are active. Hot springs and mud pots are wide spread in this area and have significant inputs on the chemical composition of the surrounding surface waters and environment. We present results of trace elements as well as data on H, O, S, and He isotope ratios for hydrothermal systems of the Mendeleev Volcano （Kunashir Island） and surrounding surface waters. Water and gas samples were taken from springs and holes as well as creeks and the Lesnaya River. Among the thermal water types, three main groups can be distinguished. The first group includes the waters, in which SO4^- ion predominant. The water temperature on the surface reaches 97℃, and TDS varies from a few g/L to 7 g/L. These waters are acid to superacid with pH values ranging 0.6 to 2.3. The second group is sodium-chloride waters. A maximum TDS is 14.2 g/L. The waters are neutral or alkaline; pH varies from 6.9 to 8.2. The third group is the sodium-chloride-sulfate-bicarbonate water. The Stolbovskie springs, located in the periphery of the Mendeleev Volcano are representative of this type. The pH of these waters is close to neutral. TDS is 1.9 g/L. They are rather the derivatives of sodium-chloride waters arisen from dilution of them by subsurface waters. The Kuslyi Creek and Lesnaya River are located near the Mendeleev Volcano. The most acid springs discharge into the Kislyi Creek as a result pH of this creek being 2.5, and contents of most elements rather high. For example, the contents of dissolved solids of Si, Fe, Al, Mn, Zn, in waters of the Kislaya Creek are 22.1, 8.1, 6.2, 1.29, and 0.28 mg/L, and correspondently. The water of the Lesnaya River, （Before the Kislyi Creek, pH is about 8 with TDS 102 mg/L, but after the Kuslyi Creek, pH decreases and the concentrations of chemical elements increase. Debit of the Kislayi Creek in summer season is about 370 L/sec. It means that every day only this small creek inputs in the Lesnay River about 706 kg of Si;  相似文献   

4.
The chemical and isotopic characteristics of the water and suspended particulate materials（SPM） in the Yangtze River were investigated on the samples collected from 25 hydrological monitoring stations in the mainsteam and 13 hydrological monitoring stations in the major tributaries during 2003 to 2007. The water samples show a large variation in both δD（ 30‰ to 112‰） and δ18O（ 3.8‰ to 15.4‰） values. Both δD and δ18O values show a decrease from the river head to the Jinsha Jiang section and then increase downstream to the river mouth. It is found that the oxygen and hydrogen isotopic compositions of the Yangtze water are controlled by meteoric precipitation, evaporation, ice（and snow） melting and dam building. The Yangtze SPM concentrations show a large variation and are well corresponded to the spatial and temporal changes of flow speed, runoff and SPM supply, which are affected by the slope of the river bed, local precipitation rate, weathering intensity, erosion condition and anthropogenic activity. The Yangtze SPM consists of clay minerals, clastic silicate and carbonate minerals, heavy minerals, iron hydroxide and organic compounds. From the upper to lower reaches, the clay and clastic silicate components in SPM increase gradually, but the carbonate components decrease gradually, which may reflect changes of climate and weathering intensity in the drainage area. Compared to those of the upper crust rocks, the Yangtze SPM has lower contents of SiO2, CaO, K2 O and Na2 O and higher contents of TFe2 O3 and trace metals of Co, Ni, Cu, Zn, Pb and Cd. The ΣREE in the Yangtze SPM is also slightly higher than that of the upper crust. From the upper to lower reaches, the CaO and MgO contents in SPM decrease gradually, but the SiO2 content increases gradually, corresponding to the increase of clay minerals and decrease of the carbonates. The δ30SiSPM values（ 1.1‰ to 0.3‰） of the Yangtze SPM are similar to those of the average shale, but lower than those of the granite rocks（ 0.3‰ to 0.3‰）, reflecting the effect of silicon isotope fractionation in silicate weathering process. The δ30SiSPM values of the Yangtze SPM show a decreasing trend from the upper to the middle and lower reaches, responding to the variation of the clay content. The major anions of the river water are HCO 3, SO 4 2, Cl, NO 3, SiO 4 4 and F and the major cations include Ca2＋, Na＋, Mg2＋, K＋ and Sr2＋. The good correlation between HCO3-content and the content of Ca2＋may suggest that carbonate dissolution is the dominate contributor to the total dissolved solid（TDS） of the Yangtze River. Very good correlations are also found among contents of Cl, SO4 2, Na＋, Mg2＋, K＋and Sr2＋, indicating the important contribution of evaporite dissolution to the TDS of the Yangtze River. High TDS contents are generally found in the head water, reflecting a strong effect of evaporation in the Qinghai-Tibet Plateau. A small increase of the TDS is generally observed in the river mouth, indicating the influence of tidal intrusion. The F and NO3 contents show a clear increase trend from the upstream to downstream, reflecting the contribution of pesticides and fertilizers in the Chuan Jiang section and the middle and lower reaches. The DSi shows a decrease trend from the upstream to downstream, reflecting the effect of rice and grass growth along the Chuan Jiang section and the middle and lower reaches. The dissolved Cu, Zn and Cd in the Yangtze water are all higher than those in world large rivers, reflecting the effect of intensive mining activity along the Yangtze drainage area. The Yangtze water generally shows similar REE distribution pattern to the global shale. The δ30SiDiss values of the dissolved silicon vary from 0.5‰ to 3.7‰, which is the highest among those of the rivers studied. The δ30SiDiss values of the water in the Yangtze mainsteam show an increase trend from the upper stream to downstream. Its DSi and δ30SiDiss are influenced by multiple processes, such as weathering process, phytolith growth in plants, evaporation, phytolith dissolution, growth of fresh water diatom, adsorption and desorption of aqueous monosilicic acid on iron oxide, precipitation of silcretes and formation of clays coatings in aquifers, and human activity. The δ34SSO4 values of the Yangtze water range from 1.7‰ to 9.0‰. The SO4 in the Yangtze water are mainly from the SO4 in meteoric water, the dissolved sulfate from evaporite, and oxidation of sulfide in rocks, coal and ore deposits. The sulfate reduction and precipitation process can also affect the sulfur isotope composition of the Yangtze water. The87Sr/86Sr ratios of the Yangtze water range from 0.70823 to 0.71590, with an average value of 0.71084. The87Sr/86Sr ratio and Sr concentration are primary controlled by mixing of various sources with different87Sr/86Sr ratios and Sr contents, including the limestone, evaporite and the silicate rocks. The atmospheric precipitation and anthropogenic inputs can also contribute some Sr to the river. The δ11B values of the dissolved B in the Yangtze water range from 2.0‰ to 18.3‰, which is affected by multifactors, such as silicate weathering, carbonate weathering, evaporite dissolution, atmospheric deposition, and anthropogenic inputs.  相似文献   

5.
Obtained new data on major element contents, trace and REE concentrations of sedimentary bedrock and groundwaters in Lastochka spa, along with isotope data, allow solving the problem of origin and evolution of these groundwaters. In the Lastochka area, located in Primorye region （Far East of Russia）, two types of groundwater are found： groundwater （TDS 0.2-0.4 g/L, pH 7.3-7.5） with lower pCO2 levels and groundwater with higher dissolved mineral content （TDS 3.7-4.7 g/L, pH 5.8-6.4） and high pCO2 levels. Our studies proved that both types of groundwaters originated from meteoric water and water-sedimentary stratum interaction has played a main role in forming chemical composition of waters. The main gas composition in the high pCO2 groundwater is CO2, which may as high as 98% of the total amount of all gas. The pressure of CO2, calculated using the water analysis data is at about 0.6 bar, while one measured in the field could reach 2.6 bar. The pressure of CO2 in groundwater with low TDS is 10.2 bar. Our δ^13C data [δ^13C （gas）=-6.22 versus PDB] indicate that most of the ^13C in the free CO2 of Lastochka spa is of upper mantle origin. Sedimentary bedrock is mainly sandstone with a good permeability. Dominate minerals are K-feldspar, quartz and plagioclase and secondary minerals are calcite, limonite, cericite and kaolinite. Our results indicate that the role of mantle CO2 gas is crucial for highly mineralized groundwater. This type of groundwater evolved only during water-rock-gas interaction. Extreme dissolution of albite in the presence of CO2 gas leads to the formation of lower pH and drastic accretion TDS and Na content in high pCO2 water. The violent difference in the trace element concentration in waters is caused by more intensive weathering of primary minerals in the presence of CO2 gas.  相似文献   

6.
Auriferous cherts in the Middle Carboniferous Jinchang Formation are the dominant host rocks of auriferous quartz veins and mixed orebodies comprised of gold-bearing quartz veins and cherts in the Mojiang gold deposit.The rocks exhibit sedimentary texture and structure and are composed of hot-water deposited minerals.The FeO,Fe2O3,Au and Ag contents of the auriferous cherts are high;the Cr,Ni and Co contents are also high but significantly variable;MnO/TiO2 and TFe/TiO2 ratios are relatively higy.As viewed from a few diagrams that distinguish different chert formations,the auriferous cherts are in or near the range of hot-water deposited cherts.Because the correlation coefficients between Au contents and those of Cr, Ni of the rocks are negative,a great Au amount in the cherts might not be brought about by later hydrothermal alterations.The rare-earth elements,O and Si isotopic compositions of the auriferous cherts demonstrate that the cherts belong to hot-water deposited rocks.The later hydrothermal alterations made the petrochemical compositions of the cherts deviate from the characteristics of hot-water deposition.In general,the geological and geochemical features of the auriferous cherts demonstrate that the rocks were formed by hot water deposition.  相似文献   

7.
According to 73 snow samples collected in the southeast and southwest of Tibetan Plateau in January,2021,the characteristics of hydrogen and oxygen stable isotopes（δD and δ18O）fractionation in dry season and the influence of water vapor migration on the chemical composition change of snow profile were revealed by measuring the stable isotopes of hydrogen and oxygen and soluble inorganic ions in snow,and the relationship between stable isotopes of hydrogen and oxygen and climate and the composition and source of soluble inorganic ions were discussed. The results show that the local meteoric waterline of snowpack in the whole study area is δD=7. 86δ18O+11. 8（R2=0. 95）,which is close to the Lhasa winter meteoric waterline,and the slope and inter⁃ cept of the meteoric waterline in the southeast are slightly lower than those in the southwest. δD and δ18O fluctu⁃ ates from -178. 11% to -68. 07% and -23. 80% to -9. 61%,respectively,and the d-excess values fluctuate from 11. 03% to 23. 49%,showing low values of δD and δ18O in winter,and high d-excess values. The surface layer is relatively enriched in heavy isotopes,and the isotope values are higher than those of the lower snow sam⁃ ples,and the water vapor migration inside the snow makes the slope of the relationship between δD and δ18O dif⁃ ferent. The concentration sequence of the main soluble inorganic ions is Ca2+>SO42->Na+>NO3->Cl->K+>Mg2+> NH4+,of which Ca2+（42. 47%）,SO42-（23. 53%）accounted for the largest proportion of cation and anion,re⁃ spectively,and the average concentration of ions in the southeast was higher than that in the southwest. The re⁃ sults of principal component analysis show that terrigenous sources are the main source of ions in snow,and NH4+ and some NO3- are related to human activities. The backward air mass trajectory shows that the source of water vapor is related to the water vapor transport controlled by the upper-altitude westerly circulation,and most of the ions are terrestrial mineral dust carried by westerly winds in winter. © 2023 The Author(s).  相似文献   

8.
Fine disseminated gold deposits occurring along the southeastern margin of the Yangtze Plate belong to the epithermal type resulting from different systems of ore-forming fluids.According to their sources, the ore-forming fluids can be divided into four systems: a)meteoric water system; b)oil-brine system; c)basin-brine system;and d)magmatic-formation water system.The four hydrothermal systems are responsible for four types of gold deposits, respectively.The meteoric water system produces hot spring gold deposits. The basin-brines,which are derived from fissure water, structural water and absorbed water sealed up in strata, are responsible for the absin-brine-type deposits.The oil-brine system, having the same source as the bain-brines ,is characterized by the involvement of organic matter and is responsible for the oil-brine-type deposits. Inclusion fluid data show that there are obvious differences in chemical composition and carbon, oxygen,hydrogen and sulfur isotopes for these hydrothermal systems.Different metallogenic provinces, in which one of the four systems is dominant, can be recognized in the region.  相似文献   

9.
Hot springs are natural exposed points of the hydrothermal system. The hydrogeochemistry of hot springs can be used to interpret the formation of the hydrothermal system; and the ~(14)C dating can be used to evaluate the renewability of the hydrothermal system. The hot springs exposed from fault zones in western Guangdong are classified as granite fissure water and clastic rock fissure water, which are sampled and tested. The results of water chemistry analysis show that hot spring water is mainly HCO_3-Na type in the beginning, while the mixing of seawater leads to the increase of Cl~-. Hydrogen and oxygen isotopes indicate that these hot springs mainly come from atmospheric precipitation, and water-rock interactions produce oxygen isotope exchange reactions, where a significant "oxygen drift" phenomenon can be observed. The relationship between δ~(13)C and HCO_3~- indicates that there is a deep source of CO_2 "dead carbon" in hot spring water. This systematic error is not considered in the existing ~(14)C dating correction models. The ~(14)C age of the deep source "dead carbon" correction proposed in this paper is close to the ~(14)C age of the reverse chemical simulation correction, the Gonfiantinie model, and the Mook model. The deep source "dead carbon" correction method can improve the systematic error. Therefore, the ~(14)C age corrected by the deep source "dead carbon" may be more representative in terms of the actual age of geothermal water.  相似文献   

10.
In the Hunan-Guizhou-Guangxi area there have developed very thick bedded siliceous rocks of the late Sinian. The rocks have a fairly pure composition, with an average content of siliceous minerals exceeding 95%. They are relatively rich in Fe and Mn, and poor in Al, Ti and Mg. The Fe/Ti, (Fe+Mn)/Ti, Al/(Al+Fe+Mn) and U/Th ratios and the Al-Fe-Mn and Fe-Mn-(Ni+Co+Cu)×10 triangle diagrams all show that they are hydrothermal sedimentary siliceous rocks. In the rocks the total amount of REEs is low, the δCe shows an obvious negative anomaly and the 8Eu a weak anomaly, and LREE>HREE, all indicating that they are products of hydrothermal processes. The δ30Si and δ18O values, as well as the formation temperature of the rocks all clearly show that the silica forming the rocks comes from hot water. Besides, analyses of the depositional environment of the rocks using the MnO/TiO2 ratio and the δCe and δ30Si values yield the same conclusion that they are formed in environments from continental marginal slope  相似文献   

11.
Investigations on stratigraphy, geomorphology and neotectonic movement in the Eastern Kunlun Moun-tains show that there existed a series of ancient lakes, including some saline lakes. in the studied region about30,000 years ago, They were distributed south of the middle Kunlun fault. from the middle-upper reaches of thepresent Narin Gol River in the west to the Alag Lake-Tosou Lake in the east. Of these the ancient Narin GolLake and Kunlun Lake were mainly recharged by the hot water related to valcanos. so the B, Li and K con-tents are relatively high. The neotectonic movement that commenced at 30.000 a B.P. caused the river system in the EasternKunlun Mountains to invade southwards. as a result the ancient lake water was captured to recharge theQarhan area. Therefore, the hot springs related to recent volcanism and faulting on the southern bank of theupper reaches of the Narin Gol River became an important source of saline materials for the Qarhan Lake.  相似文献   

12.
In the coastal aquifers of Kaluvelly （Bengal coast, India）, the over exploitation of the main aquifer （the Vanur sandstone） has created a piezometric depression. Water flows from the sea towards inland. A salinization problem is questioned. The geochemical study was dedicated to major, minor and trace elements as well as isotope ratios （δ^18O, δD, δ^37Cl and ^87Sr/^86Sr）. The catchment comprises a crystalline bedrock hinterland （chamockites） overlaid by sediment. The Vanur and Cuddalore sandstones, the two main layers, are issued from the decay of chamockites upland. The geochemical feature of a water body is linked both to the composition of the hosted rock and the interaction time between water and rock. In the deeper parts of the Vanur aquifer, a mixture with long-residence time groundwaters has been evidenced. These waters can originate from a pocket of water entrapped in the Vanur or from the charnockites downward. No seawater intrusion could be assessed. Piezometric data suggest a possible hydraulic connection between the Cuddalore and the Vanur aquifers. Major, minor element data and isotope ratios do not allow to distinguish between old waters from the different aquifers. Data evidence the heterogeneity of the charnokite formation which is characterized by high Ba contents. On the whole, the two sandstones are depleted compared to charnockites in alkaline and earth-alkaline elements, and enriched in less soluble element such as Th or Zr. Trace elements in groundwaters waters from the chamockite aquifer exhibit a high concentration of Ba as compared to Vanur and Cuddalore waters. As Ba is a soluble element, the concentration of Ba in waters is related to the concentration in the hosted rocks. The Li concentration, slightly higher in Vanur rocks, allows to distinguish waters from the deeper parts of the Vanur aquifer. For insoluble elements such as Ti, the hosted rock signature cannot be seen. The Ti concentration in water samples seems to rely on the reaction progress rather than on the available amount. Trace element data show that waters recovered from chamockites and sandstone aquifers present different geochemical features. The host rock signature can be seen in the chamockite and Vanur aquifers for some alkaline and alkaline-earth elements （mainly Ba and Li）.  相似文献   

13.
The Sin Quyen-Lung Po district is an important Cu metallogenic province in Vietnam, but there are few temporal and genetic constraints on deposits from this belt. Suoi Thau is one of the representative Cu deposits associated with granitic intrusion. The deposit consists of ore bodies in altered granite or along the contact zone between granite and Proterozoic meta-sedimentary rocks. The Cu-bearing intrusion is sub-alkaline I-type granite. It has a zircon U-Pb age of ~776 Ma, and has subduction-related geochemical signatures. Geochemical analysis reveals that the intrusion may be formed by melting of mafic lower crust in a subduction regime. Three stages of alteration and mineralization are identified in the Suoi Thau deposit, i.e., potassic alteration; silicification and Cu mineralization; and phyllic alteration. Two-phase aqueous fluid inclusions in quartz from silicification stage show wide ranges of homogenization temperatures(140–383℃) and salinities(4.18wt%–19.13wt%). The high temperature and high salinity natures of some inclusions are consistent with a magmatic derivation of the fluids, which is also supported by the H-O-S isotopes. Fluids in quartz have δD values of –41.9‰ to –68.8‰. The fluids in isotopic equilibrium with quartz have δ~(18)O values ranging from 7.9‰ to 9.2‰. These values are just plotted in the compositional field of magmatichydrothermal fluids in the δD_(water) versus δ~(18)O_(water) diagram. Sulfide minerals have relatively uniform δ~(34)S values from 1.84‰ to 3.57‰, which is supportive of a magmatic derivation of sulfur. The fluid inclusions with relatively low temperatures and salinities most probably represent variably cooled magmatic-hydrothermal fluids. The magmatic derivation of fluids and the close spatial relationship between Cu ore bodies and intrusion suggest that the Cu mineralization most likely had a genetic association with granite. The Suoi Thau deposit, together with other deposits in the region, may define a Neoproterozoic subduction-related ore-forming belt.  相似文献   

14.
The isotopic composition of dissolved boron, in combination with the elemental concentrations of B, Cl and salinities in freshwater-seawater mixed samples taken from the estuary of the Changjiang River, the largest one in China, was investigated in detail in this study. Brackish water and seawater samples from the estuary of the Changjiang River were collected during low water season in November, 1998. Boron isotopic compositions were determined by the Cs2BO^＋2-graphite technique with a analytical uncertainty of 0.2‰ for NIST SRM 951 and an average analytical uncertainty of 0.8‰ for the samples. The isotopic compositions of boron, expressed in δ^11B, and boron concentrations in the Changjiang River at Nanjing and seawater from the open marine East Sea, China, are characterized by δ^11B values of -5.4‰ and 40.0‰, as well as 0.0272 and 4.43 mg B/L, respectively. Well-defined correlations between δ^11B values, B concentrations and Cl concentrations are interpreted in terms of binary mixing between fiver input water and East Sea seawater by a process of straightforward dilution. The offsets of δ^11B values are not related to the contents of clastic sediment and to the addition of boron. These relationships favor a conservative behavior of boron at the estuarine of the Changjiang River.  相似文献   

15.
Ground water from Mt. Fuji, located on the border of Yamanashi and Shizuoka prefectures, has relatively high concentrations of trace element vanadium. The concentration is about 50 μg/L around the mountain, and about 1 μg/L in other areas. The vanadium comes from the lava of the mountain. The water is utilized as a source of tap water around the mountain, and habitants are drinking and using the water for cooking. Recent reports by some researchers suggest health beneficial effects of drinking the water; drinking such water can lower blood glucose level in diabetic patients, and improve insulin-resistant status in healthy women. However, the concentration of vanadium in the ground water is too low as compared with the apparently effective concentration （100000 μg/L） in preceding reports. Furthermore, the effects of vanadium in the water on public health are not elucidated. In the present study the regional concentrations of vanadium in ground waters were investigated in Yamanashi prefecture, and standardized mortality rates （SMR） are compared preliminary with vanadium data in order to investigate the effect epidemiologically. SMR data were provided by Health, Labor and Welfare Ministry. We used the summarized SMR from 1998 to 2002. The data contain SMRs from total causes; total malignant neoplasm; stomach cancer; colorectal cancer; liver and intrahepatic bile duct cancer; trachea bronchus and lung cancer; all heart diseases; acute myocardial infarction; and cerebrovascular disease. There are eight secondary medical districts in Yamanashi prefecture, and one of them, Fuji-hokuroku （No.7）, corresponds to high-vanadium area. No SMIL except SMR from cerebrovascular disease in female, was lower in the district No.7 than other eight districts. On the other hand, SMRs from all heart diseases and from acute myocardial infarction of both male and female in the district No.7 were highest among the districts. SMR from all causes in male of No.7 was also highest among the districts.  相似文献   

16.
238 marine carbonate samples were collected from seven sedimentary sections ofthe entire late Palaeozoic (Permian, Carboniferous and Devonian) in the Upper Yangtze Plat-form, southwest China. Based on the absence of cathodoluminescence and very low Mn (gener-ally<50 ppm) contents of the samples, it is thought that they contain information on the orig-inal sea water geochemistry. The results of isotopic analyses of these samples are presented interms of δ~(13)C and ~(87)Sr/~(86)Sr ratios versus geological time. The strontium data, consistent withother similar data based on samples from North America, Europe, Africa and other areas inAsia, support the notion of a global consistency in strontium isotope composition of marinecarbonates. The strontium data exhibit three intervals of relatively low ~(87)Sr/~(86)Sr ratios in thelate Middle Devonian to early Late Devonian, Early Carboniferous and Early Permian, corre-sponding to global eustatic high sea level stands. The lowest ~(87)Sr/~(86)Sr ratio recorded in theLate Permian was probably caused by substantial basalt eruptions in the Upper Yangtze Plat-form at the time. Three corresponding periods of relatively high δ~(13)C values at roughly the samethe intervals were caused by a relatively high rate of accumulation of organic carbon duringsea level rises at these times. The deposition of coal was probably responsible for the increaseof sea water δ~(13)C at other times. The δ~(13)C values drop dramatically near theDevonian/Carboniferous, Carboniferous/Permian and Permian/Triassic boundaries, con-sistent with other similar data, which further support the notion that geological time boundariesare associated with mass extinction and subsequent rejuvenation.  相似文献   

17.
Olifeld waters from Cenoxoic and Mesozoic terrestrial and Paleozoic marine environments in the Tarim Basin show no obvious difference in water chemistry except Br and isotopic compositions.The Paleozoic marine strata have higher Br concentrations than the terrestrial sediments,and the lack of obvious relationship between Br and I suggests that Br is not,for the most part,derived from the degradation of organic matter.The oilfield waters are characterized by high TDS(total dissolved solids),ranging from 120000mg/L to 320000mg/L relatively low Mg,high Ca,Sr,and CF relative to Br of evaporating seawater,suggestive of enhanced water-rock interaction,OAA(organic acid anions)concentrations are generally lower than 1500mg/L with high values occurring over the temperature range from 95℃ to 140℃,in the Cambrian to Jurassic systems,and nearby unconformities.Organic acids are considered to be generated mainly from thermal maturation of kerogens during progressive burial of the Jurassic-Triassic and Cambrian-Ordovician systems,biodegradation of crude oils nearby unconformities,and thermochemical sulfate reduction in part of the Cambrian and Ordovician strata.High Al concentrations up to 3mg/L to 5.5mg/L tend to occur in the waters of high OAA or petroleum-bearing intervals,suggesting the presence of organic complexing agents.Calculation by SOLMINEQ.88 with updated database shows that AlAc^2 may account for more than 30% of the total Al.Isotopic measurements(δD,δ18O)provide evidence for the following types of waters:diagenetically-modified connate meteoric water from the Jurassic and Triassic strata;diagenetically-modified connate marine water from the Cambrian and Ordovician strata;subaerially-evaporated water from the Cenozoic and Cretaceous strata;and mixed meteoric-evaporated or/and diagenetically modified connate water from the Carboniferous strata and reservoirs adjacent to the J/C and T/C unconformities.Those waters with very negative δD values from -51.30‰to-53.80‰(SMOW) and positive δ18O values from 2.99‰to 4.99‰(SMOW)in the continuous burial of the Cambrian-Ordovician system are explained to have resulted from hydrocarbon-water and water-rock interactions.  相似文献   

18.
西藏羊八井地热水的氢、氧稳定同位素组成及氚含量   总被引：4，自引：0，他引：4  
Isotopic data on drill hole water and surface water samples from the Yengbajain geothermal area as well as an ice sample from the glacial amphitheater in the Mt. Nyainqintanglha to the northwest of the Yangbajain basin are presented in this paper. In consideration of isotopic fractionation during steam separation, the hydrogen and oxygen isotopic ratios for thermal waters collected at the mouths of drill holes have been calibrated. The D/H ratio of thermal waters is similar to that of local precipitation, indicating their meteoric origin. The δ D and δ^18O values of the thermal waters of --150--160 and -17-20‰, respectively are the lowest among those well-known geothermal fields in the world.The recharge area of the geothermal system is at elevation of about 4,800--5,000 m. Drill holes along the axis of a tongueshaped zone where loose Quaternary sediments have been cemented by siliceous material show greater δ D and δ^18O values and discharge tritiumfree thermal waters. It is suggested that the thermal waters may be derived from superhcated water and steam which find their way upwards along the tectonic fractures within the granitic base overlain by Quaternary sediments. The classification of drill hole geothermal waters have been made in accordance with their δ D and δ^18O values and chloride contents. The “oxygen shift” of the thermal waters seems to be 2‰, due to isotopic exchange reactions between geothermal waters and reservoir rocks  相似文献   

19.
The Rehai geothermal field in Tengchong County, Yunnan Province is a significant high-temperaturehydrothermal convective system. The geothermal reservoir is composed of granite. Various geothermometersare used to evaluate the reservoir temperature. The most likely temperature of the reservoir as representedby T_(Na-K-Ca) is about 230℃. The chemical and isotopic compositions of fluids before boiling within the reser-voir are estimated. The mixing and dilution of cold and warm waters are discussed. The Rehai geothermal fieldis a high-temperature (hot) water system with the subsurface boiling zone close to the surface. The reservoirpressure at different depths is calculated. And finally the water-rock equilibration is inferred.  相似文献   

20.
This paper presents the general situation and key techniques of the drilling well M-1 in Matouying dry hot rock exploration hole, Leting, Tangshan, Hebei Province. A series of problems have been studied on the sea water drilling fluid, high temperature resistant fresh water drilling fluid, screw composite drilling technique, screw hole coring technology, and high temperature, thus solving the difficulty of sea water drilling fluid well protection, poor stability of drilling fluid under high temperature, and low efficiency in hot dry rock drilling and coring drilling to ensure the safety of the borehole and improve drilling efficiency. The high temperature resistant double condensation and double density cement slurry system and relevant technical measures are adopted to ensure the quality of cementing in the high temperature environment. Through the understanding and analysis of the strata in this area, this work provides valuable experience for drilling in the same strata in the future. The final hole depth of the M-1 well in Matouying is 4502. 11m, and hot dry rock with a temperature of 150t is found at 3965 m, which is the first hot dry rock well with a temperature of more than 150°C in the Beijing-Tianjin-Hebei region so far. © 2022 Editorial Board of Geology and Exploration. All rights reserved.  相似文献   

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