Pub Date : 2024-02-11DOI: 10.1134/s0016702923700180
Sun Yuhang, Zhang Jinchuan, Xu Longfei, Li Jie, Li Qianchao, Chen Lei, Zhao Xingxu, Li Wei
Abstract
The Shangyun area is classified as a medium-high temperature geothermal region situated in western Yunnan, inside the tropical zone of Yunnan and Tibet. Granites exhibit a wide distribution, while active faults demonstrate a rather advanced state of development. Consequently, the geological conditions are favourable for the creation of geothermal resources. Drawing upon previous research findings and geothermal drilling data, this study undertakes an analysis of the principal geological factors contributing to the development of the Shangyun geothermal system in Yunnan. The investigation reveals several noteworthy characteristics of geothermal activity within the granite region, including proximity to heat sources, substantial thermal gradients, water accumulation within fractures, the coexistence of deep and shallow geothermal phenomena, and the occurrence of hot springs along extensive and profound fault lines. The determined ground heat flow value in the Shangyun area is 142.74 mW/m2, with its primary heat source being predominantly influenced by high mantle heat flow and the radioactive heat generation of the Lincang granite located in the eastern region with the mean rate of radioactive heat generation of 7.6 μW/m3. The reservoir space mostly consists of weathered crust and fracture type heat storage. Additionally, the upper Jurassic mudstone, which has a thickness ranging from 500 to 1000 m and a thermal conductivity of 2.39 W/(m K), serves as an effective regional cap layer. The dissolution of silicate has a significant impact on the composition of geothermal water, with the primary type being HCO3–Na. The process of atmospheric precipitation infiltration and recharge contributes significantly to the availability of ample water resources for geothermal systems. Based on an analysis of the electrical data pertaining to the region, it can be inferred that the primary source of the water supply originates from the eastern mountain. Furthermore, it is seen that the active fault serves as the conduit for the deep circulation of geothermal water. This study presents a comprehensive examination of several geothermal geological features, including heat source, heat storage, hot channel, and geothermal water, in order to build a geothermal model specific to the Shangyun region.
{"title":"Geothermal Development Model in Granite Area: a Case Study of Shangyun Area, Yunnan Province, China","authors":"Sun Yuhang, Zhang Jinchuan, Xu Longfei, Li Jie, Li Qianchao, Chen Lei, Zhao Xingxu, Li Wei","doi":"10.1134/s0016702923700180","DOIUrl":"https://doi.org/10.1134/s0016702923700180","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Shangyun area is classified as a medium-high temperature geothermal region situated in western Yunnan, inside the tropical zone of Yunnan and Tibet. Granites exhibit a wide distribution, while active faults demonstrate a rather advanced state of development. Consequently, the geological conditions are favourable for the creation of geothermal resources. Drawing upon previous research findings and geothermal drilling data, this study undertakes an analysis of the principal geological factors contributing to the development of the Shangyun geothermal system in Yunnan. The investigation reveals several noteworthy characteristics of geothermal activity within the granite region, including proximity to heat sources, substantial thermal gradients, water accumulation within fractures, the coexistence of deep and shallow geothermal phenomena, and the occurrence of hot springs along extensive and profound fault lines. The determined ground heat flow value in the Shangyun area is 142.74 mW/m<sup>2</sup>, with its primary heat source being predominantly influenced by high mantle heat flow and the radioactive heat generation of the Lincang granite located in the eastern region with the mean rate of radioactive heat generation of 7.6 μW/m<sup>3</sup>. The reservoir space mostly consists of weathered crust and fracture type heat storage. Additionally, the upper Jurassic mudstone, which has a thickness ranging from 500 to 1000 m and a thermal conductivity of 2.39 W/(m K), serves as an effective regional cap layer. The dissolution of silicate has a significant impact on the composition of geothermal water, with the primary type being HCO<sub>3</sub>–Na. The process of atmospheric precipitation infiltration and recharge contributes significantly to the availability of ample water resources for geothermal systems. Based on an analysis of the electrical data pertaining to the region, it can be inferred that the primary source of the water supply originates from the eastern mountain. Furthermore, it is seen that the active fault serves as the conduit for the deep circulation of geothermal water. This study presents a comprehensive examination of several geothermal geological features, including heat source, heat storage, hot channel, and geothermal water, in order to build a geothermal model specific to the Shangyun region.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-11DOI: 10.1134/s0016702923700192
Abstract
The Hetao Plain, located in western Inner Mongolia, China, has been used for irrigation since the second century BC. Sixty-five samples were collected, including fifty-nine groundwater and six surface water samples, for hydrochemical and oxygen and hydrogen stable isotope analysis to assess the impact of irrigation on arsenic mobilization in groundwater in the study area. The total dissolved arsenic concentration in groundwater and surface water ranged from 3.2 to 764.8 μg/L and from 6.2 to 11.2 μg/L, respectively, generally exceeding 50 μg/L in groundwater, where the reducing environment prevails. The primary groundwater recharge source was a shallow aquifer that receives a considerable amount of irrigation water. The high arsenic content in groundwater was attributed to hydrochemical processes caused by vertical leaching of dissolved halite from the unsaturated zone, which was determined based on the molar Cl/Br ratios analysis. The oxygen and hydrogen stable isotope analysis of groundwater demonstrated the mixing between the groundwater and Yellow River water. An association between lateral recharge and mixing, evaporation, leaching, vertical mixing, and arsenic enrichment in groundwater was established based on the correlation between Cl– concentration and δ18O values. In an anaerobic groundwater environment, nitrate from nitrogen fertilizers indirectly oxidized As(III) to As(V).
{"title":"Impact of Irrigation on Arsenic Mobilization in Groundwater from the Hetao Plain, Northern China: Evidence from Cl/Br Ratios and Stable Isotopes","authors":"","doi":"10.1134/s0016702923700192","DOIUrl":"https://doi.org/10.1134/s0016702923700192","url":null,"abstract":"<span> <h3>Abstract</h3> <p>The Hetao Plain, located in western Inner Mongolia, China, has been used for irrigation since the second century BC. Sixty-five samples were collected, including fifty-nine groundwater and six surface water samples, for hydrochemical and oxygen and hydrogen stable isotope analysis to assess the impact of irrigation on arsenic mobilization in groundwater in the study area. The total dissolved arsenic concentration in groundwater and surface water ranged from 3.2 to 764.8 μg/L and from 6.2 to 11.2 μg/L, respectively, generally exceeding 50 μg/L in groundwater, where the reducing environment prevails. The primary groundwater recharge source was a shallow aquifer that receives a considerable amount of irrigation water. The high arsenic content in groundwater was attributed to hydrochemical processes caused by vertical leaching of dissolved halite from the unsaturated zone, which was determined based on the molar Cl/Br ratios analysis. The oxygen and hydrogen stable isotope analysis of groundwater demonstrated the mixing between the groundwater and Yellow River water. An association between lateral recharge and mixing, evaporation, leaching, vertical mixing, and arsenic enrichment in groundwater was established based on the correlation between Cl<sup>–</sup> concentration and δ<sup>18</sup>O values. In an anaerobic groundwater environment, nitrate from nitrogen fertilizers indirectly oxidized As(III) to As(V).</p> </span>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1134/s0016702924020046
Abstract
Pargasite stability was experimentally studied in IHPV at ({{P}_{{{{{text{H}}}_{{text{2}}}}{text{O}}}}}) = 2 kbar and temperatures of 1000 to 1100oC, with equilibrium approached from above and below. Calcic amphibole was used to experimentally model processes that occur in a volcanic chamber at pressures up to 5 kbar. The phase diagram of pargasite has been refined. It has been established that the stability of pargasite is controlled by three reactions. (1) At low water pressures of less than 1 kbar, the dehydration reaction Prg = Fo + Sp + Di + Ne + An + H2O proceeds. (2) At water pressures higher than 1.2–1.5 kbar and a temperature of about 1100°C, the decomposition of pargasite is controlled by its incongruent melting Prg = Fo + Sp + {Di + Ne + An}L + H2O. (3) The third reaction Prg + L = Fo + Sp + Di + {Ne + Pl}L + H2O occurs within the same pressure range as the previous one but at lower temperatures of about ~1050°C. The reaction controls the pargasite liquidus and is caused by interaction between amphibole and coexisting melt. The liquidus of pargasite seems to most strongly depend on the activity of silica ({{a}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}}) in the melt.
{"title":"Experimental Study of Pargasite NaCa2(Mg4Al)[Si6Al2O22](OH)2 Stability at T = 1000–1100°C and Pressure up to $${{P}_{{{{{text{H}}}_{{text{2}}}}{text{O}}}}}$$ = 5 Kbar","authors":"","doi":"10.1134/s0016702924020046","DOIUrl":"https://doi.org/10.1134/s0016702924020046","url":null,"abstract":"<span> <h3>Abstract</h3> <p>Pargasite stability was experimentally studied in IHPV at <span> <span>({{P}_{{{{{text{H}}}_{{text{2}}}}{text{O}}}}})</span> </span> = 2 kbar and temperatures of 1000 to 1100<sup>o</sup>C, with equilibrium approached from above and below. Calcic amphibole was used to experimentally model processes that occur in a volcanic chamber at pressures up to 5 kbar. The phase diagram of pargasite has been refined. It has been established that the stability of pargasite is controlled by three reactions. (1) At low water pressures of less than 1 kbar, the dehydration reaction <em>Prg</em> = <em>Fo</em> + <em>Sp</em> + <em>Di</em> + <em>Ne</em> + <em>An</em> + H<sub>2</sub>O proceeds. (2) At water pressures higher than 1.2–1.5 kbar and a temperature of about 1100°C, the decomposition of pargasite is controlled by its incongruent melting <em>Prg</em> = <em>Fo</em> + <em>Sp</em> + {<em>Di</em> + <em>Ne</em> + <em>An</em>}<sup><em>L</em></sup> + H<sub>2</sub>O. (3) The third reaction <em>Prg</em> + <em>L</em> = <em>Fo</em> + <em>Sp</em> + <em>Di</em> + {<em>Ne</em> + <em>Pl</em>}<sup><em>L</em></sup> + H<sub>2</sub>O occurs within the same pressure range as the previous one but at lower temperatures of about ~1050°C. The reaction controls the pargasite liquidus and is caused by interaction between amphibole and coexisting melt. The liquidus of pargasite seems to most strongly depend on the activity of silica <span> <span>({{a}_{{{text{Si}}{{{text{O}}}_{{text{2}}}}}}})</span> </span> in the melt.</p> </span>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-01DOI: 10.1134/s001670292402006x
Abstract
Atacamite, empirical formula (Cu1.97Zn0.01)Cl0.94(OH)3.02, from the paleofumaroles of the monogenic volcano of Mount 1004, Tolbachik, Kamchatka, Russia, has been studied by thermal and electron microprobe analyses, X-ray powder diffraction, IR and Raman spectroscopy, and Calvet microcalorimetry. The thermal decomposition of atacamite was studied using X-ray diffraction and IR spectroscopy. The enthalpy of formation from elements for atacamite of the theoretical composition Cu2Cl(OH)3 (−810.2 ± 7.7 kJ/mol) was determined by melt dissolution calorimetry, and the Gibbs energy of formation (−657.0 ± 7.7 kJ/mol) was calculated. The stability of atacamite in the Cu–O–Cl–H system was thermodynamically modeled based on the obtained data, and the boundaries of its stability field were calculated under conditions of high alkalinity and high acidity of the mineral-forming medium.
{"title":"Atacamite from the Paleofumaroles of Mount 1004, Tolbachik Volcano, Kamchatka: Thermodynamic Properties","authors":"","doi":"10.1134/s001670292402006x","DOIUrl":"https://doi.org/10.1134/s001670292402006x","url":null,"abstract":"<span> <h3>Abstract</h3> <p>Atacamite, empirical formula (Cu<sub>1.97</sub>Zn<sub>0.01</sub>)Cl<sub>0.94</sub>(OH)<sub>3.02</sub>, from the paleofumaroles of the monogenic volcano of Mount 1004, Tolbachik, Kamchatka, Russia, has been studied by thermal and electron microprobe analyses, X-ray powder diffraction, IR and Raman spectroscopy, and Calvet microcalorimetry. The thermal decomposition of atacamite was studied using X-ray diffraction and IR spectroscopy. The enthalpy of formation from elements for atacamite of the theoretical composition Cu<sub>2</sub>Cl(OH)<sub>3</sub> (−810.2 ± 7.7 kJ/mol) was determined by melt dissolution calorimetry, and the Gibbs energy of formation (−657.0 ± 7.7 kJ/mol) was calculated. The stability of atacamite in the Cu–O–Cl–H system was thermodynamically modeled based on the obtained data, and the boundaries of its stability field were calculated under conditions of high alkalinity and high acidity of the mineral-forming medium.</p> </span>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Bam area is located north of the Kerman magmatic copper belt (KMCB) in SE Iran. It belongs to the Urumieh-Dothtar magmatic assemblage (UDMA) that hosts many large Cu-porphyry deposits such as Sarchemeh, Iju, Meiduk, Pakram, and Dalli. The area comprises volcanic and volcano-sedimentary rocks of the Eocene intruded by some sub-volcanic patches. Geochemical analyses show that the sub-volcanic rocks are calc-alkaline granodiorites formed on an active continental margin. The rare earth elements (REE) distribution patterns are differentiated (LaN/YbN = 4–31), having weak to moderate Eu negative anomalies (Eu/Eu* = 0.4–0.8) and flat heavy rare earth element (HREE) sections. The MgO, SiO2, La, Yb, Sr, Sm, and Y contents of these rocks are consistent with adakite-like magmas formed by partial melting of thickened lower crust containing no garnet. Negative correlations of Al2O3, Y and Ba with SiO2 and moderate to weak Eu negative anomalies, indicate the role of hornblende, K-feldspar, and plagioclase fractionation in the formation of these rocks. Geochemical features of the Bam sub-volcanic rocks are similar to those of the Cu-porphyry deposits from UDMA and Malmyzh deposit from eastern Russia, indicating fertility of these rocks for Cu mineralization that should be considered in the future explorations.
{"title":"Geochemistry and Fertility Assessment of Sub-Volcanic Rocks from the Bam Area, North of the Kerman Magmatic Copper Belt, SE Iran","authors":"Mirmohammad Miri, Alireza Zarasvandi, Samaneh Razi Jalali","doi":"10.1134/s0016702924030078","DOIUrl":"https://doi.org/10.1134/s0016702924030078","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Bam area is located north of the Kerman magmatic copper belt (KMCB) in SE Iran. It belongs to the Urumieh-Dothtar magmatic assemblage (UDMA) that hosts many large Cu-porphyry deposits such as Sarchemeh, Iju, Meiduk, Pakram, and Dalli. The area comprises volcanic and volcano-sedimentary rocks of the Eocene intruded by some sub-volcanic patches. Geochemical analyses show that the sub-volcanic rocks are calc-alkaline granodiorites formed on an active continental margin. The rare earth elements (REE) distribution patterns are differentiated (La<sub>N</sub>/Yb<sub>N</sub> = 4–31), having weak to moderate Eu negative anomalies (Eu/Eu* = 0.4–0.8) and flat heavy rare earth element (HREE) sections. The MgO, SiO<sub>2</sub>, La, Yb, Sr, Sm, and Y contents of these rocks are consistent with adakite-like magmas formed by partial melting of thickened lower crust containing no garnet. Negative correlations of Al<sub>2</sub>O<sub>3</sub>, Y and Ba with SiO<sub>2</sub> and moderate to weak Eu negative anomalies, indicate the role of hornblende, K-feldspar, and plagioclase fractionation in the formation of these rocks. Geochemical features of the Bam sub-volcanic rocks are similar to those of the Cu-porphyry deposits from UDMA and Malmyzh deposit from eastern Russia, indicating fertility of these rocks for Cu mineralization that should be considered in the future explorations.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139518592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sedimentary environment can be restored qualitatively or semi-qualitatively by using elements or element combinations that are sensitive to paleoenvironment conditions. By measuring the major elements, trace elements and rare earth elements of 23 shale samples collected from coring wells in the Central Nanpanjiang Basin, we discussed the paleoenvironment conditions, including paleo-water depth, redox conditions, paleoclimate and provenance. La and Co contents indicate that the paleo-water depth in the Central Nanpanjiang Basin gradually deepened during the Late Permian. The ratios of U/Th, Uau, V/Cr, Ni/Co and V/Sc suggest that the Central Nanpanjiang Basin was in an oxic condition in the Late Permian, which was stable during the Permian Longtan and Dalong depositional periods. C-value (Climate index value) and binary diagrams of Sr/Cu and Ga/Rb show that the Central Nanpanjiang Basin was characterized by a warm and arid climate during the depositional of the Permian Longtan Formation, a warm and humid climate in the lower part of the Dalong Formation, and a warm and arid climate again in the upper part of the Dalong Formation. The chemical index of alteration (CIA), plagioclase index of alteration (PIA), index of chemical variability (ICV), and Th/U and K/Rb values can indicate the geological tectonic settings of source regions. From the Longtan period to the Dalong period, the small CIA amplitude and relatively stable ICV indicate that chemical weathering in the source area was constantly slighty weak. However, Th/U increased significantly but PIA increased slightly in the lower Dalong Formation, indicating an obvious climate change in the early deposition of the Dalong Formation. In addition, the geochemical discrimination calculation and plots show that the provenance of the studied shales was related to felsic volcanic rocks and the tectonic settings of the Upper Permian shale source areas in the Central Nanpanjiang Basin were mainly oceanic island arc and continental arc.
{"title":"Geochemical Characteristics of the Upper Permian Shales in the Central Nanpanjiang Basin: Implications for Paleoenvironment Conditions","authors":"Lijun Shen, Yifan Gu, Zhihong Wei, Dongfeng Hu, Ruobing Liu, Yuqiang Jiang, Yonghong Fu","doi":"10.1134/s001670292403008x","DOIUrl":"https://doi.org/10.1134/s001670292403008x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Sedimentary environment can be restored qualitatively or semi-qualitatively by using elements or element combinations that are sensitive to paleoenvironment conditions. By measuring the major elements, trace elements and rare earth elements of 23 shale samples collected from coring wells in the Central Nanpanjiang Basin, we discussed the paleoenvironment conditions, including paleo-water depth, redox conditions, paleoclimate and provenance. La and Co contents indicate that the paleo-water depth in the Central Nanpanjiang Basin gradually deepened during the Late Permian. The ratios of U/Th, U<sub>au</sub>, V/Cr, Ni/Co and V/Sc suggest that the Central Nanpanjiang Basin was in an oxic condition in the Late Permian, which was stable during the Permian Longtan and Dalong depositional periods. C-value (Climate index value) and binary diagrams of Sr/Cu and Ga/Rb show that the Central Nanpanjiang Basin was characterized by a warm and arid climate during the depositional of the Permian Longtan Formation, a warm and humid climate in the lower part of the Dalong Formation, and a warm and arid climate again in the upper part of the Dalong Formation. The chemical index of alteration (CIA), plagioclase index of alteration (PIA), index of chemical variability (ICV), and Th/U and K/Rb values can indicate the geological tectonic settings of source regions. From the Longtan period to the Dalong period, the small CIA amplitude and relatively stable ICV indicate that chemical weathering in the source area was constantly slighty weak. However, Th/U increased significantly but PIA increased slightly in the lower Dalong Formation, indicating an obvious climate change in the early deposition of the Dalong Formation. In addition, the geochemical discrimination calculation and plots show that the provenance of the studied shales was related to felsic volcanic rocks and the tectonic settings of the Upper Permian shale source areas in the Central Nanpanjiang Basin were mainly oceanic island arc and continental arc.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139518424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-21DOI: 10.1134/s0016702924030091
Zhi Wang, Wei Zhong, Xiaojun Wang, Yingyi Du, Tianhang Li, Jibin Xue, Mingying Quan
Abstract
Previous multi-proxy records have revealed the advantages of well-preserved and long-scale geological archives from the lake sediments of Barkol Lake, which is located at northeast Xinjiang in northwest China. However, the exact organic matter (OM) sources in the sediments and their response to climatic variability still remain unclear in this area. In this study, we present an 8.8 kyr n-alkane record extracted from the sediments in Barkol Lake to explore the OM sources and the relationship between n-alkanes and climatic changes. The results indicate that the n-alkane composition was dominated by long-chain n-alkanes(C27–C31), implying a dominant origination of OM from the terrestrial higher plants and emergent aquatic plants. The n-alkane data further revealed that changes in OM sources were related to the surface erosion-transportation-deposition processes controlled by climatic changes. Lake level changes, which are also regulated by climate conditions, played an important role in impacting OM accumulation. Relatively wetter conditions would result in a rising lake level that favored more aquatic OM and less terrestrial OM input, and vice versa. The regional climate patterns have been generally dominated by alternations of cold-wet and warm-dry episodes over the past ~8.8 kyr. We preliminarily concluded the dynamic changes of OM input and the hydrological changes in Barkol Lake was mainly controlled by SSTs in the North Atlantic region and melting water supply modulated by Eurasian ice sheet.
摘要 先前的多代志记录揭示了位于中国西北部新疆东北部的巴尔喀什湖湖泊沉积物中保存完好的长尺度地质档案的优势。然而，该地区沉积物中有机质（OM）的确切来源及其对气候变异的响应仍不清楚。在本研究中，我们展示了从巴尔喀什湖沉积物中提取的 8.8 千年正构烷烃记录，以探讨 OM 来源以及正构烷烃与气候变化之间的关系。结果表明，正构烷烃以长链正构烷烃（C27-C31）为主，这意味着OM主要来源于陆生高等植物和挺水植物。正构烷烃数据进一步表明，OM 来源的变化与受气候变化控制的地表侵蚀-运输-沉积过程有关。同样受气候条件调节的湖泊水位变化在影响 OM 积累方面发挥了重要作用。相对较湿的条件会导致湖面上升，从而有利于增加水生 OM，减少陆生 OM 的输入，反之亦然。在过去约 8.8 千年中，区域气候模式总体上以冷湿和暖干交替为主。我们初步认为，巴尔喀湖 OM 输入的动态变化和水文变化主要受北大西洋地区的 SST 和欧亚冰盖调节的融水供应控制。
{"title":"Organic Matter Source Traced by n-Alkane Records Derived from Sediments of Barkol Lake in Eastern Xinjiang (NW China) and Its Response to Moisture Variability in the Past 8800 Years","authors":"Zhi Wang, Wei Zhong, Xiaojun Wang, Yingyi Du, Tianhang Li, Jibin Xue, Mingying Quan","doi":"10.1134/s0016702924030091","DOIUrl":"https://doi.org/10.1134/s0016702924030091","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Previous multi-proxy records have revealed the advantages of well-preserved and long-scale geological archives from the lake sediments of Barkol Lake, which is located at northeast Xinjiang in northwest China. However, the exact organic matter (OM) sources in the sediments and their response to climatic variability still remain unclear in this area. In this study, we present an 8.8 kyr <i>n</i>-alkane record extracted from the sediments in Barkol Lake to explore the OM sources and the relationship between <i>n</i>-alkanes and climatic changes. The results indicate that the <i>n</i>-alkane composition was dominated by long-chain <i>n</i>-alkanes(C<sub>27</sub>–C<sub>31</sub>), implying a dominant origination of OM from the terrestrial higher plants and emergent aquatic plants. The <i>n</i>-alkane data further revealed that changes in OM sources were related to the surface erosion-transportation-deposition processes controlled by climatic changes. Lake level changes, which are also regulated by climate conditions, played an important role in impacting OM accumulation. Relatively wetter conditions would result in a rising lake level that favored more aquatic OM and less terrestrial OM input, and <i>vice versa</i>. The regional climate patterns have been generally dominated by alternations of cold-wet and warm-dry episodes over the past ~8.8 kyr. We preliminarily concluded the dynamic changes of OM input and the hydrological changes in Barkol Lake was mainly controlled by SSTs in the North Atlantic region and melting water supply modulated by Eurasian ice sheet.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139518519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1134/S0016702924010075
V. Naumov, A. Girnis, V. Dorofeeva
{"title":"Major, Volatile, Ore, and Trace Elements in Magmatic Melts in the Earth’s Dominant Geodynamic Settings. II. Similarities and Differences","authors":"V. Naumov, A. Girnis, V. Dorofeeva","doi":"10.1134/S0016702924010075","DOIUrl":"https://doi.org/10.1134/S0016702924010075","url":null,"abstract":"","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140524970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1134/S0016702924010038
E. O. Dubinina, S. А. Kossova, Y. Chizhova
{"title":"High-Precision Determination of Carbon Isotope Composition and Concentration of Dissolved Inorganic Carbon in Seawater","authors":"E. O. Dubinina, S. А. Kossova, Y. Chizhova","doi":"10.1134/S0016702924010038","DOIUrl":"https://doi.org/10.1134/S0016702924010038","url":null,"abstract":"","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140516309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-01-01DOI: 10.1134/S0016702924010026
N. M. Sushchevskya, V. D. Scherbakov, A. Peyve, E. Dubinin, B. Belyatsky, A. V. Zhilkina
{"title":"Oceanic Crust Formation within the Andrew Bain Fault Zone, Southwest Indian Ridge: Petrological and Geochemical Evidence","authors":"N. M. Sushchevskya, V. D. Scherbakov, A. Peyve, E. Dubinin, B. Belyatsky, A. V. Zhilkina","doi":"10.1134/S0016702924010026","DOIUrl":"https://doi.org/10.1134/S0016702924010026","url":null,"abstract":"","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140525887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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