Applied Geochemistry最新文献

{"title":"Fluid geochemical constraints on the geological genesis of carbonate geothermal systems: A case study of Quzhuomu in southern Tibet, China","authors":"Hongjie Shi ,&nbsp;Mingliang Liu ,&nbsp;Xing Wei ,&nbsp;Ke Wang ,&nbsp;Lizhen Huang ,&nbsp;Yuanyuan Cao ,&nbsp;Yanlong Kong","doi":"10.1016/j.apgeochem.2024.106222","DOIUrl":"10.1016/j.apgeochem.2024.106222","url":null,"abstract":"<div><div>The southern Tibet in China is characterized by the widespread distribution of high-temperature geothermal systems that possess significant potential for development and utilization. However, current studies in this area have been predominantly focused on geothermal systems with felsic rock reservoirs, while studies on geothermal systems with carbonate reservoirs are scarce. Thus, the large-scale exploitation of such geothermal resources remains limited. In this study, we selected the typical carbonate geothermal system of Quzhuomu in southern Tibet as the research object. Based on the hydrochemical and isotopic (δD, δ¹⁸O, δ¹³C, δ³⁴S, and δ¹¹B) characteristics of the geothermal water, we investigated the geochemical origin of Quzhuomu geothermal water, evaluated the reservoir temperature of the geothermal system, identified its heat source, and ultimately proposed a genetic mechanism for the geothermal system. The chemical components of the geothermal water showed that it primarily originated from the dissolution of marine carbonate rocks and tourmaline granite. Further, an improved mineral assemblage geothermometer showed that the reservoir temperature varied in the range 118–150 °C (mean, 128 °C). Comparative analysis between a typical magmatic geothermal system, the Gudui system, which is also located in the Sangri–Cuona rift zone, and the Quzhuomu system revealed that the strong surface geothermal manifestations and high reservoir temperature in Quzhuomu are closely related to a deep-seated magma chamber. However, the hydrochemical composition of the Quzhuomu geothermal water is not influenced by the magmatic fluids differentiated from the magma. These findings are of great significance with respect to the scientific and rational utilization of geothermal resources in the Quzhuomu geothermal field as they provide valuable insights for estimating the reservoir temperature of carbonate geothermal systems like the Quzhuomu system and investigating their genetic mechanisms.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"177 ","pages":"Article 106222"},"PeriodicalIF":3.1,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding water–rock interaction in crystalline shield fluids using calcium isotopes","authors":"Myles Schulz,&nbsp;W.R. Michael Makahnouk,&nbsp;Shaun K. Frape,&nbsp;Randy L. Stotler,&nbsp;Chris Yakymchuk","doi":"10.1016/j.apgeochem.2024.106220","DOIUrl":"10.1016/j.apgeochem.2024.106220","url":null,"abstract":"<div><div>Calcium isotopes provide a potentially robust tool for understanding the evolution of crystalline shield fluids, but previous applications have focused on near surface groundwaters. The tendency of Ca isotopes to be affected by mass-dependent fractionation during processes such as water–rock interaction provides a powerful tool for studying the evolution and origin of groundwaters hosted in crystalline rocks. We report Ca isotope ratios (δ^44/40Ca) of deep fluids (&gt;300 m) from across the Canadian Shield and integrate these with Sr and Br isotope values to understand long-term fluid–rock interactions in crystalline shield environments. Ca isotope ratios have a wide range of values from 0.07‰ to 0.86‰. At individual sites, δ^44/40Ca values are variable whereas ⁸⁷Sr/⁸⁶Sr ratios are relatively constant. Sr isotope ratios (⁸⁷Sr/⁸⁶Sr) have a negative relationship with the Ca vs. Na content of the fluid indicating different host-minerals contributing Sr to the fluid. Ca isotope fractionation was caused by metamorphic reactions and by the growth and dissolution of Ca-rich fracture-filling minerals. The δ^44/40Ca signatures of these processes are overprinted by radiogenic ingrowth of ⁴⁰Ca by decay of ⁴⁰K, which is expected to affect older and more K-rich rocks. At one site, δ^44/40Ca and δ⁸¹Br variability reflects gas-generating reactions in the fluid and/or water–rock interaction processes. These new results demonstrate the strength of combining multiple isotope analysis to elucidate the sources of groundwater salinity and decipher the complex long-term processes that occur in crystalline shield environments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"177 ","pages":"Article 106220"},"PeriodicalIF":3.1,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rare earth element patterns in sediments from the Great Lakes basin","authors":"Tassiane P. Junqueira ,&nbsp;Anna L. Harrison ,&nbsp;Matthew I. Leybourne ,&nbsp;Bas Vriens","doi":"10.1016/j.apgeochem.2024.106218","DOIUrl":"10.1016/j.apgeochem.2024.106218","url":null,"abstract":"<div><div>This study presents a comprehensive analysis of rare earth element (REE) concentrations in &gt;100 sediment samples from Lakes Erie and Huron, two of the North American Great Lakes. Significant intra- and inter-lake variability in REE concentrations is observed for both lakes Erie and Huron (&lt;10 μg/g &lt; versus &lt;6 mg/g ƩREE, respectively). Light (L) REE were enriched over heavy (H) REE in surface sediment samples across both lakes, particularly in the North Channel of Lake Huron. Sediment cores from both lakes contained REE concentrations that are equally variable over time and correlated with major elements and other trace metals, reflective of the strong control of sediment accumulation rates on REE concentrations. Sequential extractions show that REE are predominantly associated with the residual (silicate) fraction (&gt;50%) and likely originated from geogenic sources (basin weathering). However, considerable REE fractions (up to 16%) were also associated with oxide, phosphate minerals and organic/reducible material, particularly for the LREE. We attribute this apportionment and LREE enrichment to aqueous complexation and export from the water column. Finally, REE normalization and pattern-fitting reveal positive Ce anomalies (up to 16.2) in specific locations that could be indicative of hypolimnic redox gradients, whereas minor Gd and Eu anomalies (0.9 for Eu, and 1.02 for Gd, on average) likely relate to the parent rock signature. Our findings contribute valuable baseline data and insights into the complex interplay of geological, hydrodynamic, and environmental factors influencing REE distribution patterns in these lake sediments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"176 ","pages":"Article 106218"},"PeriodicalIF":3.1,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sedimentary geochemistry in P-limited freshwater drained marshes (Charente-Maritime, France): Original drivers for phosphorus mobilization","authors":"Raphaël Moncelon ,&nbsp;Christine Dupuy ,&nbsp;Philippe Pineau ,&nbsp;Claire Emery ,&nbsp;Eric Bénéteau ,&nbsp;Olivier Philippine ,&nbsp;François-Xavier Robin ,&nbsp;Edouard Metzger","doi":"10.1016/j.apgeochem.2024.106200","DOIUrl":"10.1016/j.apgeochem.2024.106200","url":null,"abstract":"<div><div>Phosphorus bioavailability is a major issue in aquatic environments, where it generally limits primary production. In this work, the analysis of the pore water and the solid phase of the sediment was carried out over a 9-month monitoring period between February 2020 and April 2021 in two drained marshes (Marans and Genouillé, France) distinct by their uses and management tools. Soluble reactive phosphorus (SRP) enrichment in the sediment was intimately controlled by iron oxide dissolution. The latter seemed highly controlled by seasonal nitrate inputs (winter and early spring) that favoured denitrification as a major benthic mineralization process promoting iron curtain development and stability. Following benthic mitigation of nitrate other anaerobic metabolisms developed such as iron dissolutive reduction promoting P recycling and planktic bioavailability. Surprisingly, sulphur cycle seemed to affect P dynamics, especially in the absence of nitrate. The absence of NO₃⁻ triggered high sulphate reduction rates in the two first centimeters depth, reaching −8.9 E⁻⁰³ ± 0.5 E⁻⁰³ and -5.0 E⁻⁰³ ± 0.2 E⁻⁰³ nmol cm⁻³ s⁻¹ in August and July at Marans and Genouillé respectively. These values placed this process at higher rates than the denitrification (maximum in May at Marans with −5.0 E⁻⁰³ ± 1.1 E⁻⁰³ nmol cm⁻³ s⁻¹) and reduced iron production (maximum in July at Genouillé with 0.5 E⁻⁰³ ± 0.1 E⁻⁰³ nmol cm⁻³ s⁻¹). The rapidity with which process changes occur (monthly scale) testified to the dynamism of these systems. The similarity in geochemical patterns regarding NO₃⁻ pressure at both sites underlines the importance of diffuse pollution in coastal systems for nitrogen mitigation and phosphorus trapping. The results obtained in this study could lead to the development of a generalized diagenetic operating model for temperate systems with high agricultural pressure. This would enable to target management efforts to both optimize the purification function and limit eutrophication risks in these systems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"176 ","pages":"Article 106200"},"PeriodicalIF":3.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}