Acta Geochimica最新文献

{"title":"Influence of igneous intrusions on maturation of the Cretaceous-Eocene source rocks of the offshore Tanzanian Basin","authors":"John William Gama,&nbsp;Emily Barnabas Kiswaka,&nbsp;Elisante Elisaimon Mshiu","doi":"10.1007/s11631-024-00730-1","DOIUrl":"10.1007/s11631-024-00730-1","url":null,"abstract":"<div><p>The offshore Tanzanian Basin contains numerous igneous intrusions emplaced at various stratigraphic levels. Previous studies indicate these intrusions have impacted petroleum systems, affecting key elements such as source rocks, reservoirs, seals, migration pathways, and trapping mechanisms. However, due to the limited number of wells drilled in the region, there have been few studies reporting the associated thermal effects on source rock maturation and their role in hydrocarbon generation. To gain a comprehensive understanding of the intricate relationship between intrusions and the petroleum system, particularly source rock, an integrated geochemical and resistivity log analysis was carried out. The geochemical results show that the Cretaceous-Cenozoic sediments of the study area have low total organic carbon contents (TOC &lt; 1 wt%), kerogen yield (&lt; 1 Mg HC/g), and Hydrogen Index (&lt; 100 Mg HC/g), primarily composed of Type III (gas-prone) to Type IV (inert) kerogens. These sediments have undergone varying levels of thermal maturity, ranging from post-mature (within Cretaceous), matured (in Paleocene) to immature (in Eocene) thermal states. The Cretaceous strata located proximal to the intrusions exhibit significant thermal alteration, resulting in a reduction of both organic matter (OM) content and source potential compared to the Eocene and Paleocene samples. This observation is consistent with the estimated paleotemperature (T) and resistivity log (ILD) along the depth profile, which have mapped local thermal alteration increasing from base Paleocene to Cretaceous. These findings have implications for source rock potential and thermal evolution history in the offshore Tanzanian Basin. This study highlights the necessity for thorough subsurface mapping in the area to identify both younger and older intrusive rocks. These intrusions pose a potential risk in petroleum exploration, especially when they intrude into matured source rock intervals.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"387 - 403"},"PeriodicalIF":1.4,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749053","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}

{"title":"Groundwater geochemical evolution, origin and quality in the Lower Pra Basin, Ghana: Insights from hydrogeochemistry, multivariate statistical analysis, mineral saturation indices, stable isotopes (δ2H and δ18O) and geostatistical analysis","authors":"Samuel Y. Ganyaglo,&nbsp;Joel Y. Binyiako,&nbsp;Emmanuel M. Teye,&nbsp;Abass Gibrilla,&nbsp;Dickson Abdul-Wahab,&nbsp;Samuel Edusei,&nbsp;Paulina Amponsah,&nbsp;Courage D. Egbi,&nbsp;Samuel B. Dampare,&nbsp;Ebenezer Aquisman Asare","doi":"10.1007/s11631-024-00725-y","DOIUrl":"10.1007/s11631-024-00725-y","url":null,"abstract":"<div><p>In many places across the globe, including the Wassa District of Ghana, groundwater provides a significant supply of water for various purposes. Understanding the groundwater origin and hydrogeochemical processes controlling the groundwater chemistry is a major step in the sustainable management of the aquifers. A total of 29 groundwater samples were collected and analysed. Ionic ratio graphs, multivariate statistical analysis, mineral saturation indices, stable isotopes, and geostatistics methods were used to examine the sources and the quality of the groundwater. The findings describe the water types in the district as Ca–Mg–HCO₃–Cl, Ca–Na–HCO₃, Na–Ca–HCO₃, Ca–Na–HCO₃–Cl, Na–Ca–HCO₃–Cl, mix water type, Na–HCO₃–Cl, with possible evolution to Ca–Na–Cl–HCO₃, and Na–Ca–Cl–HCO₃. According to the IEWQI for drinking water, around 53.6% of the samples have good quality, whereas 10.7% have very low-quality groundwater. Only 3.45% of the samples are suitable to use for irrigation without treatment, whereas 41.4% are somewhat safe with minimal treatment. Water-rock interactions, including the dissolution and weathering of silicate minerals, cation exchange processes, and human activities like mining and quarrying, are some of the main factors influencing groundwater chemistry. Principal component analysis revealed that groundwater chemistry is influenced by a combination of natural and anthropogenic sources. The APCs-MLR receptor model quantifies the factors that play important roles in groundwater salinization, including mineral dissolution and weathering (19.4%), localised Cd (16%), Ni (14.6%), Pb (12.8%), and Fe (11.4%) contamination from urbanisation while unidentified sources of pollution account for about 26.0%. The stable isotopes revealed groundwater is of meteoric origin and water-rock interaction the major mechanism for groundwater mineralization. The results of this research highlight the need of implementing an integrated strategy for managing and accessing groundwater quality.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"348 - 372"},"PeriodicalIF":1.4,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143749076","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}

{"title":"Ore-forming mechanism of Huxu Au-dominated polymetallic deposit in the Dongxiang Basin, South China: Constraints from in-situ trace elements and S–Pb isotopes of pyrite","authors":"Hongze Gao,&nbsp;Jiajie Chen,&nbsp;Chengbiao Leng,&nbsp;Yuhui Hu,&nbsp;Huidan Xie,&nbsp;Zenghua Li","doi":"10.1007/s11631-024-00726-x","DOIUrl":"10.1007/s11631-024-00726-x","url":null,"abstract":"<div><p>The Huxu Au-dominated polymetallic deposit is a hydrothermal deposit located in the Dongxiang volcanic basin in the middle section of the Gan-Hang tectonic belt in South China. The orebodies primarily occur within the Jurassic-Cretaceous quartz diorite porphyry, while the genesis of this deposit is unclear. This study focused on geological and mineralogical characteristics, <i>in-situ</i> trace elements and S-Pb isotopes of three generations of pyrite of the Huxu deposit to clarify the distribution of trace elements in pyrite, ore-forming fluid and material sources, and genetic types of the deposit. The mineralization stage of the deposit can be divided into quartz-pyrite stage (S1), quartz-pyrite-hematite stage (S2), quartz-polymetallic sulfide stage (S3) and quartz-hematite stage (S4), with the corresponding pyrite being divided into three generations (Py1–Py3). <i>in-situ</i> trace element data of pyrite show that Au in pyrite mainly exists in the form of solid solution (Au⁺), and the content is relatively low at all stages (0.18 ppm for Py1, 0.32 ppm for Py2, 0.68 ppm for Py3), while Pb and Zn mainly exist as sulfide inclusions in the pyrite. S-Pb isotopes show that the sulfur and ore-forming material of this deposit are mainly sourced from magma. The mineral association, mineral textures and trace elements in different stages of pyrite indicate that fluid boiling and fluid mixing are the key factors of native gold precipitation in S2 and S4, respectively, while water-rock interaction controlled the precipitation of Pb-Zn sulfides. These integrating with geological characteristics suggests that the deposit should be an intermediate sulfidation epithermal deposit.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 6","pages":"1223 - 1240"},"PeriodicalIF":1.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664464","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}

{"title":"Geological studies and thermal treatment of some Paleogene deposits in east Beni Suef region, Egypt","authors":"Alaa T. A. Amin,&nbsp;Ahmed M. El-Mezayen,&nbsp;Darweesh M. Elkholy,&nbsp;Hossam A. Khamis,&nbsp;Hazem K. A. Sarhan","doi":"10.1007/s11631-024-00720-3","DOIUrl":"10.1007/s11631-024-00720-3","url":null,"abstract":"<div><p>Geological setting, facies characteristics, and geochemistry, including TGA (thermo-gravimetric analysis) of Paleogene deposits in east Beni Suef region (Egypt), were studied in the present work. Lithostratigraphically, the area consists of three rock units, arranged from oldest to youngest: Tarbul Member of Beni Suef Formation (Middle-Late Eocene), Maadi Formation (Late Eocene), and Gebel Ahmar Formation (Oligocene), this last formation registered for the first time in the east of Beni Suef area (Egypt). Seven microfacies types (F1–F7) were determined by the microscopic examination of the studied samples in low- to high-energy and shallow-subtidal marine conditions. The lithostratigraphic, petrological, and geochemical results revealed that the Eocene succession in the present area is composed mainly of carbonates as well as siliciclastics. The Oligocene Gebel Ahmar Formation consists mainly of silica and iron oxides. The enrichment of the rock units with iron oxides in the studied area, as well as the high proportions of trace elements such as Zr, Ba, V, and Sr, in particular in the Gebel Ahmar Formation, reflects the influence of the hydrothermal solutions during the Oligocene. TGA, which monitors weight changes during heating at a constant rate, was used to determine the thermal stability and volatile component content of the materials. The ferruginous sandstone of Gebel Ahmar Formation exhibits various decomposition phases when exposed to thermal influences, with TGA indicating an initial mass decrease starting at 61.8 °C. In contrast, the ferruginous limestone of the Maadi Formation shows a single-phase mass decrease between 650 and 875 °C.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"278 - 296"},"PeriodicalIF":1.4,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807901","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}

{"title":"Multiple-stage W mineralization in the Guanfang W deposit, southeastern Yunnan Province, China: Insights from scheelite in-situ trace elemental and Sr isotopic analyses","authors":"Bin Sun,&nbsp;Yi Liu,&nbsp;Zhigang Kong,&nbsp;Xuelong Liu,&nbsp;Xiaojun Jiang,&nbsp;Chao Li,&nbsp;Wenchang Li","doi":"10.1007/s11631-024-00722-1","DOIUrl":"10.1007/s11631-024-00722-1","url":null,"abstract":"<div><p>The Guanfang large-scale W deposit is located in the W polymetallic ore concentration area of Bozhushan in southeastern Yunnan, China. Despite extensive research, the fluid evolution process of the deposit remains ambiguous, leading to controversy regarding its genesis. This study conducted a detailed field geological survey, with systematic sampling of the KT6 orebody, to delineate mineralization stages. Fine mineralogy work, including the use of CL images of scheelite, <i>in-situ</i> LA-ICP-MS trace elements, and Sr isotopes, was carried out on different generations of scheelite formed in various stages. The findings identified the evolution of fluids in the mineralization process, shedding light on the genesis of the deposit. The study revealed four mineralization stages at the Guanfang W deposit: prograde skarn stage, retrograde skarn stage, quartz-sulfide stage, and carbonate-fluorite stage. Different generations of scheelite (Sch I, Sch II, Sch III) were observed in the first three stages, displaying distinct chondrite-normalized REE patterns. The REE of Sch I mainly substituted into the Ca site by REE³⁺  + □_Ca, and there may be a similar substitution of Nb for REE, whereas it is not the main substitution method. The REE of Sch II mainly enter the scheelite lattice in the form of REE³⁺  + Na⁺, and there may be a substitution of Nb for REE isomorphism. In the early stage, The REE of Sch III was mainly replaced by Nb for REE isomorphism, while in the later stage, the replacement mode of REE³⁺  +  □_Ca coexisted with it. The Mo content in scheelite, along with the corresponding Eu anomalies in both scheelite and garnet, collectively imply that the ore-forming fluids during various mineralization stages were predominantly oxidizing, with only slight reducibility observed in Sch II. The in-situ Sr isotope ratios of scheelite concentrates ranged from 0.7093 to 0.7153, resembling those of the Bozhushan granite, indicating a relationship between W mineralization and granite. In addition, the Y/Ho ratios of scheelite from various mineralization stages exhibit a narrow range (19–31), with a pronounced correlation between the contents of Y and Ho and a similar trend in their variation. This consistency suggests that the Guanfang deposit has undergone a uniform or comparable evolutionary process, implying a stable ore-forming fluid across different mineralization stages.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"112 - 127"},"PeriodicalIF":1.4,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141808792","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}

{"title":"Alkaline igneous rocks, a potential source of rare metals and radioactive minerals: Case study at Amreit area, south Eastern Desert, Egypt","authors":"Baaha M. Emad","doi":"10.1007/s11631-024-00713-2","DOIUrl":"10.1007/s11631-024-00713-2","url":null,"abstract":"<div><p>Alkaline igneous rocks represent one of the most economically important resources of radioactive minerals and rare metals. New field observations and petrographic studies are integrated with whole-rock geochemical analyses and Gamma ray spectroscopy data of alkaline rocks associated with the Amreit complex. The fieldwork was achieved by the collection of more than forty samples from alkaline granites and alkaline syenites. The youngest rocks cropping out in the study area are the cogenetic alkaline rocks, ranging from alkaline granite to alkaline syenite. These alkaline rocks are composed essentially of K-feldspar, alkali amphiboles (arfvedsonite), and sodic pyroxene, with accessories such as zircon, apatite, and ilmenite. Mineral characterization of the highly radioactive zones in both alkaline granite and alkaline syenite displays enrichment in monazite, thorite, zircon, ferro-columbite, xenotime, and allanite minerals. Geochemical analyses indicate that the Amreit rocks are alkaline with peralkaline affinity and have high concentrations of total alkalis (K₂O + Na₂O), large ion lithophile elements (LILEs; Ba and Rb), high field strength elements (HFSEs; Y, Zr and Nb), rare earth elements (REEs) and significantly depleted in K, Sr, P, Ti, and Eu, typically of post-collision A-type granites. Typically, the Amreit alkaline igneous rocks are classified as within plate granites and display A2 subtype characteristics. The fractionation of K-feldspars played a distinctive role during the magmatic evolution of these alkaline rocks. The geochemical characteristics indicate that the studied alkaline igneous rocks which were originated by fractional crystallization of alkaline magmas were responsible for the enrichment of the REE and rare metals in the residual melt. The high radioactivity is essentially related to accessory minerals, such as zircon, allanite, and monazite. The alkaline granite is the most U- and Th-rich rock, where radioactivity level reaches up to 14.7 ppm (181.55 Bq/kg) eU, 40.6 ppm (164.84 Bq/kg) eTh, whereas in alkaline syenite radioactivity level is 8.5 ppm (104.96 Bq/kg) eU, 30.2 ppm (122.61 Bq/kg) eTh. These observations suppose that these alkaline rocks may be important targets for REEs and radioactive mineral exploration.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"189 - 214"},"PeriodicalIF":1.4,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141826135","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}

{"title":"Biogeochemical behavior of 210Po in the aquatic ecosystem of the North Crimean Canal and adjacent irrigated soils","authors":"A. A. Korotkov,&nbsp;N. Yu. Mirzoeva,&nbsp;O. N. Miroshnichenko,&nbsp;I. N. Moseichenko","doi":"10.1007/s11631-024-00721-2","DOIUrl":"10.1007/s11631-024-00721-2","url":null,"abstract":"<div><p>The main objectives of this study were to investigate the distribution features of the ²¹⁰Po in abiotic (water and bottom sediments) and biotic (zooplankton, mollusks, fish) components of the North Crimean Canal (NCC) aquatic ecosystem and adjacent irrigated soils as well as assessment of the doses received by water organisms from α-radiation of absorbed ²¹⁰Po. The samples were processed using standard radiochemical methods accepted in international practice. The activity of ²¹⁰Po in the samples was measured using the alpha-spectrometric OCTETE Plus complex (ORTEC-AMETEK, USA). The measurement error did not exceed 20%. Activity concentration of ²¹⁰Po in the studied objects decreased in the following rank: suspended matter (73.6 Bq/kg d.w.) &gt; soils (32.5 Bq/kg d.w.) ≈ bottom sediments (32.1 Bq/kg d.w.) &gt; mollusks (23.4 Bq/kg w.w.) &gt; fish (6.4 Bq/kg w.w.). The ²¹⁰Po distribution coefficient (<i>K</i>_d) values in water between suspended matter and its dissolved parts varied within the 1.4 × 10⁴–1.4 × 10⁵ L/kg range. The concentration factors (CF) of ²¹⁰Po for hydrobionts of the NCC were in the range 10³–10⁴ L/kg. The calculated absorbed radiation doses from ²¹⁰Po alpha radiation for the hydrobionts of the North Crimean Canal were significantly below the recommended dose limits.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"314 - 324"},"PeriodicalIF":1.4,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141640292","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}

{"title":"The lithology and composition of lunar mantle modified by ilmenite bearing cumulate: A thermodynamic model","authors":"Wei Huang,&nbsp;Wei Du","doi":"10.1007/s11631-024-00718-x","DOIUrl":"10.1007/s11631-024-00718-x","url":null,"abstract":"<div><p>Due to their high density, the ilmenite-bearing cumulates (IBC) (with or without KREEP) formed during the late-stage lunar magma ocean solidification are thought to sink into the underlying lunar mantle and trigger lunar mantle overturn. Geophysical evidence implied that IBC may descend deep inside the Moon and remain as a partially molten layer at the core-mantle boundary (CMB). However, partial melting may have occurred on the mixed mantle cumulates during the sinking of IBC/KREEP and the silicate melt may be positively buoyant, thus preventing the IBC/KREEP layer from sinking to the CMB. Here, we perform thermodynamic simulation on the stability of lunar mantle cumulates at different depths mixed with different amounts of IBC/KREEP from an updated LMO model. The modeling results suggest that the sinking of IBC/KREEP will cause at least 5 wt% partial melting in the shallow (~ 120 km) and a much larger degree of partial melting in the deep lunar mantle (~ 420 km). Due to the density contrast with the surrounding mantle, IBC/KREEP-bearing melts could potentially decouple under certain conditions. The modified lunar mantle by sinking of IBC/KREEP can better explain the formation of different kinds of lunar basaltic magma than the primary lunar mantle formed through differentiation of lunar magma ocean. Sinking of IBC/KREEP back into the lunar mantle may introduce plagioclase, clinopyroxene, garnet, and incompatible radioactive elements into the deep lunar mantle, which will further affect the thermal and chemical evolution of the lunar interior.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 5","pages":"856 - 875"},"PeriodicalIF":1.4,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141654823","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}

{"title":"Features of the spatial and seasonal distribution of hydrocarbons in water of the North Crimean Canal, Crimea","authors":"O. V. Soloveva,&nbsp;E. A. Tikhonova,&nbsp;N. Yu. Mirzoeva","doi":"10.1007/s11631-024-00719-w","DOIUrl":"10.1007/s11631-024-00719-w","url":null,"abstract":"<div><p>The North Crimean Canal is a watercourse originating from the Kakhovka Reservoir and flowing into the Crimean Peninsula. The canal is an important source of drinking water supply and is also used to irrigate agricultural lands and fill fish farms. Due to its location, in recent years its functioning has not been stable, and the processes occurring along the canal have been poorly studied. In this study, we determined the content (with a safety assessment), features of spatial and seasonal distribution, and potential sources of hydrocarbons in the water of the North Crimean Canal, Crimea. During the study period (from March to November 2023) in the primary canal, the content of aliphatic hydrocarbons did not exceed sanitary standards (0.05 mg·L⁻¹). Their increased concentrations in the secondary canals could be associated with the input of organic substances into the canal water as it moves across the Crimean Peninsula. The composition of <i>n-</i>alkanes had temporal and spatial variability. In the period from spring to autumn, the content of autochthonous compounds decreased sharply. The share of allochthonous compounds increased as a consequence of the natural processes. The analysis of biogeochemical markers showed that autochthonous compounds produced by phytoplankton predominated in the spring–summer period. Subsequently, they had less importance, and the main share was accounted for allochthonous <i>n-</i>alkanes.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 2","pages":"247 - 259"},"PeriodicalIF":1.4,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141656572","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}

{"title":"Geochemistry and petrogenesis of magnesian high-K granitoids from Bundelkhand Craton, Central India: New insights into crustal evolution","authors":"Shailendra K. Prajapati,&nbsp;Meraj Alam,&nbsp;Parashar Mishra,&nbsp;Hemant Kumar","doi":"10.1007/s11631-024-00717-y","DOIUrl":"10.1007/s11631-024-00717-y","url":null,"abstract":"<div><h3>Background</h3><p>The Bundelkhand Craton is significant for preserving the multiphase granitoids magmatism from Paleoarchean to Neoarchean periods. It consists of a variety of granite rocks, including TTGs, sanukitoids, and high-K granitoids. This study presents geochemical characteristics of high-silica (68.97 wt.%–73.99 wt.%), low-silica (58.73 wt.%–69.94 wt.%), and high K₂O (2.77 wt.%–6.16 wt.%) contents of granitoids.</p><h3>Objective</h3><p>The data on Bundelkhand Craton's granitic magmatism and geodynamics is not sufficiently robust. Geochemical data from this study will be used to further understand the origin, source, and petrogenesis of granitoid rocks and their implications for the evolution of geodynamics.</p><h3>Methodology</h3><p>Twenty-one samples were collected and analyzed for major, trace, and REE elements. Major elements were measured using X-ray fluorescence spectrometry (XRF), and trace and REE elements were analyzed by ICP-MS. Standard procedures from the Geological Survey of India were followed.</p><h3>Results</h3><p>The geochemical analysis presents high-silica (68.97-73.99 wt. %), low-silica (58.73-69.94 wt. %), and high K2O (2.77-6.16 wt. %) contents in granitoids, classified as granite-granodiorite. The rocks are calcic to calcalkalic, magnesian, and range from peraluminous to metaluminous composition. REE patterns showed strong LREE enrichment relative to HREEs, with prominent negative Eu anomalies corresponding to earlier plagioclase fractionation. Multi-element patterns revealed negative anomalies in Nb, Sr, P, and Ti and positive anomalies in Pb.</p><h3>Conclusion</h3><p>The geochemical signatures attributed to the post-collisional magma generation and continental crustal contamination. The studied rocks show A-type and A2-type lineage, suggesting they originated from the melting of continental crust during transitional/post-collisional tectonic activity. The formation of hybrid granitoids in the Bundelkhand Craton is connected to the fractionation of hybrid magmas in shallow-seated magma chambers during these tectonic processes.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"44 1","pages":"36 - 58"},"PeriodicalIF":1.4,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141661514","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}