Acta Geochimica最新文献

{"title":"A geochemical perspective on the genesis of Cenozoic basic volcanism in northeastern Turkey: an overview of metasomatism and heterogeneity of the sub-continental lithospheric mantle in a post-collisional setting","authors":"Mehmet Arslan,&nbsp;İrfan Temizel","doi":"10.1007/s11631-023-00659-x","DOIUrl":"10.1007/s11631-023-00659-x","url":null,"abstract":"<div><p>The post-collisional Cenozoic basic volcanic rocks in NE Turkey show temporal variations in whole-rock lithophile element and highly siderophile element (HSE) systematics that are mainly associated with the nature of sub-continental lithospheric mantle (SCLM) sources and parental melt generation. So far, the traditional whole-rock lithophile geochemical data of these basic volcanic rocks have provided important constraints on the nature of SCLM sources. Integrated lithophile element and HSE geochemical data of these basic volcanic rocks also reveal the heterogeneity of the SCLM source, which is principally related to variable metasomatism resulting from previous subduction(s) and post-collisional mantle-crust interactions in an extensional setting. Lithophile element geochemical features suggest that the parental magmas have derived from metasomatized spinel- to garnet-bearing SCLM sources for Eocene and Miocene basic volcanic rocks with subduction signatures whereas originated from spinel- to garnet-bearing SCLM sources for Mio-Pliocene and Plio-Quaternary basaltic volcanic rocks without the subduction signature. Lithophile element and HSE geochemistry also reveal that Eocene and Miocene basic volcanic rocks were affected by more pronounced crustal contamination than the basaltic volcanic rocks of Mio-Pliocene and Quaternary. Furthermore, the integrated lithophile element and HSE compositions of these basic volcanic rocks, together with the regional asymmetric lithospheric delamination model, reveal that the compositional variation (especially due to metasomatism) was significant temporally in the heterogeneity of the SCLM sources from which parental magmas formed during the Cenozoic era.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 3","pages":"489 - 506"},"PeriodicalIF":1.4,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138976465","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 depositional environment of fuchsite quartzites from Sargur Group, western Dharwar Craton, India","authors":"C. S. Sindhuja,&nbsp;G. Harshitha,&nbsp;C. Manikyamba,&nbsp;K. S. V. Subramanyam","doi":"10.1007/s11631-023-00661-3","DOIUrl":"10.1007/s11631-023-00661-3","url":null,"abstract":"<div><p>Meso-Neoarchean fuchsite quartzites are present in different stratigraphic positions of Dharwar Craton including the oldest (~ 3.3 Ga) Sargur Group of western Dharwar Craton. The present study deals with the petrographic and geochemical characteristics of the fuchsite quartzites from the Ghattihosahalli belt to evaluate their genesis, depositional setting and the enigma involved in the ancient sedimentation history. Their major mineral assemblages include quartz, fuchsite, and feldspars along with accessory kyanite and rutile. The geochemical compositions are characterized by high SiO₂, Al₂O₃, low MgO, CaO, strongly enriched Cr (1326–6899 ppm), Ba (1165–3653 ppm), Sr (46–210 ppm), V (107–868 ppm) and Zn (11–158 ppm) contents compared to the upper continental crust (UCC). The UCC normalized rare earth element (REE) patterns are characterized by depleted light REE [(La/Sm)_UCC = 0.33–0.95] compared to heavy REE [(Gd/Yb)_UCC = 0.42– 1.65)] with conspicuous positive Eu-anomalies (Eu/Eu* = 1.35–18.27) characteristic of hydrothermal solutions evidenced through the interlayered barites. The overall major and trace element systematics reflect a combined mafic-felsic provenance and suggest their deposition at a passive continental margin environment. The comprehensive field, petrographic, and geochemical studies indicate that these quartzites are infiltrated by Cr-rich fluids released during high-grade metamorphism of associated ultramafic rocks. The Sargur and the subsequent Dharwar orogeny amalgamated diverse lithounits from different tectonic settings, possibly leading to the release of Cr-rich fluids and the formation of fuchsite quartzite during or after the orogeny. These findings suggest a pre-existing stable crust prior to the Sargur Group and the link between orogenic events and various mineral deposits in the Dharwar Craton.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 3","pages":"555 - 570"},"PeriodicalIF":1.4,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139003572","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":"Metallogenesis of the Baidi Au-Sb deposit, southwest Guizhou Province, China: mineralogical and geochemical evidence from sulfur-bearing minerals","authors":"Jun Yan,&nbsp;Yong Xia,&nbsp;Qinping Tan,&nbsp;Zhuojun Xie,&nbsp;Guosong Ji","doi":"10.1007/s11631-023-00653-3","DOIUrl":"10.1007/s11631-023-00653-3","url":null,"abstract":"<div><p>The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou Province, China. Previous studies have focused on individual ores, but have not combined them to identify their paragenetic mechanism or metallogenic regularity. Therefore, we used field investigations, microscopic observations, and in situ analyses to identify the spatial distribution, mineral paragenesis, compositional evolution, and metallogenic material sources of the ore bodies. We also determined the Au and Sb paragenetic characteristics and the metallogenesis of the deposit. The main Au-bearing minerals in the deposit were early (Apy1–2) and late (Apy3) stage arsenopyrites, as well as pre-mineralization (Py1), mineralization (Py2–5), and late mineralization (Py6–7) stage pyrites. The main Sb-bearing minerals were stibnite (Snt), skinnerite, bournonite, and valentinite. The minerals formed in the order of Py1, Py2–3 + Apy1, Py4–5 + Apy2, Snt, and Py6–7 + Apy3. The δ³⁴S values of the arsenopyrites and pyrites ranged from − 5 to 5‰, while those of stibnite were mostly less than − 5‰ in the later mineralization stages. Sulfur was provided by deep magmatic hydrothermal fluids, but sedimentary sulfur was added in the later stages. Moreover, the trace elemental contents fluctuated and eventually became similar to those of the sedimentary strata. By comprehensively considering the ores along with the geological characteristics of the deposit, we determined that deep magma provided the Au during ore formation. Later tectonic changes provided Sb from the sedimentary strata, which precipitated along fault expansion areas and produced Au and Sb paragenesis.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"199 - 213"},"PeriodicalIF":1.4,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138977088","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":"Provenance and depositional setting of the Late Miocene- Pleistocene clastic sediments in the eastern Arabian Peninsula and western Iraq using rare earth elements geochemistry","authors":"Salih M. Awadh,&nbsp;Zinah S. Al-Ankaz,&nbsp;Mohanad R. A. Al-Owaidi,&nbsp;John S. Armstrong-Altrin","doi":"10.1007/s11631-023-00658-y","DOIUrl":"10.1007/s11631-023-00658-y","url":null,"abstract":"<div><p>The sandstones of the Late miocene–Pliocene Dibdibba Formation in the Najaf–Karbala Plateau and Basra were examined to determine their source rocks and origin. The rare earth elements (REE) and trace elements (Sc, Co, V, and Th) concentrations in these sandstones revealed that they likely derived from a single source. The steep light rare earth elements (LREE) and flat, heavy rare earth element (HREE) patterns, negative Eu anomaly, and high ΣREE contents in sandstones suggest its derivation from a suggests that a passive continental margin environment and originated from felsic source rocks. The average concentration of ΣREE is 93.5 ppm, which is lower than that of the average crustal compositions like Upper Continental Crust and Post Archean Australian Shale. The higher proportion of LREE compared to HREE implies that these sandstones were recycled and derived from a distal source. The Th/Co, Th/Sc, La/Sc, La/Co, Eu/Eu* and (La/Lu)cn elemental ratios indicated that these Late Miocene–Pliocene sandstones were derived from felsic rocks located in the marginal region of the Arabian Shield.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"399 - 410"},"PeriodicalIF":1.4,"publicationDate":"2023-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138586011","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, mineral paragenesis and geothermal conditions of oreforming fluids from the Ain El Bey Cu–Fe deposit: potential occurrence of native gold and precious metal traces (North African orogenic belt, Northern Tunisia)","authors":"Rania Ben Aissa,&nbsp;Wiem Ben Aissa,&nbsp;Said Tlig,&nbsp;Lassaâd Ben Aissa,&nbsp;Abdessalem Ben Haj Amara","doi":"10.1007/s11631-023-00657-z","DOIUrl":"10.1007/s11631-023-00657-z","url":null,"abstract":"<div><p>The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petro-mineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope—Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores (tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 °C for phase III, from 254 to 350 °C for phase IV, and from 200 to 300 °C for phases V and VI. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature (&lt; 200 °C) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"366 - 384"},"PeriodicalIF":1.4,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138620009","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":"Assessment of groundwater quantity, quality, and associated health risk of the Tano river basin, Ghana","authors":"Adwoba Kua-Manza Edjah,&nbsp;Bruce Banoeng-Yakubo,&nbsp;Anthony Ewusi,&nbsp;Enoch Sakyi-Yeboah,&nbsp;David Saka,&nbsp;Clara Turetta,&nbsp;Giulio Cozzi,&nbsp;David Atta-Peters,&nbsp;Larry Pax Chegbeleh","doi":"10.1007/s11631-023-00656-0","DOIUrl":"10.1007/s11631-023-00656-0","url":null,"abstract":"<div><p>In the Tano River Basin, groundwater serves as a crucial resource; however, its quantity and quality with regard to trace elements and microbiological loadings remain poorly understood due to the lack of groundwater logs and limited water research. This study presents a comprehensive analysis of the Tano River Basin, focusing on three key objectives. First, it investigated the aquifer hydraulic parameters and the results showed significant spatial variations in borehole depths, yields, transmissivity, hydraulic conductivity, and specific capacity. Deeper boreholes were concentrated in the northeastern and southeastern zones, while geological formations, particularly the Apollonian Formation, exhibit a strong influence on borehole yields. The study identified areas with high transmissivity and hydraulic conductivity in the southern and eastern regions, suggesting good groundwater availability and suitability for sustainable water supply. Secondly, the research investigated the groundwater quality and observed that the majority of borehole samples fall within WHO (Guidelines for Drinking-water Quality, Environmental Health Criteria, Geneva, 2011, 2017. http://www.who.int) limit. However, some samples have pH levels below the standards, although the groundwater generally qualifies as freshwater. The study further explores hydrochemical facies and health risk assessment, highlighting the dominance of Ca–HCO₃ water type. Trace element analysis reveals minimal health risks from most elements, with chromium (Cr) as the primary contributor to chronic health risk. Overall, this study has provided a key insights into the Tano River Basin’s hydrogeology and associated health risks. The outcome of this research has contributed to the broader understanding of hydrogeological dynamics and the importance of managing groundwater resources sustainably in complex geological environments.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"325 - 353"},"PeriodicalIF":1.4,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139223938","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":"Weathering and accumulation of trace elements in the soils of the Porali Plain, Balochistan: repercussions in agriculture","authors":"Maria Kaleem,&nbsp;Erum Bashir,&nbsp;Shahid Naseem,&nbsp;Tahir Rafique,&nbsp;Bushra Shahab","doi":"10.1007/s11631-023-00651-5","DOIUrl":"10.1007/s11631-023-00651-5","url":null,"abstract":"<div><p>This study is the first attempt to assess the nature of the soil, especially on the western side of the Porali Plain in Balochistan; a new emerging agriculture hub, using weathering and pollution indices supplemented by multivariate analysis based on geochemical data. The outcomes of this study are expected to help farmers in soil management and selecting suitable crops for the region. Twenty-five soil samples were collected, mainly from the arable land of the Porali Plain. After drying and coning-quartering, soil samples were analyzed for major and trace elements using the XRF technique; sieving and hydrometric methods were employed for granulometric analysis. Estimated data were analyzed using Excel, SPSS, and Surfer software to calculate various indices, correlation matrix, and spatial distribution. The granulometric analysis showed that 76% of the samples belonged to loam types of soil, 12% to sand type, and 8% to silt type. Weathering indices: CIA, CIW, PIA, PWI, WIP, CIX, and ICV were calculated to infer the level of alteration. These indices reflect moderate to intense weathering; supported by K₂O/AI₂O₃, Rb/K₂O, Rb/Ti, and Rb/Sr ratios. Assessment of the geo-accumulation and Nemerow Pollution indices pinpoint relatively high concentrations of Pb, Ni, and Cr concentration in the soils. The correlation matrix and Principal Component Analysis show that the soil in this study area is mainly derived from the weathering of igneous rocks of Bela Ophiolite (Cretaceous age) and Jurassic sedimentary rocks of Mor Range having SEDEX/MVT type mineralization. Weathering may result in the undesirable accumulation of certain trace elements which adversely affects crops.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"214 - 234"},"PeriodicalIF":1.4,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139238729","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":"Geochemical fingerprints and hydrocarbon potential of Paleocene mudrocks in the Tano Basin, Ghana: insights from biomarkers and stable carbon isotopes","authors":"Kojo Amoako,&nbsp;Nancy Pearl Osei-Boakye,&nbsp;Ningning Zhong,&nbsp;N’Guessan Francois De Sales Konan,&nbsp;Gordon Foli,&nbsp;Prince Opoku Appau,&nbsp;Clifford Fenyi,&nbsp;Ebenezer Apesegah","doi":"10.1007/s11631-023-00652-4","DOIUrl":"10.1007/s11631-023-00652-4","url":null,"abstract":"<div><p>The Paleocene mudrocks in Ghana’s Tano Basin have received limited attention despite ongoing efforts to explore hydrocarbon resources. A thorough geochemical analysis is imperative to assess these mudrocks’ petroleum generation potential and formulate effective exploration strategies. In this study, a comprehensive geochemical analysis was carried out on ten Paleocene rock cuttings extracted from TP-1, a discovery well within the Tano Basin. Various analytical techniques, including total organic carbon (TOC) analysis, Rock–Eval pyrolysis, gas chromatography-mass spectrometry, and isotope ratio-mass spectrometry, were employed to elucidate their hydrocarbon potential and organic facies. The findings in this study were subsequently compared to existing geochemical data on Paleocene source rocks in the South Atlantic marginal basins. The results indicated that the Paleocene samples have TOC content ranging from 0.68 to 2.93 wt%. The prevalent kerogen types identified in these samples were Type II and Type III. Molecular and isotope data suggest that the organic matter found in the Paleocene mudrocks can be traced back to land plants and lower aquatic organisms. These mudrocks were deposited in a transitional environment with fluctuating water salinity, characterized by sub-oxic redox conditions. Maturity indices, both bulk and molecular, indicated a spectrum of maturity levels within the Paleocene mudrocks, spanning from immature to marginally mature, with increasing maturity observed with greater depth. In comparison, the organic composition and depositional environments of Paleocene source rocks in the Tano Basin closely resemble those found in the Niger Delta Basin, Douala, and Kribi-Campo Basins, the Kwanza Formation in Angola, and certain Brazilian marginal basins. However, it is worth noting that Paleocene source rocks in some of the basins, such as the Niger Delta and Brazilian marginal basins, exhibit relatively higher thermal maturity levels compared to those observed in the current Paleocene samples from the Tano Basin. In conclusion, the comprehensive geochemical analysis of Paleocene mudrocks within Ghana’s Tano Basin has unveiled their marginal hydrocarbon generation potential. The shared geochemical characteristics between the Paleocene mudrocks in the Tano Basin and those in the nearby South Atlantic marginal basins offer valuable insights into source rock quality, which is crucial for shaping future strategies in petroleum exploration in this region.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"255 - 279"},"PeriodicalIF":1.4,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139264057","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":"Early Paleozoic basement diorite of arc-magmatism from Kutch basin, Western India","authors":"Piyush Gupta,&nbsp;Sandeep Singh,&nbsp;Shakti Singh Rathore,&nbsp;Argha Narayan Sarkar","doi":"10.1007/s11631-023-00655-1","DOIUrl":"10.1007/s11631-023-00655-1","url":null,"abstract":"<div><p>In this study, we report for the first time an Early Palaeozoic basement diorite from the drilled well Nirona-A in the Banni Half-Graben of the Kutch basin, western India. The ⁴⁰Ar–³⁹Ar dates provided a plateau age of 441.84 ± 2.66 Ma and another pseudo plateau of 441.28 ± 5.82 to 388.08 ± 16.65 Ma for the basement diorite. These ages constrain the basement formation age to the Late Ordovician-Early Silurian period. The obtained basement ages are correlatable with the later part of Cambro-Ordovician alkaline magmatism that has been reported from the Huqf area in Central Oman, whereas their lithological and petrographic correlativity with basement diorites occurring in the Dinsi Body of Nagar Parkar igneous complex in Pakistan can also be envisaged. The geochemical studies characterized the diorite with enrichment of LILE (Rb, Ba, and K) and LREE (La, Ce, Nd), strong depletion of HFSE (Nb, Sr, P, and Ti), along with weakly negative Eu anomalies. The geochemical signatures indicate their petrogenetic affiliation with mantle-derived magmas, as well as their tectonic setting to be arc-related, having post-collisional continental-arc type affinity. The ~ 440 Ma basement of Kutch, therefore, appears to represent the later thermal event associated with the reworked Neoproterozoic subduction-related suite from Greater India’s northwest edge, which has implications for Gondwana assembly in the northwest Indian subcontinent.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 2","pages":"296 - 307"},"PeriodicalIF":1.4,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139275824","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":"Mineralogy and geochemistry of trachytic rocks from the Lichi Volcanics, Eastern Himalaya: insights into the Kerguelen mantle plume activity in the Eastern Himalayan Region","authors":"Pallabi Basumatary,&nbsp;Deepshikha Borah,&nbsp;Hiredya Chauhan,&nbsp;Tribujjal Prakash,&nbsp;Bibhuti Gogoi","doi":"10.1007/s11631-023-00650-6","DOIUrl":"10.1007/s11631-023-00650-6","url":null,"abstract":"<div><p>The Lichi volcanics are a suite of mafic-intermediate-felsic rocks and are considered coeval with the Abor volcanics (~132 Ma) of the Siang window in the Eastern Himalaya. Here, we present the first report of trachytic rocks from the Lichi volcanics, which are exposed in the Ranga valley, along the Kimin-Yazali road section in the Eastern Himalayan Region, Northeast India. The trachytes occur in close association with sandstones of the Gondwana Group of rocks and are characterised based on field, petrographical, and geochemical investigations. These fine-grained trachytes are composed of alkali feldspar, biotite, plagioclase, sodic-amphibole, apatite, illmenite, and titanite. The REE profiles of the evolved trachytic rocks (higher SiO₂ content) display fractionated trends. The fractionation of accessory mineral phases, like apatite and titanite, was possibly responsible for the strongly fractionated REE patterns of the evolved samples. The trachytic rocks demonstrate high apatite saturation temperatures of 988 ± 14 °C (1σ, n = 8). The Aluminium Saturation Index (&lt; 1.1) and binary discrimination diagrams of these peralkaline trachytes define their affinity with A-type granitoids. Elemental ratios like Y/Nb, Nb/U, and Ce/Pb signify that the Lichi trachytes are differentiated products of mantle-derived ocean island basalts. Trace elemental discrimination diagrams Th/Yb versus Nb/Yb, Y versus Nb, and Y + Nb versus Rb reflect a within-plate tectonic regime for the trachytes. From the results presented in this work, we infer that the development of rifting events during the breakup of eastern Gondwana due to the onset of Kerguelen plume activity further led to underplating of basic magma in lower crustal levels. These parental basaltic magmas underwent fractionation processes forming differentiated trachyandesites and trachytes. Taking into consideration the similarities recorded between the Lichi volcanics and Abor volcanics, this study supports the idea that Kerguelen plume activities resulted in the emplacement of these volcanics in the Eastern Himalayas.</p></div>","PeriodicalId":7151,"journal":{"name":"Acta Geochimica","volume":"43 1","pages":"180 - 197"},"PeriodicalIF":1.4,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135345452","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}