Chemie Der Erde-Geochemistry最新文献

{"title":"Sideritization and silification of unconformity-related hydrothermal baryte veins near Grünau, south Namibia","authors":"Benjamin F. Walter ,&nbsp;Manuel Scharrer ,&nbsp;R. Johannes Giebel ,&nbsp;Aratz Beranoaguirre ,&nbsp;Jorge C.L. Arthuzzi ,&nbsp;Lorenz Kemmler ,&nbsp;Andreja Ladisic ,&nbsp;Saskia Dück ,&nbsp;Michael Marks ,&nbsp;Gregor Markl","doi":"10.1016/j.chemer.2024.126244","DOIUrl":"10.1016/j.chemer.2024.126244","url":null,"abstract":"<div><div>The development of economic mineralization within unconformity related hydrothermal vein type deposits is a topic of basic (but also economic) significance. In particular late-stage processes like pseudo- or perimorphic replacements can significantly influence the mineralogy and hence processability of ore deposits. This study aims to shed light on such late stage processes leading to the mineralogical modification of primary hydrothermal veins by pseudomorphous and perimorphous replacements of quartz after hydrothermal gangue minerals like carbonates, baryte and fluorite; whereas the genesis of pseudomorphic replacements of baryte by siderite and a contemporaneous perimorphic overgrowth of quartz has not been studied in detail so far. To study this process, hydrothermal veins of the south Namibian hydrothermal vein type district, which are related to the breakup of Pangea are chosen as natural laboratories.</div><div>Fluid inclusion data together with a detailed petrography of the paragenetic sequence and fluid inclusion assemblages reveal a temperature drop from early quartz I at ∼170 °C down to ∼80 °C in quartz III at almost constant salinities of 23.1 to 24.5 wt% (NaCl+CaCl₂). The chemistry of the observed fluid inclusion assemblages is in accordance with previous microthermometry studies carried out in the same hydrothermal vein type district indicating an identical provenance of the fluids recognized in the other deposits (e.g., Aukam and Garub). Hence it is likely that a high salinity basement brine of cryogenic origin has been mixed with a Nama Group limestone derived fluid to form the primary mineralization. Mixing of two chemically-contrasted fluids is also depicted by the trace elements studied in the youngest quartz generation whereas the application of the TitaniQ thermometer provide evidence for a temperature of about 320 °C in the deep-seated reservoir which became afterwards mixed with Nama Group limestone derived fluids. Thermodynamic modelling based on the gathered fluid data and data from analogue studies, provide evidence that siderite pseudomorphs after baryte form under reducing conditions, under which sulfate is reduced and the dissolution of baryte promotes siderite and pyrite precipitation. Hence, the present study contributes to the still weakly developed understanding how post-precipitation processes influences the mineralogy of hydrothermal veins.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126244"},"PeriodicalIF":2.6,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149983","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":"The Penjween gabbro, northeastern Iraq, revealing a forearc hyperextension regime with a slow spreading ridge center in the Late Cretaceous","authors":"Hossein Azizi ,&nbsp;Irfan Yara ,&nbsp;Sarmad Asi Ali ,&nbsp;Yousif O. Mohammad ,&nbsp;Yoshihiro Asahara ,&nbsp;Masayo Minami ,&nbsp;Ki-Choel Shin ,&nbsp;Ryo Anma ,&nbsp;Scott A. Whattam","doi":"10.1016/j.chemer.2024.126241","DOIUrl":"10.1016/j.chemer.2024.126241","url":null,"abstract":"<div><div>In the Zagros suture zone of western Iran, mafic and ultramafic rocks, along with deep marine sediments, are exposed and known as the Zagros ophiolites. Among these, the Penjween ophiolite in northeastern Iraq is notable and it is predominantly composed of gabbroic and mantle peridotite (tectonite), and also features minor felsic rocks like plagiogranites and mafic members such as pillow lavas and sheeted dikes. The Penjween gabbro which is the subject of this research were compressed between mantle peridotite to the east and Jurassic-Cretaceous cherts and Bistun limestone to the west. The chemical composition of the gabbroic rocks indicates low contents of alkaline elements, with higher FeO^t and MgO contents and low K contents and tholeiitic affinity. The basaltic and fine-grained gabbro have slightly higher alkaline element contents and LREE/HREE ratios than the gabbroic rocks, with slightly higher ⁸⁷Sr/⁸⁶Sr ratios (0.7038–0.7074) and lower ¹⁴³Nd/¹⁴⁴Nd ratios (0.51294–0.51301) than the gabbroic rocks with ⁸⁷Sr/⁸⁶Sr (0.7036–0.7054) ¹⁴³Nd/¹⁴⁴Nd (0.51281–0.51366) ratios. The basaltic rocks have a close affinity with the MORB composition, while the gabbroic rocks have Ce negative anomalies consistent with sources of hydrated depleted mantle melting. Therefore, given the 107 Ma age of the arc magmatic rocks in northwest Iran and the 98–93 Ma age of the plagiogranite in the Penjween area, the Penjween gabbros are 15–10 Ma younger than the magmatic activity in the northern Sanandaj-Sirjan zone (N-SaSZ) in western Iran. The Neotethys subduction probably began beneath the N-SaSZ at approximately 110 Ma, with nascent oceanic crust near the trench zone. Subsequently, the nascent plate spreading ridge slowly developed, resulting in the formation of the Penjween ophiolite in a supra-subduction system. The extensional regime in the forearc basin allowed for the exhumation of a large volume of mantle peridotite in the oceanic crust as a core complex. This process is known as forearc hyperextension, which has occurred in supra-subduction zones.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126241"},"PeriodicalIF":2.6,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561895","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":"Formation of carbonate-hosted Zn-Pb deposits in collision belts: An example from the Pirejman Zn-Pb + Ba deposit, SE Türkiye","authors":"Cem Kasapçı","doi":"10.1016/j.chemer.2024.126243","DOIUrl":"10.1016/j.chemer.2024.126243","url":null,"abstract":"<div><div>The Pirejman region Zn-Pb-Ba mineralizations are located north of Diyarbakır, south of the Bitlis-Zagros Suture Zone, within Upper Cretaceous and Eocene aged units. These mineralizations can be classified into two main groups based on the lithologies and ages of the rock hosting them. Each group is further subdivided into subgroups based on ore type and mineral paragenesis.</div><div>The first group developed within the Middle Jurassic-Lower Cretaceous limestone blocks embedded in the Upper Cretaceous aged Ophiolitic Melange. These mineralizations include the Pirejman Main -Zn-Pb deposit, the Sülfür Ocak deposit, and the Mezarlık Tepe deposits. The Pirejman deposit consists of sulfide and oxide‑carbonate Zn-Pb zones. The sulfide zones contain galena, sphalerite, and pyrite, while oxide‑carbonate zones primarily composed of smithsonite, hemimorphite, sericite, and iron oxides. The oxide‑carbonate ore formed as replacements in the adjacent rock and as karst fillings alongside the sulfide ore zone.</div><div>The second group of mineralizations developed within the carbonate rocks of Eocene-Oligocene-aged Midyat Group and is further divided into subgroups as barite and Pb-Zn-bearing barite mineralizations. These mineralizations generally occur in vein structures along N30–50°E and vertical fracture zones. They mainly consist of barite, with occasionally occurrences of galena and sphalerite.</div><div>The trace element contents of the mineralizations within the melange and Eocene-aged carbonates exhibit significant similarities. Moreover, the stable sulphur isotope values (δ³⁴SV-CDT) of barite and galena from both groups fall within a narrow range of 18–24 ‰ and resembling the isotopic values of MVT Pb-Zn deposits rather than those of SEDEX deposits in similar geological settings.</div><div>Field observations and analytical data suggest that the primary mineralization likely formed in the Middle Jurassic-Early Cretaceous interval within passive margin carbonates, probably as MVT Pb-Zn deposits. Subsequently, with the closure of the Neotethys Ocean, the initial MVT mineralizations were transferred into blocks during the Late Cretaceous. As the Neotethys Ocean completely closed during the Miocene, the region underwent uplift and deformation during the collision of the Arabian and Anatolian plates, resulting in thrusts and subsequently normal faulting in an extensional tectonic regime. Hydrothermal fluids circulating along these normal faults remobilized Pb, Zn, and Ba elements from the initial MVT ore bodies within the melange and formed vein-type Ba-Pb-Zn mineralizations along the normal faults. During this process, Pb-Zn mineralizations within the melange oxidized and transformed into supergene oxide‑carbonate Zn-Pb deposits.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126243"},"PeriodicalIF":2.6,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561705","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":"Petrogenesis and age of granitoids associated with the Dongshan Cu polymetallic deposit, East Kunlun Orogenic Belt, NW China: Implications for the Middle to Late Triassic tectonic setting and Cu polymetallic mineralization","authors":"Yi-Chen Chen ,&nbsp;Zheng-Jiang Ding ,&nbsp;Jun-Wei Bo ,&nbsp;Shi-Jiong Han ,&nbsp;Ting-Ting Li ,&nbsp;Pan Ji ,&nbsp;Rong-Qiang Guo","doi":"10.1016/j.chemer.2024.126240","DOIUrl":"10.1016/j.chemer.2024.126240","url":null,"abstract":"<div><div>The Dongshan Cu polymetallic skarn deposit is located in the eastern part of the East Kunlun Orogenic Belt (EKOB), NW China. The EKOB is an important Au-Cu-Fe polymetallic metallogenic belt. The mineralization is spatially-associated with granite porphyry and its contact with the Upper Triassic carbonates. In this paper, zircon U<img>Pb dating, whole-rock geochemistry, and zircon Hf isotope analysis were conducted to estimate the timing of intrusion emplacement, and identify magma sources and tectonic setting of the ore-related porphyry granite. Zircon U<img>Pb dating indicates that the emplacement ages are 239.6 ± 1.6 Ma and 235.6 ± 1.2 Ma, respectively. They belong to weakly peraluminous high-K calc-alkaline I-type granite, and exhibit significantly negative Eu anomalies (δEu = 0.31–0.39), depletions of high field strength elements and heavy rare earth elements (HREEs), and enrichment of large-ion lithophile elements (LILEs). Zircon Hf isotope compositions reveal that the ε_Hf(t) values range from −2.71 to 0.01, corresponding to T_DM2 of 1265–1437 Ma. These results suggest that the ore-related granite porphyry is originated from the partial melting of lower crust, mixed with the mantle-derived components. Furthermore, the ore-related granite porphyry in the Dongshan Cu polymetallic deposit shares characteristics of <em>syn</em>-collisional granites. Hence, we propose it was formed in a tectonic setting of continental marginal arc related to the northward subduction of the Paleo-Tethys Ocean.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126240"},"PeriodicalIF":2.6,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561900","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":"Mineralogical and geochemical characteristics of banded iron formations of the Dalli-Rajhara area, Central Bastar Craton: Implications for the origin and depositional environment","authors":"Samir Debnath ,&nbsp;Maitrayee Chakraborty ,&nbsp;Prasanta Kumar Mishra","doi":"10.1016/j.chemer.2024.126235","DOIUrl":"10.1016/j.chemer.2024.126235","url":null,"abstract":"<div><div>An integrated study involving field, mineralogy and whole-rock geochemistry is presented for a Mesoarchean (∼2.9–2.7 Ga) banded iron formations (BIF) from the Dalli-Rajhara area, central Bastar Craton, India. BIF bands preserve alternate Fe-rich magnetite bands and Fe-poor bands comprising dominantly chert with minor Fe-oxide minerals. The mineral chemistry of magnetite phases reveal FeO and Fe₂O₃ contents of 29.16–30.67 wt% and 66.53–68 wt%, respectively, whereas Al₂O₃ (0–0.03 wt%) and TiO₂ (0–0.08 wt%) contents are observed to be typical of BIF. Bulk rock geochemical analyses of the BIF show an average value of 97.19 wt% SiO₂ + Fe₂O₃^T, low Al and Mg, which indicate chemical precipitation as the process of formation. The absence of Al-rich mineral phases and a poor correlation between Al₂O₃ and TiO₂ suggest insignificant contamination by terrigenous clastic materials. The Post Archean Australian Shale (PAAS) normalized REE pattern shows positive La, Gd and Y anomalies and a superchondritic Y/Ho ratio (avg. 43), indicating the preservation of seawater-like signatures. Al/(Al + Fe + Mn) vs. Fe/Ti, ΣREE vs. Cu + Co + Ni, Eu/Sm vs. Sm/Yb and Eu/Sm vs. Y/Ho ratio plots suggest the participation of hydrothermal fluids during deposition. From the Eu anomaly, we infer anoxic condition and intense hydrothermal activity in the basin during the deposition of BIF. This study reveals that the Dalli-Rajhara BIF shares strong similarities with Archean Algoma-type BIFs, regarding (a) stratigraphic linkages with amphibolites (meta-volcanics) and (b) a higher Eu anomaly (avg. 5.1). Based on the field observations and geochemical signatures, we suggest that the Dalli-Rajhara BIF was deposited in a submarine volcanic environment mixed with seawater similar to those of Archean Algoma-type BIFs.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126235"},"PeriodicalIF":2.6,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561818","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":"Petrogenesis of the Late Cretaceous intrusive series in the Strandja Massif, Kırklareli-Türkiye","authors":"Ezgi Ulusoy ,&nbsp;Yusuf Kağan Kadıoğlu","doi":"10.1016/j.chemer.2024.126221","DOIUrl":"10.1016/j.chemer.2024.126221","url":null,"abstract":"<div><div>The Strandja Massif is located in northwestern Türkiye and is intruded by the Late Cretaceous intrusives formed by the Apuseni-Banat-Timok-Srednogorie magmatic arc, which resulted from the closure of the Tethys Ocean. The Late Cretaceous Strandja Intrusives are generally divided into five subgroups: (I) granitoids (Demirköy Intrusion), (II) monzonites (Karacadağ Intrusion), (III) syenites (Dereköy Intrusion), (IV) diorite (Değirmentepe Intrusion), and (V) gabbro (İncesırt Intrusion). The felsic rocks consist of quartz, orthoclase, oligoclase-andesine (An_19-48Ab_50-78Or_1.1-2.1), Fe-biotite, Mg-hornblende, and augite in varying proportions. Geochemical and isotopic analyses indicate that their formation was influenced by fractional crystallization and crustal contamination resulting from crust-mantle interaction. The mafic rocks, which occur predominantly as diorite and gabbro intrusions are mainly composed of labradorite-bytownite (An_75-25Ab_71-24Or_4.5-0.5), Fe-biotite, tschermakite-pargasite, and augite (Wo_27-45En_36-46Fs_25-13), with the occasional presence of olivine or quartz in variable proportions. The Sr-Nd isotopic compositions of felsic rocks in the Strandja Intrusives show an enrichment trend, with granitoids having ⁸⁷Sr/⁸⁶Sr values from 0.705801 to 0.706319 and ¹⁴³Nd/¹⁴⁴Nd from 0.512506 to 0.512599, while syenites have ⁸⁷Sr/⁸⁶Sr values between 0.707632 and 0.708293 and ¹⁴³Nd/¹⁴⁴Nd between 0.512420 and 0.512558. The ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd values of the diorite and gabbro intrusions range from 0.704408 to 0.707518 and from 0.512486 to 0.512716, respectively. The geothermobarometric data from the Strandja Intrusives reveal a complex magmatic system with clinopyroxene crystallization occurring under variable high-pressure and high-temperature conditions indicative of deep lithospheric and arc-related magmatic processes. The U-Pb zircon ages obtained are 82.1 ± 1.4 Ma for granites, while for syenites, they are 79.03 ± 0.6 Ma. Meanwhile, the U-Pb zircon ages of mafic intrusions undergoing bimodal evolution vary from 85.6 ± 0.8 Ma to 81.80 ± 0.42 Ma. The variation in U-Pb age data from east to west in the felsic intrusive rocks suggests a general rejuvenation from granite-granodiorite to syenite. It confirms that the Strandja Intrusives formed due to the northwestward subduction of the Vardar Ocean due to the compression between Africa and Eurasia during the Late Cretaceous period.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126221"},"PeriodicalIF":2.6,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561703","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":"Geochronology and petrology of Late Cretaceous subduction-related volcanics from Elazığ, SE Türkiye: Insights into deciphering petrogenesis and magma generation processes","authors":"Mehmet Ali Ertürk","doi":"10.1016/j.chemer.2024.126234","DOIUrl":"10.1016/j.chemer.2024.126234","url":null,"abstract":"<div><div>Subduction-related magmatism, representing the arc setting active just before the collision of the Arabian and Anatolian plates, crops out in large areas in the Southeastern Anatolian Orogenic Belt (SAOB). This study provides new geochemical and geochronological data that may provide important evidence for a more comprehensive understanding of the Late Cretaceous magmatism and evolution processes in the region. The trace element behaviour of igneous rocks bears traces of an N-MORB-like mantle source. The values of ⁸⁷Sr/⁸⁶Sr_(i) range from 0.705250 to 0.706114, ¹⁴³Nd/¹⁴⁴Nd_(i) from 0.512834 to 0.512888, and Ɛ_Nd(t) from 5.9 to 7.0. Zircon U<img>Pb dating indicates that the crystallisation age of the volcanism is 83.93 ± 1.21 Ma. Energy-constrained assimilation-fractional crystallisation (EC–AFC) modelling confirms that the studied rocks are contaminated by the lower crust to a quite low degree, between ~0.1 and 0.4 %. The volcanics were produced from a spinel lherzolite source, with low-medium degree partial melting (~1–12 %). According to the mixing calculation modelling, slab-derived components were involved by approximately 1–4 wt% in magma generation. The estimated mantle melting temperature and pressure conditions from the composition of volcanic rocks were between 1322 and 1442 °C and 1.07–2.14 GPa, respectively. The geochronological and geochemical constraints suggest that the possible sources and evolution of the subduction-related volcanics (SRV) record tectonic processes in an intra-oceanic arc setting in response to northward subduction during the Late Cretaceous.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126234"},"PeriodicalIF":2.6,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561704","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":"Sedimentary response of the superposition of two major tectonic systems on the southern margin of the South China Block during the Late Triassic","authors":"Dazhi Xu ,&nbsp;Zhongjie Xu ,&nbsp;Rihui Cheng","doi":"10.1016/j.chemer.2024.126222","DOIUrl":"10.1016/j.chemer.2024.126222","url":null,"abstract":"<div><div>To confirm the potential provenance and the dynamic mechanism of basin evolution of the southern margin of the South China Block in the Late Triassic, we choose the Mashui Town section in Yangchun, western Guangdong as the study area. This article uses whole-rock geochemical analyses, sandstone detrital mode, detrital zircon ages, trace-element composition and basin provenance of the Late Triassic Xiaoping Formation to conclude that the southern margin of the South China Block was deposited in a complex tectonic setting during the Late Triassic. The detrital zircons of the Late Triassic Xiaoping Formation have major age groups of 1150–815 Ma, 550–340 Ma, and 300–220 Ma. We suggest that the detritus probably was recycled form the Proterozoic basement and derived from the Phanerozoic Wuyi Terrane, Yunkai Terrane, and Hainan Island area. The complex tectonic setting has both the characteristics of a peripheral foreland basin and an active continental margin, reflecting its superposition influence by the two major tectonic systems of the Paleo-Tethys Ocean and the Paleo-Pacific Ocean.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126222"},"PeriodicalIF":2.6,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561904","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":"Tectonics and climate controlled sedimentary provenance in the Teesta basin since mid-Holocene","authors":"Satyabrata Das ,&nbsp;Sunil Kumar Singh ,&nbsp;Santosh K. Rai ,&nbsp;Saurabh Singhal ,&nbsp;Waliur Rahaman ,&nbsp;Rakesh Kumar Rout ,&nbsp;Sajid Ali","doi":"10.1016/j.chemer.2024.126224","DOIUrl":"10.1016/j.chemer.2024.126224","url":null,"abstract":"<div><div>Erosion of the Himalaya Mountain and subsequent deposition of sediments in the flood plains, and distal fans are primarily regulated by tectonics, climates, lithology, and relief of the region. These eroded sediments preserve their chemical and isotopic compositions in their depositional archive, which can be used to trace the erosion processes and assess the relative role of controlling factors and their spatio-temporal variations. The present study has analysed the ⁸⁷Sr/⁸⁶Sr and Ԑ_Nd of in silicate phase of sediment recovered from a ~ 40 m long sedimentary core representing ~8 ky of sediment accumulation in the Teesta River mega fan. The lithostratigraphy of the core indicates rapid aggradational nature of the Teesta mega fan. The ⁸⁷Sr/⁸⁶Sr and Ԑ_Nd display large variability with depth, which ranges from 0.75700 to 0.89294 and − 15.1 to −25.0, respectively. The observed ⁸⁷Sr/⁸⁶Sr and Ԑ_Nd values in the core sediments have been interpreted in terms of differential sediment contribution from the Higher and the Lesser Himalayan lithology. The ⁸⁷Sr/⁸⁶Sr and Ԑ_Nd isotope profiles and estimated fractional sediment contributions identify the Lesser Himalaya as the major sediment contributor to the Teesta basin since the mid-Holocene, unlike the other Himalayan River basins, dominated by sediments from the Higher Himalaya after the Last Glacial Maximum. The rapid exhumation and erosion of the tectonically active Rangeet window with the focused precipitation and presence of rock types vulnerable to weathering in the Lesser Himalaya of the basin appear to be the major factors resulting in the sedimentary budget of the Teesta River basin over at least last 8 ky. Our assessment suggests that tectonic activity and climate have a competitive effect on the observed sedimentary budget, with an additional role of lithology. The study infers a major control of active tectonics, precipitation, and lithology on the sedimentary budget of the Himalayan River basins.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126224"},"PeriodicalIF":2.6,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561815","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":"Comparative mineralogical characterization of REEs ore samples from the Mushgai Khudag and Lugiin Gol deposits, Mongolia","authors":"Ni He ,&nbsp;Xiaoyu Meng ,&nbsp;Liang Hu ,&nbsp;Li Shen ,&nbsp;Sarangerel Davaasambuu ,&nbsp;Hongbo Zhao","doi":"10.1016/j.chemer.2024.126223","DOIUrl":"10.1016/j.chemer.2024.126223","url":null,"abstract":"<div><div>Mongolia, situated in the Central Asian orogenic belt, is characterized by geology that is highly conducive to the abundance of mineral resources, including significant rare earth elements (REEs) reserves. However, limited knowledge of the mineralogy of its deposits has hindered the development of efficient REEs extraction methods. This study presents a detailed investigation of the mineralogical characteristics of Mongolian ores and analyzes their compositions, mineral associations, liberation, and REEs concentrations via advanced analytical techniques, including the TESCAN Integrated Mineral Analyzer (TIMA). Additionally, the BCR sequential extraction method was employed to determine the binding and leaching properties of REEs. Our results revealed that the two ore samples were predominantly rich in light rare earth elements (LREEs), with REE-bearing minerals closely associated with gangue minerals such as calcite, albite, and quartz, leading to poor liberation. The extraction data indicated that &gt;85 % of the REEs in the Mushgai Khudag deposit were retained in the residual fraction, whereas in the Lugiin Gol deposit, the majority of the REEs were associated with the reducible fraction. These findings underscore the challenges associated with extracting REEs from Mongolian deposits, which demand stringent conditions for effective recovery. This research contributes valuable insights into the complex mineralogy of Mongolian REEs deposits, offering a foundation for future advancements in REE extraction technologies.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126223"},"PeriodicalIF":2.6,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561817","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}