Journal of Asian Earth Sciences最新文献

{"title":"Origin of leucosomes in a Kyanite-Zone migmatite of the Higher Himalayan Crystallines, Bhagirathi Valley (NW Himalaya)","authors":"Aman Kushwaha ,&nbsp;Sandeep Singh ,&nbsp;Shashank Prabha-Mohan ,&nbsp;Ian S. Williams ,&nbsp;Benita Putlitz ,&nbsp;Lukas P. Baumgartner ,&nbsp;Jean-Luc Epard","doi":"10.1016/j.jseaes.2025.106814","DOIUrl":"10.1016/j.jseaes.2025.106814","url":null,"abstract":"<div><div>This study encompasses field observations, petrography, whole-rock geochemistry, zircon and monazite geochronology, and oxygen isotope analysis to delineate the conditions and timing of partial melting in the Higher Himalaya Crystallines (HHC) along Bhagirathi Valley. Two distinct leucocratic layers (L-1 and L-2) were identified and studied to elucidate their formation mechanisms. Field evidence and petrographic studies indicate that the L-1 layer represents Tourmaline-bearing leucogranite (TBL) veins that infiltrated along extensional shear bands, while L-2 represents in-situ leucosomes generated during the partial melting of metasedimentary rocks. The peak metamorphic conditions were estimated at ∼ 720–740 °C and 1.0 GPa, which suggests that L-2 melts originated by fluid-assisted melting, rather than by closed system dehydration melting. Phase equilibria modelling suggests that protolith bulk composition, particularly the Na/K and Al/Si ratios, plays a critical role in melt chemistry, with elevated Na/K ratios in the host-rock promoting trondhjemite melts while lower Na/K ratios produce granitic melts. Zircon and monazite geochronology document two metamorphic episodes: an event at ∼ 35 Ma, which possibly represents melt generation at greater depth, and a subsequent episode at ∼ 21 Ma representing emplacement due to extensional tectonics. In-situ oxygen isotope analysis of zircon overgrowth suggests that intrusion of L-1 was accompanied by assimilation of surrounding metapsammite, recorded by a progressive increase in δ¹⁸O values from 7.5 ‰ at ∼ 25 Ma to 8.7 ‰ at |∼ 23 Ma. The high δ¹⁸O value (8.7 ‰) recorded by L-2 bearing migmatite is consistent with an origin by partial melting of a metapsammite protolith.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"293 ","pages":"Article 106814"},"PeriodicalIF":2.4,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219798","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":"Metamorphism and anatexis of high-pressure mafic granulites in the Dulan unit, North Qaidam, Northwestern Tibet","authors":"Jing Guo ,&nbsp;Yunshuai Li ,&nbsp;Guisheng Zhou ,&nbsp;Jianxin Zhang","doi":"10.1016/j.jseaes.2025.106813","DOIUrl":"10.1016/j.jseaes.2025.106813","url":null,"abstract":"<div><div>Metamorphism and anatexis of high-pressure (HP) mafic granulites are effective for revealing partial melting and metamorphic process in continental collisional orogenic belts. HP mafic granulites and associated adakitic leucosomes have been recognized in Dulan area, North Qaidam, however, the metamorphic evolution and the linkage between the metamorphism and anatexis remain ambiguous. Based on the petrographic textures and mineral assemblages, three phases of metamorphic evolution are recognized for the HP mafic granulites: (1) the amphibolite-facies prograde metamorphism, represented by mineral inclusions of plagioclase + amphibole + chlorite + quartz in the large-grained garnet; (2) the HP granulite-facies peak metamorphism, represented by garnet + matrix mineral assemblage: garnet + clinopyroxene ± amphibolite + plagioclase + kyanite + zoisite + quartz + rutile; (3) the retrograde metamorphic stage, represented by the symplectite of the fine-grained clinopyroxene + plagioclase in the large clinopyroxene and garnet grains, and the following intergrowth of light-green amphibolite + plagioclase on garnet rims. Conventional geothermobarometries yield the P-T conditions of 565–605 °C and 9.4–10.8 kbar, 15.2–17.9 kbar and 830–925 °C, and 720–795 °C and 11.8–13.2 kbar for the amphibolite-facies prograde metamorphism, the HP granulite-facies peak metamorphism, and the retrograde metamorphic stage, respectively. The P-T pseudosection shows that the HP mafic granulite experienced a clockwise P-T path with the peak stage at 891–910 °C/17.2 kbar and a partial melting degree of 45–50 %, forming the adakitic melts/TTGs. Zircon U-Pb dating suggests that the HP mafic granulites experienced a magmatic event at 458 ± 5 Ma followed by a metamorphic and anatectic event at 445 ± 2 Ma. The HP mafic granulites are rich in light rare earth elements and large ion lithophile elements (e.g., Ba, Sr, Th, U) and poor in high field strength elements (e.g., Nb, Ta, Ti), showing arc-related geochemical affinities. These arc magmatic rocks were buried to depths exceeding 56 km and heated to ca. 900 °C during collisional orogeny, and experienced HP granulite-facies metamorphism and anatexis. Geochronological and geochemical data demonstrate that the leucosome within the HP mafic granulite in the Dulan area may have been generated by the partial melting of metagabbro under HP granulite-facies conditions in an arc root, which migrated and converged to form the coeval tonalite plutons, with HP mafic granulite and garnet pyroxenite representing the residue. These results will provide key insights into the geotectonic processes of metamorphism and anatexis of arc magmatic rocks within the upper plate of the subduction zone as well as their significance for orogenesis.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106813"},"PeriodicalIF":2.4,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266672","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":"In-Cd-Ga enrichment in sphalerite from the Gaocheng skarn Pb-Zn-Ag deposit, Yunkai Domain, South China","authors":"Mengxuan Chen ,&nbsp;Yi Zheng ,&nbsp;Qian Huang ,&nbsp;Pengpeng Yu ,&nbsp;Taiping Zhao ,&nbsp;Xi Chen","doi":"10.1016/j.jseaes.2025.106806","DOIUrl":"10.1016/j.jseaes.2025.106806","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Indium (In), Gallium (Ga), and Cadmium (Cd) are strategic critical metals with widespread applications in high-tech industries. The growing demand and global supply limitations have led to widespread attention on the genesis and exploration of deposits rich in In, Ga, and Cd. The Yunkai Domain (Cathaysia Block, South China) contains numerous Zn-Pb polymetallic deposits, but the potential of In, Ga, and Cd in these deposits has been insufficiently studied. To fill this gap, we selected the Gaocheng deposit, a representative skarn-type Zn-Pb-Ag deposit, to investigate the content, spatial distribution, and incorporation behavior of In, Ga, and Cd in sphalerite, which serves as their major mineral host. Field surveys and microscopic observations revealed that the Gaocheng is featured with a variety of skarn minerals such as diopside, epidote, and garnet. Three generations of sphalerite have been identified with distinct mineral assemblages and colors. Electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses revealed that each sphalerite has distinct compositions, in particular In, Ga, and Cd concentrations. In Sp1 (n = 56), In (mean = 414 ppm), Ga (mean = 177 ppm), and Cd (mean = 11517 ppm) are the most enriched. The concentrations in the subsequent two generations of sphalerite show a decreasing trend, with Sp2 (n = 52) having In (mean = 271 ppm), Ga (mean = 119 ppm), and Cd (mean = 6196 ppm), and Sp3 (n = 49) having In (mean = 48 ppm), Ga (mean = 73 ppm), and Cd (mean = 5732 ppm).&lt;/div&gt;&lt;div&gt;Binary diagrams indicate that the substitution mechanism of In into the sphalerite lattice is: Cu&lt;sup&gt;+&lt;/sup&gt; (or Ag&lt;sup&gt;+&lt;/sup&gt;) + In&lt;sup&gt;3+&lt;/sup&gt; ↔ 2Zn&lt;sup&gt;2+&lt;/sup&gt;, and Ga follows a similar mechanism: Cu&lt;sup&gt;+&lt;/sup&gt; (or Ag&lt;sup&gt;+&lt;/sup&gt;) + Ga&lt;sup&gt;3+&lt;/sup&gt; ↔ 2Zn&lt;sup&gt;2+&lt;/sup&gt;, while the substitution mechanism for Cd is: Cd&lt;sup&gt;2+&lt;/sup&gt; ↔ Zn&lt;sup&gt;2+&lt;/sup&gt;. It is noticeable that the effect of the indium window, the highly enriched In, correlating with the specific Cd concentrations (4000–8000 ppm, 10000–14000 ppm), is observed in the Gaocheng sphalerite. Then, we use the GGIMFis geothermometer to calculate the crystallization temperatures of three sphalerite generations that exhibit a clear decreasing trend from 331 °C (mean) for Sp1 through 320°C for Sp2, to 309 °C for Sp3. Based on temperature and thermodynamic calculations, the sulfur fugacity (fS&lt;sub&gt;2&lt;/sub&gt;) shows a gradual decreasing trend, with Sp1 (−8 to −5), Sp2 (−10 to −6), and Sp3 (−13 to −9). Meanwhile, the oxygen fugacity (fO&lt;sub&gt;2&lt;/sub&gt;) of Sp1 and Sp2 in the earlier stages ranges from −34 to −28.5, with pH values between 4.9 and 6.7, while in the later stages, the oxygen fugacity (fO&lt;sub&gt;2&lt;/sub&gt;) of Sp3 ranges from −36 to −31.5, with pH values between 4.6 and 6.6. Collectively, we conclude that high temperature, elevated sulfur fugacity, higher oxygen fugacity, and weakly acidic physicochemical conditions are favorable for the ","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"293 ","pages":"Article 106806"},"PeriodicalIF":2.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145219797","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":"Hydrogeochemical characteristics and the monitoring from 2020 to 2023 of hot spring waters in Tatun Volcanic Group, Taiwan","authors":"Ju-lien Pi ,&nbsp;Hsueh-Yu Lu ,&nbsp;Hsiao-Fen Lee ,&nbsp;Hung-Chun Chao ,&nbsp;Chen-Feng You ,&nbsp;Tsung-Ren Peng ,&nbsp;Raymond Patrick R. Maximo ,&nbsp;Chia-Tai Wu ,&nbsp;Ya-Wen Wu ,&nbsp;Chung Fang ,&nbsp;Cheng-Horng Lin","doi":"10.1016/j.jseaes.2025.106807","DOIUrl":"10.1016/j.jseaes.2025.106807","url":null,"abstract":"<div><div>The Tatun Volcanic Group (TVG) is considered potentially active as indicated by the chemistry of fumarole gases and seismological data. The presence of magma volatiles in thermal water serves as a key signal of volcanic activity, making their monitoring crucial. However, other factors such as water–rock interactions can markedly obscure the water chemistry. The hydrogeochemical understanding of each hot spring site is essential in clarifying the source of components in hot springs. Based on the knowledge, the changes sourced from magma volatiles can be identified and help efficient monitoring of volcanic activities. In this study, nine spatially distributed hot spring sites were observed and monitored for 3 years in TVG. The monitored items include pH and major ions SO₄^2-, Cl^-, concentrations of total B, Na, Mg, Ca, K, Si, Al, Fe, Sr, Ba, ΣRFE, along with their ratios (B/Cl^-, Cl^-/SO₄^2-). Additionally, strontium isotope ratios (⁸⁷Sr/⁸⁶Sr), hydrogen isotopes (δ²H), and oxygen isotopes (δ¹⁸O) were also measured, albeit at a lower frequency. Based on the field observation and the comprehensive geochemical observation, we fully discussed the hydrogeochemical characteristics of each hot spring site. Recommendations are provided along with a database of three years’ worth of monitoring results, offering valuable information for future monitoring efforts.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106807"},"PeriodicalIF":2.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158020","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":"Genesis and geological significance of pyrite in the First Member of the Cretaceous Qingshankou formation of the Songliao Basin, NE China","authors":"Yan Wu ,&nbsp;Min Wang ,&nbsp;Xuefeng Bai ,&nbsp;Ying Li ,&nbsp;Xin Wang ,&nbsp;Yu Yan ,&nbsp;Changqi Yu ,&nbsp;Ming Li","doi":"10.1016/j.jseaes.2025.106811","DOIUrl":"10.1016/j.jseaes.2025.106811","url":null,"abstract":"<div><div>Pyrite is an important component for reconstructing the biogeochemical conditions and sedimentary environments of the earth’s surface in the past. The study on pyrite of Cretaceous Qingshankou Formation in the Songliao Basin not only helps elucidate the depositional processes of high-quality source rocks in the area, but is also important for reconstructing the Cretaceous paleoenvironment. Pyrite in the Qingshankou Formation includes euhedral pyrite, anhedral pyrite, fine-grained pyrite aggregates, pyrite framboids and polyframboids. The euhedral pyrite can be further divided into authigenic and secondary pyrite. Authigenic euhedral pyrite is directly precipitated from solution, while secondary euhedral pyrite is formed by recrystallization of pyrite framboids. The secondary pyrite can be further divided into compaction type and cementation type, indicating that the transformation of pyrite framboids into secondary euhedral pyrite is controlled by compaction and cementation, respectively. Anhedral pyrite is usually precipitated on the surface of iron-rich clay minerals (e.g., chlorite), or by metasomatism of other minerals, biological skeletons, and microorganisms. Framboidal pyrite is formed from greigite, and the amount, number of microcrystalline layers and particle size are related to the flow intensity of the water. This study provides a new understanding of the genetic mechanism of different types of pyrite.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106811"},"PeriodicalIF":2.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118282","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":"Geochemical constraints on the petrogenesis of Cenozoic adakitic porphyries in West Papua, Indonesia: implications for the metallogeny of the Grasberg Cu-Au deposit and associated tectonic evolution","authors":"Xiaoyong Yang ,&nbsp;Huasheng Qi ,&nbsp;Jianghong Deng ,&nbsp;Zhengwei Zhang","doi":"10.1016/j.jseaes.2025.106809","DOIUrl":"10.1016/j.jseaes.2025.106809","url":null,"abstract":"<div><div>The Cenozoic porphyries in the Grasberg area host a supergiant Cu–Au porphyry deposit in West Papua, Indonesia. These rocks display adakite-like geochemical features, including high Sr/Y and (La/Yb)N ratios, high Al₂O₃ and K₂O, low Y and Yb, and radiogenic Pb isotopes, distinguishing them from typical lower crustal melts. Integrated zircon U–Pb–Hf, whole-rock Sr–Nd–Pb isotopes, and trace element data indicate that three monzonite porphyries crystallized at 3.06 ± 0.19 Ma, 2.93 ± 0.16 Ma, and 2.86 ± 0.17 Ma. They show negative whole-rock εNd(t) (–9.8 to –8.5) and zircon εHf(t) (–20 to –1), high Ce⁴⁺/Ce³⁺ ratios (11.4–9056.7), and elevated oxygen fugacity, consistent with formation from oxidized, metal-fertile magmas.We propose that Grasberg porphyries formed by partial melting of an enriched, metasomatized lithospheric mantle mixed with melts from ancient lower continental crust. Mantle-derived magmas supplied heat, initial Cu–Au, high water content, and elevated fO₂, while crustal melts imparted adakitic signatures. Regional tectonics involved collisional delamination of the Australian continental lithosphere (starting ∼6 Ma), upwelling of hot asthenosphere, and decompression of stretched lithospheric mantle, promoting partial melting and magma mixing. Subsequent strike-slip faulting created pathways for shallow emplacement of adakitic monzonites, generating Cu–Au mineralization.High Ce⁴⁺/Ce³⁺ ratios and δ³⁴S values of pyrite and chalcopyrite indicate a magmatic source and strongly oxidized conditions, explaining the exceptional metal enrichment. This study establishes a geodynamic framework for the formation of igneous intrusions and the supergiant Grasberg Cu–Au deposit in a post-collisional, thin back-arc setting.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106809"},"PeriodicalIF":2.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158017","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":"Controls on Mn carbonate precipitation in the formation of Cryogenian Datangpo manganese deposits, southeastern Chongqing, South China","authors":"Zhiwei Liao ,&nbsp;Zhijie Xu ,&nbsp;Yi Zhang ,&nbsp;Xiaomeng Wang ,&nbsp;Hong Wu ,&nbsp;Xuanchun Liu ,&nbsp;Qin Huang ,&nbsp;Ye Wan","doi":"10.1016/j.jseaes.2025.106810","DOIUrl":"10.1016/j.jseaes.2025.106810","url":null,"abstract":"<div><div>The Cryogenian Datangpo Formation (ca. 663–654 Ma) in South China hosts globally significant sedimentary Mn deposits whose genetic mechanisms remain debated. To clarify their formation processes, the present study conducted integrated petrographic, mineralogical, and geochemical analyses of a new drill core from the Xiaochayuan subbasin (Nanhua Basin), southeastern Chongqing. Geochemical evidence show that Mn was predominantly derived from hydrothermal activity associated with extensional tectonics in the Nanhua Rift Basin during the breakup of the Rodinia Supercontinent. Variations in the Chemical Index of Alteration (CIA), together with regional correlations, indicate that Mn accumulation occurred under fluctuating cold and warm climatic conditions following the Sturtian glaciation. Enrichment of redox-sensitive elements and consistently low Mo/TOC ratios demonstrate Mn carbonate-bearing strata were deposited in a highly restricted, anoxic-euxinic environment. Positive Ce anomalies coupled with distinctly negative δ¹³C_carb values in the Mn carbonate rocks, provide compelling evidence for Mn oxide reduction mediated by organic matter degradation. The negative correlation between Mn content and δ¹³C_carb further supports that anaerobic oxidation processes generated HCO-3 supersaturation in porewaters. Microtextural analyses reveal that authigenic minerals with abundant nucleation sites, such as dolomite, pyrite and quartz, acted as catalytic substrates that facilitated Mn carbonate precipitation through heterogeneous nucleation. Collectively, these results establish a genetic framework in which organic matter accumulation, post-glacial climatic oscillations, hydrothermal influx, oceanic anoxia, and intensified continental weathering synergistically controlled the formation of these black shale-hosted Mn deposits.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106810"},"PeriodicalIF":2.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158022","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":"A Mid-Late Permian transition from oceanic subduction to continental collision in the northern margin of the North China Craton (NE China)","authors":"Xiaoxue Hou ,&nbsp;Qingxiang Du ,&nbsp;Yunfei Chang ,&nbsp;Jinrui Han ,&nbsp;Zuozhen Han ,&nbsp;Xiaoli Shen ,&nbsp;Huachun Gan","doi":"10.1016/j.jseaes.2025.106805","DOIUrl":"10.1016/j.jseaes.2025.106805","url":null,"abstract":"<div><div>The tectonic evolution of the northern margin of the North China Craton (NCC) remains controversial. In this study, we present zircon U-Pb ages, geochemistry, and Sr-Nd isotope data of andesites and dacites, and detrital zircon ages of siltstones from the Woguadi Formation in central Jilin Province, Northeast China. Dating of volcanic rocks from the Woguadi Formation yielded weighted mean ages ranging from 271 Ma to 256 Ma. The andesites are characterized by high Sr (635–746 ppm) and low Y (14.5–15.9 ppm) and Yb (1.41–1.51 ppm) contents, exhibiting geochemical affinities to adakites. Melts generated from partial melting of subducted oceanic crust interacted with peridotite during their ascent through the mantle wedge, most likely forming these andesites. The dacites show relatively low Sr (123–273 ppm) and high Y (14.7–29.4 ppm) and Yb (1.57–3.09 ppm) contents, displaying geochemical affinities to arc. These dacites formed from partial melting of crust metasomatized by fluids, sedimentary melts and mantle components, as supported by isotopic compositions (initial ⁸⁷Sr/⁸⁶Sr ratios of 0.7029–0.7044 and ε_Nd(t) values of 2.22–3.02). The volcanic rocks formed in an active continental margin related to southward subduction of the Paleo-Asian Ocean (PAO) during the Mid-Late Permian. Detrital zircons from the siltstones were mainly sourced from the NCC. The crustal thickness estimated by whole-rock trace elements and detrital zircon Eu/Eu* ratios suggests that the subduction initiation of the PAO occurred at ca. 330 Ma and the NCC and neighboring arcs began to collide at ca. 270 Ma.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106805"},"PeriodicalIF":2.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096044","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":"Magmatic-hydrothermal evolution of the Late Permian-Early Triassic Southeast Asian metallogenic system: Insights from the Chatree epithermal gold deposit, Thailand","authors":"Ladda Tangwattananukul ,&nbsp;Dussadee Rattanaphra ,&nbsp;Sasikarn Nuchdang ,&nbsp;Wilasinee Kingkam ,&nbsp;Kazunori Abe ,&nbsp;Punya Charusiri","doi":"10.1016/j.jseaes.2025.106804","DOIUrl":"10.1016/j.jseaes.2025.106804","url":null,"abstract":"<div><div>The Loei mineral belt is the significant for the Cu-Au-Fe province in magmatic arc-related terranes in mainland Southeast Asia, hosting epithermal Au and porphyry Cu-Au deposits. However, the relationship between magmatic activity and low-sulfidation epithermal mineralization remains unclear. Geochronological and stable isotope studies suggest that hydrothermal fluids played a dominant role in ore formation. This study focuses on petrography, geochemistry, geochronology and strontium isotopes to investigate the linkages between magmatic and gold mineralization. The deposit is hosted by Carboniferous to Triassic volcanic and sedimentary sequences, mainly in andesitic and rhyolitic breccias; andesitic volcanic rocks dominate the lower succession, yielding U-Pb zircon ages of 262–250 Ma while andesitic and basaltic dikes yield 244–238 Ma. Adularia ⁴⁰Ar/³⁹Ar dating constrains mineralization to 262–244 Ma, coinciding with the Late Permian to Early Triassic age. The geochronological analysis suggests at least two episodes of magmatism occurred: Late Permian (262–250 Ma), and Early Triassic (250–238 Ma). Insight into intense gold veins with the highest Sr isotope ratios (0.708765–0.717607) indicates that hydrothermal fluid interactions with the underlying sedimentary basement affected the ore fluid.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106804"},"PeriodicalIF":2.4,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096043","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":"Foraminiferal assemblages and microfacies analysis of Triassic − Jurassic boundary successions in Bitlis Massif Carbonates, eastern Türkiye: Insights into depositional environments and paleoenvironmental changes","authors":"Ayşe Atakul-Özdemir,&nbsp;Azat Narin","doi":"10.1016/j.jseaes.2025.106808","DOIUrl":"10.1016/j.jseaes.2025.106808","url":null,"abstract":"<div><div>Triassic-Jurassic boundary carbonate deposits of the Bitlis Massif (Çakmakkaya village, Elazığ, Türkiye) are considered to delineate paleoenvironmental changes, extinction events, and post-extinction recovery patterns through a combined approach of foraminiferal biostratigraphy and microfacies analysis. The studied sequences representing the most complete records of this boundary in eastern Türkiye are mainly dominated by peritidal carbonates. A high-resolution biostratigraphic investigation has defined four main biozones: (1) <em>Aulotortus</em> ex gr. <em>sinuosus</em> Assemblage Zone (Norian), (2) <em>Triasina hantkeni</em> Range Zone (Norian-Rhaetian), (3) <em>Thaumatoporella</em> sp. Zone (Hettangian), and (4) <em>Everticyclammina</em> sp. Zone (Sinemurian). The Late Triassic interval of the successions is generally characterized by involutinid forms, which abruptly disappear at the Triassic-Jurassic boundary. Following this extinction, the Early Jurassic is generally depicted by fossil-poor levels dominated by <em>Thaumatoporella</em> algae and by the appearance of siphovalvulinids and everticyclammins. The extinction of <em>Triasina hantkeni</em> and the disappearance of particular benthic foraminifers depict the Triassic-Jurassic boundary within the studied carbonate sequences, consistent with other Tethyan carbonate successions. Detailed microfacies analyses have revealed distinct microfacies types, suggesting a depositional model encompassing a transition from low-energy lagoonal environments to high-energy shoal settings and open marine conditions. The biotic events and microfacies characteristics underscore the global impact of this boundary event on the shallow marine carbonate platforms.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"294 ","pages":"Article 106808"},"PeriodicalIF":2.4,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096041","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}