Journal of Asian Earth Sciences最新文献

{"title":"Apatite-bearing mantle xenoliths in Early Cretaceous basalts: Implications for geochemical modifications and carbon cycling in eastern North China Craton","authors":"Nongxin Yuan ,&nbsp;Cheng Xu ,&nbsp;Zhuoqi Li","doi":"10.1016/j.jseaes.2025.106596","DOIUrl":"10.1016/j.jseaes.2025.106596","url":null,"abstract":"<div><div>The eastern North China Craton (NCC) has undergone multistage lithospheric modifications through the recycling of subducted crustal materials. However, the mechanisms underlying the formation of carbon-rich domains in the subcontinental lithospheric mantle during the Late Mesozoic evolution remain poorly understood. Here, we report the petrological and in-situ geochemical characteristics of apatite-bearing mantle xenoliths from the Early Cretaceous Fangcheng basalts. The presence of near-equilibrium fluorapatites with olivines and clinopyroxenes along with a high proportion of clinopyroxenes and abundant CO₂ fluid inclusions in the wehrlites and olivine clinopyroxenites indicates the occurrence of carbonatite metasomatism. The geochemical compositions of the apatites show relatively high abundances of F (∼2.78 wt%) and Sr (∼3842 ppm), low Sr/Y (&lt;52) and high (La/Yb)_N (∼215) ratios, resembling apatite crystallizing from carbonatite magmas. Clinopyroxenes exhibit low Al and Ti concentrations and are characterized by low Ti/Eu ratio (517–1867) and high (La/Yb)_N (13–15) and Ca/Al ratios (7–9), consistent with geochemical trends associated with carbonatite metasomatism. Elevated Li concentration (&gt;3 ppm) and low V/Sc ratio (&lt;3) in olivines suggest the contribution of recycled crustal components to the peridotitic lithosphere. Additionally, highly enriched Sr-Nd isotopes reported in the Fangcheng basalts support the inference that Fangcheng wehrlites were metasomatized by carbonatite magmas derived from subducted carbonated pelites before being incorporated into the Early Cretaceous basaltic magmas. This metasomatic process serves as a crucial mechanism for lithospheric modifications and plays a key role in regional carbon cycling in the southeastern NCC, encompassing the subduction of carbonate-bearing continental crusts and subsequent devolatilization through mantle-derived volcanism.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"288 ","pages":"Article 106596"},"PeriodicalIF":2.7,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143808369","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 signatures and chemostratigraphic framework for the Early-Middle Permian sedimentary successions of Alborz, Iran","authors":"Forough Abasaghi,&nbsp;Armin Omidpour","doi":"10.1016/j.jseaes.2025.106607","DOIUrl":"10.1016/j.jseaes.2025.106607","url":null,"abstract":"<div><div>This research analyzes how the prevailing physicochemical conditions during the deposition of the carbonate intervals of the Ruteh Formation (Early-Middle Permian), in the Alborz, Iran, led to changes in water-column redox conditions. The significance of this study lies in providing unique insights into the oxic-anoxic variations in the Tethys Ocean during the detachment of the western Cimmerian microcontinent from Gondwana. The onset of interglacial periods and the opening of the Neo-Tethys in the Artinskian stage led to rising temperatures, oxic conditions, and a decrease in the enrichment factor and carbon isotope values. In contrast, the Kungurian oceans were suboxic to anoxic, as evidenced by positive carbon isotope values, high enrichment factor, positive Eu and Ce anomalies, and increased primary productivity. These geochemical changes are attributed to volcanic activities in the Early Kungurian, followed by the transgression of seawater during the opening of the Neo-Tethys and the movement of the Cimmerian microcontinent in the Late Kungurian. These factors played a crucial role in the development of oxygen-deficient basins and the upwelling processes. During the Roadian stage, oxic conditions once again dominated in the basin. The increase in temperature, coupled with the Cimmerian microcontinent’s movement towards equatorial latitudes, may have been a significant factor contributing to the decrease in carbon isotopic values, enrichment factor, and productivity proxies. The results obtained extend beyond previous studies, demonstrating that the deposition of the Ruteh Formation was closely linked to global events.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"288 ","pages":"Article 106607"},"PeriodicalIF":2.7,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799258","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":"Petrogenesis of early carboniferous and early Permian mafic intrusions in the Nanpanjiang Basin, SW China: Implications for northward subduction of the East Paleo-Tethys Ocean and back-arc basin formation","authors":"Xin Zhu ,&nbsp;Xiao-Ping Xia ,&nbsp;Jian Xu ,&nbsp;Qing Yang ,&nbsp;Zexian Cui ,&nbsp;M.P. Manu Prasanth","doi":"10.1016/j.jseaes.2025.106597","DOIUrl":"10.1016/j.jseaes.2025.106597","url":null,"abstract":"<div><div>The Nanpanjiang Basin (NPJB) is situated along the margins of the South China block (SCB) and the Indochina block (ICB). Its position is significant for evaluating the amalgamation histories of the two blocks, which shaped present-day Southeast Asia. However, the geological community has yet to reach a consensus on the formation and evolutionary history of the NPJB. Two competing models, which include the back-arc and foreland basins, have been proposed so far. This work employs apatite U-Pb dating and oxygen isotopes, whole-rock element and Sr-Nd isotope analyses on the Funing-Napo mafic intrusions (FNMI) in the Chinese Guangxi to evaluate the magmatic and tectonic aspects of the NPJB. The studied mafic intrusions are divisible into two groups based on their apatite ages: the Early Carboniferous (349–347 Ma, Group 1) and the Early Permian (295–284 Ma, Group 2). Group 1 samples display low SiO₂ (46.5–51.1 wt%) and high MgO (6.01–9.47 wt%). Group 2 samples show lower SiO₂ (44.5–49.2 wt%) and more variable MgO (3.39–13.7 wt%). Geochemical modeling based on the trace elements and isotopic compositions demonstrates that the FNMI were derived from an asthenosphere mantle source with OIB-like geochemical characteristics, metasomatized by melts originating from subducted sediments. The northward subduction of the East Paleo-Tethys Ocean (EPTO) beneath the SCB likely caused the onset of a back-arc extensional tectonic regime since the Early Carboniferous. The NPJB developed as a back-arc basin and facilitated a series of mafic magmatism in the Funing-Napo and surrounding areas during the Early Carboniferous and Early Permian.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"287 ","pages":"Article 106597"},"PeriodicalIF":2.7,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785970","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":"Tectonic uplift since the late Mesozoic and early geomorphological development of the north Qilian Shan on the NE Tibet Plateau: Insights from low–temperature thermochronology","authors":"Zheng Wenjun ,&nbsp;Wei Shiqi ,&nbsp;Jia Jiabao ,&nbsp;Wang Weitao ,&nbsp;Sun Xin ,&nbsp;Liu Bingxu","doi":"10.1016/j.jseaes.2025.106571","DOIUrl":"10.1016/j.jseaes.2025.106571","url":null,"abstract":"<div><div>The uplift history of the Qilian Shan and the formation time of modern landforms are key factors in establishing a northward expansion model of the Tibetan Plateau, although previous studies have obtained comprehensive results and an understanding of the areas at both ends of the Qilian Shan. The Gaizhangdaban Shan area, located in the mid–eastern section of the northern Qilian Shan, is characterized by the interplay of granite and Cambrian metamorphic strata, which collectively contribute to the pronounced topographical features in the central part of the Qilian Shan–Hexi Corridor. We employed apatite (U–Th)/He and zircon (U–Th)/He thermochronology, revealing a range of dates predominantly spanning from 300 Ma to 75 Ma. The cooling path model derived from our thermochronological data elucidates two distinct cooling events, dated at ∼78 Ma and ∼15 Ma respectively. Through a comparative analysis of the thermal history across the Qilian Shan range, we proposed that a progressive uplift extending from southern to northern regions commenced in the Late Cretaceous and occurred almost concurrently during the Miocene. We hypothesized that the Late Cretaceous cooling event was influenced primarily by the far–field effects of the collision between the Lhasa and Qiangtang blocks. The subsequent rapid Miocene uplift event is attributed to the closure of the Neo–Tethys Ocean and the consequent outward expansion of the Tibetan Plateau.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"287 ","pages":"Article 106571"},"PeriodicalIF":2.7,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143759799","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":"Orogenic segmentation across central and eastern Himalaya: Insights from source parameters derived from local earthquakes","authors":"Mita Uthaman,&nbsp;Chandrani Singh,&nbsp;Arun Singh,&nbsp;Abhisek Dutta","doi":"10.1016/j.jseaes.2025.106567","DOIUrl":"10.1016/j.jseaes.2025.106567","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Orogenic segmentation across the arcuate Himalayan belt complicates deformational trends beyond central Nepal. Here, we attempt to discern the implications of spatially varying deformation on seismic hazard potential in eastern Nepal, Sikkim and Bhutan Himalayas. A comprehensive catalogue of 2,018 local earthquakes recorded during past deployments is utilized to estimate source parameters from P and S wave spectra. Results indicate stress drop (Δσ) and moment magnitude exhibit scaled dependence with linearly increasing relation. Scaling traced between seismic moment and corner frequency (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; &lt;span&gt;&lt;math&gt;&lt;mo&gt;∝&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;&lt;sup&gt;protect relax special {t4ht=−}3&lt;/sup&gt;) indicates no breakdown of earthquake scaling law for small earthquakes, thus holding potential to be scaled for modelling large earthquakes in the region. Empirical relationships established (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.55&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;+1.43, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.68&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;)-6.20; &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.61&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;+1.33, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.66&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;)-6.06; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.66&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;+1.37, &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;=0.66&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;g&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;)-5.94) can serve as input for seismic hazard assessment in eastern Nepal, Sikkim and Bhutan. Spatial variability of Δσ is reflective of high coupling along the Main Himalayan Thrust (MHT), high strain rate and lower seismic activity in eastern Nepal and Bhutan. Strike-slip faulting in Bhutan (along DCFZ and KFZ) releases higher Δσ (&lt;span&gt;&lt;math&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;7–15 MPa) as compared to thrusting in Nepal releasing lower Δσ (&lt;span&gt;&lt;math&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;2 MPa). Low coupling along","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"287 ","pages":"Article 106567"},"PeriodicalIF":2.7,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143739013","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":"Effect of extractable organic matter on nanopore structure and heterogeneity in Triassic Yanchang lacustrine shale of the Ordos basin, China","authors":"Ruiliang Guo ,&nbsp;Xiaowei Liang ,&nbsp;Xinping Zhou ,&nbsp;Zhiqiang Fan ,&nbsp;Jingzhou Zhao ,&nbsp;Yubin Bai ,&nbsp;Weitao Wu ,&nbsp;Lei Cao ,&nbsp;Peng Liu","doi":"10.1016/j.jseaes.2025.106577","DOIUrl":"10.1016/j.jseaes.2025.106577","url":null,"abstract":"<div><div>The low-pressure nitrogen adsorption and multifractal analysis of Triassic Yanchang Chang 7 shale samples, before and after solvent extraction, were conducted on the effect of extractable organic matter (EOM) on pore microstructure, porosity, and heterogeneity. Chang 7 Shale, primarily composed of type II₁-II₂ organic matter (OM) and argillaceous-siliceous lithofacies, is characterized by interparticle and intraparticle pores in inorganic minerals, with limited development of OM pores. After extraction, pore volume and specific surface area significantly increased from 2.91 cm³/1000 g to 4.43 cm³/1000 g and 0.61 m²/g to 1.91 m²/g, respectively. This increase is attributed to the reopening of minor pores (&lt;23 nm) previously occupied by saturated hydrocarbons, which enhanced the proportion of minor pores and reduced overall pore heterogeneity. Saturated hydrocarbons in EOM were mainly enriched in carbonate interparticle pores, while aromatic hydrocarbons were concentrated in pyrite intraparticle pores. Resins and asphaltenes were predominantly adsorbed onto OM and inorganic mineral surfaces. Clay and pyrite intraparticle pores were nearly completely filled with EOM, reducing heterogeneity, whereas detrital mineral interparticle pores, partially filled with EOM, increased heterogeneity. A linear correlation between EOM content and Rock-Eval S₁ suggests that sample crushing may lead to an underestimation of saturated hydrocarbon content in S₁. These findings provide critical insights into the pore structure evolution and shale oil enrichment mechanisms in Yanchang Shale.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"287 ","pages":"Article 106577"},"PeriodicalIF":2.7,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684272","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":"HT-UHT metamorphism in the Dabie orogenic belt: A petrological study of garnet-plagioclaseamphibolite","authors":"Jiankang Tang ,&nbsp;Yonghong Shi ,&nbsp;Nanfei Cheng ,&nbsp;Chunlei Peng ,&nbsp;Genshan Yang","doi":"10.1016/j.jseaes.2025.106564","DOIUrl":"10.1016/j.jseaes.2025.106564","url":null,"abstract":"<div><div>The Dabie orogenic belt is pivotal for exploring ultrahigh-pressure (UHP) metamorphism. However, the occurrence of ultrahigh-temperature (UHT) metamorphism and its association with UHP metamorphism within this belt remain poorly constrained. Therefore, we conducted a detailed petrological investigation of garnet-plagioclase amphibolite from the Northern Dabie metamorphic belt, revealing five distinct metamorphic stages (M1, M2, M3-a, M3-b, and M4) with corresponding <em>P-T</em> conditions of 0.99 GPa/774 ℃, 0.75 GPa/766 ℃, 0.65 GPa/970–996 ℃, 0.65 GPa/824–854 ℃, and 0.27 GPa/737 ℃, respectively. Notably, the M3-a stage is identified as UHT metamorphism, supported by rare earth elements-based thermometry and the presence of amphibole symplectites (Amp = Cpx + Opx + Pl ± melt). Zircon U-Pb dating has yielded three age groups: Zrn-I (inherited magmatic zircons, 668–263 Ma), and the Zrn-II and Zrn-III groups (231 ± 3 Ma and 207 ± 3 Ma), with the latter two corresponding to the M1 and M2 metamorphic events. Furthermore, the protolith age of the granitic mylonite in structural contact with the garnet-plagioclase amphibolite was dated to 122 ± 1 Ma, indicating that the M4 event is contemporaneous or slightly older. The constructed <em>P-T</em> path reflects a gradual uplift process within the crustal level in the study area, involving isothermal decompression, isobaric heating, isobaric cooling, and decompression cooling. The transition from M1 to M3-b suggests initial uplift followed by termination, mirroring post-Triassic exhumation of the Dabie orogen, while the transition from M3-b to M4 may relate to Cretaceous extension.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"286 ","pages":"Article 106564"},"PeriodicalIF":2.7,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746967","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":"Geochemistry and geochronology of late Carboniferous granites from eastern Russia: Implications for the evolution of the Heihe–Nenjiang suture zone","authors":"Andrey A. Sorokin ,&nbsp;Yury V. Smirnov ,&nbsp;Wenliang Xu ,&nbsp;Hao Yang ,&nbsp;Valentin B. Khubanov","doi":"10.1016/j.jseaes.2025.106578","DOIUrl":"10.1016/j.jseaes.2025.106578","url":null,"abstract":"<div><div>The Heihe–Nenjiang suture zone, which is one of the major sutures in the eastern Central Asian Orogenic Belt, occurs between the Xing’an and Songnen–Zhangguangcai Range massifs and extends from southern Mongolia via northeastern China into eastern Russia. The amalgamation history of these massifs is controversial, especially for that during the late Paleozoic. Here we report whole-rock geochemical and zircon U–Pb geochronological data for two granite intrusions in the northeastern Heihe–Nenjiang suture zone with the aim of constraining the emplacement timing and their tectonic setting. In addition, combined with our previously published data for the Russian part of this suture zone, we compare tectonic processes between the two regions. We identified two monzogranites dated at 313 ± 3 and 307 ± 3 Ma, and a hornblende–biotite granite dated at 306 ± 2 Ma. The <em>ca</em>. 313 Ma and <em>ca</em>. 307 Ma monzogranites contain annite and have geochemical affinity to A₂-type granites. The geochemistry of the <em>ca</em>. 306 Ma hornblende–biotite granite, and the presence of edenite, pargasite, and siderophyllite, indicate it is an I-type granite. These late Carboniferous A₂- and I-type granites in the Russian part of the Heihe–Nenjiang suture zone formed during a 313–295 Ma magmatic event, which include 306 ± 4 Ma monzogranites, 301 ± 4 Ma rhyolites, and 295 ± 4 Ma plagiogranites with an adakitic signature. These rocks are all related to the post-collisional extension setting after the amalgamation of the Xing’an and Songnen–Zhangguangcai Range massifs.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"286 ","pages":"Article 106578"},"PeriodicalIF":2.7,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706029","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":"Potential geomagnetic instability during the Last Deglaciation: High-resolution paleomagnetic evidence from the South China Sea","authors":"Shuang Wu ,&nbsp;Xiaoqiang Yang ,&nbsp;Jiabo Liu ,&nbsp;Qiangqiang Wang ,&nbsp;Yonggang Yan ,&nbsp;Shengtan Shang ,&nbsp;Yueqin Wu","doi":"10.1016/j.jseaes.2025.106570","DOIUrl":"10.1016/j.jseaes.2025.106570","url":null,"abstract":"<div><div>The Last Deglaciation has been marked by numerous reports of geomagnetic excursions, though controversies persist due to uncertainties in their timing and the inconclusiveness of supporting evidence. In this study, we present new paleomagnetic data from ultra-high sedimentation rate core (up to 834 cm/kyr) from the South China Sea, which may reflect geomagnetic instability during this period. Based on 12 AMS ¹⁴C dates, we identify multiple intervals of reversed inclination between 14.5 and 11.5 ka. Our detailed rock magnetic and sedimentological analyses, in conjunction with the presence of shallow inclination anomalies in nearby records, suggest that these deviations likely represent genuine geomagnetic signals linked to excursion events. The observed transient and discontinuous directional changes, along with the geographically concentrated nature of our dataset, lead us to hypothesize that the sedimentary low-pass filter effect and the regionally confined occurrence of excursions contribute to the enigmatic nature of these anomalies in previous studies. The rapid and frequent directional shifts observed highlight the severe instability of the geomagnetic field during this period, potentially driven by non-dipole components. Nevertheless, further investigations are essential to confirm the validity of these hypotheses and to deepen our understanding of geomagnetic instability during this period.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"286 ","pages":"Article 106570"},"PeriodicalIF":2.7,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706030","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":"The redox transformation in the Yangtze Sea across the Ordovician-Silurian transition: Evidence from zinc isotopes in organic-rich shales","authors":"Jixin Jia ,&nbsp;Xuebin Du ,&nbsp;Ke Zhao ,&nbsp;Yongchao Lu ,&nbsp;Zhanhong Liu","doi":"10.1016/j.jseaes.2025.106579","DOIUrl":"10.1016/j.jseaes.2025.106579","url":null,"abstract":"<div><div>Across the Ordovician-Silurian transition, the Yangtze Sea exhibited a complex redox pattern influenced by various environmental factors. Consequently, investigating this phenomenon is crucial for understanding the paleoenvironmental changes and their implications. Numerous and continuously evolving geochemical proxies provide insights into the redox conditions of paleo-oceans, among which the zinc isotope composition (δ⁶⁶Zn) in organic rich shales has been recently discovered as a potential alternative proxy for local marine redox conditions. In this study, the core JY143, drilled in the middle Yangtze shelf, was selected as the research subject. The variation in δ⁶⁶Zn values can be categorized into three distinct stages. The substantial influx of isotopically light Zn from igneous materials and its interaction with seawater may contribute to an overall lighter Zn isotope composition in seawater (δ⁶⁶Zn_sw). Under conditions characterized by high paleoproductivity and elevated organic burial rates, biological absorption of light Zn is primarily responsible for the low δ⁶⁶Zn values observed in organic-rich shales, indicating that organic-rich shales serve as an isotopically light Zn sink in the Yangtze Sea across the transition. Notably, the δ⁶⁶Zn_sw values observed during stage 1 are significantly lower than those recorded in stages 2 and 3, as well as below lithogenic source, possibly because during the early diagenetic stage, an excess of isotopically light Zn relative to ZnS in pore water was remobilized and subsequently released into deep seawater under oxidizing conditions. In summary, the transformation from an oxic environment to an anoxic (and even euxinic) environment resulted in a marked increase in δ⁶⁶Zn_sw values. This study presents new evidence from Zn isotopes regarding the oxic-anoxic (and even euxinic) transformation in the Yangtze Sea during the transition, while further underscoring the potential utility of δ⁶⁶Zn in organic-rich shales as a redox proxy for local paleo-ocean environments.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"286 ","pages":"Article 106579"},"PeriodicalIF":2.7,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143680929","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}