Journal of Asian Earth Sciences最新文献

{"title":"The activity of the Khanaqin Fault, east of Iraq and west of Iran, as deduced from Neotectonic evidence and seismicity","authors":"Varoujan K. Sissakian ,&nbsp;Rami Ibrahim ,&nbsp;Sangar Ali Ahmed ,&nbsp;Samvel A. Mkhitaryan","doi":"10.1016/j.jseaes.2025.106653","DOIUrl":"10.1016/j.jseaes.2025.106653","url":null,"abstract":"<div><div>The Khanaqin Fault is an N-S extending thrust fault with a shallow dipping angle towards the northeast, with a length of about 125 km. Although the majority of the fault runs in the western side of Iran, it is still called the Khanaqin Fault referring to Khanaqin town in the eastern part of Iraq. In Iraq, the red clastic rocks of the Gercus Formation are thrusted over the carbonate rocks of the Avanah and Pila Spi formations. The Eocene carbonates are thrusted over Oligocene carbonate rocks, which in turn are thrusted over clastic rocks of the Injana Formation; forming a complex of faulted rocks along the border with Iran. The fault planes are not so clear when carbonate rocks are thrusted over carbonate rocks (the second case), whereas in the first and third cases, the fault planes are very clear with a lot of deformations, especially in claystone rocks. On 12 November 2017, an earthquake with a magnitude of 7.3 and a depth of 19 km hit the border area between Iraq and Iran. The epicenter of this earthquake is located 86 km southeast of Sulaymaniyah city and 81 km northeast of Khanaqin town. We have used satellite images and geological maps of different scales to recognize the extension and location of the fault. We also recognized many Neotectonic indications of the region’s tectonic activity. Moreover, the seismic activity recorded for more than a century aligns with the conclusions of this study.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106653"},"PeriodicalIF":2.7,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144106441","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 deformation-based seismic hazard model for the Makran region","authors":"A. Lotfi ,&nbsp;H. Zafarani ,&nbsp;H. Ghadimi ,&nbsp;A. Khodaverdian","doi":"10.1016/j.jseaes.2025.106664","DOIUrl":"10.1016/j.jseaes.2025.106664","url":null,"abstract":"<div><div>The most prevalent approach for evaluating earthquake hazard is the probabilistic seismic hazard analysis (PSHA), which commonly relies on earthquake catalogs. However, in subduction zones like Makran, southeast Iran where the return period of large-magnitude (Mw 7+) characteristics events is more than ∼1000–2000 years, the complementary data from deformation models are crucial to put more efficient constraints on the seismicity activity. An alternative method to address this issue, known as deformation-based PSHA involves estimating activity rates from deformation-based strain rates. Here, we estimate the earthquake occurrence rates for events with <em>M_w</em> 4+ using strain rates derived from a comprehensive deformation model of the Makran region, using complementary regional seismicity parameters, such as <span><math><mi>β</mi></math></span> and <span><math><msub><mi>m</mi><mi>max</mi></msub></math></span>. As a representative, we selected a limited number of points in each seismic province and compared them to their long-term activity rate estimations based on available catalogs. Our deformation-based hazard model estimates higher hazard levels than other catalog-based models, for a substantial portion of the study area.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"289 ","pages":"Article 106664"},"PeriodicalIF":2.7,"publicationDate":"2025-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089054","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 genetic link between magmatic evolution and indium mineralization in the Dulong Sn-polymetallic deposit, Southwest China: Constraints from the compositions of mica and apatite","authors":"Liyuan Wang ,&nbsp;Xinhe Deng ,&nbsp;Jing Xu ,&nbsp;Taiping Zhao ,&nbsp;Wenyuan Liu","doi":"10.1016/j.jseaes.2025.106666","DOIUrl":"10.1016/j.jseaes.2025.106666","url":null,"abstract":"<div><div>The Dulong deposit is a world-class Sn-polymetallic deposit with indium mineralization, which is associated with highly evolved Late Cretaceous S-type granites, indicating the magmatism is crucial for the indium enrichment. Through integrated in-situ geochemical analyses of mica and apatite across variably fractionated granites and country rocks, this study reveals a systematic evolution of redox conditions, halogen chemistry, and metal enrichment during magmatic differentiation. As magmatic evolution progresses, indium and tin contentratons in mica increase progressively, reaching peak vales in the late stage of evolution at Dulong deposit. Notably, indium concentration in muscovite is greater than that in biotite, when muscovite converts into phengite. Apatite and mica compositions indicate low oxygen fugacity (<em>f</em>O₂) magmatism. Fe-rich biotite in Sn-In-bearing granites contrasts with Mg-biotite in Sn-poor systems, with Fe³⁺/(Fe²⁺+Fe³⁺) ratios &lt; 0.2 confirming reduced fO₂ conditions conducive to indium melt incorporation. Apatite geochemistry reinforces this: low SO₃ (0.01–0.08 wt%), As depletion (14.54–42.10 ppm), and marked negative Eu anomalies (Eu/Eu* &lt;0.4). Multi-proxy evidence collectively confirms a reduced magmatic system. Integrated proxies confirm a reduced magmatic system where progressive redox reduction during differentiation fosters indium enrichment, enhancing metallogenic potential. Concurrently, apatite halogen signatures track magmatic evolution: sustained F enrichment with late Cl spikes aligns with mantle-derived inputs evidenced by mafic enclaves. Although Cl concentrations remain low in the early magmatic stages, their subsequent dramatic increase correlates temporally and genetically with marked enrichment of In and Sn during later evolutionary phases. The mixing of mantle-derived magmas may bring in Cl-rich fluids/melts and related ore-forming materials, which promotes indium mineralization. The concurrent enrichment of halogen elements, F and Cl, plays a crucial role in the extraordinary accumulation of indium.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"289 ","pages":"Article 106666"},"PeriodicalIF":2.7,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144107571","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":"Deciphering Sb–Au mineralization event in the Longshan deposit, South China: Linking sulfide geochemistry and hydrothermal alteration","authors":"Kui Jiang ,&nbsp;Wei Li ,&nbsp;Dayong Liu ,&nbsp;Guiqing Xie ,&nbsp;Lei Cai ,&nbsp;Degong Wang","doi":"10.1016/j.jseaes.2025.106659","DOIUrl":"10.1016/j.jseaes.2025.106659","url":null,"abstract":"<div><div>The Longshan is one slate-hosted Sb–Au deposit located in the Jiangnan orogenic belt, South China. It features two sets of mineralized quartz veins, striking in NE and NW directions, respectively. It remains unclear whether these veins are the products of one or two Au–Sb mineralizing event (s). In this study, geological investigation, TESCAN Integrated Mineral Analyzer (TIMA), coupled with high sensitivity laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) trace elements analyses of pyrite and arsenopyrite were performed to reveal the sulfides (pyrite and arsenopyrite) geochemistry, paragenesis and types of hydrothermal alteration. These results indicate that wallrock hydrothermal alteration is intensive for both vein sets, with the main alteration types being silicification, sericitization, sulfidation, and carbonatization. Detailed texture investigations show that there is an insignificant difference between these two sets of quartz veins, as zoning texture is well-developed for pyrite whereas arsenopyrite shows weak inhomogeneity. LA–ICP–MS trace elements concentrations also display similar ranges such as Au and Sb for both pyrite and arsenopyrite from both sets of veins. Complemented by the time gap between the ore-hosting structure (Late Triassic) and mineralization ages (Late Jurassic), we prefer to explain the formation of two sets quartz veins in the Longshan Sb–Au deposit as resulting from a single pulse of hydrothermal fluid infilling pre-existing structures, rather than from superimposed Sb–Au events. This interpretation explains the similarities in the nature of ore-forming fluids and processes.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106659"},"PeriodicalIF":2.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114933","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":"Examining trace elements of cassiterite as fingerprints for tectonic settings of tin deposits: An example from the SE Asian tin province","authors":"Zhi Zhang ,&nbsp;Jie-Hua Yang ,&nbsp;Jing-Hua Wu ,&nbsp;Wei Mao ,&nbsp;Qian Hu ,&nbsp;Yin-Peng Lu","doi":"10.1016/j.jseaes.2025.106660","DOIUrl":"10.1016/j.jseaes.2025.106660","url":null,"abstract":"<div><div>Southeast Asia is a major global tin province and consists of three metallogenic belts: the Eastern, Central, and Western belts, which formed in oceanic subduction, continental collision, and post-subduction extensional settings, respectively. This study applies machine learning (eXtreme Gradient Boosting and SHapley Additive exPlanations) to cassiterite trace element data from SE Asia to identify key fingerprint elements and/or element ratios that distinguish these settings. Significant differences in Ti/Hf, Zr/Hf, Sc/Hf, Ti/Fe, and W/U ratios were observed, aligning with machine learning results. Compiling geochemical data from ore-forming granites in the three belts indicates that the elemental composition of cassiterite is closely linked to the geochemical characteristics of the corresponding granites. In the Western belt, mantle degassing contributed to highly evolved, fluorine-rich granites, producing cassiterite with the lowest Ti/Hf, Zr/Hf, and Sc/Hf ratios. The Central belt granites, derived from a reduced crust in a collision setting, enriched fluids in divalent Fe, leading to cassiterite with the highest Ti/Fe ratio. The Eastern belt, associated with fewer W-bearing minerals, shows higher W/U ratios due to limited tungsten depletion in ore-forming fluids. Using these five fingerprints, linear discriminant functions distinguish the three belts with 87% accuracy. Our findings indicate that the volatile content, differentiation, and oxygen fugacity of magma vary with tectonic settings and significantly influence the trace element composition of cassiterite. Therefore, this evolutionary pattern, from tectonic settings to magma properties and ultimately to tin mineralization characteristics, suggests that cassiterite may serve as an effective indicator for determining the tectonic setting of tin deposits.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106660"},"PeriodicalIF":2.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144071379","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":"Ore-forming fluid for the formation of banded iron formation-hosted high-grade magnetite ores of the North China Craton: Constraints from pyrite trace elements and sulfur isotopes","authors":"Yi Wang ,&nbsp;Li-Xing Li ,&nbsp;Hou-Min Li ,&nbsp;Jian-Fei Fu ,&nbsp;Yang Dai ,&nbsp;Xiao-Hui Wang ,&nbsp;Xuan Wu","doi":"10.1016/j.jseaes.2025.106663","DOIUrl":"10.1016/j.jseaes.2025.106663","url":null,"abstract":"<div><div>Banded iron formation-hosted high-grade iron ore deposits are among the most important global sources of iron. Although less common than hematite ores, high-grade magnetite ores represent another significant type, occurring mainly in northern North China Craton. These ores are generally considered to have formed through the interaction of high-temperature hydrothermal fluids with ∼2.55 Ga BIF protore, yet the nature and origin of ore-forming fluids remain uncertain. Two types of high-grade magnetite deposits have been classified based on their size and alteration features: the Gongchangling type and Qidashan type. In situ trace-element and sulfur isotopic analyses were conducted on pyrite from BIFs, high-grade magnetite ores, and altered rocks surrounding high-grade orebodies. In high-grade magnetite deposits, sulfur isotopes may be influenced by multiple factors, making them less effective in constraining the source of ore-forming fluids, whereas trace element analysis of pyrite could provide more precise insights into fluid nature and source. The ore-forming fluids in both deposits exhibit characteristics of hydrothermal systems associated with deep-seated magmatic activity. In the Gongchangling deposit, the ore-forming fluids were primarily derived from magmatic activity at ∼1.85 Ga, with additional contributions from fluids leaching Paleoproterozoic Co-Ni-rich geological bodies. In contrast, the Qidashan deposit is dominated by As-Se-rich fluids originating from magmatic-hydrothermal activity around ∼2.5 Ga. We propose that deep-seated magmatic activity is fundamental for forming high-grade iron deposits, whereas the development of large-scale deposits, such as the Gongchangling deposit, requires multi-phase hydrothermal activity involving Co-Ni-rich ore-forming fluids.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"289 ","pages":"Article 106663"},"PeriodicalIF":2.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144107620","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 rodingite in the Ngamring massif, Xigaze ophiolite (Southern Tibet): Implications for the evolution of the Neo-Tethys Ocean","authors":"Gui-Fang Ou ,&nbsp;Zhong’ao Liu ,&nbsp;Wen-Yong Duan ,&nbsp;Guang-Ming Sun ,&nbsp;Xu-Ping Li ,&nbsp;Song-Jie Wang","doi":"10.1016/j.jseaes.2025.106662","DOIUrl":"10.1016/j.jseaes.2025.106662","url":null,"abstract":"<div><div>Rodingites, although volumetrically minor, are integral to the Yarlung Zangbo ophiolites in southern Tibet. However, their tectonic setting, protolith, petrogenesis, and fluid sources remain incompletely understood. This study focuses on rodingites from the Ngamring massif of the Xigaze ophiolite, central Yarlung Zangbo Suture Zone (YZSZ), integrating petrology, mineral and whole-rock geochemistry, and phase equilibrium modeling. The rodingites are structurally heterogeneous and classified into type IA and IB, both featuring metasomatic assemblages of prehnite, chlorite, garnet, and salitic clinopyroxene. Phase equilibrium modeling constrains their formation to low pressure–temperature conditions (&lt;4 kbar and 200–290 °C), while relict magmatic clinopyroxenes with high Mg# values [73–87; Mg# = MgO/(MgO + FeO), with all measured iron considered as FeO] suggest a gabbroic protolith crystallized at ∼ 6.0–7.4 kbar. Both rodingites types display rare earth and multi-element patterns similar to normal mid-ocean ridge basalt (MORB), comparable to other MORB-like rodingites within the Xigaze ophiolite. The host peridotites show trace-element features characteristic of abyssal peridotites, representing residues after ∼ 7–14 % spinel-facies melting of a depleted MORB mantle-like source. The rodingites have variable ⁸⁷Sr/⁸⁶Sr ratios (0.7036–0.7054) and MORB-like ɛNd(<em>t</em>) values (7.3–8.6), suggesting interactions between MOR-derived gabbroic protoliths and serpentinizing fluids derived from the peridotite. Given the presence of metamorphic soles with MORB-type protoliths and both MORB-like and supra-subduction zone magmatic rocks in the YZSZ, it is suggested that the ophiolites likely originated in a MOR environment before evolving into a supra-subduction zone setting as the Neo-Tethys ridge transitioned into an infant subduction system.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106662"},"PeriodicalIF":2.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114932","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":"Updating the timeline of faunal endemism in Balkanatolia, the biogeographic province connecting Europe, Asia and Africa","authors":"Leny Montheil ,&nbsp;Alexis Licht ,&nbsp;Deniz İbilioğlu ,&nbsp;Paul Botté ,&nbsp;Faruk Ocakoğlu ,&nbsp;François Demory ,&nbsp;Gilles Ruffet ,&nbsp;Abel Guihou ,&nbsp;Mustafa Kaya ,&nbsp;Benjamin Raynaud ,&nbsp;Mehmet Serkan Akkiraz ,&nbsp;Pierre Deschamps ,&nbsp;Grégoire Métais ,&nbsp;Pauline Coster ,&nbsp;K. Christopher Beard","doi":"10.1016/j.jseaes.2025.106661","DOIUrl":"10.1016/j.jseaes.2025.106661","url":null,"abstract":"<div><div>Balkanatolia is a Paleogene insular biogeographic province, spanning from southeastern Europe to the Caucasus. It is located at the crossroads of Asia, Europe, and Africa, from which it remained isolated until the late Eocene, fostering endemism, particularly among mammals. However, the timing of emergence of Balkanatolia as an independent biogeographic province remain debated due to the paucity of the fossil record and loose age constraints. Here, we refine this timing by combining magnetostratigraphy, biostratigraphy, geochronology and sedimentology to date three fossil sites of central Anatolia (Çamili Mezra, Ciçekdagi, and Bultu-Zile). These sites have yielded remains of embrithopods, a clade of large herbivorous afrotherian mammals that originated in Africa and dispersed across the Neotethys to reach Balkanatolia where they diversified. The Çamili Mezra locality yield an age spanning from 46.2 Ma to 43.5 Ma, likely around ∼ 45 Ma based on accumulation rates, the Ciçekdagi locality is dated to the very base of Chron C20r (ca. 46.2 Ma) and the Bultu-Zile locality yield overlapping 46.5 ± 1.0 Ma and 45.1 ± 0.9 Ma ages. Overall, these fossil localities are coherently dated to the early Lutetian and represent the oldest unequivocally embrithopod-bearing sites of the northern Neotethysian shores. They provide an early Lutetian minimum age for Balkanatolian endemism, its emergence as an independent biogeographic province and for the overwater dispersal of embrithopods out of Africa.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106661"},"PeriodicalIF":2.7,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084295","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":"Subsurface thermal properties in the deepwater South Makassar Basin, Indonesia","authors":"Feisal Dirgantara ,&nbsp;Susilohadi Susilohadi ,&nbsp;Imam Suyanto ,&nbsp;Mohammad Andri Syahrir Iskandar","doi":"10.1016/j.jseaes.2025.106651","DOIUrl":"10.1016/j.jseaes.2025.106651","url":null,"abstract":"<div><div>Sandwiched between southeastern Kalimantan and southwestern Sulawesi, the widespread presence of bottom simulating reflectors (BSRs) in the deepwater failed rift of the South Makassar Basin strongly indicates the extensive occurence of methane hydrates. Despite the region’s long petroleum exploration history, the understanding of thermal signatures in the basin remains enigmatic. This study utilized thirty-two legacy multi-channel seismic data surveys to derive heat flow, geothermal gradients, and thermal conductivity from BSRs. By assuming the depth range where methane hydrates remain stable, BSRs can act as a proxy for deducing information related to thermal properties when direct thermal measurements are scarce. Estimated thermal properties indicate a mean heat flow of 86 mW/m², a mean geothermal gradient of 73 °C/km, and a mean thermal conductivity of 1.19 W/m.°C at water depth between 400 and 2050 m. These values differ from marine-probe references in the area, with heat flow and thermal conductivity being on average 34 % and 58 % higher, respectively, geothermal gradients being 13 % lower, and geothermal gradients averaging 30 % higher than exploration wells. The variance between the drilling depth at which methane hydrates were penetrated in three exploration wells and the theoretical base of methane hydrate stability zone vary between a deviation of 6–19 m. Discrepancies in thermal properties values and depth of methane hydrates are attributed to methodological disparities, uncertainties in theoretical assumptions, and geological factors such as thermal uplift from the mantle beneath the thinned lithosphere and localized fluid advection.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106651"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084292","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":"Evolution of deep water circulation in the South China Sea since 32 million years ago","authors":"Hao-Wei Huang ,&nbsp;Chih-Hua Chen ,&nbsp;Zhifei Liu ,&nbsp;Kuo-Fang Huang ,&nbsp;Chuan-Hsiung Chung ,&nbsp;Chen-Feng You","doi":"10.1016/j.jseaes.2025.106654","DOIUrl":"10.1016/j.jseaes.2025.106654","url":null,"abstract":"<div><div>The closure of the Indonesian Gateway (IG)<span><span>¹</span></span> has played a pivotal role in influencing interocean circulation, notably affecting the Indonesian Throughflow (ITF) and altering climate patterns in Southeast Asia. However, there remains controversy regarding the timing of IG closure and its impacts on climate changes. In this study, we reconstructed Nd isotope (Ɛ_Nd) time series to observe the evolution of South China Sea (SCS) deep water over the past 32 Ma from core sediments at northern SCS and to explore the deep water connection between Indian Ocean and SCS before the fully IG closure.</div><div>The Ɛ_Nd time series of SCS deep water and benthic δ¹³C composition exhibits a remarkably consistent trend with North Indian Deep Water (NIDW) from 12 to 7 Ma, indicating that NIDW once served as a potential source. This feature implies a deep-water connection between the Indian Ocean and SCS deep water during this period. The observed Ɛ_Nd increases in SCS deep water during key intervals, such as ∼ 11, ∼16, and ∼ 25 Ma, likely link to a reduced contribution of LCDW to SCS deep water. Moreover, the Luzon Strait sill became the sole deep-water pathway into the SCS after IG closure. This restriction may have limited LCDW inflow, potentially intensifying its impacts on SCS deep water, as the LCDW contribution to the SCS has been linked to deep SCS carbon reservoirs. Future studies on high-resolution Ɛ_Nd records in SCS are necessary to explore the timing and climatic implications of this tectonic transition.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"290 ","pages":"Article 106654"},"PeriodicalIF":2.7,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072586","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}