Journal of Asian Earth Sciences最新文献

{"title":"Diverse metamorphic P‒T‒t paths of the Mogutai tectono-metamorphic mélange, eastern Paleozoic Dunhuang Orogenic Belt, northwestern China","authors":"Yan-Lin Zhao ,&nbsp;Yichao Chen ,&nbsp;Xue-Li Jia ,&nbsp;Hui C.G. Zhang ,&nbsp;Zhen M.G. Li ,&nbsp;Longxiang Quek ,&nbsp;Chun-Ming Wu","doi":"10.1016/j.jseaes.2026.106967","DOIUrl":"10.1016/j.jseaes.2026.106967","url":null,"abstract":"<div><div>The Mogutai block, located in the eastern segment of the Paleozoic Dunhuang Orogenic Belt, northwestern China, represents a typical tectono-metamorphic mélange. It exhibits the characteristic block-in-matrix structure, with the matrix being metasedimentary rocks and the tectonic blocks consisting of amphibolite and mafic granulite. Seven representative metamorphic rocks were collected in a limited area with ∼ 1.3 km long and ∼ 1.2 km wide. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating of metamorphic zircon of these rocks reveals that the metamorphic events occurred at ∼ 462‒350 Ma. Different mineral assemblages of the metamorphic rocks were formed sequentially in the three distinct metamorphic stages, i.e., the prograde metamorphism (M1), the peak metamorphism (M2), and the retrograde metamorphism (M3). Diverse clockwise metamorphic pressure − temperature (<em>P − T</em>) paths were reconstructed by geothermobarometry, including the <em>P − T</em> paths of the mafic granulite passing from 4.6 − 6.1 kbar/630 − 650 °C (M1) through 11.9 − 16.3 kbar/710 − 830 °C (M2) and finally to 7.8 − 8.7 kbar/720 − 770 °C (M3), as well as from 6.7 kbar/720 °C (M1) through 8.0 kbar/750 °C (M2) and finally to 4.6 kbar/700 °C (M3) for the garnet amphibolite, respectively. Different peak metamorphic <em>P − T</em> conditions of the metapelitic lenses were estimated to be between 3.7 − 11.9 kbar and 610 − 780 °C. The significant differences in peak <em>P − T</em> conditions of these metamorphic rocks suggest that they were subducted to varying depths during the subduction process, and finally were amalgamated during exhumation, resulting in formation of the Mogutai tectono-metamorphic mélange.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"299 ","pages":"Article 106967"},"PeriodicalIF":2.4,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980917","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 main Paleo-Tethys Ocean suture in the Pamir Region: Revealed by detrital zircon U–Pb geochronology","authors":"Murodov Azamdzhon ,&nbsp;Wei Dan ,&nbsp;Xin Ma ,&nbsp;Murodov Davlatkhudzha ,&nbsp;Sharifjon Odinaev ,&nbsp;Ilhomjon Oimuhammadzoda ,&nbsp;Mustafo Gadoev ,&nbsp;Upendra Baral ,&nbsp;Dzhovid Yogibekov ,&nbsp;Gong-Jian Tang","doi":"10.1016/j.jseaes.2025.106921","DOIUrl":"10.1016/j.jseaes.2025.106921","url":null,"abstract":"<div><div>The Pamir Plateau offers valuable insights into the evolution of the Tethys Oceans. Despite numerous studies, the nature and timing of closure of the Paleo–Tethys Ocean remain debated. This study presents detrital zircon U–Pb ages of sedimentary rocks across the Pamir terranes to investigate their tectonic evolution. Detrital zircons from the Paleozoic–Triassic sedimentary succession in the Northern and Central Pamir yielded similar results, with ages ranging from ∼ 233 Ma to 1000 Ma, showing two major peaks one at ∼ 250 Ma and another at 540–600 Ma. Zircons giving these two age peaks are subhedral to anhedral, implying they were likely derived from arc–related magmatic rocks, possibly formed by the subduction of the Paleo–Tethys oceanic lithosphere. In contrast, detrital zircons from the Late Triassic sandstone in Southern Pamir reveal a major peak at 237 Ma, with subordinate peaks at ∼ 430 Ma and 540 Ma, indicating their detritus was largely sourced from the Central Pamir. Age patterns of the detrital zircons from the Northern–Central Pamir and South Pamir are similar to those of the North and South Qiangtang, respectively, indicating that the Rushan–Pshart suture zone was the main suture of the Paleo–Tethys, and the Tanymas suture zone was the back–arc basin of the Paleo–Tethys Ocean.. The obtained data indicate that the northward subduction of the Paleo–Tethys oceanic lithosphere beneath the Northern and Central Pamir was continuous, at least during the Late Devonian to Triassic period, and the collision between the Central and South Pamir was initiated in the Middle Triassic (∼240 Ma).</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106921"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145808545","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":"Crustal structure of Sulaimaniyah, NE Iraq: Joint analysis of receiver functions and surface wave dispersion","authors":"Suad Mohammed Ali ,&nbsp;Emad H. Al-Khersan ,&nbsp;Hayder I. Mohammed","doi":"10.1016/j.jseaes.2025.106920","DOIUrl":"10.1016/j.jseaes.2025.106920","url":null,"abstract":"<div><div>The Sulaimaniyah region in northeastern Iraq lies within the seismically active Zagros Fold-Thrust Belt (ZFTB), formed by the ongoing collision between the Arabian and Eurasian plates. Despite its tectonic significance, detailed shear-wave velocity models for this area remain scarce, which limits our understanding of the crustal composition, thickness, and deformation mechanisms. This study presents a new, well-constrained crustal structure model for the region, achieved through the novel integration of P-wave receiver functions and Rayleigh wave group velocity dispersion in a joint inversion framework. It also offers an important understanding of the region’s tectonic framework and its significance for hydrocarbon formation and distribution. The aim is to achieve high-resolution constraints on crustal layering and Moho depth beneath the Sulaimaniyah (SLY) seismic station. Data from nine high-quality teleseismic events and 20 carefully selected Rayleigh wave dispersion curves were processed using the Computer Programs in Seismology (CPS) package. The results reveal a four-layered crust: a 10 km-thick sedimentary layer (Vs ≈ 3.1 km/s), an upper crustal layer at 14–16 km (Vs ≈ 3.3 km/s), a mid-crust at 30–32 km (Vs ≈ 3.4–3.5 km/s), and the Moho at ∼ 46 km depth, separating the lower crust (Vs ≈ 3.6 km/s) from the uppermost mantle (Vs ≈ 3.9 km/s). The model also shows a gradational Moho transition, unlike abrupt boundaries observed in some regional sites, suggesting elevated temperatures or crustal fracturing due to active collision processes. This work provides researchers with a robust reference model for the ZFTB sector of Iraq, thereby enhancing seismic hazard assessment, tectonic modelling, and comparative studies of continental collision zones.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106920"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885710","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":"Lithofacies of late cretaceous phosphorite-bearing limestones in the southeastern Turan Block, Afghanistan: implications for paleoenvironmental evolution of the Neo-Tethys","authors":"Attiqullah Ayaz ,&nbsp;Shuang Shi ,&nbsp;Zhenbing She ,&nbsp;Tianyang Li ,&nbsp;Congliang Liu ,&nbsp;Hongjian Zhang ,&nbsp;Mohamad Ehsan Omaid ,&nbsp;Aftab Ur Rahman ,&nbsp;Wei Wang ,&nbsp;Kangjun Huang","doi":"10.1016/j.jseaes.2025.106931","DOIUrl":"10.1016/j.jseaes.2025.106931","url":null,"abstract":"<div><div>The Late Cretaceous Sabzak Phosphorite Formation represents a unique phosphate-bearing succession within Afghanistan’s stratigraphic record, preserving crucial paleoenvironmental archives of Neo-Tethyan oceanic evolution in the North Afghan-Tajik Basin. This study presents pioneering petrographic and microfacies analyses of a 35-meter-thick carbonate succession of the Late Cretaceous period and 1-meter-thick phosphorite-glauconite associations deposited around the Cenomanian-Turonian boundary (∼94 Ma), temporally correlated with the global Oceanic Anoxic Event 2 (OAE-2). Microfacies analysis of distinctive lithologies provides insights into paleoenvironments and sea-level fluctuations within the Cretaceous Neo-Tethys. Thick fossiliferous-oolitic facies, fossiliferous-limestone and phosphorite beds indicate a set of associated environments from the Albian to Early Turonian. This trend was interrupted by a distinctive siliciclastic-enriched facies marking regression during the Late Turonian, followed by bryozoan and coral-rich facies signifying renewed transgression culminating in the Santonian. The Sabzak phosphorite deposit likely has formed under suboxic conditions, as evidenced by the concurrent presence of phosphatic mineralization, exceptional fossil preservation, organic matter accumulation, and widespread glauconitization. A stratified water column is further indicated by benthic foraminifera (e.g., <em>Bulimina aspera</em>) adapted to suboxic bottom waters, contrasting with planktonic foraminifera (<em>Globigerinelloides volutus</em>, <em>Whiteinella archaeocretacea</em>) thriving in productive surface waters. The dominance of the opportunistic species <em>Heterohelix moremani</em> underscores adaptation to extreme conditions. Collectively, our observations provide detailed petrographic and paleontological evidence linking phosphogenesis to OAE-2 redox stratification and elucidating coeval sea-level dynamics within the Neo-Tethys.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106931"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037701","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 mechanisms of lithium isotope fractionation and their influencing factors: Perspectives from small granitic watersheds across different climatic zones in China","authors":"Weihua Wu ,&nbsp;Hao Yang ,&nbsp;Chengxiao Xu ,&nbsp;Werner Nel","doi":"10.1016/j.jseaes.2025.106941","DOIUrl":"10.1016/j.jseaes.2025.106941","url":null,"abstract":"<div><div>Lithium isotopes have rapidly emerged as one of the most promising tracers for silicate weathering. To explore the factors influencing lithium isotope fractionation, we investigated small granitic watersheds across various climatic zones in China. Watersheds in the western Sichuan Plateau and cold–temperate Amur River basin exhibit the lowest chemical weathering rates (CWR), while those in tropical Hainan exhibit CWR values approximately ten times higher. Additionally, CWR in the Hainan watersheds is three times greater than those in the tropical Jinghong watersheds with lower runoff. A “boomerang” relationship (parabolic-like, low–high-low) is observed between CWR and dissolved Li isotope ratios (δ⁷Li_diss). Conversely, weathering intensity, expressed as the chemical index of alteration (CIA), shows a corresponding high–low–high trend with δ⁷Li values in the clay fraction of riverbed sediments (δ⁷Li_clay). The trends for CWR vs. δ⁷Li_diss and CIA vs. δ⁷Li_clay differ noticeably. Although watersheds in the western Sichuan Plateau region and Amur River basin share similarly low CWR, their weathering intensity and δ⁷Li_diss values fluctuate, indicating that factors beyond climate climate—such as topography and vegetation— affect physical erosion, weathering intensity, and Li isotope fractionation. At high CWR, δ⁷Li_diss decreases by about 8 ‰ (from +31.6 ‰ to +23.7 ‰), whereas weathering intensity and δ⁷Li_clay remain stable, likely due to dissolution-precipitation and adsorption–desorption processes. Given the complexity of Li isotope behavior during weathering, we conclude that using Li isotopes to trace weathering intensity requires a comprehensive evaluation of climate, topography, water–rock interaction time, and clay mineral composition.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106941"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885709","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":"Depositional environments of a mixed siliciclastic-carbonate system: A case study of the late Ediacaran sedimentary succession in the northern Sichuan Basin (SW China)","authors":"Junxin Shang ,&nbsp;Mingyou Feng ,&nbsp;Xingzhi Wang ,&nbsp;Maolong Xia ,&nbsp;Yong Li ,&nbsp;Junlang Chen ,&nbsp;Chao Zhang ,&nbsp;Xiaohong Liu","doi":"10.1016/j.jseaes.2025.106942","DOIUrl":"10.1016/j.jseaes.2025.106942","url":null,"abstract":"<div><div>The limited understanding of late Ediacaran mixed carbonate-siliciclastic sedimentary systems in the northern Sichuan Basin poses challenges for reconstructing the paleogeographic configuration. This study investigated outcrops of the Labagang and Dengying Formations in the region to develop a depositional model and identify controlling factors. Detailed sedimentological observations led to the identification of eleven lithofacies dominated by rimmed platform deposits and eight lithofacies dominated by siliciclastic-rich platform deposits, which were grouped into six facies associations, representing two distinct sedimentary models: rimmed platform and siliciclastic-dominated platform. Based on sedimentological analysis, log datasets, and chronostratigraphic data, two third-order sequences with transgressive systems tract (TST) and highstand systems tract (HST) were established. During TST1 and TST2, the Labagang Formation and the third member of the Dengying Formation were dominated by siliciclastic-rich deposits, classified into inner platform, middle platform, and outer platform facies associations. These sequences were interpreted as representing two separate flooding events that affected the depositional architecture and facies distribution of the platform. In contrast, during HST1 and HST2, the second and fourth members of the Dengying Formation were primarily composed of carbonate-rich deposits, categorized into peritidal to lagoon, microbialite reef complex, and slope to siliceous basin facies associations, associated with a slow sea-level fall following transgression. These third-order sequences, primarily controlled by regional sea-level changes, may also reflect episodic tectonic activity. Sustained plate convergence likely reactivated fault-related structures inherited from earlier rifting, leading to regional subsidence and flooding events.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106942"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885702","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":"SHRIMP U-Pb zircon ages and geochemistry of Jian forsterite jade from Jilin province, North-eastern China","authors":"Bijie Peng ,&nbsp;Mingyue He ,&nbsp;Mei Yang ,&nbsp;Ning Wang","doi":"10.1016/j.jseaes.2025.106944","DOIUrl":"10.1016/j.jseaes.2025.106944","url":null,"abstract":"<div><div>The Jian forsterite jade, a recently discovered gemological variety from Northeast China, is characterized by attractive coloration and fine-grained texture. The formation age and ore-forming materials provenance of the jade deposit remain unconstrained, posing significant obstacles to understanding its genesis. In this study, we conducted petrography, whole-rock geochemistry, and zircon U-Pb geochronology analyses of Jian forsterite jade using X-ray fluorescence spectroscopy (XRF), Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS), and Sensitive High-Resolution Ion Micro Probe (SHRIMP). The whole-rock geochemical data show high MgO contents with relative depletion in Cr, Co, and Ni. The chondrite-normalized REE patterns, characterized by LREE enrichment and HREE depletion, closely resemble those of marble, supporting a protolith of magnesium-rich dolomitic marble. Boron isotope compositions of forsterite (5.11 ‰–6.91 ‰) from the Jian forsterite jade overlap with that of boron-rich minerals from adjacent boron deposits, indicating that the source of boron is related to the enrichment of boron in the Paleoproterozoic Ji’an Group strata. SHRIMP U-Pb dating of zircons from the Jian forsterite jade yield concordant ages of 420.4 ± 8.6 Ma to 439.4 ± 8.8 Ma, which provide a maximum age constraint for the formation timing of the jade deposit. Based on the geochemical and geochronological evidence, we propose that the Jian forsterite jade deposit is of hydrothermal metasomatic origin. During the prograde metamorphism, silica-rich hydrothermal fluids reacted with the Mg-rich carbonates to form forsterite. Subsequently, forsterite was metasomatized by boron-rich fluids, which induced different degrees of serpentinization, ultimately generating the Jian forsterite jade deposit.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106944"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885705","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":"Mass transport deposits in confined environment, a case study from the Kaiping sag, Pearl River Mouth basin, northern south China sea margin","authors":"Lushan Jiang,&nbsp;Xiwu Luan","doi":"10.1016/j.jseaes.2025.106924","DOIUrl":"10.1016/j.jseaes.2025.106924","url":null,"abstract":"<div><div>Mass transport deposits (MTDs) have been extensively discussed in the literature. The prevailing understanding characterizes MTDs as gravity-driven instability phenomena occurring on the seafloors. This study employs high-resolution 2D/3D seismic data integrated with well data to re-evaluate the genesis mechanisms of MTDs in the Kaiping sag, Zhu-II depression, Pearl River Mouth basin (PRMB), northern margin of the South China Sea (SCS). Key diagnostic features interpreted from seismic datasets reveal the absence of typical characteristics of conventional MTDs, including no distinct headwall scarps, and moats, and especially no onlapping structures of isochronous turbidite contourites that usually cover uneven MTD surfaces. In contrast, seismic evidence for a<!--> <!-->tectonic compression environment<!--> <!-->is observed, such as thrust fault reactivation, localized stratal folding, and chaotic thrust-related deformation patterns within the study interval-consistent with the post-spreading tectonic setting of the SCS. For the first time, this research concludes that these MTDs formed in a confined environment (rather than an open continental slope), and were induced by mega-earthquakes. The key contributing factors to their formation include: (1) tectonic compression after the cessation of SCS seafloor spreading (post-16 Ma), evidenced by seismic records of thrusting and folding; (2) elevated sedimentation rates since the peak uplift of the eastern Tibetan plateau (since 15 Ma), leading to thick unconsolidated sediments; (3) periods of higher sea level (favouring high pore-water pressure); and (4) mega-earthquakes triggered by the post-spreading compression. Collectively, these factors facilitated the liquefaction processes that drove MTDs development.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106924"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145842641","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":"Fe occupancy in zoned ferroan dolomite and its constraints on dolomite ordering process: a case study on micritic dolostone of Ordovician Majiagou formation in eastern Ordos Basin, China","authors":"Zhenmeng Sun ,&nbsp;Xiangjie Cui ,&nbsp;Xin Liu ,&nbsp;Huan Liu ,&nbsp;Xiancai Lu","doi":"10.1016/j.jseaes.2025.106915","DOIUrl":"10.1016/j.jseaes.2025.106915","url":null,"abstract":"<div><div>The cation ordering mechanism and their influence on crystal structure evolution remain poorly understood. This study investigates the oscillatory zoned ferroan dolomite within moldic pores of micritic dolostone from the Ordovician Majiagou Formation in the eastern Ordos Basin, focusing on the site preference, distribution patterns of Fe in the dolomite structure, and its impact on the cation ordering process. Results show that from core to rim, the zoning exhibits increasing Fe content (0.27 mol%, 7.36 mol%, 10.55 mol%) with a corresponding decrease in Mg. Fe substitution primarily influences M–O bond lengths, leading to systematic changes in unit cell parameters: the <em>a/b</em> lattice parameters increase from 4.8066 Å to 4.8234 Å, the <em>c</em> lattice parameter from 16.0051 Å to 16.0690 Å, and the unit cell volume expands by approximately 1.1 %. Uniform strontium isotope compositions of the three zones indicate a homogeneous pore fluid derived from seawater. Further analysis via EXAFS spectroscopy, AC-TEM observation, and DFT calculations confirms that Fe²⁺ preferentially occupies Mg sites and tends to aggregate within Mg layers, forming nanoscale modulated structures and ordered domains. This causes local lattice distortion and defects, reducing the cation ordering degree from 0.45 to 0.30, while these regions may act as preferential sites for ordering progression. The study suggests that local migration and redistribution of trace elements in dolomite may facilitate structural ordering evolution. These findings provide a new crystal defect dynamics perspective for interpreting dolomite structural evolution, contributing to a better understanding of the “dolomite problem”.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106915"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145885703","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 responses and principal controlling factors of evaporative fractionation in crude oils from the Yinggehai and Qiongdongnan basins, South China Sea, China","authors":"Anliang Liu ,&nbsp;Lifang Wang ,&nbsp;Zhihong Chen ,&nbsp;Xinquan Liang ,&nbsp;Hong Lu","doi":"10.1016/j.jseaes.2025.106939","DOIUrl":"10.1016/j.jseaes.2025.106939","url":null,"abstract":"<div><div>Evaporative fractionation has been recognized as a pivotal mechanism shaping hydrocarbon accumulation, yet the precise geochemical fingerprints and underlying controls of this process remain incompletely resolved. Here, we present an integrated geochemical investigation of crude oils from both basins, utilizing whole-oil chromatograms, light hydrocarbon and <em>n</em>-alkane distributions, diamondoid compositions, and stable carbon isotopic signatures, in conjunction with regional tectonic and geological analyses. Our findings reveal that crude oils throughout both basins have experienced diverse degrees of evaporative fractionation, as evidenced by the preferential depletion of low-carbon-number <em>n</em>-alkanes and adamantanes in concert with migrating natural gas, together with enrichment of aromatic hydrocarbons and diamantanes. These alterations generate a negative correlation between the ratio of adamantane-to-diamantane (As/Ds) and <em>n</em>-alkanes mass depletion, while the loss of light compositions gives rise to heavier δ¹³C values of whole-oil. This manifests clearly as an inverted “V-shaped” isotopic profile among the saturates, whole oil, and aromatic hydrocarbon fractions, which offers a robust geochemical indicator of evaporative fractionation. Petroleum system analysis indicates that this process is primarily governed by three factors: (1) abundant source rocks, which provide the requisite supply of light hydrocarbons; (2) distinct hydrocarbon migration networks, including vertical diapiric conduits and faults; and (3) the effects of late-stage charging by highly-mature natural gas, often in association with episodic reservoir leakage.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106939"},"PeriodicalIF":2.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978236","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}