Journal of Asian Earth Sciences最新文献_第3页

Early Carboniferous tectonic setting of the Kalamaili suture Zone, north Junggar (NW China): Constraints from the volcanic rocks in the geological section of Songkaersu Formation 准噶尔北部卡拉麦里缝合带早石炭世构造背景：松凯尔苏组地质剖面火山岩的约束

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2026-01-03 DOI: 10.1016/j.jseaes.2026.106950

Qianru Cai , Jinduo Wang , Guanlong Zhang , Zhengrong Xiong , Hongzhou Yu , Jian Zhou , Zhihua Song

The mid-Early Carboniferous period characterized by widespread magmatism represents a key tectonic transition stage for the Kalamaili suture zone of Northeastern Junggar. Debates persist on the petrogenesis and tectonic setting of these Early Carboniferous igneous rocks, restricting our understanding of the Late Paleozoic tectonic evolution. In this study, we performed integrated geochronological and geochemical analyses on intermediate-basic volcanic rocks of the Songkaersu Formation from the Shuangjingzi North and Xidagou South profiles along the southern Kalamaili suture zone. Zircon U-Pb dating of three samples constrains magmatic activity to 344–332 Ma. The rocks comprise basalt, basaltic andesite, and andesite, exhibiting calc-alkaline affinity. Their geochemical compositions demonstrate variable SiO₂ (46.76–62.87 wt%), MgO (1.49–6.42 wt%), and K₂O (0.23–3.68 wt%), moderate TiO₂ (0.42–1.19 wt%), and elevated Na₂O (2.89–5.85 wt%) and P₂O₅ (0.21–0.59 wt%) contents. Enrichment in large-ion lithophile elements (LILEs: Rb, Ba, K) and light rare earth elements (LREEs), coupled with depletion in high-field-strength elements (HFSEs: Nb, Ta, Ti), suggests arc-related affinity. Radiogenic isotope signatures reveal low initial ⁸⁷Sr/⁸⁶Sr ratios (0.7039–0.7043) and significant variations in ε_Nd (t) (+5.0 – +7.5) and ε_Hf (t) values (+0.05 – +12.62). These features imply derivation from partial melting of previously subducted slab-derived fluids metasomatized depleted mantle lithosphere. The integrated geochemical and isotopic patterns, combined with evidence of mantle material upwelling driven by lithospheric thinning, indicate a post-collisional intraplate tectonic setting. Collectively, these results suggest that the northeastern Junggar Basin transitioned to a post-collisional regime by at least the middle Early-Carboniferous.

中早石炭世是准噶尔东北部卡拉麦里缝合带的重要构造过渡时期，岩浆活动广泛存在。这些早石炭世火成岩的成因和构造背景一直存在争议，限制了我们对晚古生代构造演化的认识。本文对沿卡拉麦里缝合带南部双井子北剖面和西大沟南剖面松凯尔苏组中基性火山岩进行了年代学和地球化学综合分析。三个样品的锆石U-Pb定年限制了岩浆活动在344 ~ 332 Ma之间。岩石包括玄武岩、玄武岩安山岩和安山岩，具有钙碱性亲和力。其地球化学成分表现为SiO2 （46.76 ~ 62.87 wt%）、MgO （1.49 ~ 6.42 wt%）、K2O （0.23 ~ 3.68 wt%）含量变化，TiO2 （0.42 ~ 1.19 wt%）含量适中，Na2O （2.89 ~ 5.85 wt%）和P2O5 （0.21 ~ 0.59 wt%）含量升高。大离子亲石元素（LILEs: Rb, Ba， K）和轻稀土元素（LREEs）富集，高场强元素（hfse: Nb, Ta, Ti）耗损，表明弧相关亲和力。放射性成因同位素特征显示，初始87Sr/86Sr比值（0.7039 ~ 0.7043）较低，εNd (t)（+5.0 ~ +7.5）和εHf (t)值（+0.05 ~ +12.62）变化显著。这些特征意味着源自先前俯冲的板块衍生流体的部分熔融，这些流体交代了枯竭的地幔岩石圈。综合地球化学和同位素模式，结合岩石圈变薄驱动的地幔物质上涌的证据，表明了碰撞后的板内构造背景。总之，这些结果表明，准噶尔盆地东北部至少在早石炭世中期过渡到后碰撞状态。

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引用次数: 0

The Earth magnetic field in the Mesoproterozoic – a new assessment of paleomagnetic secular variation from Arctic Siberia, Russia 中元古代地球磁场——对俄罗斯西伯利亚北极地区古地磁长期变化的新评价

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2026-01-03 DOI: 10.1016/j.jseaes.2026.106951

Aleksandr Pasenko , Ivan Lebedev , Dmitrii Ushakov

The hypothesis that the Earth’s magnetic field can be approximated by a time-averaged geocentric axial dipole (GAD) allows paleomagnetic data to be used in developing paleogeographic reconstructions. For the Precambrian, this hypothesis needs to be tested for different time intervals. On the other hand, information on the evolution of the geomagnetic field during the Precambrian can be used to shed light on the processes of deep geodynamics and the evolution of the Earth’s core. One of the numerical parameters characterizing the state of the geomagnetic field is the amplitude of the paleosecular variations (PSV), estimated from the scatter of the directions of the natural remanent magnetization. We propose a new estimate of PSV amplitude calculated for low latitudes of ∼1.5 Ga over 36 individual sites, which is unique for such determinations in the Precambrian. Our new estimate of S_b =

10.2 \frac{13.0}{9.5}

° is consistent with recent G-models for Precambrian. It indicates that in the Mesoproterozoic, the contribution of symmetric magnetic field components to geomagnetic variations was comparable to the Mesozoic and to the present-day.

地球磁场可以用时间平均地心轴向偶极子（GAD）来近似的假设，使得古地磁数据可以用于发展古地理重建。对于前寒武纪，这个假设需要在不同的时间间隔内进行检验。另一方面，关于前寒武纪地磁场演化的信息可以用于揭示深部地球动力学过程和地核演化。表征地磁场状态的数值参数之一是古长期变化幅度（PSV），它是由自然剩余磁化方向的散射估计的。我们提出了一个新的估计，在36个单独的地点上计算了低纬度~ 1.5 Ga的PSV振幅，这在前寒武纪的此类确定中是独一无二的。我们对Sb = 10.213.09.5°的新估计与最近的前寒武纪g模型一致。表明在中元古代，对称磁场分量对地磁变化的贡献与中生代和现代相当。

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引用次数: 0

Integrated seismic hazard assessment around Qom City, North-Central Iran, based on earthquake focal mechanisms, fault-slip data, and deterministic analysis 基于震源机制、断层滑动数据和确定性分析的伊朗中北部库姆市周边地震危险性综合评估

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2026-01-02 DOI: 10.1016/j.jseaes.2025.106945

Mohadese Ajami, Abdollah Sohrabi-Bidar, Reza Nozaem

Iran is located in the central part of the Alpine-Himalayan orogenic belt, experiencing significant and destructive earthquakes throughout its history. Obviously, major and strategically important cities hold great significance in the event of an earthquake, considering their political and social importance. Among the important cities of Iran, Qom is a populous and significant city in the northern part of the central Iranian zone. This paper presents a seismotectonic assessment by examining and analyzing seismic and fault-slip data to determine the average attitude of the principal stress tensors within a 150 km radius of Qom city. Next, these findings were integrated with the results of deterministic seismic analysis and utilized in the Fault Motion Potential (FMP) method to evaluate the risk level of major surrounding faults in Qom. Modern and paleostress assessments determined that the trend of the maximum principal stress axis is about N30E, approximately aligning with the current convergence of the Arabian-Eurasian plates in central Iran. Consequently, under such a dominant stress regime, the movement capacity of a fault is directly linked to the relation between fault geometry and the main stress axes. Furthermore, fault length and its distance to the site are key parameters for assessing the potential seismic hazard based on the evaluation of a Deterministic risk event. Deterministic risk study identified Qom, Alborz, and Haji-Abad faults as the most seismic risk influencing factors in the region. Fault motion potential (FMP) values were computed for these faults by using modern and paleostress data with respect to each fault pole geometry. The outcome of our study indicated that the Qom and Alborz faults have high reactivation potential for earthquake generation, with FMP values of 0.6 and 0.7, respectively. In contrast, the Haji-Abad fault, with an FMP value of 0.3, represents a moderate seismic risk level. Earthquakes that occur along this fault can reach magnitudes up to 7.2 Mw. The results of this research can be used in the urban development programming of Qom, and adjacent areas.

伊朗位于阿尔卑斯-喜马拉雅造山带的中部，在其历史上经历了重大和破坏性的地震。显然，考虑到它们的政治和社会重要性，具有重要战略意义的大城市在地震事件中具有重要意义。在伊朗的重要城市中，库姆是伊朗中部地区北部人口众多的重要城市。本文通过对地震和断层滑动资料的检查和分析，提出了一种地震构造评价方法，以确定库姆市半径150公里范围内主应力张量的平均姿态。然后，将这些发现与确定性地震分析结果相结合，应用于断层运动势（FMP）方法评价库姆周边主要断层的风险等级。现代和古应力评估表明，最大主应力轴的走向约为N30E，与目前阿拉伯-欧亚板块在伊朗中部的汇聚方向大致一致。因此，在这种主导应力状态下，断层的运动能力与断层几何形状与主应力轴之间的关系直接相关。此外，基于确定性风险事件的评价，断层长度和断层到场地的距离是评估潜在地震危险性的关键参数。确定性风险研究确定Qom、Alborz和Haji-Abad断裂是该地区地震风险影响最大的因素。利用现代和古应力资料，根据各断裂极的几何形状计算了断层运动电位。研究结果表明，库姆断裂和阿尔博斯断裂具有较高的地震再激活潜力，FMP值分别为0.6和0.7。相比之下，Haji-Abad断层的FMP值为0.3，代表中等地震风险等级。沿着这条断层发生的地震震级可达7.2兆瓦。研究结果可用于库姆及邻近地区的城市发展规划。

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引用次数: 0

Early Devonian alkaline volcanism in the North Qaidam, NW China: Insights into the Proto- to Paleo-Tethys tectonic transition 柴达木北部早泥盆世碱性火山作用：对原-古特提斯构造转变的认识

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2026-01-01 DOI: 10.1016/j.jseaes.2025.106946

Mao Wang , Xianzhi Pei , Lei Pei , Zuochen Li , Chengjun Liu , Lili Xu , Ruibao Li , Li Qin , Xiao Wang , Nan Hu , Hao Lin

The North Qaidam (NQ) preserves records of Paleozoic to Early Mesozoic magmatic activity and metamorphism, reflecting a complex multi-stage tectonic evolution. The Maoniushan Formation is a key stratigraphic record of the Proto- to Paleo-Tethys transition. We present petrological, zircon U-Pb geochronological, whole-rock geochemical, and Lu-Hf isotopic data for Maoniushan Formation alkaline volcanics in the Xiatuoaer area. The suite comprises basalt, basaltic andesite, and trachyte. Zircon U-Pb geochronology indicates an Early Devonian eruption age (ca. 403 – 400 Ma). Geochemically, the suite is shoshonitic, enriched in LREEs, and depleted in HREEs and HFSEs (e.g., Nb, Ta, P, Ti). Their ε_Hf(t) values range from −11.4 to + 6.8, predominantly negative (−11.4 to −3.4), indicating a mixed mantle source dominated by enriched mantle. Petrographic and geochemical data indicate the basalts originated from low-degree partial melting of a mixed, fluid-metasomatized lithosphere mantle with a minor asthenosphere component. The trachytes resulted from mixing of mantle-derived mafic magmas and crustal-derived felsic melts. Integrated regional geological data indicate the NQ subcontinental mantle was metasomatized by slab-derived fluids during Proto-Tethys oceanic subduction. During the Early Devonian, lithosphere delamination and remote response to back-arc extension in the Paleo-Tethys main ocean (Qiangtang area) triggered partial melting of this metasomatized mantle, generating the Maoniushan Formation alkaline volcanics. This magmatic event marks the onset of extensional collapse of the southern Proto-Tethys orogenic belt in the NQ, indicating the terminal stage of its tectonic cycle. Concurrent development of a local aulacogen (initial rift) along the northern NQ indicates the initial transition into the Paleo-Tethys domain.

柴达木北部保存了古生代至早中生代的岩浆活动和变质作用记录，反映了一个复杂的多期构造演化过程。毛牛山组是古特提斯向原特提斯过渡的重要地层记录。本文报道了下沱尔地区毛牛山组碱性火山岩的岩石学、锆石U-Pb年代学、全岩地球化学和Lu-Hf同位素资料。该套由玄武岩、玄武岩安山岩和粗面岩组成。锆石U-Pb年代学显示早泥盆世喷发时代（约403 ~ 400 Ma）。地球化学特征表明，该岩组为高玄石质，低稀土元素富集，低稀土元素和高稀土元素（如Nb、Ta、P、Ti）富集。它们的εHf(t)值在- 11.4 ~ + 6.8之间，以负的（- 11.4 ~ - 3.4）为主，表明地幔源以富集地幔为主。岩石学和地球化学资料表明，玄武岩起源于混合流体交代岩石圈地幔的低程度部分熔融，软流圈成分较少。粗纤维岩是幔源性基性岩浆与壳源性长英质熔体混合形成的。综合区域地质资料表明，北q次大陆地幔在原特提斯洋俯冲过程中受到了板块流体的交代作用。早泥盆世，古特提斯主洋（羌塘地区）的岩石圈拆沉和弧后伸展的远程响应引发了该交代地幔的部分熔融，形成了毛牛山组碱性火山。这一岩浆事件标志着南原特提斯造山带在NQ伸展坍缩的开始，标志着南原特提斯造山带进入构造旋回的终末阶段。北秦岭北部同时发育一个局部裂陷槽（初始裂谷），标志着古特提斯域的初始过渡。

{"title":"Early Devonian alkaline volcanism in the North Qaidam, NW China: Insights into the Proto- to Paleo-Tethys tectonic transition","authors":"Mao Wang , Xianzhi Pei , Lei Pei , Zuochen Li , Chengjun Liu , Lili Xu , Ruibao Li , Li Qin , Xiao Wang , Nan Hu , Hao Lin","doi":"10.1016/j.jseaes.2025.106946","DOIUrl":"10.1016/j.jseaes.2025.106946","url":null,"abstract":"<div><div>The North Qaidam (NQ) preserves records of Paleozoic to Early Mesozoic magmatic activity and metamorphism, reflecting a complex multi-stage tectonic evolution. The Maoniushan Formation is a key stratigraphic record of the Proto- to Paleo-Tethys transition. We present petrological, zircon U-Pb geochronological, whole-rock geochemical, and Lu-Hf isotopic data for Maoniushan Formation alkaline volcanics in the Xiatuoaer area. The suite comprises basalt, basaltic andesite, and trachyte. Zircon U-Pb geochronology indicates an Early Devonian eruption age (ca. 403 – 400 Ma). Geochemically, the suite is shoshonitic, enriched in LREEs, and depleted in HREEs and HFSEs (e.g., Nb, Ta, P, Ti). Their ε<sub>Hf</sub>(t) values range from −11.4 to + 6.8, predominantly negative (−11.4 to −3.4), indicating a mixed mantle source dominated by enriched mantle. Petrographic and geochemical data indicate the basalts originated from low-degree partial melting of a mixed, fluid-metasomatized lithosphere mantle with a minor asthenosphere component. The trachytes resulted from mixing of mantle-derived mafic magmas and crustal-derived felsic melts. Integrated regional geologicaldata indicatethe NQ subcontinental mantle was metasomatized by slab-derived fluids during Proto-Tethys oceanic subduction. During the Early Devonian, lithosphere delamination and remote response to back-arc extension in the Paleo-Tethys main ocean (Qiangtang area) triggered partial melting of this metasomatized mantle, generating the Maoniushan Formation alkaline volcanics. This magmatic event marks the onset of extensional collapse of the southern Proto-Tethys orogenic belt in the NQ, indicating the terminal stage of its tectonic cycle. Concurrent development of a local aulacogen (initial rift) along the northern NQ indicates the initial transition into the Paleo-Tethys domain.</div></div>","PeriodicalId":50253,"journal":{"name":"Journal of Asian Earth Sciences","volume":"298 ","pages":"Article 106946"},"PeriodicalIF":2.4,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939824","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}

引用次数: 0

Depositional environments of a mixed siliciclastic-carbonate system: A case study of the late Ediacaran sedimentary succession in the northern Sichuan Basin (SW China) 硅-塑-碳酸盐岩混合体系沉积环境——以四川盆地北部晚埃迪卡拉世沉积演替为例

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-29 DOI: 10.1016/j.jseaes.2025.106942

Junxin Shang , Mingyou Feng , Xingzhi Wang , Maolong Xia , Yong Li , Junlang Chen , Chao Zhang , Xiaohong Liu

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.

四川盆地北部晚埃迪卡拉世碳酸盐-硅屑混合沉积体系的认识有限，给古地理构型的重建带来了挑战。通过对该地区拉巴岗组和灯影组露头的研究，建立了沉积模式，并确定了控制因素。通过详细的沉积学观察，确定了以边缘台地沉积为主的11个岩相和以富含硅屑碎屑台地沉积为主的8个岩相，并将其划分为6个相组，代表了两种不同的沉积模式：边缘台地和硅屑碎屑台地。根据沉积学分析、测井资料和年代地层资料，建立了海侵体系域（TST）和高位体系域（HST）两个三级层序。TST1和TST2期间，拉巴岗组和灯影组三段以富硅屑沉积为主，分为内台地、中台地和外台地相组合。这些层序被解释为代表了两个独立的洪水事件，影响了台地的沉积构型和相分布。而在HST1和HST2时期，灯影组二段和灯影组四段主要为富碳酸盐沉积，分为潮滩-泻湖相、微生物岩礁复合体和斜坡-硅质盆地相组合，并伴有海侵后缓慢的海平面下降。这些三级层序主要受区域海平面变化控制，也可能反映幕式构造活动。持续的板块收敛可能重新激活了从早期裂陷中继承下来的与断层有关的构造，导致了区域下沉和洪水事件。

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引用次数: 0

Precambrian crustal evolution of the southern margin of the North China Craton: Evidence from the Paleo–Mesoproterozoic sedimentary rock 华北克拉通南缘前寒武纪地壳演化：来自古-中元古代沉积岩的证据

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-29 DOI: 10.1016/j.jseaes.2025.106943

Shuo Wang , De-Bin Yang , Xiang-Yu Yan , Ke Wu , Jian-Ning Liu , Rui-Qing Xue

Clastic sedimentary rocks offer crucial insights for deciphering the Precambrian crustal evolution. Paleo–Mesoproterozoic sedimentation is widely developed in the southern margin of the North China Craton (SNCC). Previous research has primarily concentrated on magmatism, while the information of Precambrian crustal evolution revealed by sedimentary rocks was less concerned. Hence, we present the zircon U–Pb ages, zircon Hf isotopes and whole-rock geochemical data of the quartz sandstones from the Beidajian Formation of the Ruyang Group, the Sanjiaotang Formation of the Luoyu Group and the Ma’anshan and Luotuopan formations of the Wufoshan Group within the SNCC. The detrital zircon dating, Hf isotope data and geochemical features of these formations indicate that their sediments were primarily sourced from the Neoarchean–Paleoproterozoic rock units in the SNCC, with the characteristics of mature crustal materials. Their detrital zircon age spectra and depositional environment combined with geological evidence indicate that the SNCC was in an extensional environment during the late Paleoproterozoic to early Mesoproterozoic. The Hf isotope data combined with geological evidence suggest that the crustal growth was dominant in the SNCC during the early Neoarchean (2.80–2.70 Ga), and the crustal reworking played a dominant role during the mid- to late Paleoproterozoic (2.00–1.72 Ga), while the crustal growth and reworking coexisted during the late Neoarchean (ca. 2.50 Ga) and early to mid-Paleoproterozoic (2.46–2.02 Ga).

碎屑沉积岩为破译前寒武纪地壳演化提供了至关重要的见解。华北克拉通南缘古-中元古代沉积广泛发育。以往的研究主要集中在岩浆活动方面，沉积岩揭示的前寒武纪地壳演化信息较少。在此基础上，给出了北洋群北大尖组、罗屿群三角塘组、五佛山群马鞍山组和骆驼滩组石英砂岩的锆石U-Pb年龄、锆石Hf同位素和全岩地球化学数据。碎屑锆石定年、Hf同位素数据和地球化学特征表明，这些地层的沉积物主要来自SNCC的新太古代-古元古代岩石单元，具有成熟的地壳物质特征。其碎屑锆石年龄谱和沉积环境结合地质证据表明，在古元古代晚期至中元古代早期，SNCC处于伸展环境。Hf同位素资料结合地质证据表明，SNCC在新太古代早期（2.80 ~ 2.70 Ga）以地壳生长为主，在古元古代中晚期（2.00 ~ 1.72 Ga）以地壳改造为主，而在新太古代晚期（约2.50 Ga）和古元古代早期至中期（2.46 ~ 2.02 Ga）地壳生长和改造同时存在。

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引用次数: 0

SHRIMP U-Pb zircon ages and geochemistry of Jian forsterite jade from Jilin province, North-eastern China 吉林省剑长石玉石SHRIMP U-Pb锆石年龄及地球化学特征

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-28 DOI: 10.1016/j.jseaes.2025.106944

Bijie Peng , Mingyue He , Mei Yang , Ning Wang

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.

摘要近年来在中国东北地区发现的一种宝石品种——坚橄榄石玉，具有色泽鲜艳、纹理细腻的特点。玉石矿床的形成年代和成矿物质来源尚无定论，对其成因的认识存在较大障碍。本文采用x射线荧光光谱（XRF）、激光烧蚀多集电极电感耦合等离子体质谱（LA-MC-ICP-MS）和高分辨率离子微探针（SHRIMP）等技术，对剑锋石玉石进行了岩石学、全岩地球化学和锆石U-Pb年代学分析。全岩地球化学数据显示MgO含量高，Cr、Co、Ni相对富集。球粒陨石归一化稀土模式与大理岩相似，表现为轻稀土富集和重稀土亏缺，支持富镁白云质大理岩原岩。吉安岩体玉石中富硼矿物硼同位素组成（5.11‰~ 6.91‰）与邻近硼矿床富硼矿物硼同位素组成重叠，表明硼的来源与古元古代吉安群地层中硼的富集有关。对剑山橄榄石玉石锆石SHRIMP U-Pb定年结果显示，锆石年龄在420.4±8.6 ~ 439.4±8.8 Ma之间，为该玉石矿床的形成时间提供了最大年龄约束。综合地球化学和年代学的证据，认为吉安森林石玉石矿床为热液交代成因。在进变质作用过程中，富硅热液与富镁碳酸盐相互作用，形成富镁碳酸盐。随后，富硼流体对橄榄石进行交代作用，诱发不同程度的蛇纹石成矿作用，最终形成坚橄榄石玉石矿床。

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引用次数: 0

The mechanisms of lithium isotope fractionation and their influencing factors: Perspectives from small granitic watersheds across different climatic zones in China 锂同位素分馏机制及其影响因素——来自中国不同气候带花岗岩小流域的视角

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-25 DOI: 10.1016/j.jseaes.2025.106941

Weihua Wu , Hao Yang , Chengxiao Xu , Werner Nel

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.

锂同位素已迅速成为最有希望的硅酸盐风化示踪剂之一。为了探讨锂同位素分馏的影响因素，我们对中国不同气候带的小花岗岩流域进行了研究。川西高原和寒温带阿穆尔河流域流域的化学风化速率（CWR）最低，而热带海南流域的CWR值高约10倍。此外，海南流域的CWR是热带景洪流域的3倍，径流较少。在CWR和溶解Li同位素比值（δ7Lidiss）之间观察到一个“回飞器”关系（抛物线状，低-高-低）。相反，风化强度以蚀变化学指数（CIA）表示，与河床沉积物粘土组分（δ7Liclay）的δ7Li值呈相应的高-低-高趋势。CWR相对于δ7Lidiss和CIA相对于δ7Liclay的趋势差异显著。虽然川西高原区和黑龙江流域流域的CWR相似，但其风化强度和δ7Lidiss值存在波动，表明气候以外的因素（如地形和植被）影响了物理侵蚀、风化强度和Li同位素分异。在高CWR时，δ7Lidiss减小了约8‰（从+31.6‰降至+23.7‰），而风化强度和δ7Liclay保持稳定，这可能是溶蚀-沉淀和吸附-解吸过程的结果。考虑到Li同位素在风化过程中的复杂性，我们认为利用Li同位素追踪风化强度需要综合评估气候、地形、水岩相互作用时间和粘土矿物组成。

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引用次数: 0

The rupture process of the September 2022 Guanshan and Chishang Earthquakes: Joint inversion of seismological and geodetic data 2022年9月关山和赤上地震破裂过程：地震和大地测量资料联合反演

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-25 DOI: 10.1016/j.jseaes.2025.106940

Wei-Yu Zhang , Yu-Sheng Sun , Yopi Serhalawan , Po-Fei Chen , Ming-Che Hsieh , Wu-Lung Chang

On 17–18 September 2022, the Mw 6.5 Guanshan and Mw 7.0 Chishang earthquakes, struck the Longitudinal Valley (LV) of Taiwan, the collision boundary between the Eurasian plate and the Philippine Sea plate. Aftershock patterns show that the events occurred within 24 h, only a few kilometers apart, and that both ruptured the west-dipping Central Range Fault (CRF). To investigate their rupture behavior and interaction, we performed a joint inversion of teleseismic, strong-motion, and GNSS data. The resulting finite fault models revealed distinct rupture characteristics, with the Guanshan earthquake mainly rupturing down-dip with minor shallow southward extension, in contrast to the Chishang earthquake, which propagated northward toward the surface and produced two shallow asperities. Combining these models with static Coulomb stress calculations and rupture-velocity analysis indicates that Guanshan may have promoted failure of the Chishang segment through static stress transfer, and that a low-velocity zone and clustered aftershocks between the two hypocenters are consistent with a barrier that limited the northward extent of the Guanshan rupture.

2022年9月17日至18日，关山6.5级地震和奇尚7.0级地震袭击了欧亚板块与菲律宾海板块碰撞边界台湾纵向谷。余震模式表明，这两次地震都发生在24小时内，相距仅几公里，而且都使西倾的中央山脉断层破裂。为了研究它们的破裂行为和相互作用，我们对远震、强震和GNSS数据进行了联合反演。所得有限断层模型显示出明显的断裂特征，关山地震以下倾破裂为主，并有少量浅层向南伸展，而赤上地震则向北向地表传播，并产生两个浅层隆起。将这些模型与静态库仑应力计算和破裂速度分析相结合，表明关山可能通过静态应力传递促进了赤上段的破坏，两个震源之间的低速带和聚集性余震与限制了关山向北破裂范围的屏障相一致。

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引用次数: 0

Lithofacies of late cretaceous phosphorite-bearing limestones in the southeastern Turan Block, Afghanistan: implications for paleoenvironmental evolution of the Neo-Tethys 阿富汗图兰地块东南部晚白垩世含磷灰岩岩相：对新特提斯期古环境演化的启示

IF 2.4 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Asian Earth Sciences

Pub Date : 2025-12-23 DOI: 10.1016/j.jseaes.2025.106931

Attiqullah Ayaz , Shuang Shi , Zhenbing She , Tianyang Li , Congliang Liu , Hongjian Zhang , Mohamad Ehsan Omaid , Aftab Ur Rahman , Wei Wang , Kangjun Huang

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., Bulimina aspera) adapted to suboxic bottom waters, contrasting with planktonic foraminifera (Globigerinelloides volutus, Whiteinella archaeocretacea) thriving in productive surface waters. The dominance of the opportunistic species Heterohelix moremani 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.

晚白垩世Sabzak磷矿组代表了阿富汗地层记录中一个独特的含磷酸盐序列，保存了阿富汗-塔吉克盆地北部新特提斯海洋演化的重要古环境档案。本研究对晚白垩世35米厚的碳酸盐序列和沉积在Cenomanian-Turonian边界（~ 94 Ma）周围的1米厚的磷-海绿石组合进行了岩石学和微相分析，并与全球海洋缺氧事件2 （OAE-2）进行了时间相关性分析。不同岩性的微相分析提供了白垩纪新特提斯的古环境和海平面波动的见解。厚的化石鲕粒相、化石灰岩和磷灰岩层显示了从阿尔比世到早Turonian的一套相关环境。这一趋势被标志着晚Turonian期回归的独特的富硅质相打断，随后是标志着重新海侵的苔藓虫和富珊瑚相，在三东统达到顶峰。Sabzak磷矿床可能是在缺氧条件下形成的，同时存在磷矿化、特殊的化石保存、有机质聚集和广泛的海绿石化。底栖有孔虫（如Bulimina aspera）适应于缺氧的底水，与浮游有孔虫（Globigerinelloides volutus， Whiteinella archaeo白垩纪）在多产的表层水中繁茂生长形成对比，进一步表明了分层水柱。机会主义物种异螺旋莫雷马尼的优势强调了对极端条件的适应。总的来说，我们的观察提供了详细的岩石学和古生物学证据，将磷化作用与OAE-2氧化还原分层联系起来，并阐明了新特提斯同期的海平面动力学。

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引用次数: 0