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Crustal structure and seismogenic environment of the Eastern Sichuan Fold-Thrust Belt in South China: Insights from a dense magnetotelluric array 华南川东褶皱冲断带地壳结构与孕震环境：来自密集大地电磁阵的启示

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-10-30 DOI: 10.1016/j.tecto.2025.230973

Sheng Zhang , Nian Yu , Xin Li , Wenxin Kong , Zikun Zhou , Tianyang Li

The present-day tectonic deformation in the Eastern Sichuan Fold-Thrust (ESFTB) far away from plate boundaries is relatively weak, but several moderate to strong earthquakes have occurred in this region during the past decades. To investigate the deep structure and seismogenic environment of this area, a dense broadband magnetotelluric (MT) array were deployed to obtain a three-dimensional (3-D) image of the crustal electrical conductivity structure across the ESFTB. Our resistivity model reveals significant differences in both the depth extent and magnitude of the low-resistivity anomalies in the upper-middle crust on either side of the Qiyao-Jinfoshan Fault (QY-JFF), which has been considered as the boundary between thin-skinned and thick-skinned tectonics. Beneath the QY-JFF, a notable high-resistivity body is imaged and likely reflects the cooled basaltic intrusions associated with the Permain Emeishan volcanism. Given the tectonic context, we prefer to interpret the low-resistivity anomalies as aqueous fluids mainly generated by metamorphic dehydration of the fluid-rich detachment layers, and attribute the differences on either side of the QY-JFF to differing degrees of compressive folding occurred during the early Mesozoic. Most earthquakes along the Fangdoushan Fault (FDSF) are concentrated in a relatively low resistive region that is sandwiched between conductive zones of fluid-rich rock, implying that deep fluid migration into the upper crust may have contributed to triggering earthquakes in this area. Taking into account that these earthquakes are in close proximity to the Yangtze River, the downward infiltration of surface water could also be a potential source of fluids and act as a triggering mechanism for earthquakes.

远离板块边界的川东褶皱逆冲构造现今的构造变形相对较弱，但在过去的几十年中，该地区发生了几次中强地震。为了研究该地区深部构造和孕震环境，利用密集宽带大地电磁阵列（MT），获得了横贯ESFTB的地壳电导率结构三维图像。我们的电阻率模型显示，在被认为是薄皮构造和厚皮构造分界线的祁窑-金佛山断裂（QY-JFF）两侧上-中地壳的低电阻率异常在深度、程度和幅度上都存在显著差异。在QY-JFF下，一个显著的高电阻率体被成像，可能反映了与峨眉山二叠纪火山活动相关的冷却玄武岩侵入体。考虑到构造背景，我们倾向于将低电阻率异常解释为主要由富流体滑脱层变质脱水产生的含水流体，并将QY-JFF两侧的差异归因于早中生代不同程度的压缩褶皱。方斗山断裂沿线的地震多集中在一个相对低阻的区域，该区域夹在富流体岩石导电带之间，表明深部流体向上地壳的运移可能是引发该地区地震的原因之一。考虑到这些地震靠近长江，地表水的向下渗透也可能是流体的潜在来源，并作为地震的触发机制。

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引用次数: 0

Electrical structure of the Muji Basin and adjacent areas in the Pamir: Implications for the 2016 Aketao Mw 6.6 earthquake and the Muji travertine cone group 帕米尔无印品盆地及邻近地区的电性结构：对2016年阿克陶6.6级地震和无印品石灰华锥群的影响

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-05 DOI: 10.1016/j.tecto.2025.230989

Menglong Liao , Yuanzhi Cheng , Bo Han , Zhongxing Wang , Yinan Tian , Yanlong Kong

To reveal the seismogenic mechanism of the 2016 Aketao Mw6.6 earthquake and the formation mechanism of the Muji travertine cone group, this study deployed 56 magnetotelluric (MT) stations in the source region and surrounding the Muji Basin. Post-earthquake magnetotelluric data inversion results demonstrate that: (1) the earthquake hypocenter is located near the interface between low-resistivity body C1 and high-resistivity body R2, representing a finite rupture within high-resistivity body R2; (2) the deep-seated stable fluid system C8 influenced the occurrence of this earthquake, while the genesis and temporal evolution of low-resistivity body C1 remain uncertain; (3) a large-scale low-resistivity body C2 exists north of the Muji travertine cone group. Combined with regional structural analysis, we conclude that the seismogenic process of the 2016 Aketao earthquake was primarily controlled by the coupling between the regional tectonic stress field and local rock mass mechanical properties. The heterogeneity of both stress field and electrical structure along the Muji fault jointly controlled the complex rupture propagation process. Low-resistivity body C2 represents deep fluid presence, where the southwestern boundary fault of the Muji Basin provides migration pathways for deep fluids, thereby controlling the formation and distribution of the travertine cone group.

为揭示2016年阿克陶Mw6.6级地震的发震机制和无印良品钙华锥群的形成机制，在震源区及无印良品盆地周边部署了56个大地电磁测量站。地震后大地电磁资料反演结果表明：(1)震源位于低阻体C1与高阻体R2交界面附近，表现为高阻体R2内的有限破裂；(2)深部稳定流体体系C8影响了本次地震的发生，而低阻体C1的成因和时间演化仍不确定；(3)无印良市石灰华锥群北部存在大型低阻体C2。结合区域构造分析，认为2016年阿克陶地震发震过程主要受区域构造应力场与局部岩体力学特性耦合控制。无印良品断裂应力场和电性结构的非均质性共同控制了复杂的破裂传播过程。低阻体C2代表深部流体存在，无印良河盆地西南边界断裂为深部流体提供了运移通道，从而控制了石灰华锥群的形成和分布。

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引用次数: 0

3D magnetotelluric imaging of lithospheric magmatic systems in the Yitong Volcanic Area, Northeast China: Implications for fault-zone segmentation and seismic rupture dynamics along the Yilan-Yitong Fault 东北伊通火山区岩石圈岩浆系统三维大地电磁成像：宜兰-伊通断裂断裂带分割和地震破裂动力学意义

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-12 DOI: 10.1016/j.tecto.2025.231002

Cong Cao , Lingqiang Zhao , Yan Zhan , Yanfu Qi , Xiangyu Sun , Xiong Yang , Hongbin Lv , Qingliang Wang , Bowen Hou , Wenwen Qi

The Yitong Volcanic Area (YVA) in Jilin Province is a relatively rare “compression type” volcanic system worldwide. Its formation mechanism and eruption mode have unique features. The Yilan-Yitong Fault (YYF) runs through this volcanic rock belt and has demonstrated prominent segmented fracture characteristics since the Quaternary Period. The paleoseismic activity of the Yitong Fault Zone (YFZ) is different from that of other fault zones within this area. This study aimed to investigate the deep magma system in the YVA and its influence on the segmented activities of YYF. Magnetotelluric (MT) measurements were performed in the YVA. A total of 87 MT sites were arranged in the area. A high-resolution three-dimensional (3D) electrical structure model of the lithospheric scale from the crust to the upper mantle in the study area was established with the 3D inversion method. This model suggests that the shallow section of the upper crust of the YVA and the northwestern part of the Songliao Basin were mainly low-resistivity zones, which corresponded to the widely distributed sedimentary layers in this area. The middle and lower crust in the study area was primarily a complete high-resistivity body. A large-scale magmatic system began to appear at a depth of 25 km in the YVA. This magmatic system continued to extend downward, exceeding 70 km. The magma chamber in the YVA was in contact with the YYF in the lower crust. The YYF was the dominant material surging upward through the magma channel. Additionally, deep magmatic activities exerted a crucial influence on the seismic rupture segmentation characteristics along the YYF and the uplift mechanism of the Yitong Basin. The results of this study provide crucial geophysical constraints for depicting the fine depth structure of the YVA while enlightening the investigation of the rupture propagation mechanism within the volcanic terrain fault zone.

吉林省伊通火山区是世界上较为罕见的“压缩型”火山体系。其形成机制和喷发方式具有独特的特点。宜兰-伊通断裂穿过该火山岩带，第四纪以来表现出明显的分段断裂特征。伊通断裂带（YFZ）的古地震活动与该区其他断裂带不同。本研究旨在探讨YVA深部岩浆系统及其对YYF分段活动的影响。大地电磁（MT）测量在YVA进行。该地区共设置了87个MT站点。利用三维反演方法，建立了研究区从地壳到上地幔的岩石圈尺度的高分辨率三维电性结构模型。该模型表明，YVA上地壳浅部和松辽盆地西北部以低电阻率带为主，对应了该地区沉积层的广泛分布。研究区中下地壳主要为完整的高阻体。在YVA的25公里深处开始出现大规模的岩浆系统。这个岩浆系统继续向下延伸，超过70公里。YVA的岩浆房与下地壳的YYF有接触。YYF是通过岩浆通道向上涌动的主要物质。此外，深部岩浆活动对沿YYF的地震破裂分段特征和伊通盆地的隆升机制也有重要影响。本研究结果为描绘YVA的精细深度结构提供了重要的地球物理约束条件，同时也为火山地形断裂带内破裂传播机制的研究提供了启示。

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引用次数: 0

Velocity structure of the 2025 Mw7.7 Myanmar earthquake source region: Insights from traveltime reciprocity tomography 2025年缅甸Mw7.7震源区的速度结构：来自旅行时互反断层成像的见解

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-04 DOI: 10.1016/j.tecto.2025.230985

Fengxue Zhang , Yu Li , Yiping Chen

This study explores the velocity structure of the 2025 Mw7.7 Myanmar earthquake source region using seismic wave traveltime reciprocity tomography, a method that leverages the reciprocal relationship between sources and receivers to address the challenge of sparse station coverage. This inversion resolves robust velocity anomalies and remains generally stable with respect to the changes in the spatial extent of the study area. Tomographic results reveal a prominent north-south low-velocity zone that extends along the north-south trending Sagaing Fault, highlighting its role as the primary rupture zone. To the east of the fault, a broad high-velocity anomaly likely marks the steeply eastward-subducting Indian Plate beneath the Shan Plateau, whereas to the west, a localized high-velocity feature is consistent with a near-horizontal slab morphology beneath the Myanmar Central Basin. These findings provide new constraints on the deep structure and geodynamic processes beneath Myanmar.

本研究利用地震波走时互易层析成像技术（一种利用震源和接收机之间的互易关系来解决稀疏台站覆盖挑战的方法）探索了2025年缅甸Mw7.7震源区的速度结构。这种反演解决了强大的速度异常，并且相对于研究区域空间范围的变化保持了总体稳定。层析成像结果显示，沿南北走向的实皆断裂延伸出明显的南北低速带，突出了其作为主破裂带的作用。在断层东部，广泛的高速异常可能标志着掸邦高原下急剧向东俯冲的印度板块，而在断层西部，局部的高速特征与缅甸中央盆地下的近水平板块形态相一致。这些发现为缅甸深部构造和地球动力学过程提供了新的约束条件。

引用次数: 0

Late Cretaceous intracontinental subduction along the Bangong-Nujiang Suture Zone: evidence from the K-rich magmatism in the Lunpola Basin, central Tibetan Plateau

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-10-31 DOI: 10.1016/j.tecto.2025.230975

Ping Wang , Haijian Lu , Liang Duan , Xuxuan Ma , Yihu Zhang , Wang Li

The Late Cretaceous magmatic rocks, widely distributed along the Bangong-Nujiang Suture Zone (BNSZ), not only records large-scale crust-mantle interactions, but also contains characteristic fingerprints of deep geodynamic processes. However, the formation regime is still controversial, with proposed mechanisms including lithospheric delamination, the rollback of the Neo-Tethys Ocean, and the subduction of the Bangong-Nujiang Ocean. To address this issue, we conducted zircon UPb dating, in situ Hf isotope analysis, and whole-rock major and trace element compositions on the Late Cretaceous volcanic rocks in the Lunpola Basin, central Tibet. Geochronological results indicate that they crystallized primarily at ∼80 Ma, which was followed by a ∼ 65 Ma pulse. These volcanic rocks exhibit high-K compositions (K₂O/Na₂O = 1.8–55.8), marked by enrichment in Rb, Th, Pb, and light rare earth elements (LREEs), coupled with depletion in Nb, Ta, and Ti—a geochemical signature diagnostic for subduction-related magmatism. The broad range of zircon ε_Hf(t) values (−15.49 to +15.51) provides robust evidence for contributions from Qiangtang ancient continent crust to the formation of the (ultra) potassic rocks. Given the widespread distribution of coeval (∼80 Ma) magmatic rocks along the BNSZ and geophysical data, we propose that the petrogenesis of the Late Cretaceous potassic rocks originated from southward subduction of the Qiangtang terrane beneath the Lhasa terrane. This study not only proposes a new tectonic model for the nature of the Lhasa-Qiangtang collision but also highlights the vital role of intracontinental subduction in producing post-collisional potassic-ultrapotassic magmatism.

广泛分布于班公-怒江缝合带（BNSZ）的晚白垩世岩浆岩不仅记录了大规模的壳幔相互作用，而且具有深部地球动力学过程的特征指纹。然而，其形成机制仍存在争议，提出的机制包括岩石圈拆沉、新特提斯洋的回滚和班公-怒江洋的俯冲。地质年代学结果表明，它们主要在~ 80 Ma时结晶，随后是~ 65 Ma脉冲。这些火山岩具有高钾组成（K₂O/Na₂O = 1.8 ~ 55.8）， Rb、Th、Pb和轻稀土元素（lree）富集，Nb、Ta和ti富集，这是俯冲相关岩浆活动的地球化学特征诊断。锆石εHf(t)值范围（- 15.49 ~ +15.51）较宽，为羌塘古陆壳对（超）钾质岩的形成提供了有力证据。考虑到BNSZ沿线同时期（~ 80 Ma）岩浆岩的广泛分布和地球物理资料，我们认为晚白垩世钾质岩石的成因可能源于拉萨地体之下羌塘地体的向南俯冲。该研究不仅为拉萨-羌塘碰撞的性质提出了新的构造模式，而且强调了陆内俯冲在碰撞后钾-超古典岩浆活动的产生中所起的重要作用。

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引用次数: 0

Mantle transition zone dynamics beneath the Northwestern Deccan Volcanic Province, India: Implications for plume mediated upper mantle processes 印度西北德干火山省地幔过渡带动力学：对地幔柱介导的上地幔过程的启示

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-12 DOI: 10.1016/j.tecto.2025.231000

Rema Vaishali , Madhusudhanarao Katlamudi , Ayoub Kaviani , Georg Rümpker

The Deccan Volcanic Province (DVP), formed ∼65 Ma during India's northward drift and linked to the Réunion plume, reveals complex upper-mantle structures. This study uses P receiver function (RF) analysis from 76 broadband stations in Gujarat, Western India, to image upper-mantle discontinuities (d410 and d660) beneath the north-western DVP. RF depth migration was performed using 1-D and 3-D tomographic velocity models—GYPSUM, LLNL-G3Dv3, MEAN2, and a combined regional model (up to 300 km depth) incorporating LLNL-G3Dv3. The estimated mantle transition zone (MTZ) thickness varies from 233 to 248 km in Kachchh, Saurashtra, Cambay, South Gujarat, and the Arabian Sea, while in North Gujarat and the Narmada rift zones; it ranges from 251 to 255 km. The d410 discontinuity exhibits a uniform depression (410–430 km), whereas the d660 remains normal to slightly deepened (650–675 km). The eastern North Gujarat, Narmada zone, and parts of Kachchh exhibit a shallow 410 km and depressed 660 km discontinuity, indicating MTZ thickening. The Cambay thermal anomaly, bounded by these colder regions, likely reflects localized small-scale upwelling coupled with the downwelling of ancient subducted slab remnants. Additionally, 520 km discontinuity was detected, with amplitude peaks suggesting a low-velocity layer above d410. The Mean excess temperatures associated with d410 and d660depressions are ∼150 K and ∼ 323 K, respectively. MTZ structure, thermal anomalies, and mantle velocity heterogeneities collectively indicate plume–lithosphere interaction influenced by relic slab dynamics in the genesis of Deccan volcanism.

德干火山省（DVP）形成于印度向北漂移期间的~ 65 Ma，与r地幔柱有关，显示出复杂的上地幔结构。本研究使用来自印度西部古吉拉特邦76个宽带站的P接收函数（RF）分析，对西北DVP下的上地幔不连续体（d410和d660）进行成像。RF深度偏移使用1-D和3-D层析速度模型（石膏、LLNL-G3Dv3、MEAN2）以及包含LLNL-G3Dv3的组合区域模型（深度达300 km）进行。在Kachchh， Saurashtra, Cambay， South Gujarat和Arabian Sea，而在North Gujarat和Narmada裂谷带，估计的地幔过渡带（MTZ）厚度在233 ~ 248 km之间；它的范围从251到255公里。d410不连续面呈均匀凹陷（410 ~ 430 km），而d660不连续面保持正常或略深（650 ~ 675 km）。北古吉拉特邦东部、Narmada地区和Kachchh部分地区表现出410 km的浅层不连续和660 km的凹陷不连续，表明MTZ增厚。坎贝热异常以这些较冷的区域为界，可能反映了局部的小规模上升流和古代俯冲板块残余物的下升流。此外，探测到520 km的不连续层，振幅峰值表明在d410上方存在低速层。与d410和d660凹陷相关的平均过量温度分别为~ 150 K和~ 323 K。MTZ结构、热异常和地幔速度非均质性共同表明了德干火山成因中受遗迹板块动力学影响的柱-岩石圈相互作用。

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引用次数: 0

Revealing deep-rooted pre-Paleozoic fault systems in the lower Yangtze region: Insights from 3D magnetic inversion and gravity inversion and integrated geophysical interpretation 揭示下扬子地区前古生代深层断裂体系：三维磁重反演与综合地球物理解释的启示

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-12 DOI: 10.1016/j.tecto.2025.231001

Chongjin Zhao, Luolei Zhang, Huang Zuwei, Peng Yu

The Lower Yangtze region lies between the North China Craton and Cathaysia Block; yet, the offshore continuity of major sutures and the role of inherited basement faults remain debated. We integrate 3-D inversions of regional magnetic and gravity data for crustal framework imaging without reduction-to-the-pole. In particular, we perform magnetic inversion directly on the total magnetic intensity (TMI) under oblique field geometry, coupled with a sharp-boundary gravity inversion to the TMI-derived magnetic basement. Petrophysical ranges for densities and susceptibilities provide the sole priors, and edges are mapped with a tilt–hyperbolic–vertical–horizontal (THVH) operator. Misfits reach observational noise levels, and the recovered volumes resolve long- to intermediate-wavelength structures. Magnetization is concentrated beneath the East China Sea shelf and southern South Yellow Sea, while 10–20 km density slices delineate alternating uplift–depression couplets. Three surfaces (i.e., the Magnetic-basement top, Paleozoic-basement proxy depth, and Proterozoic residual-thickness proxy) define coherent gradients that, together with THVH ridges, map a consistent fault framework. We infer (i) an eastward offshore continuation of the Jiangshan–Shaoxing Fault that bends northeast and is truncated near the southwestern margin of Jeju Island; (ii) a lithosphere-scale Yangtze–North China boundary coincident with the Korea–West Fault; and (iii) four inherited NE–EW faults that segment the region into alternating uplifts and depressions. The architecture supports Late Cretaceous back-arc extension and selective reactivation of Precambrian discontinuities.

下扬子地区位于华北克拉通与华夏地块之间；然而，主要缝合线的海上连续性和继承的基底断层的作用仍然存在争议。我们整合了区域磁场和重力数据的三维反演，用于地壳框架成像，而无需还原到极点。特别是，我们直接对斜场几何形状下的总磁强度（TMI）进行了磁反演，并对TMI导出的磁基底进行了锐边界重力反演。岩石物理范围的密度和敏感性提供了唯一的先验，边缘是用倾斜-双曲-垂直-水平（THVH）算子绘制的。失配达到观测噪声水平，恢复的体积分解出长至中波长结构。磁化集中在东海陆架和南黄海南部，而10-20公里的密度片描绘了交替的升降对联。三个面（即磁基底顶部、古生代基底代理深度和元古代残余厚度代理）定义了相干梯度，并与THVH脊一起绘制了一致的断层格架。我们推断(1)江山-绍兴断裂向东延伸，向东北弯曲，在济州岛西南边缘附近被截断；（ii）与韩-西断裂重合的岩石圈尺度的扬子-华北边界；(3) 4条继承的NE-EW断裂，将该地区划分为隆升和坳陷交替。该构造支持晚白垩世弧后伸展和前寒武纪不连续性的选择性恢复。

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引用次数: 0

Crustal structure of the Fiji-Lau Basin-Tonga-Samoa region from receiver functions 从接收函数看斐济-劳盆地-汤加-萨摩亚地区的地壳结构

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-02 DOI: 10.1016/j.tecto.2025.230977

Ying Zhang , Hao Hu , Walter D. Mooney

The Fiji-Lau Basin-Tonga-Samoa region, situated at a complex tectonic junction involving subduction, back-arc spreading, and mantle plume activity, provides a natural laboratory for investigating crustal growth processes at convergent margins, and enhances regional seismic hazards assessments. We present estimates of crustal thickness variations and Vp/Vs ratios derived from P-wave receiver functions and H-κ stacking across 46 broadband seismic stations from multiple networks. Our results reveal a mean crustal thickness of ∼17.8 km and an average Vp/Vs ratio of 1.84, consistent with an intermediate to mafic crustal composition. Crustal thickness varies significantly across the region, with the thickest crust (∼30 km) beneath northern Fiji, a remnant island arc formed during Eocene-Miocene subduction. In comparison, the thinnest (∼6 km) is observed in the actively spreading Lau Basin. Intermediate thicknesses (19–25 km) are observed along the Lau and Tonga Ridges. In the Samoa Islands, crustal thickness increases eastward from 16 km to 25 km, paired with declining Vp/Vs ratios (1.9 to 1.6), suggesting a compositional transition from subduction-related magmatism to more differentiated felsic intraplate magmatism associated with the Samoan hotspot. Although the thinner crust across the island arc systems lacks sufficient volume to form continental crust without post-accretionary thickening, the presence of thicker crust (23–30 km) beneath parts of the region may represent incipient juvenile continental crustal formation.

斐济-劳盆地-汤加-萨摩亚地区位于一个涉及俯冲、弧后扩张和地幔柱活动的复杂构造交界处，为研究汇聚边缘的地壳生长过程提供了一个天然实验室，并加强了区域地震危险性评估。我们提出了来自多个网络的46个宽带地震台站的p波接收函数和H-κ叠加的地壳厚度变化和Vp/Vs比值的估计。我们的结果显示，地壳平均厚度为~ 17.8 km，平均Vp/Vs比值为1.84，与中基性地壳组成一致。整个地区的地壳厚度差异很大，最厚的地壳（约30公里）位于斐济北部，这是始新世-中新世俯冲期间形成的残余岛弧。相比之下，在活跃扩张的劳盆地观测到最薄（~ 6 km）。沿劳脊和汤加脊可观测到中等厚度（19-25公里）。在萨摩亚群岛，地壳厚度从16 km向东增加至25 km， Vp/Vs比值下降（1.9 ~ 1.6），表明萨摩亚群岛地壳成分由俯冲相关岩浆活动向与萨摩亚热点相关的更分化的长英质板内岩浆活动转变。虽然横跨岛弧系统的较薄地壳没有足够的体积形成大陆地壳而没有后增生增厚，但该地区部分地区较厚地壳（23-30公里）的存在可能代表了早期的幼年大陆地壳形成。

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引用次数: 0

Strain energy-driven grain growth in quartz aggregates: Implications for microstructural evolution and recovery 应变能驱动的石英团聚体晶粒生长：微观结构演化和恢复的意义

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-10-27 DOI: 10.1016/j.tecto.2025.230971

Petar Pongrac , Malte Ortmanns , Petr Jeřábek , Sebastian Cionoiu , Jean Furstoss , Yuval Boneh , Lucie Tajčmanová

Grain growth in quartz aggregates is traditionally understood as a surface energy driven process, where larger grains grow at the expense of smaller ones in order to reduce the total grain surface area. However, most studies that contributed to this concept used relatively homogeneous, fine-grained quartz aggregates, which may not precisely reflect natural samples. Here, we performed an isotropic hot-pressing experiment using a coarser-grained quartz powder with grain sizes between 64 and 125 μm. The experiment was carried out using a Griggs-type solid-medium apparatus at controlled conditions of 1 GPa, ∼950 °C, and hot-pressing duration of ∼8 h. A thermal gradient across the sample produced progressive microstructural variations, reflecting differing intensities of recovery overprint interpreted as distinct evolutionary stages. EBSD analysis revealed that relatively smaller grains with low internal misorientation (i.e., low dislocation density), grew at the expense of both smaller and larger grains with higher misorientation (i.e., higher dislocation density). Grain boundary density remained constant throughout the microstructural evolution, suggesting that the stored strain energy of the system was reduced without reducing surface energy. Interestingly, the strain energy driving force was sufficient to mobilize—and ultimately eliminate—typically more stable low-angle boundaries between growing and consumed small grains. These findings challenge the conventional grain growth models, demonstrating that local strain energy differences can dominate microstructural evolution under static conditions, overriding surface energy as the primary driving force. This has implications for interpreting annealed quartz microstructures in natural rocks and raises caution for direct use of recrystallized grain size as a paleo-stress proxy in rocks that underwent static recovery after deformation.

石英团聚体中的晶粒生长传统上被理解为表面能驱动的过程，其中较大的晶粒生长以牺牲较小的晶粒为代价，以减少总晶粒表面积。然而，促成这一概念的大多数研究都使用了相对均匀、细粒的石英聚集体，这可能无法准确反映自然样品。本文采用粒径在64 ~ 125 μm之间的粗晶石英粉末进行了各向同性热压实验。实验使用griggs型固体介质装置，控制条件为1 GPa， ~ 950°C，热压时间为~ 8小时。样品的热梯度产生渐进的微观结构变化，反映了不同强度的恢复套印被解释为不同的进化阶段。EBSD分析显示，相对较小的内部取向错误（即低位错密度）晶粒的生长是以较小和较大的内部取向错误（即高位错密度）晶粒的生长为代价的。晶界密度在微观组织演变过程中保持不变，表明体系的存储应变能在不降低表面能的情况下降低。有趣的是，应变能驱动力足以动员——并最终消除——生长和消耗小颗粒之间通常更稳定的低角度边界。这些发现挑战了传统的晶粒生长模型，表明在静态条件下，局部应变能差异可以主导微观结构的演化，而不是表面能作为主要驱动力。这对解释天然岩石中的退火石英微观结构具有重要意义，并对直接使用再结晶粒度作为变形后静态恢复岩石的古应力代理提出了警告。

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引用次数: 0

Precise relocation of the 14 August 2021 Mw 7.2 Nippes, Haiti, earthquake sequence using broadband and citizen-hosted short-period seismometers 使用宽带和公民托管的短周期地震仪精确定位2021年8月14日海地Nippes的Mw 7.2地震序列

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-10 Epub Date: 2025-11-12 DOI: 10.1016/j.tecto.2025.230982

Sylvert Paul , Tony Monfret , Eric Calais , Françoise Courboulex , Bertrand Delouis , Anthony Lomax , Bernard M. de Lépinay , Steeve J. Symithe , Anne Deschamps , David Ambrois , Sadrac St Fleur , Dominique Boisson

On 14 August 2021, the Southern Peninsula of Haiti experienced a M

_{w}

7.2 earthquake, 15 years after the devastating M

_{w}

7.0 event that struck the capital city of Port-au-Prince on 12 January 2010. We use the data from a local temporary broadband seismic network, a national network of low-cost seismometers, and regional seismic networks, together with a probabilistic, global-search, non-linear location method (NLL-SSST-coherence), to obtain a catalog of 5341 precisely relocated events spanning 20 August 2021 to 6 February 2022, with local magnitudes ranging from 0.5 to 5.6. We compute focal mechanisms for a subset of 73 events through waveform inversion. The catalog can be split into aftershocks directly related to the Nippes earthquake rupture process, and two off-rupture clusters. A first one concerns the Anse-à-Veau–Miragoâne area and corresponds mostly to the aftershock sequence of two M

_{w}

5.3 and 4.9 earthquakes that likely activated a segment of the offshore, south-dipping, Jérémie–Malpasse reverse fault system. A second sequence, offshore Jérémie and clustered close to the offshore trace of that same fault, started immediately after the Nippes mainshock and continued during the entire time interval of the present study. The swarm–like temporal distribution of this sequence, as well as evidence for directional propagation of the epicenters, indicate that it was likely driven by fluid migration. We interpret this seismicity as the result of oblique sub-crustal slip on a south-dipping fault which accounts for oblique convergence between the Gonâve and Caribbean plates in southern Hispaniola. Strain in the crust then partitions between reverse faulting on the Jérémie–Malpasse fault system, strike-slip on the Enriquillo fault, and hybrid faulting in between. Seismic hazard assessment for the region should therefore account for faults other than the Enriquillo fault as potential sources for future earthquakes.

2021年8月14日，海地南部半岛发生里氏7.2级地震，距2010年1月12日首都太子港发生里氏7.0级地震已有15年。我们使用来自当地临时宽带地震台网、国家低成本地震仪台网和区域地震台网的数据，以及概率、全局搜索、非线性定位方法（nl - ssst相干性），获得了5341个精确定位的事件目录，时间横跨2021年8月20日至2022年2月6日，当地震级范围为0.5至5.6。我们通过波形反演计算了73个事件子集的震源机制。该目录可分为与尼普斯地震破裂过程直接相关的余震和两个非破裂集群。第一个地震与Anse -à-Veau-Miragoâne地区有关，主要与两次5.3和4.9级地震的余震序列相对应，这些地震可能激活了离岸、向南倾斜的jsamrsammie - malpasse逆断层系统的一部分。第二个序列，离岸的jsamrsammie，聚集在同一断层的离岸痕迹附近，在尼普斯主震之后立即开始，并在本研究的整个时间间隔中继续进行。该序列的群状时间分布以及震中定向传播的证据表明，它可能是由流体运移驱动的。我们将这种地震活动性解释为南倾断层上斜向地壳下滑动的结果，该断层解释了伊斯帕尼奥拉岛南部gon和加勒比板块之间的斜向辐合。然后，地壳中的应变被划分为jsamrsammi - malpasse断层系统的逆断层、Enriquillo断层的走滑断层和介于两者之间的混合断层。因此，该地区的地震危险性评估应考虑到除Enriquillo断层以外的其他断层是未来地震的潜在震源。

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