Tectonophysics最新文献_第3页

Multiscale fault complexity and hydrothermal processes drive earthquake swarms in the Tengchong Volcanic Field, Southeastern Tibetan Plateau 青藏高原东南部腾冲火山田多尺度断裂复杂性和热液作用驱动地震群

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-14 DOI: 10.1016/j.tecto.2026.231080

Jin-Zhi Ma , Lingsen Meng , Hao Yin , Yiming Bai , Zekun Li , Yinshuang Ai

Situated in the southeastern Tibetan Plateau, the Tengchong volcanic region is characterized by elevated surface heat flow and serves as a natural laboratory for investigating fluid-induced seismicity within structurally complex fault systems. Using a dense 12-month broadband seismic dataset, we construct a high-resolution earthquake catalog and identify three distinct seismic swarms. These swarms extend beyond classical stepovers, involving diverse fault structures such as conjugate systems and sharply curved fault bends. All occur along pre-existing faults, with two located to the east and southeast of the main Tengchong volcanic zone, in previously unstudied areas. This indicates that both the spatial distribution and evolution of swarm activity are strongly influenced by fault geometry. The swarms' spatiotemporal behavior is well described by a pore-pressure diffusion process, as evidenced by distinct migration fronts and back fronts, and correlated fluctuations in background seismicity rates. Notably, the swarms exhibit localized stress heterogeneity, likely driven by variations in excess pore-fluid pressure. In Swarm 3, a three-phase migration pattern and rupture orientations nearly perpendicular to the main fault trace further suggest that fault geometry and local stress heterogeneity play a dominant role in rupture behavior. Additionally, the lower b-values observed in Swarm 3 imply higher differential stress and a greater potential for moderate-to-large earthquakes. These observations indicate that swarm evolution in the Tengchong region is governed by a combination of pore-pressure diffusion, inherited fault structures, and stress field heterogeneity. Both the diffusion and the heterogeneous stress conditions are likely linked to elevated excess pore-fluid pressure.

腾冲火山区位于青藏高原东南部，具有地表热流升高的特点，是研究构造复杂断裂系统中流体诱发地震活动性的天然实验室。利用密集的12个月宽带地震数据集，我们构建了一个高分辨率的地震目录，并确定了三个不同的地震群。这些群超出了经典的阶梯，涉及不同的断层结构，如共轭系统和急剧弯曲的断层弯曲。所有这些都发生在先前存在的断层上，其中两个位于腾冲主要火山带的东部和东南部，在以前未研究的地区。这表明，群活动的空间分布和演化都受到断层几何形状的强烈影响。孔隙压力扩散过程很好地描述了蝗群的时空行为，这可以通过明显的迁移前沿和后前沿以及背景地震活动率的相关波动来证明。值得注意的是，蜂群表现出局部应力不均匀性，可能是由孔隙流体压力变化引起的。在Swarm 3中，三相运移模式和几乎垂直于主断层的破裂方向进一步表明，断层几何形状和局部应力非均质性在破裂行为中起主导作用。此外，在Swarm 3观测到的较低的b值意味着较高的差应力和更大的中到大地震的可能性。这些结果表明，腾冲地区的群演化是由孔隙压力扩散、继承断裂构造和应力场非均质性共同控制的。扩散和非均质应力条件都可能与孔隙流体压力升高有关。

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引用次数: 0

Active backthrusting in the hanging wall of the Chelungpu Fault: Structural insights from surface deformation analysis 车隆堡断裂上盘活动逆冲：地表变形分析对构造的启示

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-14 DOI: 10.1016/j.tecto.2026.231082

Yi-Chun Hsu , Chung-Pai Chang , Jiun-Yee Yen , Chun-Chin Wang , Chih-Heng Lu , Nai-Wun Shih , Shao-Yi Huang , Yu-Ting Kuo , I-Chin Yen

Taiwan lies within an active fold-and-thrust belt along the boundary between the Eurasian Plate and the Philippine Sea Plate, where arc-continent collision drives intense crustal deformation and frequent seismicity. The 1999 Mw 7.6 Chi-Chi earthquake, caused by rupture of the Chelungpu Fault in central Taiwan, brought significant attention to the structural evolution of its hanging wall. To investigate interseismic deformation in this region, we apply Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) to Sentinel-1 imagery from 2018 to 2021. While the main Chelungpu Fault trace remains locked, PSInSAR data reveal localized uplift and eastward motion along the Hsinshe Lineament and Ailiao Fault. Integrating geodetic velocities, topographic features, field observations, and elastic dislocation modeling, we interpret these structures as active backthrusts associated with variations in the Chelungpu ramp geometry. These findings refine previous interpretations of fault-bend folding and demonstrate that stress transfer from the locked frontal thrust may reactivate secondary structures in the hanging wall. This study highlights the role of backthrust faulting in strain accommodation and illustrates the utility of PSInSAR in resolving subtle interseismic processes within complex thrust systems.

台湾位于欧亚板块与菲律宾海板块交界的活跃褶皱冲断带内，弧陆碰撞导致地壳剧烈变形，地震活动频繁。1999年发生在台湾中部的车隆铺断裂带断裂引起的7.6 Mw集集地震，引起了人们对其上盘构造演化的高度关注。为了研究该地区的震间形变，我们将持续散射干涉合成孔径雷达（PSInSAR）应用于2018年至2021年的Sentinel-1图像。在车隆堡主断裂带闭锁的情况下，PSInSAR数据显示了沿新社线和艾寮断裂带的局部隆升和东移。综合大地测量速度、地形特征、野外观测和弹性位错建模，我们将这些结构解释为与车隆堡斜坡几何形状变化相关的活跃逆冲构造。这些发现完善了先前对断层弯曲褶皱的解释，并表明来自封闭的前缘冲断的应力传递可能重新激活上盘的次级构造。这项研究强调了逆冲断层在应变调节中的作用，并说明了PSInSAR在解决复杂逆冲系统中微妙的震间过程中的实用性。

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引用次数: 0

Holocene surface-rupturing earthquakes on the Matano fault in the Mahalona basin, Sulawesi, Indonesia 印度尼西亚苏拉威西岛马哈洛纳盆地马塔诺断裂带全新世地表破裂地震

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-12 DOI: 10.1016/j.tecto.2026.231084

Adi Patria , Muhammad Hanif , Anggraini Rizkita Puji

The Matano fault in Sulawesi, Indonesia, accommodates the left-lateral motion between the Pacific and Australian plates, and it poses a high seismic hazard. We investigated past surface-rupturing earthquakes on the Ponsoa segment of the Matano fault in the Mahalona basin through an integration of tectonic geomorphic observation, ground-penetrating radar (GPR) survey, and paleoseismic investigation. Adjacent to the paleoseismic trench site, the Ponsoa segment is characterized by a ∼0.5–2-m-high north-facing fault scarp on a young fluvial terrace. The GPR profile acquired crossing the fault scarp shows the associated subsurface structures to a depth of ∼10 m. The trench revealed evidence of two surface-faulting events with timing constrained at 891–1113 CE and 1035–1425 CE. Correlating these findings with paleoseismic events on the Geresa segment suggests a multi-segment earthquake rupture scenario involving the eastern half of the Matano fault (∼145 km long) with a probable magnitude (Mw) of ∼7.6 and a recurrence interval of ∼294–444 years. This study highlights the significance of paleoseismic investigations for seismic hazard assessment, particularly in establishing the rupture extent and recurrence interval of large surface-rupturing earthquakes.

印度尼西亚苏拉威西岛的马塔诺断层容纳了太平洋板块和澳大利亚板块之间的左侧运动，它具有很高的地震危险性。通过构造地貌观测、探地雷达（GPR）测量和古地震调查相结合的方法，对Mahalona盆地Matano断裂Ponsoa段的地表破裂地震进行了研究。Ponsoa段毗邻古地震沟遗址，其特征是在年轻的河流阶地上形成一条 ~ 0.5 ~ 2 m高的北向断崖。穿过断崖的探地雷达剖面显示了~10 m深度的相关地下构造。海沟显示了两个地表断裂事件的证据，时间限制在891-1113 CE和1035-1425 CE。将这些发现与Geresa段的古地震事件相结合，表明在Matano断层东半部（~145 km长）发生了多段地震破裂，可能震级（Mw）为~7.6，复发间隔为~ 294-444 年。本研究强调了古地震调查对地震危险性评价的重要意义，特别是在确定地表大破裂地震的破裂程度和复发间隔方面。

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引用次数: 0

Formation of sedimentary and tectonic mélanges during seamount subduction: new insights from analog modeling 海山俯冲过程中沉积和构造障碍的形成：模拟模拟的新见解

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-12 DOI: 10.1016/j.tecto.2026.231085

Tatiana Tkáčiková, Jiří Žák

This study presents three sets of scaled ‘sandbox’ experiments designed to understand the formation of mélanges during seamount subduction, focusing, in particular, on the role of talus aprons and moat basins, i.e., loose block accumulations around seamounts formed on the seafloor prior to subduction. In the first set of experiments, subduction of a single seamount increases wedge taper, inducing slumping of previously accreted material and producing sedimentary mélanges. Increasing the slab dip enhances off-scraping of material from the seamount's leading side, deposition on the rear side, and apron incorporation into the wedge interior. The second set simulates the subduction of a seamount chain, leading to wedge thickening, increased mass wasting, and the formation of a layered mélange-bearing unit between the seamounts. The third set simulates oceanic plateau-wedge interactions, resulting in increased mass wasting on the wedge's surface and the formation of sedimentary mélanges. Loose blocks are deposited along the plateau surface and incorporated into the wedge along shear zones, creating tectonic mélanges. In conclusion, our results indicate that sedimentary and tectonic mélanges form during seamount subduction, especially from the surrounding talus. Sedimentary mélanges are deposited at the wedge surface through sliding and mixing of blocks with a terrigenous matrix, while the tectonic mélanges result from intense shear deformation along the seamount/wedge interface. When compared with seismic profiles across modern accretionary wedges, our findings also suggest that the often-observed chaotic reflections may represent previously unrecognized seamount-derived mélanges, however, their type is difficult to establish just from geophysical data.

本研究提出了三组规模的“沙盒”实验，旨在了解海山俯冲期间msamulanges的形成，特别关注距石围和护城河盆地的作用，即在俯冲之前在海底形成的海山周围的松散块体堆积。在第一组实验中，单个海山的俯冲增加了楔形锥度，引起先前堆积的物质的塌降，并产生沉积变径。增加板倾角可以增强海山前缘材料的刮离、后侧的沉积以及裙板与楔体内部的结合。第二组模拟了海山链的俯冲，导致楔形增厚，增加质量浪费，并在海山之间形成层状单元。第三组模拟了海洋高原-楔体的相互作用，导致楔体表面的质量浪费增加，并形成了沉积模体。松散的块体沿高原表面沉积，并沿剪切带并入楔形，形成构造障碍。综上所述，沉积和构造障碍是在海山俯冲过程中形成的，特别是在海山周围的距坡上。沉积型岩石是通过块体与陆源基质的滑动和混合作用在楔体表面沉积的，而构造型岩石则是由楔体内部沿海山/楔体界面强烈的剪切变形形成的。当与现代增生楔的地震剖面进行比较时，我们的研究结果还表明，经常观察到的混沌反射可能代表以前未被识别的海山衍生的海变岩，然而，仅从地球物理数据很难确定它们的类型。

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引用次数: 0

Late quaternary eruption history of the Tatun Volcano Group (Taiwan) – new constraints from zircon double-dating and 40Ar/39Ar dating of lava flows in Mt. Shamao 台湾大屯火山群晚第四纪喷发史——沙茅山熔岩流锆石双定年和40Ar/39Ar定年的新约束

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-11 DOI: 10.1016/j.tecto.2026.231083

Karl D. Jabagat , Yuan-Hsi Lee , Martin Danišík , Daniel Miggins , Mei-Fei Chu , Yu-Ming Lai , Yun-Chieh Lo , Po-Tsun Lee , Cheng-Horng Lin

Growing evidence for an active magmatic system beneath the Tatun Volcano Group (TVG) in northern Taiwan has heightened efforts to understand its eruption history. Accurately constraining the timing of past eruptions is essential for evaluating volcanic hazards, particularly given the TVG's proximity to the densely populated Taipei metropolitan area. However, previous studies have yielded inconsistent results, underscoring the need for robust and reliable geochronological methods. This study aims to constrain the age and eruption history of the Shamao lava dome, which is considered the youngest eruptive product in the TVG, by applying a zircon double-dating approach that combines UTh disequilibrium and (UTh)/He methods, alongside high-precision ⁴⁰Ar/³⁹Ar groundmass dating. Zircon UTh disequilibrium data constrain the maximum eruption age of Mt. Shamao to 16.3 ± 1.2 ka and reveal both protracted crystallization of zircon spanning ca. 200 ka and distinct age clusters at ca. 23, 60, and 117 ka, with some grains in secular equilibrium (>300 ka). These older populations coincide with other magmatic events in the TVG, suggesting zircon inheritance or the tapping of a long-lived, interconnected magma reservoir with episodic pulses. Zircon (UTh)/He dating yields a late Pleistocene eruption age of 16.3 ± 4.9 ka, consistent with a new groundmass ⁴⁰Ar/³⁹Ar plateau age of 15.0 ± 6.3 ka and previously reported radiocarbon ages indicating eruptive activity between ca. 23 and 13 ka. These results challenge earlier interpretations of Holocene volcanism in Mt. Shamao (i.e. at 1.3 ka) and highlight the reliability of integrated geochronological techniques for dating young volcanic rocks. While additional data are required to refine eruption recurrence models, this study provides a critical foundation for improving volcanic hazard assessments and risk mitigation strategies in northern Taiwan.

越来越多的证据表明，台湾北部的大屯火山群（TVG）下存在活跃的岩浆系统，这加大了人们对其喷发历史的了解。准确限制过去火山爆发的时间对于评估火山危害至关重要，特别是考虑到TVG靠近人口稠密的台北大都市区。然而，先前的研究得出了不一致的结果，强调了对稳健可靠的地质年代学方法的需求。本文采用锆石双测年法，结合UTh不平衡法和(UTh)/He法，结合高精度40Ar/39Ar地质体测年，对被认为是TVG中最年轻的喷发产物——沙茅熔岩穹丘的年龄和喷发历史进行了研究。锆石UTh不平衡资料约束了沙茅山最大喷发年龄为16.3 ± 1.2 ka，显示了200 ka左右的锆石长时间结晶，以及23、60和117 ka左右的不同年龄群，部分颗粒处于长期平衡（>300 ka）。这些年龄更大的人群与TVG中的其他岩浆事件相吻合，表明锆石遗传或者是一个长期存在的、相互联系的岩浆储层的突发性脉冲的开采。锆石(UTh)/He定年结果表明，晚更新世喷发年龄为16.3 ± 4.9 ka，与新地块40Ar/39Ar高原年龄15.0 ± 6.3 ka和先前报道的放射性碳年龄一致，表明喷发活动在约23 ~ 13 ka之间。这些结果挑战了早先对沙毛山（即1.3 ka）全新世火山活动的解释，并强调了综合地质年代学技术对年轻火山岩定年的可靠性。本研究为改善台湾北部火山灾害评估及风险缓释策略提供了重要的基础。

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引用次数: 0

Structural analysis and low-temperature thermochronology of the Ozbak-Kuh Mountains, Central Iran: Constraints on the influence of intraplate strike-slip faulting in the Arabia–Eurasia collision zone 伊朗中部Ozbak-Kuh山脉的构造分析和低温热年代学：对阿拉伯-欧亚碰撞带板内走滑断裂影响的约束

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-08 DOI: 10.1016/j.tecto.2026.231079

Ali Ghiassi , Ali Yassaghi , Massimiliano Zattin , Saeed Madanipour , Reza Nozaem

Intracontinental deformation in collision zones is generally localized along basement strike-slip fault zones, resulting in crustal shortening and fault-related exhumation of rocks. Strike-slip faulting plays a key role in accommodating crustal deformation in Central Iran, which is located within the active collision zone between the Arabian and Eurasian plates. This study investigates the impact of basement strike-slip faulting on intracontinental deformation of the Central Iran Microcontinent. These deformations are extensively localized in the Kashmar–Kerman Tectonic Zone (KKTZ). Previous U-Pb radiometric dating and thermochronometric studies from the southern parts of the zone have recorded predominantly Early Mesozoic events, whereas the northern parts document Cenozoic events. However, the central part of the zone, in the Ozbak-Kuh Mountains, has remained poorly constrained. Integration of new structural data with low-temperature thermochronometric data from the Ozbak-Kuh Mountains reveals two distinct cooling events. The first event, dated to the Late Cretaceous–Paleocene (∼55–75 Ma), coincided either with the initial closure of the Neo-Tethys Ocean and obduction of its ophiolites, or with the closure of a back-arc basin located to the north. In either scenario, the driving mechanism reflects a convergent tectonic setting characterized by folding of Paleozoic–Mesozoic rocks and deposition of the unconformable Paleocene Kerman Conglomerate. The second cooling event, which occurred during the late Eocene–Oligocene (∼27–37 Ma), is interpreted to mark the onset of continental–continental collision between the Arabian and Eurasian plates, as evidenced by the development of an angular unconformity between Oligocene–Miocene strata and older rock units. This event also led to transpressional deformation along the Kalmard Fault Zone (KFZ). Accelerated cooling in the western parts of the Ozbak-Kuh Mountains, as indicated by apatite fission-track (AFT) data, highlights the significant role of strike-slip faulting in accommodating oblique convergence.

碰撞带的陆内变形一般沿基底走滑断裂带定位，导致地壳缩短和与断层相关的岩石掘出。伊朗中部位于阿拉伯板块和欧亚板块的活动碰撞带内，走滑断裂在调节地壳变形中起着关键作用。本文研究了基底走滑断裂对伊朗中部微大陆陆内变形的影响。这些变形广泛局限于喀什马尔-克尔曼构造带。以前的U-Pb放射性测年和热年代学研究主要记录了早中生代事件，而北部记录了新生代事件。但是，安全区的中心部分，在奥兹巴克-库赫山脉，仍然受到很差的限制。将新的构造数据与来自Ozbak-Kuh山脉的低温热时学数据相结合，揭示了两个不同的冷却事件。第一个事件发生在晚白垩世-古新世（~ 55-75 Ma），与新特提斯洋的初始闭合和蛇绿岩的逆冲相吻合，或者与位于北部的弧后盆地的闭合相吻合。在这两种情况下，驱动机制反映了以古生代-中生代岩石褶皱和不整合的古新世Kerman砾岩沉积为特征的会聚构造环境。第二次冷却事件发生在晚始新世-渐新世（~ 27-37 Ma），这标志着阿拉伯板块和欧亚板块之间大陆碰撞的开始，渐新世-中新世地层与更古老的岩石单元之间形成了角度不整合。这一事件还导致了沿卡尔玛德断裂带（KFZ）的挤压变形。磷灰石裂变径迹（AFT）数据表明，Ozbak-Kuh山脉西部加速冷却，突出了走滑断层在适应斜向辐合中的重要作用。

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引用次数: 0

Seismic source parameters analysis in Southeastern Alps and associated tectonic implications 阿尔卑斯东南部震源参数分析及其构造意义

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-06 DOI: 10.1016/j.tecto.2026.231069

L. Moratto, F. Abdi, A. Saraò

We present a comprehensive analysis of earthquake source parameters in the Southeastern Alps, a tectonically complex region located at the junction of the Eastern Alps and the Dinarides. Using single station spectral inversion of S-wave displacement spectra from 1521 well-recorded earthquakes (1.3 ≤ M_W ≤ 4.3) occurring between 2016 and 2023, we estimated seismic moment, corner frequency, static stress drop, apparent stress, radiated energy, and seismic efficiency. Our results reveal a small deviation from self-similar scaling condition, with static stress drop values ranging mostly from 0.1 to 10 MPa (median ≈ 0.84 MPa) and apparent stress stabilizing above 1 MPa for moderate events. The Savage-Wood efficiency values suggest a dominant overshoot rupture regime, indicating that only a fraction of the available stress is radiated as seismic energy. The spatial patterns of stress drop and attenuation correlate with the underlying tectonic domains. Regions characterized by strong, competent crust exhibit higher stress drops and lower attenuation, whereas areas with fractured, fluid-rich fault zones show lower stress drops and stronger attenuation. This study highlights the value of high-resolution spectral analysis and dense seismic networks for characterizing rupture processes and provides a new regional reference dataset for ground motion prediction and seismic hazard assessment in Southeastern Alps and comparable intraplate environments.

本文对位于东阿尔卑斯山脉和迪纳里德斯山脉交界处的构造复杂的东南阿尔卑斯地区的震源参数进行了综合分析。利用2016 - 2023年间1521次地震（1.3≤MW≤4.3）的s波位移谱单站反演，估算了地震弯矩、角频率、静应力降、表观应力、辐射能和地震效率。结果表明，该方法与自相似结垢条件偏差较小，静应力降值范围主要在0.1 ~ 10 MPa之间（中位数≈0.84 MPa），中等强度事件的视应力稳定在1 MPa以上。Savage-Wood效率值表明了一个主要的超冲破裂状态，表明只有一小部分可用应力作为地震能量辐射。应力下降和衰减的空间分布规律与下伏构造域有关。强韧地壳区域的应力降较大，衰减较小，而断裂、富流体断裂带区域的应力降较小，衰减较强。该研究强调了高分辨率光谱分析和密集地震台网在表征破裂过程中的价值，并为阿尔卑斯东南部和类似板内环境的地震动预测和地震危险性评估提供了新的区域参考数据集。

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引用次数: 0

Tectonics of East Indian Subcontinent: As derived from Integrated Gravity Anomalies of India, Bangladesh, Bay of Bengal and Myanmar Regions 东印度次大陆的构造：来自印度、孟加拉国、孟加拉湾和缅甸地区的综合重力异常

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-06 DOI: 10.1016/j.tecto.2025.231061

J.V. Rama Rao , Ravi Kumar Bandi , T.R.K. Chetty

The East Indian Subcontinent (EISC) is a geologically complex region recording tectonic evolution from the Proterozoic era to the present. This study integrates terrestrial, marine, and satellite gravity data across ∼5 million sq. km covering eastern India, Bangladesh, the Bay of Bengal, and Myanmar, along with earthquake incidences from the past 120 years to unravel the tectonic framework of the region.

A Key focus of this study is building the interrelations among major Proterozoic orogenic belts—Central Indian Tectonic Zone (CITZ), Eastern Ghats Mobile Belt (EGMB), Chhotanagpur Granite Gneissic Complex (CGGC), and Shillong Meghalaya Gneissic Complex (SMGC). From this study, we propose a possible eastern boundary of the CITZ marked as Lucknow–Varanasi–Ranchi lineament, highlight the remarkable affinities between eastern CGGC and EGMB, and redefine the Eastern Continental Margin of India.

Gravity analysis delineates the disposition of collision zones of EISC besides inferring five tectonic domains of EISC, crustal boundaries, plate margins, and transitions from continental to oceanic crust. It also reveals heterogeneity over submarine ridges and the segmentation of the India–Myanmar subduction zone. Aseismic central segment, bounded by cross-faults, is an explicit inference of our study about current Indo-Australian plate subduction dynamics beneath the Sunda–Myanmar Plate.

东印度次大陆（EISC）是一个地质复杂的地区，记录了从元古代到现在的构造演化。这项研究整合了约500万平方英尺的陆地、海洋和卫星重力数据。覆盖了印度东部、孟加拉国、孟加拉湾和缅甸，以及过去120年的地震事件，从而揭开了该地区的构造框架。建立元古代主要造山带—印度中部构造带（CITZ）、东高止山脉活动带（EGMB）、Chhotanagpur花岗片麻岩杂岩（CGGC）和西隆-梅加拉亚片麻岩杂岩（SMGC）之间的相互关系是本研究的重点。在此基础上，我们提出了Lucknow-Varanasi-Ranchi界线作为CITZ可能的东部边界，强调了CGGC东部与EGMB之间的显著亲和性，并重新定义了印度东部大陆边缘。重力分析除了推断出东陆板块碰撞带的5个构造域、地壳边界、板块边缘和陆壳向洋壳过渡外，还圈定了东陆板块碰撞带的配置。它还揭示了海底脊的非均质性和印缅俯冲带的分段性。以交叉断裂为界的地震中心段是我们对巽他-缅甸板块下现今印澳板块俯冲动力学研究的明确推论。

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引用次数: 0

Polyphasic deformation during the evolution of the southern Central Andes: Insights from the La Ramada fold-thrust belt (32°-32°30′S) 中安第斯山脉南部演化过程中的多相变形：来自La Ramada褶皱冲断带（32°-32°30’s）的启示

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-06 DOI: 10.1016/j.tecto.2026.231070

Nicolás Alejandro Peluffo , Lucas Martín Fennell , Sarah Ellen Thomas , Federico Exequiel Martos , Victor Valencia , Andrés Folguera , Maximiliano Naipauer

This work presents an update of the evolution of the La Ramada fold-thrust belt (∼32°S-32°30′S), located in a remote area of the Principal Cordillera of Argentina, integrating two measured stratigraphic sections, novel field observations, and three new zircon UPb ages: two detrital and one igneous. Our new stratigraphic framework includes Paleocene to Miocene sedimentary and volcanic rocks, a period previously interpreted as a hiatus in the area. This sheds light on an enigmatic stage in the evolution of the Andes at these latitudes. We describe the Teatinos Formation, a sedimentary unit with a maximum depositional age of 11.2 ± 0.2 Ma at its base. These rocks were deposited in the Teatinos Basin, a newly defined piggyback basin developed within the Principal Cordillera, representing the innermost expression of the Miocene Andean foreland basin system at these latitudes. A new UPb crystallization age of 19.1 ± 0.5 Ma, obtained from a sill intruding ∼900 m of volcanic rocks, confirms the presence of the late Eocene - early Miocene Abanico Formation in an anomalous position, up to 5 km east of the eastern boundary of the Abanico Basin. This boundary is represented in our area by the Major Andean Fault, a first-order structure that juxtaposes rocks of the western Principal Cordillera over the Teatinos Formation. We also present a new maximum depositional age of 145.2 ± 1.5 Ma from sedimentary rocks in the hanging wall of this fault. These are overlain by the Abanico Formation, defining a > 100 Myr hiatus compatible with the existence of a pre-Oligocene contractional event. We propose a polyphasic evolution for the La Ramada fold-thrust belt involving at least three contractional pulses: one pre-Oligocene and two during the Miocene (ca. 22–18 Ma and ca. 12–9 Ma).

本文对位于阿根廷Principal Cordillera偏远地区的La Ramada褶皱冲断带（~32°S-32°30’s）的演化进行了更新，整合了两个测量的地层剖面、新的野外观测和三个新的锆石UPb年龄：两个碎屑和一个火成岩。我们的新地层格架包括古新世到中新世的沉积岩和火山岩，这一时期以前被解释为该地区的裂谷期。这揭示了安第斯山脉在这些纬度的演化过程中的一个神秘阶段。我们描述了Teatinos组，这是一个沉积单元，其底部的最大沉积年龄为11.2 ± 0.2 Ma。这些岩石沉积在Teatinos盆地中，Teatinos盆地是在Principal Cordillera内发育的一个新定义的背驮式盆地，代表了中新世安第斯前陆盆地体系在这些纬度的最内部表达。新的UPb结晶年龄为19.1 ± 0.5 Ma，来自仍侵入~900 m的火山岩，证实了晚始新世-早中新世Abanico组在Abanico盆地东部边界以东5 km的异常位置存在。这个边界在我们的地区由安第斯大断层代表，这是一个一级结构，将西部主要科迪勒拉的岩石与Teatinos组并列。在断层上盘沉积岩中发现了新的最大沉积年龄145.2 ± 1.5 Ma。它们被Abanico组覆盖，定义了一个 >； 100迈的裂谷，与前渐新世收缩事件的存在相一致。我们提出La Ramada褶皱冲断带的多相演化包括至少三个收缩脉冲：一个前渐新世和两个中新世（约22-18 Ma和约12-9 Ma）。

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引用次数: 0

Reevaluation of geomorphic offsets along the 1920 Haiyuan earthquake rupture, China: A discussion of uncertainties in slip measurements and COPD analyses using high-resolution topography 1920年中国海原地震断裂带沿线地貌偏移的再评价：高分辨率地形对滑动测量和COPD分析不确定性的讨论

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2026-01-05 DOI: 10.1016/j.tecto.2026.231071

Longfei Han , Wenqian Yao , Jing Liu-Zeng , Yann Klinger , Chengguo Yan , Peng Wang , Yanxiu Shao

Accurate measurements of coseismic slip distributions derived from geomorphic markers provide essential insights into earthquake rupture dynamics and make a significant contribution to seismic hazard evaluation. With the increased availability of high-resolution topographic data and advanced statistical techniques such as cumulative offset probability distribution (COPD), reconstructing single-event coseismic displacement from cumulative offsets of successive paleoearthquakes has become more feasible. However, assessing the reliability of these methods remains critical. The 1920 Mw7.9 Haiyuan earthquake, the most recent major event along the strike-slip Haiyuan fault, serves as an ideal case study due to notable discrepancies in previously reported displacement measurements. In this study, we utilize very high-resolution (0.1 m) topographic data derived from aerial imagery processed via the Structure from Motion (SfM) technique, covering approximately 85 km of the ∼240 km rupture length. Our analysis, based on detailed horizontal slip measurements and COPD calculation, yields a maximum displacement of 7.6 ± 0.8 m for the 1920 Haiyuan earthquake, differing from previous estimates but aligning well with global scaling relationships for strike-slip earthquakes. Our results reveal three COPD peaks in the geomorphic records along the Haiyuan fault. The displacement interval between the two most recent peaks is similar to that of the latest peak, with reduced displacement observed in the western section. These findings suggest that previous interpretations of four to five events may significantly overestimate single-event slip. Comparisons with previous studies underscore the methodological challenges in COPD-based reconstructions, including uncertainties from different slip measurement methods, geomorphic marker interpretations, fault geometry, along-strike slip variability, and the contribution of moderate-magnitude earthquakes to cumulative offsets.

从地貌标志中得到的同震滑动分布的精确测量为地震破裂动力学提供了重要的见解，并对地震危险性评估做出了重大贡献。随着高分辨率地形数据的可用性和累积偏移概率分布（COPD）等先进统计技术的增加，利用连续古地震的累积偏移重建单事件同震位移变得更加可行。然而，评估这些方法的可靠性仍然至关重要。1920年海原Mw7.9地震是海原走滑断层最近的一次重大地震，由于以前报道的位移测量值存在显著差异，因此可以作为一个理想的研究案例。在这项研究中，我们使用了非常高分辨率（0.1 m）的地形数据，这些数据来自通过运动构造（SfM）技术处理的航空图像，覆盖了约240公里断裂长度中的85公里。我们的分析基于详细的水平滑动测量和COPD计算，得出1920年海原地震的最大位移为7.6±0.8 m，与之前的估计不同，但与走滑地震的全球尺度关系很好地吻合。结果表明，在海原断裂沿线的地貌记录中存在3个慢阻肺峰值。两个最近的峰值之间的位移间隔与最近的峰值相似，但在西段观测到的位移较小。这些发现表明，以前对四到五个事件的解释可能大大高估了单事件滑动。与以往研究的对比强调了基于copd的重建在方法上的挑战，包括不同滑动测量方法的不确定性、地貌标志解释、断层几何形状、沿走滑变异性以及中震级地震对累积偏移量的贡献。

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引用次数: 0