Tectonophysics最新文献_第5页

Updated map and insights into emplacement conditions of Ighrem doleritic dyke (Anti-Atlas Mountains, Morocco) 摩洛哥反阿特拉斯山脉（Anti-Atlas Mountains, Morocco） Ighrem白云岩岩脉的更新地图及就位条件研究

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-26 DOI: 10.1016/j.tecto.2025.231060

Mustapha Bouiflane , Ahmed Manar

Two long NE-trending doleritic dykes are found cropping out in the Anti-Atlas Mountains. The the Foum Zguid dyke has generated wide interest in geological research because considered as one of the best-preserved products of the Central Atlantic Magmatic Province. However, the Ighrem dyke remains relatively less explored owing to the paucity of unaltered rock exposures. In this contribution, we investigate the Igherm dyke from analysis and interpretation of new high-resolution aeromagnetic data to follow its trace and prolongation over large areas lacking surface exposure. Geological interpretation results highlight the geophysical signature of the Igherm dyke which allowed us to propose an updated map of the dyke. This map shows the dyke prolongation farther to the northeast as well as towards the southwest spreading over 270 km. Moreover, the Igherm dyke appears to be fragmented into multiple segments with varying morphology most of them do not reach the surface and reveals a number of different segmentation structures in many locations of the relays between adjacent segments. According to the magmatic and tectonic settings of the Anti-Atlas, we consider that the emplacement of the Ighrem dyke is mainly driven by structural control of pre-existing fractures. However, we assume that additional factors, such as regional structural patterns, change in both the local and the regional stress fields, magma flow conditions and host rock heterogeneities may play roles in whether the intrusion of the dyke reach the surface or be arrested at various crustal levels but also controlling the geometrical form of the dyke.

在反阿特拉斯山脉中发现了两条北东向的长白云岩岩脉。富姆兹圭德岩脉是中大西洋岩浆省保存最完好的产物之一，引起了地质研究的广泛兴趣。然而，由于缺乏未改变的岩石暴露，对Ighrem堤防的探索相对较少。在这篇论文中，我们通过分析和解释新的高分辨率航磁数据来研究Igherm岩脉，以跟踪其在缺乏地表暴露的大面积上的轨迹和延伸。地质解释结果突出了Igherm堤防的地球物理特征，使我们能够提出更新的堤防图。这张地图显示了堤坝向东北和西南延伸了270多公里。此外，Igherm岩脉似乎被破碎成多个具有不同形态的分段，其中大多数没有到达表面，并且在相邻分段之间的继电器的许多位置显示出许多不同的分段结构。根据反阿特拉斯地区的岩浆和构造环境，我们认为Ighrem岩脉的侵位主要是由构造控制的。然而，我们认为区域构造模式、局部和区域应力场的变化、岩浆流动条件和寄主岩石的非均质性等其他因素可能对岩脉的侵入是否到达地表或在不同的地壳水平上被阻止起作用，但也控制着岩脉的几何形状。

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引用次数: 0

Gravity-derived crustal thickness heterogeneity in the Philippine Archipelago: Implications for a new microplate framework 菲律宾群岛重力衍生的地壳厚度非均质性：一个新的微板块框架的含义

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-26 DOI: 10.1016/j.tecto.2025.231059

Liang Jin , Jie Liu , Sanzhong Li , Yanhui Suo , Pengcheng Wang , Junjiang Zhu

Located in the collision zone between the Eurasian and Philippine Sea plates, the Philippine Mobile Belt (PMB), with intense earthquakes and volcanism, is a typical area for the study of plate subduction, island arc accretion, and microplate amalgamation. However, due to the complexity of tectonic history of this region, the existing studies are still deficient in understanding the crustal structure and deep dynamics. To address this, we develop a new improved crustal thickness model for the Philippine Archipelago using EIGEN-6C4 gravity data and advanced inversion methodology. Integration of microplate boundary kinematics and active fault systems permits division of the PMB into nine discrete microplates. Our study shows that pronounced isostatic disequilibrium along the Manila Trench, Philippine Trench, and Philippine Fault, indicating active lithospheric adjustment. The crustal thickness of the PMB shows significant spatial heterogeneity, revealing the existence of anomalous crustal thickening spatially correlated with volcanic chains flanking the main Philippine Fault Zone. We propose a dual-mechanism crustal thickening model driven by both multi-stage accretionary processes and deep magma underplating, offering new insights into the crust-mantle interactions governing the Philippine orogenic system and microplate geodynamics.

菲律宾活动带（PMB）位于欧亚海板块与菲律宾海板块碰撞带，地震和火山活动强烈，是研究板块俯冲、岛弧增生和微板块合并的典型区域。然而，由于该区构造历史的复杂性，现有研究在对地壳结构和深部动力学的认识上仍存在不足。为了解决这一问题，我们利用EIGEN-6C4重力数据和先进的反演方法，建立了一个新的改进的菲律宾群岛地壳厚度模型。微板块边界运动学和活动断层系统的整合允许将PMB划分为九个离散的微板块。研究表明，沿马尼拉海沟、菲律宾海沟和菲律宾断裂带存在明显的均衡不平衡，表明岩石圈调整活跃。PMB地壳厚度表现出明显的空间异质性，表明存在与菲律宾主断裂带两侧火山链相关的异常地壳增厚。我们提出了一个由多阶段增生过程和深部岩浆下垫共同驱动的双机制地壳增厚模型，为菲律宾造山系统的壳幔相互作用和微板块地球动力学提供了新的见解。

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引用次数: 0

Deep electrical structure and thermodynamic mechanism of the high-temperature geothermal field in Kangding, Western Sichuan, China 川西康定高温地热田深部电性结构及热力机制

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-24 DOI: 10.1016/j.tecto.2025.231055

Gang Zhang , Yongjie Tang , Xuben Wang , Yu Ma , Yushu Tang , Chao Zhang

The Kangding geothermal field in western China, despite abundant high-temperature resources, has low utilization (<8 %) due to unclear deep genesis models. This study used magnetotelluric (MT) data from 30 stations along a 140 km profile, combined with 3D inversion, to build a deep electrical conductivity model. By integrating electrical conductivity-temperature relationships and heat conduction equations, it further developed thermal structure and rock partial melting models. The study also analyzed crustal heat flow, Moho depth, and tectonic dynamics to explore deep thermo-tectonic mechanisms. Key findings include: (1) A “high-low-high” crustal electrical structure with low-resistivity zones (20–50 km depth) indicating eastward crustal flow; (2) High temperatures (>850 °C), water content (1–7 wt%), and partial melting (1–10 %, up to >10 % in core areas) as major heat sources; (3) The Xianshuihe Fault as a deep-seated fracture enabling strike-slip heat generation and fluid transfer; (4) A geothermal system integrating mid-lower crustal heat, fault friction, and precipitation recharge. These insights enhance understanding of Kangding's geothermal activity, supporting improved resource assessment. Acknowledging parameter limitations, this study adopted a geophysically validated conductivity-temperature method, which may cause minor model-prediction discrepancies compared to actual conditions.

中国西部康定地热田虽然高温资源丰富，但深层成因模式不明确，利用率低（约8%）。本研究利用140公里剖面上30个测点的大地电磁数据，结合三维反演，建立了深部电导率模型。通过整合电导率-温度关系和热传导方程，进一步建立了热结构和岩石部分熔融模型。研究还分析了地壳热流、莫霍深度和构造动力学，探讨了深部热构造机制。主要发现包括：(1)“高-低-高”的地壳电性结构，其低电阻率带（深度20 ~ 50 km）指示地壳东向流动；(2)高温（>850°C）、含水量（1 - 7wt %）和部分熔融（1 - 10%，核心区域高达>； 10%）为主要热源；(3)鲜水河断裂是一条深部断裂，有利于走滑产热和流体传递；(4)中下地壳热、断层摩擦和降水补给相结合的地热系统。这些发现增强了对康定地热活动的认识，有助于改进资源评价。考虑到参数的局限性，本研究采用了经地球物理验证的电导率-温度方法，与实际情况相比，这可能会导致模型预测存在较小的差异。

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引用次数: 0

The emplacement of an intraplate volcanic system in the Xiangshan Basin, Southeast China, implied from resistivity constrained 3D gravity and magnetic joint inversion 基于电阻率约束的三维重磁联合反演揭示了东南象山盆地板内火山体系的侵位

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-22 DOI: 10.1016/j.tecto.2025.231054

Min Feng , Juzhi Deng , Hui Yu , Hui Chen , Yunong Wei , Yanguo Wang , Xiao Chen

The intraplate volcanic system in Xiangshan basin provides the main source of ore-forming materials for the world's third-largest volcanogenic uranium deposit. Although geological evidence suggests the existence of two volcanic cycles, the geometries of complete volcanic systems remain enigmatic and are not fully understood, as are the underlying emplacements responsible, due in part to the lack of sufficient geophysical data. To refine the structure of the volcanic system, we applied a gravity-magnetic joint inversion constrained by the resistivity model. The results delineated the first volcanic cycle rhyodacite conduit beneath the Shutang area in the western basin, characterized by high susceptibility and dipping southwest in the shallow subsurface, with its emplacement controlled by a low-density east–west-trending basement fault activated by regional north-south extension stresses. The second volcanic cycle porphyroclastic lava conduit, characterized by low density and high susceptibility, dips southeastward and extends toward the northeast flank of Mount Xiangshan. In the west, the high susceptibility of the first-cycle volcanic conduit suggests that the second-cycle porphyroclastic lava conduit may have inherited the earlier magmatic pathway, with its emplacement jointly controlled by low-density regional north–south basement faults activated by east–west extension stresses and pre-existing east–west structures. These results underscore the dominant role of regional tectonic environments in controlling the multi volcanic cycles and provide new insight for emplacement mechanisms in a strike-slip extension environment.

象山盆地的板内火山体系为世界第三大火山型铀矿床提供了主要的成矿物质来源。虽然地质证据表明存在两个火山旋回，但完整的火山系统的几何形状仍然是谜，并没有完全理解，由于缺乏足够的地球物理数据，潜在的火山位也是如此。为了细化火山体系的构造，我们应用了电阻率模型约束下的重磁联合反演。圈定了盆地西部树塘地区首条火山旋回流纹石导管，具有高易感性、浅层向西南倾斜的特征，侵位受区域南北伸展应力激活的低密度东西向基底断裂控制。第二火山旋回的斑岩熔岩导管呈东南倾向，向象山东北侧延伸，具有低密度、高易感性的特征。在西部，第一旋回火山导管的高易感性表明第二旋回斑岩熔岩导管可能继承了早期的岩浆通道，其侵位受东西向伸展应力激活的低密度区域性南北基底断裂和已有的东西向构造共同控制。这些结果强调了区域构造环境在控制多火山旋回中的主导作用，并为走滑伸展环境下的侵位机制提供了新的认识。

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引用次数: 0

Crustal structure and tectonic implications of the Southern Central Asian Orogenic Belt: New insights from gravity, magnetic, and magnetotelluric imaging 中亚南部造山带的地壳结构和构造意义：来自重、磁和大地电磁成像的新见解

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-22 DOI: 10.1016/j.tecto.2025.231053

Chutong Chen , Na Li , Lingxiao Zhang , Hongying An , Chang’an Guo , Xing Fu , Songda Lei , Guicai Yang , Junjie Fan , Weiheng Yuan , Hao Wang , Bin Wang , Kunpeng Wang

The Alxa and Beishan domains experienced extensive arc-related magmatism during the closure of the Paleo Asian Ocean, followed by long-lived intracontinental deformation. Widespread sedimentation has obscured their deep structures and mutual relations. Here we integrate gravity, magnetic, and magnetotelluric data to refine the crustal structures and evaluate the tectonic linkage between the Alxa and Beishan domains. Geophysical contrasts across the Quagan Qulu–Tebai suture identify it as a major lithospheric boundary, separating accretionary complexes in the north from continental lithosphere in the south. In southern Alxa, magnetic and gravity anomalies delineate two concealed early Permian arc belts, whose spatial alignment with ductile strike-slip zones suggests their localization along lithospheric weaknesses during post-collisional transpression. Across the Alxa–Beishan boundary, east–west ophiolitic magnetic highs are not directly continuous. Northeast-trending faults, including the Sanweishan and Ruoshui faults, disrupt the boundary, and the gravity field indicates a discontinuous rather than uniform crustal architecture. These geophysical observations support the view that a direct connection between the Alxa and Beishan is unlikely. The Sanweishan fault is identified as a crustal-scale structure that, together with the Xingxingxia and Ruoshui faults, forms a major fault system distributed in the Beishan domain. Collectively, these results highlight segmented tectonic domains and largely independent Mesozoic deformation in Alxa and Beishan, offering new geophysical constraints on their crustal architecture and mutual tectonic linkage.

阿拉善和北山域在古亚洲洋闭合期间经历了广泛的弧相关岩浆活动，随后发生了长期的陆内变形。广泛的沉积遮蔽了它们的深层构造和相互关系。本文综合重、磁、大地电磁资料，对阿拉善域和北山域的地壳结构进行了细化，并评价了它们之间的构造联系。夸甘-古鲁-特拜缝合带的地球物理对比表明，它是一个主要的岩石圈边界，将北部的增生杂岩与南部的大陆岩石圈分开。在阿拉善南部，磁重异常圈定了两条隐伏的早二叠世弧形带，其空间走向与韧性走滑带一致，表明其定位于碰撞后变形过程中岩石圈的薄弱部位。在阿拉善-北山边界，东西走向的蛇绿岩磁高不是直接连续的。东北向断裂（包括三微山断裂和若水断裂）破坏了边界，重力场表明地壳结构不是均匀的，而是不连续的。这些地球物理观测支持阿拉善和北山之间不太可能有直接联系的观点。三微山断裂是一个地壳尺度的构造，与星形峡、若水断裂共同构成北山域的主要断裂体系。总的来说，这些结果突出了阿拉善和北山的分段构造域和基本独立的中生代变形，为它们的地壳结构和相互构造联系提供了新的地球物理约束。

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引用次数: 0

Definition of the Andean seismogenic-active front in the Malargüe fold and thrust belt using a local seismic network and gravity data 用局部地震台网和重力资料定义malarg<s:1> e褶皱和冲断带的安第斯造震活动锋

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-22 DOI: 10.1016/j.tecto.2025.231052

Marianela Lupari , Héctor P.A. García , Silvina Nacif , Andrés Folguera , Francisco Ruiz

This study focuses on the central sector of the Malargüe Fold and Thrust Belt (35.5°–36.5°S), where the limited crustal seismicity of the Payenia volcanic field and the presence of Quaternary deposits complicate the delineation of the neotectonic front and the identification of active structures. The deployment of a seismological network enabled the recording of local seismicity, revealing hypocenters clustered into two main groups in the upper crust, associated with NE–SW oriented basement structures. Focal mechanism analysis indicates a predominance of dextral strike-slip faulting with subordinate reverse components, while gravity data link the earthquakes to the source bodies generating the main anomalies. Group A activity reflects deformation accommodated by dextral basement faults modulated by reverse motion, with implications for hydrocarbon migration and accumulation. Group B highlights the interaction between deep structures, upper-crustal anisotropies, and active magmatic processes beneath the Payún Matrú volcano. These findings suggest that both inherited structures and mantle-related thermal anomalies (SWAP) govern stress distribution and seismicity in the region.

本研究以马拉拉 e褶皱冲断带中部（35.5°-36.5°S）为研究对象，该区帕耶尼亚火山场有限的地壳地震活动和第四纪沉积的存在，使得新构造前缘的圈定和活动构造的识别复杂化。地震台网的部署使当地地震活动得以记录，揭示了上地壳中聚集的两个主要震源群，与东北-西南向的基底结构有关。震源机制分析表明，地震以右旋走滑断裂为主，反向分量次之，而重力数据将地震与产生主要异常的震源体联系起来。A组活动反映了受反向运动调节的右旋基底断裂调节的形变，具有油气运移和聚集的意义。B组突出了Payún Matrú火山下深部构造、上地壳各向异性和活跃岩浆过程之间的相互作用。这些发现表明，继承构造和地幔相关热异常（SWAP）共同控制着该地区的应力分布和地震活动。

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引用次数: 0

Imaging the northern Zagros collision zone by ambient noise and earthquake surface wave tomography 利用环境噪声和地震表面波层析成像对扎格罗斯碰撞带北部进行成像

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-19 DOI: 10.1016/j.tecto.2025.231041

Zahra Zarunizadeh , Abdelkrim Aoudia , Khalil Motaghi , Surya Pachhai , Daniel Manu-Marfo , Yingjie Yang , Wathiq Abdulnaby , Yinshuang Ai , Ling Chen

The Zagros collision zone provides a natural laboratory for investigating the early stages of continental collision and mountain building. This study presents Rayleigh wave phase and group velocity tomography for the northern Zagros, using new seismic data from western Iran and eastern Iraq. Ambient noise tomography for both group and phase velocities was conducted over periods of 7–35 s. In addition, earthquake data were used to compute phase velocity tomograms for periods of 29–100 s, employing a two-plane-wave tomography technique. Nonlinear inversion of node-wise dispersion curves from both group and phase velocity dispersion data produced a 3-D shear-wave velocity (Vs) model extending to a depth of 200 km. The Vs model reveals: (1) a mid-crustal low-velocity layer (20–30 km depth) beneath the Zagros suture, extending 100–250 km northward with spatial variability; (2) a high-velocity anomaly (Vs ∼3.6 km/s) at 5–20 km depth beneath the Sanandaj-Sirjan zone, interpreted as the exhumed Zagros crystalline core at the overriding margin of Central Iran; and (3) a high-velocity lithospheric mantle (Vs ∼4.7 km/s) with varying lateral extent and thickness along the orogen. These features point to differing convergence mechanisms, with underthrusting dominating in the northwest and a combination of underthrusting and internal deformation in the southeast. Furthermore, a thinner Arabian lithosphere in the northwestern Zagros, compared to thicker lithosphere elsewhere, suggests ongoing partial delamination in the lower portion of the lithospheric mantle.

扎格罗斯碰撞带为研究大陆碰撞和造山的早期阶段提供了一个天然的实验室。本研究利用伊朗西部和伊拉克东部的新地震数据，对扎格罗斯北部进行了瑞利波相位和群速度层析成像。在7 - 35s的周期内对群速度和相速度进行环境噪声层析成像。此外，采用双平面波层析成像技术，利用地震数据计算29-100秒周期的相速度层析成像。利用群频散和相频散数据对节点方向频散曲线进行非线性反演，得到了延伸至200 km深度的三维横波速度（Vs）模型。v模式显示：(1)在Zagros缝合线下方存在中地壳低速层（深度20 ~ 30 km），向北延伸100 ~ 250 km，具有空间变异性；(2) sanandaji - sirjan带下方5 - 20km深度的高速异常（Vs ~ 3.6 km/s），被解释为伊朗中部上覆边缘挖掘出的Zagros晶体岩心；(3)高速岩石圈地幔（Vs ~ 4.7 km/s）沿造山带横向范围和厚度变化。这些特征表明了不同的辐合机制，西北部以逆冲构造为主，东南部以逆冲构造和内部变形相结合。此外，与其他地方较厚的岩石圈相比，扎格罗斯西北部较薄的阿拉伯岩石圈表明，岩石圈地幔下部正在发生部分分层。

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引用次数: 0

Asperity dynamics and secondary damage development during the closure of a fracture in granite 花岗岩裂缝闭合过程中的粗度动力学和次生损伤发育

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-19 DOI: 10.1016/j.tecto.2025.231044

Jessica McBeck , Benoît Cordonnier , François Renard

The dynamics of asperities and the resulting real contact area play an important role in the evolving frictional strength of fault zones, particularly during the interseismic period. The aperture of fractures controls the ability of fluids to traverse meaningful distances in geologically and industrially relevant timescales. Here, we show the evolution of the real contact area and aperture at increasing normal load in a triaxial compression experiment with X-ray tomography on a Westerly granite rock core with a preexisting core-spanning fracture oriented perpendicular to the maximum compressive principal stress direction, at a confining pressure of 15 MPa and fluid pressure of water of 10 MPa. At the onset of normal loading, the real contact area increases linearly with the differential stress, at a rate of about 0.2 %/MPa until the real contact area is 20 %, mostly though the accumulation of greater numbers of individual contacts, consistent with elastic deformation. Then the real contact area increases more rapidly with load, with increasing areas of individual contacts, consistent with plastic deformation. The real contact area reaches maximum values of 35 %, and then declines with increasing loading as secondary axial fractures propagate from the large sub-horizontal fracture. The average mechanical aperture first declines rapidly with loading, reaches a minimum value of 13 μm, and then increases before failure as secondary axial fractures develop. The rough sub-horizontal fracture and secondary axial fractures produce a long-lived zone of elevated porosity, which is 4 % above the background porosity (1–2 %) just before failure. Thus, a closing rough fracture can provide a conduit for fluid flow due to non-zero aperture and the production of secondary damage.

在断裂带摩擦强度的演化中，特别是在震间期，岩石的动力学和实际接触面积起着重要的作用。裂缝的孔径控制着流体在地质和工业相关时间尺度上穿越有意义距离的能力。在围压为15 MPa、水流体压力为10 MPa的条件下，利用x射线层析成像技术对西风花岗岩岩心进行了三轴压缩实验，研究了岩心在增大法向载荷作用下的实际接触面积和孔径变化规律。在正常加载开始时，实际接触面积随差应力以约0.2% /MPa的速率线性增加，直到实际接触面积达到20%，这主要是通过大量个体接触的积累，与弹性变形一致。实际接触面积随着载荷的增加而迅速增加，单个接触面积的增加与塑性变形一致。实际接触面积达到最大值35%，然后随着加载的增加，次级轴向裂缝从大的亚水平裂缝扩展而减小。随着加载的增加，平均机械孔径先迅速减小，达到最小值13 μm，破坏前随着二次轴向断裂的发展而增大；粗糙的亚水平裂缝和次级轴向裂缝产生了一个长寿命的高孔隙度区，在破坏前比背景孔隙度（1 - 2%）高4%。因此，由于非零孔径和二次损伤的产生，闭合粗裂缝可以为流体流动提供通道。

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引用次数: 0

Insights into the 2021 Arkalochori (Crete Island, southern Greece) foreshock swarm through an enhanced deep-learning seismic catalog 通过增强的深度学习地震目录，深入了解2021年Arkalochori（希腊南部克里特岛）前震群

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-19 DOI: 10.1016/j.tecto.2025.231045

Filippos Vallianatos , Vasilis Kapetanidis , Georgios Michas , Andreas Karakonstantis

On 27 September 2021, a damaging earthquake of M_w6.0 struck central Crete (Greece), close to Arkalochori village; the strongest earthquake ever recorded in this area during the instrumental period. Remarkably, the mainshock was preceded by an intense foreshock swarm that lasted almost four months. However, the lack of local seismological stations severely limited the event-detection capability of conventional methods, rendering an in-depth analysis of the foreshocks' evolution and statistical properties unfeasible. To enrich the seismic catalog, we employed a deep-learning model to detect and pick additional seismic phases automatically. A Bayesian Gaussian Mixture Model was then applied to associate the acquired P- and S-wave picks with specific event origins, followed by single-event location with a local 1D velocity model and double-difference relocation. A new, deep-learning catalog was constructed, with about ten times more events than in the previously published seismic catalogs. The evolution of the swarm presented a complex spatiotemporal pattern, with patches activated at different times. A major M_w4.9 foreshock occurred on 24 July 2021, triggering its own sub-sequence. In addition, the b-value spatiotemporal variations were investigated as possible stress state indicators in the seismogenic area. The analysis revealed persistent lower b-values than the background during the foreshock swarm, with the lowest just before the occurrence of the major M_w4.9 foreshock. Furthermore, the b-values spatial distribution highlighted that both the M_w4.9 foreshock and the M_w6.0 mainshock occurred in low b-value zones, suggesting an increased likelihood of occurrence and a critical accumulation of stress in the epicentral areas of the strongest events.

2021年9月27日，希腊克里特岛中部发生6.0级破坏性地震，靠近Arkalochori村；这是有仪器记录以来该地区最强的地震。值得注意的是，主震之前有一个持续了近四个月的强烈前震群。然而，当地地震台站的缺乏严重限制了传统方法的事件探测能力，使得对前震演化和统计特性的深入分析变得不可行。为了丰富地震目录，我们采用了深度学习模型来自动检测和选择额外的地震相位。然后应用贝叶斯高斯混合模型将获取的P波和s波拾取与特定事件起源关联起来，然后使用局部一维速度模型和双差重定位进行单事件定位。建立了一个新的深度学习目录，其中的事件数量是以前发布的地震目录的十倍。蜂群的演化呈现出复杂的时空格局，斑块在不同的时间被激活。2021年7月24日发生了一次Mw4.9级的大前震，触发了它自己的子序列。此外，还研究了b值的时空变化作为发震区应力状态的可能指标。分析显示，在前震群期间，b值持续低于背景值，最低的是在Mw4.9大前震发生之前。此外，b值空间分布突出表明，Mw4.9前震和Mw6.0主震均发生在低b值区域，表明最强地震的震中区域发生的可能性增大，且存在临界应力积累。

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引用次数: 0

Distinct destruction mechanism in the North China Craton: Insight from high-resolution thermochemical structure 华北克拉通独特的破坏机制：来自高分辨率热化学结构的洞察

IF 2.6 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Tectonophysics

Pub Date : 2025-12-18 DOI: 10.1016/j.tecto.2025.231042

Xiaoyu Yang , Yonghua Li , Juan Carlos Afonso

Despite numerous studies on the thinning and destruction of the lithospheric mantle root beneath the North China Craton (NCC), the mechanisms for modification from refractory mantle of ancient craton to the fertile one remains poorly understood due to insufficient information of deep thermochemical structure. We investigate the mantle compositional and thermal structure of the NCC by jointly inverting Rayleigh wave dispersion, geoid height, elevation and surface heat flow (SHF) using a probabilistic inversion. We image significant differences in the thermochemical structure of lithosphere in the different blocks of the NCC. The lithospheric structure of the western North China Craton (WNCC) is dominated by relatively thick lithospheric roots (>150 km) and depleted composition (Mg# ∼90–92), supporting the idea of the core of the WNCC is well-preserved. We observe a relatively thinner lithosphere (<100 km) and more fertile signature in the central and eastern NCC, confirming that these areas have undergone lithospheric thinning and modification. We reveal the distinct lithospheric composition in the central and eastern NCC, indicating the difference of mechanisms of lithospheric reactivation. The low Mg# (Mg# ∼88.5–90) of the lithospheric mantle beneath the eastern North China Craton (ENCC) imply that the cratonic root were delaminated and replaced by a new fertile mantle. The coexistence of depleted and fertile mantle (Mg# ∼88.5–91.5) beneath the central NCC, implying that the depleted cratonic mantle partially evolved to fertile one through injection of melts/fluids originating from the asthenospheric mantle.

尽管对华北克拉通岩石圈地幔根的减薄和破坏进行了大量的研究，但由于对深部热化学结构的了解不足，对古克拉通由难熔地幔向肥沃地幔转变的机制仍然知之甚少。利用概率反演方法反演瑞利波频散、大地面高度、高程和地表热流（SHF），研究了NCC的地幔成分和热结构。研究结果表明，在北陆盆地不同地块，岩石圈热化学结构存在显著差异。华北克拉通西部岩石圈结构以相对较厚的岩石圈根（>150 km）和贫化成分（Mg# ~ 90-92）为主，支持了岩石圈核心保存较好的观点。我们观察到北中、东部岩石圈相对较薄（约100 km），岩石圈特征更为丰富，证实这些地区岩石圈经历了减薄和改造。揭示了北中、东部岩石圈组成的差异性，表明岩石圈活化机制的差异性。华北克拉通东部岩石圈地幔的低Mg# （Mg# ~ 88.5-90）表明克拉通的根被剥离并被新的肥沃地幔所取代。NCC中央下方贫地幔与富地幔共存（Mg# ~ 88.5 ~ 91.5），表明贫克拉通地幔通过注入源自软流圈地幔的熔体/流体而部分演化为富地幔。

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引用次数: 0