Journal of Structural Geology最新文献_第2页

Microstructural, compositional and textural inheritance in deformed mafic amphibolites 变形基性角闪岩的显微结构、组成和结构继承

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-04-01 Epub Date: 2026-01-23 DOI: 10.1016/j.jsg.2026.105630

Laura Airaghi, Hugues Raimbourg, Jacques Précigout

This study investigates the scales of compositional equilibria and the role of early hydration for the development of microstructures and mineral fabrics in mafic amphibolites, all deformed along a major tectonic plate boundary (Hokkaido, Japan). From fractured domains to mm-size shear bands and meter-size shear zones, element and cathodoluminescence mapping, as well as thermodynamic modelling show that both in plagioclase and in amphibole, strong compositional gradients were observed at the smallest (10–200 μm) scale, which in many instances were inherited from an early, static stage of fracturing, hydration and replacement of igneous minerals. Phase distribution and grain sizes in shear bands and shear zones were also inherited from this early metamorphic stage, giving rise to: (1) monomineralic amphibole layers derived from amphiboles replacing aggregates of Fe-Mg igneous minerals in metagabbros, (2) monomineralic plagioclase layers derived from plagioclase-rich domains of metagabbros that experienced limited early breakdown reactions and (3) intimately mixed and fine-grained amphibole-plagioclase layers developed only where symplectites after igneous minerals were previously formed. While crystallographic and shape preferred orientations of amphibole were acquired from early fracture-driven reactions, and then strengthened in shear bands/zones by dissolution-precipitation, nucleation and oriented growth, the ones of plagioclase, whose reaction was incomplete in fractured domains, continued to evolve with increasing viscous strain and reaction progress. Where plagioclase experienced early, partial breakdown, viscous strain was further accommodated by dissolution-precipitation and phase nucleation. In contrast, where igneous plagioclase was largely preserved, crystal plastic deformation accompanied dissolution-precipitation. Heterogeneous early hydration of mafic rocks led therefore to a patchwork of local reacted domains, where inherited microstructures gave rise to heterogeneous phase distribution, grain sizes, fabrics and preconditioned the rock for strain partitioning, and hence, strain localization at a scale of hundreds of microns. In particular, phase mixing was the product not of strain, but rather of an initial stage of chemical reactions.

本研究探讨了基性角闪岩中成分平衡的尺度和早期水化作用对微结构和矿物组构发育的影响，这些角闪岩都是沿着一个主要构造板块边界（日本北海道）变形的。从断裂区域到毫米级剪切带和米级剪切带，元素和阴极发光图以及热力学模拟表明，在斜长石和角闪洞中，在最小（10-200 μm）尺度上观察到强烈的成分梯度，在许多情况下，这些梯度继承于早期的静态压裂、水化和火成岩矿物替代阶段。剪切带和剪切带的物相分布和晶粒尺寸也继承自这一早变质阶段，形成：(1)单矿物角闪石层由角闪石取代偏长岩中Fe-Mg火成岩矿物的聚集物形成；(2)单矿物斜长石层由富含斜长石的偏长岩域形成，经历了有限的早期破碎反应；(3)密切混合的细粒角闪石-斜长石层仅在火成岩矿物后的复晶岩形成的地方发育。角闪石的结晶学和形状择优取向是在早期断裂驱动反应中获得的，然后在剪切带/带中通过溶解-沉淀、成核和取向生长得到强化，而斜长石的结晶学和形状择优取向是随着断裂域中反应不完全的黏性应变的增加和反应的进行而继续演化的。当斜长石经历早期的部分击穿时，黏性应变进一步被溶解-析出和相成核所调节。而火成岩斜长石保存较多的地方，晶体塑性变形伴随溶蚀沉淀。因此，基性岩石的早期非均质水化导致局部反应域的拼凑，其中继承的微观结构产生了非均质相分布、晶粒尺寸、织构，并为岩石的应变分配提供了条件，因此，应变局部化在数百微米的尺度上。特别是，相混合不是应变的产物，而是化学反应初始阶段的产物。

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引用次数: 0

Pre-Neogene tectonics and early broken foreland basin stages in the Bermejo basin 贝尔梅霍盆地前新近纪构造与早期破碎前陆盆地阶段

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2025-12-23 DOI: 10.1016/j.jsg.2025.105612

Marcelo Gonzalez , Federico Lince Klinger , Cinthya Moreno , Franco Clavel , Federico Morales , Cristian Ortiz , Guido Gianni , Miguel Ramos

Broken foreland basins develop in response to far-field compressional stresses from active margins, resulting in deep-seated intraplate contractional structures that fragment the original foreland basin. This study investigates the tectono-sedimentary evolution of the Bermejo Basin, the first recognized broken foreland basin in South America, situated between the Eastern Precordillera and Western Pampean Ranges. Through the reprocessing of seismic data and gravity analyses, we identify three main tectono-sedimentary stages: Stage 1 (Pre-Neogene), Stage 2 (19-4 Ma), and Stage 3 (4–2.5 Ma to Present). Stage 1 generated structures that were buried and subsequently reactivated during Stage 2. This latter stage marked a significant reconfiguration of the basin with progressive northward propagation of compressional structures and a major shift in basin polarity around 6-5 Ma. These stages correspond to varying configurations of the Andean subduction zone, with strong foreland compression linked to flat subduction. However, the mild initial compression of a key structure active since 19-17 Ma, as evidenced by syntectonic strata, suggests that the foreland remained responsive to compressional forces transmitted from the plate margin during episodes of normal subduction. Our findings underscore the previously unrecognized role of inherited (or pre-Andean) compression in the evolution of the Bermejo Basin and provide evidence for a hybrid deformation style affecting the Eastern Precordillera, impacting the western margin of this basin. This study emphasizes the need for updated regional kinematic models that account for the interplay of ancient and more recent tectonic processes in the Bermejo Basin. Finally, our observations indicate that inherited compressional structures, such as the Carboniferous-Permian faults and the early Miocene Alto del Jumeal Range, have played a significant role in guiding subsequent deformation and sedimentation within the Bermejo basin.

破碎前陆盆地是在活动边缘的远场挤压应力作用下发育的，形成了将原始前陆盆地破碎的深层板内收缩构造。本文研究了Bermejo盆地的构造-沉积演化。Bermejo盆地是南美洲第一个被发现的破碎前陆盆地，位于东部Precordillera山脉和西部Pampean山脉之间。通过对地震资料的再处理和重力分析，我们确定了三个主要的构造沉积阶段：第1阶段（前新近纪）、第2阶段（19-4 Ma）和第3阶段（4-2.5 Ma至今）。第一阶段产生了埋藏的结构，随后在第二阶段重新激活。这一阶段标志着盆地的重大重构，挤压构造向北扩展，盆地极性在6-5 Ma左右发生重大转变。这些阶段对应于安第斯俯冲带的不同构造，强烈的前陆挤压与平坦的俯冲有关。然而，同构造地层表明，19-17 Ma以来活跃的关键构造的轻微初始压缩表明，在正常俯冲期间，前陆仍然对板块边缘传递的挤压力作出反应。我们的发现强调了继承（或前安第斯）挤压在Bermejo盆地演化中的作用，并为影响东部前科迪勒拉的混合变形样式提供了证据，影响了该盆地的西缘。这项研究强调需要更新的区域运动学模型，以解释贝尔梅霍盆地古代和近代构造过程的相互作用。结果表明，石炭-二叠纪断裂和早中新世Alto del Jumeal山脉等挤压构造对Bermejo盆地的后续变形和沉积起着重要的指导作用。

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引用次数: 0

Variscan superposition on ordovician extensional fault-related folds in the Eastern Pyrenees 东比利牛斯山奥陶系伸展性断裂相关褶皱上的瓦里斯坎叠加

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2026-01-20 DOI: 10.1016/j.jsg.2026.105629

Pablo Granado , Josep Maria Casas , Marco de Matteis , Òscar Gratacós

Our study investigates pre-Variscan Ordovician tectonics in the La Molina area (Eastern Pyrenees, Spain) by means of geological mapping and structural analysis of mesostructural data. We revisit the structural interpretation of pre-Upper Ordovician folds, revealing two mutually orthogonal, cleavage-free fold systems (WNW–ESE and NNE–SSW striking) affecting the Late Cambrian to Early Ordovician Serdinya Formation. These folds are interpreted as fault-related folds formed above steeply-dipping extensional faults during Mid Ordovician rifting. The geometry and orientation of Variscan mesostructures are shown to be strongly influenced by these earlier Ordovician folds, explaining the wide dispersion of fold axes and cleavage-bedding intersection lineations only found below the Upper Ordovician unconformity. The Upper Ordovician unconformity seals and locally erodes the limbs of those pre-existing folds. The hectometric to kilometric scale cleavage-free Ordovician folds contrast with the finer smaller-scale Variscan syn-foliar folds, and thus explains the absence of fold interference patterns. This work highlight that collecting and analysing detailed mesostructural data in orogenic hinterlands remains essential for interpreting regional tectonics, and it advances our understanding of the early tectonic evolution of the northern Gondwana margin.

本文通过地质填图和细构造资料的构造分析，对西班牙东比利牛斯山脉La Molina地区前瓦里斯坎奥陶系构造进行了研究。通过对上奥陶统前褶皱的构造解释，揭示了影响晚寒武世至早奥陶世Serdinya组的两个相互正交的无解理褶皱体系（WNW-ESE和NNE-SSW走向）。这些褶皱被解释为中奥陶世裂陷期间在陡倾伸展断裂上形成的断层相关褶皱。瓦里斯坎细观构造的几何形状和方向受到这些早奥陶世褶皱的强烈影响，这解释了褶皱轴和理理交错线的广泛分布，这些线只在上奥陶世不整合面下方发现。上奥陶统不整合封闭并局部侵蚀了原有褶皱的分支。奥陶纪的百米至千米尺度的无解理褶皱与较小尺度的瓦里斯坎同叶褶皱形成对比，从而解释了褶皱干涉模式的缺失。这项工作强调了在造山带腹地收集和分析详细的细观构造数据对于解释区域构造是至关重要的，它促进了我们对冈瓦纳北部边缘早期构造演化的理解。

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引用次数: 0

Quantifying finite strain in the poly-deformed Lansdowne Klippe, Garhwal Himalaya, India: An appraisal of popular strain estimation techniques 定量有限应变在多变形的Lansdowne Klippe， Garhwal喜马拉雅，印度：流行的应变估计技术的评价

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2025-12-11 DOI: 10.1016/j.jsg.2025.105585

Sayandeep Banerjee , Sayan Maity , Ashish Rawat , Virendra Rana , Yaspal Sundriyal , Hari B. Srivastava

Understanding finite strain in poly-deformed terranes remains a challenge due to multiple deformation phases, impacting accurate estimation. This study presents a comparative analysis of four distinct techniques (Rf/Φ, Fry's, Panozzo, and AMS-based strain estimation) to estimate the finite strain in the Lansdowne Klippe of the Garhwal Himalaya, India. In the estimation of strain, complexities might arise due to the inherent difficulties in assessing the original shape of strain indicators in areas with a history of multiple deformations. Such challenges significantly affect the precision of finite strain estimation, leading to inconsistencies in the obtained values. By analysing the quantitative and qualitative differences among the methodologies, this study reveals the discrepancies in determining 2-D finite strain and respective strain ellipses. The present attempt is the first rigorous multi-method comparison for quantifying strain within a poly-deformed klippe in the Himalayan orogen. In our comparative analysis, Rf/Φ and Fry methods yielded the highest finite strains (Rs ∼1.7–2.3), whereas the Panozzo method gave lower values (Rs ∼1.1–2.0). AMS-derived anisotropy (Pj ∼1.05–1.2) corresponds to only low finite strain. These systematic method-dependent differences underscore that strain magnitudes in a polyphase terrane are strongly influenced by the chosen technique. Our findings also highlight the inherent inconsistencies and limitations in estimating finite strain in regions with polyphase deformation.

在多变形地形中，由于存在多个变形阶段，因此理解有限应变仍然是一个挑战，影响了准确的估计。本研究提出了四种不同的技术（Rf/Φ， Fry's， Panozzo和基于ams的应变估计）的比较分析，以估计印度Garhwal喜马拉雅地区Lansdowne Klippe的有限应变。在应变估计中，由于在具有多次变形历史的区域中评估应变指标的原始形状存在固有的困难，可能会产生复杂性。这些挑战严重影响了有限应变估计的精度，导致所得值不一致。通过分析这些方法在定量和定性上的差异，揭示了在确定二维有限应变和各自的应变椭圆时的差异。目前的尝试是第一次对喜马拉雅造山带多变形断裂带的应变进行定量的严格的多方法比较。在我们的比较分析中，Rf/Φ和Fry方法产生了最高的有限应变（Rs ~ 1.7-2.3），而Panozzo方法给出了较低的值（Rs ~ 1.1-2.0）。ams衍生的各向异性（Pj ~ 1.05-1.2）只对应于低有限应变。这些系统的方法相关的差异强调了多相岩层中的应变大小受到所选技术的强烈影响。我们的研究结果还强调了在多相变形区域估计有限应变的固有不一致性和局限性。

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引用次数: 0

Comparative studies of salt pillows in proximity to the Ringkøbing-Fyn High, Denmark 丹麦Ringkøbing-Fyn高地附近盐枕的比较研究

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2025-12-15 DOI: 10.1016/j.jsg.2025.105609

Cecilia E.B. Nielsen, Ole R. Clausen

The salt structures in Denmark have become of increased interest for the current Carbon Capture and Storage (CCS) investigations, with most of the prospecting areas being in close relation to the structures. In this study we have investigated three salt pillows located on both sides of the Ringkøbing-Fyn High (RFH), Denmark, with focus on the timing and direction of salt movement. With the use of interpretation and restoration software, we have interpreted multiple 2D seismic lines and made a structural restoration of a defining line for each structure to determine the evolution of the salt movement. Our results show that the structures closest to the RFH have been created by Triassic gravitational gliding of the salt away from the high, while the salt further north most likely initiated by a combination of differential loading and local tectonics during the same period. Salt reactivation is more pronounced for the structures located north of the RFH, especially showing salt reactivation after the deposition of the late Cretaceous Chalk Group indicating a Cenozoic process only affecting the salt structures north of the high. However, the overall deformation of the three structures shows similar patterns, indicating that they all might represent structures located at the border zone of the Permian Zechstein salt basins, thus pushing the influence of the Sorgenfrei-Tornquist Zone in the Norwegian-Danish Basin much further west in the Norwegian-Danish basin than formerly understood.

丹麦的盐结构已成为当前碳捕集与封存（CCS）调查中日益增加的兴趣，大多数勘探区都与盐结构密切相关。在这项研究中，我们调查了位于丹麦Ringkøbing-Fyn高地（RFH）两侧的三个盐枕，重点研究了盐运动的时间和方向。利用解释和恢复软件，我们解释了多条二维地震线，并对每个结构的定义线进行了结构恢复，以确定盐运动的演变。我们的研究结果表明，最接近RFH的构造是由三叠纪盐远离高点的重力滑动造成的，而更北的盐很可能是由同一时期的差异荷载和局部构造共同形成的。盐的再激活作用在RFH以北的构造中更为明显，特别是在晚白垩世白垩群沉积后，表明新生代的盐的再激活作用只影响到高北的盐构造。然而，三个构造的整体变形模式相似，表明它们都可能代表了位于二叠纪Zechstein盐盆地边界带的构造，从而将挪威-丹麦盆地的Sorgenfrei-Tornquist带的影响推到了挪威-丹麦盆地的西部，比以前认识的要远得多。

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引用次数: 0

Extrusion of high-grade metamorphic and anatectic rocks during inclined transpression in the central Brasília Orogen, Western Gondwana 西冈瓦纳Brasília造山带中部斜挤压过程中高变质岩和无水岩的挤压作用

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2026-01-09 DOI: 10.1016/j.jsg.2026.105626

Fernando Resende Honorato , Marco Antônio Delinardo da Silva , Ticiano José Saraiva dos Santos , João Victor Oliveira Cunha , Ewerton Benetti Poloni , Pamela Pavanetto

Ancient and modern orogens are related to transpressional tectonics due to the Earth's spherical surface, often recording synchronous deformation, metamorphism, and anatexis. In the western Gondwana supercontinent, such relations are found in the Brasília Orogen, which formed from the collision between the Paranapanema, São Francisco-Congo, and Amazonian paleoplates during the Neoproterozoic Brasiliano/Pan-African Cycle. This study aims to investigate the deformational, metamorphic, and anatectic processes active in the central Brasília Orogen through field-based geological mapping and structural analysis, petrography, and U-Pb geochronology in zircon. The data show that the internal zone of the central Brasília Orogen underwent crustal shortening in the northeast-southwest direction, synchronous with lateral escape tectonics toward the southeast, suggesting an inclined transpressional context involving strain partitioning and the extrusion of deep-to-middle crustal rocks. The structural evolution was coeval with upper amphibolite to granulite facies metamorphism and anatexis, suggesting spatial and temporal relationships between structural fabrics, metamorphic and anatectic products. In this scenario, structures acted as primary controls of melt migration and granite emplacement, just as melt weakened the crust and facilitated structure nucleation. The Tonian (ca. 0.88 and 0.80 Ga) mafic protolith of the migmatitic orthogneiss and its leucosomes together with the migmatitic paragneiss and syntectonic granites confined the feedback loop between active ductile deformation, metamorphism and anatexis to the Cryogenian and Ediacaran periods (ca. 0.65 to 0.62 Ga), broadly constraining the interval of expressive crustal flow in the Brasilia Orogen.

由于地球是球形的，古代和现代造山带都与逆转构造有关，经常记录同步变形、变质作用和深熔作用。在冈瓦纳超大陆西部，这种关系在Brasília造山带中发现，该造山带是新元古代巴西利亚/泛非旋回期间由巴拉那帕内玛、弗朗西斯科-刚果古板块和亚马逊古板块碰撞形成的。本研究旨在通过野外地质填图、构造分析、岩石学、锆石U-Pb年代学等研究活动在Brasília造山带中部的变形、变质和析成岩过程。研究结果表明，Brasília造山带中部内带在东北—西南方向发生了地壳缩短，与东南方向的侧向逸出构造同步，表明该构造具有应变分区和深—中地壳挤压的斜转构造背景。构造演化与上部角闪岩-麻粒岩相变质和深熔作用同步，表明构造组构、变质和深熔产物之间存在时空关系。在这种情况下，构造是熔体迁移和花岗岩侵位的主要控制因素，就像熔体削弱地壳并促进构造成核一样。混合岩正长岩的东系（约0.88和0.80 Ga）基性原岩及其白色小体与混合岩副长岩和同构造花岗岩将活跃的韧性变形、变质作用和深熔作用的反馈回路限定在深冷系和埃迪卡拉系（约0.65 ~ 0.62 Ga），广泛地限制了巴西利亚造山带表现性地壳流动的间隔。

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引用次数: 0

Ultracataclastic vein evolution within a granodiorite along the Naxos-Paros Detachment System 纳克索斯-帕罗斯滑脱系花岗闪长岩内超碎屑脉演化

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2025-12-30 DOI: 10.1016/j.jsg.2025.105613

O. Rolfe , R. Dubosq , D.A. Schneider , S. Zaefferer , B. Grasemann

Ultracataclastic and pseudotachylytic veins are interpreted as direct evidence of coseismic slip, reflecting the conditions and mechanisms associated with fault rupture. Although the Naxos granodiorite, Greece, is known for its pristine pseudotachylyte exposures, these features remain largely understudied in terms of their microstructural evolution and implications for upper and middle crustal seismicity. We examine a suite of well-preserved veins hosted in the deformed Miocene granodiorite, historically described as examples of melt-origin pseudotachylytes, but here are re-interpreted as dominantly ultracataclasites, produced from the comminution of host rock. The veins occur in the immediate footwall of the fluid-rich, low-angle Naxos-Paros Detachment System, active between c. 20-10 Ma, and possess a similar composition as the surrounding host rock of primarily albite (35%), quartz (25%), orthoclase (16%), and biotite (12%). Structural field observations from the highest strain zone reveal three distinct crosscutting vein sets. Electron backscatter diffraction mapping of host rock porphyroclasts of albite, orthoclase, and quartz crosscut by ultracataclastic veins demonstrates that cataclasis is the dominant deformation mechanism. Variations in microstructural maturity of vein fragments suggest episodic emplacement, with rupture exploiting pre-existing slip planes. Cuspate phase boundaries between orthoclase and albite, initially observed in optical and scanning electron microscopy, are confirmed by electron microprobe analyses as a result from dissolution-precipitation reactions. These features indicate deformation by dissolution-precipitation creep. The results suggest that fluid-mediated reactions localized at vein tips contributed to weakening, generating a mechanical-chemical feedback loop that promoted ultracataclastic vein propagation along the detachment.

超碎裂和伪碎裂脉被解释为同震滑动的直接证据，反映了断层破裂的相关条件和机制。尽管希腊纳克索斯花岗闪长岩以其原始的伪长岩暴露而闻名，但就其微观结构演化及其对上、中地壳地震活动的影响而言，这些特征仍未得到充分研究。我们研究了一组保存完好的矿脉，这些矿脉位于变形的中新世花岗闪长岩中，在历史上被描述为熔体成因的伪长岩的例子，但在这里被重新解释为主要是由宿主岩石粉碎产生的超碎屑岩。脉体赋存于富流体、低角度的纳克索斯-帕罗斯滑脱系的直接下盘，活动时间为约20 ~ 10 Ma，其组成与围岩相似，主要为钠长石（35%）、石英（25%）、正长石（16%）和黑云母（12%）。从最高应变区进行的构造现场观测显示出三个不同的横切脉组。利用超碎裂岩脉对钠长石、正长石和石英等围岩斑状碎屑进行电子背散射成像，结果表明碎裂作用是主要的变形机制。微观结构成熟度的变化表明静脉碎片是幕式就位的，破裂利用了先前存在的滑动面。在光学和扫描电子显微镜中观察到的正长石和钠长石之间的尖形相界，通过溶解-沉淀反应的电子探针分析得到了证实。这些特征表明变形是由溶解-沉淀蠕变引起的。结果表明，位于静脉尖端的流体介导的反应有助于减弱，产生了一个机械-化学反馈回路，促进了超塑性静脉沿着脱离体传播。

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引用次数: 0

Rift development at the Askja Fissure Swarm, Iceland 冰岛Askja裂缝群的裂谷发育

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2026-01-10 DOI: 10.1016/j.jsg.2026.105623

Fabio Luca Bonali , Martina Pedicini , Thomas R. Walter , Alessandro Tibaldi

Understanding how faulting and dyke intrusion interact to control rift development in volcanotectonic systems remains a key challenge, particularly in areas where multiple magma sources coexist. Here, we contribute to this topic by providing a high-resolution structural dataset for the Askja Fissure Swarm (AFS), one of the major rifts of the Northern Volcanic Zone of Iceland (NVZ), where central volcanoes and their associated dyke-fissure swarms act as magma plumbing systems and long-term eruption sources. We describe the Holocene structures of the AFS through the analysis of high-resolution remote sensing data and virtual field reconnaissance. We developed an inventory of 3749 individual structures, including dykes and fractures, mapped at a scale of 1:50,000, and systematically measured their strike, dip direction, length and kinematics. We recognized 395 eruptive fissures, 2301 extension dry fractures (fissures), and 1038 normal faults, of which 536 dip eastward and 502 westward. Along the main faults, we reconstructed the slip profiles, with the aim of evaluating the direction of along-axis fault and rift propagation. The overall dataset exhibits a predominant N–S to NNE–SSW strike, with an average strike of N17.5°E. Structure lengths vary from 10 m up to 13 km, with a mean of 445 m. Normal faults are generally longer than other structures, with a mean of 1042 m. With distance to the central volcanoes, we find the number of extension fractures and faults, their lengths and the slip profiles decrease. We interpret these characteristics as the effect of multiple dykes that laterally propagated outward from the magma chambers below Askja and Hrúthálsar central volcanoes. We also observed variation of fracture intensity and strike where the AFS intersects possibly hidden inherited transversal structures. Looking at the whole AFS, the tapering of fault slip profiles shows a dominant northward propagation of faults. This may indicate the superimposition of a regional northward propagation of the rift on the local effects of dykes and magma chambers, consistent with the northward spread of the NVZ.

了解断裂和岩脉侵入如何相互作用以控制火山构造系统中的裂谷发育仍然是一个关键的挑战，特别是在多个岩浆源共存的地区。在这里，我们通过为冰岛北部火山区（NVZ）的主要裂缝之一Askja裂缝群（AFS）提供高分辨率结构数据集来为这一主题做出贡献，其中中央火山及其相关的脉裂群充当岩浆管道系统和长期喷发源。通过对高分辨率遥感数据的分析和虚拟野外侦察，描述了AFS的全新世结构。我们编制了3749个独立构造的清单，包括堤防和裂缝，以1:5万的比例绘制，并系统地测量了它们的走向、倾斜方向、长度和运动学。发现喷发裂缝395条，伸展干裂缝2301条，正断层1038条，其中东倾536条，西倾502条。沿着主要断层重建了断层滑动剖面，目的是评估断层沿轴方向和裂谷的扩展。整个数据集以北南至北北-南南西走向为主，平均走向为N17.5°E。结构长度从10米到13公里不等，平均长度为445米。正断层一般比其他构造长，平均为1042米。随着离中心火山的距离增加，伸展断裂和断裂的数量、长度和滑动剖面减少。我们将这些特征解释为从Askja和Hrúthálsar中心火山下方的岩浆房向外横向传播的多个岩脉的影响。我们还观察到断裂强度和走向的变化，在AFS相交的地方可能隐藏着继承的横向构造。从整个AFS来看，断层滑动剖面的逐渐变细表明断层主要向北传播。这可能表明，裂谷的区域向北扩展叠加在岩脉和岩浆房的局部影响上，与NVZ向北扩展相一致。

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引用次数: 0

Slab kinematics and strain localization in NE China: Polyphase deformation of the Hulin Complex during Late Mesozoic subduction 中国东北板块运动与应变局部化：晚中生代俯冲期间虎林杂岩的多期变形

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2026-01-02 DOI: 10.1016/j.jsg.2025.105614

Wei Pi , Han Zheng , Jian Zhang , Zhiyuan He , Johan De Grave , Ian P. Cawood , Yong Liang , Heng Peng , Guochun Zhao

Crustal shear zones in Northeast China preserve a critical record of Paleo-Pacific subduction, yet distinguishing the superimposed tectonic fabrics remains a challenge. We resolved this by reconstructing the structural and thermal history of the Hulin Complex, linking local deformation directly to specific slab dynamics. During the Late Jurassic to Early Cretaceous (D₁: ca. 160–130 Ma), a moderate oblique subduction angle (∼30–40°) drove NE–SW sinistral transpression. This phase produced distributed general shear (Flinn's k = 0.73–0.91; W_k = 0.64–0.67) under mid-crustal conditions (∼350–500 °C), accommodated by quartz rhomb <a> and prism <a> slip at differential stresses of 15–18 MPa. In the Cretaceous (D₂: ca. 130–85 Ma), accelerated SE-directed slab rollback stretched the lithosphere, triggering regional extension (Flinn's k = 0.85–1.01; W_k = 0.57–0.62). Strain localized into weak, mica-rich zones (>15 vol%) as differential stresses dropped to 13–14 MPa and temperatures cooled to 300–400 °C. This extension facilitated synchronous magmatism. By the Late Cretaceous (D₃: ca. 85–68 Ma), a shift to W–NW subduction created a lower obliquity angle (∼20–30°). This renewed dextral transpression reactivated older structures in the mid-to-lower crust (≤300–400 °C) but at significantly higher stresses (21–34 MPa). Quartz fabrics shifted to basal <a> slip, reflecting strain repartitioning (Flinn's k = 0.63–0.76; W_k = 0.67–0.71). Our findings demonstrate that shear zone evolution is governed by specific subduction parameters: (1) shallower slab dips enhance coupling to localize strain; (2) rapid rollback weakens the lithosphere to drive extension; and (3) high convergence obliquity (angles <30°) amplifies the simple shear component. Thus, the Hulin Complex acts as a sensitive rheological recorder, capturing the changing tempo and geometry of the subducting slab.

中国东北的地壳剪切带保存了古太平洋俯冲的重要记录，但区分叠合构造仍然是一个挑战。我们通过重建虎林杂岩的结构和热历史来解决这个问题，将局部变形直接与特定的板动力联系起来。晚侏罗世至早白垩世（D1：约160 ~ 130 Ma），一个中等斜向俯冲角（~ 30 ~ 40°）驱动了NE-SW左旋转动。该相在中地壳条件下（~ 350 ~ 500°C）产生了分布的总剪切（Flinn’s k = 0.73-0.91; Wk = 0.64-0.67），在15 ~ 18 MPa的差应力下，由石英菱形和棱形滑移（<a>；和棱镜<；a>；滑移）所适应。在白垩纪（D2：约130 ~ 85 Ma），加速的东南向板块回滚拉伸了岩石圈，引发了区域伸展（Flinn’s k = 0.85 ~ 1.01; Wk = 0.57 ~ 0.62）。当差应力降至13-14 MPa，温度降至300-400°C时，应变局部定位到弱的富云母区（>15 vol%）。这种扩展促进了同步岩浆活动。到晚白垩世（D3：约85-68 Ma），向W-NW俯冲的转变产生了较低的倾角（~ 20-30°）。这种更新的右旋转活动重新激活了中下地壳（≤300-400°C）的旧构造，但在明显更高的应力下（21-34 MPa）。石英织物向基底滑动，反映应变重新分配（Flinn’s k = 0.63-0.76; Wk = 0.67-0.71）。研究结果表明，剪切带的演化受特定俯冲参数的控制：(1)较浅的板块倾角增强了局部应变的耦合；(2)快速回滚削弱岩石圈，推动伸展；(3)高辐合倾角（角<；30°）放大了简单剪切分量。因此，虎林杂岩充当了一个敏感的流变记录仪，捕捉俯冲板块的变化速度和几何形状。

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引用次数: 0

Rethinking the crustal architecture of the Neoproterozoic gneiss domes in the Nubian Shield: Constraints from the Meatiq dome, Egypt 重新思考努比亚地盾新元古代片麻岩穹丘的地壳结构：来自埃及Meatiq穹丘的约束

IF 2.9 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Journal of Structural Geology

Pub Date : 2026-03-01 Epub Date: 2026-01-03 DOI: 10.1016/j.jsg.2026.105615

Abdullah T. Mohammad , Yahia El Kazzaz

The Nubian Shield hosts amphibolite-grade, gneiss-cored domes surrounded by greenschist-grade island-arc and ophiolitic rocks. These domes record distinctly intense ductile deformation and higher metamorphism compared to adjacent rocks, yet their origin and geometry remain debated. Here we combine field observations, remote sensing, and structural–microstructural analyses to reassess the nature and architecture of these domes, focusing on the Meatiq dome in Central Eastern Desert of Egypt. Our results demonstrate that the dome represents a folded, thrust-related shear zone developed at mid-crustal levels within psammitic–pelitic metasediments overlain by ophiolitic and metavolcanic nappes. Microstructures record crystal-plastic deformation mechanisms at ∼670–450 °C with consistent top-to-NW shear indicators. Syn-kinematic emplacement of the Um Baanib and Abu Ziran granites occurred during NW-directed tectonic transport, with sub-magmatic microstructures recording the transition from magmatic to solid-state deformation. Both plutons display sheet-like geometries, controlled by lithological/rheological boundaries, and were later dissected by brittle thrust slices during doming. Although the Meatiq dome share some similarities with metamorphic core complexes, the absence of low-angle normal faults, rotational blocks, and migmatitic cores, combined with timing constraints, rules out core complex or diapiric origin. Instead, we argue that its domal geometry reflects thrust-related folding and multi-phase deformation associated with NW-directed tectonic transport during the East and West Gondwanaland collision (∼605–596 Ma), later modified by multiple Phanerozoic rifting phases. This evolutionary model highlights thrust-related tectonics as the primary driver of the Meatiq dome and prompts a reassessment of similar domes in the Nubian Shield. In addition, the results have broader implications for understanding gneiss-cored domes in orogenic belts worldwide and dynamic feedback between deformation and magmatism at mid-crustal shear zones.

努比亚地盾拥有角闪岩级、片麻岩芯的圆顶，周围环绕着绿片岩级岛弧和蛇绿岩。与邻近的岩石相比，这些圆顶记录了明显强烈的韧性变形和较高的变质作用，但它们的起源和几何形状仍有争议。在这里，我们结合实地观察、遥感和结构-微观结构分析来重新评估这些圆顶的性质和结构，重点是埃及中东部沙漠的Meatiq圆顶。我们的研究结果表明，在蛇绿岩和变质火山推覆体覆盖的泥质-泥质变质沉积层中，丘顶是一个褶皱的、逆冲相关的剪切带。显微结构记录了在~ 670-450°C的晶体塑性变形机制，具有一致的顶部到nw剪切指标。乌姆巴尼布和阿布兹兰花岗岩的同步运动学侵位发生在北西向构造搬运过程中，次岩浆微结构记录了岩浆向固态变形的过渡。这两个岩体都显示出薄片状的几何形状，受岩性/流变边界的控制，后来在穹隆过程中被脆性逆冲切片解剖。尽管Meatiq圆顶与变质核杂岩有一些相似之处，但由于缺乏低角度正断层、旋转块体和混染岩心，结合时间限制，排除了核杂岩或底辟成因的可能性。相反，我们认为其隆起的几何形状反映了东、西Gondwanaland碰撞（~ 605-596 Ma）期间与北西向构造运输有关的逆冲相关的褶皱和多期变形，后来被多个显生宙裂陷期所修正。这一演化模型强调了与逆冲相关的构造是Meatiq穹窿的主要驱动力，并促使人们重新评估努比亚地盾中类似的穹窿。此外，研究结果对于认识世界范围内造山带的片麻岩核圆顶以及中地壳剪切带变形与岩浆活动的动态反馈具有更广泛的意义。

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引用次数: 0