Tectonics最新文献_第6页

Magmatic, Metamorphic and Structural History of the Variscan Lizard Ophiolite and Metamorphic Sole, Cornwall, UK 英国康沃尔郡瓦里斯坎蜥蜴蛇绿岩和变质岩层的岩浆、变质和构造史

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-04-05 DOI: 10.1029/2023tc008187

Tobermory C. Mackay-Champion, Michael P. Searle, Simon Tapster, Nick M. W. Roberts, Robin K. Shail, Richard M. Palin, George H. Willment, Josh T. Evans

{"title":"Magmatic, Metamorphic and Structural History of the Variscan Lizard Ophiolite and Metamorphic Sole, Cornwall, UK","authors":"Tobermory C. Mackay-Champion, Michael P. Searle, Simon Tapster, Nick M. W. Roberts, Robin K. Shail, Richard M. Palin, George H. Willment, Josh T. Evans","doi":"10.1029/2023tc008187","DOIUrl":"https://doi.org/10.1029/2023tc008187","url":null,"abstract":"The Lizard ophiolite, Cornwall, South-West England, is the largest and best-preserved ophiolite within the Variscan orogenic belt. It forms part of the Rheic-Rhenohercynian suture zone, and was obducted northwestward onto the passive continental margin of Avalonia (Laurussia) during the Middle Devonian. It comprises an almost complete thrust slice of oceanic crust with sheeted dykes, gabbros, Moho transition sequence, and upper-mantle peridotites, underlain by a metamorphic sole. Despite the importance of the Lizard ophiolite in understanding Variscan tectonics, the origin and age of the Lizard ophiolite are debated. We present new field observations, structural maps and cross-sections of the Lizard ophiolite from extensive re-mapping, integrated with U–Pb geochronology, petrology, thermobarometry, and whole rock geochemistry. We report new U–Pb zircon (CA-ID-TIMS and LA-ICPMS) ages of 386.80 ± 0.25/0.31/0.52 Ma (Givetian) from a plagiogranite dyke intruding the Crousa Gabbros at Porthoustock, and 395.08 ± 0.14/0.22/0.47 Ma (Emsian) from partial melts of the metamorphic sole Landewednack Amphibolites at Mullion Cove. These ages, respectively, precisely date the formation of the Lizard ophiolite oceanic crust, and the age of cooling post peak-metamorphism of the sole. Petrological modeling on the Landewednack Amphibolites suggests peak metamorphic conditions of 10 ± 2 kbar and 600 ± 75°C. We demonstrate that the Lizard ophiolite formed as a supra-subduction zone ophiolite overlying an inverted metamorphic sole, and we combine our observations and data into a new geodynamic model for the formation and obduction of the ophiolite. The current data supports an induced subduction initiation model.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"53 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Mega-Folding of a Basement During Incipient Intra-Plate Continental Subduction (Alpine Central Iberia) 板内大陆俯冲初期的基底大褶皱（伊比利亚中部高山地区）

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-04-05 DOI: 10.1029/2023tc008163

Rubén Díez Fernández, Gerardo de Vicente, Diana Moreno-Martín, Carlos Fernández, Ricardo Arenas, Francisco J. Rubio Pascual

{"title":"Mega-Folding of a Basement During Incipient Intra-Plate Continental Subduction (Alpine Central Iberia)","authors":"Rubén Díez Fernández, Gerardo de Vicente, Diana Moreno-Martín, Carlos Fernández, Ricardo Arenas, Francisco J. Rubio Pascual","doi":"10.1029/2023tc008163","DOIUrl":"https://doi.org/10.1029/2023tc008163","url":null,"abstract":"Metamorphic basements are usually considered rigid and isotropic at a large scale. However, basements contain inherited weaknesses that may potentially accommodate superimposed contraction (e.g., fault reactivation), and that favor fold nucleation (e.g., penetrative foliations). If these conditions are met, what could be the factors that impede the development of basement folds or their recognition? Actual basement folding is rarely documented, especially for large dimensions. Here we provide a case example, discussed from the perspective of structural analysis of surface data and sustained by geophysical data. The basement of the Spanish-Portuguese Central System is defined by an Alpine mega-fold (Hiendelaencina Antiform) that trends parallel to this mountain range and affects the basement and its sedimentary cover, collectively. The wavelength of this fold matches or even surpasses the thickness of the crust that hosts it (36–41 km). The Moho under this mega-fold is displaced by an Alpine fault that accounts for incipient intraplate continental subduction. The topography of the mantle may reflect an up-warping compatible with the mega-fold observed on the surface. Mega-folding is observed in the hanging wall of the Berzosa Fault, which emerges as a SE-dipping, Variscan (Paleozoic), extensional fault reactivated as a basal decollement upon Alpine (Cenozoic) contraction. The mega-fold was formed after well-oriented planar anisotropies in the basement (foliation and bedding). The development of this fold was assisted by heterogeneous shearing (coeval thrusting) plus the buttressing effect of pre-existing, near-vertical, crustal-scale faults (Somolinos and Somosierra), which inhibited slip-upsection through the basal decollement (Berzosa Fault).","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"24 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Neogene-Recent Reactivation of Pre-Existing Faults in South-Central Vietnam, With Implications for the Extrusion of Indochina 越南中南部原有断层的新近再活化及其对印度支那挤压的影响

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-04-02 DOI: 10.1029/2023tc008231

Nicholas Richard, Caroline M. Burberry, Nguyen Hoang, Le Duc Anh, Sang Q. Dinh, Lynne J. Elkins

{"title":"Neogene-Recent Reactivation of Pre-Existing Faults in South-Central Vietnam, With Implications for the Extrusion of Indochina","authors":"Nicholas Richard, Caroline M. Burberry, Nguyen Hoang, Le Duc Anh, Sang Q. Dinh, Lynne J. Elkins","doi":"10.1029/2023tc008231","DOIUrl":"https://doi.org/10.1029/2023tc008231","url":null,"abstract":"Vietnam contains complex faults coupled with a diffuse igneous province that has been active since the mid-Miocene. However, existing fault maps demonstrate little consensus over the location of Neogene basalt flows and relative ages of mapped faults, which complicates interpretations of tectonic model for the evolution of Indochina. This paper identifies discrete tectonic blocks within Vietnam and aims to define the Neogene-Recent tectonic setting and kinematics of south-central Vietnam by analyzing the orientation, kinematics, and relative ages of faults across each block. Fault ages and relative timing are estimated using cross-cutting relationships with dated basalt flows and between slickenside sets. Remote sensing results show distinct fault trends within individual blocks that are locally related to the orientations of the basement-involved block-bounding faults. Faults observed in the field indicate an early phase of dip-slip motion and a later phase of strike-slip motion, recording the rotation of blocks within a stress field. Faulting after the change in motion of the Red River Fault Zone at ∼16 Ma is inferred, as faults cross-cut basalt flows as young as ∼0.6 Ma. Strike-slip motion on block-bounding faults is consistent with rotation and continuous extrusion of each block within south-central Vietnam. The rotation of the blocks is attributed to the “continuum rubble” behavior of small crustal blocks influenced by upper mantle flow after the collision between India and Eurasia. We infer a robust lithospheric-asthenospheric coupling in the extrusion model, which holds implications for other regions experiencing extrusion even in the absence of a free surface.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"43 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Age, Kinematic and Thermal Constraints of Syn-Orogenic Low-Temperature Deformation Events: Insights From Thermochronology and Structural Data of the Nekézseny Thrust (Alpine-Carpathian-Dinaric Area) 同源低温变形事件的年龄、运动学和热约束：从内克泽塞尼（阿尔卑斯-喀尔巴阡山-第纳尔地区）隆起的热时学和构造数据中获得的启示

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-28 DOI: 10.1029/2023tc008189

Éva Oravecz, Zsolt Benkó, Róbert Arató, István Dunkl, Gábor Héja, Szilvia Kövér, Tibor Németh, László Fodor

{"title":"Age, Kinematic and Thermal Constraints of Syn-Orogenic Low-Temperature Deformation Events: Insights From Thermochronology and Structural Data of the Nekézseny Thrust (Alpine-Carpathian-Dinaric Area)","authors":"Éva Oravecz, Zsolt Benkó, Róbert Arató, István Dunkl, Gábor Héja, Szilvia Kövér, Tibor Németh, László Fodor","doi":"10.1029/2023tc008189","DOIUrl":"https://doi.org/10.1029/2023tc008189","url":null,"abstract":"Unraveling the age and kinematics of low temperature deformation events is crucial in understanding the late-stage evolution of orogens. However, accurate age constraints can often be challenging to obtain due to unideal outcrop conditions, large sedimentary hiatuses or the lack of well-defined thermal events. In this study, we show on the example of the Nekézseny Thrust, a poorly exposed late orogenic thrust in the southern Western Carpathians, that a combined approach of structural analysis and multi-method thermochronology can provide the necessary temporal, kinematic and thermal constraints for a detailed reconstruction of the deformation history. While structural mapping revealed that the Late Cretaceous Uppony Gosau Basin in the footwall of the Nekézseny Thrust underwent a significant post-Campanian and pre-Miocene shortening, K/Ar dating of fault gouge samples from the main fault zone constrained the primary thrusting event to the Maastrichtian. Based on the acquired apatite fission-track and (U-Th)/He ages, subsequent heating of the Upper Cretaceous sediments due to tectonic burial was limited to 75–100°C, followed by deformation-related and gradual cooling between the Eocene and Early Miocene. Considering the reconstructed deformation history, as well as the large-scale tectonic affinity of the displaced units in its footwall and hanging wall, the Nekézseny Thrust is a far-traveled (ca. 600 km) segment of the Late Cretaceous Alps-Dinarides contact zone, whose development was linked to the switch from lower plate to upper plate position with respect to the Sava Zone and Alpine Tethys sutures, respectively.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"28 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140324773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A Push in the Right Direction: Exploring the Role of Zealandia Collision in Eocene Pacific-Australia Plate Motion Changes 正确方向的推动：探索西兰岛碰撞在始新世太平洋-澳大利亚板块运动变化中的作用

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-23 DOI: 10.1029/2023tc007958

Dan Sandiford, Peter Betts, Joanne Whittaker, Louis Moresi

{"title":"A Push in the Right Direction: Exploring the Role of Zealandia Collision in Eocene Pacific-Australia Plate Motion Changes","authors":"Dan Sandiford, Peter Betts, Joanne Whittaker, Louis Moresi","doi":"10.1029/2023tc007958","DOIUrl":"https://doi.org/10.1029/2023tc007958","url":null,"abstract":"The Pacific Plate underwent a significant change in motion during the early Eocene. This change has been linked to plate boundary reconfiguration, particularly in relation to subduction margins. The reconfiguration also resulted in a new Pacific-Australian plate boundary section transecting Zealandia. Following the Eocene transition, the relative rotation axis was located within continental Zealandia, and it has been hypothesized that this region acted as a pivot point. Here we investigate the extent to which collision resistance along the intra-continental Zealandia margin (length ∼1,000 km) might have impacted the motion of the Pacific Plate, which is characterized by trench lengths more than an order of magnitude greater. We first highlight the relatively large radial component in the Pacific Plate absolute rotation during the period ca. 47 and 32 Ma (i.e., the spin around the plate centroid axis). We then consider how parameterized plate boundary forces impact the tangential and radial components of the net torque (i.e., the fictitious and true torque components). We show that during this period, both the Zealandia and Izu-Bonin-Marianas (IBM) margins of the Pacific Plate were well-oriented in terms of partitioning boundary normal forces into counter-clockwise (CCW) radial torques. This analysis is supported by results from recent global-scale numerical models. The role of Zealandia cannot be established unambiguously, based on our analysis, but effects can be quantified under different assumptions. Collision resistance along the Zealandia margin could plausibly constitute a “first order” effect on Eocene Pacific Plate rotation, albeit only on the radial component.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"55 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The Impact of the Bohemian Spur on the Cooling and Exhumation Pattern of the Eastern Alpine Wedge of the European Alps 波希米亚支脉对欧洲阿尔卑斯山东阿尔卑斯楔形地带的降温和排湿模式的影响

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-18 DOI: 10.1029/2023tc008005

Bianca Heberer, Bernhard C. Salcher, Gabor Tari, Godfrid Wessely, István Dunkl, Reinhard F. Sachsenhofer, Michael Wagreich, Christoph von Hagke

{"title":"The Impact of the Bohemian Spur on the Cooling and Exhumation Pattern of the Eastern Alpine Wedge of the European Alps","authors":"Bianca Heberer, Bernhard C. Salcher, Gabor Tari, Godfrid Wessely, István Dunkl, Reinhard F. Sachsenhofer, Michael Wagreich, Christoph von Hagke","doi":"10.1029/2023tc008005","DOIUrl":"https://doi.org/10.1029/2023tc008005","url":null,"abstract":"Fold and thrust belt architecture may be influenced by basement geometry of the downgoing plate. This influence is notoriously difficult to assess due to a common lack of subsurface constraints and low resolution of exhumation estimates in space and time. The Bohemian Spur is a basement high at the transition from the Alps to the Carpathians. It coincides with narrowing of the foreland basin and an orogen-scale change of strike. Its location in one of the best-studied orogens in the world makes it an ideal case for understanding how basement topography influences fold and thrust belt tectonics. However, since thermochronological studies were mainly focused on the core of the Alps, timing and amount of exhumation remain poorly constrained in these peripheral parts of the orogen. We present new apatite (U-Th)/He and fission track data from the wedge above the Bohemian Spur. Thermally reset ages monitor a so far un(der)appreciated phase of prominent Late Oligocene to Miocene cooling, associated with crustal thickening, uplift and erosion during wedge propagation. Pronounced exhumation on the order of 3–4.5 km can be related to basement steps beneath the advancing wedge. The spur acted as a buttress for foreland-propagating thrusting, pinning deformation and nucleating antiformal stacking and duplexing and thus exhumation above it. We illustrate how along- and across-strike changes of sub-detachment topography impact wedge propagation and control fold and thrust belt geometries. The buttressing effect accounts for most of the exhumation, while deep-seated slab dynamics are of subordinate importance for wedge uplift.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"1 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140172376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Seamount Subduction Dynamics and Long-Term Evolution of the Franciscan Active Margin 海山俯冲动力学与弗朗西斯坎活动边缘的长期演变

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-13 DOI: 10.1029/2023tc008084

G. Bonnet, F. E. Apen, M. Soret, J. Noël, B. Caron, D. Ninkabou, P. Zverev, D. Deldicque

{"title":"Seamount Subduction Dynamics and Long-Term Evolution of the Franciscan Active Margin","authors":"G. Bonnet, F. E. Apen, M. Soret, J. Noël, B. Caron, D. Ninkabou, P. Zverev, D. Deldicque","doi":"10.1029/2023tc008084","DOIUrl":"https://doi.org/10.1029/2023tc008084","url":null,"abstract":"The Snow Mountain Volcanic Complex (SMVC; northern California, USA) is a well-preserved example of a coherently-exhumed subducted seamount. This study reappraises the genesis and evolution of this complex and surrounding units through detailed field, petro-structural and geochronological analyses. This work demonstrates that the SMVC (a) erupted at ∼166 Ma as a hotspot volcano on the Farallon Plate, (b) entered the Franciscan subduction trench at ∼118 Ma, and (c) was subsequently subducted to a depth of ∼20 km (within the seismogenic zone), as shown by local blueschist-facies assemblages formed at 0.6 GPa, 240°C. Transient subduction interfaces are preserved above, within, and below the SMVC, making it an exceptional target to study seamount subduction dynamics. Like other seamounts, the subduction-related deformation was mainly accommodated along kilometer-scale internal thrust zones lubricated by serpentinite/metasediments, and within centimeter-thick crack-seal veins recording pulsed fluid flow near peak metamorphism. No unequivocal proof of seismic activity was found. The integration of other seamounts (some potentially belonging to a former seamount chain) in the Franciscan Complex suggests that exhumed seamounts are more abundant than previously thought. Moreover, pressure-temperature-time estimates of subduction metamorphism for the surrounding units, combined with previous work constrain the thermal maturation of the subduction zone through time and the in-sequence emplacement of the SMVC. Rapid changes in age of the subducted oceanic plate when subducted additionally hint to the subduction of large-offset transform faults on the former Farallon plate. Such a process might have been linked to changes in accretion dynamics and magmatic flare-ups in the arc.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"15 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evidence for a Constant Slip Rate Over the Last ∼40 ka Along the Mt. Morrone Fault System in Central Apennines 亚平宁半岛中部莫罗内山断层系统在过去 ∼40 ka 年间恒定滑动速率的证据

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-09 DOI: 10.1029/2023tc007871

I. Puliti, L. Benedetti, A. Pizzi, J. Fleury, M. Francescone, V. Guillou, Aster Team

{"title":"Evidence for a Constant Slip Rate Over the Last ∼40 ka Along the Mt. Morrone Fault System in Central Apennines","authors":"I. Puliti, L. Benedetti, A. Pizzi, J. Fleury, M. Francescone, V. Guillou, Aster Team","doi":"10.1029/2023tc007871","DOIUrl":"https://doi.org/10.1029/2023tc007871","url":null,"abstract":"Located in the easternmost portion of the Central Apennines, the Mt. Morrone normal fault system is one of the highest seismic hazards in Italy. Previous geological and geomorphological observations revealed the presence of a ∼22 km-long NW-SE right-lateral en echelon fault system made of two parallel faults affecting Quaternary deposits. Our analysis focused on the westernmost fault, which bounds the Sulmona Basin. Cumulative offsets were identified and quantified using high-resolution Digital Elevation Models derived from LiDAR, Satellite Pleiades images, and drone acquisition at the three sites. Morphological markers displaced from a few to tens of meters were dated using 36Cl exposure dating. The results would be suggesting a fault slip rate of 0.2–0.4 mm/a. The deformed markers that dated at 36–44 ka consist of alluvial terraces emplaced by the main streams flowing down from Mt. Morrone to the Sulmona Basin, subsequently incised, and preserved when the fluvial base level dropped because of the former Sulmona lake fluctuations. The yielded ages for these markers fit well with the last major aggradational event associated with the 35–40 ka Heinrich event described and dated to other fluvial basins in the Apennines. Furthermore, the estimated rate agrees with the values obtained in previous studies over shorter and longer periods (105−6 years) and within similar uncertainties. This might then suggest that the period recovered by this study encompasses the entire seismic cycle.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"38 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Surface Rupturing Earthquakes of the Greater Caucasus Frontal Thrusts, Azerbaijan 阿塞拜疆大高加索正面隆起的地表破裂地震

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-09 DOI: 10.1029/2023tc007758

Ian Pierce, Ibrahim Guliyev, Gurban Yetirmishli, Rauf Muradov, Sabina Kazimova, Rashid Javanshir, Gregory P. De Pascale, Ben Johnson, Neill Marshall, Richard Walker, Paul Wordsworth

{"title":"Surface Rupturing Earthquakes of the Greater Caucasus Frontal Thrusts, Azerbaijan","authors":"Ian Pierce, Ibrahim Guliyev, Gurban Yetirmishli, Rauf Muradov, Sabina Kazimova, Rashid Javanshir, Gregory P. De Pascale, Ben Johnson, Neill Marshall, Richard Walker, Paul Wordsworth","doi":"10.1029/2023tc007758","DOIUrl":"https://doi.org/10.1029/2023tc007758","url":null,"abstract":"Here we present the results of the first paleoseismic study of the Kura fold-thrust belt in Azerbaijan based on field mapping, fault trenching, and Quaternary dating. Convergence at rates of ∼10 mm/yr between the Arabian and Eurasian Plates is largely accommodated by the Kura fold-thrust belt which stretches between central Azerbaijan and Georgia along the southern front of the Greater Caucasus (45–48°E). Although destructive historic earthquakes are known here, little is known about the active faults responsible for these earthquakes. A paleoseismic trench was excavated across a 2-m-high fault scarp near Agsu revealing evidence of two surface rupturing earthquakes. Radiocarbon dating of the faulted sediments limits the earthquake timing to AD 1713–1895 and AD 1872–2003. Allowing for uncertainties in dating, the two events likely correspond to historical destructive M ∼ 7 earthquakes near Shamakhi, Azerbaijan in AD 1668 and 1902. A second trench 60 km west of Agsu was excavated near Goychay also revealing evidence of at least one event that occurred 334–118 BC. Holocene shortening and dip-slip rates for the Kura fold-thrust belt are ∼8.0 and 8.5 mm/yr, respectively, based on an uplifted strath terrace west of Agsu. The only known historical devastating (M > ∼7) earthquakes in the Kura region, west of Shamakhi, occurred in 1139 and possibly 1668. The lack of reported historical ruptures from the past 4–8 centuries in the Kura, in contrast with the numerous recorded destructive earthquakes in Shamakhi, suggests that the Kura fold-thrust belt may have accumulated sufficient strain to produce a M > 7.7 earthquake.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"79 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Diverse Structural Styles of the Northeastern Tethyan Himalaya in Southern Tibet Reveal the Early Collisional Tectonics of India and Asia 藏南喜马拉雅山东北部多样的构造样式揭示了印度和亚洲早期的碰撞构造运动

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-03-07 DOI: 10.1029/2023tc007954

Yu Tang, Xiao Liang, Genhou Wang, Dian Li, Zhanhui Qing, Yipeng Feng, Wei Zhang, Ning Han, Yang Tian, Zhuosheng Wang

{"title":"Diverse Structural Styles of the Northeastern Tethyan Himalaya in Southern Tibet Reveal the Early Collisional Tectonics of India and Asia","authors":"Yu Tang, Xiao Liang, Genhou Wang, Dian Li, Zhanhui Qing, Yipeng Feng, Wei Zhang, Ning Han, Yang Tian, Zhuosheng Wang","doi":"10.1029/2023tc007954","DOIUrl":"https://doi.org/10.1029/2023tc007954","url":null,"abstract":"The poor understanding of the structural history of the Late Triassic flysch in the northeastern Tethyan Himalaya has caused many disputes regarding India-Asia collisional tectonics. Here, we conducted an integrated study including tectonostratigraphic analysis, structural analysis, and zircon U‒Pb and muscovite 40Ar/39Ar dating to unravel the structural evolution of the Late Triassic flysch. Field geological mapping revealed that the flysch can be subdivided into three structural units, including the Gyaca mélange, Qiongjie-Dengmu shear zone and Langjiexue fold-thrust belt. The three units all contain voluminous siliciclastic rocks deposited in an abyssal submarine fan environment at the Indian passive continental margin. The Gyaca mélange shows a two-stage deformation process that generated a collisional mélange resulting from the subduction of the Indian passive continental margin. 40Ar/39Ar dating of top-to-the-south shear bands and block-in-matrix structure indicate that the India-Asia collision happened no later than the Selandian (ca. 60 Ma). The divergent imbricated thrusting and folding of the Gyaca mélange and Langjiexue fold-thrust belt formed a positive flower structure. The zircon U‒Pb and 40Ar/39Ar dating of syntectonic dikes and sericite flakes within the Gyaca mélange yield ages of ca. 56–55 Ma for the genesis of the divergent structures. Moreover, the Qiongjie-Dengmu dextral shear zone yields a sericite 40Ar/39Ar age of ca. 35 Ma and thus indicates a transient strike-slip stress regime. Generally, the early India-Asia collision tectonics in the northeastern Tethyan Himalaya showed episodic evolution with changing structural styles from mélange formation to imbricate fold-thrust belt development and finally strike-slip shear generation.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"56 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140071957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0