F. Feriozzi, L. Improta, F. E. Maesano, P. De Gori, R. Basili
We present the first 3D crustal model of the epicentral region of the 1980, Mw 6.9, normal-faulting Irpinia earthquake (southern Italy) determined by jointly interpreting the CROP-04 deep seismic profile, a grid of commercial seismic lines, deep exploration wells, and a high-resolution Local Earthquake Tomography. Despite numerous seismotectonic surveys and source studies of the background seismicity recorded by dense networks, a complete 3D geological model of the mid-upper crust was still lacking in the region. The architecture of the Neogene fold-and-thrust belt is also debated, with competing thin- and thick-skinned tectonic interpretations. We use the 3D geological model derived from subsurface exploration data to interpret the upper crustal tomographic velocities in terms of rock physical properties, while Vp and Vp/Vs anomalies provide inferences on the deep structural setting down to 12 km depth. We find that a thick-skinned deformation style allows explaining the geometry of Pliocene fold-and-thrust systems deforming the Apulian carbonates but also deeper Permo-Triassic metasediments and the Paleozoic crystalline femic basement. Inherited compressional structures and lithological heterogeneities control background seismicity occurring at two crustal levels. Fluid-driven shallow seismicity (<4–6 km) concentrates in a high-Vp/Vs wedge of fractured, brine-saturated Mesozoic stiff rocks delimited by the 1980 earthquake faults. Deep seismicity (9–14 km) clusters instead within the low-Vp/Vs crystalline basement underneath the Apulian carbonate ramp-anticlines. Commercial seismic data allow us to identify the Irpinia Fault, the main fault ruptured by the 1980 earthquake, reinforcing its previous interpretations as an immature structure with subtle geological and geophysical evidence.
{"title":"The 3D Crustal Structure in the Epicentral Region of the 1980, Mw 6.9, Southern Apennines Earthquake (Southern Italy): New Constraints From the Integration of Seismic Exploration Data, Deep Wells, and Local Earthquake Tomography","authors":"F. Feriozzi, L. Improta, F. E. Maesano, P. De Gori, R. Basili","doi":"10.1029/2023tc008056","DOIUrl":"https://doi.org/10.1029/2023tc008056","url":null,"abstract":"We present the first 3D crustal model of the epicentral region of the 1980, <i>M</i><sub>w</sub> 6.9, normal-faulting Irpinia earthquake (southern Italy) determined by jointly interpreting the CROP-04 deep seismic profile, a grid of commercial seismic lines, deep exploration wells, and a high-resolution Local Earthquake Tomography. Despite numerous seismotectonic surveys and source studies of the background seismicity recorded by dense networks, a complete 3D geological model of the mid-upper crust was still lacking in the region. The architecture of the Neogene fold-and-thrust belt is also debated, with competing thin- and thick-skinned tectonic interpretations. We use the 3D geological model derived from subsurface exploration data to interpret the upper crustal tomographic velocities in terms of rock physical properties, while <i>V</i><sub>p</sub> and <i>V</i><sub>p</sub>/<i>V</i><sub>s</sub> anomalies provide inferences on the deep structural setting down to 12 km depth. We find that a thick-skinned deformation style allows explaining the geometry of Pliocene fold-and-thrust systems deforming the Apulian carbonates but also deeper Permo-Triassic metasediments and the Paleozoic crystalline femic basement. Inherited compressional structures and lithological heterogeneities control background seismicity occurring at two crustal levels. Fluid-driven shallow seismicity (<4–6 km) concentrates in a high-<i>V</i><sub>p</sub>/<i>V</i><sub>s</sub> wedge of fractured, brine-saturated Mesozoic stiff rocks delimited by the 1980 earthquake faults. Deep seismicity (9–14 km) clusters instead within the low-<i>V</i><sub>p</sub>/<i>V</i><sub>s</sub> crystalline basement underneath the Apulian carbonate ramp-anticlines. Commercial seismic data allow us to identify the Irpinia Fault, the main fault ruptured by the 1980 earthquake, reinforcing its previous interpretations as an immature structure with subtle geological and geophysical evidence.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"130 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932026","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}
E. A. Roots, B. M. Frieman, G. J. Hill, R. S. Smith, J. A. Craven, A. J. Calvert, D. B. Snyder
A data set consisting of 376 broadband and long-period MT measurements was used to generate the first ever 3D resistivity model of the Archean western Superior Craton. The modeled resistivity structure is compared to coincident seismic reflection data. The observed geophysical signatures are interpreted within the context of the late stages of crustal growth and cratonization of the region via the progressive accretion of terranes against the initial cratonic core. The northern-most terranes comprising the cratonic core exhibit a nearly homogenous highly resistive crust. The lower crust of the southern terranes contains largely continuous low resistivity bands which run subparallel to major terrane boundaries and corresponding fault systems. In some cases, low resistivity features are coincident with dense packages of sub-horizontal to listric reflections within the mid- to lower crust. These resistivity structures are inferred to represent preserved geoelectric signatures of late to post-orogenic magmatic pulses likely related to delamination of locally overthickened crust. Increased mantle heat flow resulted in partial melting of the lower crust and upper mantle and upward migration of CO2-rich melts and fluids through crustal weak zones corresponding to shear and/or suture zones formed during terrane amalgamation. Thermal softening of the mid- to lower crust led to orogenic collapse and reactivation of the crustal shear zones, resulting in formation and interconnection of graphitic films which were preserved within the stable craton. These results have implications for the tectono-magmatic history of the western Superior Craton, as well toward the understanding of the geodynamic regime of the Archean Earth.
利用由 376 个宽带和长周期 MT 测量数据组成的数据集，首次生成了 Archean 西部 Superior 克拉顿的三维电阻率模型。将建模的电阻率结构与重合的地震反射数据进行了比较。观测到的地球物理特征被解释为该地区地壳生长和克拉通化的后期阶段，是通过地块对最初克拉通核心的逐步增生而形成的。构成板块地核的最北部陆块呈现出近乎同质的高电阻地壳。南部地块的下部地壳包含大体连续的低电阻率带，这些低电阻率带与主要地块边界和相应的断层系统不平行。在某些情况下，低电阻率特征与中下地壳内密集的亚水平至列表反射包相吻合。据推断，这些电阻率结构代表了晚期到成因后岩浆脉冲的地电特征，很可能与局部过厚地壳的分层有关。地幔热流的增加导致下地壳和上地幔部分熔化，富含二氧化碳的熔体和流体通过地壳薄弱带向上迁移，这些薄弱带与地台汞齐化过程中形成的剪切带和/或缝合带相对应。中下地壳的热软化导致造山运动的塌陷和地壳剪切带的重新激活，从而形成了石墨膜并使其相互连接，这些石墨膜保存在稳定的克拉通内。这些结果对西部苏必利尔克拉通的构造-岩浆历史以及对了解阿基坦地球的地球动力机制具有重要意义。
{"title":"Constraints on Growth and Stabilization of the Western Superior Craton From Inversion of Magnetotelluric Data","authors":"E. A. Roots, B. M. Frieman, G. J. Hill, R. S. Smith, J. A. Craven, A. J. Calvert, D. B. Snyder","doi":"10.1029/2023tc008110","DOIUrl":"https://doi.org/10.1029/2023tc008110","url":null,"abstract":"A data set consisting of 376 broadband and long-period MT measurements was used to generate the first ever 3D resistivity model of the Archean western Superior Craton. The modeled resistivity structure is compared to coincident seismic reflection data. The observed geophysical signatures are interpreted within the context of the late stages of crustal growth and cratonization of the region via the progressive accretion of terranes against the initial cratonic core. The northern-most terranes comprising the cratonic core exhibit a nearly homogenous highly resistive crust. The lower crust of the southern terranes contains largely continuous low resistivity bands which run subparallel to major terrane boundaries and corresponding fault systems. In some cases, low resistivity features are coincident with dense packages of sub-horizontal to listric reflections within the mid- to lower crust. These resistivity structures are inferred to represent preserved geoelectric signatures of late to post-orogenic magmatic pulses likely related to delamination of locally overthickened crust. Increased mantle heat flow resulted in partial melting of the lower crust and upper mantle and upward migration of CO<sub>2</sub>-rich melts and fluids through crustal weak zones corresponding to shear and/or suture zones formed during terrane amalgamation. Thermal softening of the mid- to lower crust led to orogenic collapse and reactivation of the crustal shear zones, resulting in formation and interconnection of graphitic films which were preserved within the stable craton. These results have implications for the tectono-magmatic history of the western Superior Craton, as well toward the understanding of the geodynamic regime of the Archean Earth.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"156 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140932115","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}
Herfried Madritsch, Nathan Looser, Raphael Schneeberger, Stephan Wohlwend, Marcel Guillong, Alexander Malz
This case-study from the Jura Mountains in the foreland of the European Alps demonstrates how the coupling of subsurface analysis and U-Pb carbonate dating can provide absolute timing constraints and shortening rate estimates of fold-and-thrust belts. It is confirmed that the initial Late Cenozoic foreland deformation driving the formation of the easternmost Jura Mountains in Switzerland was predominately thin-skinned with contractional deformation largely restricted to the Mesozoic succession above a sub-horizontal basal décollement. Thereby, the localization and structural style of related deformation structures was strongly guided by the characteristics of underlying Late Paleozoic half grabens. The main thin-skinned thrust front formed at ∼12 Ma, followed by further deformation in the hinterland and locally continued foreland-directed thrust propagation. The major deformation zones exposed at surface were established at ∼8 Ma but shortening continued until at least ∼4 Ma. Thick-skinned contraction associated with the inversion of basement structures only played a subordinate role during the latest deformation phase after 8 Ma. Based on cumulative shortening values derived from balanced cross sections, our U-Pb ages of syn-tectonic calcite slickenfibres allow to estimate thin-skinned deformation rates for the easternmost Jura Mountains between ∼0.9 and ∼0.1 mm/year, decreasing toward the eastern tip of the arcuate belt. Moreover, deformation rates seemingly decreased over time with rates of initial thin-skinned thrusting being significantly higher than the later deformation north of the main thrust front. These new findings from a classical foreland setting highlight the potential of integrating U-Pb dating in regional fold-and-thrust belt investigations elsewhere.
这项来自欧洲阿尔卑斯山前缘汝拉山脉的案例研究展示了如何将地下分析和铀-铅碳酸盐测年结合起来，为褶皱-推覆带提供绝对的时间约束和缩短率估算。研究证实，推动瑞士汝拉山脉最东部形成的晚新生代前陆最初变形主要是薄层变形，收缩变形主要局限于亚水平基底解理以上的中生代演替。因此，相关变形结构的定位和构造风格在很大程度上受下伏晚古生代半地堑特征的影响。主要的薄层推力前沿形成于 ∼12 Ma，随后在腹地发生了进一步的变形，并在局部地区继续发生了前陆导向的推力传播。暴露在地表的主要变形带形成于 ∼8 Ma，但缩短作用至少持续到 ∼4 Ma。与基底结构反转相关的厚皮收缩只在 8 Ma 之后的最新变形阶段起次要作用。根据从平衡横截面得出的累积缩短值，我们从同步构造方解石纤网的U-Pb年龄推算出汝拉山脉最东部的薄层变形速率在0.9至0.1毫米/年之间，并向弧形带的东端递减。此外，变形率似乎随着时间的推移而降低，最初的薄层推力变形率明显高于主推力前沿以北的后期变形率。这些来自经典前陆环境的新发现凸显了在其他地区的区域褶皱-推覆带研究中整合铀-铅年代测定法的潜力。
{"title":"Reconstructing the Evolution of Foreland Fold-And-Thrust Belts Using U-Pb Calcite Dating: An Integrated Case-Study From the Easternmost Jura Mountains (Switzerland)","authors":"Herfried Madritsch, Nathan Looser, Raphael Schneeberger, Stephan Wohlwend, Marcel Guillong, Alexander Malz","doi":"10.1029/2023tc008181","DOIUrl":"https://doi.org/10.1029/2023tc008181","url":null,"abstract":"This case-study from the Jura Mountains in the foreland of the European Alps demonstrates how the coupling of subsurface analysis and U-Pb carbonate dating can provide absolute timing constraints and shortening rate estimates of fold-and-thrust belts. It is confirmed that the initial Late Cenozoic foreland deformation driving the formation of the easternmost Jura Mountains in Switzerland was predominately thin-skinned with contractional deformation largely restricted to the Mesozoic succession above a sub-horizontal basal décollement. Thereby, the localization and structural style of related deformation structures was strongly guided by the characteristics of underlying Late Paleozoic half grabens. The main thin-skinned thrust front formed at ∼12 Ma, followed by further deformation in the hinterland and locally continued foreland-directed thrust propagation. The major deformation zones exposed at surface were established at ∼8 Ma but shortening continued until at least ∼4 Ma. Thick-skinned contraction associated with the inversion of basement structures only played a subordinate role during the latest deformation phase after 8 Ma. Based on cumulative shortening values derived from balanced cross sections, our U-Pb ages of syn-tectonic calcite slickenfibres allow to estimate thin-skinned deformation rates for the easternmost Jura Mountains between ∼0.9 and ∼0.1 mm/year, decreasing toward the eastern tip of the arcuate belt. Moreover, deformation rates seemingly decreased over time with rates of initial thin-skinned thrusting being significantly higher than the later deformation north of the main thrust front. These new findings from a classical foreland setting highlight the potential of integrating U-Pb dating in regional fold-and-thrust belt investigations elsewhere.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"17 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140833324","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}
N. P. Sánchez, I. Coutand, M. M. Turienzo, F. O. Lebinson, V. S. Araujo, S. Bordese, G. Arzadún, L. V. Dimieri
The Agrio Fold and Thrust Belt (FTB), situated in the Southern Central Andes at 37–39°S, underwent two phases of contractional deformation: Late Cretaceous-Eocene and middle-late Miocene. Despite advances in understanding its tectonic history, many questions persist regarding the timing and activity of specific structures during these deformation phases. By combining low-temperature multi-thermochronometry, inverse thermal models and field structural data, we present a new thermal-structural history for the northern Agrio FTB. Our findings unveil an initial cooling event between approximately 85–75 Ma and 55–50 Ma, involving cooling rates of 1.1–2°C/Ma and vertical displacement rates from 0.07 to 0.12 km/Ma. This slow event, confined to the inner zone, is associated with the growth of the basement-cored Manzano anticline. Additionally, still in the inner zone of the Agrio FTB, a second and faster cooling event from ∼15–10 Ma to 0 Ma, marked by a cooling rate of 7°C/Ma and a vertical displacement rate ranging from 0.11 to 0.17 km/Ma, results from in-sequence thick-skinned thrusting at depth. In the outer zone of the FTB, only the younger cooling event from 15–10 Ma to 0 Ma is evident, with a cooling rate of 8.8°C/Ma and a vertical displacement rate ranging from ∼0.14 to 0.26 km/Ma, attributed to displacement along the basement-involved Las Yeseras thrust. Furthermore, Apatite Fission Track (AFT) ages of detrital grains in the Tralalhué conglomerates support the maximum depositional age for these synorogenic strata to be between 14.1 and 9.2 Ma.
阿格里奥褶皱和推力带（FTB）位于南纬 37-39 度的安第斯山脉中南部，经历了两个阶段的收缩变形：晚白垩世-始新世和中新世中晚期。尽管在了解其构造历史方面取得了进展，但关于这些变形阶段中特定结构的时间和活动的许多问题依然存在。通过结合低温多热时测定法、逆热模型和野外构造数据，我们展示了阿格里奥外陆桥北部新的热构造历史。我们的研究结果揭示了大约 85-75 Ma 到 55-50 Ma 之间的初始冷却事件，涉及 1.1-2°C/Ma 的冷却速率和 0.07 到 0.12 km/Ma 的垂直位移速率。这一缓慢的事件仅限于内部区域，与基底包裹的曼萨诺反斜的增长有关。此外，还是在阿格里奥远断层带的内部区域，从 15-10 Ma 到 0 Ma 发生了第二次较快的冷却事件，冷却速率为 7°C/Ma ，垂直位移速率为 0.11 至 0.17 km/Ma，这是由深部的内序厚皮推力造成的。在FTB的外部区域，只有从15-10 Ma到0 Ma的较年轻的冷却事件是明显的，冷却速率为8.8°C/Ma，垂直位移速率在0.14至0.26 km/Ma之间，这归因于沿涉及基底的Las Yeseras推力的位移。此外，Tralalhué砾岩中碎屑颗粒的磷灰石裂变轨道（AFT）年龄支持这些同生地层的最大沉积年龄在 14.1 至 9.2 Ma 之间。
{"title":"Structural Evolution of the Northern Agrio Fold and Trust Belt (∼37°30′S), Neuquén Basin, Argentina, Derived From Low-Temperature Multi-Thermochronometry","authors":"N. P. Sánchez, I. Coutand, M. M. Turienzo, F. O. Lebinson, V. S. Araujo, S. Bordese, G. Arzadún, L. V. Dimieri","doi":"10.1029/2023tc007868","DOIUrl":"https://doi.org/10.1029/2023tc007868","url":null,"abstract":"The Agrio Fold and Thrust Belt (FTB), situated in the Southern Central Andes at 37–39°S, underwent two phases of contractional deformation: Late Cretaceous-Eocene and middle-late Miocene. Despite advances in understanding its tectonic history, many questions persist regarding the timing and activity of specific structures during these deformation phases. By combining low-temperature multi-thermochronometry, inverse thermal models and field structural data, we present a new thermal-structural history for the northern Agrio FTB. Our findings unveil an initial cooling event between approximately 85–75 Ma and 55–50 Ma, involving cooling rates of 1.1–2°C/Ma and vertical displacement rates from 0.07 to 0.12 km/Ma. This slow event, confined to the inner zone, is associated with the growth of the basement-cored Manzano anticline. Additionally, still in the inner zone of the Agrio FTB, a second and faster cooling event from ∼15–10 Ma to 0 Ma, marked by a cooling rate of 7°C/Ma and a vertical displacement rate ranging from 0.11 to 0.17 km/Ma, results from in-sequence thick-skinned thrusting at depth. In the outer zone of the FTB, only the younger cooling event from 15–10 Ma to 0 Ma is evident, with a cooling rate of 8.8°C/Ma and a vertical displacement rate ranging from ∼0.14 to 0.26 km/Ma, attributed to displacement along the basement-involved Las Yeseras thrust. Furthermore, Apatite Fission Track (AFT) ages of detrital grains in the Tralalhué conglomerates support the maximum depositional age for these synorogenic strata to be between 14.1 and 9.2 Ma.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"72 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140808846","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}
R. Dawood, A. Matmon, L. Benedetti, , S. Siman-Tov
Recovering the seismic history of multiple segments within a fault system provides a spatiotemporal framework for the fault activity across the system. This kind of data is essential for improving our understanding of how faults interact during earthquake cycles and how they are distributed within a fault system. Bedrock fault scarps, reaching up to 10-m height, are abundant across the Bet Kerem fault system, Galilee, northern Israel. Using the 36Cl exposure dating method, we recovered the last 30 ka scarp exhumation history of three fault segments from the Bet Kerem fault system. Results indicate that the three faults were active simultaneously in at least three distinguished activity periods, during which a minimum of 1.2 m of surface rupturing occurred in each period. The synchronized activity and total surface rupture at each activity period suggest that the three dated segments were ruptured simultaneously by the same earthquake. That is, a multi-segment rupture earthquake and that each activity period included a cluster of at least two large multi-segment earthquakes. The results also indicate a recurrence interval between clusters of 3.5–4.5 ka and the existence of a seismic super cycle with a recurrence interval of about 13 ka.
恢复断层系统中多个区段的地震历史为整个系统的断层活动提供了时空框架。这类数据对于我们更好地了解断层在地震周期中的相互作用以及断层在断层系统中的分布情况至关重要。在以色列北部加利利的 Bet Kerem 断层系统中，有大量高达 10 米的基岩断层疤痕。利用 36Cl 暴露年代测定法，我们复原了 Bet Kerem 断层系统中三个断层段最近 30 ka 年的疤痕隆升史。结果表明，这三个断层至少在三个不同的活动期同时活动，每个活动期至少发生 1.2 米的地表破裂。每个活动期的同步活动和地表断裂总长度表明，这三个年代分段是由同一次地震同时造成的。也就是说，这是一次多地段断裂地震，而且每个活动期都包括至少两个大型多地段地震群。结果还表明，地震群之间的重现间隔为 3.5-4.5 ka，存在一个重现间隔约为 13 ka 的地震超级周期。
{"title":"Multi-Segment Earthquake Clustering as Inferred From 36Cl Exposure Dating, the Bet Kerem Fault System, Northern Israel","authors":"R. Dawood, A. Matmon, L. Benedetti, , S. Siman-Tov","doi":"10.1029/2023tc007953","DOIUrl":"https://doi.org/10.1029/2023tc007953","url":null,"abstract":"Recovering the seismic history of multiple segments within a fault system provides a spatiotemporal framework for the fault activity across the system. This kind of data is essential for improving our understanding of how faults interact during earthquake cycles and how they are distributed within a fault system. Bedrock fault scarps, reaching up to 10-m height, are abundant across the Bet Kerem fault system, Galilee, northern Israel. Using the <sup>36</sup>Cl exposure dating method, we recovered the last 30 ka scarp exhumation history of three fault segments from the Bet Kerem fault system. Results indicate that the three faults were active simultaneously in at least three distinguished activity periods, during which a minimum of 1.2 m of surface rupturing occurred in each period. The synchronized activity and total surface rupture at each activity period suggest that the three dated segments were ruptured simultaneously by the same earthquake. That is, a multi-segment rupture earthquake and that each activity period included a cluster of at least two large multi-segment earthquakes. The results also indicate a recurrence interval between clusters of 3.5–4.5 ka and the existence of a seismic super cycle with a recurrence interval of about 13 ka.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"46 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140797769","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}
Jun Liu, Matthias Rosenau, Sascha Brune, Ehsan Kosari, Michael Rudolf, Onno Oncken
Triaxial deformation is a general feature of continental tectonics, but its controls and the systematics of associated fault networks remain poorly understood. We present triaxial analog experiments mimicking crustal thinning resulting from distributed longitudinal extension and lateral shortening. Contemporary longitudinal extension and lateral shortening are related by the principal horizontal strain ratio (PHSR). We investigate the effect of crustal geometry, rheology and strain rate on deformation localization, faulting regime and pattern, and PHSR in brittle and brittle-viscous crustal-scale models. We find that in brittle models the fault networks reflect the basal boundary condition and fault-density scales inversely with brittle layer thickness. In brittle-viscous models, as strain rate (ė) decreases, (a) Three fault patterns emerge: conjugate sets of strike-slip faults (ė > 3 × 10−4 s−1, PHSR > 0.31), sets of parallel oblique normal faults (ė = 0.3–3 × 10−4 s−1, PHSR = 0.15–0.25), horst-and-graben system (ė < 0.3 × 10−4 s−1, PHSR < 0.1). (b) The strain localization increases systematically and gradually. We interpret the strain rate dependent of faulting regimes to be controlled by vertical coupling between the model upper mantle and model upper crust resulting in spontaneous permutation of principal stress axes. Rate-dependency of strain localization can be related to mechanical coupling between the upper and lower crust. We identify the following parameters controlling triaxial tectonic deformation: upper crustal thickness and friction coefficient, lower crustal thickness and viscosity, as well as strain rate. We test our models and predictions against natural prototypes (Tibet, Anatolia, Apennines, and Basin and Range Province) thus providing new perspectives on triaxial deformation.
{"title":"Fault Networks in Triaxial Tectonic Settings: Analog Modeling of Distributed Continental Extension With Lateral Shortening","authors":"Jun Liu, Matthias Rosenau, Sascha Brune, Ehsan Kosari, Michael Rudolf, Onno Oncken","doi":"10.1029/2023tc008127","DOIUrl":"https://doi.org/10.1029/2023tc008127","url":null,"abstract":"Triaxial deformation is a general feature of continental tectonics, but its controls and the systematics of associated fault networks remain poorly understood. We present triaxial analog experiments mimicking crustal thinning resulting from distributed longitudinal extension and lateral shortening. Contemporary longitudinal extension and lateral shortening are related by the principal horizontal strain ratio (PHSR). We investigate the effect of crustal geometry, rheology and strain rate on deformation localization, faulting regime and pattern, and PHSR in brittle and brittle-viscous crustal-scale models. We find that in brittle models the fault networks reflect the basal boundary condition and fault-density scales inversely with brittle layer thickness. In brittle-viscous models, as strain rate (<i>ė</i>) decreases, (a) Three fault patterns emerge: conjugate sets of strike-slip faults (<i>ė</i> > 3 × 10<sup>−4</sup> s<sup>−1</sup>, PHSR > 0.31), sets of parallel oblique normal faults (<i>ė</i> = 0.3–3 × 10<sup>−4</sup> s<sup>−1</sup>, PHSR = 0.15–0.25), horst-and-graben system (<i>ė</i> < 0.3 × 10<sup>−4</sup> s<sup>−1</sup>, PHSR < 0.1). (b) The strain localization increases systematically and gradually. We interpret the strain rate dependent of faulting regimes to be controlled by vertical coupling between the model upper mantle and model upper crust resulting in spontaneous permutation of principal stress axes. Rate-dependency of strain localization can be related to mechanical coupling between the upper and lower crust. We identify the following parameters controlling triaxial tectonic deformation: upper crustal thickness and friction coefficient, lower crustal thickness and viscosity, as well as strain rate. We test our models and predictions against natural prototypes (Tibet, Anatolia, Apennines, and Basin and Range Province) thus providing new perspectives on triaxial deformation.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"46 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140797861","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}
Anna K. Bidgood, Andrew J. Parsons, Nick M. W. Roberts, Dave Waters, Simon Tapster, Phillip Gopon
The burial and exhumation of continental crust to and from ultrahigh-pressure (UHP) is an important orogenic process, often interpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate the timing and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We present new petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotime geochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographic observations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growth at eclogite facies conditions. Those ages overlap with zircon rim ages (48.9 ± 1.2 Ma, LA-ICP-MS) and xenotime ages (47.4 ± 1.4 Ma; LA-ICP-MS) from the hosting Puga gneiss, which grew during breakdown of UHP garnet rims. We argue that peak zircon growth at 47–46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation through the rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping ages from Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regional synthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47–46 Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightly constrained time-stamp significant geodynamic shifts within the orogen and wider plate network.
{"title":"The Geodynamic Significance of Continental UHP Exhumation: New Constraints From the Tso Morari Complex, NW Himalaya","authors":"Anna K. Bidgood, Andrew J. Parsons, Nick M. W. Roberts, Dave Waters, Simon Tapster, Phillip Gopon","doi":"10.1029/2023tc007976","DOIUrl":"https://doi.org/10.1029/2023tc007976","url":null,"abstract":"The burial and exhumation of continental crust to and from ultrahigh-pressure (UHP) is an important orogenic process, often interpreted with respect to the onset and/or subduction dynamics of continent-continent collision. Here, we investigate the timing and significance of UHP metamorphism and exhumation of the Tso Morari complex, North-West Himalaya. We present new petrochronological analyses of mafic eclogites and their host-rock gneisses, combining U-Pb zircon, rutile and xenotime geochronology (high-precision CA-ID-TIMS and high-spatial resolution LA-ICP-MS), garnet element maps, and petrographic observations. Zircon from mafic eclogite have a CA-ID-TIMS age of 46.91 ± 0.07 Ma, with REE profiles indicative of growth at eclogite facies conditions. Those ages overlap with zircon rim ages (48.9 ± 1.2 Ma, LA-ICP-MS) and xenotime ages (47.4 ± 1.4 Ma; LA-ICP-MS) from the hosting Puga gneiss, which grew during breakdown of UHP garnet rims. We argue that peak zircon growth at 47–46 Ma corresponds to the onset of exhumation from UHP conditions. Subsequent exhumation through the rutile closure temperature, is constrained by new dates of 40.4 ± 1.7 and 36.3 ± 3.8 Ma (LA-ICP-MS). Overlapping ages from Kaghan imply a coeval time-frame for the onset of UHP exhumation across the NW Himalaya. Furthermore, our regional synthesis demonstrates a causative link between changes in the subduction dynamics of the India-Asia collision zone at 47–46 Ma and the resulting mid-Eocene plate network reorganization. The onset of UHP exhumation therefore provides a tightly constrained time-stamp significant geodynamic shifts within the orogen and wider plate network.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"151 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140797776","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}
M. Ponikowska, S. M. Stovba, S. Mazur, M. Malinowski, P. Krzywiec, Q. Nguyen, C. Hübscher
The southern Baltic Sea is a peculiar area, where the Sorgenfrei-Tornquist Zone (STZ), stretching from Bornholm into the North Sea, connects to the Teisseyre-Tornquist Zone (TTZ) that continues SE up to the Black Sea. In this study, we show the structure and evolution of this controversially debated area, both on crustal and basin scale, by using three seismic reflection profiles combined with 2-D potential field data. The results demonstrate that the southern Baltic Sea is underlain by a thick crust of the East European Craton with a Moho depth in the range of 38–42 km. The overall crustal architecture is shaped by three phases of localized stretching in the early Paleozoic, Devonian-Carboniferous, and Permian-Mesozoic. The most spectacular feature of the southern Baltic Sea is a zone of thick-skinned compressional deformation produced by Late Cretaceous-early Paleogene inversion, including a system of thrusts and back thrusts penetrating the entire crust in an 80–90 km wide inversion zone. ENE-vergent thrusts are traced from the top of the Cretaceous down to the Moho and they are accompanied by back thrusts of opposite vergence, also reaching the Moho. Inversion tectonics resulted in the uplift of a block of cratonic crust as a pop-up structure, bounded by thrusts and back thrusts, and the displacement of the Moho within the STZ and TTZ. The similar mechanism of intra-cratonic inversion was recognized for the Donbas Foldbelt in eastern Ukraine, and it may be characteristic of rigid cratons, where deformation is localized in a few preexisting zones of weakness.
{"title":"Crustal-Scale Pop-Up Structure at the Junction of Two Continental-Scale Deformation Zones in the Southern Baltic Sea","authors":"M. Ponikowska, S. M. Stovba, S. Mazur, M. Malinowski, P. Krzywiec, Q. Nguyen, C. Hübscher","doi":"10.1029/2023tc008066","DOIUrl":"https://doi.org/10.1029/2023tc008066","url":null,"abstract":"The southern Baltic Sea is a peculiar area, where the Sorgenfrei-Tornquist Zone (STZ), stretching from Bornholm into the North Sea, connects to the Teisseyre-Tornquist Zone (TTZ) that continues SE up to the Black Sea. In this study, we show the structure and evolution of this controversially debated area, both on crustal and basin scale, by using three seismic reflection profiles combined with 2-D potential field data. The results demonstrate that the southern Baltic Sea is underlain by a thick crust of the East European Craton with a Moho depth in the range of 38–42 km. The overall crustal architecture is shaped by three phases of localized stretching in the early Paleozoic, Devonian-Carboniferous, and Permian-Mesozoic. The most spectacular feature of the southern Baltic Sea is a zone of thick-skinned compressional deformation produced by Late Cretaceous-early Paleogene inversion, including a system of thrusts and back thrusts penetrating the entire crust in an 80–90 km wide inversion zone. ENE-vergent thrusts are traced from the top of the Cretaceous down to the Moho and they are accompanied by back thrusts of opposite vergence, also reaching the Moho. Inversion tectonics resulted in the uplift of a block of cratonic crust as a pop-up structure, bounded by thrusts and back thrusts, and the displacement of the Moho within the STZ and TTZ. The similar mechanism of intra-cratonic inversion was recognized for the Donbas Foldbelt in eastern Ukraine, and it may be characteristic of rigid cratons, where deformation is localized in a few preexisting zones of weakness.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"31 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567395","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}
Core complex type structures are common in continental margins. Recent studies have proposed exhumation of deeper crustal and mantle levels during extension of the continental margin along the Northern South China Sea (NSCS) in a core complex mode. Here, we present high-resolution seismic profiles across different sections of the NSCS that allow us to observe two types of core complex systems. The Kaiping Rift and eastern Baiyun Rift are characterized by a sub-horizontal Moho and exhumation of ductile deeper crust beneath an extremely thinned brittle upper crust. The central Baiyun Rift in contrast is marked by homogeneous thinning of the entire crust that is floored by mantle unroofing with a concave-down Moho geometry. While the former type, referred to as crustal core complexes, coincides with relatively intense syn-rift magmatism, the latter, referred to as mantle core complexes, is marked by limited magmatism. Consistently, basin subsidence rates are lower over crustal core complexes than mantle core complexes. Compared to mantle core complexes at the magma-poor Iberian margin, the widely distributed crustal core complexes in the NSCS indicate higher geotherms and more intense magmatism during extension of the continental lithosphere. We propose that the continental core complexes observed at the NSCS represent a typical outcome of extension of a gravitationally unstable lithosphere.
{"title":"Consequences of Continental Core Complexes on Rifting Patterns: Insights From Multichannel Seismic Data From the Northern Margin of the South China Sea","authors":"Yancheng Xu, Jianye Ren, Yanghui Zhao, Jinyun Zheng, Chao Lei, Dingwei Zhu","doi":"10.1029/2023tc007870","DOIUrl":"https://doi.org/10.1029/2023tc007870","url":null,"abstract":"Core complex type structures are common in continental margins. Recent studies have proposed exhumation of deeper crustal and mantle levels during extension of the continental margin along the Northern South China Sea (NSCS) in a core complex mode. Here, we present high-resolution seismic profiles across different sections of the NSCS that allow us to observe two types of core complex systems. The Kaiping Rift and eastern Baiyun Rift are characterized by a sub-horizontal Moho and exhumation of ductile deeper crust beneath an extremely thinned brittle upper crust. The central Baiyun Rift in contrast is marked by homogeneous thinning of the entire crust that is floored by mantle unroofing with a concave-down Moho geometry. While the former type, referred to as crustal core complexes, coincides with relatively intense syn-rift magmatism, the latter, referred to as mantle core complexes, is marked by limited magmatism. Consistently, basin subsidence rates are lower over crustal core complexes than mantle core complexes. Compared to mantle core complexes at the magma-poor Iberian margin, the widely distributed crustal core complexes in the NSCS indicate higher geotherms and more intense magmatism during extension of the continental lithosphere. We propose that the continental core complexes observed at the NSCS represent a typical outcome of extension of a gravitationally unstable lithosphere.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"61 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567616","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}
Taylor Schildgen, Margaret Rusmore, Jonathan Aitchison, Laurent Jolivet
The editors of Tectonics would like to offer our sincere thanks to those who reviewed manuscripts for us in 2023. The time reviewers spend reading and commenting on manuscripts helps to ensure that our science is well communicated, clearly documented, appropriately placed in the context of prior work, and effectively archived for future usage. We understand that as one of the AGU journals hosting long format articles, reviewing a manuscript for Tectonics is a considerable time commitment. For this reason, we are particularly grateful to our reviewers for their diligence in helping to provide high-quality, timely reviews. We also appreciate the efforts many reviewers contribute toward advancing open science by evaluating the availability and accessibility of data, which are key objectives of the AGU's FAIR data policy. The 137 papers published in Tectonics in 2023 benefitted from the careful scrutiny and constructive critique drawn from the expertise of 465 reviewers, who provided a total of 652 reviews. We are grateful for this contribution toward producing the high-quality output that has helped Tectonics maintain a prominent position in scientific publishing for decades, and for the spirit of teamwork that makes the peer review process an asset in our community.
{"title":"Thank You to Our 2023 Reviewers","authors":"Taylor Schildgen, Margaret Rusmore, Jonathan Aitchison, Laurent Jolivet","doi":"10.1029/2024tc008348","DOIUrl":"https://doi.org/10.1029/2024tc008348","url":null,"abstract":"The editors of Tectonics would like to offer our sincere thanks to those who reviewed manuscripts for us in 2023. The time reviewers spend reading and commenting on manuscripts helps to ensure that our science is well communicated, clearly documented, appropriately placed in the context of prior work, and effectively archived for future usage. We understand that as one of the AGU journals hosting long format articles, reviewing a manuscript for Tectonics is a considerable time commitment. For this reason, we are particularly grateful to our reviewers for their diligence in helping to provide high-quality, timely reviews. We also appreciate the efforts many reviewers contribute toward advancing open science by evaluating the availability and accessibility of data, which are key objectives of the AGU's FAIR data policy. The 137 papers published in <i>Tectonics</i> in 2023 benefitted from the careful scrutiny and constructive critique drawn from the expertise of 465 reviewers, who provided a total of 652 reviews. We are grateful for this contribution toward producing the high-quality output that has helped <i>Tectonics</i> maintain a prominent position in scientific publishing for decades, and for the spirit of teamwork that makes the peer review process an asset in our community.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"26 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567399","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：