Tectonics最新文献_第3页

Cenozoic Pulsed Rise and Growth of the Chinese South Tianshan Revealed by Zircon and Apatite Provenance Analyses: Implications for Stepwise Aridification in the Tarim Basin 锆石和磷灰石产状分析揭示的中国南天山新生代脉冲式上升和增长：塔里木盆地逐步干旱化的影响

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-08-02 DOI: 10.1029/2023tc008211

Dunfeng Xiang, Zhiyong Zhang, David Chew, Marc Jolivet, Marco G. Malusà, Thomas Zack, Lin Wu, Chao Guo, Nan Wang, Wenjiao Xiao

{"title":"Cenozoic Pulsed Rise and Growth of the Chinese South Tianshan Revealed by Zircon and Apatite Provenance Analyses: Implications for Stepwise Aridification in the Tarim Basin","authors":"Dunfeng Xiang, Zhiyong Zhang, David Chew, Marc Jolivet, Marco G. Malusà, Thomas Zack, Lin Wu, Chao Guo, Nan Wang, Wenjiao Xiao","doi":"10.1029/2023tc008211","DOIUrl":"https://doi.org/10.1029/2023tc008211","url":null,"abstract":"Cenozoic uplift in the Tianshan played an important role in driving Proto-Paratethys Sea retreat and Asian aridification. However, most paleoclimate studies have focused on the Pamir-Tianshan corridor, and frequently overlook the role of the entire Tianshan range in modifying the Central Asian climate during Cenozoic uplift. When and how Cenozoic deformation of Tianshan was initiated and propagated are intensively debated which makes its role in contributing to climate change in Central Asia more ambiguous. To address this issue, this study presents new detrital zircon U-Pb and detrital apatite U-Pb and fission track age data from Cenozoic sedimentary successions (54–0 Ma) in the northern margin of the Tarim Basin and integrates these data with published provenance data from adjacent regions. Our results show that deformation/uplift of the Baicheng-Kuqa Depression and the South Tianshan occurred at ∼41–37 Ma and ∼24 Ma, when topographic growth of South Tianshan began to block the flow of sediment from the north. Continued uplift of the South Tianshan completely blocked fluvial transport from the Central Tianshan-Yili Block by ∼10 Ma, as shown by the paucity of 380–310 Ma detrital zircons/apatites. Far-field, north-directed compressive stress resulting from the India-Asia collision began to propagate toward the South Tianshan and its foreland during the Late Eocene, and continued to propagate into the South Tianshan and northward at the ∼24 Ma and 10 Ma. Finally, we suggest a two-stage of aridification in the Tarim Basin which can be linked to two stages (∼24 and 10 Ma) of growth of the Tianshan.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"47 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884574","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 Role of Lower Crustal Rheology on Surface Deformation During Oblique Extension: Insights From Sandbox Modeling 下地壳流变对斜向延伸过程中地表变形的作用：沙箱建模的启示

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-08-02 DOI: 10.1029/2024tc008365

Yuqiong Mao, Yiquan Li, Dong Jia, Xianyan Wang, Yingying Chen, Qin Li, Rui Li

{"title":"The Role of Lower Crustal Rheology on Surface Deformation During Oblique Extension: Insights From Sandbox Modeling","authors":"Yuqiong Mao, Yiquan Li, Dong Jia, Xianyan Wang, Yingying Chen, Qin Li, Rui Li","doi":"10.1029/2024tc008365","DOIUrl":"https://doi.org/10.1029/2024tc008365","url":null,"abstract":"Extensive researches have been conducted on the relationship between surface deformation and the properties of upper crust. However, the link between surface deformation and lower crustal rheology, especially in a three-dimensional context, remains unclear. In this study, we utilize sandbox modeling to investigate the impact of lower crustal rheology on surface deformation during oblique extension. Under the same conditions, six models with different lower crustal viscosities, both with and without syn-kinematic deposits, are conducted. The results indicate that a decrease in lower crustal viscosity may contribute to an increase in: (a) graben width, (b) graben length, (c) graben spacing, (d) the number of isolated rifts and (e) topographic relief of oblique extensional systems, while also leading to a reduction in the total number of grabens. Notably, there exists a negative linear correlation between graben spacing and lower crustal viscosity. In map view, the angle between fault strike and the direction of pre-existing discontinuities increases as the viscosity of the lower crust decreases. Furthermore, the frequency of large rakes (>50°) decreases with decreasing lower crustal viscosity. These findings align with natural examples such as the East African Rift System, Weihe Graben and the South Tibetan Rift in terms of geomorphology, tectonics, and crustal rheology. Through a comprehensive comparison of the graben width, spacing, and the angle between fault strike and the direction of pre-existing discontinuities, our study provides valuable insights into the rheology of the lower crust in natural settings.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"17 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884576","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

Transient Aseismic Vertical Deformation Across the Steeply-Dipping Pisia-Skinos Normal Fault (Gulf of Corinth, Greece) 穿越陡倾皮西亚-斯基诺斯正断层的瞬态地震垂直变形（希腊科林斯湾）

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-08-02 DOI: 10.1029/2024tc008276

Zoë K. Mildon, Manuel Diercks, Gerald P. Roberts, Joanna P. Faure Walker, Athanassios Ganas, Ioannis Papanikolaou, Vassilis Sakas, Jenni Robertson, Claudia Sgambato, Sam Mitchell

{"title":"Transient Aseismic Vertical Deformation Across the Steeply-Dipping Pisia-Skinos Normal Fault (Gulf of Corinth, Greece)","authors":"Zoë K. Mildon, Manuel Diercks, Gerald P. Roberts, Joanna P. Faure Walker, Athanassios Ganas, Ioannis Papanikolaou, Vassilis Sakas, Jenni Robertson, Claudia Sgambato, Sam Mitchell","doi":"10.1029/2024tc008276","DOIUrl":"https://doi.org/10.1029/2024tc008276","url":null,"abstract":"Geodetically-derived deformation rates are sometimes used to infer seismic hazard, implicitly assuming that short-term (annual-decadal) deformation is representative of longer-term deformation. This is despite geological observations indicating that deformation/slip rates are variable over a range of timescales. Using geodetic data from 2016 to 2021, we observe an up to 7-fold increase in vertical deformation rate in mid-2019 across the Pisia-Skinos normal fault in Greece. We hypothesize that this deformation is aseismic as there is no temporally correlated increase in the earthquake activity (M > 1). We explore four possible physical mechanisms, and our preferred hypothesis is that the transient deformation is caused by centimeter-scale slip in the upper 5 km of the Pisia fault zone. This is the first observation of shallow tectonic (i.e., not related to human activities) aseismic deformation on a normal fault globally. Our results suggest that continental normal faults can exhibit variable deformation over shorter timescales than previously observed, and thus care should be taken when utilizing geodetic rates to quantify seismic hazard.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"75 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884575","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

Magmatism and Polyphase Deformation in the Middle Jurassic Arc of Central Chile: Implications for the Tectonic Development of the Early Andean Margin 智利中部中侏罗世弧的岩浆活动和多相变形：早期安第斯边缘构造发展的影响

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-31 DOI: 10.1029/2023tc008241

John S. Singleton, Gloria Arancibia, Diego Morata, Ignacia Pérez De La Maza

{"title":"Magmatism and Polyphase Deformation in the Middle Jurassic Arc of Central Chile: Implications for the Tectonic Development of the Early Andean Margin","authors":"John S. Singleton, Gloria Arancibia, Diego Morata, Ignacia Pérez De La Maza","doi":"10.1029/2023tc008241","DOIUrl":"https://doi.org/10.1029/2023tc008241","url":null,"abstract":"The ∼173–164 Ma Papudo-Quintero plutonic complex near 32.5°S in central Chile records three deformation events that provide insight into the tectonic development of the early Andean margin. The first event (D1) includes: (a) high-temperature (>600°C), coaxial-dominated strain along NE- to N-striking subvertical shear zones; (b) widespread emplacement of granitic dikes that dip gently to steeply NE; and (c) development of narrow (<10 cm thick) strike-slip and oblique-reverse shear zones. These D1 structures record NW-SE to WNW-ESE transpressional shortening with a component of sinistral shear parallel to the N-S trending magmatic arc. Zircon and apatite U-Pb dates and cross-cutting relations constrain most D1 deformation to ∼166–164 Ma. The second event (D2) occurred during postmagmatic cooling in the Late Jurassic and was characterized by development of pervasive E-W-striking veins with alteration halos and minor strike-slip and normal faults that record N-S extension in a transtensional regime. Structures associated with the last deformation event (D3) include Late Jurassic to Early Cretaceous mafic dikes, veins, and conjugate strike-slip faults that record NW-SE to N-S shortening in a strike-slip regime. D1 deformation is consistent with studies from other areas that document NW-SE shortening ± sinistral transpression along the arc throughout the Jurassic, suggesting this deformation was regional in scale and driven by oblique subduction convergence. Deformation associated with oblique convergence was localized within the active magmatic arc, which was an important process in the early Andean orogeny. As the arc migrated eastward, D2 and D3 structures formed in a low-stress regime in an arc margin or forearc setting.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"217 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141884577","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

3D Structure of Low-Angle Normal Faults and Tectono-Sedimentary Processes of Nascent Continental Core-Complexes in the SE South China Sea 中国南海东南部低角度正断层的三维结构与新生大陆核心复合体的构造沉积过程

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-29 DOI: 10.1029/2023tc008218

E. Legeay, G. Mohn, J. C. Ringenbach, W. Vetel, F. Sapin

{"title":"3D Structure of Low-Angle Normal Faults and Tectono-Sedimentary Processes of Nascent Continental Core-Complexes in the SE South China Sea","authors":"E. Legeay, G. Mohn, J. C. Ringenbach, W. Vetel, F. Sapin","doi":"10.1029/2023tc008218","DOIUrl":"https://doi.org/10.1029/2023tc008218","url":null,"abstract":"This contribution explores the formation and evolution of hyper-extended basins, associated with the early stage of core complex formation, controlled by low-angle normal faults active at <30°. Based on a high-resolution industrial 3D seismic reflection survey along the southern margin of the South China Sea (SCS) (Dangerous Grounds), we mapped and analyzed the 3D geometry of low-angle normal fault systems and the related stratigraphy. Two main hyper-extended basins were documented, filled by up to 6 km of sediments including pre- to post-rift sequences. The observed normal faults on depth migrated seismic sections show an average dip angle of <30° and appear planar, characterized by continuous reflections with no clear steepening at depth and sole-out on distinct decollement levels. Detailed fault surface mapping reveals the occurrence of km-scale corrugations together with large wavelength undulation. The formation of these hyper-extended basins is associated with polyphased syn-rift infill during the development of the low-angle normal faults. The first syn-rift sequence appears as chaotic and discontinuous packages that has been dismembered and fragmented during the activity of low-angle normal faults. The second syn-rift package shows unexpected sedimentary wedges developing successively toward the footwall and the hangingwall. This geometry results from the interplay between the main low-angle normal fault and antithetic faults defining a so-called extensional fishtail. The deep structure of these basins shows nascent domes with limited evidence of magmatism. Eventually, these basins likely capture the earliest stage of core complex development in the proximal margin of the southern SCS.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"2 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141871517","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

Post-Collisional Reorganisation of the Eastern Alps in 4D – Crust and Mantle Structure 东阿尔卑斯山碰撞后的四维重组--地壳和地幔结构

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-28 DOI: 10.1029/2024tc008374

Peter J. McPhee, Mark R. Handy

{"title":"Post-Collisional Reorganisation of the Eastern Alps in 4D – Crust and Mantle Structure","authors":"Peter J. McPhee, Mark R. Handy","doi":"10.1029/2024tc008374","DOIUrl":"https://doi.org/10.1029/2024tc008374","url":null,"abstract":"The Eastern Alps were affected by a profound post-collisional tectonic reorganisation in Neogene time, featuring indentation by the Adriatic upper plate, rapid uplift and filling of the eastern Molasse Basin, exhumation and eastward orogen-parallel transport of Paleogene metamorphic units in the orogenic core, and a shift from northward thrust propagation in the European plate to southward propagation in the Adriatic plate. We test the idea that these events were triggered by slab detachment by reconstructing the indentation process. This involves sequentially restoring N-S and E-W cross-sections of the orogenic wedge and correcting for out-of-section orogen-parallel transport with a map-view reconstruction. We propose two phases of indentation: Initially (23 and 14 Ma), the whole Adriatic crust acted as an indenter. Its northward motion was accommodated by upright folding and orogen-parallel extensional exhumation in the Tauern Window. This phase was followed (14 Ma to Present) by continued orogen-parallel transport of the orogenic wedge into the Pannonian Basin and deformation of the leading edge of the Adriatic indenter, forming the Southern Alps fold-thrust belt. The lower crust of the Southern Alps indented the base of the Venediger Nappes in the Tauern Window, forming a high-velocity (6.8–7.25 km/s) ridge in map view at 30–45 km depth. By correlating the post-23 Ma orogenic evolution with presently imaged European slab segments in P-wave teleseismic tomography, we discern two possible Neogene slab removal events: One from 23 to 19 Ma triggering tectonic reorganisation of the Eastern Alps and its foreland basin, and potentially a second event after 14 Ma.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"78 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141871516","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

Geodynamic and Climatic Forcing on Late-Cenozoic Exhumation of the Southern Patagonian Andes (Fitz Roy and Torres del Paine massifs) 南巴塔哥尼亚安第斯山脉（菲茨-罗伊和托雷斯-德尔-潘恩山丘）晚新生代侵蚀的地球动力和气候作用力

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-23 DOI: 10.1029/2023tc007914

Veleda A. P. Muller, Christian Sue, Pierre G. Valla, Pietro Sternai, Thibaud Simon-Labric, Cécile Gautheron, Kurt M. Cuffey, Djordje Grujic, Matthias Bernet, Joseph Martinod, Matias C. Ghiglione, Peter Reiners, Chelsea Willett, David Shuster, Frédéric Herman, Lukas Baumgartner, Jean Braun

{"title":"Geodynamic and Climatic Forcing on Late-Cenozoic Exhumation of the Southern Patagonian Andes (Fitz Roy and Torres del Paine massifs)","authors":"Veleda A. P. Muller, Christian Sue, Pierre G. Valla, Pietro Sternai, Thibaud Simon-Labric, Cécile Gautheron, Kurt M. Cuffey, Djordje Grujic, Matthias Bernet, Joseph Martinod, Matias C. Ghiglione, Peter Reiners, Chelsea Willett, David Shuster, Frédéric Herman, Lukas Baumgartner, Jean Braun","doi":"10.1029/2023tc007914","DOIUrl":"https://doi.org/10.1029/2023tc007914","url":null,"abstract":"High-relief glacial valleys shape the modern topography of the Southern Patagonian Andes, but their formation remains poorly understood. Two Miocene plutonic complexes in the Andean retroarc, the Fitz Roy (49°S) and Torres del Paine (51°S) massifs, were emplaced between 16.9–16.4 Ma and 12.6–12.4 Ma, respectively. Subduction of oceanic ridge segments initiated ca. 16 Ma at 54°S, leading to northward opening of a slab window with associated mantle upwelling. The onset of major glaciations caused drastic topographic changes since ca. 7 Ma. To constrain the respective contributions of tectonic-mantle dynamics and fluvio-glacial erosion to rock exhumation and landscape evolution, we perform inverse thermal modeling of a new data set of zircon and apatite (U-Th)/He from the two massifs, complemented by apatite 4He/3He data for Torres del Paine. Our results show rapid rock exhumation recorded only in the Fitz Roy massif between 10 and 8 Ma, which we ascribe to local mantle upwelling forcing surface uplift and intensified erosion around 49°S. Both massifs record a pulse of rock exhumation between 7 and 4 Ma, which we interpret as enhanced erosion during the beginning of Patagonian glaciations. After a period of erosional and tectonic quiescence in the Pliocene, increased rock exhumation since 3–2 Ma is interpreted as the result of alpine glacial valley carving promoted by reinforced glacial-interglacial cycles. This study highlights that glacial erosion was the main driver to rock exhumation in the Patagonian retroarc since 7 Ma, but that mantle upwelling might be a driving force to rock exhumation as well.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"19 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141780107","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 Tectonic Structure and Evolution of the Potiguar-Ceará Rifted Margin of Brazil 巴西波蒂瓜尔-卡拉裂谷边缘的构造和演化

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-22 DOI: 10.1029/2023tc008184

Julia C. Fonseca, Cesar R. Ranero, Paola Vannucchi, David Iacopini, Helenice Vital

{"title":"The Tectonic Structure and Evolution of the Potiguar-Ceará Rifted Margin of Brazil","authors":"Julia C. Fonseca, Cesar R. Ranero, Paola Vannucchi, David Iacopini, Helenice Vital","doi":"10.1029/2023tc008184","DOIUrl":"https://doi.org/10.1029/2023tc008184","url":null,"abstract":"The Brazilian Equatorial Margin (BEM) is interpreted as a transform margin, where the last segment opened during Gondwana rifting. However, margin evolution, and break-up age remain unconstrained. We interpret >10k km of crustal-scale seismic images extending along ∼600 km of the margin calibrated with drillholes. We determine the style and timing of tectonics across the rift system. We link changes in crustal-scale structure and age of sediment deposits to interpret variations with the style of extension and intensity of thinning across the BEM. Observations support a rift evolution where deformation is initially distributed forming a shallow basin, subsequently focusses, and later migrates basin-ward forming the deep-water domain. We interpret that tectonic activity started ∼140–136 Ma and stopped earlier in the shallow basin causing minor thinning, than in the deep-water domain with a ∼60 km wide area with 4–8 km thick crust extended in Late Aptian to Early Albian (116–110 Ma). Constraints from seismic and drilling help define an abrupt continent to ocean transition (COT) where continental crust may be abutted by oceanic crust, and breakup occurred at early Albian time. Basin sedimentation from the onset to the Late Aptian is continental, indicating an isolated environment disconnected from Atlantic oceans. During late-most Aptian to Early Albian basin sedimentation changes and indicates a comparatively rapid marine water infill. Rifting of the BEM is not dominated by transcurrent deformation as previously inferred, with strike-slip faulting limited to comparatively small sectors, whereas most of the margin extended by normal faulting deformation.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"8 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141780182","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

Structural Variation Along the Southern Hikurangi Subduction Zone, Aotearoa New Zealand, From Seismic Reflection and Retro-Deformation Analysis 从地震反射和逆变形分析看新西兰奥特亚罗瓦南 Hikurangi 俯冲带的构造变化

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-17 DOI: 10.1029/2023tc008212

D. E. Stevens, Y. L. C. McNeill, T. J. Henstock, P. M. Barnes, G. Crutchley, N. Bangs, S. Henrys, H. J. A. Van Avendonk

{"title":"Structural Variation Along the Southern Hikurangi Subduction Zone, Aotearoa New Zealand, From Seismic Reflection and Retro-Deformation Analysis","authors":"D. E. Stevens, Y. L. C. McNeill, T. J. Henstock, P. M. Barnes, G. Crutchley, N. Bangs, S. Henrys, H. J. A. Van Avendonk","doi":"10.1029/2023tc008212","DOIUrl":"https://doi.org/10.1029/2023tc008212","url":null,"abstract":"The southern Hikurangi subduction zone exhibits significant along-strike variation in convergence rate and obliquity, sediment thickness and, uniquely, the increasing proximity of southern Hikurangi to, and impingement on, the incoming continental Chatham Rise, an ancient Gondwana accretionary complex. There are corresponding changes in the morphology and structure of the Hikurangi accretionary prism. We combine widely spaced multichannel seismic reflection profiles with high resolution bathymetry and previous interpretations to characterize the structure and the history of the accretionary prism since 2 Ma. The southern Hikurangi margin can be divided into three segments. A northeastern segment (A) characterized by a moderately wide (∼70 km), low taper (∼5°) prism recording uninhibited outward growth in the last ∼1 Myr. Deformation resolvable in seismic reflection data accounts for ∼20 % of plate convergence, comparable with the central Hikurangi margin further North. A central segment (B) characterized by a narrow (∼30 km), moderate taper (∼8°) prism, with earlier (∼2-∼1 Ma) shortening than segment A. Outward prism growth ceased coincidentally with development of major strike-slip faults in the prism interior, reduced margin-normal convergence rate, and the onset of impingement on the incoming Chatham Rise to the south. A southwestern segment (C) marks the approximate southern termination of subduction but widens to ∼50 km due to rapid outward migration of the deformation front via fault reactivation within the now-underthrusting corner of the Chatham Rise. Segment C exhibits minimal shortening as margin-normal subduction velocity decreases and plate motion is increasingly taken up by interior thrusts and strike-slip faults.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"11 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141746370","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

Slab Tear of Subducted Indian Lithosphere Beneath the Eastern Himalayan Syntaxis Region 东喜马拉雅同轴区下方俯冲印度岩石圈的板块撕裂

IF 4.2 1区地球科学

Tectonics Pub Date : 2024-07-11 DOI: 10.1029/2024tc008248

Ziqing Li, Bo Zhang, Lei Guo, Zhaoliang Hou, Bernhard Grasemann, Fulong Cai, Houqi Wang

{"title":"Slab Tear of Subducted Indian Lithosphere Beneath the Eastern Himalayan Syntaxis Region","authors":"Ziqing Li, Bo Zhang, Lei Guo, Zhaoliang Hou, Bernhard Grasemann, Fulong Cai, Houqi Wang","doi":"10.1029/2024tc008248","DOIUrl":"https://doi.org/10.1029/2024tc008248","url":null,"abstract":"In the southeastern Tibetan Plateau, region-scale dextral strike-slip shear zones, crucial for India-Asia convergence, were investigated along the Dulongjiang shear zone near the Eastern Himalayan Syntaxis (EHS). Structural, kinematic, and geochronological data from Dulongjiang and Nabang regions in western Yunnan, China, reveal dextral strike-slip shearing between 30 and 15 Ma. Various rocks were affected by moderate-temperature shear deformation (∼450–550°C), inferred from microstructures and quartz CPO patterns, during dextral strike-slip and exhumation of the shear zone. Combined with structures of pre-, syn-, and post-shearing leucogranites, zircon U-Pb dating indicates that the dextral shear along the shear zone began in the Early Oligocene (30–29 Ma) subsequent to the India-Asia collision. Micas in mylonitic granites yield 40Ar/39Ar ages, suggesting that the principal dextral shear deformation occurred approximately between 18 and 15 Ma. The Dulongjiang shear zone is linked to the Parlung, Nabang shear zone, and Sagaing Fault, forming a regional Cenozoic dextral shear system around the EHS. The study, combined with tomographic anomalies beneath the India-Asia collision zone, highlights distinct lithospheric-scale evolution in southeastern and eastern Tibet. Continuous intracontinental strike-slip shearing indicates a tectonic shift from Tibetan extension to block rotation around the EHS. From 30 to 15 Ma, slab tear, accompanied by clockwise rotation and dextral strike-slip shearing, suggests a warmer geodynamic setting influenced by hot mantle flow associated with ongoing subduction of the Indian lithosphere. Oligocene-Miocene dextral strike-slip shearing around the EHS, linking southwards with the Sagaing Fault, may correspond to the rotation necessary for slab to bend, stretch, and eventually tear beneath the region.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"29 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141613725","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