Fanny Goussin, Stéphane Guillot, Gilles Ruffet, Marc Poujol, Émilien Oliot, Anne Replumaz, Carole Cordier, Guillaume Dupont-Nivet, Pierrick Roperch
The Tibetan Plateau was formed by intense Cenozoic shortening (up to 1,100 km) of a composite “proto-Tibet,” itself the product of a long Paleozoic and Mesozoic history of accretion of Gondwana-derived continental fragments and volcanic arcs against the Asian continental margin. The difficult access and the scarcity of outcrops have long limited the possibilities of studying these Mesozoic suture zones in the heart of the Plateau. In this work, we present new U-Pb and 40Ar/39Ar ages from the highly deformed units of the Yushu mélange, along the Jinsha Suture in the northeastern Qiangtang terrane. Early Triassic (c. 253 Ma) to Middle Jurassic ages (c. 165 Ma) complement the existing data set and help to refine the chronology of the Paleo-Tethyan oceanic subductions which have structured the northeastern part of the Qiangtang terrane. The Yushu mélange records at least three successive tectono-magmatic events. The opening of a back-arc basin during the northward Paleo-Tethyan subduction along the Longmu Co-Shuanghu Suture during Early to Middle Triassic; then its closure during the southward subduction of the Songpan-Ganze Ocean along the Jinsha Suture in Late Triassic. Finally, a shortening phase related to the continental collision of the Songpan-Ganze and Qiangtang blocks from Late Triassic to Early-Middle Jurassic. No evidence for any high- or mid-temperature Cenozoic reactivation of the Jinsha suture in our study area is recorded.
{"title":"Polarity and Timing of the Deformation Along the Jinsha Suture Zone (Yushu Area, Northeastern Tibet)","authors":"Fanny Goussin, Stéphane Guillot, Gilles Ruffet, Marc Poujol, Émilien Oliot, Anne Replumaz, Carole Cordier, Guillaume Dupont-Nivet, Pierrick Roperch","doi":"10.1029/2023tc007888","DOIUrl":"https://doi.org/10.1029/2023tc007888","url":null,"abstract":"The Tibetan Plateau was formed by intense Cenozoic shortening (up to 1,100 km) of a composite “proto-Tibet,” itself the product of a long Paleozoic and Mesozoic history of accretion of Gondwana-derived continental fragments and volcanic arcs against the Asian continental margin. The difficult access and the scarcity of outcrops have long limited the possibilities of studying these Mesozoic suture zones in the heart of the Plateau. In this work, we present new U-Pb and <sup>40</sup>Ar/<sup>39</sup>Ar ages from the highly deformed units of the Yushu mélange, along the Jinsha Suture in the northeastern Qiangtang terrane. Early Triassic (c. 253 Ma) to Middle Jurassic ages (c. 165 Ma) complement the existing data set and help to refine the chronology of the Paleo-Tethyan oceanic subductions which have structured the northeastern part of the Qiangtang terrane. The Yushu mélange records at least three successive tectono-magmatic events. The opening of a back-arc basin during the northward Paleo-Tethyan subduction along the Longmu Co-Shuanghu Suture during Early to Middle Triassic; then its closure during the southward subduction of the Songpan-Ganze Ocean along the Jinsha Suture in Late Triassic. Finally, a shortening phase related to the continental collision of the Songpan-Ganze and Qiangtang blocks from Late Triassic to Early-Middle Jurassic. No evidence for any high- or mid-temperature Cenozoic reactivation of the Jinsha suture in our study area is recorded.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"61 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541380","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}
T. Geffroy, B. Guillaume, M. Simoes, A. Replumaz, R. Lacassin, L. Husson, J. Kermarrec
Along convergent boundaries, the role played by mantle drag remains poorly understood despite its potential impact on subduction dynamics and in turn on the deformation regime of the overriding plate. In this study, we present 11 three‐dimensional analog models of subduction including an overriding plate, in which mantle drag at the base of the lower or upper plate results from an imposed unidirectional horizontal mantle flow perpendicular to the trench, and in which the plate opposite to the flow is fixed. We varied the direction and the velocity of the imposed horizontal mantle flow between 0 and 10 cm/yr to quantify its impact on horizontal and vertical upper plate deformation, velocities of plates and subduction, and slab geometry. In our experiments, we show that a mantle flow lower than 5 cm/yr tends to laterally translate the slab rather than to generate internal deformation, resulting in limited differences in slab geometries between models. We also show that plate velocity correlates linearly with the imposed mantle flow velocity and associated mantle drag. The upper plate most often deforms by trench‐orthogonal shortening, with shortening rates increasing linearly with mantle flow. Shortening rates are higher when mantle flow is directed toward the fixed upper plate and when the slab has not yet reached the upper‐lower mantle discontinuity. Minimum trench‐orthogonal shortening rates of 2.5 × 10−15 s−1 are required to thicken upper plates. This study suggests that mantle drag can exert first‐order controls on the dynamics of subduction zones and associated tectonics.
{"title":"Role of Mantle Drag on the Tectonics of Subduction Zones: Insights From Laboratory Models","authors":"T. Geffroy, B. Guillaume, M. Simoes, A. Replumaz, R. Lacassin, L. Husson, J. Kermarrec","doi":"10.1029/2023tc008018","DOIUrl":"https://doi.org/10.1029/2023tc008018","url":null,"abstract":"Along convergent boundaries, the role played by mantle drag remains poorly understood despite its potential impact on subduction dynamics and in turn on the deformation regime of the overriding plate. In this study, we present 11 three‐dimensional analog models of subduction including an overriding plate, in which mantle drag at the base of the lower or upper plate results from an imposed unidirectional horizontal mantle flow perpendicular to the trench, and in which the plate opposite to the flow is fixed. We varied the direction and the velocity of the imposed horizontal mantle flow between 0 and 10 cm/yr to quantify its impact on horizontal and vertical upper plate deformation, velocities of plates and subduction, and slab geometry. In our experiments, we show that a mantle flow lower than 5 cm/yr tends to laterally translate the slab rather than to generate internal deformation, resulting in limited differences in slab geometries between models. We also show that plate velocity correlates linearly with the imposed mantle flow velocity and associated mantle drag. The upper plate most often deforms by trench‐orthogonal shortening, with shortening rates increasing linearly with mantle flow. Shortening rates are higher when mantle flow is directed toward the fixed upper plate and when the slab has not yet reached the upper‐lower mantle discontinuity. Minimum trench‐orthogonal shortening rates of 2.5 × 10−15 s−1 are required to thicken upper plates. This study suggests that mantle drag can exert first‐order controls on the dynamics of subduction zones and associated tectonics.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"51 18","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138993364","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}
The Cadomian Orogeny produced a subduction-related orogen along the periphery of Gondwana and configured the pre-Variscan basement of the Iberian Massif. The architecture of the Cadomian Orogen requires detailed structural analysis for reconstruction because of severe tectonic reworking during the Paleozoic (Variscan cycle). Tectonometamorphic analysis and data compilation in SW Iberia (La Serena Massif, Spain) have allowed the identification of three Cadomian deformation phases and further constrained the global architecture and large-scale processes that contributed to the Ediacaran building and early Paleozoic dismantling of the Cadomian Orogen. The first phase (DC1, prior to 573 Ma) favored tabular morphology in plutons that intruded during the building of a continental arc. The second phase (DC2, 573–535 Ma) produced an upright folding and contributed to further crustal thickening. The third phase of deformation (DC3, ranging between ∼535 and ∼480 Ma) resulted in an orogen-parallel dome with oblique extensional flow. DC1 represents the crustal growth and thickening stage. DC2 is synchronous with a period of crustal thickening that affected most of the Gondwanan periphery, from the most external sections (Cadomian fore-arc) to the inner ones (Cadomian back-arc). We explain DC2 as a consequence of flat subduction, which was followed by a period dominated by crustal extension (DC3) upon roll-back of the lower plate. The Ediacaran construction of the Cadomian Orogen (DC1 and DC2) requires ongoing subduction beneath Gondwana s.l., whereas its dismantlement during the Early Paleozoic is compatible with oblique, sinistral convergence.
{"title":"Building and Collapse of the Cadomian Orogen: A Plate-Scale Model Based on Structural Data From the SW Iberian Massif","authors":"Diana Moreno-Martín, Rubén Díez Fernández, Ricardo Arenas, Esther Rojo-Pérez, Irene Novo-Fernández, Sonia Sánchez Martínez","doi":"10.1029/2023tc007990","DOIUrl":"https://doi.org/10.1029/2023tc007990","url":null,"abstract":"The Cadomian Orogeny produced a subduction-related orogen along the periphery of Gondwana and configured the pre-Variscan basement of the Iberian Massif. The architecture of the Cadomian Orogen requires detailed structural analysis for reconstruction because of severe tectonic reworking during the Paleozoic (Variscan cycle). Tectonometamorphic analysis and data compilation in SW Iberia (La Serena Massif, Spain) have allowed the identification of three Cadomian deformation phases and further constrained the global architecture and large-scale processes that contributed to the Ediacaran building and early Paleozoic dismantling of the Cadomian Orogen. The first phase (D<sub>C1</sub>, prior to 573 Ma) favored tabular morphology in plutons that intruded during the building of a continental arc. The second phase (D<sub>C2</sub>, 573–535 Ma) produced an upright folding and contributed to further crustal thickening. The third phase of deformation (D<sub>C3</sub>, ranging between ∼535 and ∼480 Ma) resulted in an orogen-parallel dome with oblique extensional flow. D<sub>C1</sub> represents the crustal growth and thickening stage. D<sub>C2</sub> is synchronous with a period of crustal thickening that affected most of the Gondwanan periphery, from the most external sections (Cadomian fore-arc) to the inner ones (Cadomian back-arc). We explain D<sub>C2</sub> as a consequence of flat subduction, which was followed by a period dominated by crustal extension (D<sub>C3</sub>) upon roll-back of the lower plate. The Ediacaran construction of the Cadomian Orogen (D<sub>C1</sub> and D<sub>C2</sub>) requires ongoing subduction beneath Gondwana <i>s</i>.<i>l</i>., whereas its dismantlement during the Early Paleozoic is compatible with oblique, sinistral convergence.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"40 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541372","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}
Paulo Marcos, Emiliano M. Renda, Pablo D. González, Sebastián Oriolo, Nicolás Scivetti, Leonardo Benedini, Mauro Geraldes, Daniel Gregori, María Belén Yoya, Marcos Bahía
In this contribution, we present new early middle Devonian igneous and metaigneous units with a major juvenile magmatic source input in the North Patagonian Massif, which were discovered through U‐Pb and Lu‐Hf zircon analyses. Afterward, we assessed their tectonic implications for northwestern Patagonia and then for southern South America, combining our results with available database information consisting of igneous crystallization ages and isotopic data of the Devonian to early Carboniferous magmatic units, tectonic‐metamorphic analyses, and thermochronologic record. This study allows for distinguishing retreating and advancing subduction switching in northwestern Patagonia (38°30′ to 44°S) and a contrasting coetaneous evolution for basement outcrops exposed further north (27°30′ and 37°30′S). The early middle Devonian (400–380 Ma) northwestern Patagonian magmatism is characterized by widespread magmatism and positive εHf–εNd linked to forearc and backarc magmatism that evolved within a retreating subduction stage. A tectonic switching toward advancing orogeny stage began in the late Devonian, evidenced by a lull in magmatic activity with a negative εHf–εNd trend, possibly contemporaneous with the first tectonic‐metamorphic event in western Patagonia. An early Carboniferous magmatic gap, followed by the subsequent development of the main foliation in the basement during the Carboniferous‐Permian period, denotes the acme of this contractional stage. In contrast, the Devonian period in the northern segment is characterized by mostly negative εHf–εNd values, reverse shear zone activity in the foreland, and an inboard magmatism migration, evidencing a compressive tectonic setting that changed to an extensional configuration in the early Carboniferous with widespread arc magmatism development.
{"title":"Devonian to Early Carboniferous Retreating—Advancing Subduction Switch in the Northwestern Patagonia Accretionary Orogen: U-Pb and Lu-Hf Isotopic Insights","authors":"Paulo Marcos, Emiliano M. Renda, Pablo D. González, Sebastián Oriolo, Nicolás Scivetti, Leonardo Benedini, Mauro Geraldes, Daniel Gregori, María Belén Yoya, Marcos Bahía","doi":"10.1029/2022tc007533","DOIUrl":"https://doi.org/10.1029/2022tc007533","url":null,"abstract":"In this contribution, we present new early middle Devonian igneous and metaigneous units with a major juvenile magmatic source input in the North Patagonian Massif, which were discovered through U‐Pb and Lu‐Hf zircon analyses. Afterward, we assessed their tectonic implications for northwestern Patagonia and then for southern South America, combining our results with available database information consisting of igneous crystallization ages and isotopic data of the Devonian to early Carboniferous magmatic units, tectonic‐metamorphic analyses, and thermochronologic record. This study allows for distinguishing retreating and advancing subduction switching in northwestern Patagonia (38°30′ to 44°S) and a contrasting coetaneous evolution for basement outcrops exposed further north (27°30′ and 37°30′S). The early middle Devonian (400–380 Ma) northwestern Patagonian magmatism is characterized by widespread magmatism and positive εHf–εNd linked to forearc and backarc magmatism that evolved within a retreating subduction stage. A tectonic switching toward advancing orogeny stage began in the late Devonian, evidenced by a lull in magmatic activity with a negative εHf–εNd trend, possibly contemporaneous with the first tectonic‐metamorphic event in western Patagonia. An early Carboniferous magmatic gap, followed by the subsequent development of the main foliation in the basement during the Carboniferous‐Permian period, denotes the acme of this contractional stage. In contrast, the Devonian period in the northern segment is characterized by mostly negative εHf–εNd values, reverse shear zone activity in the foreland, and an inboard magmatism migration, evidencing a compressive tectonic setting that changed to an extensional configuration in the early Carboniferous with widespread arc magmatism development.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"4 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138541379","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. Hemelsdaël, O. Averbuch, L. Beccaletto, A. Izart, S. Marc, L. Capar, R. Michels
Abstract A new structural model is presented for the Permo‐Carboniferous Lorraine Basin (NE France), a major intramountain basin that developed during the latest stages of the Variscan orogeny (ca. 315–270 Ma). Digitalized well logs and reprocessed seismic data were used to decipher the kinematic evolution of this basin located along the Rhenohercynian orogenic suture zone. The basin was initiated during the late collision stage (Early to Middle Pennsylvanian) in a wedge‐top position upon the Saxothuringian retro‐wedge. The syn‐orogenic sequence is delimited to the north by the major SE‐verging Metz Thrust, which is part of the backthrust system that propagated during Middle Pennsylvanian (Late Westphalian). Seismic data provide evidence of negative tectonic inversion, allowing the formation of syn‐rift depocenters (Late Pennsylvanian‐Early Permian) above the former anticlines. Erosion of these anticlines results in a major unconformity marking the onset of post‐orogenic collapse. The late Early Permian shortening (Saalian phase) is suggested to reactivate former thrusts and normal faults, thus generating late uplift of the basin. The post‐orogenic phase is complex and diachronous at basin scale, and both compression and extension can be recorded in the same area over a short period (<10 Myr). The Late Carboniferous negative tectonic inversion along the Rhenohercynian suture zone is proposed to result from the lithospheric delamination of the Variscan orogenic roots. The associated upwelling of asthenospheric material is recorded by intense magmatic activity, and can be, in turn, considered as the main trigger for the subsequent thermal subsidence of the Mesozoic Paris Basin.
{"title":"A Deformed Wedge‐Top Basin Inverted During the Collapse of the Variscan Belt: The Permo‐Carboniferous Lorraine Basin (NE France)","authors":"R. Hemelsdaël, O. Averbuch, L. Beccaletto, A. Izart, S. Marc, L. Capar, R. Michels","doi":"10.1029/2022tc007668","DOIUrl":"https://doi.org/10.1029/2022tc007668","url":null,"abstract":"Abstract A new structural model is presented for the Permo‐Carboniferous Lorraine Basin (NE France), a major intramountain basin that developed during the latest stages of the Variscan orogeny (ca. 315–270 Ma). Digitalized well logs and reprocessed seismic data were used to decipher the kinematic evolution of this basin located along the Rhenohercynian orogenic suture zone. The basin was initiated during the late collision stage (Early to Middle Pennsylvanian) in a wedge‐top position upon the Saxothuringian retro‐wedge. The syn‐orogenic sequence is delimited to the north by the major SE‐verging Metz Thrust, which is part of the backthrust system that propagated during Middle Pennsylvanian (Late Westphalian). Seismic data provide evidence of negative tectonic inversion, allowing the formation of syn‐rift depocenters (Late Pennsylvanian‐Early Permian) above the former anticlines. Erosion of these anticlines results in a major unconformity marking the onset of post‐orogenic collapse. The late Early Permian shortening (Saalian phase) is suggested to reactivate former thrusts and normal faults, thus generating late uplift of the basin. The post‐orogenic phase is complex and diachronous at basin scale, and both compression and extension can be recorded in the same area over a short period (<10 Myr). The Late Carboniferous negative tectonic inversion along the Rhenohercynian suture zone is proposed to result from the lithospheric delamination of the Variscan orogenic roots. The associated upwelling of asthenospheric material is recorded by intense magmatic activity, and can be, in turn, considered as the main trigger for the subsequent thermal subsidence of the Mesozoic Paris Basin.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"58 1-2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135715081","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}
Norbert Caldera, Antonio Teixell, Albert Griera, Pierre Labaume, Marc Guardia
Abstract The Eaux‐Chaudes massif provides keys to unravel the deep‐seated deformation of the Iberian rifted margin during the Alpine orogeny in the Pyrenees. The massif conforms to an inlier of upper Cretaceous carbonate rocks within the Paleozoic basement of the western Axial Zone, originally deposited in the upper margin shelf before the Cenozoic collision. New geological mapping and cross‐section construction lead to the description of the lateral structural variation from a km‐scale fold nappe in the west to a ductile, imbricate fold‐thrust fan in the east. The transition from a Variscan pluton to Devonian metasediments underlying the autochthonous Cretaceous induced this structural change. Recumbent folding, which involved upper Paleozoic rocks, was facilitated by a lower detachment in Silurian slates and an upper detachment in an overlying Keuper shale and evaporite thrust sheet. Remnants of this allochthonous sheet form shale and ophite bodies pinched within the upper Cretaceous carbonates, conforming unusual tertiary welds. Ductile shear in the overturned limb of the Eaux‐Chaudes fold nappe imparted strong mylonitic foliation in carbonate rocks, often accompanied by N‐S stretching lineation and top‐to‐the‐south kinematic indicators. The burial of the massif by basement‐involved thrust sheets and the Keuper sheet, along with their Mesozoic‐Cenozoic cover, account for ductile deformation conditions and a structural style not reported hitherto for the Alpine Pyrenees. A hypothesis for the tectonic restoration of this part of the Pyrenean hinterland is finally proposed.
{"title":"Alpine Ductile Deformation of the Upper Iberian Collided Margin (Eaux‐Chaudes Massif, West‐Central Pyrenean Hinterland, France)","authors":"Norbert Caldera, Antonio Teixell, Albert Griera, Pierre Labaume, Marc Guardia","doi":"10.1029/2023tc007828","DOIUrl":"https://doi.org/10.1029/2023tc007828","url":null,"abstract":"Abstract The Eaux‐Chaudes massif provides keys to unravel the deep‐seated deformation of the Iberian rifted margin during the Alpine orogeny in the Pyrenees. The massif conforms to an inlier of upper Cretaceous carbonate rocks within the Paleozoic basement of the western Axial Zone, originally deposited in the upper margin shelf before the Cenozoic collision. New geological mapping and cross‐section construction lead to the description of the lateral structural variation from a km‐scale fold nappe in the west to a ductile, imbricate fold‐thrust fan in the east. The transition from a Variscan pluton to Devonian metasediments underlying the autochthonous Cretaceous induced this structural change. Recumbent folding, which involved upper Paleozoic rocks, was facilitated by a lower detachment in Silurian slates and an upper detachment in an overlying Keuper shale and evaporite thrust sheet. Remnants of this allochthonous sheet form shale and ophite bodies pinched within the upper Cretaceous carbonates, conforming unusual tertiary welds. Ductile shear in the overturned limb of the Eaux‐Chaudes fold nappe imparted strong mylonitic foliation in carbonate rocks, often accompanied by N‐S stretching lineation and top‐to‐the‐south kinematic indicators. The burial of the massif by basement‐involved thrust sheets and the Keuper sheet, along with their Mesozoic‐Cenozoic cover, account for ductile deformation conditions and a structural style not reported hitherto for the Alpine Pyrenees. A hypothesis for the tectonic restoration of this part of the Pyrenean hinterland is finally proposed.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"100 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135411858","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}
Pouye Yazdi, Julián García‐Mayordomo, José Antonio Álvarez‐Gómez, Jorge Miguel Gaspar‐Escribano, Eulália Masana
Abstract Understanding the crustal fault interaction and connection between earthquakes in areas with slow tectonic deformation, such as Betic Cordillera (South Spain), is challenging. When seismic rates are low and large destructive earthquakes happen less frequently, it is necessary to resort to historical or paleoseismic records. This study investigates the postseismic viscoelastic relaxation mechanism as a potential explanation for the occurrence of three historical earthquakes (I EMS VIII‐IX) in the Eastern Betic Shear Zone during the XVI‐century, all of which occurred within a span of 13 years: 1518 Vera Mw6.2, 1522 Alhama de Almeria Mw6.5, and 1531 Baza Mw6.2 associated with the Palomares, Carboneras, and Baza faults, respectively. The results strongly suggest a sequential stress‐triggering connection between the three events. The northern NS‐oriented section of the Baza fault is found to have experienced a larger positive ΔCFS and, indeed, more prone to rupture in 1531. The study also examines whether the cumulative ΔCFS had influenced the occurrence of further significant earthquakes (≥Mw6.0) in the region. A triggering connection between the cascade and the 1658 Almeria Mw6.2 earthquake is suggested, whereas no indications of similar linkage to the 1674 Lorca Mw6.0 or the 1804 Dalias Mw6.4 events are found. The stress triggering impact of the cascade over nearby active faults is noteworthy. It is expected that this analysis could have future applications for studying other important historical events, and improving seismic hazard analysis in complex fault settings of the Betic Cordillera.
在西班牙南部的Betic Cordillera等构造变形缓慢的地区，了解地壳断层的相互作用和地震之间的联系是一个具有挑战性的问题。当地震率较低，大的破坏性地震发生的频率较低时，有必要求助于历史或古地震记录。本文研究了16世纪东贝提克剪切带发生的三次历史地震(I EMS VIII - IX)的震后粘弹性松弛机制，这些地震分别发生在1518年Vera Mw6.2、1522年Alhama de Almeria Mw6.5和1531年Baza Mw6.2，这些地震分别与Palomares、Carboneras和Baza断层有关。结果强烈表明，这三个事件之间存在连续的应力触发联系。巴扎断层的北NS向部分在1531年经历了更大的正ΔCFS，确实更容易破裂。研究还考察了累积的ΔCFS是否影响了该地区进一步的大地震(≥Mw6.0)的发生。该级联与1658年Almeria Mw6.2地震之间存在触发联系，而与1674年Lorca Mw6.0或1804年Dalias Mw6.4事件之间没有发现类似联系的迹象。级联对附近活动断层的应力触发影响值得注意。预计该分析在其他重要历史事件的研究中具有一定的应用前景，并可进一步提高对北纬科迪勒拉复杂断层背景下地震危险性的分析。
{"title":"Exploring the Connection of XVI‐Century Major Historical Earthquakes in the Eastern Betic Cordillera, Spain: Insights From Viscoelastic Relaxation of the Lithosphere","authors":"Pouye Yazdi, Julián García‐Mayordomo, José Antonio Álvarez‐Gómez, Jorge Miguel Gaspar‐Escribano, Eulália Masana","doi":"10.1029/2023tc007917","DOIUrl":"https://doi.org/10.1029/2023tc007917","url":null,"abstract":"Abstract Understanding the crustal fault interaction and connection between earthquakes in areas with slow tectonic deformation, such as Betic Cordillera (South Spain), is challenging. When seismic rates are low and large destructive earthquakes happen less frequently, it is necessary to resort to historical or paleoseismic records. This study investigates the postseismic viscoelastic relaxation mechanism as a potential explanation for the occurrence of three historical earthquakes (I EMS VIII‐IX) in the Eastern Betic Shear Zone during the XVI‐century, all of which occurred within a span of 13 years: 1518 Vera Mw6.2, 1522 Alhama de Almeria Mw6.5, and 1531 Baza Mw6.2 associated with the Palomares, Carboneras, and Baza faults, respectively. The results strongly suggest a sequential stress‐triggering connection between the three events. The northern NS‐oriented section of the Baza fault is found to have experienced a larger positive ΔCFS and, indeed, more prone to rupture in 1531. The study also examines whether the cumulative ΔCFS had influenced the occurrence of further significant earthquakes (≥Mw6.0) in the region. A triggering connection between the cascade and the 1658 Almeria Mw6.2 earthquake is suggested, whereas no indications of similar linkage to the 1674 Lorca Mw6.0 or the 1804 Dalias Mw6.4 events are found. The stress triggering impact of the cascade over nearby active faults is noteworthy. It is expected that this analysis could have future applications for studying other important historical events, and improving seismic hazard analysis in complex fault settings of the Betic Cordillera.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"57 3-4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135715083","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}
L. Meng, Y. Chu, Wei Lin, Liang Zhao, Wei Wei, Fei Liu, Yin Wang, Chaojing Song, Qinying Wu
Cyclical change in subduction angle is the favorable mechanism to elucidate the cyclicity of continental arc magmatism, however, the role of episodic tectonics and variation of the lithosphere in overriding plates is much underestimated. Here we focus on structural, magnetic, and gravitational features of the Late Jurassic to Early Cretaceous granites in the Mesozoic Paleo‐Pacific arc system of the North China block. By unraveling the emplacement process and regional tectonics, we establish a three‐staged extension‐contraction cycle with crustal thickness variation controlling the magmatic flux and behavior. The Late Jurassic extension produced high‐flux crustal‐derived magma (1.87 × 103 km2/Myr), but the thick crust >45 km accumulated large granitic batholiths by multi‐feeders emplacement at the middle‐lower crust and prevented magma ascent and eruption. Subsequently, the Latest Jurassic to Earliest Cretaceous contraction resulted in the magmatic lull and thickened crust of ca. 60 km, fueling crustal material for the ensuing magmatism. In the Early Cretaceous, intense crustal extension thinned the crust to 30 km and largely enhanced the magmatic flux (3.03 × 103 km2/Myr). The magma is prone to penetrate the thin crust with an intensive eruption. A small amount of magma was stored, and the emplacement was controlled by ductile detachments or normal faults. Our model emphasizes episodic the deformation of lithosphere and associated crustal thickness variation in controlling magma production, which may shed new light in understanding the magmatic cyclicity under continuous subduction.
{"title":"Decoding the Link Between Magmatic Cyclicity and Episodic Variation of Tectonics and Crustal Thickness in the Overriding Plate","authors":"L. Meng, Y. Chu, Wei Lin, Liang Zhao, Wei Wei, Fei Liu, Yin Wang, Chaojing Song, Qinying Wu","doi":"10.1029/2023TC008040","DOIUrl":"https://doi.org/10.1029/2023TC008040","url":null,"abstract":"Cyclical change in subduction angle is the favorable mechanism to elucidate the cyclicity of continental arc magmatism, however, the role of episodic tectonics and variation of the lithosphere in overriding plates is much underestimated. Here we focus on structural, magnetic, and gravitational features of the Late Jurassic to Early Cretaceous granites in the Mesozoic Paleo‐Pacific arc system of the North China block. By unraveling the emplacement process and regional tectonics, we establish a three‐staged extension‐contraction cycle with crustal thickness variation controlling the magmatic flux and behavior. The Late Jurassic extension produced high‐flux crustal‐derived magma (1.87 × 103 km2/Myr), but the thick crust >45 km accumulated large granitic batholiths by multi‐feeders emplacement at the middle‐lower crust and prevented magma ascent and eruption. Subsequently, the Latest Jurassic to Earliest Cretaceous contraction resulted in the magmatic lull and thickened crust of ca. 60 km, fueling crustal material for the ensuing magmatism. In the Early Cretaceous, intense crustal extension thinned the crust to 30 km and largely enhanced the magmatic flux (3.03 × 103 km2/Myr). The magma is prone to penetrate the thin crust with an intensive eruption. A small amount of magma was stored, and the emplacement was controlled by ductile detachments or normal faults. Our model emphasizes episodic the deformation of lithosphere and associated crustal thickness variation in controlling magma production, which may shed new light in understanding the magmatic cyclicity under continuous subduction.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"13 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139303434","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}
Biswajit Mandal, V. Vijaya Rao, P. Karuppannan, K. Laxminarayana, Sumer Chopra, M. Ravi Kumar, Prakash Kumar
Abstract Deep crustal seismic reflection profiling is carried out for first time across various tectonic domains of seismically active Mesozoic Kachchh rift basin, formed during the breakup of Gondwanaland. The seismic data, processed using the common reflection surface stack approach, provided maiden images of the shallow and deep sub‐surface structures in the region. These images reveal a 15 km thick subhorizontal lower crustal reflection fabric and crustal‐scale domal‐type structure extending from the surface to the Moho. We interpret the earlier structure represent magmatic underplating and the latter as the Kachchh Mainland uplift. We find large variations in the thickness of sediments from 150 m to 6.5 km and crustal thickness from 45 to 35 km from north to south, with a Moho up warp of 4 km beneath the Kachchh Mainland fault. The Kachchh rift basin exhibits an unusually thick crust of 45 km, contrary to many rift basins. We interpret the syn‐rifting and the Reunion mantle plume activity, manifested as Deccan volcanics, are responsible for magmatic underplating and crustal thickening. Uplift in the region is multi‐genetic in origin. Present study illuminated new faults and nature of various other faults. Moderate to large earthquakes in the region are attributed to the regional and local stresses resulting from the plate boundary and heterogeneous crustal structure. Based on the mafic lower crust and distribution of aftershocks through the entire crust, we interpret the lower crust is brittle, contrary to most models of continental rheology.
{"title":"Deep Seismic Reflection Imaging of Mesozoic Kachchh Rift, NW India: Implications for Evolution","authors":"Biswajit Mandal, V. Vijaya Rao, P. Karuppannan, K. Laxminarayana, Sumer Chopra, M. Ravi Kumar, Prakash Kumar","doi":"10.1029/2023tc007992","DOIUrl":"https://doi.org/10.1029/2023tc007992","url":null,"abstract":"Abstract Deep crustal seismic reflection profiling is carried out for first time across various tectonic domains of seismically active Mesozoic Kachchh rift basin, formed during the breakup of Gondwanaland. The seismic data, processed using the common reflection surface stack approach, provided maiden images of the shallow and deep sub‐surface structures in the region. These images reveal a 15 km thick subhorizontal lower crustal reflection fabric and crustal‐scale domal‐type structure extending from the surface to the Moho. We interpret the earlier structure represent magmatic underplating and the latter as the Kachchh Mainland uplift. We find large variations in the thickness of sediments from 150 m to 6.5 km and crustal thickness from 45 to 35 km from north to south, with a Moho up warp of 4 km beneath the Kachchh Mainland fault. The Kachchh rift basin exhibits an unusually thick crust of 45 km, contrary to many rift basins. We interpret the syn‐rifting and the Reunion mantle plume activity, manifested as Deccan volcanics, are responsible for magmatic underplating and crustal thickening. Uplift in the region is multi‐genetic in origin. Present study illuminated new faults and nature of various other faults. Moderate to large earthquakes in the region are attributed to the regional and local stresses resulting from the plate boundary and heterogeneous crustal structure. Based on the mafic lower crust and distribution of aftershocks through the entire crust, we interpret the lower crust is brittle, contrary to most models of continental rheology.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"18 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135510583","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}
J. B. Ruh, L. Valero, M. Najafi, N. Etemad‐Saeed, J. Vouga, A. Mohammadi, F. Landtwing, M. Guillong, M. Cobianchi, N. Mancin
Abstract Sediments deposited into foreland basins can provide valuable insights related to the geological evolution of their hinterlands. Located in the peripheral foreland of the South Sistan Suture Zone (SE Iran), the Karvandar Basin exhibits a several‐kilometer‐thick shallow‐marine to continental clastic sedimentary sequence forming elongated sub‐circular synclines. These synclines overlie a mud‐dominated formation with exotic volcanic blocks that hosts one of Iran's largest mud volcano, known as Pirgel. In this study, we present a ∼3.5‐km‐thick magnetostratigraphic section and U‐Pb zircon ages of interlayered tuffs that constrain a depositional age of the Karvandar Basin of ∼24–17 Ma. Sandstone and microconglomerate framework analyses and paleocurrent directions suggest a first‐cycle active volcanic arc source to the northeast of the basin. We interpret the mud‐dominated lithology with volcanic blocks as an olistostrome originating from a similar source as the overlying clastic sequence. The deposition of the olistostrome is dated at ∼24.5 Ma by a U‐Pb calcite age from a coral block. The absence of large‐scale anticlines and the occurrence of angular unconformities suggest that the sub‐circular synclines in the Karvandar Basin formed by gravity‐driven downbuilding into the unconsolidated fluid‐saturated olistostrome, resembling salt‐related minibasins. Integrated results indicate that a late Oligocene to early Miocene Makran volcanic arc represents the source of the clastic sequence. Hence, our results provide new constraints on the initiation of arc volcanism related to the Makran subduction zone, predating earliest reported ages from the Mirabad pluton (19 Ma) to the northeast of the Karvandar Basin by ∼5 Myr.
{"title":"Tectono‐Sedimentary Evolution of Shale‐Related Minibasins in the Karvandar Basin (South Sistan, SE Iran): Insights From Magnetostratigraphy, Isotopic Dating, and Sandstone Petrology","authors":"J. B. Ruh, L. Valero, M. Najafi, N. Etemad‐Saeed, J. Vouga, A. Mohammadi, F. Landtwing, M. Guillong, M. Cobianchi, N. Mancin","doi":"10.1029/2023tc007971","DOIUrl":"https://doi.org/10.1029/2023tc007971","url":null,"abstract":"Abstract Sediments deposited into foreland basins can provide valuable insights related to the geological evolution of their hinterlands. Located in the peripheral foreland of the South Sistan Suture Zone (SE Iran), the Karvandar Basin exhibits a several‐kilometer‐thick shallow‐marine to continental clastic sedimentary sequence forming elongated sub‐circular synclines. These synclines overlie a mud‐dominated formation with exotic volcanic blocks that hosts one of Iran's largest mud volcano, known as Pirgel. In this study, we present a ∼3.5‐km‐thick magnetostratigraphic section and U‐Pb zircon ages of interlayered tuffs that constrain a depositional age of the Karvandar Basin of ∼24–17 Ma. Sandstone and microconglomerate framework analyses and paleocurrent directions suggest a first‐cycle active volcanic arc source to the northeast of the basin. We interpret the mud‐dominated lithology with volcanic blocks as an olistostrome originating from a similar source as the overlying clastic sequence. The deposition of the olistostrome is dated at ∼24.5 Ma by a U‐Pb calcite age from a coral block. The absence of large‐scale anticlines and the occurrence of angular unconformities suggest that the sub‐circular synclines in the Karvandar Basin formed by gravity‐driven downbuilding into the unconsolidated fluid‐saturated olistostrome, resembling salt‐related minibasins. Integrated results indicate that a late Oligocene to early Miocene Makran volcanic arc represents the source of the clastic sequence. Hence, our results provide new constraints on the initiation of arc volcanism related to the Makran subduction zone, predating earliest reported ages from the Mirabad pluton (19 Ma) to the northeast of the Karvandar Basin by ∼5 Myr.","PeriodicalId":22351,"journal":{"name":"Tectonics","volume":"7 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135371879","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}
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