Geology最新文献_第6页

Hydrologically driven modulation of cutoff regime in meandering rivers 水文驱动的蜿蜒河流断流机制调节

Geology Pub Date : 2024-02-14 DOI: 10.1130/g51783.1

Riccardo Maitan, A. Finotello, D. Tognin, A. D’Alpaos, Christopher R. Fielding, A. Ielpi, M. Ghinassi

{"title":"Hydrologically driven modulation of cutoff regime in meandering rivers","authors":"Riccardo Maitan, A. Finotello, D. Tognin, A. D’Alpaos, Christopher R. Fielding, A. Ielpi, M. Ghinassi","doi":"10.1130/g51783.1","DOIUrl":"https://doi.org/10.1130/g51783.1","url":null,"abstract":"Bend cutoff is a fundamental process shaping meandering rivers. Despite the widely accepted differentiation between neck and chute cutoffs, a significant knowledge gap persists regarding the factors responsible for the occurrence of each cutoff regime and the specific conditions triggering the regime. Here, we used field and photogrammetric data derived from a global set of 22 meandering rivers, stretching more than 5500 km in total river length, to disentangle the controlling factors behind the cutoff regime in meandering rivers. We found that whether a meandering river forms a chute rather than neck meander cutoff depends primarily on the variability of overbank discharges. Short-lived, high-magnitude overbank floods promote the formation of chute cutoffs, aided by (though not required) reduced riparian vegetation density, enhanced stream power, and flow confinement within the river valley. In contrast, neck cutoffs are prevalent in rivers characterized by limited variations in bankfull hydrology, typically associated with low-magnitude, long-lasting overbank floods. Distinct cutoff regimes also discernibly affected floodplain geomorphology, with a chute regime resulting in more frequent cutoff occurrences. Our results suggest that human-induced alterations of river hydrologic regime can potentially cause fundamental shifts in the cutoff behavior of meandering rivers, thus affecting sediment residence time and carbon fluxes in alluvial floodplains.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139778304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hydrologically driven modulation of cutoff regime in meandering rivers 水文驱动的蜿蜒河流断流机制调节

Geology Pub Date : 2024-02-14 DOI: 10.1130/g51783.1

Riccardo Maitan, A. Finotello, D. Tognin, A. D’Alpaos, Christopher R. Fielding, A. Ielpi, M. Ghinassi

{"title":"Hydrologically driven modulation of cutoff regime in meandering rivers","authors":"Riccardo Maitan, A. Finotello, D. Tognin, A. D’Alpaos, Christopher R. Fielding, A. Ielpi, M. Ghinassi","doi":"10.1130/g51783.1","DOIUrl":"https://doi.org/10.1130/g51783.1","url":null,"abstract":"Bend cutoff is a fundamental process shaping meandering rivers. Despite the widely accepted differentiation between neck and chute cutoffs, a significant knowledge gap persists regarding the factors responsible for the occurrence of each cutoff regime and the specific conditions triggering the regime. Here, we used field and photogrammetric data derived from a global set of 22 meandering rivers, stretching more than 5500 km in total river length, to disentangle the controlling factors behind the cutoff regime in meandering rivers. We found that whether a meandering river forms a chute rather than neck meander cutoff depends primarily on the variability of overbank discharges. Short-lived, high-magnitude overbank floods promote the formation of chute cutoffs, aided by (though not required) reduced riparian vegetation density, enhanced stream power, and flow confinement within the river valley. In contrast, neck cutoffs are prevalent in rivers characterized by limited variations in bankfull hydrology, typically associated with low-magnitude, long-lasting overbank floods. Distinct cutoff regimes also discernibly affected floodplain geomorphology, with a chute regime resulting in more frequent cutoff occurrences. Our results suggest that human-induced alterations of river hydrologic regime can potentially cause fundamental shifts in the cutoff behavior of meandering rivers, thus affecting sediment residence time and carbon fluxes in alluvial floodplains.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139837742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hydrological fluctuations in the Tarim Basin, northwest China, over the past millennium 中国西北塔里木盆地过去千年的水文波动

Geology Pub Date : 2024-02-14 DOI: 10.1130/g51962.1

Kangkang Li, Xiaoguang Qin, G. Plunkett, David Brown, Bing Xu, Lei Zhang, Zhaoyan Gu, Guijin Mu, H. Jia, Zhiqiang Yin, Jiaqi Liu

{"title":"Hydrological fluctuations in the Tarim Basin, northwest China, over the past millennium","authors":"Kangkang Li, Xiaoguang Qin, G. Plunkett, David Brown, Bing Xu, Lei Zhang, Zhaoyan Gu, Guijin Mu, H. Jia, Zhiqiang Yin, Jiaqi Liu","doi":"10.1130/g51962.1","DOIUrl":"https://doi.org/10.1130/g51962.1","url":null,"abstract":"Reconstruction of hydrological fluctuations in arid regions has proven challenging due to a lack of reliable chronologic constraints on sparse geological archives. The aim of this study was to establish an independent record of hydrologic changes in the hyper-arid Tarim Basin (TB; northwest China) with high spatiotemporal resolution. We present comprehensive radiocarbon and tree-ring data sets of subfossilized plant remains in the TB compiled from geomorphological investigations of the paleochannels of the Tarim River (TR), the longest endorheic river in China, crossing the world’s second-largest shifting sand desert. Results show that the late medieval configuration of the TR basin was characterized by enhanced hydrological connectivity, as indicated by the formation of significant riparian forests in the desert regions at ca. 1170 CE. A distinct low-flow interval (ca. 1500−1650 CE) is identified for the first time, refining the period of a wetter-than-present TB. The present-day organization of streams in the lower TR was proto-formed after the dry period, possibly led by episodic flood-induced diversion. Our study describes the centennial-scale dynamics in the TR flow over the past millennium, offering a robust long-term context for hydrological assessment in the extensive drylands of the Asian interior.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139778083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Hydrological fluctuations in the Tarim Basin, northwest China, over the past millennium 中国西北塔里木盆地过去千年的水文波动

Geology Pub Date : 2024-02-14 DOI: 10.1130/g51962.1

Kangkang Li, Xiaoguang Qin, G. Plunkett, David Brown, Bing Xu, Lei Zhang, Zhaoyan Gu, Guijin Mu, H. Jia, Zhiqiang Yin, Jiaqi Liu

{"title":"Hydrological fluctuations in the Tarim Basin, northwest China, over the past millennium","authors":"Kangkang Li, Xiaoguang Qin, G. Plunkett, David Brown, Bing Xu, Lei Zhang, Zhaoyan Gu, Guijin Mu, H. Jia, Zhiqiang Yin, Jiaqi Liu","doi":"10.1130/g51962.1","DOIUrl":"https://doi.org/10.1130/g51962.1","url":null,"abstract":"Reconstruction of hydrological fluctuations in arid regions has proven challenging due to a lack of reliable chronologic constraints on sparse geological archives. The aim of this study was to establish an independent record of hydrologic changes in the hyper-arid Tarim Basin (TB; northwest China) with high spatiotemporal resolution. We present comprehensive radiocarbon and tree-ring data sets of subfossilized plant remains in the TB compiled from geomorphological investigations of the paleochannels of the Tarim River (TR), the longest endorheic river in China, crossing the world’s second-largest shifting sand desert. Results show that the late medieval configuration of the TR basin was characterized by enhanced hydrological connectivity, as indicated by the formation of significant riparian forests in the desert regions at ca. 1170 CE. A distinct low-flow interval (ca. 1500−1650 CE) is identified for the first time, refining the period of a wetter-than-present TB. The present-day organization of streams in the lower TR was proto-formed after the dry period, possibly led by episodic flood-induced diversion. Our study describes the centennial-scale dynamics in the TR flow over the past millennium, offering a robust long-term context for hydrological assessment in the extensive drylands of the Asian interior.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139837921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Gibraltar subduction zone is invading the Atlantic 直布罗陀俯冲带正在侵入大西洋

Geology Pub Date : 2024-02-13 DOI: 10.1130/g51654.1

João C. Duarte, Nicolas Riel, F. Rosas, Anton Popov, Christian Schuler, B. Kaus

{"title":"Gibraltar subduction zone is invading the Atlantic","authors":"João C. Duarte, Nicolas Riel, F. Rosas, Anton Popov, Christian Schuler, B. Kaus","doi":"10.1130/g51654.1","DOIUrl":"https://doi.org/10.1130/g51654.1","url":null,"abstract":"Subduction initiation is a cornerstone of the Wilson cycle. It marks the turning point in an ocean’s lifetime, allowing its lithosphere to be recycled into the mantle. However, formation of new subduction zones in Atlantic-type oceans is challenging, given that it commonly involves the action of an external force, such as the slab pull from a nearby subduction zone, a far-field compression, or the impact of a plume. Notwithstanding, the Atlantic already has two subduction zones, the Lesser Antilles and the Scotia arcs. These subduction zones have been forced from the nearby Pacific subduction zones. The Gibraltar arc is another place where a subduction zone is invading the Atlantic. This corresponds to a direct migration of a subduction zone that developed in the closing Mediterranean Basin. Nevertheless, few authors consider the Gibraltar subduction to be still active because it has significantly slowed down in the past millions of years. Here, we use new gravity-driven geodynamic models that reproduce the evolution of the Western Mediterranean, show how the Gibraltar arc formed, and test if it is still active. The results suggest that the arc will propagate farther into the Atlantic after a period of quiescence. The models also show how a subduction zone starting in a closing ocean (Ligurian Ocean) can migrate into a new opening ocean (Atlantic) through a narrow oceanic corridor. Subduction invasion is likely a common mechanism of subduction initiation in Atlantic-type oceans and a fundamental process in the recent geological evolution of Earth.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139780295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Gibraltar subduction zone is invading the Atlantic 直布罗陀俯冲带正在侵入大西洋

Geology Pub Date : 2024-02-13 DOI: 10.1130/g51654.1

João C. Duarte, Nicolas Riel, F. Rosas, Anton Popov, Christian Schuler, B. Kaus

{"title":"Gibraltar subduction zone is invading the Atlantic","authors":"João C. Duarte, Nicolas Riel, F. Rosas, Anton Popov, Christian Schuler, B. Kaus","doi":"10.1130/g51654.1","DOIUrl":"https://doi.org/10.1130/g51654.1","url":null,"abstract":"Subduction initiation is a cornerstone of the Wilson cycle. It marks the turning point in an ocean’s lifetime, allowing its lithosphere to be recycled into the mantle. However, formation of new subduction zones in Atlantic-type oceans is challenging, given that it commonly involves the action of an external force, such as the slab pull from a nearby subduction zone, a far-field compression, or the impact of a plume. Notwithstanding, the Atlantic already has two subduction zones, the Lesser Antilles and the Scotia arcs. These subduction zones have been forced from the nearby Pacific subduction zones. The Gibraltar arc is another place where a subduction zone is invading the Atlantic. This corresponds to a direct migration of a subduction zone that developed in the closing Mediterranean Basin. Nevertheless, few authors consider the Gibraltar subduction to be still active because it has significantly slowed down in the past millions of years. Here, we use new gravity-driven geodynamic models that reproduce the evolution of the Western Mediterranean, show how the Gibraltar arc formed, and test if it is still active. The results suggest that the arc will propagate farther into the Atlantic after a period of quiescence. The models also show how a subduction zone starting in a closing ocean (Ligurian Ocean) can migrate into a new opening ocean (Atlantic) through a narrow oceanic corridor. Subduction invasion is likely a common mechanism of subduction initiation in Atlantic-type oceans and a fundamental process in the recent geological evolution of Earth.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139840149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recognizing big mantle wedges in deep time: Constraints from the Western Mongolia Collage in Central Asia 识别深时大地幔楔：中亚西蒙古拼贴地的制约因素

Geology Pub Date : 2024-02-12 DOI: 10.1130/g51841.1

X. Cui, Peter A. Cawood, Min Sun, Guochun Zhao

{"title":"Recognizing big mantle wedges in deep time: Constraints from the Western Mongolia Collage in Central Asia","authors":"X. Cui, Peter A. Cawood, Min Sun, Guochun Zhao","doi":"10.1130/g51841.1","DOIUrl":"https://doi.org/10.1130/g51841.1","url":null,"abstract":"A big mantle wedge (BMW) is defined as the broad region of upper mantle above a stagnant slab in the mantle transition zone (MTZ). It is a common and significant structure within Earth’s interior at modern convergent plate margins as revealed by seismic data yet rarely identified in fossil convergent systems. We propose the existence of a BMW beneath the Western Mongolia Collage during the early to middle Paleozoic based on a comprehensive chronology of geological events that characterized the accretionary orogen in this region. The trench-arc system initially developed above a NE-dipping subduction zone, with subduction-related arc magmatism clustered at ca. 530−490 Ma and accumulations of flysch-like sequences from the Cambrian to early Silurian constituting the accretionary wedge of the Altai Zone. The westward migration of the arc was likely driven by slab rollback and trench retreat, leading to gradual formation of a BMW as the slab stagnated at the MTZ. The BMW influenced the tectonic evolution of the entire Western Mongolia Collage, inducing Ordovician−Silurian intraplate magmatism in regions inboard of the migrating magmatic arc and the potential opening of the Mongol-Okhotsk Ocean. Westward movement of the trench-arc continued until the Devonian, resulting in back-arc basin formation in the Chinese Altai and intraplate magmatism in the Hovd and Lake Zones of the Western Mongolia Collage, forming a trench−arc−back-arc and intraplate tectonic system. Mantle flow within the BMW is inferred to have impacted magmatism, basin migration, and the stress and thermal state of the overriding plate.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139844650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recognizing big mantle wedges in deep time: Constraints from the Western Mongolia Collage in Central Asia 识别深时大地幔楔：中亚西蒙古拼贴地的制约因素

Geology Pub Date : 2024-02-12 DOI: 10.1130/g51841.1

X. Cui, Peter A. Cawood, Min Sun, Guochun Zhao

{"title":"Recognizing big mantle wedges in deep time: Constraints from the Western Mongolia Collage in Central Asia","authors":"X. Cui, Peter A. Cawood, Min Sun, Guochun Zhao","doi":"10.1130/g51841.1","DOIUrl":"https://doi.org/10.1130/g51841.1","url":null,"abstract":"A big mantle wedge (BMW) is defined as the broad region of upper mantle above a stagnant slab in the mantle transition zone (MTZ). It is a common and significant structure within Earth’s interior at modern convergent plate margins as revealed by seismic data yet rarely identified in fossil convergent systems. We propose the existence of a BMW beneath the Western Mongolia Collage during the early to middle Paleozoic based on a comprehensive chronology of geological events that characterized the accretionary orogen in this region. The trench-arc system initially developed above a NE-dipping subduction zone, with subduction-related arc magmatism clustered at ca. 530−490 Ma and accumulations of flysch-like sequences from the Cambrian to early Silurian constituting the accretionary wedge of the Altai Zone. The westward migration of the arc was likely driven by slab rollback and trench retreat, leading to gradual formation of a BMW as the slab stagnated at the MTZ. The BMW influenced the tectonic evolution of the entire Western Mongolia Collage, inducing Ordovician−Silurian intraplate magmatism in regions inboard of the migrating magmatic arc and the potential opening of the Mongol-Okhotsk Ocean. Westward movement of the trench-arc continued until the Devonian, resulting in back-arc basin formation in the Chinese Altai and intraplate magmatism in the Hovd and Lake Zones of the Western Mongolia Collage, forming a trench−arc−back-arc and intraplate tectonic system. Mantle flow within the BMW is inferred to have impacted magmatism, basin migration, and the stress and thermal state of the overriding plate.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139784724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Geoelectric evidence for a wide spatial footprint of active extension in central Colorado 科罗拉多州中部活动延伸的广泛空间足迹的地电证据

Geology Pub Date : 2024-02-09 DOI: 10.1130/g51517.1

Benjamin S. Murphy, J. Caine, P. Bedrosian, Jade Crosbie

引用次数: 0

Tidal dissipation morphodynamic feedback triggers loss of microtidal marshes 潮汐消散的形态动力反馈引发了微潮沼泽的消失

Geology Pub Date : 2024-02-09 DOI: 10.1130/g51798.1

S. Zapp, G. Mariotti

引用次数: 0