M.C. Zarazúa-Carbajal, G.A. Valentine, S. De la Cruz-Reyna
Alluvial processes acting on scoria cones cause the development of a drainage network composed of radially distributed rills and gullies parallel to the volcanic edifice's downslope direction. We quantify the degree of drainage network development by applying the Average Erosion Index (AEI) method to scoria cones from the arid to semi-arid Lunar Crater volcanic field (Nevada, United States) and comparing our results with previously obtained results from two tropical volcanic fields (Sierra Chichinautzin volcanic field and the Parícutin-Tancítaro region, both in central Mexico). We show that the AEI method is useful in determining geomorphic age relations when calibrated separately for each field. Furthermore, the differences in AEI results for the three studied fields indicate that the method provides a way of quantifying the effects of different alluvial erosion rates at volcanic fields across various environments, including a delay in alluvial processes on cones in arid settings that has been qualitatively inferred by previous studies.
{"title":"Scoria cone erosional degradation by incision: Different behaviors in three volcanic fields reflect environmental conditions","authors":"M.C. Zarazúa-Carbajal, G.A. Valentine, S. De la Cruz-Reyna","doi":"10.1130/g52113.1","DOIUrl":"https://doi.org/10.1130/g52113.1","url":null,"abstract":"Alluvial processes acting on scoria cones cause the development of a drainage network composed of radially distributed rills and gullies parallel to the volcanic edifice's downslope direction. We quantify the degree of drainage network development by applying the Average Erosion Index (AEI) method to scoria cones from the arid to semi-arid Lunar Crater volcanic field (Nevada, United States) and comparing our results with previously obtained results from two tropical volcanic fields (Sierra Chichinautzin volcanic field and the Parícutin-Tancítaro region, both in central Mexico). We show that the AEI method is useful in determining geomorphic age relations when calibrated separately for each field. Furthermore, the differences in AEI results for the three studied fields indicate that the method provides a way of quantifying the effects of different alluvial erosion rates at volcanic fields across various environments, including a delay in alluvial processes on cones in arid settings that has been qualitatively inferred by previous studies.","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141475318","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}
Dunfan Wang, Yihui Chen, Yan Liu, Andrew P. Roberts, Eelco J. Rohling, Xiangyu Zhao, Xu Zhang, Jinhua Li, Weiqi Yao, Xuejiao Qu, Xianfeng Tan, Qingsong Liu
Global cooling with the onset of Antarctic glaciation ca. 34 Ma across the Eocene-Oligocene transition (EOT) terminated the early Cenozoic greenhouse climate state and marked the beginning of icehouse conditions. Although a pCO2 decline is considered to have been a major cause of this climate shift, the associated carbon-sequestration mechanism remains unclear. Here, we assessed ocean production and circulation changes across the EOT using numerical simulations combined with a novel proxy, namely, bacterial magnetofossils, the abundance and morphology of which are sensitive to sedimentary organic matter accumulation and oxygenation. We detected production and oxygenation declines in the equatorial Pacific Ocean coeval with increased biological production in the Southern Ocean after the EOT. Corroborated by simulation results and evidence from the Subantarctic region, we interpret this counterintuitive combination as a result of enhanced bottom-water formation and biological pump efficiency in the Southern Ocean due to Antarctic glacial buildup across the EOT. These results provide key evidence for deep Pacific Ocean deoxygenation and increased respired carbon concentrations, which amplified CO2 decline across the EOT.
{"title":"Bacterial magnetofossil evidence for enhanced Pacific Ocean respired carbon storage during buildup of Antarctic glaciation","authors":"Dunfan Wang, Yihui Chen, Yan Liu, Andrew P. Roberts, Eelco J. Rohling, Xiangyu Zhao, Xu Zhang, Jinhua Li, Weiqi Yao, Xuejiao Qu, Xianfeng Tan, Qingsong Liu","doi":"10.1130/g52016.1","DOIUrl":"https://doi.org/10.1130/g52016.1","url":null,"abstract":"Global cooling with the onset of Antarctic glaciation ca. 34 Ma across the Eocene-Oligocene transition (EOT) terminated the early Cenozoic greenhouse climate state and marked the beginning of icehouse conditions. Although a pCO2 decline is considered to have been a major cause of this climate shift, the associated carbon-sequestration mechanism remains unclear. Here, we assessed ocean production and circulation changes across the EOT using numerical simulations combined with a novel proxy, namely, bacterial magnetofossils, the abundance and morphology of which are sensitive to sedimentary organic matter accumulation and oxygenation. We detected production and oxygenation declines in the equatorial Pacific Ocean coeval with increased biological production in the Southern Ocean after the EOT. Corroborated by simulation results and evidence from the Subantarctic region, we interpret this counterintuitive combination as a result of enhanced bottom-water formation and biological pump efficiency in the Southern Ocean due to Antarctic glacial buildup across the EOT. These results provide key evidence for deep Pacific Ocean deoxygenation and increased respired carbon concentrations, which amplified CO2 decline across the EOT.","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141463916","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}
Jonah S. McLeod, Alexander C. Whittaker, Rebecca E. Bell, Gary J. Hampson, Stephen E. Watkins, Sam A.S. Brooke, Nahin Rezwan, Joel Hook, Jesse R. Zondervan, Vamsi Ganti, Sinéad J. Lyster
Sediment transport in rivers is not steady through time. Highly intermittent river systems, which only transport bedload during the most significant flow events, are particularly sensitive to changes in climate and precipitation patterns. People and landscapes can be vulnerable to fluvial processes, and quantifying river intermittency is critical for assessing landscape response to projected changes in precipitation extremes due to climate change. We generated new constraints on recent to modern fluvial intermittency factors—the frequency at which bedload is mobilized in a river—based on field measurements in the Corinth Rift, Greece, and Holocene sediment accumulation rates. Results reveal some of the lowest documented intermittency factors to date, showing Mediterranean rivers can transport an entire annual sediment load in a rare storm event. Coupling intermittency calculations with historical flood and precipitation data indicates these rivers transport bedload during one storm every ~4 yr, associated with rainfall >50 mm/d, and subsequent floods; this hydroclimate is typical across the Mediterranean region. Furthermore, climate models predict precipitation extremes will increase across Europe, and the frequency of events that surpass thresholds of sediment transport will increase significantly, potentially causing sediment loads to double by 2100 CE. As the area of arid land likely to host intermittent rivers also increases, sensitive landscapes are on the edge of significant geomorphic change, driven by global warming.
{"title":"Landscapes on the edge: River intermittency in a warming world","authors":"Jonah S. McLeod, Alexander C. Whittaker, Rebecca E. Bell, Gary J. Hampson, Stephen E. Watkins, Sam A.S. Brooke, Nahin Rezwan, Joel Hook, Jesse R. Zondervan, Vamsi Ganti, Sinéad J. Lyster","doi":"10.1130/g52043.1","DOIUrl":"https://doi.org/10.1130/g52043.1","url":null,"abstract":"Sediment transport in rivers is not steady through time. Highly intermittent river systems, which only transport bedload during the most significant flow events, are particularly sensitive to changes in climate and precipitation patterns. People and landscapes can be vulnerable to fluvial processes, and quantifying river intermittency is critical for assessing landscape response to projected changes in precipitation extremes due to climate change. We generated new constraints on recent to modern fluvial intermittency factors—the frequency at which bedload is mobilized in a river—based on field measurements in the Corinth Rift, Greece, and Holocene sediment accumulation rates. Results reveal some of the lowest documented intermittency factors to date, showing Mediterranean rivers can transport an entire annual sediment load in a rare storm event. Coupling intermittency calculations with historical flood and precipitation data indicates these rivers transport bedload during one storm every ~4 yr, associated with rainfall >50 mm/d, and subsequent floods; this hydroclimate is typical across the Mediterranean region. Furthermore, climate models predict precipitation extremes will increase across Europe, and the frequency of events that surpass thresholds of sediment transport will increase significantly, potentially causing sediment loads to double by 2100 CE. As the area of arid land likely to host intermittent rivers also increases, sensitive landscapes are on the edge of significant geomorphic change, driven by global warming.","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141475316","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}
Microplastics are widely distributed in deep oceans, with some of the highest concentrations reported in submarine canyons, which are thought to be closely related to turbidity currents. However, the turbidity current role in microplastic transport and deposition is poorly understood. Here, we present temporal variation in microplastic abundance and settling flux from sediment trap observations on the levee of Gaoping Canyon, offshore Taiwan, where turbidity currents occur frequently. The results showed that relatively high microplastic abundance and flux were consistent with the increases of near-bottom suspended sediment concentration caused by turbidity currents. The microplastics, dominated by polypropylene (59%) and polyethylene (21%), were probably derived from Taiwan coastal resuspension and river input and then transported into the submarine canyon by typhoon- or earthquake-triggered turbidity currents. During the turbidity currents, the average microplastic abundance and flux was 4137 particles per kilogram and 40.11 particles per square meter per day, respectively, showing an increase of 49% and 270%, respectively, compared to non−turbidity current periods. The total microplastic flux during the turbidity currents accounted for ∼76% of annual flux. Our study highlights turbidity currents to be the major hydrodynamic process in regulating microplastic transport and settling in a submarine canyon.
{"title":"Turbidity currents regulate the transport and settling of microplastics in a deep-sea submarine canyon","authors":"Xiaodong Zhang, Zhifei Liu, Daoji Li, Yulong Zhao, Yanwei Zhang","doi":"10.1130/g52116.1","DOIUrl":"https://doi.org/10.1130/g52116.1","url":null,"abstract":"Microplastics are widely distributed in deep oceans, with some of the highest concentrations reported in submarine canyons, which are thought to be closely related to turbidity currents. However, the turbidity current role in microplastic transport and deposition is poorly understood. Here, we present temporal variation in microplastic abundance and settling flux from sediment trap observations on the levee of Gaoping Canyon, offshore Taiwan, where turbidity currents occur frequently. The results showed that relatively high microplastic abundance and flux were consistent with the increases of near-bottom suspended sediment concentration caused by turbidity currents. The microplastics, dominated by polypropylene (59%) and polyethylene (21%), were probably derived from Taiwan coastal resuspension and river input and then transported into the submarine canyon by typhoon- or earthquake-triggered turbidity currents. During the turbidity currents, the average microplastic abundance and flux was 4137 particles per kilogram and 40.11 particles per square meter per day, respectively, showing an increase of 49% and 270%, respectively, compared to non−turbidity current periods. The total microplastic flux during the turbidity currents accounted for ∼76% of annual flux. Our study highlights turbidity currents to be the major hydrodynamic process in regulating microplastic transport and settling in a submarine canyon.","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141266344","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}
{"title":"Fluvial response to Late Pleistocene–Holocene climate change in the Colorado River drainage, central Texas, USA: COMMENT","authors":"Mike Blum, Dustin Sweet","doi":"10.1130/g51850c.1","DOIUrl":"https://doi.org/10.1130/g51850c.1","url":null,"abstract":"Abstract not available","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140814414","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}
{"title":"Fluvial response to Late Pleistocene–Holocene climate change in the Colorado River drainage, central Texas, USA: REPLY","authors":"E. Gabriela Gutiérrez, Daniel F. Stockli","doi":"10.1130/g52087y.1","DOIUrl":"https://doi.org/10.1130/g52087y.1","url":null,"abstract":"Abstract not available","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140814428","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}
Juan Pedro Rodríguez-López, Carlos L. Liesa, Aránzazu Luzón, Arsenio Muñoz, María J. Mayayo, Julian B. Murton, Ana R. Soria
Abstract not available
无摘要
{"title":"Ice-rafted dropstones at midlatitudes in the Cretaceous of continental, Iberia: REPLY","authors":"Juan Pedro Rodríguez-López, Carlos L. Liesa, Aránzazu Luzón, Arsenio Muñoz, María J. Mayayo, Julian B. Murton, Ana R. Soria","doi":"10.1130/g52152y.1","DOIUrl":"https://doi.org/10.1130/g52152y.1","url":null,"abstract":"Abstract not available","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140346097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Isabel Benito, I. Emma Quijada, Martín Garcia-Martín, Alejandro Pertuz, Pablo Suarez-Gonzalez, Angélica Torices, Sonia Campos-Soto
Abstract not available
无摘要
{"title":"Ice-rafted dropstones at midlatitudes in the Cretaceous of continental Iberia: COMMENT","authors":"M. Isabel Benito, I. Emma Quijada, Martín Garcia-Martín, Alejandro Pertuz, Pablo Suarez-Gonzalez, Angélica Torices, Sonia Campos-Soto","doi":"10.1130/g52006c.1","DOIUrl":"https://doi.org/10.1130/g52006c.1","url":null,"abstract":"Abstract not available","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140340768","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}
Chen Wu, Andrew V. Zuza, Drew A. Levy, Jie Li, Lin Ding
Abstract not available
无摘要
{"title":"Discovery of Permian–Triassic eclogite in northern Tibet establishes coeval subduction erosion along an ~3000-km-long arc: REPLY","authors":"Chen Wu, Andrew V. Zuza, Drew A. Levy, Jie Li, Lin Ding","doi":"10.1130/g52012y.1","DOIUrl":"https://doi.org/10.1130/g52012y.1","url":null,"abstract":"Abstract not available","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140000852","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}
Antoine Bénard, Dmitri A. Ionov, Oliver Nebel, Richard J. Arculus
Abstract not available
无摘要
{"title":"Boninitic melt percolation makes depleted mantle wedges rich in silica: COMMENT","authors":"Antoine Bénard, Dmitri A. Ionov, Oliver Nebel, Richard J. Arculus","doi":"10.1130/g51824c.1","DOIUrl":"https://doi.org/10.1130/g51824c.1","url":null,"abstract":"Abstract not available","PeriodicalId":12642,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":5.8,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140015521","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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