IF 5.8 1区地球科学

Geology Pub Date : 2024-07-01 DOI: 10.1130/g52016.1

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

{"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":"72 1","pages":""},"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}

引用次数: 0

Landscapes on the edge: River intermittency in a warming world 边缘景观：变暖世界中的河流间歇

IF 5.8 1区地球科学

Geology Pub Date : 2024-07-01 DOI: 10.1130/g52043.1

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

{"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":"92 1","pages":""},"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}

引用次数: 0

Fluvial response to Late Pleistocene–Holocene climate change in the Colorado River drainage, central Texas, USA: COMMENT 美国得克萨斯州中部科罗拉多河流域晚更新世-全新世气候变化的冲积响应：COMMENT

IF 5.8 1区地球科学

Geology Pub Date : 2024-05-01 DOI: 10.1130/g51850c.1

Mike Blum, Dustin Sweet

引用次数: 0

Fluvial response to Late Pleistocene–Holocene climate change in the Colorado River drainage, central Texas, USA: REPLY 美国得克萨斯州中部科罗拉多河流域晚更新世-全新世气候变化的冲积响应：REPLY

IF 5.8 1区地球科学

Geology Pub Date : 2024-05-01 DOI: 10.1130/g52087y.1

E. Gabriela Gutiérrez, Daniel F. Stockli

引用次数: 0

Ice-rafted dropstones at midlatitudes in the Cretaceous of continental, Iberia: REPLY 伊比利亚大陆白垩纪中纬度地区的冰蚀滴石：REPLY