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Globally significant mass of terrestrial organic carbon efficiently transported by canyon-flushing turbidity currents 全球大量陆地有机碳通过峡谷冲刷浊流有效迁移

Geology Pub Date : 2024-06-13 DOI: 10.1130/g51976.1

Megan L. Baker, S. Hage, P. Talling, S. Açikalin, Robert G. Hilton, N. Haghipour, Sean C. Ruffell, E. Pope, Ricardo Silva Jacinto, M. Clare, Sefa Sahin

{"title":"Globally significant mass of terrestrial organic carbon efficiently transported by canyon-flushing turbidity currents","authors":"Megan L. Baker, S. Hage, P. Talling, S. Açikalin, Robert G. Hilton, N. Haghipour, Sean C. Ruffell, E. Pope, Ricardo Silva Jacinto, M. Clare, Sefa Sahin","doi":"10.1130/g51976.1","DOIUrl":"https://doi.org/10.1130/g51976.1","url":null,"abstract":"Burial of organic carbon in marine sediments is a long-term sink of atmospheric CO2, and submarine turbidity currents are volumetrically the most important sediment transport process on Earth. Yet the processes, amounts, and efficiency of organic carbon transfer by turbidity currents through submarine canyons to the deep sea are poorly documented and understood. We present an organic carbon budget for the submarine Congo Canyon, offshore West Africa, constrained with time-lapse bathymetry, sediment cores, and flow monitoring, including the effects of two >1000-km-runout canyon-flushing turbidity currents. In one year, flows eroded an estimated 6.09 ± 2.70 Mt of previously buried terrestrial organic carbon in the canyon, primarily from fine-grained and vegetation-rich muddy sand facies with high organic carbon contents (as high as 11%). The age and composition of organic carbon in the Congo Canyon is comparable to those in the Congo River, indicating that transfer is efficient. Over the whole canyon-channel system, we extrapolate that 43 ± 15 Mt of organic carbon was eroded and transported to the deep (> 5 km) sea, equivalent to 22% of the annual global particulate organic carbon export from rivers to oceans and 54%−108% of the predicted annual terrestrial organic carbon burial in the oceans. Canyon-flushing turbidity currents carried a globally significant mass of terrestrial organic carbon down just one submarine canyon in a single year, indicating their importance for redistribution and delivery of organic carbon to the deep sea.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"60 27","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141346819","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

Generation of Archean TTGs via sluggish subduction 通过迟缓俯冲生成阿新世熱帶地壳

Geology Pub Date : 2024-06-13 DOI: 10.1130/g52196.1

Bradford J. Foley

引用次数: 0

Fingerprinting enhanced floodplain reworking during the Paleocene−Eocene Thermal Maximum in the Southern Pyrenees (Spain): Implications for channel dynamics and carbon burial 在南比利牛斯山（西班牙）古新世-始新世热极盛时期，指纹识别增强了洪泛区再加工：对河道动力学和碳埋藏的影响

Geology Pub Date : 2024-05-23 DOI: 10.1130/g52180.1

Marine Prieur, Alexander C. Whittaker, P. Nuriel, Rocío Jaimes-Gutierrez, Eduardo Garzanti, M. Roigé, T. Sømme, Fritz Schlunegger, S. Castelltort

{"title":"Fingerprinting enhanced floodplain reworking during the Paleocene−Eocene Thermal Maximum in the Southern Pyrenees (Spain): Implications for channel dynamics and carbon burial","authors":"Marine Prieur, Alexander C. Whittaker, P. Nuriel, Rocío Jaimes-Gutierrez, Eduardo Garzanti, M. Roigé, T. Sømme, Fritz Schlunegger, S. Castelltort","doi":"10.1130/g52180.1","DOIUrl":"https://doi.org/10.1130/g52180.1","url":null,"abstract":"The sedimentary record of the Paleocene−Eocene Thermal Maximum (PETM, ca. 56 Ma) allows the study of feedback mechanisms over the entire duration of a climatic event, from carbon release to the subsequent recovery phase. Clay sedimentation increase in the oceans during the PETM is linked to enhanced terrestrial erosion. Fluvial channel mobility has been invoked to explain this increase in fine sediment export based on more frequent transitional avulsions. In this study, we test whether the reworking of Microcodium (prismatic calcite concretions) from the floodplain to marine environments can serve to fingerprint floodplain reworking due to channel mobility. We quantified the abundance of floodplain-sourced Microcodium grains reworked in fluvial to marine sandstones pre-dating and coeval to the PETM in the Southern Pyrenees (Tremp Basin, Spain). Laser ablation−inductively coupled plasma−mass spectrometry U-Pb ages on calcite confirm the Thanetian age of the Microcodium grains. Our data show a four-fold increase in the export of floodplain sediments to the marine domain during the PETM. Moreover, we show that this is predominantly due to enhanced channel mobility, reworking channel banks and interfluves, with increased erosion in the hinterland as a secondary factor. This increase in floodplain reworking would correspond to an increase in biospheric carbon burial flux by a factor of 2.2. Therefore, enhanced channel mobility and fine-grain sediment transport to the oceans during a climatic perturbation such as the PETM may constitute an important negative feedback mechanism.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"25 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141105671","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

Early Mississippian global δ13C excursion is not a diagenetic artifact 密西西比早期的全球δ13C偏移并非成岩作用的产物

Geology Pub Date : 2024-05-23 DOI: 10.1130/g52109.1

Matthew Braun, Noah T. Anderson, Kristin D. Bergmann, Elizabeth M. Griffith, M. Saltzman

{"title":"Early Mississippian global δ13C excursion is not a diagenetic artifact","authors":"Matthew Braun, Noah T. Anderson, Kristin D. Bergmann, Elizabeth M. Griffith, M. Saltzman","doi":"10.1130/g52109.1","DOIUrl":"https://doi.org/10.1130/g52109.1","url":null,"abstract":"Shallow-water platform carbonate δ13C may provide a record of changes in ocean chemistry through time, but early marine diagenesis and local processes can decouple these records from the global carbon cycle. Recent studies of calcium isotopes (δ44/40Ca) in shallow-water carbonates indicate that δ44/40Ca can be altered during early marine diagenesis, implying that δ13C may also potentially be altered. Here, we tested the hypothesis that the platform carbonate δ13C record of the Kinderhookian-Osagean boundary excursion (KOBE), ∼353 m.y. ago, reflects a period of global diagenesis using paired isotopic (δ44/40Ca and clumped isotopes) and trace-element geochemistry from three sections in the United States. There is little evidence for covariation between δ44/40Ca and δ13C during the KOBE. Clumped isotopes from our shallowest section support primarily sediment-buffered diagenesis at relatively low temperatures. We conclude that the δ13C record of the KOBE as recorded in shallow-water carbonate is consistent with a shift in the dissolved inorganic carbon reservoir and that, more generally, ancient shallow-water carbonates can retain records of primary seawater chemistry.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"29 33","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141104036","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

Late Oligocene−Miocene evolution of deep-water circulation in the abyssal South China Sea: Insights from Nd isotopes of fossil fish teeth 晚渐新世-中新世南海深海环流的演变：从化石鱼齿的钕同位素中获得的启示

Geology Pub Date : 2024-05-23 DOI: 10.1130/g52042.1

Wei Shu, Christophe Colin, Zhifei Liu, Arnaud Dapoigny

{"title":"Late Oligocene−Miocene evolution of deep-water circulation in the abyssal South China Sea: Insights from Nd isotopes of fossil fish teeth","authors":"Wei Shu, Christophe Colin, Zhifei Liu, Arnaud Dapoigny","doi":"10.1130/g52042.1","DOIUrl":"https://doi.org/10.1130/g52042.1","url":null,"abstract":"A long-term neodymium isotope (εNd) record of fossil fish teeth was investigated to constrain the evolution of deep-water circulation in the abyssal South China Sea (SCS) during the late Oligocene−Miocene (27−10 Ma). Fish teeth samples were collected from the oceanic red beds at International Ocean Discovery Program Expedition 367 Site U1499 (water depth 3758 m). Seawater εNd values (from −7.1 to −4.8, average −6.1) prior to 15 Ma indicate that water masses in the abyssal SCS resulted from the mixing of more radiogenic Upper Circumpolar Deep Water (UCDW, average −4.5) and less radiogenic Lower Circumpolar Deep Water (LCDW, average −6.4). The general decrease in εNd values was attributed to an increasing influence of the unradiogenic LCDW at the studied site, consistent with the subsidence and the associated deepening of the SCS plain. After 15 Ma, seawater εNd dropped significantly to a range of −8.9 to −6.1 (average −7.5), indicating a slowdown in the hydrological connection between the deep-water masses in the SCS and the western Pacific Ocean. We argue that the formation of the Luzon Strait due to the uplift of the Luzon arc in the late Miocene led to the shallowing and narrowing of the SCS-Pacific channels. Consequently, penetration of LCDW was reduced and water masses in the abyssal SCS would have been less ventilated and strongly influenced by lithogenic input from the unradiogenic sediments of large Asian rivers draining the peri-Himalayan region.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"66 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141105935","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

U-Pb calcite ages date oblique rifting of the Arctic−North Atlantic gateway 北极-北大西洋门户斜裂的U-Pb方解石年代测定

Geology Pub Date : 2024-05-21 DOI: 10.1130/g52140.1

L.C. Haaland, T. Slagstad, P. Osmundsen, T. Redfield

{"title":"U-Pb calcite ages date oblique rifting of the Arctic−North Atlantic gateway","authors":"L.C. Haaland, T. Slagstad, P. Osmundsen, T. Redfield","doi":"10.1130/g52140.1","DOIUrl":"https://doi.org/10.1130/g52140.1","url":null,"abstract":"Miocene breakup of Svalbard from Greenland formed a deep oceanic gateway that enabled circulation between the Arctic and Atlantic Oceans, significantly changing the global climate. However, the timing of events remains unclear. An excellent opportunity to constrain this timing is found onshore western Svalbard, where the Sarsbukta fault forms the eastern margin of the Eocene−Oligocene Forlandsundet basin. Here, we present new results from U-Pb dating of calcite precipitated in fault-related veins to constrain the timing of Sarsbukta fault deformation and the evolution of the basin. Our oldest calcite age is Permo-Triassic, suggesting long-lived deformation along the fault. A cluster of ages between 41 and 33 Ma overlaps with fossil-based depositional ages from parts of the Forlandsundet basin. These data indicate that onshore transtension partly pre-dated the well-established Chron 13 (magnetic polarity time scale; 35.5−33.7 Ma) reorganization of spreading ridges in the North Atlantic. Our youngest age of 13 Ma indicates that faulting persisted long after the preserved basin fill was deposited. If seafloor spreading marked the end of extension of continental crust, Molloy Ridge spreading during Chron 5 (19.6−9.8 Ma) may have initiated after 13 Ma.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141113958","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

Millennial-scale climate cycles modulated by Milankovitch forcing in the middle Cambrian (ca. 500 Ma) Marjum Formation, Utah, USA 美国犹他州中寒武纪（约 500 Ma）Marjum 地层中受 Milankovitch 迫力调节的千年尺度气候循环

Geology Pub Date : 2024-05-17 DOI: 10.1130/g52182.1

Damien Pas, Maya Elrick, A. Da Silva, Linda Hinnov, Valentin Jamart, Marion Thaureau, Michiel Arts

{"title":"Millennial-scale climate cycles modulated by Milankovitch forcing in the middle Cambrian (ca. 500 Ma) Marjum Formation, Utah, USA","authors":"Damien Pas, Maya Elrick, A. Da Silva, Linda Hinnov, Valentin Jamart, Marion Thaureau, Michiel Arts","doi":"10.1130/g52182.1","DOIUrl":"https://doi.org/10.1130/g52182.1","url":null,"abstract":"Middle Cambrian offshore deposits of the Marjum Formation, Utah, USA, are characterized by four scales of superimposed cyclicity defined by varying fine siliciclastic versus limestone abundances; these include limestone-marl couplets (rhythmites; 5−10 cm), which are bundled into parasequences (1−2 m) and small-scale (5−10 m) and large-scale (20−40 m) sequences. Time series analysis of SiO2 and lithologic rank stratigraphic series reveal cycles consistent with Milankovitch periods corresponding to Cambrian orbital eccentricity (20 m, 405 k.y.; ∼6 m 110 k.y.), obliquity (1.8 m, 30 k.y.), climatic precession (1.15 m, ∼18 k.y.), and half-precession (0.64 m, 7 k.y.). Astronomical calibration of the lithologic rank series indicates that the main sub-Milankovitch cycle at 0.065 m represents ∼1 k.y. and corresponds to the basic rhythmite couplet. All scales of cyclicity are interpreted as the result of wet versus dry monsoonal climate oscillations controlling the abundance of fine siliciclastic sediment influx to the basin. A plausible millennial-scale climate driver is solar activity. These results describe one of the oldest known geological candidates for solar-influenced climate change modulated by Milankovitch forcing.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"115 28","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141126348","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

A sea of change: Tracing parasitic dynamics through the past millennia in the northern Adriatic, Italy 沧海桑田：追溯意大利亚得里亚海北部过去几千年的寄生动态

Geology Pub Date : 2024-05-16 DOI: 10.1130/g52187.1

Erin Fitzgerald, Delaney Ryan, D. Scarponi, J. Huntley

引用次数: 0

Oligocene and Miocene blowtorch volcanism within the California Borderland and its influence on the plate-boundary transition 加利福尼亚边界地带的渐新世和中新世喷火火山活动及其对板块边界过渡的影响

Geology Pub Date : 2024-05-14 DOI: 10.1130/g52175.1

Andrea Marie Balbas, Kevin Konrad, Nathan W. Onderdonk, P. Castillo, Richard Behl

{"title":"Oligocene and Miocene blowtorch volcanism within the California Borderland and its influence on the plate-boundary transition","authors":"Andrea Marie Balbas, Kevin Konrad, Nathan W. Onderdonk, P. Castillo, Richard Behl","doi":"10.1130/g52175.1","DOIUrl":"https://doi.org/10.1130/g52175.1","url":null,"abstract":"The California Borderland is a uniquely broad and complex region of the North American−Pacific transform margin. Oligocene to Miocene structural reorganization, including large-magnitude extension and vertical-axis rotation of crustal blocks, formed a network of submerged fault-bounded basins, ridges, and islands offshore of southern California during its evolution from a convergent to transform boundary. Here, we report new 40Ar/39Ar incremental heating age determinations and geochemical analyses of volcanic rocks in the California Borderland, as well as a reconciled regional tectonic model. The California Borderland volcanic rocks are calc-alkaline in composition and mostly silica-oversaturated and represent relatively large-degree partial melts of the asthenosphere that incorporated hydrated forearc lithospheric components. A temporal reconciliation of these records shows that subduction of an active spreading center starting in the Oligocene and again in the Miocene was the critical control on the observed volcanism at ca. 31−30 Ma and 19−13 Ma. We posit that prolonged trench-ridge interaction generated a blowtorch effect, which resulted in widespread forearc volcanism and weakening of the crust to facilitate the unique deformation styles documented in the borderland that did not occur elsewhere along the North American−Pacific plate boundary.","PeriodicalId":503125,"journal":{"name":"Geology","volume":"23 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140982123","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

Intact stalked crinoids from the late Aptian of NE Spain offer insights into the Mesozoic Marine Revolution in the Tethys 西班牙东北部始新纪晚期出土的完好无损的有柄棘皮动物为了解特提斯中生代海洋革命提供了线索

Geology Pub Date : 2024-05-10 DOI: 10.1130/g52179.1

Á. García-Penas, T. Baumiller, Marcos Aurell, Samuel Zamora

{"title":"Intact stalked crinoids from the late Aptian of NE Spain offer insights into the Mesozoic Marine Revolution in the Tethys","authors":"Á. García-Penas, T. Baumiller, Marcos Aurell, Samuel Zamora","doi":"10.1130/g52179.1","DOIUrl":"https://doi.org/10.1130/g52179.1","url":null,"abstract":"Stalked crinoids were common in shallow-marine habitats in the geologic past but are today restricted to the deep sea. The timing of the shift in their bathymetric distribution has been discussed in the context of the Mesozoic Marine Revolution (MMR), one of the most important episodes of change in marine ecosystems of the Phanerozoic, which is generally thought to have begun sometime in the Late Triassic. However, the record of Cretaceous stalked crinoids is poor, consisting primarily of disarticulated ossicles for which the provenance is often difficult to determine, hampering interpretations of the habitat in which they lived. Here, we report on well-preserved isocrinids from the Aptian and use a multidisciplinary approach involving sedimentological, isotopic, and paleontological data to demonstrate that they inhabited a shallow lagoon subject to salinity variations. This suggests that their absence from such environments today is not a function of physicochemical factors and reinforces the idea that predation pressure may have played a critical role in their bathymetric distribution. The influence of predation is supported by the first Early Cretaceous record of a regenerating arm.","PeriodicalId":503125,"journal":{"name":"Geology","volume":" 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140990366","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