Pub Date : 2025-10-01DOI: 10.1016/j.margeo.2025.107661
S.P.S. Gulick , P. Kaskes , C.M. Lowery , A.S.P. Rae , S.M. Tikoo
In 2016, International Ocean Discovery Program Expedition 364, with support from the International Continental Scientific Drilling Program, drilled into the peak ring of the Chicxulub impact structure, famous for its causal link to the mass extinction at the end of the Cretaceous. In this summary paper, we discuss key findings from Site M0077 on the cratering processes, marine ecosystem recovery after the mass extinction, and the post-impact hydrothermal system and habitability of the impact structure. Important results include (1) the confirmation of the dynamic collapse model of peak ring formation, (2) insights into impactite emplacement processes on Earth, where water is a key component, (3) discovery of the iridium anomaly within the impact basin, unequivocally linking the Chicxulub impact basin to the global Cretaceous-Paleogene (K-Pg) boundary layer, (4) evidence for key atmospheric inputs of dust, sulfate aerosols, and soot, all likely contributing to global cooling and reduction of photosynthesis as drivers for extinction, (5) rapid recovery of life within the ocean overlying the crater, including a primary succession driven by in part by picoplankton before a transition over 100 s kyr to diversifying planktic communities, and (6) the presence of a long-lived hydrothermal system with extant thermophilic life in the buried peak ring 66 Myr later. The Chicxulub crater represents exceptional scientific opportunity in that it bridges planetary science, impact dynamics, and astrobiology; the integration of such findings continue to reveal the transformative power of asteroid impacts as a major geologic and biologic process.
{"title":"From impact to extinction to recovery: Discoveries of IODP-ICDP Expedition 364 to the Chicxulub impact structure","authors":"S.P.S. Gulick , P. Kaskes , C.M. Lowery , A.S.P. Rae , S.M. Tikoo","doi":"10.1016/j.margeo.2025.107661","DOIUrl":"10.1016/j.margeo.2025.107661","url":null,"abstract":"<div><div>In 2016, International Ocean Discovery Program Expedition 364, with support from the International Continental Scientific Drilling Program, drilled into the peak ring of the Chicxulub impact structure, famous for its causal link to the mass extinction at the end of the Cretaceous. In this summary paper, we discuss key findings from Site M0077 on the cratering processes, marine ecosystem recovery after the mass extinction, and the post-impact hydrothermal system and habitability of the impact structure. Important results include (1) the confirmation of the dynamic collapse model of peak ring formation, (2) insights into impactite emplacement processes on Earth, where water is a key component, (3) discovery of the iridium anomaly within the impact basin, unequivocally linking the Chicxulub impact basin to the global Cretaceous-Paleogene (K-Pg) boundary layer, (4) evidence for key atmospheric inputs of dust, sulfate aerosols, and soot, all likely contributing to global cooling and reduction of photosynthesis as drivers for extinction, (5) rapid recovery of life within the ocean overlying the crater, including a primary succession driven by in part by picoplankton before a transition over 100 s kyr to diversifying planktic communities, and (6) the presence of a long-lived hydrothermal system with extant thermophilic life in the buried peak ring 66 Myr later. The Chicxulub crater represents exceptional scientific opportunity in that it bridges planetary science, impact dynamics, and astrobiology; the integration of such findings continue to reveal the transformative power of asteroid impacts as a major geologic and biologic process.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107661"},"PeriodicalIF":2.2,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145334751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-26DOI: 10.1016/j.margeo.2025.107660
Florian Jacques , Alexandre Normandeau , Jean-Carlos Montero-Serrano , Guillaume St-Onge , Audrey Limoges , André Rochon , Urs Neumeier , Patrick Lajeunesse , Daniel Bourgault
The recurrence of turbidity currents in submarine canyons is often assessed using sediment core records from submarine fans, which are generally assumed to reflect canyon processes. However, this assumption has rarely been tested. Here, we assess the completeness of modern sedimentary records in the Pointe-des-Monts submarine fan, located in the Lower St. Lawrence Estuary, eastern Canada, by comparing turbidity current activity derived from repeat multibeam bathymetry, direct monitoring observations, and short sediment cores. The timelapse bathymetry and monitoring results revealed that turbidity current activity over the last 15 years was primarily driven by storms, especially during ice-free winters. Since 2007, a minimum of nine turbidity currents were recorded by timelapse multibeam bathymetry and direct observations in the canyon system, many of which have led to the migration of cyclic steps within the canyon axis. However, turbidites recorded in the short sediment cores on the lobe predate all monitoring efforts, indicating a largely incomplete record of canyon processes preserved on the seafloor. The absence of modern turbidites (≤15 years) in the submarine fan is interpreted to result from bottom current reworking, bioturbation, and the dilution of turbidity currents as they become unconfined on the submarine fan. This study highlights that bottom currents can extensively remobilize turbidites, resulting in a largely incomplete record of turbidity currents on submarine fans. Consequently, caution is needed when reconstructing their recurrence and sediment dynamics using sediment cores, particularly in such dynamic nearshore systems.
{"title":"The incompleteness of turbidite records: Comparing direct monitoring of turbidity currents to deposits preserved in submarine fans (Pointe-des-Monts, eastern Canada)","authors":"Florian Jacques , Alexandre Normandeau , Jean-Carlos Montero-Serrano , Guillaume St-Onge , Audrey Limoges , André Rochon , Urs Neumeier , Patrick Lajeunesse , Daniel Bourgault","doi":"10.1016/j.margeo.2025.107660","DOIUrl":"10.1016/j.margeo.2025.107660","url":null,"abstract":"<div><div>The recurrence of turbidity currents in submarine canyons is often assessed using sediment core records from submarine fans, which are generally assumed to reflect canyon processes. However, this assumption has rarely been tested. Here, we assess the completeness of modern sedimentary records in the Pointe-des-Monts submarine fan, located in the Lower St. Lawrence Estuary, eastern Canada, by comparing turbidity current activity derived from repeat multibeam bathymetry, direct monitoring observations, and short sediment cores. The timelapse bathymetry and monitoring results revealed that turbidity current activity over the last 15 years was primarily driven by storms, especially during ice-free winters. Since 2007, a minimum of nine turbidity currents were recorded by timelapse multibeam bathymetry and direct observations in the canyon system, many of which have led to the migration of cyclic steps within the canyon axis. However, turbidites recorded in the short sediment cores on the lobe predate all monitoring efforts, indicating a largely incomplete record of canyon processes preserved on the seafloor. The absence of modern turbidites (≤15 years) in the submarine fan is interpreted to result from bottom current reworking, bioturbation, and the dilution of turbidity currents as they become unconfined on the submarine fan. This study highlights that bottom currents can extensively remobilize turbidites, resulting in a largely incomplete record of turbidity currents on submarine fans. Consequently, caution is needed when reconstructing their recurrence and sediment dynamics using sediment cores, particularly in such dynamic nearshore systems.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"491 ","pages":"Article 107660"},"PeriodicalIF":2.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-19DOI: 10.1016/j.margeo.2025.107659
Bei Song , Shihui Lv , Xin Su , Xuan Ding , Chunhui Tao , Chonghan Yu , Jie Zhang , Xuezhen Li
Hydrothermal plumes play a critical role in chemical fluxes and element transport in the oceans. However, the impact on the sediments along mid-ocean ridge flanks is not well constrained. In this study, samples from three sediment cores (MC03/04/05) were analyzed for their geochemical records located at the Southwest Indian Ridge (SWIR) flanks over the past 40 ka. In addition to the dominant CaO content, these flank sediments show elevated concentrations of Fe, Mn, Cu, Zn, and REEs with positive Y anomalies. We also constructed two geochemical diagrams (Cu/Zn-Mn/Fe-REE/Fe and REE/Fe vs. Mn/Fe) to identify hydrothermal plume inputs. Based on these results, we revealed four distal plume events at 32–30 ka (MC04), 16–14 ka (MC05), 10–8 ka (MC05), and 7.5–6.5 ka (MC03). Furthermore, cluster analysis indicates that these plume events originated from the Yuhuang Hydrothermal Field (YHF), and they correspond temporally to periods of sulfide formation within the field. Finally, we propose that the YHF plume dispersion was coupled with the Agulhas Return Current (ARC) migration, resulting in the following processes: (1) 32–30 ka southward ARC transported plume material to MC04; (2) 16–14 ka and 10–8 ka northward shifts deposited plume fallout at MC05; (3) 7.5–6.5 ka southward ARC movement led to MC03 deposition. Our findings reveal metal (Fe, Mn, REE) transport mechanisms from the SWIR axial zones to distal flanks, highlighting plume-ARC interactions over millennial timescales.
热液柱在海洋的化学通量和元素运输中起着关键作用。然而，对洋中脊两侧沉积物的影响并没有得到很好的限制。本文分析了西南印度洋脊（SWIR）侧翼3个沉积物岩心（MC03/04/05）过去40ka的地球化学记录。除了主要的CaO含量外，这些侧翼沉积物中Fe、Mn、Cu、Zn和ree浓度升高，Y呈阳性异常。我们还构建了Cu/Zn-Mn/Fe-REE/Fe和REE/Fe vs. Mn/Fe地球化学图来识别热液柱输入。基于这些结果，我们揭示了32-30 ka （MC04）、16-14 ka （MC05）、10-8 ka （MC05）和7.5-6.5 ka （MC03）的4次远端羽流事件。聚类分析表明，这些羽流事件起源于玉黄热液田，与该热液田内硫化物形成的时间相对应。最后，我们认为YHF羽流弥散与阿古拉斯回流（Agulhas Return Current， ARC）迁移耦合，导致以下过程：(1)32-30 ka南向ARC将羽流物质输送到MC04；(2) 16-14 ka和10-8 ka向北移动的MC05沉积羽流沉降物；(3) 7.5 ~ 6.5 ka南向弧运动导致MC03沉积。我们的发现揭示了金属（Fe, Mn， REE）从SWIR轴向区到远侧翼的运输机制，突出了千年时间尺度上羽-弧的相互作用。
{"title":"Hydrothermal plume events in a 40 kyr sediment record from the flanks of the Southwest Indian Ridge","authors":"Bei Song , Shihui Lv , Xin Su , Xuan Ding , Chunhui Tao , Chonghan Yu , Jie Zhang , Xuezhen Li","doi":"10.1016/j.margeo.2025.107659","DOIUrl":"10.1016/j.margeo.2025.107659","url":null,"abstract":"<div><div>Hydrothermal plumes play a critical role in chemical fluxes and element transport in the oceans. However, the impact on the sediments along mid-ocean ridge flanks is not well constrained. In this study, samples from three sediment cores (MC03/04/05) were analyzed for their geochemical records located at the Southwest Indian Ridge (SWIR) flanks over the past 40 ka. In addition to the dominant CaO content, these flank sediments show elevated concentrations of Fe, Mn, Cu, Zn, and REEs with positive Y anomalies. We also constructed two geochemical diagrams (Cu/Zn-Mn/Fe-REE/Fe and REE/Fe vs. Mn/Fe) to identify hydrothermal plume inputs. Based on these results, we revealed four distal plume events at 32–30 ka (MC04), 16–14 ka (MC05), 10–8 ka (MC05), and 7.5–6.5 ka (MC03). Furthermore, cluster analysis indicates that these plume events originated from the Yuhuang Hydrothermal Field (YHF), and they correspond temporally to periods of sulfide formation within the field. Finally, we propose that the YHF plume dispersion was coupled with the Agulhas Return Current (ARC) migration, resulting in the following processes: (1) 32–30 ka southward ARC transported plume material to MC04; (2) 16–14 ka and 10–8 ka northward shifts deposited plume fallout at MC05; (3) 7.5–6.5 ka southward ARC movement led to MC03 deposition. Our findings reveal metal (Fe, Mn, REE) transport mechanisms from the SWIR axial zones to distal flanks, highlighting plume-ARC interactions over millennial timescales.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107659"},"PeriodicalIF":2.2,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-17DOI: 10.1016/j.margeo.2025.107658
Amin Rahdarian , Karin R. Bryan , Mick Van Der Wegen
Estuarine channels convey tidal flow and sediments, while the direction and magnitude of tide-residual transports largely depends on the surrounding estuarine bathymetry, shoals and vegetation cover. This study explores the controls of historic morphodynamics, mangrove development and channels on landscape-scale tidal hydrodynamics around a mangrove-covered estuarine shoal in Whitianga estuary, Aotearoa New Zealand. A Delft3D hydrodynamic model was used to explore the impact of historic developments on spatial flow patterns and flow asymmetry based on an analysis of historical images of the site including conditions of the mangrove forest in the 1940s.
Model results clearly reveal areas of ebb and flood dominance in the model domain, where mangrove surrounded creeks are ebb dominant and shoal incising channels are flood dominant. Within the forest, the seaward part of mangroves is ebb-dominant, whereas a flood-dominance function in the back of the forest with higher elevated mangroves is mostly observed. Removing vegetation leads to a large-scale change in flow routing and flow asymmetry, whereas if creeks are infilled, local changes only around the location of the creeks are observed.
The movement of fine sediment fractions is inferred by the slack water duration at high tide. The existence of vegetation affects the cohesive fraction. Without vegetation, the slack water duration becomes shorter on the shoal close to the fringe, inside and the edge of the former forest while it becomes longer inside the river channel and on the edge of the shoal close to the river channel. In the scenario that channels were infilled, a longer (shorter) slack water duration at the mouth and head of channels and inside channels (around the channels) were observed.
Expansion of mangroves can cause a function shift of the channels. Model results suggest that the ebb-dominant modern-day mangrove creek was flood-dominant in 1940s prior to colonization of mangroves in the inner bend of the shoal.
{"title":"The impact of mangroves development and morphodynamics on channel function shift and flow asymmetry in an estuarine channel-shoal system","authors":"Amin Rahdarian , Karin R. Bryan , Mick Van Der Wegen","doi":"10.1016/j.margeo.2025.107658","DOIUrl":"10.1016/j.margeo.2025.107658","url":null,"abstract":"<div><div>Estuarine channels convey tidal flow and sediments, while the direction and magnitude of tide-residual transports largely depends on the surrounding estuarine bathymetry, shoals and vegetation cover. This study explores the controls of historic morphodynamics, mangrove development and channels on landscape-scale tidal hydrodynamics around a mangrove-covered estuarine shoal in Whitianga estuary, Aotearoa New Zealand. A Delft3D hydrodynamic model was used to explore the impact of historic developments on spatial flow patterns and flow asymmetry based on an analysis of historical images of the site including conditions of the mangrove forest in the 1940s.</div><div>Model results clearly reveal areas of ebb and flood dominance in the model domain, where mangrove surrounded creeks are ebb dominant and shoal incising channels are flood dominant. Within the forest, the seaward part of mangroves is ebb-dominant, whereas a flood-dominance function in the back of the forest with higher elevated mangroves is mostly observed. Removing vegetation leads to a large-scale change in flow routing and flow asymmetry, whereas if creeks are infilled, local changes only around the location of the creeks are observed.</div><div>The movement of fine sediment fractions is inferred by the slack water duration at high tide. The existence of vegetation affects the cohesive fraction. Without vegetation, the slack water duration becomes shorter on the shoal close to the fringe, inside and the edge of the former forest while it becomes longer inside the river channel and on the edge of the shoal close to the river channel. In the scenario that channels were infilled, a longer (shorter) slack water duration at the mouth and head of channels and inside channels (around the channels) were observed.</div><div>Expansion of mangroves can cause a function shift of the channels. Model results suggest that the ebb-dominant modern-day mangrove creek was flood-dominant in 1940s prior to colonization of mangroves in the inner bend of the shoal.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107658"},"PeriodicalIF":2.2,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-15DOI: 10.1016/j.margeo.2025.107642
Karen Araya , Práxedes Muñoz , Antonio Maldonado , Laurent Dezileau , Lorena Rebolledo , Gloria Sanchez , Gabriel Cantarutti
The upwelling system off Coquimbo (30°S) is strongly influenced by interannual variability driven by the El Niño-Southern Oscillation (ENSO), which decreases primary productivity and increases precipitation during the warm phase (El Niño events). This study examined the historical variations in the primary oceanographic and climatic characteristics of the region based on recent sedimentary records from Coquimbo Bay. In a sediment core (BC117; 83 cm), nine sedimentary units were identified and categorized into two groups: u1, u3, u5, and u9 represent marine sedimentation, as indicated by the major contribution of marine diatoms and higher δ13C and δ15N values reflecting marine conditions. In contrast, u4, u6 and u7 exhibited more depleted δ13C values and an increase in freshwater diatom valves, suggesting a significant continental influence, likely from alluvial events. These units showed elevated concentrations of Fe, K, and Cu and an increase in fine sediment content, likely associated with El Niño-induced heavy rainfall around 1700–1730 CE. This period was followed by a decrease in continental input owing to reduced pluviosity. Spanning from 1403 CE to 1850 CE, the core reflects a period dominated by La Niña-like conditions, sustained by an intensified Southern Oscillation Index (SOI) and diminished Interdecadal Pacific Oscillation (IPO). During this period, the seafloor experienced an increase in reduced conditions, likely leading to anoxic environments, which were subsequently followed by less reduced conditions encompassing the Current Warm Period (CWP) due to enhanced ventilation processes. Nevertheless, increasing proxies for primary productivity have suggested an intensification of upwelling in recent times. Based on the characteristics of the units, three tsunami events were characterized by a significant reduction in total diatom counts contingent on the energy of the event and a sharp basal contact between the lower undisturbed unit and the very disturbed overlying layer (1420, 1471, and 1751 CE).
{"title":"Reconstruction of oceanographic and climatic changes over the past ∼ 600 years over Coquimbo Bay, Chile (30°S)","authors":"Karen Araya , Práxedes Muñoz , Antonio Maldonado , Laurent Dezileau , Lorena Rebolledo , Gloria Sanchez , Gabriel Cantarutti","doi":"10.1016/j.margeo.2025.107642","DOIUrl":"10.1016/j.margeo.2025.107642","url":null,"abstract":"<div><div>The upwelling system off Coquimbo (30°S) is strongly influenced by interannual variability driven by the El Niño-Southern Oscillation (ENSO), which decreases primary productivity and increases precipitation during the warm phase (El Niño events). This study examined the historical variations in the primary oceanographic and climatic characteristics of the region based on recent sedimentary records from Coquimbo Bay. In a sediment core (BC117; 83 cm), nine sedimentary units were identified and categorized into two groups: u1, u3, u5, and u9 represent marine sedimentation, as indicated by the major contribution of marine diatoms and higher δ<sup>13</sup>C and δ<sup>15</sup>N values reflecting marine conditions. In contrast, u4, u6 and u7 exhibited more depleted δ<sup>13</sup>C values and an increase in freshwater diatom valves, suggesting a significant continental influence, likely from alluvial events. These units showed elevated concentrations of Fe, K, and Cu and an increase in fine sediment content, likely associated with El Niño-induced heavy rainfall around 1700–1730 CE. This period was followed by a decrease in continental input owing to reduced pluviosity. Spanning from 1403 CE to 1850 CE, the core reflects a period dominated by La Niña-like conditions, sustained by an intensified Southern Oscillation Index (SOI) and diminished Interdecadal Pacific Oscillation (IPO). During this period, the seafloor experienced an increase in reduced conditions, likely leading to anoxic environments, which were subsequently followed by less reduced conditions encompassing the Current Warm Period (CWP) due to enhanced ventilation processes. Nevertheless, increasing proxies for primary productivity have suggested an intensification of upwelling in recent times. Based on the characteristics of the units, three tsunami events were characterized by a significant reduction in total diatom counts contingent on the energy of the event and a sharp basal contact between the lower undisturbed unit and the very disturbed overlying layer (1420, 1471, and 1751 CE).</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107642"},"PeriodicalIF":2.2,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145220425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-12DOI: 10.1016/j.margeo.2025.107656
Ammoose K. Jayan , A.V. Sijinkumar , Kaustubh Thirumalai , Lael Vetter , P. John Kurian , A. Prajith , Rajveer Sharma
Extant since the Miocene, Globigerinoides ruber is a mixed-layer planktic foraminiferal species, cosmopolitan to the tropical–subtropical oceans. Globigerinoides ruber has multiple morphotypical variants with distinctive white and pink chromotypes. Today, the pink variety is exclusively found in the Atlantic Ocean and its nearby basins. For the past few decades, it was believed that pink-pigmented G. ruber disappeared from the Indo-Pacific Oceans at about 120 kyr BP. However, a recent study from the northwestern Bay of Bengal documented the presence of G. ruber (pink) in surface sediments. Hitherto, there was no evidence of G. ruber (pink) in downcore sediments from the Indian Ocean since 120 kyr BP. In this study, for the first time, we document the re-appearance of G. ruber (pink) from 30 to 8 kyr BP in gravity core MGS30/GC-03. The core was retrieved from the eastern BoB from a water depth of 1883 m, and its chronology was established using eight AMS radiocarbon dates. We observed high abundances of G. ruber (pink) during the Last Glacial Maximum (LGM) and Heinrich Event 1 and 2 (H1 and H2) compared to the Holocene Epoch. Higher abundances of G. ruber (pink) during the LGM were followed by a gradual decrease during the deglaciation and the early Holocene until it disappeared after around 8 kyr BP. Variability in the relative abundance of G. ruber (pink) was compared with mixed-layer and thermocline-dwelling species. The high abundance of G. ruber (pink), N. dutertrei and G. menardii during H2 and LGM in the eastern BoB suggests enhanced NE monsoon-driven vertical mixing, which may have facilitated nutrient transport from deeper layers to the thermocline and photic zone. The presence of G. ruber (pink) during glacial stages and the early Holocene demonstrates that it has not entirely disappeared from the Indian Ocean since 120 kyr BP and that its turnover may be driven by changing hydrographic conditions.
{"title":"Did Globigerinoides ruber (pink) disappear entirely from the Indian Ocean after 120 kyr BP?","authors":"Ammoose K. Jayan , A.V. Sijinkumar , Kaustubh Thirumalai , Lael Vetter , P. John Kurian , A. Prajith , Rajveer Sharma","doi":"10.1016/j.margeo.2025.107656","DOIUrl":"10.1016/j.margeo.2025.107656","url":null,"abstract":"<div><div>Extant since the Miocene, <em>Globigerinoides ruber</em> is a mixed-layer planktic foraminiferal species, cosmopolitan to the tropical–subtropical oceans. <em>Globigerinoides ruber</em> has multiple morphotypical variants with distinctive white and pink chromotypes. Today, the pink variety is exclusively found in the Atlantic Ocean and its nearby basins. For the past few decades, it was believed that pink-pigmented <em>G. ruber</em> disappeared from the Indo-Pacific Oceans at about 120 kyr BP. However, a recent study from the northwestern Bay of Bengal documented the presence of <em>G. ruber</em> (pink) in surface sediments. Hitherto, there was no evidence of <em>G. ruber</em> (pink) in downcore sediments from the Indian Ocean since 120 kyr BP. In this study, for the first time, we document the re-appearance of <em>G. ruber</em> (pink) from 30 to 8 kyr BP in gravity core MGS30/GC-03. The core was retrieved from the eastern BoB from a water depth of 1883 m, and its chronology was established using eight AMS radiocarbon dates. We observed high abundances of <em>G. ruber</em> (pink) during the Last Glacial Maximum (LGM) and Heinrich Event 1 and 2 (H1 and H2) compared to the Holocene Epoch. Higher abundances of <em>G. ruber</em> (pink) during the LGM were followed by a gradual decrease during the deglaciation and the early Holocene until it disappeared after around 8 kyr BP. Variability in the relative abundance of <em>G. ruber</em> (pink) was compared with mixed-layer and thermocline-dwelling species. The high abundance of <em>G. ruber</em> (pink), <em>N. dutertrei</em> and <em>G. menardii</em> during H2 and LGM in the eastern BoB suggests enhanced NE monsoon-driven vertical mixing, which may have facilitated nutrient transport from deeper layers to the thermocline and photic zone. The presence of <em>G. ruber</em> (pink) during glacial stages and the early Holocene demonstrates that it has not entirely disappeared from the Indian Ocean since 120 kyr BP and that its turnover may be driven by changing hydrographic conditions.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107656"},"PeriodicalIF":2.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-12DOI: 10.1016/j.margeo.2025.107657
Eleonora M. Fernández , Carla V. Spetter , Mariana Gentile , Diana M. Villagrán , Ana M. Martínez , Natalia S. Buzzi
Coastal wetlands, particularly tidal flats, play a crucial role in carbon sequestration and nutrient cycling in temperate environments. This study investigates the biochemical composition of sedimentary organic matter (SOM) in the tidal flats of Puerto Rosales (Bahía Blanca Estuary, Argentina), emphasizing the dual influences of natural processes and anthropogenic activities. Sampling was conducted seasonally (2014–2015) at two sites: ST1, an intertidal zone affected by untreated sewage discharge, and ST2, a supratidal zone dominated by microbial mats. Surface (0–5 mm) and subsurface (5–10 mm) sediment layers were analyzed to assess early diagenetic processes, SOM component and trophic status. Results indicated that the organic carbon (OC) in sediments was predominantly non-biogenic, with proteins as the major component of the labile fraction, influenced by seasonal phytoplankton blooms and urban discharges. While the tidal flat exhibited meso-oligotrophic to eutrophic conditions, refractory material dominated over labile fractions (proteins and carbohydrates). Additionally, distinct spatial and seasonal variations in SOM quality and composition, linked to redox conditions and organic detrital quality were observed.These findings underscore the ecological importance of Puerto Rosales tidal flats as dynamic systems for carbon storage and nutrient recycling. They highlight the need for sustainable management strategies to mitigate anthropogenic pressures and preserve the critical ecosystem functions of these coastal wetlands.
{"title":"Distribution of biochemical components in sedimentary organic matter of a Coastal Wetland: Anthropogenic and detrital influences","authors":"Eleonora M. Fernández , Carla V. Spetter , Mariana Gentile , Diana M. Villagrán , Ana M. Martínez , Natalia S. Buzzi","doi":"10.1016/j.margeo.2025.107657","DOIUrl":"10.1016/j.margeo.2025.107657","url":null,"abstract":"<div><div>Coastal wetlands, particularly tidal flats, play a crucial role in carbon sequestration and nutrient cycling in temperate environments. This study investigates the biochemical composition of sedimentary organic matter (SOM) in the tidal flats of Puerto Rosales (Bahía Blanca Estuary, Argentina), emphasizing the dual influences of natural processes and anthropogenic activities. Sampling was conducted seasonally (2014–2015) at two sites: ST1, an intertidal zone affected by untreated sewage discharge, and ST2, a supratidal zone dominated by microbial mats. Surface (0–5 mm) and subsurface (5–10 mm) sediment layers were analyzed to assess early diagenetic processes, SOM component and trophic status. Results indicated that the organic carbon (OC) in sediments was predominantly non-biogenic, with proteins as the major component of the labile fraction, influenced by seasonal phytoplankton blooms and urban discharges. While the tidal flat exhibited meso-oligotrophic to eutrophic conditions, refractory material dominated over labile fractions (proteins and carbohydrates). Additionally, distinct spatial and seasonal variations in SOM quality and composition, linked to redox conditions and organic detrital quality were observed.These findings underscore the ecological importance of Puerto Rosales tidal flats as dynamic systems for carbon storage and nutrient recycling. They highlight the need for sustainable management strategies to mitigate anthropogenic pressures and preserve the critical ecosystem functions of these coastal wetlands.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107657"},"PeriodicalIF":2.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-11DOI: 10.1016/j.margeo.2025.107646
P.H. Adema , J.T. Eggenhuisen , R. Silva Jacinto , N. Lagunova , A.I. Alwadhakhi , R. van der Woning , E. Miramontes
Turbidity currents transport sediment, organic carbon, nutrients, and pollutants from the continental shelf to the deep sea. They can flow over hundreds of kilometers through submarine canyons and channels. Along their trajectory, these flows may interact with contour currents, creating a mixed turbidite–contourite depositional system. Examples of such systems in the oceans exhibit a variety of channel shapes that are often asymmetrical. The effect of channel shape on turbidity currents and their interaction with contour currents remains unclear, yet understanding this could link flow characteristics to seafloor morphology. To this end, purely gravity-driven flows (turbidity currents) and combined flows were simulated in five different channel shapes (three symmetrical and two asymmetrical). The experiments show that firstly, combined flows have less steep vertical velocity gradients than purely gravity-driven experiments. The contour current advects momentum of the turbidity currents out of the channel onto the overbank, reducing the downslope flow velocity in the channel. Secondly, channel asymmetry results in asymmetrically overspilling flows, even without a contour current. Specifically, the overspilling flow is thicker and faster over the steep channel margin than over the gentle margin. Lastly, two types of secondary flow cells were formed. Channel cells, which are confined to the channel, and front cells, which form near stationary fronts in combined flows. These findings suggest that channel asymmetry alone is not diagnostic for inferring paleo-contour current directions. However, channel asymmetry can help to infer velocity distributions inside channels when only bathymetric data is available.
{"title":"Submarine channel shape controls combined turbidity current–contour current flow","authors":"P.H. Adema , J.T. Eggenhuisen , R. Silva Jacinto , N. Lagunova , A.I. Alwadhakhi , R. van der Woning , E. Miramontes","doi":"10.1016/j.margeo.2025.107646","DOIUrl":"10.1016/j.margeo.2025.107646","url":null,"abstract":"<div><div>Turbidity currents transport sediment, organic carbon, nutrients, and pollutants from the continental shelf to the deep sea. They can flow over hundreds of kilometers through submarine canyons and channels. Along their trajectory, these flows may interact with contour currents, creating a mixed turbidite–contourite depositional system. Examples of such systems in the oceans exhibit a variety of channel shapes that are often asymmetrical. The effect of channel shape on turbidity currents and their interaction with contour currents remains unclear, yet understanding this could link flow characteristics to seafloor morphology. To this end, purely gravity-driven flows (turbidity currents) and combined flows were simulated in five different channel shapes (three symmetrical and two asymmetrical). The experiments show that firstly, combined flows have less steep vertical velocity gradients than purely gravity-driven experiments. The contour current advects momentum of the turbidity currents out of the channel onto the overbank, reducing the downslope flow velocity in the channel. Secondly, channel asymmetry results in asymmetrically overspilling flows, even without a contour current. Specifically, the overspilling flow is thicker and faster over the steep channel margin than over the gentle margin. Lastly, two types of secondary flow cells were formed. Channel cells, which are confined to the channel, and front cells, which form near stationary fronts in combined flows. These findings suggest that channel asymmetry alone is not diagnostic for inferring paleo-contour current directions. However, channel asymmetry can help to infer velocity distributions inside channels when only bathymetric data is available.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107646"},"PeriodicalIF":2.2,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-06DOI: 10.1016/j.margeo.2025.107655
Karol Zglinicki , Michał Pilaszkiewicz , Agnieszka Wrzosek , Krzysztof Szamałek , Szymon Uścinowicz , Kazimierz Szefler , Jarosław Nowak , Paweł Bylina
Studies of polymetallic nodules in oceans and shelf seas, including the Baltic Sea, have a long history. However, detailed mineralogical and geochemical data for nodules from the southern Polish Baltic region are limited in comparison to data from oceans and other regions of the Baltic Sea. This study fills gaps in knowledge regarding the mineralogical and chemical composition of nodules from the southern Baltic. The research concerned nodules sampled from two locations in the Polish Exclusive Economic Zone (EEZ), namely seabed elevations between the Słupsk Furrow and Gdańsk Basin (P1) and between Bornholm Basin and Słupsk Furrow (P2), areas known for their abundance of nodules. The following analytical methods were used: X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS), inductively coupled plasma emission spectroscopy/optical emission spectroscopy (ICP-MS/OES) and electron probe microanalysis (EPMA). The nodules comprise a mixture of terrigenous minerals and autochthonous manganese oxides, represented by birnessite, vernadite (7 Å and 10 Å varieties) and iron oxyhydroxides, mainly goethite. Depending on the location, the samples reveal varying chemical compositions. Nodules from sampling site P1 are characterized by a moderate Fe content, averaging 10.68 wt%, and low Mn content, averaging 3.04 wt%, with an Mn/Fe ratio ranging from 0.12 to 0.43. These nodules have low concentrations of ∑Ni + Co + Cu (104.5 to 238.6 ppm) and other economically significant metals such as Zn (78.0–140 ppm), Mo (14.9–77.8 ppm), and V (80.0–187.0 ppm). These nodules exhibit pronounced lithium enrichment, with concentrations ranging from 72.1 to 444.6 ppm. On the other hand, at sampling site P2, the average parameters are higher, i.e., Fe content 12.30 wt%, Mn 10.50 wt%, and a Mn/Fe ratio of 0.50 to 1.25. The concentration of ∑Ni + Co + Cu ranges from 159.0 to 530.0 ppm, with elevated contents of Zn (104.0–238.0 ppm), Mo (26.0–174.0 ppm), and V (118.0–249.0 ppm). Lithium content is low (max. 145.4 ppm). In field P1, the growth rates ranged from 2.21 to 3.47 mm/1000 years, while in field P2, the growth rates ranged from 6.50 to 21.00 mm/1000 years. The genesis of the nodules indicates mixed diagenetic‑hydrogenetic processes probably influenced by hydrothermal activity. Although classical hydrothermal processes do not occur in the Baltic Sea, the impact of deep-seated fluids may significantly shape the formation of the nodules.
{"title":"Fe-nodules from the southern Baltic Sea: Morphology, mineralogy and geochemistry","authors":"Karol Zglinicki , Michał Pilaszkiewicz , Agnieszka Wrzosek , Krzysztof Szamałek , Szymon Uścinowicz , Kazimierz Szefler , Jarosław Nowak , Paweł Bylina","doi":"10.1016/j.margeo.2025.107655","DOIUrl":"10.1016/j.margeo.2025.107655","url":null,"abstract":"<div><div>Studies of polymetallic nodules in oceans and shelf seas, including the Baltic Sea, have a long history. However, detailed mineralogical and geochemical data for nodules from the southern Polish Baltic region are limited in comparison to data from oceans and other regions of the Baltic Sea. This study fills gaps in knowledge regarding the mineralogical and chemical composition of nodules from the southern Baltic. The research concerned nodules sampled from two locations in the Polish Exclusive Economic Zone (EEZ), namely seabed elevations between the Słupsk Furrow and Gdańsk Basin (P1) and between Bornholm Basin and Słupsk Furrow (P2), areas known for their abundance of nodules. The following analytical methods were used: X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS), inductively coupled plasma emission spectroscopy/optical emission spectroscopy (ICP-MS/OES) and electron probe microanalysis (EPMA). The nodules comprise a mixture of terrigenous minerals and autochthonous manganese oxides, represented by birnessite, vernadite (7 Å and 10 Å varieties) and iron oxyhydroxides, mainly goethite. Depending on the location, the samples reveal varying chemical compositions. Nodules from sampling site P1 are characterized by a moderate Fe content, averaging 10.68 wt%, and low Mn content, averaging 3.04 wt%, with an Mn/Fe ratio ranging from 0.12 to 0.43. These nodules have low concentrations of ∑Ni + Co + Cu (104.5 to 238.6 ppm) and other economically significant metals such as Zn (78.0–140 ppm), Mo (14.9–77.8 ppm), and V (80.0–187.0 ppm). These nodules exhibit pronounced lithium enrichment, with concentrations ranging from 72.1 to 444.6 ppm. On the other hand, at sampling site P2, the average parameters are higher, i.e., Fe content 12.30 wt%, Mn 10.50 wt%, and a Mn/Fe ratio of 0.50 to 1.25. The concentration of ∑Ni + Co + Cu ranges from 159.0 to 530.0 ppm, with elevated contents of Zn (104.0–238.0 ppm), Mo (26.0–174.0 ppm), and V (118.0–249.0 ppm). Lithium content is low (max. 145.4 ppm). In field P1, the growth rates ranged from 2.21 to 3.47 mm/1000 years, while in field P2, the growth rates ranged from 6.50 to 21.00 mm/1000 years. The genesis of the nodules indicates mixed diagenetic‑hydrogenetic processes probably influenced by hydrothermal activity. Although classical hydrothermal processes do not occur in the Baltic Sea, the impact of deep-seated fluids may significantly shape the formation of the nodules.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107655"},"PeriodicalIF":2.2,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-05DOI: 10.1016/j.margeo.2025.107647
Jianfeng Su , Yijing Wu , Daidu Fan
Coastal wetlands are essential yet vulnerable carbon sinks; however, the impacts of vegetation replacement on carbon dynamics remain less understood. This study investigates the sources, burial rates, and historical trends of sedimentary organic carbon (OC) across various wetland types, including mangroves, Spartina alterniflora (S. A.), and barren tidal flats in Sansha Bay, Fujian Province, Southeast China. We analyzed sediment cores for geochemical (TOC, TN, δ13C) and radionuclide (210Pb, 137Cs) proxies. Our results reveal that riverine inputs are the primary sources of OC, contributing 51–75 % of the total. The mangrove ecosystem exhibits the highest OC burial rate at163 ± 49 g/m2/yr, followed by the S. A. marshland at 115 ± 16 g/m2/yr, and barren flats at 69 ± 13 g/m2/yr. However, human interventions, particularly land reclamation and the invasion of S. A., have resulted in a 13.64 % decrease in the bay-wide OC burial rate from 1999 to 2018. While S. A. enhances local carbon sequestration, its invasion disrupts mangrove ecosystems and destabilizes existing carbon pools. This study underscores the dual impact of vegetation changes on coastal carbon dynamics: invasive species may temporarily enhance OC burial rates but ultimately undermine long-term ecosystem resilience. To maintain blue carbon functions, we advocate prioritizing mangrove conservation, restoring degraded wetlands, and curbing the spread of S. A. These findings provide valuable insights for balancing carbon mitigation efforts and biodiversity conservation in rapidly changing coastal environments.
{"title":"Impacts of vegetation replacement on organic carbon burial in coastal wetlands of Sansha Bay, Southeast China","authors":"Jianfeng Su , Yijing Wu , Daidu Fan","doi":"10.1016/j.margeo.2025.107647","DOIUrl":"10.1016/j.margeo.2025.107647","url":null,"abstract":"<div><div>Coastal wetlands are essential yet vulnerable carbon sinks; however, the impacts of vegetation replacement on carbon dynamics remain less understood. This study investigates the sources, burial rates, and historical trends of sedimentary organic carbon (OC) across various wetland types, including mangroves, <em>Spartina alterniflora</em> (<em>S. A.</em>), and barren tidal flats in Sansha Bay, Fujian Province, Southeast China. We analyzed sediment cores for geochemical (TOC, TN, δ<sup>13</sup>C) and radionuclide (<sup>210</sup>Pb, <sup>137</sup>Cs) proxies. Our results reveal that riverine inputs are the primary sources of OC, contributing 51–75 % of the total. The mangrove ecosystem exhibits the highest OC burial rate at163 ± 49 g/m<sup>2</sup>/yr, followed by the <em>S. A.</em> marshland at 115 ± 16 g/m<sup>2</sup>/yr, and barren flats at 69 ± 13 g/m<sup>2</sup>/yr. However, human interventions, particularly land reclamation and the invasion of <em>S. A.</em>, have resulted in a 13.64 % decrease in the bay-wide OC burial rate from 1999 to 2018. While <em>S. A.</em> enhances local carbon sequestration, its invasion disrupts mangrove ecosystems and destabilizes existing carbon pools. This study underscores the dual impact of vegetation changes on coastal carbon dynamics: invasive species may temporarily enhance OC burial rates but ultimately undermine long-term ecosystem resilience. To maintain blue carbon functions, we advocate prioritizing mangrove conservation, restoring degraded wetlands, and curbing the spread of <em>S. A.</em> These findings provide valuable insights for balancing carbon mitigation efforts and biodiversity conservation in rapidly changing coastal environments.</div></div>","PeriodicalId":18229,"journal":{"name":"Marine Geology","volume":"490 ","pages":"Article 107647"},"PeriodicalIF":2.2,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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