Paleoceanography and Paleoclimatology最新文献_第5页

Spatial and Temporal Patterns in Petrogenic Organic Carbon Mobilization During the Paleocene‐Eocene Thermal Maximum 古新世-始新世热极盛时期成岩有机碳移动的空间和时间模式

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-31 DOI: 10.1029/2023pa004773

E. Hollingsworth, F. Elling, Marcus Peter, Sebastian Badger, R. Pancost, A. Dickson, R. Rees-Owen, N. Papadomanolaki, Ann Pearson, A. Sluijs, K. Freeman, A. Baczynski, Gavin L. Foster, J. Whiteside, G. Inglis, M. Badger, Paleoceanography Paleoclimatology

{"title":"Spatial and Temporal Patterns in Petrogenic Organic Carbon Mobilization During the Paleocene‐Eocene Thermal Maximum","authors":"E. Hollingsworth, F. Elling, Marcus Peter, Sebastian Badger, R. Pancost, A. Dickson, R. Rees-Owen, N. Papadomanolaki, Ann Pearson, A. Sluijs, K. Freeman, A. Baczynski, Gavin L. Foster, J. Whiteside, G. Inglis, M. Badger, Paleoceanography Paleoclimatology","doi":"10.1029/2023pa004773","DOIUrl":"https://doi.org/10.1029/2023pa004773","url":null,"abstract":"The Paleocene‐Eocene Thermal Maximum (PETM) was a transient global warming event and is recognized in the geologic record by a prolonged negative carbon isotope excursion (CIE). The onset of the CIE was due to a rapid influx of 13C‐depleted carbon into the ocean‐atmosphere system. However, the mechanisms required to sustain the negative CIE remains unclear. Enhanced mobilization and oxidation of petrogenic organic carbon (OCpetro) has been invoked to explain elevated atmospheric carbon dioxide concentrations after the onset of the CIE. However, existing evidence is limited to the mid‐latitudes and subtropics. Here, we determine whether: (a) enhanced mobilization and subsequent burial of OCpetro in marine sediments was a global phenomenon; and (b) whether it occurred throughout the PETM. To achieve this, we utilize a lipid biomarker approach to trace and quantify OCpetro burial in a global compilation of PETM‐aged shallow marine sites (n = 7, including five new sites). Our results confirm that OCpetro mass accumulation rates (MARs) increased within the subtropics and mid‐latitudes during the PETM, consistent with evidence of higher physical erosion rates and intense episodic rainfall events. High‐latitude sites do not exhibit drastic changes in the source of organic carbon during the PETM and OCpetro MARs increase slightly or remain stable, perhaps due a more stable hydrological regime. Crucially, we also demonstrate that OCpetro MARs remained elevated during the recovery phase of the PETM. Although OCpetro oxidation was likely an important positive feedback mechanism throughout the PETM, we show that this feedback was both spatially and temporally variable.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140471937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Biomarker Reconstruction of a High‐Latitude Late Paleocene to Early Eocene Coal Swamp Environment Across the PETM and ETM‐2 (Ellesmere Island, Arctic Canada) 跨越 PETM 和 ETM-2 的高纬度晚古新世至早始新世煤沼环境的生物标志物重建（加拿大北极地区埃尔斯米尔岛）

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-30 DOI: 10.1029/2023pa004712

M. Blumenberg, B. Naafs, A. Lückge, V. Lauretano, E. Schefuß, J. M. Galloway, G. Scheeder, L. Reinhardt

{"title":"Biomarker Reconstruction of a High‐Latitude Late Paleocene to Early Eocene Coal Swamp Environment Across the PETM and ETM‐2 (Ellesmere Island, Arctic Canada)","authors":"M. Blumenberg, B. Naafs, A. Lückge, V. Lauretano, E. Schefuß, J. M. Galloway, G. Scheeder, L. Reinhardt","doi":"10.1029/2023pa004712","DOIUrl":"https://doi.org/10.1029/2023pa004712","url":null,"abstract":"The Paleocene‐Eocene Thermal Maximum (PETM) and early Eocene hyperthermal events were characterized by a Hothouse climate state. Our understanding of the climatic impact of these hyperthermals is currently biased toward marine settings and the mid‐latitudes. Here we present organic geochemical data from Stenkul Fiord, Ellesmere Island, Arctic Canada. This organic rich formation was deposited in a high northern latitude wetland setting during the late Paleocene to early Eocene, spanning the PETM and subsequent ETM‐2 hyperthermals. Biomarker data (e.g., diterpenoids), combined with published palynological data from the site, indicate Cupressaceae‐dominated vegetation. Biomarkers suggest that land plant composition remained fairly unchanged across the two hyperthermal events. Increases in abundance and 13C‐depletion of hopanoid biomarkers (minima <−50‰ (VPDB)) highlight periods of enhanced bacterial methane consumption, particularly during the PETM. However, periods of low hopanoid δ13C values were also found outside the hyperthermal intervals. Relatively low δ2H values of higher plant n‐alkanes (average δ2H values of n‐C25, n‐C27, n‐C29 ∼ −230 to −270‰ (SMOW)) indicate that deposition formed during times with enhanced precipitation. The wettest intervals, as identified by the lowest δ2H n‐alkane values, contain high abundances of hopenes, indicating enhanced bacterial turnover. At Stenkul Fiord, high temperatures and CO2 concentrations likely fostered the growth of widespread wetland forests that became a CO2 sink and may have played an important role in carbon drawdown during the Early Paleogene.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140482038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Brazil Margin Stable Isotope Profiles for the Last Glacial Cycle: Implications for Watermass Geometry and Oceanic Carbon Storage 最后冰川周期的巴西边缘稳定同位素剖面：水团几何学和海洋碳储存的含义

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-01 DOI: 10.1029/2023pa004635

A. B. Shub, D. Lund, D. Oppo, M. Garity

{"title":"Brazil Margin Stable Isotope Profiles for the Last Glacial Cycle: Implications for Watermass Geometry and Oceanic Carbon Storage","authors":"A. B. Shub, D. Lund, D. Oppo, M. Garity","doi":"10.1029/2023pa004635","DOIUrl":"https://doi.org/10.1029/2023pa004635","url":null,"abstract":"Vertical profiles of benthic foraminiferal oxygen and carbon isotopes (δ18O and δ13C) imply the volume of southern source water (SSW) in the Atlantic basin expanded during the Last Glacial Maximum. Shoaling of the boundary between SSW and northern source water (NSW) may reduce mixing between the two watermasses, thereby isolating SSW and enhancing its ability to store carbon during glacial intervals. Here we test this hypothesis using profiles of δ18O and δ13C from the Brazil Margin spanning the last glacial cycle (0–150 ka). Shoaling of the SSW‐NSW boundary occurred during Marine Isotope Stage (MIS) 2, 4, and 6, consistent with expansion of SSW and greater carbon sequestration in the abyss. But the watermass boundary also shoaled during MIS 5e, when atmospheric CO2 levels were comparable to MIS 1. Additionally, we find there was little change in watermass structure across the MIS 5e‐d transition, the first major decline in CO2 of the last glacial cycle. Thus, the overall pattern in glacial‐interglacial geometry is inconsistent with watermass mixing acting as a primary control on atmospheric pCO2. We also find that δ13C values for MIS 5e are systematically lower than MIS 1, with the largest difference (∼1‰) occurring in the upper water column. Low δ13C during MIS 5e was most likely due to a long‐term imbalance in weathering and deposition of calcium carbonate or input of 13C‐depleted carbon from a reservoir external to the ocean‐atmosphere system.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139632387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Detecting Paleoclimate Transitions With Laplacian Eigenmaps of Recurrence Matrices (LERM) 利用复现矩阵的拉普拉斯特征图（LERM）检测古气候转变

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-01 DOI: 10.1029/2023pa004700

Alexander James, J. Emile‐Geay, Nishant Malik, D. Khider

{"title":"Detecting Paleoclimate Transitions With Laplacian Eigenmaps of Recurrence Matrices (LERM)","authors":"Alexander James, J. Emile‐Geay, Nishant Malik, D. Khider","doi":"10.1029/2023pa004700","DOIUrl":"https://doi.org/10.1029/2023pa004700","url":null,"abstract":"Paleoclimate records can be considered low‐dimensional projections of the climate system that generated them. Understanding what these projections tell us about past climates, and changes in their dynamics, is a main goal of time series analysis on such records. Laplacian eigenmaps of recurrence matrices (LERM) is a novel technique using univariate paleoclimate time series data to indicate when notable shifts in dynamics have occurred. LERM leverages time delay embedding to construct a manifold that is mappable to the attractor of the climate system; this manifold can then be analyzed for significant dynamical transitions. Through numerical experiments with observed and synthetic data, LERM is applied to detect both gradual and abrupt regime transitions. Our paragon for gradual transitions is the Mid‐Pleistocene Transition (MPT). We show that LERM can robustly detect gradual MPT‐like transitions for sufficiently high signal‐to‐noise (S/N) ratios, though with a time lag related to the embedding process. Our paragon of abrupt transitions is the “8.2 ka” event; we find that LERM is generally robust at detecting 8.2 ka‐like transitions for sufficiently high S/N ratios, though edge effects become more influential. We conclude that LERM can usefully detect dynamical transitions in paleogeoscientific time series, with the caveat that false positive rates are high when dynamical transitions are not present, suggesting the importance of using multiple records to confirm the robustness of transitions. We share an open‐source Python package to facilitate the use of LERM in paleoclimatology and paleoceanography.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139395963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Summer and Autumn Insolation as the Pacemaker of Surface Wind and Precipitation Dynamics Over Tropical Indian Ocean During the Holocene: Insights From Paleoproductivity Records and Paleoclimate Simulations 夏秋日照是全新世热带印度洋海面风和降水动力学的起搏器：古生产率记录和古气候模拟的启示

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-01 DOI: 10.1029/2023pa004786

Xinquan Zhou, Stéphanie Duchamp-Alphonse, Franck Bassinot, Chuanlian Liu

{"title":"Summer and Autumn Insolation as the Pacemaker of Surface Wind and Precipitation Dynamics Over Tropical Indian Ocean During the Holocene: Insights From Paleoproductivity Records and Paleoclimate Simulations","authors":"Xinquan Zhou, Stéphanie Duchamp-Alphonse, Franck Bassinot, Chuanlian Liu","doi":"10.1029/2023pa004786","DOIUrl":"https://doi.org/10.1029/2023pa004786","url":null,"abstract":"Insolation is the engine of monsoon and Walker circulations over the tropical Indian Ocean. Here, we present Holocene coccolith‐related net primary productivity (NPP) signals from two sediment cores retrieved in the wind‐driven coastal upwelling systems off southern India and southern Sumatra. Upwelling‐induced NPP is enhanced during summer and autumn and is a powerful tool to reconstruct atmospheric features at a seasonal scale. Our records indicate that during summer and autumn, westerly winds off southern India strengthened from the early‐Holocene (EH) to late‐Holocene (LH), while southeasterly winds off southern Sumatra strengthened from the EH to mid‐Holocene (MH) and weakened from the MH to LH. Comparisons with previous paleoclimate records and simulations, allow us to confirm such wind patterns at a regional scale and identify distinct atmospheric features associated to insolation before and after the MH. From the EH to MH, as the insolation in the Northern Hemisphere weakens during summer and strengthens during autumn, the equatorial Indian Ocean is characterized by more vigorous Walker and monsoon circulations in summer and autumn, respectively. From the MH to LH, as the insolation weakens in the Northern Hemisphere during summer and over the equator during autumn, the equatorial Indian Ocean is influenced by a general reinforcement of the Walker circulation during both seasons, a feature that we relate to a modern negative IOD‐like mode. The changes in wind result in increasing precipitation over Indonesia and India from EH to MH and over Indonesia from MH to LH as India is getting dryer.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139393611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Ocean Oxygen, Preformed Nutrients, and the Cause of the Lower Carbon Dioxide Concentration in the Atmosphere of the Last Glacial Maximum 海洋氧气、预形成营养物质以及最后冰川极盛时期大气中二氧化碳浓度降低的原因

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-01 DOI: 10.1029/2023pa004775

D. Sigman, M. Hain

{"title":"Ocean Oxygen, Preformed Nutrients, and the Cause of the Lower Carbon Dioxide Concentration in the Atmosphere of the Last Glacial Maximum","authors":"D. Sigman, M. Hain","doi":"10.1029/2023pa004775","DOIUrl":"https://doi.org/10.1029/2023pa004775","url":null,"abstract":"All else equal, if the ocean's “biological [carbon] pump” strengthens, the dissolved oxygen (O2) content of the ocean interior declines. Confidence is now high that the ocean interior as a whole contained less oxygen during the ice ages. This is strong evidence that the ocean's biological pump stored more carbon in the ocean interior during the ice ages, providing the core of an explanation for the lower atmospheric carbon dioxide (CO2) concentrations of the ice ages. Vollmer et al. (2022, https://doi.org/10.1029/2021PA004339) combine proxies for the oxygen and nutrient content of bottom waters to show that the ocean nutrient reservoir was more completely harnessed by the biological pump during the Last Glacial Maximum, with an increase in the proportion of dissolved nutrients in the ocean interior that were “regenerated” (transported as sinking organic matter from the ocean surface to the interior) rather than “preformed” (transported to the interior as dissolved nutrients by ocean circulation). This points to changes in the Southern Ocean, the dominant source of preformed nutrients in the modern ocean, with an apparent additional contribution from a decline in the preformed nutrient content of North Atlantic‐formed interior water. Vollmer et al. also find a lack of LGM‐to‐Holocene difference in the preformed 13C/12C ratio of dissolved inorganic carbon. This finding may allow future studies to resolve which of the proposed Southern Ocean mechanisms was most responsible for enhanced ocean CO2 storage during the ice ages: (a) coupled changes in ocean circulation and biological productivity, or (b) physical limitations on air‐sea gas exchange.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139639010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Biomarker Evidence for an MIS M2 Glacial‐Pluvial in the Mojave Desert Before Warming and Drying in the Late Pliocene 莫哈韦沙漠在上新世晚期变暖和干燥之前的 MIS M2 冰川-河流生物标志证据

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2024-01-01 DOI: 10.1029/2023pa004687

M. Peaple, Tripti Bhattacharya, J. Tierney, Jeffrey R. Knott, T. Lowenstein, S. Feakins

{"title":"Biomarker Evidence for an MIS M2 Glacial‐Pluvial in the Mojave Desert Before Warming and Drying in the Late Pliocene","authors":"M. Peaple, Tripti Bhattacharya, J. Tierney, Jeffrey R. Knott, T. Lowenstein, S. Feakins","doi":"10.1029/2023pa004687","DOIUrl":"https://doi.org/10.1029/2023pa004687","url":null,"abstract":"Ancient lake deposits in the Mojave Desert indicate that the water cycle in this currently dry place was radically different under past climates. Here we revisit a 700 m core drilled 55 years ago from Searles Valley, California, that recovered evidence for a lacustrine phase during the late Pliocene. We update the paleomagnetic age model and extract new biomarker evidence for climatic conditions from lacustrine deposits (3.373–2.706 Ma). The MBT′5Me temperature proxy detects present‐day conditions (21 ± 3°C, n = 2) initially, followed by warmer‐than‐present conditions (25 ± 3°C, n = 17) starting at 3.268 and ending at 2.734 Ma. Bacterial and archeal biomarkers reveal lake salinity increased after 3.268 Ma likely reflecting increased evaporation in response to higher temperatures. The δ13C values of plant waxes (−30.7 ± 1.4‰, n = 28) are consistent with local C3 taxa, likely expanded conifer woodlands during the pluvial with less C4 than the Pleistocene. δD values (−174 ± 5‰, n = 25) of plant waxes indicate precipitation δD values (−89 ± 5‰, n = 25) in the late Pliocene are within the same range as the late Pleistocene precipitation δD. Microbial biomarkers identify a deep, freshwater lake and a cooling that corresponds to the onset of major Northern Hemisphere glaciation at marine isotope stage marine isotope stages M2 (3.3 Ma). A more saline lake persisted for ∼0.6 Ma across the subsequent warmth of the late Pliocene (3.268–2.734 Ma) before the lake desiccated at the Pleistocene intensification of Northern Hemisphere Glaciation.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139395028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Pacific‐Driven Salinity Variability in the Timor Passage Since 1777 1777 年以来太平洋驱动的帝汶海峡盐度变化

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2023-12-01 DOI: 10.1029/2023pa004702

Elizabeth W. Patterson, Julia E. Cole, K. Dyez, L. Vetter, Janice M. Lough

{"title":"Pacific‐Driven Salinity Variability in the Timor Passage Since 1777","authors":"Elizabeth W. Patterson, Julia E. Cole, K. Dyez, L. Vetter, Janice M. Lough","doi":"10.1029/2023pa004702","DOIUrl":"https://doi.org/10.1029/2023pa004702","url":null,"abstract":"Salinity in the Indonesian seas integrates regional oceanographic and atmospheric processes, such as Indonesian Throughflow (ITF) and monsoon rainfall. Here we present a multicentury (1777–1983) δ18O coral record from Nightcliff Reef, located in the Timor Passage off the coast of northern Australia, which we use to infer local salinity change. We show that Australian monsoon rainfall and ITF influence salinity at the study site. These reconstructed salinity changes in the Timor Passage correlate with changes in Pacific sea surface temperature (SST) modes, including the El Niño Southern Oscillation (ENSO) and the Interdecadal Pacific Oscillation (IPO). While environmental stress creates challenging conditions for coral growth, this record particularly tracks the central Pacific signature of ENSO‐driven interannual variability, in agreement with reconstructions of rainfall across northern Australia. The strength of interannual variance in the record follows fluctuations in other local ENSO‐sensitive rainfall reconstructions, demonstrating a strong regional ENSO signature. However, this regional pattern differs from variance in composite ENSO reconstructions, suggesting that the multi‐site nature of these reconstructions may create biases. Salinity variability on decadal and longer time scales occurs throughout the record. Some of these oscillations are consistent with other ITF‐sensitive coral records. Our new salinity record adds a strongly Pacific‐sensitive record to the existing suite of regional paleoclimate reconstructions. Relationships among these records highlight the complexity of salinity in the Indonesian seas and the controls on its variability.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138623932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

Evolution of Oceanography of the Central Northwest Pacific Over the Past 10 Million Years With Focus on Late Miocene Global Cooling 过去 1000 万年西北太平洋中部海洋学的演变，聚焦中新世晚期全球变冷

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2023-12-01 DOI: 10.1029/2023pa004789

Kenji M. Matsuzaki

{"title":"Evolution of Oceanography of the Central Northwest Pacific Over the Past 10 Million Years With Focus on Late Miocene Global Cooling","authors":"Kenji M. Matsuzaki","doi":"10.1029/2023pa004789","DOIUrl":"https://doi.org/10.1029/2023pa004789","url":null,"abstract":"Since the middle Miocene climatic transition, the Earth's climate has steadily cooled. The late Miocene global cooling (LMGC) and the Northern Hemisphere Glaciation (NHG) were two key cooling events occurring during this time. To better understand the mechanisms underlying these cooling events, changes in radiolarian microfossil assemblages were examined in this study, aiming at the reconstructing of oceanographic changes that have occurred at Ocean Drilling Program site 1208 during the last 10 million years. Sea surface temperatures (SSTs) were reconstructed based on radiolarian species that were extant 0–10 million years ago. Reconstructed SSTs were then compared with previously published alkenone‐based SSTs at site 1208, and it was found that overall, using SSTs based only on extant radiolarian species yielded a correct record for the last 10 million years. However, large discrepancies were observed between radiolarian‐ and alkenone‐based SSTs during LMGC and the NHG. These discrepancies were attributed to the sustained influence of subsurface water (at depths from ∼50 to 100 m) on assemblages of radiolarians during extreme cooling events. Relative abundances of other radiolarian groups indicated that during LMGC, there was a reorganization of the regional oceanography that probably weakened the Pacific meridional overturning circulation, increased the meridional temperature gradient, and caused a southward migration of the subtropical front. Probably, the North Pacific intermediate water expanded southeastward during NHG.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139021793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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

A Warming Southern Gulf of Mexico: Reconstruction of Anthropogenic Environmental Changes From a Siderastrea siderea Coral on the Northern Coast of Cuba 墨西哥湾南部变暖：从古巴北部海岸的 Siderastrea siderea 珊瑚重建人为环境变化

IF 3.5 2区地球科学

Paleoceanography and Paleoclimatology Pub Date : 2023-12-01 DOI: 10.1029/2023pa004717

M. Harbott, H. C. Wu, H. Kuhnert, C. Jimenez, P. González‐Díaz, T. Rixen

{"title":"A Warming Southern Gulf of Mexico: Reconstruction of Anthropogenic Environmental Changes From a Siderastrea siderea Coral on the Northern Coast of Cuba","authors":"M. Harbott, H. C. Wu, H. Kuhnert, C. Jimenez, P. González‐Díaz, T. Rixen","doi":"10.1029/2023pa004717","DOIUrl":"https://doi.org/10.1029/2023pa004717","url":null,"abstract":"The Gulf of Mexico is a vital region for the Atlantic Meridional Overturning Circulation (AMOC), that fuels the exchange of heat between the tropics and the polar regions. A weakening of the AMOC would have dire consequences for the planet. First observations and ocean models show that this process has already started. Very limited knowledge of the components that are part of the AMOC such as the Loop Current (LC) make it difficult to understand its dynamics as well as changes in strength or temperature since the onset of the Industrial Revolution. Currently, there are no continuous in situ sea surface temperature or salinity measurements for the southeastern Gulf of Mexico or reconstruction attempts for this region, showing the necessity for high‐resolution climate archives. A Siderastrea siderea coral core was retrieved from the northwestern Cuban coast and used as a sub‐seasonally resolved sea surface temperature and hydroclimate archive. The approach is based on skeletal δ18O, and trace and minor element contents show an increase in temperature over 160 years since 1845 of 2.6–3.3°C. A possible stagnation of the warming trend set in after the 1980s, indicating a potential weakening of the Loop Current. Impacts in sea surface salinity such as El Niño events in the Pacific region can still be detected in the Gulf of Mexico as decreases in salinity in 1998 from the reconstructed δ18OSW coral record. In situ measurements remain crucial to understand the dynamics in the LC and its influence on the AMOC.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138989007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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