Yulong Guan, Zhaoxia Jiang, Sanzhong Li, Liang Chen, Yang Liu, Yuying Chen, Yuzhen Zhang, Long Chen, Liang Zhou, Zhengxin Yin
The terrestrial magnetic minerals of marine sediments are utilized to track the climatic changes in the source area and the dynamic characteristics of sedimentation processes. However, due to the varied source‐to‐sink environments, the magnetic response to ambient climate cannot be generalized. Here, we conducted systematic environmental magnetic analyses on core CJ04‐50 from the Ninetyeast Ridge and investigated its magnetic response to source‐to‐sink environmental changes. Core CJ04‐50 covers the last 60 Kyr based on accelerator mass spectrometry (AMS) 14C dating and the relative paleointensity (RPI) record. Rare earth element (REE) results suggest that the terrestrial materials are fed by the Ganges‐Brahmaputra (G‐B) and Irrawaddy/Indo‐Burma Ranges. High/low magnetic mineral content corresponds to strong/weak terristrial input during the cold/warm period. This pattern differs from that in the East Asian marginal seas, which have a high magnetic mineral content in warm periods. It might be attributed to the heavier Indian summer monsoon (ISM) precipitation than that of East Asian summer monsoon. Excessive moisture (>1,500 mm/year) would not favor the formation and preservation of magnetic minerals in the source area during interglacials. By contrast, the enhanced physical weathering during glacials results in more magnetic contributions. A significant local magnetite dissolution occurred at the layer of Middle MIS 3, which may be caused by the non‐steady state diagenesis following deposition.
{"title":"Magnetic Response to the Source‐To‐Sink Environmental Changes in the Bay of Bengal Since ∼60 ka","authors":"Yulong Guan, Zhaoxia Jiang, Sanzhong Li, Liang Chen, Yang Liu, Yuying Chen, Yuzhen Zhang, Long Chen, Liang Zhou, Zhengxin Yin","doi":"10.1029/2024pa004857","DOIUrl":"https://doi.org/10.1029/2024pa004857","url":null,"abstract":"The terrestrial magnetic minerals of marine sediments are utilized to track the climatic changes in the source area and the dynamic characteristics of sedimentation processes. However, due to the varied source‐to‐sink environments, the magnetic response to ambient climate cannot be generalized. Here, we conducted systematic environmental magnetic analyses on core CJ04‐50 from the Ninetyeast Ridge and investigated its magnetic response to source‐to‐sink environmental changes. Core CJ04‐50 covers the last 60 Kyr based on accelerator mass spectrometry (AMS) 14C dating and the relative paleointensity (RPI) record. Rare earth element (REE) results suggest that the terrestrial materials are fed by the Ganges‐Brahmaputra (G‐B) and Irrawaddy/Indo‐Burma Ranges. High/low magnetic mineral content corresponds to strong/weak terristrial input during the cold/warm period. This pattern differs from that in the East Asian marginal seas, which have a high magnetic mineral content in warm periods. It might be attributed to the heavier Indian summer monsoon (ISM) precipitation than that of East Asian summer monsoon. Excessive moisture (>1,500 mm/year) would not favor the formation and preservation of magnetic minerals in the source area during interglacials. By contrast, the enhanced physical weathering during glacials results in more magnetic contributions. A significant local magnetite dissolution occurred at the layer of Middle MIS 3, which may be caused by the non‐steady state diagenesis following deposition.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141043507","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}
D. R. Munday, I. Sauermilch, A. Klocker, J. M. Whittaker
Ambiguity over the Eocene opening times of the Tasman Gateway and Drake Passage makes it difficult to determine the initiation time of the Antarctic Circumpolar Current. If the Tasman Gateway opened later than Drake Passage, then Australia may have prevented the proto‐ACC from forming. Recent modeling results have shown that only a relatively weak circumpolar transport results under Eocene surface forcing. This leads to warm and buoyant coastal water around Antarctica, which may impede the formation of deep waters and convective processes. This suggests that a change in deep water formation might be required to increase the density contrast across the Southern Ocean and increase circumpolar transport. Here we use a simple reduced gravity model with two basins, to represent the Atlantic and the Pacific. This fixes the density difference between surface and deep water and allows us to isolate the impact of deep water formation on circumpolar transport. With no obstacle on the southern boundary the circumpolar current increases its transport from 82.3 to 270.0 Sv with deep water formation. Placing an Antipodean landmass on the southern boundary reduces this transport as the landmass increases in size. However, circumpolar flow north of this landmass remains a possibility even without deep water formation. Weak circumpolar transport continues until the basin is completely blocked by the Antipodes. When the Antipodes is instead allowed to split from the southern boundary, circumpolar transport recovers to its unobstructed value. Flow rapidly switches to south of the Antipodes when the gateway is narrow.
{"title":"Impact of Deep Water Formation on Antarctic Circumpolar Transport During Gateway Opening","authors":"D. R. Munday, I. Sauermilch, A. Klocker, J. M. Whittaker","doi":"10.1029/2022pa004605","DOIUrl":"https://doi.org/10.1029/2022pa004605","url":null,"abstract":"Ambiguity over the Eocene opening times of the Tasman Gateway and Drake Passage makes it difficult to determine the initiation time of the Antarctic Circumpolar Current. If the Tasman Gateway opened later than Drake Passage, then Australia may have prevented the proto‐ACC from forming. Recent modeling results have shown that only a relatively weak circumpolar transport results under Eocene surface forcing. This leads to warm and buoyant coastal water around Antarctica, which may impede the formation of deep waters and convective processes. This suggests that a change in deep water formation might be required to increase the density contrast across the Southern Ocean and increase circumpolar transport. Here we use a simple reduced gravity model with two basins, to represent the Atlantic and the Pacific. This fixes the density difference between surface and deep water and allows us to isolate the impact of deep water formation on circumpolar transport. With no obstacle on the southern boundary the circumpolar current increases its transport from 82.3 to 270.0 Sv with deep water formation. Placing an Antipodean landmass on the southern boundary reduces this transport as the landmass increases in size. However, circumpolar flow north of this landmass remains a possibility even without deep water formation. Weak circumpolar transport continues until the basin is completely blocked by the Antipodes. When the Antipodes is instead allowed to split from the southern boundary, circumpolar transport recovers to its unobstructed value. Flow rapidly switches to south of the Antipodes when the gateway is narrow.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141135907","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}
I. S. Nurhati, M. N. Evans, S. Y. Cahyarini, R. D. D’Arrigo, K. Yoshimura, S. H. S. Herho
The hydroclimatic response of the El Niño‐Southern Oscillation (ENSO) to external radiative forcing remains controversial and difficult to project with confidence for the 21st century. Annually resolved paleoclimatic reconstructions spanning the pre‐ and post‐industrial eras from the Indonesian maritime continent may provide hindcasting and diagnostic targets. Here we report δ18O observations from dendrochronologically dated teak (Tectona grandis L. f.) α‐cellulose samples collected at Muna Island, Sulawesi (5.3°S, 123°E, elevation 10 m), for November‐April growing seasons during the period 1969/70–2004/5. Age‐modeled, annually averaged α‐cellulose δ18O anomalies are significantly correlated with simulated α‐cellulose δ18O at the study site. We show that the correlation is largely explained by the amount effect in local and regional precipitation δ18O. Significant correlation with SST anomalies over the study period suggest that replicated multicentury α‐cellulose records from this archive may be interpreted as ENSO indicators.
{"title":"δ18O of Marine‐Influenced Tectona grandis L. f. From Equatorial Indonesia: A Local Rainfall Amount and Remote ENSO Indicator","authors":"I. S. Nurhati, M. N. Evans, S. Y. Cahyarini, R. D. D’Arrigo, K. Yoshimura, S. H. S. Herho","doi":"10.1029/2023pa004758","DOIUrl":"https://doi.org/10.1029/2023pa004758","url":null,"abstract":"The hydroclimatic response of the El Niño‐Southern Oscillation (ENSO) to external radiative forcing remains controversial and difficult to project with confidence for the 21st century. Annually resolved paleoclimatic reconstructions spanning the pre‐ and post‐industrial eras from the Indonesian maritime continent may provide hindcasting and diagnostic targets. Here we report δ18O observations from dendrochronologically dated teak (Tectona grandis L. f.) α‐cellulose samples collected at Muna Island, Sulawesi (5.3°S, 123°E, elevation 10 m), for November‐April growing seasons during the period 1969/70–2004/5. Age‐modeled, annually averaged α‐cellulose δ18O anomalies are significantly correlated with simulated α‐cellulose δ18O at the study site. We show that the correlation is largely explained by the amount effect in local and regional precipitation δ18O. Significant correlation with SST anomalies over the study period suggest that replicated multicentury α‐cellulose records from this archive may be interpreted as ENSO indicators.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141141417","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}
The upper water‐column dynamics and surface productivity variability in the Northeastern Atlantic Ocean across the Marine Isotope Stage (MIS) 7 interglacial complex is not well understood. Here, we present high‐resolution planktic foraminiferal proxies combined with Artificial Neural Network based‐sea‐surface temperature (SST) and ice‐rafted detritus records from International Ocean Discovery Program Site U1385, SW Iberian Margin for the intervals representing MIS 8 deglaciation, MIS 7 interglacial complex and MIS 6 glacial inception. The long‐term SST pattern is modulated by insolation and precession parameters across the MIS 7 interglacial complex and is superimposed by the millennial‐scale variability (stadials at ∼250, ∼243, ∼230, ∼221, ∼203, ∼196 and ∼192 ka). The regional SST records indicate high temperature gradient (∼6°C) between the sub‐polar North Atlantic Ocean and the SW Iberian Margin during MIS 7d which enhanced the moisture transport from mid‐to‐high latitudes. Further, low obliquity with low insolation induced cooling at high latitudes and promoted the expansion of ice‐sheets during MIS 7d. Comparison of our faunal proxies with the published marine and terrestrial records from SW Europe and western Mediterranean Sea suggested a weakening and southward shift of Azores High (AH) pressure system, similar to the present‐day (−) NAO‐like atmospheric configuration during the early phases of MIS 7e, MIS 7c and MIS 7a, resulting reduced surface productivity of SW Iberian Margin. During the late phases of MIS 7e, MIS 7c and MIS 7a, the AH pressure system strengthened and shifted northward causing the intensification of the trade winds, a scenario similar to present‐day (+) NAO‐like atmospheric configuration, which resulted in high surface productivity of SW Iberian Margin.
人们对东北大西洋整个海洋同位素阶段（MIS）7间冰期的上层水柱动力学和表层生产力变异还不甚了解。在此，我们展示了伊比利亚西南边缘国际大洋发现计划 U1385 站的高分辨率浮游有孔虫代用指标，以及基于人工神经网络的海表温度（SST）和冰植碎屑记录，这些记录代表了 MIS 8 脱冰期、MIS 7 间冰期复合体和 MIS 6 冰期开始的时间段。在整个 MIS 7 间冰期中，长期 SST 模式受日照和前向参数的影响，并与千年尺度的变化（250 ∼、243 ∼、230 ∼、221 ∼、203 ∼、196 ∼ 和 192 ka 时的叠加）相叠加。区域性海温记录表明，在 MIS 7d 期间，亚极地北大西洋与伊比利亚边缘西南部之间的温度梯度较高（∼6°C），增强了中高纬度的水汽输送。此外，低纬度和低日照导致了高纬度地区的降温，促进了MIS 7d期间冰盖的扩张。将我们的动物代用指标与欧洲西南部和地中海西部已发表的海洋和陆地记录进行比较后发现，在 MIS 7e、MIS 7c 和 MIS 7a 早期阶段，亚速尔高压（AH）系统减弱并南移，类似于现在的（-）NAO 大气配置，导致伊比利亚边缘西南部的地表生产力降低。在 MIS 7e、MIS 7c 和 MIS 7a 的晚期，AH 气压系统增强并向北移动，导致信风增强，这种情况类似于现在的（+）NAO 大气配置，从而导致伊比利亚边缘西南部的地表生产力提高。
{"title":"New Insights Into the Surface‐Ocean Dynamics of the Northeastern Atlantic Ocean Across the Marine Isotope Stage 7","authors":"Harshit Singh, Arun Deo Singh","doi":"10.1029/2023pa004722","DOIUrl":"https://doi.org/10.1029/2023pa004722","url":null,"abstract":"The upper water‐column dynamics and surface productivity variability in the Northeastern Atlantic Ocean across the Marine Isotope Stage (MIS) 7 interglacial complex is not well understood. Here, we present high‐resolution planktic foraminiferal proxies combined with Artificial Neural Network based‐sea‐surface temperature (SST) and ice‐rafted detritus records from International Ocean Discovery Program Site U1385, SW Iberian Margin for the intervals representing MIS 8 deglaciation, MIS 7 interglacial complex and MIS 6 glacial inception. The long‐term SST pattern is modulated by insolation and precession parameters across the MIS 7 interglacial complex and is superimposed by the millennial‐scale variability (stadials at ∼250, ∼243, ∼230, ∼221, ∼203, ∼196 and ∼192 ka). The regional SST records indicate high temperature gradient (∼6°C) between the sub‐polar North Atlantic Ocean and the SW Iberian Margin during MIS 7d which enhanced the moisture transport from mid‐to‐high latitudes. Further, low obliquity with low insolation induced cooling at high latitudes and promoted the expansion of ice‐sheets during MIS 7d. Comparison of our faunal proxies with the published marine and terrestrial records from SW Europe and western Mediterranean Sea suggested a weakening and southward shift of Azores High (AH) pressure system, similar to the present‐day (−) NAO‐like atmospheric configuration during the early phases of MIS 7e, MIS 7c and MIS 7a, resulting reduced surface productivity of SW Iberian Margin. During the late phases of MIS 7e, MIS 7c and MIS 7a, the AH pressure system strengthened and shifted northward causing the intensification of the trade winds, a scenario similar to present‐day (+) NAO‐like atmospheric configuration, which resulted in high surface productivity of SW Iberian Margin.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141048964","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}
Kwangkyu Park, Seung‐Il Nam, Christoph M. Vogt, T. Frederichs, Jung‐Hyun Kim, B. Khim
We present the glacial history of the Makarov Basin (western Arctic Ocean) during the last ∼1.1 Myr, with sediment provenances using the newly refined chronostratigraphy of core ARA03B‐41GC02. According to the principal component analysis of the bulk mineral assemblages, felsic minerals were dominant, and their ratios (K‐feldspar/plagioclase and quartz/feldspars) indicated that sediment supply to the Makarov Basin was mainly from the Siberian margin and partly from northern North America, including the Canadian Arctic. However, their occurrence did not vary significantly between interglacials and glacials due to the mixed sources. In contrast, clinopyroxene and dolomite indicated specific sediment origins from the eastern Siberian margin and northern North America, respectively. The clinopyroxene content followed an eccentricity cycle (∼100‐Kyr) during the early to middle Pleistocene, suggesting that the eustatic sea level changes may have influenced its input from the eastern Siberian margin. The dolomite, transported primarily by icebergs from the Arctic sector of the Laurentide Ice Sheet (LIS) in northern North America, has also followed the same cycle since the early Pleistocene. Thus, the mineralogical signals highlight that sediment origins and transport processes in the Makarov Basin were related to ice sheet evolution at the eccentricity cycle. In addition, dolomite deposition in the Makarov Basin began by the early Pleistocene (∼790 ka), ∼150 ka earlier than in previous North Atlantic records (∼640 ka), indicating the earlier LIS calving in the Arctic sector than in the Atlantic sector.
{"title":"Cryospheric and Oceanographic Evolution in the Arctic Makarov Basin Since the Early Pleistocene Revealed by Bulk Mineral Assemblages","authors":"Kwangkyu Park, Seung‐Il Nam, Christoph M. Vogt, T. Frederichs, Jung‐Hyun Kim, B. Khim","doi":"10.1029/2023pa004747","DOIUrl":"https://doi.org/10.1029/2023pa004747","url":null,"abstract":"We present the glacial history of the Makarov Basin (western Arctic Ocean) during the last ∼1.1 Myr, with sediment provenances using the newly refined chronostratigraphy of core ARA03B‐41GC02. According to the principal component analysis of the bulk mineral assemblages, felsic minerals were dominant, and their ratios (K‐feldspar/plagioclase and quartz/feldspars) indicated that sediment supply to the Makarov Basin was mainly from the Siberian margin and partly from northern North America, including the Canadian Arctic. However, their occurrence did not vary significantly between interglacials and glacials due to the mixed sources. In contrast, clinopyroxene and dolomite indicated specific sediment origins from the eastern Siberian margin and northern North America, respectively. The clinopyroxene content followed an eccentricity cycle (∼100‐Kyr) during the early to middle Pleistocene, suggesting that the eustatic sea level changes may have influenced its input from the eastern Siberian margin. The dolomite, transported primarily by icebergs from the Arctic sector of the Laurentide Ice Sheet (LIS) in northern North America, has also followed the same cycle since the early Pleistocene. Thus, the mineralogical signals highlight that sediment origins and transport processes in the Makarov Basin were related to ice sheet evolution at the eccentricity cycle. In addition, dolomite deposition in the Makarov Basin began by the early Pleistocene (∼790 ka), ∼150 ka earlier than in previous North Atlantic records (∼640 ka), indicating the earlier LIS calving in the Arctic sector than in the Atlantic sector.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141052251","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}
Tingli Yan, Kefu Yu, Leilei Jiang, Yueer Li, N. Zhao
Understanding the history of sea‐level changes in the past and the associated mechanisms is crucial for predicting sea level in the future. The South China Sea is the largest semi‐enclosed marginal sea in the western tropical Pacific. Previous studies showed that this region experienced several sea‐level fluctuations up to half a meter on centennial timescales ∼7,000 cal yr BP. These fluctuations were greater in magnitude than the rise in global mean sea level induced by greenhouse effect over the 20th century. However, whether such sea‐level fluctuations occurred in a wider temporal context and their potential causes remain unclear. To answer these questions, we reconstructed the mid‐Holocene sea‐level fluctuations in the northern South China Sea using nine coral microatoll fossils collected from Hainan Island. The results suggest that sea‐level fluctuations with amplitude of about half a meter on centennial timescales were common during 6,143–4,384 cal yr BP. Based on recent studies of sea‐level driving mechanisms in the South China Sea and paleoclimate reconstructions, we infer that these sea‐level fluctuations were likely driven by changes of Walker circulation intensity. Due to the internal variability of the climate system, the possibility of similar sea‐level fluctuations in the foreseeable future cannot be ruled out.
了解过去海平面变化的历史和相关机制对于预测未来海平面至关重要。南海是西太平洋热带地区最大的半封闭边缘海。之前的研究表明，该区域经历了数次海平面波动，波动幅度在百年时间尺度上可达半米，即 7,000 cal yr BP。这些波动的幅度大于 20 世纪温室效应引起的全球平均海平面的上升。然而，这种海平面波动是否发生在更广阔的时间范围内及其潜在原因仍不清楚。为了回答这些问题，我们利用从海南岛采集的九个珊瑚微领化石重建了中国南海北部全新世中期的海平面波动。结果表明，在公元前6,143-4,384年期间，海平面波动幅度约为半米，时间尺度为百年。根据最近对南海海平面驱动机制的研究和古气候重建，我们推断这些海平面波动可能是由沃克环流强度变化驱动的。由于气候系统的内部变异性，不排除在可预见的未来出现类似海平面波动的可能性。
{"title":"Significant Sea‐Level Fluctuations in the Western Tropical Pacific During the Mid‐Holocene","authors":"Tingli Yan, Kefu Yu, Leilei Jiang, Yueer Li, N. Zhao","doi":"10.1029/2023pa004783","DOIUrl":"https://doi.org/10.1029/2023pa004783","url":null,"abstract":"Understanding the history of sea‐level changes in the past and the associated mechanisms is crucial for predicting sea level in the future. The South China Sea is the largest semi‐enclosed marginal sea in the western tropical Pacific. Previous studies showed that this region experienced several sea‐level fluctuations up to half a meter on centennial timescales ∼7,000 cal yr BP. These fluctuations were greater in magnitude than the rise in global mean sea level induced by greenhouse effect over the 20th century. However, whether such sea‐level fluctuations occurred in a wider temporal context and their potential causes remain unclear. To answer these questions, we reconstructed the mid‐Holocene sea‐level fluctuations in the northern South China Sea using nine coral microatoll fossils collected from Hainan Island. The results suggest that sea‐level fluctuations with amplitude of about half a meter on centennial timescales were common during 6,143–4,384 cal yr BP. Based on recent studies of sea‐level driving mechanisms in the South China Sea and paleoclimate reconstructions, we infer that these sea‐level fluctuations were likely driven by changes of Walker circulation intensity. Due to the internal variability of the climate system, the possibility of similar sea‐level fluctuations in the foreseeable future cannot be ruled out.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141031211","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}
M. Hollstein, Markus Kienast, A. Lückge, Yusuke Yokoyama, M. Mohtadi
Sea surface temperature (SST) across the Coral Sea is tightly coupled to the regional and larger‐scale ocean circulation and climate. Continuous records that reflect past changes in Coral Sea SST in high resolution are missing, however. Here, we present Mg/Ca‐ and alkenone‐based SST reconstructions from the northwestern Coral Sea that cover the past 130 kyr. Our SST estimates vary in line with southern hemisphere high latitude climate variability, linked to atmospheric CO2. Combining the newly generated with published records, we find that the SST changes across the Coral Sea show a large spatial heterogeneity during the last glacial‐interglacial cycle. Particularly prior to 60 ka, precession exerts a discernible influence on the meridional SST gradients across the Coral Sea, as well as between the Coral Sea and southern Western Pacific Warm Pool. We posit that these changes are linked to the regional trade winds and the South Pacific subtropical gyre circulation, and/or to changes in the El Niño Southern Oscillation.
珊瑚海的海面温度（SST）与区域和更大尺度的海洋环流和气候密切相关。然而，高分辨率地反映珊瑚海海面温度过去变化的连续记录并不存在。在此，我们展示了珊瑚海西北部过去 130 千年基于镁/碳-钙和烯酮的海温重建结果。我们的海温估计值与南半球高纬度气候变异性一致，与大气中的二氧化碳有关。结合新生成的记录和已发表的记录，我们发现在上一个冰川-间冰期周期中，整个珊瑚海的海温变化呈现出很大的空间异质性。特别是在 60 ka 以前，前向运动对整个珊瑚海以及珊瑚海与西太平洋暖池南部之间的经向 SST 梯度产生了明显的影响。我们认为这些变化与区域信风和南太平洋副热带涡旋环流和/或厄尔尼诺南方涛动的变化有关。
{"title":"Sea Surface Temperatures Across the Coral Sea Over the Last Glacial‐Interglacial Cycle","authors":"M. Hollstein, Markus Kienast, A. Lückge, Yusuke Yokoyama, M. Mohtadi","doi":"10.1029/2023pa004757","DOIUrl":"https://doi.org/10.1029/2023pa004757","url":null,"abstract":"Sea surface temperature (SST) across the Coral Sea is tightly coupled to the regional and larger‐scale ocean circulation and climate. Continuous records that reflect past changes in Coral Sea SST in high resolution are missing, however. Here, we present Mg/Ca‐ and alkenone‐based SST reconstructions from the northwestern Coral Sea that cover the past 130 kyr. Our SST estimates vary in line with southern hemisphere high latitude climate variability, linked to atmospheric CO2. Combining the newly generated with published records, we find that the SST changes across the Coral Sea show a large spatial heterogeneity during the last glacial‐interglacial cycle. Particularly prior to 60 ka, precession exerts a discernible influence on the meridional SST gradients across the Coral Sea, as well as between the Coral Sea and southern Western Pacific Warm Pool. We posit that these changes are linked to the regional trade winds and the South Pacific subtropical gyre circulation, and/or to changes in the El Niño Southern Oscillation.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141035296","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}
S. Katz, Naomi E. Levin, M. B. Abbott, D. Rodbell, B. Passey, Nicole M. DeLuca, D. Larsen, A. Woods
Global climate during the Holocene was relatively stable compared to the late Pleistocene. However, evidence from lacustrine records in South America suggests that tropical latitudes experienced significant water balance variability during the Holocene, rather than quiescence. For example, a tight coupling between insolation and carbonate δ18O records from central Andean lakes (e.g., Lakes Junín, Pumacocha) suggest water balance is tied directly to South American summer monsoon (SASM) strength. However, lake carbonate δ18O records also incorporate information about temperature and evaporation. To overcome this ambiguity, clumped and triple oxygen isotope records can provide independent constraints on temperature and evaporation. Here, we use clumped and triple oxygen isotopes to develop Holocene temperature and evaporation records from three central Andean lakes, Lakes Junín, Pumacocha, and Mehcocha, to build a more complete picture of regional water balance (P–E). We find that Holocene water temperatures at all three lakes were stable and slightly warmer than during the latest Pleistocene. These results are consistent with global data assimilations and records from the foothills and Amazon basin. In contrast, evaporation was highly variable and tracks SASM intensity. The hydrologic response of each lake to SASM depends greatly on the physical characteristics of the lake basin, but they all record peak evaporation in the early to mid‐Holocene (11,700 to 4,200 years BP) when regional insolation was relatively low and the SASM was weak. These results corroborate other central Andean records and suggest synchronous, widespread water stress tracks insolation‐paced variability in SASM strength.
{"title":"Holocene Temperature and Water Stress in the Peruvian Andes: Insights From Lake Carbonate Clumped and Triple Oxygen Isotopes","authors":"S. Katz, Naomi E. Levin, M. B. Abbott, D. Rodbell, B. Passey, Nicole M. DeLuca, D. Larsen, A. Woods","doi":"10.1029/2023pa004827","DOIUrl":"https://doi.org/10.1029/2023pa004827","url":null,"abstract":"Global climate during the Holocene was relatively stable compared to the late Pleistocene. However, evidence from lacustrine records in South America suggests that tropical latitudes experienced significant water balance variability during the Holocene, rather than quiescence. For example, a tight coupling between insolation and carbonate δ18O records from central Andean lakes (e.g., Lakes Junín, Pumacocha) suggest water balance is tied directly to South American summer monsoon (SASM) strength. However, lake carbonate δ18O records also incorporate information about temperature and evaporation. To overcome this ambiguity, clumped and triple oxygen isotope records can provide independent constraints on temperature and evaporation. Here, we use clumped and triple oxygen isotopes to develop Holocene temperature and evaporation records from three central Andean lakes, Lakes Junín, Pumacocha, and Mehcocha, to build a more complete picture of regional water balance (P–E). We find that Holocene water temperatures at all three lakes were stable and slightly warmer than during the latest Pleistocene. These results are consistent with global data assimilations and records from the foothills and Amazon basin. In contrast, evaporation was highly variable and tracks SASM intensity. The hydrologic response of each lake to SASM depends greatly on the physical characteristics of the lake basin, but they all record peak evaporation in the early to mid‐Holocene (11,700 to 4,200 years BP) when regional insolation was relatively low and the SASM was weak. These results corroborate other central Andean records and suggest synchronous, widespread water stress tracks insolation‐paced variability in SASM strength.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141144950","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}
Bianca R. Spiering, E. Wubben, Frederik J. Hilgen, A. Sluijs
Detailed analysis of tropical climate dynamics is lacking for the Early to Middle Miocene, even though this time interval bears important analogies for future climates. Based on high‐resolution proxy reconstructions of sea surface temperature, export productivity and dust supply at Ocean Drilling Program Site 959, we investigate astronomical forcing of the West African monsoon in the eastern equatorial Atlantic across the prelude, onset, and continuation of the Miocene Climatic Optimum (MCO; 18–15 Ma). Along with previously identified eccentricity periodicities of ∼400 and ∼100 kyr, our records show that climate varied on ∼27–17 kyr, ∼41 kyr, and ∼60–50 kyr timescales, which we attribute to precession, obliquity, and their combination tones, respectively. The relative contribution of these astronomical cycles differed between proxies and through time. Three intervals with distinct variability were recognized, which are particularly clear in the temperature record: (a) strong eccentricity, obliquity, and precession variability prior to the MCO (18.2–17.7 Ma), (b) strong influence of obliquity just after the onset of the MCO (16.9–16.3 Ma) concurring with a 2.4 Myr eccentricity minimum, and (c) dominant eccentricity and precession variability during the MCO between 16.3 and 15.0 Ma. Sedimentation at Site 959 was influenced by astronomically paced variations in upwelling intensity and North African aridity related to West African monsoon dynamics. Continuously present patterns of precession imply low‐latitude forcing, while asymmetric eccentricity and obliquity imprints and strong obliquity influence suggest that Site 959 was also affected by high‐latitude, glacial‐interglacial dynamics.
{"title":"Early to Middle Miocene Astronomically Paced Climate Dynamics in the Eastern Equatorial Atlantic","authors":"Bianca R. Spiering, E. Wubben, Frederik J. Hilgen, A. Sluijs","doi":"10.1029/2023pa004768","DOIUrl":"https://doi.org/10.1029/2023pa004768","url":null,"abstract":"Detailed analysis of tropical climate dynamics is lacking for the Early to Middle Miocene, even though this time interval bears important analogies for future climates. Based on high‐resolution proxy reconstructions of sea surface temperature, export productivity and dust supply at Ocean Drilling Program Site 959, we investigate astronomical forcing of the West African monsoon in the eastern equatorial Atlantic across the prelude, onset, and continuation of the Miocene Climatic Optimum (MCO; 18–15 Ma). Along with previously identified eccentricity periodicities of ∼400 and ∼100 kyr, our records show that climate varied on ∼27–17 kyr, ∼41 kyr, and ∼60–50 kyr timescales, which we attribute to precession, obliquity, and their combination tones, respectively. The relative contribution of these astronomical cycles differed between proxies and through time. Three intervals with distinct variability were recognized, which are particularly clear in the temperature record: (a) strong eccentricity, obliquity, and precession variability prior to the MCO (18.2–17.7 Ma), (b) strong influence of obliquity just after the onset of the MCO (16.9–16.3 Ma) concurring with a 2.4 Myr eccentricity minimum, and (c) dominant eccentricity and precession variability during the MCO between 16.3 and 15.0 Ma. Sedimentation at Site 959 was influenced by astronomically paced variations in upwelling intensity and North African aridity related to West African monsoon dynamics. Continuously present patterns of precession imply low‐latitude forcing, while asymmetric eccentricity and obliquity imprints and strong obliquity influence suggest that Site 959 was also affected by high‐latitude, glacial‐interglacial dynamics.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141029009","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}
B. Niederbockstruck, H. L. Jones, K. Yasukawa, I. Raffi, E. Tanaka, T. Westerhold, M. Ikehara, U. Röhl
The late Paleocene to early Eocene interval is characterized by a series of carbon perturbations that caused transient warming (hyperthermal) events, of which the Paleocene‐Eocene Thermal Maximum (PETM) was the largest. These hyperthermals can be recognized in the pelagic sedimentary record as paired negative δ13C and δ18O excursions, in addition to decreased calcium carbonate and increased iron content caused by carbonate dissolution. However, current data are predominantly sourced from the equatorial‐to subequatorial regions. Here we present a new high‐latitude late Paleocene—early Eocene record, recovered during International Ocean Discovery Program (IODP) Expedition 378 on the Campbell Plateau off New Zealand, in the southwest Pacific Ocean. To construct an age model, we correlated our chemostratigraphic and biostratigraphic data to existing astronomically‐tuned age models from Walvis Ridge (South Atlantic Ocean) and Demerara Rise (equatorial Atlantic Ocean). Our results indicate that the Site U1553 composite section spans ∼7 million years of the latest Paleocene to early Eocene (50.5–57.5 Ma), and preserves many of the early Eocene hyperthermals; including a PETM interval that is more expanded than elsewhere in this region. However, construction of the age model also revealed discrepancies between the chemostratigraphic and biostratigraphic tie points used for correlation. This is likely due to latitudinal diachroneity in the calcareous nannofossil biostratigraphic datums, which are primarily based on low‐to mid‐latitude assemblages. Therefore, our study highlights the need to establish a revised calcareous nannofossil biozonation that is more appropriate for high‐latitude age models.
{"title":"Apparent Diachroneity of Calcareous Nannofossil Datums During the Early Eocene in the High‐Latitude South Pacific Ocean","authors":"B. Niederbockstruck, H. L. Jones, K. Yasukawa, I. Raffi, E. Tanaka, T. Westerhold, M. Ikehara, U. Röhl","doi":"10.1029/2023pa004801","DOIUrl":"https://doi.org/10.1029/2023pa004801","url":null,"abstract":"The late Paleocene to early Eocene interval is characterized by a series of carbon perturbations that caused transient warming (hyperthermal) events, of which the Paleocene‐Eocene Thermal Maximum (PETM) was the largest. These hyperthermals can be recognized in the pelagic sedimentary record as paired negative δ13C and δ18O excursions, in addition to decreased calcium carbonate and increased iron content caused by carbonate dissolution. However, current data are predominantly sourced from the equatorial‐to subequatorial regions. Here we present a new high‐latitude late Paleocene—early Eocene record, recovered during International Ocean Discovery Program (IODP) Expedition 378 on the Campbell Plateau off New Zealand, in the southwest Pacific Ocean. To construct an age model, we correlated our chemostratigraphic and biostratigraphic data to existing astronomically‐tuned age models from Walvis Ridge (South Atlantic Ocean) and Demerara Rise (equatorial Atlantic Ocean). Our results indicate that the Site U1553 composite section spans ∼7 million years of the latest Paleocene to early Eocene (50.5–57.5 Ma), and preserves many of the early Eocene hyperthermals; including a PETM interval that is more expanded than elsewhere in this region. However, construction of the age model also revealed discrepancies between the chemostratigraphic and biostratigraphic tie points used for correlation. This is likely due to latitudinal diachroneity in the calcareous nannofossil biostratigraphic datums, which are primarily based on low‐to mid‐latitude assemblages. Therefore, our study highlights the need to establish a revised calcareous nannofossil biozonation that is more appropriate for high‐latitude age models.","PeriodicalId":54239,"journal":{"name":"Paleoceanography and Paleoclimatology","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140784433","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}
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