Global and Planetary Change最新文献_第6页

Magnetic evidence of redox transition event in the Okinawa Trough during the early-middle Holocene and its links to the Kuroshio Current evolution 全新世早中期冲绳海槽氧化还原转变事件的磁学证据及其与黑潮演化的联系

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2025.104699

Feng Wang , Tuqin Huang , Zhongbo Wang , Weiguo Zhang , Pengyu Qiao , Haiyan Tang , Xi Mei , Ping Yin , Zhongping Lai

The Kuroshio Current significantly influences the physical, chemical, and biological properties in the western Pacific Ocean, while its strength and path in the Okinawa Trough during the Holocene remains unclear. Previous studies have not established consistent conclusions due to the multiple explanations for sediment provenance proxies, but these inconsistencies can potentially be addressed by identifying redox variability through diagenetic effects on magnetic minerals. Magnetic data (χ, SIRM, χ_ARM, and S-ratios) obtained from cores SHDZ10 and A4 in the middle Okinawa Trough indicate an intensified reductive diagenesis effect prior to the early-middle Holocene period, whereas a contrasting trend is observed since the early-middle Holocene. Geochemical analyses (Mo, Mn, Mo/Mn, Mn/Al, TOC and TS) and Pulleniatina obliquiloculata content variations suggest that the decrease in early diagenesis since early-middle Holocene was a consequence of increased oxygenation, which is related to a strengthened Kuroshio Current and enhanced deep-water ventilation. By synthesizing the observed redox transition phenomena in nearby sediment cores (MD012403, MD012404, KX12–3, MD063–05, CSH1), we discover a coherent redox transition event during the early-middle Holocene. The occurrence ages show millennial-scale variability from south to north, which may suggest a periodic northward movement trajectory of a strengthened Kuroshio Current. This study not only provides novel insights into the reconstruction of the Kuroshio Current evolution, but also highlights the applicability of environmental magnetism methods in investigating deep-water ventilation.

黑潮对西太平洋的物理、化学和生物特性有显著影响，但其在全新世冲绳海槽的强度和路径尚不清楚。由于对沉积物物源的多种解释，以往的研究尚未得出一致的结论，但这些不一致性可以通过对磁性矿物的成岩作用确定氧化还原变异性来解决。冲绳海槽中部SHDZ10和A4岩心的磁性资料（χ、SIRM、χ arm和s比）表明，早中全新世之前还原成岩作用增强，而早中全新世以来则呈现相反的趋势。地球化学分析（Mo、Mn、Mo/Mn、Mn/Al、TOC和TS）和斜叶扁豆（Pulleniatina obliquilocata）含量变化表明，全新世早中期以来早期成岩作用减少是氧化作用增强的结果，这与黑潮增强和深水通风增强有关。综合观测到的MD012403、MD012404、KX12-3、MD063-05、CSH1等沉积物岩心的氧化还原转变现象，发现了全新世早中期前后的连续氧化还原转变事件。从南向北呈现出千禧年尺度的变化，这可能表明黑潮的周期性北移轨迹。该研究不仅为重建黑潮演化提供了新的见解，而且突出了环境磁学方法在研究深水通风中的适用性。

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引用次数: 0

Regulation and response of heterotrophic bacterial production to environmental changes in marginal seas of the Western Pacific Ocean 西太平洋边缘海域异养细菌生产对环境变化的调控和响应

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104678

Qiao Liu , Jinyan Wang , Xiao-Jun Li , Ni Meng , Gui-Peng Yang , Guiling Zhang , Guang-Chao Zhuang

Heterotrophic bacterial production represents an important part of microbial food web processes in marine ecosystems and plays a significant role in biogeochemical carbon cycle. As environmental factors have changed in marginal seas of the Western Pacific Ocean over the past 20 years, the response and regulation of bacterial production remain poorly understood. In this study, we quantified bacterial production rates using the ³H-leucine incorporation method and investigated the factors influencing bacterial production distributions in the East China Sea and the Yellow Sea. Our data revealed that bacterial production varied largely (1.6–24.4 mg C m⁻³ d⁻¹) in the surface waters, and higher rates were observed at temperate sites in the East China Sea. Incubation experiments under different temperature or nutrient conditions demonstrated that elevated temperature or the addition of silicate, DIN and phosphate could simulate heterotrophic activity. The decadal increases of BP could be a result of microbial response to the variations in temperature, nutrient levels, and dissolved oxygen that are closely linked to food-web dynamics and biogeochemical processes. High ratios of integrated bacterial production to primary production suggested bacterial production could be supported by non-phytoplanktonic carbon sources, while the low bacterial growth efficiency indicated that a large fraction of carbon was respired in the offshore waters. These results provided insights into the regulations of BP and heterotrophic response to environmental evolution in marginal seas of the Western Pacific Ocean.

异养细菌的产生是海洋生态系统微生物食物网过程的重要组成部分，在生物地球化学碳循环中起着重要作用。近20年来，随着西太平洋边缘海域环境因素的变化，对细菌产生的反应和调控仍知之甚少。本研究采用3h -亮氨酸掺入法定量研究了东海和黄海海域细菌产量分布的影响因素。我们的数据显示，细菌产量在地表水中变化很大（1.6-24.4 mg C m−3 d−1），并且在东海温带地区观察到更高的速率。不同温度和营养条件下的培养实验表明，提高温度或添加硅酸盐、DIN和磷酸盐可以模拟异养活性。BP的年代际增加可能是微生物对温度、营养水平和溶解氧变化的反应，这些变化与食物网动态和生物地球化学过程密切相关。综合细菌生产与初级生产的高比率表明细菌生产可能由非浮游植物碳源支持，而细菌生长效率低表明大部分碳是在近海水域呼吸的。这些结果为揭示西太平洋边缘海BP的变化规律和异养响应环境演化提供了新的思路。

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引用次数: 0

Late Miocene-early Pliocene hydroclimate evolution of the western Altiplano, northern Chile: Implications for aridification trends under warming climate conditions 智利北部Altiplano西部中新世晚期-上新世早期水文气候演化：气候变暖条件下干旱化趋势的影响

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104674

Carlie Mentzer , Carmala Garzione , Carlos Jaramillo , Luis Felipe Hinojosa , Jaime Escobar , Nataly Glade , Sebastian Gomez , Deepshikha Upadhyay , Aradhna Tripati , Kaustubh Thirumalai

The Miocene-Pliocene boundary (∼5.3 million years ago, Ma) represents a climate transition, where global warming resulted in a rise in sea surface temperatures from near modern values in the late Miocene, to sustained, warmer than modern values in the early Pliocene. Estimated atmospheric CO₂ concentrations were within the range of anthropogenic values. Thus, this transition provides an opportunity to evaluate hydroclimate responses to warming, when the Earth system was in equilibrium with near modern atmospheric CO₂ levels. Here, we utilize lacustrine carbonate stable and clumped isotope methods, and palynology, to investigate hydroclimate trends within the western Altiplano of Chile during the late Miocene and early Pliocene. The results provide observational support for a warmer and wetter-than-modern climate over these timeframes. However, increasing aridity across the Miocene-Pliocene boundary suggests a hydroclimate response to global climate forcing. Given the sensitivity of the region's climate to disturbances in tropical Pacific, ocean-atmospheric processes, we speculate that this aridification may reflect progressive weakening of the Pacific Walker Circulation, in response to global warming.

中新世-上新世边界（距今 530 万年前，Ma）是一个气候转变期，全球变暖导致海面温度从中新世晚期的接近现代温度值上升到上新世早期的持续、比现代温度值更高的温度值。估计的大气二氧化碳浓度在人为值范围之内。因此，当地球系统与接近现代的大气二氧化碳水平处于平衡状态时，这一转变为评估水文气候对变暖的反应提供了机会。在这里，我们利用湖泊碳酸盐稳定同位素和团块同位素方法以及古植物学，研究了智利西部阿尔蒂普拉诺在中新世晚期和上新世早期的水文气候趋势。研究结果为这些时期的气候比现代气候温暖湿润提供了观测支持。然而，中新世-上新世边界日益干旱的现象表明，水文气候对全球气候胁迫做出了反应。考虑到该地区气候对热带太平洋海洋-大气过程干扰的敏感性，我们推测这种干旱化可能反映了太平洋沃克环流因全球变暖而逐渐减弱。

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引用次数: 0

From holocene to anthropogenic impact: Surpassing coral's pH up-regulation capacity under ocean acidification 从全新世到人为影响：在海洋酸化下超越珊瑚的pH上调能力

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104683

Huiling Kang , Xuefei Chen , Guangchao Deng , Jian-xin Zhao , Gangjian Wei

Corals' regulation of internal calcifying fluid (CF or cf) chemistry is crucial for their extraordinary calcification capacity, endowing them with a certain ability to cope with environmental changes such as anthropogenic ocean acidification (OA) and warming. However, it remains unclear whether the impacts of these changes on corals have substantially surpassed their regulation capacity, particularly in comparison to the CF chemistry responses to natural climate variability with minor or no human perturbation. In this study, we reconstructed the pH, dissolved inorganic carbon, and carbonate ion concentrations in coral CF (pH_cf, DIC_cf, and [CO₃²⁻]_cf) during the Mid- to Late-Holocene, by analyzing the skeletal δ¹¹B and B/Ca of 80 Porites spp. from eastern Hainan Island in the South China Sea (SCS). Our records indicate considerable inter-colony variations in CF chemistry, with maximum disparities reaching 0.18 units for pH_cf and 1664 μmol/kg for DIC_cf. With this in mind, we found no clear responses of coral DIC_cf to the climate fluctuations during the past ∼5500 years, nor evident differences in pH_cf and [CO₃²⁻]_cf across pre-industrial natural epochs. However, pH_cf and [CO₃²⁻]_cf of modern corals have significantly declined compared to fossil corals. Further analyzes compiling global data on Porites spp. also confirm this pronounced pH_cf decrease in modern corals, suggesting the limitations of pantropical corals to counteract OA by up-regulating pH_cf. Importantly, these fossil and modern corals reveal a clear long-term pH_cf descending trend parallel to atmospheric CO₂ changes, supporting the reliability of coral δ¹¹B in recording long-term changes in seawater pH (pH_sw).

珊瑚对内部钙化液（CF或CF）化学的调节对其非凡的钙化能力至关重要，使其具有一定的应对人为海洋酸化（OA）和变暖等环境变化的能力。然而，目前尚不清楚这些变化对珊瑚的影响是否大大超过了它们的调节能力，特别是与很少或没有人为扰动的CF化学对自然气候变化的反应相比。本文通过对南海海南岛东部80个Porites sp .的骨骼δ11B和B/Ca的分析，重建了中-晚全新世珊瑚CF （pHcf、DICcf和[CO32−]CF）的pH、溶解无机碳和碳酸盐离子浓度。我们的记录表明，菌落间的CF化学差异很大，pHcf的最大差异为0.18 μmol/kg， DICcf的最大差异为1664 μmol/kg。考虑到这一点，我们发现珊瑚DICcf在过去~ 5500年间对气候波动没有明确的响应，pHcf和[CO32−]cf在工业化前自然时期也没有明显的差异。然而，与化石珊瑚相比，现代珊瑚的pHcf和[CO32−]cf明显下降。进一步分析汇编的Porites spp.的全球数据也证实了现代珊瑚pHcf的显著下降，这表明泛热带珊瑚通过上调pHcf来抵消OA的局限性。重要的是，这些化石和现代珊瑚揭示了与大气CO2变化平行的pHcf长期下降趋势，支持了珊瑚δ11B记录海水pH （pHsw）长期变化的可靠性。

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引用次数: 0

Marine productivity controlled by oceanic circulation in the Northwest Pacific over the last glacial cycle 最后一次冰期旋回期间西北太平洋海洋环流控制的海洋生产力

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104686

Limin Hu , Hao Fang , Xuefa Shi , Yuying Zhang , Zhifei Duan , Chao Li , Jörg Lippold , Minoru Ikehara , Yiming Luo

The oceanic carbon cycles have a significant effect on the climate transitions by influencing the atmospheric CO₂ levels. As one of the largest carbon sinks, the Northwest Pacific is the key to understand how the carbon cycles react to past and future climate changes. In this study, the marine productivity in Northwest Pacific over the last 25,000 years has been comprehensively reconstructed using ²³⁰Th-normalized biogenic fluxes recorded in a series of sedimentary cores. Our results show contrasting onsets of productivity pulse between cores from the subarctic and the subtropical gyres, while both have been controlled by the nutrient supply related to ocean circulation. Specifically, the wind-driven southward shift of subarctic gyre combined with stronger East Asia winter monsoon during the Last Glacial Maximum and early deglaciation supplied more nutrients to the south and stimulated the subtropical productivity, while this process synchronously limited the subarctic productivity especially with downward extension of the North Pacific Intermediate Water (NPIW). The contraction of subarctic gyre associated with the collapse of the NPIW during the Bølling-Allerød generated the productivity pulse in subarctic region and lowered the subtropical productivity. Terrigenous inputs, reconstructed from ²³²Th fluxes, however, mainly affected the productivity in the subtropical gyre over the last glacial cycle, especially for the marginal region, in contrast to the pelagic subarctic gyre. Our findings reveal an interplay between subarctic and subtropical gyres and their integrated impacts on marine productivity, providing a paleoceanographic perspective to understand the carbon budget across different timescales in the Northwest Pacific.

海洋碳循环通过影响大气CO2水平对气候变化具有重要影响。作为最大的碳汇之一，西北太平洋是了解碳循环如何对过去和未来气候变化作出反应的关键。本文利用一系列沉积岩心记录的230度标准化生物源通量，对西北太平洋近25000年来的海洋生产力进行了全面重建。研究结果表明，亚北极和副热带环流核心区的生产力脉动出现了明显的差异，但两者都受到与海洋环流有关的养分供应的控制。具体而言，末次盛冰期和消冰期早期，亚北极环流的南移与东亚冬季风的增强相结合，为南方提供了更多的营养物质，促进了亚热带生产力的增长，但这一过程同时限制了亚北极生产力，特别是北太平洋中间水（NPIW）的向下延伸。在b ølling- allerd期间，亚北极环流的收缩和NPIW的崩溃产生了亚北极地区的生产力脉冲，降低了副热带生产力。然而，根据232Th通量重建的陆源输入主要影响了末次冰旋回期间副热带环流的生产力，特别是边缘区域的生产力，与远洋亚北极环流形成对比。我们的研究结果揭示了亚北极和亚热带环流之间的相互作用及其对海洋生产力的综合影响，为了解西北太平洋不同时间尺度的碳收支提供了古海洋学视角。

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引用次数: 0

About 868 cal. yr BP tsunami event at the northern South China Sea revealed from offshore sediments 南海北部近海沉积物揭示了约868 cal. yr BP海啸事件

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104685

Yuming Wang , Xiaohong Chen , Adam D. Switzer , Linlin Li , Yang Xu , Yukun Wang , Elaine Tan , Peizhen Zhang

The northern coast of the South China Sea (SCS) is a densely populated and economically important area. Despite the absence of any tsunamigenic events in the last century in this region, their occurrence on a much longer timescale remains largely unknown. Given the catastrophic consequences a potential tsunami event could bring, we aim to bridge this research gap by conducting high-resolution sedimentological, geochemical, and geochronological analyses on two well-preserved offshore sedimentary columns, B01 and D02, from the northern SCS, at depths of −27 and − 46 m, respectively. Using statistical methods, we identified two anomalous sediment units, each ∼30 to 40 cm thick, in both columns. These units are dominated by coarse-grained, poorly sorted sediments with a normally graded sequence. Each unit is rich in biogenic debris, devoid of parallel or cross-bedding, and has a unique set of elemental and isotopic signatures. They contain allochthonous biological species and record a disordered age-depth pattern. Such observations are indicative of the sudden input of marine components, suggesting an instantaneous high-energy event. The median calibrated ages, measured by accelerator mass spectrometry (AMS), from shell and foraminifera in the anomalous units, return the mixed ages of 4454–842 cal. yr BP and 2098–840 cal. yr BP, respectively. Shell and foraminifera above and below the anomalous units define AMS ¹⁴C ages of 951–779 cal. yr BP, with a median age of ∼868 cal. yr BP. Our data collectively point to a tsunami event at ∼868 cal. yr BP, equivalent to the North-Song Dynasty of ∼1000 years ago. This age pattern is consistent with reported tsunami events in and around the SCS, also compatible with historical accounts describing a “tidal overflow in Eastern Guangdong and Eastern Fujian at AD1067–1068” in Chinese documents. Combined with available data, the ca 868 cal. yr BP tsunami event in the SCS likely originated from the joint interaction of earthquakes induced by the Manila Subduction Zone and the Littoral Fault Zone, along with related landslide activities within the northern SCS.

南中国海（SCS）北岸是一个人口稠密、经济重要的地区。尽管该地区在上个世纪没有发生过任何海啸事件，但在更长的时间尺度上发生海啸的情况在很大程度上仍然是未知的。鉴于潜在海啸事件可能带来的灾难性后果，我们对南中国海北部水深分别为-27 米和-46 米的两个保存完好的近海沉积柱 B01 和 D02 进行了高分辨率沉积学、地球化学和地质年代分析，旨在弥补这一研究空白。利用统计方法，我们在这两个沉积柱中发现了两个异常沉积单元，每个单元的厚度在 30 至 40 厘米之间。这些单元以粗粒、分选差的沉积物为主，序列分级正常。每个单元都富含生物碎屑，没有平行或交叉层理，具有独特的元素和同位素特征。它们含有同生生物物种，并记录了无序的年龄-深度模式。这些观察结果表明海洋成分的突然输入，表明这是一个瞬时高能事件。通过加速器质谱法（AMS）测量异常单元中贝壳和有孔虫的校准年龄中值，得出的混合年龄分别为公元前 4454-842 年和公元前 2098-840 年。异常单元上下的贝壳和有孔虫确定的 AMS 14C 年龄为 951-779 大元前，中位年龄为 868 大元前。我们的数据共同表明，海啸发生在公元前 868 年，相当于距今 1000 年的北宋时期。这一年代模式与所报道的南中国海及其周边地区的海啸事件相吻合，也与中国文献中描述的 "公元1067-1068年粤东、闽东潮溢 "的历史记载相吻合。结合现有数据，约公元前 868 年发生在南中国海的海啸事件可能源于马尼拉俯冲带和沿岸断裂带诱发的地震的共同作用，以及南中国海北部的相关滑坡活动。

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引用次数: 0

Astronomically forced dynamics of Late Devonian (Famennian) sea level and biotic recovery in western Junggar, Northwest China 准噶尔西部晚泥盆世（法门世）海平面的天文强迫动态与生物恢复

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104677

Kunyuan Ma , Linda Hinnov , Zhihong Wang , Kai Wang , Ruiwen Zong , Xinsong Zhang , Junjun Song , Yang Bai , Yiming Gong

The Hongguleleng Formation in western Junggar, northwest China preserves a rich variety of fossils and was previously regarded as a “refugium” during the Late Devonian biotic crisis. Uncertainty in the age of the Hongguleleng Formation has persisted for a considerable time. In this study, cyclostratigraphic analysis was carried out on the Upper Devonian Bulongguoer and Wulankeshun sections from western Junggar, northwest China. Time series analysis and modeling of iron (Fe) concentration proxy data reveal variations with frequencies comparable to those of the Earth's long and short orbital eccentricity, obliquity, and precession index in both successions. Interpreted 405-kyr long orbital eccentricity cycles were used to establish floating astronomical time scales (FATs) for the two successions. From these FATs the depositional duration of the Hongguleleng Formation is calculated as 11.5 ± 0.58 Myr. The Devonian-Carboniferous boundary age of 359.3 ± 0.3 Ma was chosen as a time “anchor”, resulting in an astronomically determined age of 370.2 ± 0.66 Ma for the base of the Hongguleleng Formation. Combined with conodont biostratigraphy, this age indicates that the Hongguleleng Formation in western Junggar does not reach down to the Frasnian-Famennian boundary. Sedimentary noise modeling of the reconstructed Fe concentration time series provides an interpretation of sea-level variations in the Paleo-Asian Ocean controlled by astronomical forcing from very long orbital eccentricity cycles (g₄–g₃) throughout the Late Devonian period. Intensified monsoonal climates during these orbital eccentricity cycle maxima led to elevated terrigenous input and strengthened upwelling, which enhanced primary productivity in the western Junggar. We propose an “astronomical climate change” model as a driving mechanism that led to biotic recovery in the Famennian Hongguleleng Formation.

位于中国西北部准噶尔西部的红古楞地层保存了丰富的化石，曾被视为晚泥盆世生物危机时期的 "避难所"。红古楞地层的年代一直存在不确定性。本研究对中国西北准噶尔西部的上泥盆统布隆郭尔段和乌兰克顺段进行了旋回地层分析。通过对铁（Fe）浓度代用数据的时间序列分析和建模，发现这两个层位的变化频率与地球长短轨道偏心率、斜度和前向指数的变化频率相当。通过对 405 千年长轨道偏心率周期的解释，为两个演替建立了浮动天文时间尺度（FAT）。根据这些浮动天文时间尺度，计算出红古冷构造的沉积时间为 11.5 ± 0.58 Myr。泥盆纪-石炭纪的边界年龄为 359.3 ± 0.3 Ma，被选为时间 "锚"，从而得出红古楞地层底部的天文年龄为 370.2 ± 0.66 Ma。结合锥齿类生物地层学，这一年龄表明准噶尔西部的红古楞地层并没有到达新生代-新生代边界。通过对重建的铁元素浓度时间序列进行沉积噪音建模，可以解释整个晚泥盆世时期古亚洲洋的海平面变化受来自超长轨道偏心率周期（g4-g3）的天文作用的控制。在这些轨道偏心周期最大值期间，季风气候加剧，导致土著输入量增加，上升流增强，从而提高了准噶尔西部的初级生产力。我们提出的 "天文气候变化 "模型是导致法门寺红古楞地层生物恢复的驱动机制。

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引用次数: 0

Sedimentary responses to climatic variations and Kuroshio intrusion into the northern South China Sea since the last deglaciation 末次冰期以来南海北部对气候变化和黑潮入侵的沉积响应

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2024.104671

Chao Huang , Liyuan Wu , Jiansen Cheng , Xiaoxu Qu , Yongyi Luo , Huiling Zhang , Feng Ye , Gangjian Wei

The terrigenous sediment source-to-sink processes in marginal seas are governed by intricate interactions among climate, sea level, and ocean currents. The continental slope of the northern South China Sea (SCS) provides an excellent setting to examine these processes due to its substantial terrigenous influx and continuous sedimentation. In this study, we present a high-resolution sedimentary record from the northern SCS continental slope covering the last deglaciation. Analyses of Rare Earth Elements (REEs) and Sr–Nd isotopic compositions in the NH07 core indicate that the predominant source of terrigenous sediment was Taiwan. Grain size-standard deviation analysis identified two sensitive grain size components, with the sensitive component 2 used as a marker of the Kuroshio intrusion into the northern SCS through Luzon Strait. The intensity of the Kuroshio intrusion into the northern SCS was found to be inversely related to that of the open Pacific. The Asian monsoon and El Niño-Southern Oscillation (ENSO) significantly influenced the variability of the Kuroshio Current throughout the deglaciation period. During the interval 16, 000–11, 700 cal yr BP, variations in terrigenous influx were collectively driven by sea level changes and the intensity of the Kuroshio intrusion, while chemical weathering intensity was affected by the reworking of previously exposed shelf sediments due to sea level fluctuations. During the Holocene, however, the East Asian summer monsoon intensity became the primary factor influencing variations in terrigenous influx and chemical weathering.

边缘海的土著沉积物从源到汇过程受气候、海平面和洋流之间错综复杂的相互作用的支配。南中国海（SCS）北部的大陆坡因其大量的陆相沉积和持续的沉积作用，为研究这些过程提供了极佳的环境。在本研究中，我们展示了南中国海北部大陆坡涵盖末次脱冰期的高分辨率沉积记录。对NH07岩芯中稀土元素（REEs）和Sr-Nd同位素组成的分析表明，陆相沉积的主要来源是台湾。粒度标准偏差分析确定了两个敏感粒度分量，其中敏感分量 2 是黑潮通过吕宋海峡侵入南中国海北部的标志。研究发现，黑潮侵入南中国海北部的强度与开阔太平洋的强度成反比。亚洲季风和厄尔尼诺-南方涛动（ENSO）对黑潮在整个降冰期的变化有显著影响。在公元前16,000-11,700年期间，海平面变化和黑潮入侵强度共同驱动了土著涌入量的变化，而化学风化强度则受到海平面波动导致的先前裸露陆架沉积物再加工的影响。然而，在全新世期间，东亚夏季季风强度成为影响土著流入量和化学风化作用变化的主要因素。

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引用次数: 0

Testing and improving brGMGTs-based paleotemperature estimates in peat sediments: Evidence from global surface peat samples and two well-dated Holocene peat cores in far Northwest China 基于brgmgts的泥炭沉积物古温度估算的检验与改进：来自全球地表泥炭样品和中国西北远地区两个全新世泥炭岩心的证据

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2025.104700

Zhongwei Shen , Minghua Zhao , Tianyan Lin , Xiaoxu Qu , Haichun Guo , Jiantao Cao , Guodong Jia , Zhiguo Rao

BrGMGTs (branched glycerol monoalkyl glycerol tetraethers) are proposed as potential proxies for temperature estimation due to their constrained and consistent biological origin. However, discrepancies observed between brGMGTs-based proxies and MAAT (mean annual air temperature) have raised concerns about their applicability. Here, we analyzed surface samples from three peatlands across China, and two well-dated Holocene peat cores. We found: 1) surface peat samples showed that %brGMGTs (abundance of brGMGTs relative to brGMGTs and brGDGTs; brGDGTs: branched glycerol dialkyl glycerol tetraethers) and H-MBT (methylation degree of brGMGTs) were ineffective to represent temperature. 2) Holocene records of %brGMGTs and H-MBT were uncorrelated with MBT’_5ME records (previously established as reliable temperature records) in the same cores, as well as with regional other proxy temperature records. Our data, along with the global peat dataset, indicated that brGMGTs are ineffective for temperature estimation under cold conditions (MAAT <10 °C). This ineffectiveness may be due to unfavorable temperature niches, changes in aerobic/anaerobic conditions and microbial communities. By setting a threshold (%brGMGTs >4 %), we found that H-MBT showed a higher positive correlation with MAAT (R² = 0.50, p < 0.01, n = 26), compared to all samples (R² = 0.47, p < 0.01, n = 72). Although this improvement in correlation is modest, it helps exclude samples with MAAT <10 °C. Our revised method for temperature estimation using brGMGTs could potentially be applied to peat sediments with MAAT ranging from 10 °C to 27 °C, enhancing their application for paleotemperature reconstruction in future research.

BrGMGTs（支链甘油单烷基甘油四醚）由于其受约束和一致的生物来源而被提出作为温度估计的潜在代理。然而，基于brgmgts的代用物与MAAT（年平均气温）之间观测到的差异引起了人们对其适用性的担忧。在这里，我们分析了来自中国三个泥炭地的地表样本，以及两个年代确定的全新世泥炭岩心。结果表明：1)表层泥炭样品中brGMGTs（相对于brGMGTs和brGMGTs的丰度）%；brGMGTs：支化甘油二烷基甘油四醚)和H-MBT （brGMGTs的甲基化程度）不能代表温度。2)全新世的% brgmgt和H-MBT记录与同一岩心的MBT’5ME记录（以前建立的可靠温度记录）以及区域其他代理温度记录不相关。我们的数据以及全球泥炭数据表明，在寒冷条件下（MAAT <10°C）， brGMGTs对温度估计无效。这种无效可能是由于不利的温度生态位，好氧/厌氧条件和微生物群落的变化。通过设置阈值（%brGMGTs > 4%），我们发现H-MBT与MAAT有较高的正相关(R2 = 0.50, p <；0.01, n = 26)，与所有样本相比(R2 = 0.47, p <；0.01, n = 72)。虽然这种相关性的改善是适度的，但它有助于排除MAAT <；10°C的样品。修正后的brGMGTs温度估算方法可应用于MAAT范围为10 ~ 27℃的泥炭沉积物，增强了其在未来研究中古温度重建的应用价值。

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引用次数: 0

Glacial-interglacial changes in Antarctic Intermediate Water advection in the Southeast Pacific during the last 787 kyr 过去787年东南太平洋南极中水平流的冰期-间冰期变化

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-02-01 DOI: 10.1016/j.gloplacha.2025.104695

Karol O. Duarte , Igor M. Venancio , Rodrigo A. Nascimento , Ana Luiza S. Albuquerque , Thiago P. Santos , Stefano Crivellari , Cristiano M. Chiessi , IODP Expedition 383 Shipboard Scientists

Southern-sourced intermediate waters play a central role in global ocean oxygenation and nutrient transport to low latitudes. However, the glacial-interglacial variability in their formation rate and geometry are not well constrained. Here we present a new ca. 787 thousand years-long benthic foraminifera stable carbon isotopic record from the Southeast Pacific, near the main formation region of Antarctic Intermediate Water (AAIW), which allows the investigation of changes in the formation rate and transport of AAIW over the last 787 kyr. Our results show glacial-interglacial changes in AAIW transport, with more AAIW being exported towards the Atlantic Ocean during interglacials, and to the low-latitude Pacific Ocean during glacials. We hypothesize that the AAIW exportation from the Pacific to the Atlantic Ocean is controlled by transport through the Drake Passage, which is reduced (increased) during glacial (interglacial) periods. The observed pattern is probably related to a combination of factors, including reduced (increased) sea-ice extent and southward (northward) shift of oceanic fronts and/or the westerlies during interglacials (glacials). Our mechanism reconciles the greater influence of AAIW in the northern Chilean margin during glacial periods, concurrent with the previously suggested decrease in formation rate and shallowing of this water mass. Ultimately, the glacial-interglacial variability in AAIW exportation to the Atlantic Ocean may be closely linked with changes in the stability of Atlantic Meridional Overturning Circulation during these distinct climate background states.

南源中间水在全球海洋含氧和向低纬度地区输送营养物质的过程中发挥着核心作用。然而，它们的形成速度和几何形状在冰川-冰川间的变化并没有得到很好的解释。在此，我们从南极中层水（AAIW）的主要形成区域附近的东南太平洋地区获得了长达约 78.7 万年的新的底栖有孔虫稳定碳同位素记录，从而可以研究过去 78.7 万年中南极中层水的形成速率和传输的变化。我们的研究结果显示了冰期-间冰期AAIW迁移的变化，在间冰期有更多的AAIW向大西洋输出，而在冰期则向低纬度太平洋输出。我们假设，从太平洋向大西洋输出的 AAIW 受控于通过德雷克海峡的传输，而在冰川期（间冰期），德雷克海峡的传输会减少（增加）。观测到的模式可能与多种因素有关，包括海冰范围缩小（增大）、大洋锋面和/或西风在间冰期南移（北移）。在冰川期，AAIW 对智利北部边缘的影响更大，与此同时，之前提出的该水团的形成率下降和变浅的情况也得到了调和。最终，冰川-间冰期向大西洋输出 AAIW 的变化可能与这些不同气候背景状态下大西洋经向翻转环流稳定性的变化密切相关。

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引用次数: 0