Palaeogeography, Palaeoclimatology, Palaeoecology最新文献_第3页

Magmatic source effects on Zircon Eu anomalies: Refining the Late Cretaceous–Eocene uplift of the Gangdese Arc, Southern Tibet 岩浆源对锆石Eu异常的影响：对藏南冈底斯弧晚白垩世-始新世隆升的精炼

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-27 DOI: 10.1016/j.palaeo.2026.113602

Guang-Sheng Ren, Jin-Gen Dai, Xiang-Rui Liu, Xu Han, Bo-Rong Liu, Jia-Qi Sun

The surface uplift history of the Gangdese Arc is critical for understanding tectonic and paleoenvironmental evolution of the southern Tibetan Plateau. While zircon Eu anomalies (Eu/Eu*) are widely used to infer crustal thickness and paleoelevation, their reliability is often compromised by heterogeneity in magma sources. Here we compile and analyze detrital and magmatic zircon Eu anomaly (Eu/Eu*) data from the Gangdese Arc. By applying rigorous screening to exclude S-type granitic zircons and analyzing distribution patterns, we identified pronounced bimodal Eu/Eu* values often mask critical geological signals: high values (∼0.51) at 100–80 Ma reflect the partial melting of eclogitized oceanic crust (source-controlled enrichment), while low values (∼0.22) at 65–40 Ma indicate crustal assimilation. By isolating these source-biased subpopulations, we reconstruct robust histories of crustal thickness and paleoelevation. Results indicate the Gangdese Arc underwent a major uplift phase during 80–70 Ma, reaching 3.0–4.0 km prior to the India–Asia collision, and maintained high elevations through 65–40 Ma. This revised uplift history is consistent with regional paleoclimate records and independent paleoaltimetric proxies. Our results highlight that magma source heterogeneity exerts an important control on zircon Eu/Eu* signatures. Accounting for such magmatic effects is essential for reliable crustal thickness reconstructions and for refining tectonic and paleoenvironmental interpretations of continental arcs worldwide.

冈底斯弧的地表隆升史对认识青藏高原南部构造和古环境演化具有重要意义。虽然锆石Eu异常（Eu/Eu*）被广泛用于推断地壳厚度和古海拔，但其可靠性往往受到岩浆源非均质性的影响。本文对Gangdese弧碎屑和岩浆锆石Eu异常（Eu/Eu*）数据进行了整理和分析。通过严格筛选排除s型花岗质锆石并分析其分布模式，我们发现明显的双峰Eu/Eu*值往往掩盖了关键的地质信号：100-80 Ma的高值（~ 0.51）反映了榴辉化海洋地壳的部分熔融（源控富集），而65-40 Ma的低值（~ 0.22）表明地壳同化。通过分离这些源偏倚的亚种群，我们重建了地壳厚度和古海拔的稳健历史。结果表明，Gangdese弧在印度-亚洲碰撞前80 ~ 70 Ma经历了一次大的隆升阶段，达到3.0 ~ 4.0 km，并在65 ~ 40 Ma期间保持高海拔。这一修正的隆升历史与区域古气候记录和独立的古高程代用物相一致。岩浆源非均质性对锆石Eu/Eu*特征具有重要的控制作用。对于可靠的地壳厚度重建，以及对世界范围内大陆弧的构造和古环境解释的精细化，这种岩浆作用的计算是必不可少的。

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引用次数: 0

Abyssal record of the Middle Eocene Climatic Optimum in the Tasman Sea: Insights from benthic foraminiferal and clay mineral assemblages 塔斯曼海中始新世气候最佳的深海记录：来自底栖有孔虫和粘土矿物组合的见解

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-27 DOI: 10.1016/j.palaeo.2026.113590

Irene Peñalver-Clavel , Elisa Laita , Edoardo Dallanave , Rupert Sutherland , Gerald R. Dickens , Thomas Westerhold , Blanca Bauluz , Laia Alegret

The Middle Eocene Climatic Optimum (MECO), a ∼500 kyr global warm interval at ∼40 Ma, interrupted the gradual cooling trend of the mid-late Eocene. Unlike Eocene hyperthermal events with rapid onsets and slow recoveries, the MECO began gradually, ended swiftly, and lacked a global negative carbon isotope excursion, raising questions about warming‑carbon cycling links. Here we report for the first time the response of benthic foraminifera, which are excellent palaeoenvironmental proxies, across the MECO at abyssal depths, integrating our results with a mineralogical analysis of the sediment.

International Ocean Discovery Program Site U1511 (Tasman Abyssal Plain, SW Pacific) was deposited below the carbonate compensation depth during the Eocene, and calcareous microfossils are absent. Agglutinated benthic foraminifera indicate a gradual onset of the environmental perturbations associated with the MECO, followed by rapid recovery. Changes in their assemblages, including the temporary disappearance of Lazarus taxa, the decreased abundance of suspension feeders and dominance of opportunistic detritivores, indicate weaker bottom-water currents during MECO and increased stratification of the water column. Mineralogical changes reinforce this interpretation, with increased smectite content indicating warm, humid conditions in the source-area, and possibly a change in the deep-water source. The reappearance of Lazarus taxa after the MECO indicates rapid recovery of deep-sea environmental conditions.

The comparison of Site U1511 with available studies from other regions reveals the complex and regionally diverse nature of benthic foraminiferal response to the MECO, emphasizing the critical role of ocean circulation and palaeogeography during Eocene warm intervals.

中始新世气候最适期（MECO）是一个约500 kyr的全球变暖间隔，约40 Ma，中断了始新世中后期的逐渐变冷趋势。与始新世开始迅速、恢复缓慢的高温事件不同，MECO开始缓慢，结束迅速，缺乏全球负碳同位素偏移，这引发了关于变暖与碳循环联系的问题。在这里，我们首次报道了底栖有孔虫的反应，这是一种优秀的古环境代用物，在深海深处横跨MECO，将我们的结果与沉积物的矿物学分析相结合。国际海洋发现计划遗址U1511（西南太平洋Tasman深海平原）沉积于始新世碳酸盐补偿深度以下，缺乏钙质微化石。凝集的底栖有孔虫表明与MECO相关的环境扰动逐渐开始，随后迅速恢复。它们组合的变化，包括Lazarus类群的暂时消失、悬浮食性动物丰度的减少和机会性腐食动物的优势，表明MECO期间底水流减弱，水体分层加剧。矿物学变化强化了这一解释，蒙脱石含量的增加表明源区温暖潮湿，可能是深水源区的变化。在MECO之后，Lazarus分类群的重新出现表明深海环境条件的迅速恢复。U1511站点与其他地区已有研究的对比揭示了底栖有孔虫对MECO响应的复杂性和区域多样性，强调了始新世暖期海洋环流和古地理的关键作用。

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引用次数: 0

New tuff constraints on episodic volcanism and consequent carbon sequestration during the Ediacaran-Cambrian transition in South China 华南埃迪卡拉-寒武纪过渡时期幕式火山作用及其碳封存的新凝灰岩约束

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-26 DOI: 10.1016/j.palaeo.2026.113605

Zhen Yang , Yong Fu , Zongxiang Zhang

Tuffs (or K-bentonites) were widely developed in South China during the Ediacaran–Cambrian (E-C) transition. These volcaniclastic layers are typically intercalated within dolostones and phosphorites in Yunnan, whereas they occur primarily within cherts in Guizhou and Hunan. They are often overlain by black shale series, overall. An integrated geochemical and geochronological study has been conducted on tuff layers from two continuous deep-water sedimentary successions in South China, in order to examine the influence of volcanic activity on the paleoenvironment and its potential role as a carbon-sink trigger. Samples were collected from the middle Liuchapo Formation at the Bahuang section (Tongren) and from the topmost Liuchapo Formation at the Yacha section (Sansui). Analytical work included whole-rock major and trace elements, zircon UPb dating and trace elements, and LuHf isotopic analysis. The study reveals that the zircon crystallization age of the Bahuang tuff is 549.9 ± 2.0 Ma (MSWD =0.28), and that of the Yacha tuff is 513.4 ± 2.1 Ma (MSWD =0.07). The zircon ε_Hf(t) values of the Bahuang tuff are predominantly negative, ranging from −5.17 to 2.77, while those of the Yacha tuff range from −0.71 to 4.67. Indicates that the magmatic sources for both the Bahuang and Yacha tuffs were derived from the mantle and juvenile lower crust, with the Bahuang tuff incorporating a greater proportion of ancient crustal material. The magmatic oxygen fugacity of both the Bahuang and Yacha tuffs was relatively lower, with Yacha tuff exhibiting slightly higher values than Bahuang tuff. The influence of oxygen fugacity on carbon sedimentation appears insignificant. Following the volcanic activity, these parameters K₂O, Al₂O₃, and ^TFe₂O₃ of black shale showed significant increases, with TOC exhibiting a clear positive correlation. This demonstrates that volcanic activity introduced nutrients such as Fe, K, Ca, and P, thereby enhancing paleo-productivity and facilitating the enrichment of organic carbon. This indicates that volcanic activity during the E-C transition acted as a trigger for enhanced carbon sinks.

在埃迪卡拉-寒武纪（E-C）过渡时期，华南地区广泛发育凝灰岩（或称k -膨润土）。这些火山碎屑层在云南主要穿插于白云岩和磷岩中，而在贵州和湖南主要穿插于燧石中。总的来说，它们通常被黑色页岩系列覆盖。摘要对华南两个连续深水沉积序列的凝灰岩层进行了地球化学和年代学综合研究，探讨了火山活动对古环境的影响及其作为碳汇触发因素的潜在作用。样品采集于铜仁坝黄剖面中六寨坡组和三穗崖崖剖面中六寨坡组顶部。分析工作包括全岩主量元素和微量元素、锆石UPb定年和微量元素、LuHf同位素分析。研究表明，巴皇凝灰岩的锆石结晶年龄为549.9±2.0 Ma (MSWD =0.28)，崖崖凝灰岩的锆石结晶年龄为513.4±2.1 Ma （MSWD =0.07）。巴黄凝灰岩的锆石εHf(t)值为- 5.17 ~ 2.77，雅恰凝灰岩的锆石εHf(t)值为- 0.71 ~ 4.67。表明巴皇凝灰岩和崖恰凝灰岩的岩浆源均来自地幔和幼年下地壳，其中巴皇凝灰岩含古地壳物质的比例较大。巴皇凝灰岩和崖崖凝灰岩的岩浆氧逸度相对较低，崖崖凝灰岩略高于巴皇凝灰岩。氧逸度对碳沉降的影响不明显。火山活动后，黑色页岩的K₂O、Al₂O₃、TFe₂O₃等参数显著增加，与TOC呈明显的正相关。这表明火山活动引入了铁、钾、钙、磷等营养物质，从而提高了古生产力，促进了有机碳的富集。这表明，E-C转换期间的火山活动是碳汇增强的触发因素。

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引用次数: 0

Sharp rise in cormorant (Phalacrocorax auritus) populations on Lake Ontario islands inferred from analyses of pond sediment cores 从池塘沉积物岩心分析推断，安大略湖岛屿上鸬鹚（Phalacrocorax auritus）种群急剧上升

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-25 DOI: 10.1016/j.palaeo.2026.113603

Daniel Dagodzo , David C. Eickmeyer , Linda E. Kimpe , John P. Smol , Jules M. Blais

We measured biomarkers in pond sediment cores to infer population dynamics and track the ecological impacts of cormorants at East Brother Island (EBI), a cormorant-affected site, and Calf Island (CI), a reference site, in Lake Ontario over the past ∼170 years. Pronounced synchronous increases in cholesterol, cholestanol, cholestanone, coprostanol, epicoprostanol concentrations, expanded bird sterol index (EBSI), and δ¹⁵N values in the 1970s mark the establishment and rapid expansion of cormorant colonies at EBI. That time coincides with human-mediated environmental changes such as the regulation of organochlorine contaminants (e.g. DDT, PCBs), later introduction of invasive fish species, and reduced human disturbances. Declining C:N ratios and an initial increase in the plant stanol stigmastanol at EBI, following the initial colony establishment reflect short-term enhancement of terrestrial primary productivity driven by guano deposition. However, stigmastanol concentrations declined after ca. 1990, likely from vegetation degradation caused by the toxic effects of ammonia-rich guano and physical disturbances from bird nesting activities. We document the transformative impacts of cormorant populations on nutrient cycling, sediment processes, and vegetation dynamics at their nesting sites, providing a detailed record of how waterbird populations modify ecosystems over time, following their arrival. The findings highlight the value of integrating long-term ecological monitoring and adaptive management strategies to address the impacts of expanding waterbird populations, particularly in sensitive lacustrine environments.

我们测量了池塘沉积物岩心中的生物标志物，以推断种群动态，并跟踪过去~ 170年来在安大略湖的东兄弟岛（EBI）和小牛岛（CI）的鸬鹚影响点的生态影响。在20世纪70年代，胆固醇、胆固醇、胆甾酮、coprostanol、表前列腺醇浓度、扩展鸟固醇指数（EBSI）和δ15N值同步上升，标志着鸬鹚群落在EBI的建立和快速扩张。这段时间恰逢人类介导的环境变化，如对有机氯污染物（如滴滴涕、多氯联苯）的管制、后来引入入侵鱼类以及人为干扰减少。在EBI，随着初始群落的建立，C:N比率的下降和植物甾醇的初始增加反映了鸟粪沉积驱动的陆地初级生产力的短期增强。然而，大约在1990年之后，豆甾醇浓度下降，可能是由于富氨鸟粪的毒性作用和鸟类筑巢活动的物理干扰引起的植被退化。我们记录了鸬鹚种群对其筑巢地的营养循环、沉积物过程和植被动态的变革性影响，详细记录了水鸟种群在其到达后如何随时间改变生态系统。研究结果强调了将长期生态监测和适应性管理策略相结合的价值，以解决水鸟种群数量增加的影响，特别是在敏感的湖泊环境中。

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引用次数: 0

Cave deposits U-Pb chronology: insights into the timing of Myotragus antiquus, cave evolution, and Pliocene sea level in Mallorca 马略卡岛洞穴沉积物U-Pb年代学：对Myotragus古恐龙时代、洞穴演化和上新世海平面的见解

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-25 DOI: 10.1016/j.palaeo.2026.113604

Oana A. Dumitru , Angel Ginés , Victor J. Polyak , Joaquín Ginés , Pere Bover , Joan J. Fornós , Yemane Asmerom , Bogdan P. Onac

Cave deposits represent critical archives for reconstructing the timing of faunal evolution, speleogenesis, and sea-level change in coastal settings. Here, we present the first uranium‑lead (U-Pb) geochronological framework for the fossil-rich stratigraphy of Cova des Fum, Mallorca, offering new constraints on the age of the extinct goat Myotragus antiquus, the cave's speleogenetic history, and Pliocene sea-level history. Flowstone samples collected above and below a bone-bearing breccia yielded ages between 3.60 ± 0.77 Ma and 3.45 ± 0.68 Ma, placing the deposition of M. antiquus remains within the Late Pliocene. A basal flowstone age of 4.70 ± 0.55 Ma suggests that cave development began in the late Miocene, consistent with broader models of early speleogenesis in coastal eastern Mallorca. The stratigraphic succession, which includes interbedded aeolian calcarenites, suggests episodic sediment influx into a cave system already disconnected from active drainage. These flowstone ages, from an elevation of ∼82 m above present sea level, serve as terrestrial limiting points for sea-level reconstruction and align with other local estimates of Pliocene sea level derived from phreatic overgrowth on speleothems. By showing that M. antiquus is nearly one million years older than previously thought, this study provides the oldest well-resolved chronological constraints for the species, refines the timing of speleogenetic phases, and contributes new indirect evidence for Pliocene sea levels in the western Mediterranean.

洞穴沉积物是重建沿海地区动物进化、洞穴形成和海平面变化时间的重要档案。在这里，我们提出了马略卡岛Cova des Fum富化石地层的第一个铀铅（U-Pb）地质年代学框架，为灭绝山羊Myotragus antiquus的年龄、洞穴的洞穴形成历史和上新世海平面历史提供了新的限制。在含骨角砾岩上方和下方采集的流石样本的年龄在3.60±0.77 Ma至3.45±0.68 Ma之间，表明古m.a antiquus的沉积时间为晚上新世。基底流岩年龄为4.70±0.55 Ma，表明洞穴发育始于中新世晚期，与马略卡岛东部沿海地区早期洞穴形成的广泛模式相一致。地层演替，包括互层的风成钙质，表明幕式沉积物流入已经与活动排水系统断开的洞穴系统。这些流石年龄来自于高于目前海平面约82米的海拔高度，可作为海平面重建的陆地限制点，并与其他当地根据洞穴上的潜水过度生长得出的上新世海平面估计相一致。通过表明古猿古猿比之前认为的要早近100万年，这项研究为该物种提供了最古老的时间限制，完善了洞穴形成阶段的时间，并为地中海西部上新世海平面提供了新的间接证据。

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引用次数: 0

Multi-system geochronometer constraints on thermo-tectonic evolution of the Qiangtang Terrane, central Tibetan Plateau: Comment 青藏高原中部羌塘地体热构造演化的多系统年表约束

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-24 DOI: 10.1016/j.palaeo.2026.113582

Xiao-Long Song , Ru-Ye Tian , Kang-Yu Li

The elevation of the Tibetan Plateau constitutes a revolutionary event in Earth's history, but the chronologic evolution and mechanistic drivers of plateau formation persist as subjects of intense contention. Recently, Lei et al. (2026) proposed that the Tibetan Plateau underwent pulse-like growth and that the rapid elevation of the Qiangtang block during the 120–90 Ma due to the Lhasa–Qiangtang continental collision. However, the extensive literature records of Cretaceous marine deposition over the Qiangtang block does not support its rapid elevation during 120–90 Ma and studies reveal that the subduction of the Meso- and Neo-Tethys oceanic lithospheres could have played a critical role in the initial elevation of the Qiangtang and Lhasa blocks prior to the Cenozoic Indo–Asian collision. An insufficient incorporation of regional sedimentary, structural and tectonic data under over-reliance on limited thermochronological data has seriously undermined the soundness and reliability of Lei et al.'s work.

青藏高原的上升是地球历史上的一个革命性事件，但高原形成的年代学演变和机制驱动因素仍然是激烈争论的主题。最近，Lei et al.（2026）提出青藏高原经历了脉冲式生长，羌塘地块在120-90 Ma期间的快速抬升是由于拉萨-羌塘大陆碰撞。然而，白垩纪海相沉积在羌塘地块上的大量文献记录并不支持其在120-90 Ma期间的快速抬升，研究表明中、新特提斯洋岩石圈的俯冲作用可能在新生代印亚碰撞之前的羌塘和拉萨地块的初始抬升中发挥了关键作用。由于过度依赖有限的热年代学资料，没有充分结合区域沉积、构造和构造资料，严重影响了Lei等人工作的可靠性和可靠性。

引用次数: 0

Different responses of stalagmite oxygen and carbon isotopes reveal interhemispheric phasing of climate during the Marine Isotope Stage 4 to 3 transition 石笋氧和碳同位素的不同响应揭示了海洋同位素阶段4 - 3的半球间气候相变

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-24 DOI: 10.1016/j.palaeo.2026.113580

Gong-Zhe Chen , Hao-Xiang Huang , Shi-Tao Chen , Shu Yang , Zhen-Jun Wang , Yong-Jin Wang , Xian-Feng Wang

Chronological uncertainties in paleoclimate records continue to obscure the interhemispheric phasing and driving mechanisms of Dansgaard–Oeschger (DO) events during the last glacial period. This study presents a high-precision ²³⁰Th-dated stalagmite record (YX53) from Yongxing Cave in central China, spanning 64.4–52.5 ka B.P. and covering DO events 18 to 14. The results show that variations in stalagmite δ¹⁸O, align closely in event structure with records of tropical precipitation, Intertropical Convergence Zone position, and Antarctic temperature, indicating a tropical–Southern Hemisphere climatic signal. In contrast, the δ¹³C record exhibits a pattern similar to Greenland temperature and dust variations, suggesting a primary response to North Atlantic climate variability. By analyzing the phase relationship between δ¹⁸O and δ¹³C within the same stalagmite, this study directly evaluates the relative timing of these climate signals under a unified chronology. We further improved the objectivity of the phase analysis by applying sub-decadal sampling, stricter statistical criteria, and intra-cave cross-validation. Results show that during the onset of DO events, changes in δ¹³C did not lag behind those in δ¹⁸O. This indicates that North Atlantic climate change was not delayed relative to tropical and Southern Hemisphere responses on decadal timescales, challenging the hypothesis of a Southern Hemisphere pacemaker for abrupt events during the Marine Isotope Stage 4 to 3 transition.

末次冰期Dansgaard-Oeschger （DO）事件的半球间相位和驱动机制在古气候记录中的不确定性继续模糊不清。本文研究了中国中部永兴洞230年代的高精度石笋记录（YX53），时间跨度为64.4 ~ 52.5 ka B.P.，涵盖DO事件18 ~ 14。结果表明，石笋δ18O的变化在事件结构上与热带降水、热带辐合带位置和南极温度记录密切一致，表明存在热带-南半球气候信号。相比之下，δ13C记录表现出与格陵兰岛温度和尘埃变化相似的模式，表明对北大西洋气候变率的主要响应。通过分析同一石笋内δ18O和δ13C的相位关系，直接评价了这些气候信号在统一年代学下的相对时序。通过采用次年代际采样、更严格的统计标准和洞内交叉验证，进一步提高了相分析的客观性。结果表明，在DO事件开始时，δ13C的变化不滞后于δ18O的变化。这表明，在年代际尺度上，北大西洋的气候变化相对于热带和南半球的响应并没有延迟，这挑战了在海洋同位素第4到第3阶段转变期间，南半球是突变事件的起搏器的假设。

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引用次数: 0

Weathering of the Gangdese Mountains and its impact on Paleogene seawater 87Sr/86Sr evolution 冈底斯山脉风化作用及其对古近系海水87Sr/86Sr演化的影响

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-24 DOI: 10.1016/j.palaeo.2026.113581

Xiaobai Ruan , Albert Galy

In this paper, the Sr geochemistry of rivers draining the eastern part of the Gangdese Mountains is used as an analogue to understand the contribution of this region to seawater ⁸⁷Sr/⁸⁶Sr ratios over the last 40 Ma. Dissolved Sr in the Chayu River Basin is radiogenic (⁸⁷Sr/⁸⁶Sr = 0.7313–0.7339) and more radiogenic compared to the adjacent Parlung Tsangpo Basin (0.7135–0.7174). In both basins, particulate detrital carbonates exhibit ⁸⁷Sr/⁸⁶Sr ratios consistent with the dissolved load. High dissolved K/Si ratios reflect the weathering of Rb-bearing minerals, yet their lack of covariation with ⁸⁷Sr/⁸⁶Sr ratios rules out silicate weathering as the driver of the radiogenic signal. Instead, this radiogenic Sr flux in the Chayu River Basin likely derives from the weathering of disseminated calcite. Disseminated calcite in granitoids of the eastern Gangdese Mountains, formed by melting during collision, records the mobilization of ⁸⁷Sr from less weatherable silicates into highly weatherable phases. Meanwhile, in the Parlung Tsangpo Basin, the less radiogenic signatures likely corresponds to the erosion and weathering of massive marine carbonate rocks that occur widely across that region. We infer that the Paleogene weathering of the radiogenic disseminated calcite within the eastern Gangdese and equivalent batholiths of the Lhasa, Tengchong and Sibumasu blocks likely triggered the rise in seawater ⁸⁷Sr/⁸⁶Sr at ∼40 Ma.

本文以冈底斯山脉东部河流的Sr地球化学为模拟物，研究了该地区近40 Ma来对海水87Sr/86Sr比值的贡献。察峪河流域溶解Sr具有放射性成因（87Sr/86Sr = 0.7313 ~ 0.7339），与邻近的帕隆羌布盆地（0.7135 ~ 0.7174）相比更具放射性成因。在两个盆地中，颗粒碎屑碳酸盐的87Sr/86Sr比值与溶解负荷一致。高溶解K/Si比值反映了含rb矿物的风化作用，但它们与87Sr/86Sr比值缺乏共变，排除了硅酸盐风化作为放射性成因信号驱动因素的可能性。察余河流域放射性成因的锶通量可能来源于浸染方解石的风化作用。冈底斯山脉东部花岗岩类中的浸染方解石是在碰撞过程中熔融形成的，记录了87Sr从不耐候硅酸盐向高耐候相的运移过程。同时，在帕隆藏布盆地，较少的放射性成因特征可能与广泛分布于该地区的块状海相碳酸盐岩的侵蚀和风化相对应。我们推测，冈底斯东部放射成因浸染方解石的古近系风化作用以及拉萨、腾冲和西布马苏地块的等效岩基可能引发了海水87Sr/86Sr在~ 40 Ma的升高。

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引用次数: 0

AI-driven quantitative classification of tropical cyclone intensity using Tridacna daily growth bands 利用Tridacna日增长带对热带气旋强度进行人工智能驱动的定量分类

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-24 DOI: 10.1016/j.palaeo.2026.113573

Qiuju Yang , Jianmiao Liao , Nanyu Zhao , Chengcheng Liu , Hong Yan

Understanding long-term tropical cyclone (TC) evolution requires high-resolution paleoclimate records at daily scales. Traditional proxies such as corals and sediments lack the resolution to resolve individual events. Although Tridacna shells exhibit daily growth bands with sub-weekly resolution, manual analysis of laser scanning confocal microscopy (LSCM) images is time-consuming and subjective, limiting their application for quantitative reconstructions. This study introduces an artificial intelligence (AI) framework to address these challenges. A dual-task generative adversarial network (DT-GAN) enhances LSCM image quality and enables precise segmentation of Tridacna daily growth bands. This approach improves processing efficiency by over five orders of magnitude compared to manual methods. By automatically extracting key features related to the daily growth increments and fluorescence intensity, we employ a long short-term memory (LSTM) network to classify TC intensity at daily resolution. Applied to a modern T. squamosa specimen from the South China Sea (2012−2013), our model achieved an accuracy of 85.14% in detecting TC occurrence and 81.71% in classifying seven intensity grades (0–6). This work establishes the first quantitative model linking Tridacna growth band features to TC activity, providing a robust methodological foundation for high-resolution paleotempestology using fossil shells.

了解热带气旋（TC）的长期演变需要高分辨率的日尺度古气候记录。珊瑚和沉积物等传统的代用物缺乏解决单个事件的分辨率。尽管砗磲蛤壳呈现出亚周分辨率的日生长带，但激光扫描共聚焦显微镜（LSCM）图像的人工分析既耗时又主观，限制了它们在定量重建中的应用。本研究引入了一个人工智能（AI）框架来应对这些挑战。一种双任务生成对抗网络（DT-GAN）提高了LSCM图像质量，实现了Tridacna日常生长带的精确分割。与手工方法相比，这种方法将处理效率提高了五个数量级以上。通过自动提取与日生长增量和荧光强度相关的关键特征，我们采用长短期记忆（LSTM）网络对日分辨率下的TC强度进行分类。应用于现代t squamosa标本从南海(2012−2013),我们的模型实现了85.14%的准确性检测TC发生和分类七81.71%强度等级(- 6)。本研究建立了第一个将砗磲生长带特征与TC活动联系起来的定量模型，为利用化石壳进行高分辨率古风暴学研究提供了坚实的方法基础。

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引用次数: 0

The inverse temperature effect of precipitation stable isotopes poses a challenge to the paleoclimate reconstructions 降水稳定同位素的逆温度效应对古气候重建提出了挑战

IF 2.7 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2026-01-23 DOI: 10.1016/j.palaeo.2026.113587

Baijun Shang , Tong Li , Hui Gao , Feng Wang , Tonggang Fu

Stable isotopes (δ¹⁸O and δD) in precipitation have long served as key proxies for paleoclimate reconstructions under the assumption of a universal temperature effect (TE), where isotopic enrichment correlates with warming. However, this study identifies clear inverse temperature effects (ITE)—where isotopic depletion accompanies higher temperatures—across different climate types and time scales. Analyzing global precipitation isotope data, this study finds that low-latitude regions exhibit significant monthly-scale ITE, expressed as a δ¹⁸O-temperature regression slope (δ-T_ITE) down to −0.46 ‰/°C in Tropical summer. Conversely, high latitudes (> 40°N) maintain a clear TE, with a δ¹⁸O-temperature regression slope (δ-T_TE) up to 0.44 ‰/°C in Polar climate. The spatiotemporal variability in TE/ITE is driven by atmospheric circulation patterns: monthly-scale ITE in monsoon regions may be linked to moisture source shifts and convective precipitation dominance, whereas TE in high latitudes reflects direct temperature control on isotopic fractionation during condensation. Seasonal/interannual scales show weakened or insignificant TE/ITE in mid-low latitudes due to modulating effects of ENSO, monsoon dynamics, and the Intertropical Convergence Zone (ITCZ), which introduce other drivers like precipitation amount and vapour recycling. These results demonstrate that ignoring time-scale and climate-type dependencies may lead to unreliable paleoclimate reconstructions, while the identification of the ITE of stable isotopes provides a new perspective for stable-isotope based paleoclimate reconstruction research.

长期以来，稳定同位素（δ18O和δD）一直是在普遍温度效应（TE）假设下重建古气候的关键指标，其中同位素富集与变暖有关。然而，这项研究在不同的气候类型和时间尺度上确定了明确的逆温度效应（ITE）——同位素耗竭伴随着更高的温度。分析全球降水同位素资料发现，低纬度地区表现出显著的月尺度ITE，表现为热带夏季δ18 -温度回归斜率（δ-TITE）降至- 0.46‰/°C。相反，高纬度地区（> 40°N）保持明显的TE，极地气候δ18 -温度回归斜率（δ-TTE）高达0.44‰/°C。TE/ITE的时空变化受大气环流模式驱动：季风区月尺度的TE可能与水汽源转移和对流降水优势有关，而高纬度地区的TE反映了凝结过程中温度对同位素分馏的直接控制。在季节/年际尺度上，由于ENSO、季风动力和热带辐合带（ITCZ）的调制作用，中低纬度地区的TE/ITE减弱或不明显，而热带辐合带引入了降水和蒸汽再循环等其他驱动因素。这些结果表明，忽略时间尺度和气候类型依赖关系可能导致古气候重建不可靠，而稳定同位素ITE的识别为基于稳定同位素的古气候重建研究提供了新的视角。

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