Palaeogeography, Palaeoclimatology, Palaeoecology最新文献_第5页

Extensive Oceanic Anoxia during the early Cambrian: Evidence from Mn-Carbonate and Alabandite Deposition in the Northwestern Yangtze margin, South China 寒武纪早期大洋缺氧：华南西北部长江边缘碳酸锰和白云石沉积的证据

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-09 DOI: 10.1016/j.palaeo.2024.112549

Yi Zhang , Zhiwei Liao , Qin Huang , Zhijie Xu , Lidan Lei , Jinjiang Pan

The Cambrian Explosion, which is characterized by complex organisms radiation after ∼521 Ma, has led to speculation about low levels of ocean oxygenation during the Early Cambrian (∼541–521 Ma). Recently, the genesis of sedimentary Mn-deposits has provided a new perspective for understanding the redox status of ancient oceans. The present study reevaluates the redox conditions of the Early Cambrian Ocean in South China using sedimentary records of Mn-deposits. The Mn-deposits developed in the Lower Cambrian Qiujiahe Formation on the northwestern Yangtze margin, covering slope/basin-to-shelf environments. The combined sedimentological, mineralogical, and geochemical evidence indicates that Mn-deposits lack of Mn-oxide precursors and exhibited hydrothermal-type REE patterns and δ¹³C distributions. Mn‑carbonates and partially alabandite (MnS) were directly precipitated in Mn-rich anoxic waters. The Mn-bearing rocks exhibited high total organic matter content (TOC, average 3.96 %), and pyrite layers developed, indicating active anaerobic sulfate reduction with the removal of Fe before Mn-deposition. The increased of the pH and sulfurization degree, promoting the Mn-minerals precipitation in water columns. The widespread Mn deposition across slope/basin-to-shelf areas represents the sedimentary response to the extensive ocean anoxia during the Early Cambrian. Such a scenario aids in elucidating the evolution of early life, suggesting that extensive ocean anoxia likely contributed to delaying the radiation of complex animals during the Cambrian Explosion.

寒武纪大爆发的特点是在∼521Ma之后辐射出复杂的生物，这导致了对早寒武纪（∼541-521Ma）海洋低含氧量的猜测。最近，沉积锰沉积物的成因为了解古海洋的氧化还原状态提供了一个新的视角。本研究利用沉积锰沉积记录重新评价了华南早寒武纪海洋的氧化还原状况。锰沉积发育于长江西北缘下寒武统邱家河组，覆盖了斜坡/盆地-陆架环境。沉积学、矿物学和地球化学的综合证据表明，锰沉积缺乏锰氧化物前驱体，表现出热液型REE形态和δ13C分布。富锰缺氧水中直接析出了锰碳酸盐和部分赤铁矿（MnS）。含锰岩石的总有机质含量（TOC，平均为 3.96%）较高，并出现黄铁矿层，这表明在锰沉积之前，硫酸盐的厌氧还原作用十分活跃，铁元素被去除。pH 值和硫化程度的增加，促进了锰矿物在水柱中的沉淀。斜坡/盆地到大陆架地区广泛的锰沉积代表了早寒武纪大范围海洋缺氧的沉积反应。这种情况有助于阐明早期生命的演化，表明在寒武纪大爆发期间，大范围的海洋缺氧可能推迟了复杂动物的辐射。

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引用次数: 0

Climate-driven peatlands development and vegetation dynamics in Northeastern China since the mid-Holocene: New evidence from Huanan peatlands 全新世中期以来中国东北地区受气候影响的泥炭地开发与植被动态：来自黄南泥炭地的新证据

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-09 DOI: 10.1016/j.palaeo.2024.112544

Yutong Qian , Dongmei Jie , Honghao Niu , Guizai Gao , Frank M. Chambers , Ziping Liu

Studying peatland evolution and vegetation patterns in response to climate change provides valuable insights into future ecosystem trends. This study focuses on the Huanan peatland located in Changbai Mountain regions in Northeast China, utilizing phytolith analysis and stable carbon isotope composition (δ¹³C) to reconstruct late Holocene vegetation dynamics. Additionally, grain size, total organic carbon (TOC), and total nitrogen (TN) analyses were conducted to understand peatland development and paleoclimate since the late Holocene. The research identifies three distinct climate periods since 5500 cal yr BP: an initial warm, humid phase (5500–4000 cal yr BP) characterized by high river levels that formed lacustrine sediments; a subsequent transition to cold, dry conditions (4000–1500 cal yr BP) that initiated peat formation; and continued dry, cold conditions (1500 cal yr BP to the present) with sustained peat growth. Phytolith data reveal a dominant forest vegetation type since 2000 cal yr BP, further divided into three periods: 2000–1300 cal yr BP, marked by diverse and dense vegetation; 1300–750 cal yr BP, with declining plant cover; and 750 cal yr BP to the present, characterized by an increase in woody plants but a reduction in local grass cover.

研究泥炭地的演化和植被模式对气候变化的响应为了解未来生态系统的发展趋势提供了宝贵的信息。本研究以位于中国东北长白山地区的黄南泥炭地为研究对象，利用植物岩石分析和稳定碳同位素组成（δ13C）重建全新世晚期的植被动态。此外，还进行了粒度、总有机碳（TOC）和总氮（TN）分析，以了解全新世晚期以来泥炭地的发展和古气候。研究确定了自公元前 5500 年以来三个不同的气候时期：最初的温暖湿润阶段（公元前 5500-4000 年），其特点是河流水位高，形成了湖沼沉积物；随后过渡到寒冷、干燥的条件（公元前 4000-1500 年），开始形成泥炭；以及持续干燥、寒冷的条件（公元前 1500 年至今），泥炭持续生长。植物岩石数据显示，自公元前 2000 年以来，森林植被类型占据主导地位，并进一步分为三个时期：公元前 2000-1300 年，植被多样且茂密；公元前 1300-750 年，植物覆盖率下降；公元前 750 年至今，木本植物增加，但当地草地覆盖率下降。

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引用次数: 0

Confirmation of Mg/Ca ratios as palaeothermometers in Atlantic limpet shells 确认镁/钙比率是大西洋帽贝的古温度计

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-09 DOI: 10.1016/j.palaeo.2024.112538

Niklas Hausmann , Donna Surge , Ivan Briz i Godino

This study provides a reassessment of magnesium to calcium (Mg/Ca) ratios in Atlantic limpet shells to determine past sea surface temperatures (SST). While Patella depressa along the Spanish shoreline and Patella caerulea in the Mediterranean have repeatedly produced reliable correlations between SST and Mg/Ca ratios, this relationship is not the case for other patelloid species. Particularly, Patella vulgata but also Nacella deaurata have been studied using Mg/Ca ratios with mixed or contrary results. In this study, we present elemental maps of these two species as well as Nacella magellanica together with oxygen isotope ratios (

δ

¹⁸O) that confirm a good relationship with SST. Our dataset also reassesses a specimen which was previously unsuccessful in providing significant correlations between

δ

¹⁸O values and Mg/Ca ratios. By reassessing these species and including modern and archaeological specimens (n = 12) from three patelloid species (P. vulgata, N. deaurata, and N. magellanica) we further add to the growing set of evidence for the reliable use of Mg/Ca ratios to detect palaeotemperature change. As a result, these species can in the future serve to determine ontogenetic age and season of capture as well as to reveal locations of interest within the growth record (i.e. annual temperature minima and maxima) for targeted

δ

¹⁸O and clumped isotope analysis.

本研究重新评估了大西洋瓣鳃纲贝壳中的镁钙（Mg/Ca）比率，以确定过去的海面温度（SST）。虽然西班牙海岸线上的消沉纹斑贝（Patella depressa）和地中海地区的钙镁纹斑贝（Patella caerulea）多次在海表温度和镁/钙比率之间建立了可靠的相关关系，但其他纹斑贝类的情况并非如此。特别是在研究蝠鲼（Patella vulgata）和 Nacella deaurata（Nacella deaurata）时，我们使用了镁/钙比率，但结果不一或相反。在本研究中，我们展示了这两个物种以及 Nacella magellanica 的元素图谱以及氧同位素比值（δ18O），证实了它们与 SST 的良好关系。我们的数据集还对一个标本进行了重新评估，该标本以前未能成功提供 δ18O 值与 Mg/Ca 比值之间的显著相关性。通过重新评估这些物种，并纳入三个蝙蝠类物种（P. vulgata、N. deaurata 和 N. magellanica）的现代和考古标本（n = 12），我们进一步增加了利用镁/钙比值检测古温度变化的可靠证据。因此，这些物种将来可用于确定个体发育年龄和捕获季节，以及揭示生长记录中感兴趣的位置（即年温度最小值和最大值），以便进行有针对性的δ18O和团块同位素分析。

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引用次数: 0

Organic carbon burial dynamics at the Chukchi Shelf margin: Implications for the Arctic Ocean carbon sink 楚科奇大陆架边缘的有机碳埋藏动力学：对北冰洋碳汇的影响

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-09 DOI: 10.1016/j.palaeo.2024.112534

Liming Ye , Xiaoguo Yu , Yanguang Liu , Anatolii S. Astakhov , Alexander Bosin , Yeping Bian , Linsen Dong , Weijia Fan , Haili Yang

Organic carbon (OC) burial plays a crucial role in regulating the Arctic Ocean's capacity to uptake atmospheric CO₂. In this study, we demonstrate the transport, deposition, and degradation patterns of different sources of OC to reveal burial dynamics at the Chukchi Shelf margin, a region with the highest primary production in the Arctic Ocean currently affected by dramatic sea ice retreat. Observations of suspended particulate material show a pronounced separation of terrestrial and marine OC in the water column, which subsequently influences OC lateral transport and differential deposition. Easily suspendable terrestrial OC is concentrated in the upper 10 m of water or sea ice and transported to the Canada Basin, where it undergoes severe degradation of fresh carbon in the water column and uppermost sediments. In contrast, faster-settling marine OC is more likely to be buried in the canyons and at the Chukchi Shelf margin, with ice algae contributing about 14 % and 55 % of OC burial in areas south and north of 73°N, respectively, leading to higher initial burial efficiency. Increasing Arctic marine primary production could thus enhance the region's role as a carbon sink over millennial timescales, although the burial efficiency of terrestrial OC will eventually exceed that of marine OC with prolonged burial time. Our findings highlight the importance of lateral transport, differential deposition, and selective degradation in Arctic carbon burial, providing a basis for objectively assessing the future capacity of the Arctic carbon sink and its feedback to climate change.

有机碳（OC）的埋藏在调节北冰洋吸收大气 CO₂ 的能力方面起着至关重要的作用。在这项研究中，我们展示了不同来源的有机碳的迁移、沉积和降解模式，以揭示楚科奇大陆架边缘的埋藏动态，该区域是北冰洋初级生产力最高的区域，目前受到海冰急剧消退的影响。对悬浮颗粒物质的观测表明，水体中的陆地和海洋有机碳明显分离，从而影响了有机碳的横向迁移和差异沉积。易于悬浮的陆地 OC 集中在水体或海冰的上层 10 米处，并被输送到加拿大盆地，在那里的水体和最上层沉积物中的新鲜碳发生严重降解。相比之下，沉降较快的海洋 OC 更有可能被埋藏在峡谷和楚科奇大陆架边缘，在北纬 73 度以南和以北地区，冰藻对 OC 埋藏的贡献率分别约为 14% 和 55%，从而提高了初始埋藏效率。因此，北极海洋初级生产力的增加可增强该地区在千年时间尺度上的碳汇作用，尽管随着埋藏时间的延长，陆地 OC 的埋藏效率最终将超过海洋 OC。我们的研究结果强调了横向迁移、差异沉积和选择性降解在北极碳埋藏中的重要性，为客观评估北极碳汇的未来能力及其对气候变化的反馈作用提供了依据。

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引用次数: 0

The collapse of the Ming Dynasty actually began with the Wanli megadrought: Insights from a hydroclimate reconstruction based on tree-ring δ18O over the past 460 years 明朝的灭亡实际上始于万历大旱：基于过去 460 年树环δ18O 的水文气候重建的启示

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-09 DOI: 10.1016/j.palaeo.2024.112548

Meng Ren , Yu Liu , Qiufang Cai , Qiang Li , Huiming Song , Changfeng Sun

Climate change has played a pivotal role in shaping Chinese history, especially during the Ming Dynasty. Previous studies have focused primarily on the Chongzhen megadrought, which is widely considered as the primary climatic perturbation behind the demise of the Ming Dynasty. However, relatively little is known about other severe drought events and their potential impact on the dynasty collapse. Additionally, the characteristics of an exceptional climatic anomaly termed the “Late Ming Weak Monsoon Period” are unclear. In this study, we reconstructed the historical variations of Palmer Drought Severity Index for July–September based on tree-ring stable oxygen isotopes (δ¹⁸O) from 1556 CE to 2015 CE in southwest Chinese Loess Plateau. Our study reveals a significant weakening of the Asian summer monsoon between 1561 CE and 1661 CE, consistent with the Late Ming Weak Monsoon Period, and unravels its structural characteristics in detail. Our reconstruction also captures a distinct humidification trend over northwest China since the early 2000s. Notably, in addition to the well-known Chongzhen megadrought, our study records the severe Wanli megdrought (1585–1590 CE) during the late Ming Dynasty, an event that rarely featured in earlier studies, exhibiting comparable duration and severity to the Chongzhen megadrought. Further analysis indicates that Wanli megadrought may have served as an early trigger for the collapse of the Ming Dynasty. Furthermore, our analysis implicates the El Niño–Southern Oscillation as a contributing factor in both the Wanli and Chongzhen megadroughts, and thus to the ultimate collapse of the Ming Dynasty by affecting the Asian summer monsoon intensity.

气候变化在塑造中国历史，尤其是明朝历史的过程中发挥了举足轻重的作用。以往的研究主要集中在崇祯大旱上，人们普遍认为这是明朝灭亡背后的主要气候扰动。然而，人们对其他严重干旱事件及其对明朝灭亡的潜在影响知之甚少。此外，被称为 "晚明弱季风期 "的特殊气候异常的特征也不清楚。在本研究中，我们基于树环稳定氧同位素（δ18O）重建了中国西南黄土高原公元1556年至2015年7-9月帕尔默干旱严重程度指数的历史变化。我们的研究揭示了公元 1561 年至公元 1661 年间亚洲夏季季风的显著减弱，这与晚明弱季风期一致，并详细揭示了其结构特征。我们的重建还捕捉到了自 21 世纪初以来中国西北地区明显的潮湿化趋势。值得注意的是，除了众所周知的崇祯特大干旱外，我们的研究还记录了明朝晚期严重的万历特大干旱（公元 1585-1590 年），这一事件在早期研究中很少出现，其持续时间和严重程度与崇祯特大干旱相当。进一步的分析表明，万历大旱可能是明朝灭亡的早期导火索。此外，我们的分析表明，厄尔尼诺-南方涛动是万历大旱和崇祯大旱的诱因，并通过影响亚洲夏季季风强度最终导致明朝灭亡。

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引用次数: 0

Melanoides tuberculata and Zootecus insularis gastropod shells provide a snapshot into past hydroclimatic conditions of arid environments: New perspectives from Oman Melanoides tuberculata 和 Zootecus insularis 腹足类贝壳提供了干旱环境过去水文气候条件的缩影：来自阿曼的新视角

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-08 DOI: 10.1016/j.palaeo.2024.112542

Katharina E. Schmitt , Tara Beuzen-Waller , Conrad Schmidt , Lucas Proctor , Susanne Lindauer , Christoph J. Gey , Dana Pietsch , Bernd R. Schöne

Shells of the aquatic gastropod Melanoides tuberculata and the terrestrial gastropod Zootecus insularis were analysed using high-resolution isotope sampling (up to 274 samples per shell) to assess their potential use as a proxy for hydroclimatic and palaeoenvironmental reconstruction in drylands. A total of 169 snails (fossil and modern) were collected from 37 sites in Northern Oman and Dhofar, with each site selected for its specific geomorphological, archaeological or ecological context. This included fluvial terraces, playa environments, modern oasis gardens, irrigation channels and archaeological sites from the Neolithic (6,000–3,200 BCE) and Early Bronze Age (3,200–2,000 BCE) periods. The δ¹⁸O data obtained from these gastropods could be classified into eight different patterns, three for the aquatic snails (Type 1 A–C) and five for the terrestrial snails (Type 2 A–E), which were linked to the environmental context of their habitat. Furthermore, the use of the aquatic snails enabled us to distinguish between groundwater and surface water signals, whereas the terrestrial snails were employed to reconstruct changes in rainfall origin, humidity, evaporation, regular wet-dry cycles, and meteorological events. According to the results, gastropods can be used to elucidate the long-term, local evolution of rain-fed floodplain ecosystems in drylands and to identify the hydrological resources present in the vicinity of archaeological sites, particularly with regard to type 1 A-C (e.g., surface water vs groundwater).

利用高分辨率同位素取样（每个贝壳多达 274 个样本）对水生腹足类 Melanoides tuberculata 和陆生腹足类 Zootecus insularis 的贝壳进行了分析，以评估它们作为旱地水文气候和古环境重建替代物的潜在用途。从阿曼北部和佐法尔的 37 个地点共采集了 169 只蜗牛（化石和现代蜗牛），每个地点都是根据其特定的地貌、考古或生态环境而选择的。其中包括新石器时代（公元前 6,000-3,200 年）和青铜时代早期（公元前 3,200-2,000 年）的河流阶地、洼地环境、现代绿洲花园、灌溉渠道和考古遗址。从这些腹足类动物身上获得的δ18O数据可分为八种不同的模式，其中三种为水生蜗牛模式（类型 1 A-C），五种为陆生蜗牛模式（类型 2 A-E），这些模式与其栖息地的环境背景有关。此外，利用水生蜗牛可以区分地下水和地表水信号，而利用陆生蜗牛则可以重建降雨来源、湿度、蒸发、干湿周期和气象事件的变化。根据研究结果，腹足类动物可用于阐明干旱地区雨水灌溉的洪泛平原生态系统的长期、局部演变，并确定考古遗址附近的水文资源，特别是 1 A-C 类（如地表水与地下水）。

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引用次数: 0

Microbial mediated hardening of a Central Mediterranean upper shelf seafloor during the MIS 5.5; a possible post global warming scenario? MIS5.5时期微生物介导的地中海中部上陆架海底硬化；全球变暖后的可能情景？

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-05 DOI: 10.1016/j.palaeo.2024.112539

Edoardo Perri, Pierluigi Santagati, Mario Borrelli, Salvatore Guerrieri

Higher sea level and sea surface temperature than at present have been inferred for the Last Interglacial (MIS 5.5, 135–116 ka), making it a good analogue for modeling the climate response of the environment to global warming in the near future. With the aim of predicting the possible evolution of some central Mediterranean shallow sandy seabeds, a MIS 5.5 biocalcarenite was investigated (Gulf of Taranto, Italy). Limited post-depositional diagenesis affected this deposit, which represents an infralittoral sandy seabed, with local vegetation and relatively high energy conditions. Medium-coarse sand sized bioclasts, with a negligible quantity of siliciclastic, compose the sediment that also hosts large shells of mollusks. Micritic cements are widespread, often in continuum with the micritized part of the shells, showing non-isopachous aphanitic and filamentous rims, aphanitic micro-mounds, vacuolar peloidal menisci, and aphanitic pore-filling matrix. All these cements consist of submicrometer anhedral or nanospheroidal crystals of low-Mg calcite, mixed with a smaller amount of irregular plate-like crystals of saponite. Micritic cements are also rich in mineralized filamentous, tubular, and subspherical bacterial bodies. This highlights the occurrence of an epilithic and endolithic microbial community forming a biofilm that stabilized the mobile sediment as consequence of the microbial mediated early cement precipitation. This led the synsedimentary hardening of some parts the mobile sandy substrate, the settlement of sessile taxa - such as Spondylus gaederopus, oysters, serpulids and barnacles, together with endofaunal organisms. Early micritic cementation is common in modern tropical climate, whereas is substantially absent in the modern Mediterranean. Consequently, its presence in the MIS 5.5 deposit confirms warmer sea water temperature compared to today (estimated at ca +2 °C) and suggests that similar hardening of mobile substrates may occur in the near future as a response to global warming.

据推断，末次间冰期（MIS 5.5，135-116 ka）的海平面和海面温度都比现在高，因此是模拟不久的将来环境对全球变暖的气候反应的一个很好的模拟对象。为了预测地中海中部一些浅沙质海床可能发生的演变，研究人员对 MIS 5.5 生物钙钛矿（意大利塔兰托湾）进行了调查。沉积后成岩作用对该沉积物的影响有限，该沉积物代表了滨海下砂质海床，当地有植被，能量条件相对较高。沉积物由中粗砂大小的生物碎屑组成，硅质碎屑的数量微乎其微，沉积物中还有大量的软体动物贝壳。微晶胶结物很普遍，通常与贝壳的微晶部分连成一体，显示出非异型的闪长岩和丝状边缘、闪长岩微丘、空泡状球状半月板和闪长岩孔隙填充基质。所有这些胶结物都是由亚微米的低镁方解石的正方体或纳米球状晶体与少量不规则的皂石板状晶体混合组成。微晶胶结物还富含矿化丝状、管状和亚球状细菌体。这突出表明，在微生物介导的早期胶结沉淀作用下，形成生物膜的表生和内生微生物群落稳定了流动沉积物。这导致移动沙质基质的某些部分发生了合成沉积硬化，无梗类群（如脊柱藻、牡蛎、蛇舌藻和藤壶）以及内生生物在此定居。早期微砂胶结在现代热带气候中很常见，但在现代地中海地区却很少见。因此，在 MIS 5.5 沉积物中出现这种现象证明海水温度比现在更高（估计约为 +2°C），并表明在不久的将来可能会出现类似的移动基质硬化现象，以应对全球变暖。

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引用次数: 0

Late Pleistocene to early Holocene vegetation and environmental changes in the tropical Leizhou Peninsula, South China: New evidence from the n-alkane record 华南热带雷州半岛晚更新世至全新世早期的植被与环境变化：来自正构烷烃记录的新证据

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-05 DOI: 10.1016/j.palaeo.2024.112541

Jia Huo, Jibin Xue, Jingqiang Chen, Yanting Li, Mingyi Chen, Zhenzhen Zhao, Yuxin Liu

Understanding past long-term vegetation responses to regional or even global climate change and forcing mechanisms is essential to future climate change projections. However, due to the lack of long-term terrestrial sedimentary records, there are few studies focusing on vegetation changes in tropical southern China since the last glacial period, especially from the perspective of peat n-alkane records. Here, we have presented a peat core record from the Xialu peatland in the northern Leizhou Peninsula, and n-alkanes were investigated in conjunction with multiple proxy indicators. Our results showed that the organic matter sources were mainly a mixture of aquatic and terrestrial vegetation, with terrestrial vegetation accounting for most of the bulk organic matter composition. From ∼44.1 to 29 cal kyr BP, the organic matter source was mainly dominated by terrestrial vegetation, which corresponds to warm and humid conditions. From 29 to 14 cal kyr BP, the input of the terrestrial vegetation was reduced, the aquatic vegetation input increased, implying cool and dry conditions. From 14 to 9.3 cal kyr BP, the climate gradually became warmer and wetter, and terrestrial vegetation dominated in this area. Overall, the climatic conditions from the Xialu peatland were generally consistent with other records from adjacent areas. Our results suggest that, during the Last Glacial Maximum (LGM), a substantial drop in regional and global sea levels may have been the main cause of drought in tropical southern China on orbital timescales. Meanwhile, several climatic fluctuations on millennial timescales could have been influenced by the variability of the North Atlantic Meridional Overturning Circulation (AMOC) and migration of the Intertropical Convergence Zone (ITCZ).

了解过去植被对区域甚至全球气候变化的长期响应和强迫机制对未来气候变化预测至关重要。然而，由于缺乏长期陆相沉积记录，关注上一个冰川期以来华南热带地区植被变化的研究很少，特别是从泥炭正构烷烃记录的角度。在此，我们展示了雷州半岛北部下陆泥炭地的泥炭岩芯记录，并结合多种代用指标对正构烷烃进行了研究。结果表明，有机质来源主要是水生植被和陆生植被的混合，其中陆生植被占有机质组成的绝大部分。从 44.1 至 29 cal kyr BP，有机质来源主要以陆生植被为主，这与温暖潮湿的条件相吻合。从 29 至 14 cal kyr BP，陆生植被的输入减少，水生植被的输入增加，这意味着凉爽和干燥的条件。从 14 至 9.3 cal kyr BP，气候逐渐变得温暖湿润，陆生植被在这一地区占主导地位。总体而言，下陆泥炭地的气候条件与邻近地区的其他记录基本一致。我们的研究结果表明，在末次冰川极盛时期（LGM），区域和全球海平面的大幅下降可能是造成华南热带地区轨道时间尺度上干旱的主要原因。同时，一些千年时间尺度上的气候波动可能受到北大西洋经向翻转环流（AMOC）的变化和热带辐合带（ITCZ）迁移的影响。

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引用次数: 0

From paleolake to peatland: Paleo environmental changes over glacial and interglacial cycles (Mid-Pleistocene) in the Colônia Basin, Brazil 从古湖泊到泥炭地：巴西科洛尼亚盆地冰川和间冰期周期（中更新世）的古环境变化

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-05 DOI: 10.1016/j.palaeo.2024.112528

Gisele C. Marquardt , Denise C. Bicudo , Jaques E. Zanon , Carlos E.M. Bicudo , Ingrid Horák-Terra , Marie-Pierre Ledru

Diatom and geochemical elements were used to analyze the transition from lake to peatland in the Colônia basin, São Paulo, Brazil; local versus regional driving factors were examined. Sediment core COL17–1, section 1470–800 cm depth shows five distinct diatom intervals offering insights into environmental changes and ecological characteristics based on sediment sources, diatom productivity, and bog wetness. Colônia basin evolution exhibited a progressive transition from mineral elements, associated with catchment instability during the lake stage, to higher levels of organic-rich sediments towards the uppermost section of the core. This shift was accompanied by the increasing presence of elements reflecting redox/productivity dynamics under changing conditions. Simultaneously, Br concentrations increased during peat formation indicating alterations in organic matter were influenced by atmospheric circulation and precipitation. During the transition from lake to peatland, the paleolake shallowing process showed successive colonization by benthic acidophilus diatom taxa, indicating a broader littoral zone and subsequent disappearance of diatoms under dry conditions. After a benthic stage, the diatom content shifted to one of planktonic dominance characterized by Aulacoseira sp., marking the return to cold-wet conditions and a moderately deep, flooded environment. Subsequently, the basin evolved into a completely flooded, turbulent peatland dominated by the Aulacoseira granulata complex. An uppermost layer sterile in diatom was associated with warmer and drier conditions and decrease in the concentration of mineral elements. Present results compared with core CO14 and Lake Titicaca showed benthic-rich levels during the penultimate glacial period and low benthic abundances. This differed the glacial-interglacial transition from those of COL17–1, which was dominated by planktonic-rich levels, suggesting the need for either a reassessment of our age model or the influence of local factors on diatom content. These findings highlight the sensitivity of diatoms to climate shifts, particularly in tropical regions, across different glacial-interglacial cycles.

利用硅藻和地球化学元素分析了巴西圣保罗科洛尼亚盆地从湖泊向泥炭地的过渡；研究了当地和区域的驱动因素。沉积物岩芯 COL17-1，1470-800 厘米深的部分显示了五个不同的硅藻区间，根据沉积物来源、硅藻生产力和沼泽湿度，深入分析了环境变化和生态特征。科洛尼亚盆地的演化呈现出从与湖泊阶段集水区不稳定性有关的矿物元素向岩心最上部富含有机质沉积物过渡的渐进过程。伴随着这一转变，反映条件变化下氧化还原/生产力动态的元素也越来越多。同时，在泥炭形成过程中，Br 的浓度增加，表明有机质的变化受到大气环流和降水的影响。在从湖泊向泥炭地过渡的过程中，古湖泊的浅化过程显示出底栖嗜酸硅藻类群的连续定殖，这表明在干燥条件下，湖岸带更宽，硅藻随之消失。在经历了底栖阶段后，硅藻含量转为以 Aulacoseira sp.为特征的浮游生物占主导地位，这标志着冷湿条件和中等深度的洪水环境的恢复。随后，盆地演变成完全淹没的湍流泥炭地，以 Aulacoseira granulata 复合体为主。最上层硅藻不育与较温暖干燥的环境和矿物元素浓度下降有关。与 CO14 号岩心和的的喀喀湖的比较结果表明，在倒数第二个冰川期，底栖生物丰富，但底栖生物丰度较低。这与 COL17-1 的冰川-间冰期过渡不同，COL17-1 以富含浮游生物为主，这表明需要重新评估我们的年龄模型或当地因素对硅藻含量的影响。这些发现凸显了硅藻在不同冰川-间冰期周期对气候变迁的敏感性，尤其是在热带地区。

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引用次数: 0

Sedimentary record of primary productivity changes in a crater lake in Northeast China since the Last Glacial Maximum 末次冰川极盛时期以来中国东北一个火山口湖初级生产力变化的沉积记录

IF 2.6 2区地球科学 Q2 GEOGRAPHY, PHYSICAL

Palaeogeography, Palaeoclimatology, Palaeoecology

Pub Date : 2024-10-05 DOI: 10.1016/j.palaeo.2024.112543

Yao Wang , Weiwei Sun , Enlou Zhang , Enfeng Liu , Xianqiang Meng , Zhenyu Ni , Wenfang Zhang

High-resolution primary productivity records are valuable for identifying lacustrine ecosystem degradation in the context of long-term climatic variability. In this paper, we analyse primary productivity changes in a seasonally ice-covered crater lake (Lake Tuofengling) in northeast China since the Last Glacial Maximum using biogenic silica content and the carbon preference index of short-chain n-alkanes as proxies. Results show that primary productivity was lower during the cold and dry glacial period, whereas it was higher during the warm and humid Holocene. During the last deglaciation, primary productivity experienced a ∼ 1.5-kyr lagged response to Bølling-Allerød warming, and multiple oscillations during the Younger Dryas. Additionally, the peak productivity of the entire profile also occurred during this period. These fluctuations and the highest primary productivity are suggested to be the result of the combined influences of increased summer temperatures and regional permafrost melting. The current state of primary productivity in Lake Tuofengling is moderate but has been increasing since the abrupt increase in diatom productivity after ∼3 ka B.P. This stage is associated with increased dust deposition and longer ice-free periods under winter-warming conditions. We suggest that longer seasonal stratification under the current warmer winters and increased nutrient concentrations caused by decreased lake level will increase the risk of lake ecosystem degradation in the future.

高分辨率的初级生产力记录对于确定长期气候变异背景下的湖泊生态系统退化非常有价值。本文采用生物硅含量和短链正构烷烃的碳偏好指数作为代用指标，分析了中国东北一个季节性冰盖火山口湖（坨峰岭湖）自末次冰川极盛时期以来的初级生产力变化。结果表明，在寒冷干燥的冰川期，初级生产力较低，而在温暖潮湿的全新世，初级生产力较高。在上一次冰川期，初级生产力对博林-阿勒勒德变暖的反应滞后了 1.5 千年，在少干期则出现了多次振荡。此外，整个剖面的生产力峰值也出现在这一时期。这些波动和最高初级生产力被认为是夏季气温升高和区域永久冻土融化共同影响的结果。目前，拓风岭湖的初级生产力处于中等水平，但自硅藻生产力在公元前 3 ka 年以后突然上升以来，初级生产力一直在上升。我们认为，在目前冬季变暖的条件下，季节性分层时间延长，湖泊水位下降导致营养物质浓度增加，这将增加未来湖泊生态系统退化的风险。

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引用次数: 0