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The paleolandscape of Melka Kunture (Ethiopia) at the time of the earliest human peopling Melka Kunture(埃塞俄比亚)的古景观,在最早的人类居住的时候
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-23 DOI: 10.1016/j.palaeo.2025.113520
Rita T. Melis , Margherita Mussi
The archeological site-complex of Melka Kunture, at 2000 m asl on the west side of the Main Ethiopian Rift, lies in a half-graben crossed by the upper Awash River. Sedimentation processes led to the building up of stratigraphic sequences consisting of primary volcaniclastic deposits interbedded with reworked volcaniclastics emplaced in a floodplain environment. We describe here the changing paleolandscape and the implications on hominin peopling from 2,000,000 to 600,000 years ago, using the sequence of the thoroughly investigated Gombore gully with added information from other sites of Melka Kunture. Together with archaeology and paleontology, detailed information is provided by stratigraphic sections, pollen and stable isotope analysis and by the ichnological record.
The available data show a fluvial dynamic landscape characterized by a floodplain with a meandering river, gravel lag deposits and fine-grained overbank deposits. The vegetation was of Afromontane type. A major volcano-tectonic event at 1.2 Ma blanketed the area with products which clogged the valley before the river was eventually able to resume its course. The abundant artefacts and faunal remains in the gravel deposits suggest that during the Early Pleistocene and the early Middle Pleistocene, before and after the 1.2 Ma event both Homo erectus with Oldowan and then Acheulean lithic productions, and later on H. heidelbergensis with middle Acheulean ones, repeatedly came to those well-drained spots. Single-purpose sites also exist in different environments and other ones provide evidence of hominins roaming through the plain.
Melka Kunture考古遗址群位于海拔2000米的埃塞俄比亚主裂谷西侧,位于阿瓦什河上游穿过的半地堑中。沉积作用形成了由原始火山碎屑沉积物与沉积在洪泛平原环境中的再加工火山碎屑互层组成的层序。我们在这里描述了从200万到60万年前变化的古地貌及其对人类居住的影响,使用了彻底调查的贡博尔沟序列和梅尔卡文化其他遗址的附加信息。与考古学和古生物学一起,地层剖面、花粉和稳定同位素分析以及技术记录提供了详细的信息。现有资料显示了一个河流动力学景观,其特征是河漫滩有蜿蜒的河流,砾石滞后沉积和细粒河岸沉积。植被类型为非洲山地型。1.2 Ma的一次主要火山构造事件使该地区被产品覆盖,在河流最终能够恢复其路线之前堵塞了山谷。砾石沉积物中丰富的人工制品和动物遗骸表明,在早更新世和中更新世早期,即1.2 Ma事件前后,直立人与奥尔多瓦石器和阿舍利石器的生产,以及后来的海德堡人与阿舍利石器的生产,都曾多次来到这些排水区。单一用途的遗址也存在于不同的环境中,还有一些遗址提供了人类在平原上漫游的证据。
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引用次数: 0
Spatial-temporal carbon isotope changes during the late Wuchiapingian to Early Triassic in South China and their global environmental implications 华南五家坪世晚期至早三叠世碳同位素时空变化及其全球环境意义
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-23 DOI: 10.1016/j.palaeo.2025.113523
Yawen Cui , Menghan Li , Lilin Sun , Dandan Li , Guijie Zhang , Xiaolin Zhang , Yanan Shen
Pronounced perturbations to the global carbon cycle from the Late Permian to the Early Triassic are recorded as several large C-isotope excursions. However, the overall significance of these perturbations, as well as their environmental implications and biotic responses, remains to be better constrained. Here, we present high-resolution C-isotopic data of carbonate (δ13Ccarb) spanning the late Wuchiapingian to Early Triassic from the Jiangya and Chongyang sections, deposited along the northern margin of the middle Yangtze Platform. The C-isotope records show prominent δ13Ccarb excursions both near the Wuchiapingian-Changhsingian boundary (WCB) and end-Permian mass extinction (EPME), which can be correlated at regional to global scales. Sedimentological and geochemical observations suggest that enhanced remineralization of upwelled 12C-enriched dissolved organic carbon (DOC), driven by the incursion of anoxic/euxinic deep waters, likely contributed to the negative δ13Ccarb excursions observed near the WCB and EPME. Oxidative decay of this upwelled DOC would have consumed key oxidants, including oxygen and sulfate, thereby promoting the expansion of marine anoxic/euxinic conditions. A pronounced depth gradient in δ13Ccarb between coeval shallow- and deep-water settings further supports this mechanism and links the negative excursions to widespread anoxia/euxinia in the eastern Paleo-Tethys Ocean. Together, our data support that the expansion of oceanic anoxia/euxinia may have played a crucial role in driving the biotic crises associated with the WCB and EPME.
从晚二叠世到早三叠世,全球碳循环的明显扰动被记录为几次大的c同位素偏移。然而,这些扰动的总体意义,以及它们的环境影响和生物反应,仍然需要更好地加以限制。本文研究了中扬子地台北缘江崖段和重阳段五家坪世晚期至早三叠世碳酸盐岩的高分辨率碳同位素(δ13Ccarb)。在五家坪-长兴界线(WCB)和二叠纪末大灭绝(EPME)附近,c同位素记录显示出明显的δ13Ccarb偏移,具有区域性和全球性的相关性。沉积学和地球化学观测表明,缺氧/富氧深水的侵入可能导致上涌富12c溶解有机碳(DOC)的再矿化作用增强,这可能是WCB和EPME附近δ13Ccarb负偏移的原因。上升流DOC的氧化衰变消耗了关键的氧化剂,包括氧和硫酸盐,从而促进了海洋缺氧/缺氧条件的扩大。在同时期的浅水和深水环境中,δ13Ccarb的显著深度梯度进一步支持了这一机制,并将负偏移与古特提斯洋东部广泛的缺氧/缺氧联系起来。总之,我们的数据支持海洋缺氧/缺氧的扩张可能在推动与WCB和EPME相关的生物危机中发挥了至关重要的作用。
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引用次数: 0
Magnetic chronology of the late Miocene Wulangou red clay sequences in the northern Otindag Sandy Land 敖廷达沙地北部晚中新世乌兰沟红粘土层序的磁年代学
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-23 DOI: 10.1016/j.palaeo.2025.113521
Hongyu Qi , Yali Zhou , Jiangli Pang , Xiaoke Qiang , Jiale Wang , Baofeng Ma , Tong Feng , Xichen Li , Yiting Zhao , Yingying Cui , Liping Jiang , Siying Yue
<div><div>Asian environment is characterized by the uplift of the Tibetan Plateau, the formation of the Asian monsoon, and inland aridification during Cenozoic. However, there are significant controversies regarding the evolutionary patterns of the Asian monsoon and the historical records of inland aridification documented by different carriers in different regions. The Otindag Sandy Land, one of the inland arid and semi-arid regions in northwestern China, is situated along the northern limit of the East Asian Summer Monsoon (EASM)—a boundary of the East Asian monsoon area—and is highly sensitive to climate change. Owing to extensive Cenozoic aeolian deposits developed in the area, it serves as an ideal region for studying past climate and environmental changes. Previous research on the chronology of sandy land has primarily focused on the Quaternary, with limited attention paid to the stratigraphic age of Neogene aeolian sediments, largely due to the absence of suitable geological markers. This study examined the basalt-lacustrine sand-aeolian red clay sedimentary sequence of the Wulangou section in the northern Otindag Sandy Land. Paleomagnetism was used to determine the magnetostratigraphy of the aeolian red clay, and the <sup>40</sup>Ar/<sup>39</sup>Ar isotope dating method was employed to obtain the absolute age of the basalt. Combined with stratigraphic correlations from the Baogeda Ula section, which is a standard stratigraphic section within the study area, and biostratigraphic ages of the Baodean Period, the ages of the lacustrine sand layers in the region were determined. This study established a complete chronological framework for the stratigraphic sedimentary sequence of the Wulangou section. Climate and environmental changes were analyzed based on the sedimentary characteristics, magnetic susceptibility, and grain size of the strata. The research results indicated that the red clay magnetic stratum captured the geomagnetic polarity sequence from C5n.2n to C4n.2n, spanning approximately 11.04–8.06 Ma. The ages of the three aeolian sand layers interbedded in the lower part of the red clay were 11.04–10.91 Ma, 10.51–10.44 Ma, and 10.37–10.23 Ma, respectively. Since the late Miocene, the climate of the northern Otindag Sandy Land has been predominantly cold and dry, undergoing a fluctuation that transitions from cold and dry, then shifts to warm and wet, and ultimately reverts back to cold and dry. From 11.04 to 10.02 Ma, red clay and aeolian sand interbedding developed, characterized by low magnetic susceptibility, coarser particles, and a relatively cold and dry climate with strong aeolian sand activity. Between 10.02 and 8.91 Ma, the magnetic susceptibility reached a high value stage with a finer grain size and relatively warm and humid climate. The weak and strong pedogenic layers in red clay were alternately developed. During 8.91–8.06 Ma, the red clay exhibited lower magnetic susceptibility and coarser grain size, with thick calca
亚洲环境以新生代青藏高原隆升、亚洲季风形成和内陆干旱化为特征。然而,对于亚洲季风的演化模式和不同地区不同载体所记录的内陆干旱化历史记录,存在较大的争议。浑天达克沙地是中国西北内陆干旱半干旱区之一,位于东亚夏季风(EASM)北端,是东亚季风区的边界,对气候变化非常敏感。由于该区广泛发育新生代风成沉积,是研究过去气候和环境变化的理想区域。以往对沙地年代学的研究主要集中在第四纪,对新近纪风成沉积地层年龄的研究较少,主要原因是缺乏合适的地质标志。本文研究了敖廷达沙地北部乌兰沟剖面玄武岩—湖相砂—风成红粘土沉积序列。采用古地磁法确定了风成红粘土的磁地层,采用40Ar/39Ar同位素定年法确定了玄武岩的绝对年龄。结合研究区标准地层剖面宝格达乌拉剖面的地层对比和宝丁期生物地层年龄,确定了该地区湖相砂层的年龄。建立了乌兰沟剖面地层沉积序的完整年代学格架。根据沉积特征、磁化率和地层粒度分析了气候环境变化。研究结果表明,红粘土磁性地层捕获了C5n以来的地磁极性序列。2n到C4n。2n,跨度约11.04-8.06 Ma。红粘土下部互层的3个风成砂层年龄分别为11.04 ~ 10.91 Ma、10.51 ~ 10.44 Ma和10.37 ~ 10.23 Ma。中新世晚期以来,浑善达克沙地北部气候以寒冷干燥为主,经历了从寒冷干燥到温暖潮湿,最后又回到寒冷干燥的波动。11.04 ~ 10.02 Ma,红粘土与风沙互层发育,磁化率低,颗粒粗,气候相对寒冷干燥,风沙活动强烈。在10.02 ~ 8.91 Ma之间,磁化率达到高值阶段,晶粒尺寸较细,气候相对温暖湿润。红粘土弱成土层与强成土层交替发育。8.91 ~ 8.06 Ma期间,红粘土磁化率较低,粒度较粗,通过淋滤和降水形成较厚的钙质板层,其风化过程相当于第四纪黄土的脱钾富钙过程,表明气候相对寒冷干燥。红粘土中存在风成砂层,表明该地区早在11.04 Ma时就存在活跃的风成砂过程。晚中新世以来,在青藏高原隆升、全球冰量变化和区域侵蚀加剧的驱动下,浑浑达克沙地北部的气候演变与东亚季风变化密切相关,构成了全球气候变冷和变干背景下亚洲内陆干旱加剧的明显区域响应。
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引用次数: 0
Late Miocene tectonic reorganization and regional development of thrust faulting in the northeastern Tibetan Plateau 青藏高原东北部晚中新世构造重组与逆冲断裂区域发育
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-23 DOI: 10.1016/j.palaeo.2025.113522
Hao Xie , Caicai Liu , Dewen Zheng , Ying Wang , Jingxing Yu , Xudong Zhao , Zhuqi Zhang , Li Deng , Jiawei Zhang , Huiping Zhang
Constraining the initiation of intracontinental thrust faults is crucial for understanding deformation sequences that occurred during the growth of the Tibetan Plateau. This study investigates the activation timing of the nearly E–W-trending Qinghainan Shan and Gonghenan Shan thrust faults through integrated provenance analyses of Cenozoic sediments from the Chaka–Gonghe Basin, including sandstone petrography, heavy mineral assemblages, and detrital zircon U-Pb geochronology. Results reveal a pronounced provenance shift at ∼6–7 Ma, marked by a sharp increase in sediment derived from the adjacent Qinghainan Shan and Gonghenan Shan. This transition coincides with a decline in mineral maturity indices along with a change in the rotational trend, reflecting mountain uplift and constraining the initiation of these thrust faults to the late Miocene. Regionally, deformation propagated sequentially from WNW-trending strike-slip boundary faults to NNW-trending dextral strike-slip fault systems, and subsequently to intrablock thrusts. The late Miocene onset of these thrust faults represents a key kinematic step in strain partitioning, accommodating crustal shortening during the India–Asia convergence and facilitating the northeastward growth of the plateau. This progression from boundary faulting to distributed interior deformation supports a model of continuous, rather than rigid-block tectonic deformation during continental convergence.
控制陆内逆冲断层的起爆对于理解青藏高原发育过程中的变形序列至关重要。本文通过对察卡—共和盆地新生代沉积物源的综合分析,包括砂岩岩相学、重矿物组合、碎屑锆石U-Pb年代学等,探讨了近东西向的青海南山和公河南山逆冲断裂的活化时间。结果显示,在~ 6 ~ 7 Ma期间,物源发生了明显的转移,其特征是来自邻近的青海南山和公河南山的沉积物急剧增加。这一转变与矿物成熟度指数的下降和旋转趋势的变化相吻合,反映了山体隆升,将这些逆冲断层的起生限制在晚中新世。从区域上看,变形从西西向走滑边界断裂依次传播到北西向右走滑断裂系统,然后传播到块内逆冲构造。这些逆冲断层的晚中新世起生代表了应变划分的关键运动步骤,适应了印度-亚洲辐合期间地壳的缩短,促进了高原的东北生长。这种从边界断裂到分布的内部变形的进展支持了大陆收敛期间连续而非刚性块构造变形的模型。
{"title":"Late Miocene tectonic reorganization and regional development of thrust faulting in the northeastern Tibetan Plateau","authors":"Hao Xie ,&nbsp;Caicai Liu ,&nbsp;Dewen Zheng ,&nbsp;Ying Wang ,&nbsp;Jingxing Yu ,&nbsp;Xudong Zhao ,&nbsp;Zhuqi Zhang ,&nbsp;Li Deng ,&nbsp;Jiawei Zhang ,&nbsp;Huiping Zhang","doi":"10.1016/j.palaeo.2025.113522","DOIUrl":"10.1016/j.palaeo.2025.113522","url":null,"abstract":"<div><div>Constraining the initiation of intracontinental thrust faults is crucial for understanding deformation sequences that occurred during the growth of the Tibetan Plateau. This study investigates the activation timing of the nearly E–W-trending Qinghainan Shan and Gonghenan Shan thrust faults through integrated provenance analyses of Cenozoic sediments from the Chaka–Gonghe Basin, including sandstone petrography, heavy mineral assemblages, and detrital zircon U-Pb geochronology. Results reveal a pronounced provenance shift at ∼6–7 Ma, marked by a sharp increase in sediment derived from the adjacent Qinghainan Shan and Gonghenan Shan. This transition coincides with a decline in mineral maturity indices along with a change in the rotational trend, reflecting mountain uplift and constraining the initiation of these thrust faults to the late Miocene. Regionally, deformation propagated sequentially from WNW-trending strike-slip boundary faults to NNW-trending dextral strike-slip fault systems, and subsequently to intrablock thrusts. The late Miocene onset of these thrust faults represents a key kinematic step in strain partitioning, accommodating crustal shortening during the India–Asia convergence and facilitating the northeastward growth of the plateau. This progression from boundary faulting to distributed interior deformation supports a model of continuous, rather than rigid-block tectonic deformation during continental convergence.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"684 ","pages":"Article 113522"},"PeriodicalIF":2.7,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145842089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Factors affecting 87Sr/86Sr preservation in conodont apatite: An example from the Ordovician of Baltoscandia 影响牙形石磷灰石87Sr/86Sr保存的因素——以巴尔托斯坎迪亚奥陶系为例
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-22 DOI: 10.1016/j.palaeo.2025.113524
Christopher T. Conwell , Matthew R. Saltzman , Anders Lindskog , Mats E. Eriksson , Elizabeth M. Griffith , Stephen A. Leslie , Cole T. Edwards , Olle Hints , Achim D. Herrmann
Despite frequent use of conodonts as an archive for seawater 87Sr/86Sr, available diagenetic screening tools are inconsistent predictors of primary seawater 87Sr/86Sr preservation. Here, we attempt to isolate variables affecting the preservation of seawater 87Sr/86Sr in conodonts. We present new Middle–Late Ordovician (∼470–450 Ma) conodont 87Sr/86Sr from mid-paleolatitude (30–45°S) carbonate successions from central Sweden (Fjäcka, Kårgärde) and Estonia (Uuga Cliff, Viki borehole) which have low Conodont Alteration Index (CAI) values of 1–1.5. Coeval 87Sr/86Sr measurements from Kårgärde and Estonian sections are offset from global seawater by ∼ +2 × 10−4 but preserve the overall structure of the seawater curve, suggesting minor diagenetic Sr exchange. 87Sr/86Sr measurements from the more argillaceous Fjäcka section show extensive alteration with highly radiogenic values as much as ∼6 × 10−4 greater than global seawater and a stratigraphic trend that diverges from the seawater curve. This may be explained by highly radiogenic Sr contribution from the Kinnekulle K-bentonite and Fjäcka shale units that occur at Fjäcka section.
We compiled 1164 conodont 87Sr/86Sr measurements spanning ∼485–250 Ma and categorized measurements by host rock, sample preparation, paleolatitude, and CAI. Boxplots and Mann-Whitney U testing of residual values relative to the seawater curve (87Sr/86Srconodont87Sr/86Srseawater) reveal that paleolatitude and associated differences in sedimentation rate affect preservation of seawater 87Sr/86Sr values in conodonts. The relative abundance of clay minerals did not significantly correlate with residual values for conodonts from mid- or low-latitude deposits. We recommend that future investigations of seawater 87Sr/86Sr records using conodont apatite target low-latitude settings with high sedimentation rate and CAI ≤ 2.
尽管牙形刺经常被用作海水87Sr/86Sr的存档,但现有的成岩筛选工具对原生海水87Sr/86Sr保存的预测并不一致。在这里,我们试图分离影响海水87Sr/86Sr在牙形刺中保存的变量。我们在瑞典中部(Fjäcka, Kårgärde)和爱沙尼亚(Uuga Cliff, Viki钻孔)的中古纬度(30-45°S)碳酸盐岩地层中发现了新的中晚奥陶世(~ 470-450 Ma)牙形石87Sr/86Sr,牙形石蚀变指数(CAI)值较低,为1-1.5。Kårgärde和爱沙尼亚剖面的同期87Sr/86Sr测量值与全球海水偏移了~ +2 × 10−4,但保留了海水曲线的整体结构,表明存在轻微的成岩Sr交换。较泥质Fjäcka剖面的87Sr/86Sr测量显示广泛的蚀变,高放射性成因值比全球海水高~ 6 × 10−4,地层趋势偏离海水曲线。这可能是由于Fjäcka剖面的Kinnekulle k -膨润土和Fjäcka页岩单元对Sr的高放射性贡献所致。我们收集了1164个牙形石87Sr/86Sr测量值,跨度为485-250 Ma,并根据宿主岩石、样品制备、古纬度和CAI对测量值进行了分类。箱形图和相对于海水曲线(87Sr/ 86srconodon - 87Sr/ 86sr海水)的残差值Mann-Whitney U检验表明,古纬度和相关的沉积速率差异影响了海水87Sr/86Sr值在牙形刺中的保存。粘土矿物的相对丰度与中、低纬度沉积物中牙形刺的残值没有显著相关性。建议今后研究海水87Sr/86Sr记录时,采用牙形石磷灰石目标低纬、高沉积速率、CAI≤2的环境。
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引用次数: 0
Deciphering Holocene monsoon dynamics in northeastern India using speleothem δ18O record and petrography 利用洞穴δ18O记录和岩石学解读印度东北部全新世季风动力学
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-22 DOI: 10.1016/j.palaeo.2025.113518
Yachna Verma , Anil K. Gupta , Prasanta Sanyal , Priyantan Gupta , Som Dutt , Pankaj Kumar , Abhijit Mukherjee
A high-resolution stalagmite δ18O record from Mawsmai Cave (MAW), spanning from ∼11,807 to 5622 calibrated years before present (cal yr BP), sheds light on the dynamics of the Indian Summer Monsoon (ISM). In the early Holocene (∼ 11,807–7700 cal yr BP) the decreased δ18O values suggest a period of intensified ISM, whereas in the middle Holocene (∼ 7700–5622 cal yr BP) the positive δ18O values demonstrate a weak ISM. Petrographic and mineralogical analyses suggest a correspondence between changes in stalagmite fabric and δ18O variability, implying a climatic control on stalagmite growth. The MAW record also depicts several multi-centennial scale ISM shifts that coincide with the Bond events 8, 7, 6, 5b, 5a, and 4, suggesting teleconnections between North Atlantic climate and ISM variability via changes in the Atlantic Meridional Overturning Circulation (AMOC). Spectral and continuous wavelet transform analyses of the MAW record reveal periodicities of ∼118 and ∼ 110 years, consistent with the centennial-scale Gleissberg solar cycles. These cyclicities indicate that solar variability in conjunction with coupled ocean–atmosphere dynamics, including the Pacific Decadal Oscillation (PDO) and the temperature gradient between the Tibetan Plateau and the Indian Ocean, played a dominant role in modulating ISM variability during the early to middle Holocene.
Mawsmai洞穴(MAW)的高分辨率石笋δ18O记录,跨度为距今约11,807至5622校准年(cal yr BP),揭示了印度夏季风(ISM)的动力学。在全新世早期(~ 11,807 ~ 7700 cal yr BP), δ18O值的下降表明了ISM的增强,而在全新世中期(~ 7700 ~ 5622 cal yr BP), δ18O值的上升表明ISM的减弱。岩石学和矿物学分析表明,石笋结构的变化与δ18O变率之间存在对应关系,表明气候控制了石笋的生长。MAW记录还描述了与Bond事件8、7、6、5b、5a和4相吻合的几次百年尺度ISM变化,表明北大西洋气候与ISM变率之间通过大西洋经向翻转环流(AMOC)的变化存在远相关。MAW记录的光谱和连续小波变换分析显示周期为~ 118年和~ 110年,与百年尺度的Gleissberg太阳周期一致。这些周期表明,在全新世早期至中期,太阳变率与太平洋年代际涛动(PDO)和青藏高原与印度洋之间的温度梯度等海洋-大气耦合动力学在调节ISM变率中起主导作用。
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引用次数: 0
Corrigendum to “Orbital-scale palaeoclimate and palaeoceanographic evolution in the late Permian Western Hubei Trough, South China” [Palaeogeography, Palaeoclimatology, Palaeoecology (2025) 113466] “中国南方鄂西海槽晚二叠世轨道尺度古气候和古海洋演化”勘误表[古地理,古气候,古生态(2025)113466]
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-20 DOI: 10.1016/j.palaeo.2025.113507
Shuaicai Wu , Lei Chen , Wen Liu , Weiliang Kong , Min Xiong , Xiangyu Liu , Xiucheng Tan , Zuyou Zhang , Chongjie Liao
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引用次数: 0
Reduction in the rate of exhumation of the Gangdese Mountains (Tibetan Plateau) through the Neogene and its implications for crustal shortening of the Himalaya
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-18 DOI: 10.1016/j.palaeo.2025.113514
Jie Wei, An Wang, Tianyi Shen, Ganyu Lyu, Haoruo Li, Guocan Wang
During the Neogene, the crustal deformation in the southern Tibetan Plateau propagated southward from the Gangdese Mountains to the Himalaya. This propagation provides a perspective for exploring Himalayan crustal shortening and topographic development through the tectonic history of the Gangdese Mountains. In this paper, we present new thermochronological data (16 apatite (UTh)/He, 25 apatite fission-track, and 23 zircon fission-track ages) from the southern Gangdese Mountains, which delineate a detailed history of attenuating rates of exhumation during the Neogene. Specifically, the southern margin of the Gangdese Mountains is characterized by a rapid exhumation (∼1.08 mm/yr) in the early Miocene, followed by a moderate rate of ∼0.27 mm/yr between 16 and 11 Ma, and subsequently a steady, lower exhumation rate of ∼0.18 mm/yr since 11–8 Ma. These progressively decreasing exhumation rates, interpreted as tectonically driven and coupled with the southward propagation of deformation in the Himalaya, correspond to an inverse correlation in partitioned shortening rates between the Himalaya and the Gangdese Mountains. This relationship enables a first-order estimation of Himalayan crustal shortening based on the tectonically determined exhumation rate in the Gangdese Mountains. Our data and analysis estimate total Neogene crustal shortening of ∼417–522 km across Himalaya, consistent with previous structural studies. Crustal thickening predicted by this shortening supports the interpretation that the modern crustal thickness and paleoelevation of the Himalaya were largely attained by the late Miocene.
这种传播为通过冈底斯山脉的构造史研究喜马拉雅地壳缩短和地形发育提供了新的视角。本文介绍了冈底斯山脉南部16个磷灰石(UTh)/He年龄、25个磷灰石裂变径迹年龄和23个锆石裂变径迹年龄的热年代学资料,详细描述了冈底斯山脉南部新近纪的出土衰减速率。具体而言,冈底斯山脉南缘在中新世早期具有快速的出土速度(~ 1.08 mm/yr),随后在16 ~ 11 Ma之间有中等的出土速度(~ 0.27 mm/yr),随后在11 ~ 8 Ma以来有稳定的较低的出土速度(~ 0.18 mm/yr)。这些逐渐减少的掘出率被解释为构造驱动,并与喜马拉雅地区的变形向南传播相结合,对应于喜马拉雅和冈底斯山脉之间的分区缩短率呈负相关。这一关系使我们能够根据冈底斯山脉构造确定的掘出速率对喜马拉雅地壳缩短进行一阶估计。我们的数据和分析估计整个喜马拉雅地区新近纪地壳总缩短约417-522公里,与之前的结构研究一致。这一缩短预测的地壳增厚支持了喜马拉雅现代地壳厚度和古海拔主要在晚中新世达到的解释。
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引用次数: 0
New insights into the Neogene sedimentary Formations of south-western India: Implications for provenance, palaeovegetation and depositional environment 印度西南部新近纪沉积地层的新认识:物源、古植被和沉积环境的意义
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-18 DOI: 10.1016/j.palaeo.2025.113499
K.V. Sarath , K. Sandeep , Alka Absur , Namitha Ajay , Poonam Verma , Yogesh P. Singh , A.K. Rafaz , V. Nandakumar , G. Indu , E. Shaji
The Warkalli Formation represents a key Neogene sedimentary archive along the south-western coast of India. This study examines the northern extension of the Formation exposed around Cheruvathur village, Kerala, integrating sedimentological, geochemical, and palynological data to reconstruct provenance, weathering conditions, palaeovegetation, and depositional environment. The succession is composed of arenaceous–argillaceous sediments capped by laterite and is classified into four facies associations: floodplain, active channel, lagoonal/lacustrine, and dune–beach transition facies, indicating major shifts in fluvial dynamics and changes in the coastline. Extremely high values of Chemical Index of Alteration and Fe-Al enrichment suggest intense tropical chemical weathering and derivation from nearby felsic to intermediate basement rocks, with minor mafic contributions. Pollen spectra dominated by pteridophyte spores and angiosperm pollen, along with fungal remains, indicate warm and humid climatic conditions with freshwater to coastal vegetation and episodic tidal influence. These observations collectively imply strong monsoonal forcing, short sediment transport, and fluctuating sea levels during the Mio-Pliocene. The study provides new insights into Neogene palaeoenvironmental evolution along the passive western margin of India and highlights the climatic sensitivity of tropical coastal depositional systems.
瓦尔卡利组代表了印度西南海岸一个重要的新近纪沉积档案。本研究考察了喀拉拉邦Cheruvathur村附近暴露的组北延伸,综合沉积学、地球化学和孢粉学数据,重建了物源、风化条件、古植被和沉积环境。该序列由红土覆盖的砂质-泥质沉积物组成,并划分为四个相组合:洪泛平原、活动水道、泻湖/湖泊和沙丘-海滩过渡相,表明河流动力学和海岸线的主要变化。异常高的蚀变化学指数和Fe-Al富集表明强烈的热带化学风化作用和从附近长英质到中间基岩的演化,基性贡献较小。以蕨类植物孢子和被子植物花粉为主的花粉谱,以及真菌残留物,表明气候条件温暖潮湿,淡水到沿海植被和潮汐的间歇性影响。这些观测结果共同暗示了在中新世-上新世期间强烈的季风强迫、短暂的沉积物输运和波动的海平面。该研究为研究印度被动西缘新近纪古环境演化提供了新的见解,并突出了热带海岸沉积体系的气候敏感性。
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引用次数: 0
Mid-holocene environmental changes and glacial-isostatic uplift recorded in a coastal isolation basin on inexpressible Island, Ross Sea, Antarctica 南极罗斯海不可表达岛海岸隔离盆地中全新世环境变化与冰川均衡隆起记录
IF 2.7 2区 地球科学 Q2 GEOGRAPHY, PHYSICAL Pub Date : 2025-12-17 DOI: 10.1016/j.palaeo.2025.113516
Shuo Wang , Yuzhu Zhang , Ninglian Wang , Zhiheng Du , Yan Zhu , Peng Cheng , Yuda Chui
Antarctica's postglacial ice-free regions preserve sedimentary archives that are critical for reconstructing relative sea-level (RSL) changes and glacial-isostatic adjustment (GIA). This study presents a 37 cm sediment core from a coastal isolation basin (NYD Lake) on Inexpressible Island in Terra Nova Bay, Ross Sea. The basin's retaining sill is currently 1.1 m above mean sea level. The core spans the past ∼7400 calibrated years and captures a clear environmental transition from a tidal marine setting to a semi-enclosed lacustrine system. Three depositional units are identified: (1) a lower marine unit (below 18 cm; prior to ∼3500 cal yr BP) composed of coarse sand with high sulfur content, indicating strong tidal influence; (2) a transitional unit (18–7 cm) with mixed marine and freshwater signatures, reflecting gradual isolation; and (3) an upper lacustrine unit (above 7 cm; since ∼1700 cal yr BP), characterized by fine silt and organic geochemistry dominated by freshwater algal input but still subject to tidal or wave influence. C/N ratios and δ13C values indicate that the source of sedimentary organic matter shifted from a marine–terrestrial mixture to primarily freshwater algal origin after ∼1700 cal yr BP. This transition marks the isolation of the NYD Lake, coinciding with the sill emerging above sea level. Using the sill elevation and the timing of isolation, we estimate a crustal uplift rate of 0.65 ± 0.17 mm/yr. This record provides rare empirical constraints on Holocene RSL changes in the Terra Nova Bay and contributes to improving GIA models and understanding coastal evolution along the western Ross Sea margin.
南极洲冰期后无冰区保存着沉积档案,这些档案对于重建相对海平面(RSL)变化和冰川均衡调整(GIA)至关重要。本文研究了罗斯海特拉诺瓦湾不可表达岛(Inexpressible Island)海岸隔离盆地(NYD Lake)的37 cm沉积物岩心。目前,该盆地的挡土坝高出平均海平面1.1米。岩心跨越过去~ 7400校准年,捕捉了从潮汐海洋环境到半封闭湖泊系统的清晰环境转变。确定了3个沉积单元:(1)较低的海洋单元(低于18 cm;早于~ 3500 cal yr BP),由高含硫量的粗砂组成,表明潮汐的强烈影响;(2)过渡性单元(18-7厘米),具有海洋和淡水混合特征,反映出逐渐隔离;(3)上湖单元(7cm以上;自~ 1700 cal yr BP以来),特征为细粉砂和有机地球化学,以淡水藻类输入为主,但仍受潮汐或波浪影响。C/N比值和δ13C值表明,在~ 1700 cal yr BP之后,沉积有机质的来源从海陆生混合物转变为主要的淡水藻类来源。这种转变标志着纽约湖的孤立,与海平面以上的岩石相吻合。根据基台高程和隔离时间,我们估计地壳隆升速率为0.65±0.17 mm/yr。该记录为特拉诺瓦湾全新世RSL变化提供了罕见的经验约束,有助于改进GIA模型和理解罗斯海西部边缘的沿海演变。
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引用次数: 0
期刊
Palaeogeography, Palaeoclimatology, Palaeoecology
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