Global and Planetary Change最新文献_第7页

Late Ordovician arc-continent collision in the northernmost Tethyan-Ocean: Insights from detrital chromite and garnet geochemistry of the Koumenzi Formation in the Qilian Orogenic Belt 晚奥陶世特提斯洋最北端弧陆碰撞：祁连造山带口门子组碎屑铬铁矿和石榴石地球化学的启示

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-07 DOI: 10.1016/j.gloplacha.2026.105280

Hui Chen , Zhen Yan , Changlei Fu , Jonathan C. Aitchison

The Qilian Orogen in the northeastern margin of Qinghai-Tibetan plateau records the tectonic history of the Proto-Tethyan Ocean from its initial subduction to final closure. However, the timing of subduction initiation, subduction polarity, and arc-continent collision processes remain controversial. This study investigates detrital heavy mineral assemblages and geochemistry of 135 detrital chromite and garnet grains from nine sandstone samples of the Upper Ordovician Koumenzi Formation in a coastal tidal environment within the North Qilian Belt. The results reveal distinct spatial variations in mineral abundance: chromite is more prevalent in the northern samples compared to central and southern sections, while garnet abundance exhibits an inverse pattern, with the highest abundance observed in the central section. Compositional analyses reveal that the detrital chromites closely resemble those from North Qilian MOR- and forearc SSZ-type ophiolites, whereas garnets display geochemical affinities with high-pressure/low-temperature metamorphic rocks from the accretionary complex and amphibolite–granulite–facies metamorphic complex, suggesting a mixed provenance. Integrated with detrital compositions of sandstone and conglomerate, as well as a multiple flow system characterized by SEE to NEE- and NWW to W-ward currents, these data collectively support a dual source region involving both the North Qilian island arc–accretionary complex (NQIAC) and the Central Qilian Block (CQB). Based on the spatial-temporal evolution of the NQIAC and Andean-type margin of the CQB, we suggest that the Proto-Tethyan Ocean underwent bidirectional subduction between the CQB and the North Qilian island arc from ∼520 to 450 Ma, followed by a subduction polarity reversal during arc-continent collision at ∼450–440 Ma, triggering formation of a retro-foreland basin that received detritus from both the uplifted accretionary complex and the CQB.

青藏高原东北缘祁连造山带记录了原特提斯洋从开始俯冲到最终闭合的构造历史。然而，对俯冲起始时间、俯冲极性和弧陆碰撞过程仍有争议。研究了北祁连带滨海潮汐环境下上奥陶统口门子组9个砂岩样品中135粒铬铁矿和石榴石碎屑重矿物组合及地球化学特征。结果显示，矿物丰度存在明显的空间差异：与中部和南部相比，铬铁矿在北部样品中更为普遍，而石榴石丰度呈现相反的模式，在中部样品中丰度最高。碎屑铬铁矿与北祁连MOR和弧前ssz型蛇绿岩相似，而石榴石则与增生杂岩和角闪岩-麻粒岩相变质杂岩的高压/低温变质岩具有地球化学亲和性，表明其物源混合。结合砂岩和砾岩的碎屑成分，以及以SEE - NEE、NWW -w向流为特征的多流体系，这些数据共同支持了北祁连岛弧-增生杂岩（NQIAC）和中祁连地块（CQB）的双源区。基于NQIAC和CQB的安第斯型边缘的时空演化，我们认为在~ 520 ~ 450 Ma期间，原特提斯洋在CQB和北祁连岛弧之间经历了双向俯冲，然后在~ 450 ~ 440 Ma期间弧-大陆碰撞期间发生了俯冲极性反转，引发了一个后前陆盆地的形成，该盆地同时接受了上升的增生杂岩和CQB的碎屑。

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引用次数: 0

Basin record of Paleogene plateau development in eastern Tibet 西藏东部古近系高原发育的盆地记录

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-06 DOI: 10.1016/j.gloplacha.2026.105285

Xudong Zhao , Huiping Zhang , Ying Wang , Jianzhang Pang , Yifei Li , Jingxing Yu , Jianguo Xiong , Peizhen Zhang

The emergence of high topography in eastern Tibet is a critical expression of the eastward expansion of the Tibetan Plateau. However, both the timing and underlying mechanisms of this surface uplift remain incompletely understood and subject to ongoing debate. Sedimentary basin fills, as direct products of surface erosion, offer valuable archives for reconstructing paleo-landscapes and tracking topographic evolution. In this study, we present new detrital zircon UPb and apatite fission-track data from non-marine Cenozoic strata of the Shiqu Basin—an isolated intermontane basin situated within the interior of eastern Tibet—to constrain depositional age and sediment provenance. Our data indicate that basin deposition occurred primarily during the Eocene to Early Oligocene, with sediments sourced predominantly from the southeastern Songpan-Ganzi terrane. Integration with regional bedrock thermochronology and stratigraphic records from coeval basins in the southeastern Tibetan Plateau suggest that the development of significant topography in eastern Tibet had already initiated by the Eocene. By the Late Eocene to Early Oligocene, this region had likely evolved into a high-elevation, eastward-tilting landscape similar to that observed today. We infer that this phase of plateau growth was primarily driven by large-scale crustal shortening, potentially coupled with localized crustal flow.

西藏东部高地形的出现是青藏高原东扩的重要表现。然而，这种表面隆起的时间和潜在机制仍然不完全清楚，并受到持续争论的影响。沉积盆地填充物作为地表侵蚀的直接产物，为重建古地貌和追踪地形演化提供了宝贵的资料。本文利用藏东地区石曲盆地新生代非海相地层的碎屑锆石UPb和磷灰石裂变径迹资料，对其沉积时代和物源进行了限定。盆地沉积主要发生在始新世至早渐新世，沉积物主要来自松潘—甘孜地体东南部。结合青藏高原东南部同古盆地的区域基岩热年代学和地层记录，表明青藏高原东部重要地形的发育始于始新世。在始新世晚期到渐新世早期，这一地区很可能演变成一个高海拔、向东倾斜的景观，与今天所观察到的相似。我们推断，这一阶段的高原生长主要是由大规模地壳缩短驱动的，可能与局部地壳流动相结合。

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引用次数: 0

Astronomically paced Katian (late Ordovician) sea-level changes: A record from Northern Yangtze Block 天（晚奥陶世）海平面变化的天文节奏：北扬子地块的记录

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-05 DOI: 10.1016/j.gloplacha.2026.105283

Chuanzhen Ren , Qiang Fang , Huaichun Wu , Wentao Huang , Xiuchun Jing , Jinlin Liu , Ziyu Wang , Congcong Gai , Meinan Shi , Tianshui Yang , Haiyan Li

Astronomical forcing is recognized as a significant external driver influencing sea-level changes under both typical icehouse and greenhouse conditions; however, mechanisms underlying this forcing remain ambiguous in the context of such climatic transition. The Katian represents a key stage characterized by a gradual shift from Sandbian greenhouse to Hirnantian icehouse conditions in late Ordovician. Here, we conducted sedimentological and cyclostratigraphic analyses on the Katian Shiyanhe Formation at Sigang section in the Northern Yangtze Block, aiming to elucidate the forcing mechanisms of sedimentary processes during a period of climatic transition. Five microfacies zones comprising eight microfacies were identified, and these collectively indicate a mixed shelf sedimentary environment in which three third-order and nine fourth-order depositional sequences were developed. Cyclostratigraphic analyses of magnetic susceptibility (MS), calcium (Ca), and lithological rank series reveal robust Milanković cycle signals, including 405-kyr long eccentricity, 91–106-kyr short eccentricity, 32.4–33.4-kyr obliquity, and 17.5–21.6-kyr precession cycles. A newly constructed astronomical time scale calibrates the duration of third- and fourth-order depositional sequences as ∼1.2 Myr and ∼405 kyr, respectively corresponding to the long-period obliquity and long eccentricity cycles. The cause-and-effect relationship between these cycles and sea-level changes was further corroborated through the sedimentary noise modeling of MS and Ca data. In addition, a pronounced imprint of the obliquity cycle is evident in the middle Aphelognathus grandis conodont biozone (viz., 448.5–449.7 Ma). This interval coincides with sea-level fall and the reported ice sheet growth at Gondwana, indicative of an enhanced teleconnection between the low and high latitudes driven by global cooling. Our study highlights the controlling effects of different astronomical cycles on the sedimentary processes during the climatic transition of stepwise cooling.

在典型的冰窖和温室条件下，天文强迫被认为是影响海平面变化的重要外部驱动力；然而，在这种气候转变的背景下，这种强迫的机制仍然不明确。卡天期是晚奥陶世从沙边温室条件逐渐向希尔南天冰窖条件转变的关键阶段。本文对北扬子地块四岗剖面卡田石沿河组进行了沉积学和旋回地层学分析，旨在阐明气候过渡时期沉积过程的强迫机制。识别出5个微相带，共发育8个微相，为陆架混合沉积环境，发育3个三级层序和9个四级层序。磁导率（MS）、钙（Ca）和岩性序列的旋回地层分析显示了milankovovic旋回信号，包括405-kyr长偏心率、91-106-kyr短偏心率、32.4-33.4-kyr倾角和17.5-21.6-kyr进动旋回。新建立的天文时标将三阶和四阶沉积序列的持续时间分别校准为~ 1.2 Myr和~ 405 kyr，对应于长周期倾角和长偏心旋回。通过MS和Ca数据的沉积噪声模拟进一步证实了这些旋回与海平面变化之间的因果关系。此外，在大尖形牙形石中部（448.5 ~ 449.7 Ma）具有明显的倾角旋回印记。这一间隔与海平面下降和冈瓦纳冰盖的增长相吻合，表明在全球变冷的驱动下，低纬度和高纬度之间的远距联系增强了。我们的研究强调了在逐步变冷的气候转变过程中，不同的天文周期对沉积过程的控制作用。

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引用次数: 0

Carbonate-associated phosphate evidence for a small inorganic phosphorus reservoir in the terminal Ediacaran ocean 埃迪卡拉末期海洋中一个小型无机磷储层的碳酸盐岩伴生磷酸盐证据

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-05 DOI: 10.1016/j.gloplacha.2026.105284

Yonghan Fan , Meng Cheng , Xinyang Chen , Catherine Rose , Haiyang Wang , Zihu Zhang , Thomas J. Algeo , Chao Li

The terminal Ediacaran (ca. 551–533 Ma) was characterized by profound biological innovations and environmental upheavals, in which phosphorus (P)—the ultimate limiting nutrient for marine productivity—is postulated to have played a key role. However, P availability in the terminal Ediacaran ocean remains uncertain due to the lack of an appropriate proxy record. To better reconstruct seawater P levels during this time interval, we analyzed carbonate-associated phosphate [CAP; expressed as CAP/(Ca + Mg)], a new proxy for P availability in ancient oceans, in three upper Ediacaran successions: the Nama Group (Namibia), the Shibantan Member of the Dengying Formation (Wuhe, South China), and the Algal Dolomite, Gaojiashan and Beiwan members of the Dengying Formation (Gaojiashan, South China). Our results reveal consistently low CAP/(Ca + Mg) values (range: 0.02–0.69 mmol/mol, mean: 0.13 ± 0.01 mmol/mol, 2σ, the same below) for all study sections, falling at the lower end of modern marine carbonate values. Lithofacies, carbonate oxygen isotopes, Mn/Sr and Mg/(Mg + Ca) ratios indicate possible influences from release of Fe-bound P, meteoric diagenesis, recrystallization or dolomitization. The low CAP/(Ca + Mg) values thus represent a maximum estimate for the seawater P availability. The low CAP values from two geographically separated cratons likely reflect a generally small oceanic inorganic P reservoir at least in shelves. This study provides insights into the interplay between nutrient cycling, redox dynamics, and biological evolution during one of the most pivotal transitional periods in Earth history.

埃迪卡拉纪末期（约551-533 Ma）以深刻的生物创新和环境剧变为特征，其中磷(P)——海洋生产力的最终限制营养物质——被认为发挥了关键作用。然而，由于缺乏适当的代理记录，埃迪卡拉纪晚期海洋的P可用性仍然不确定。为了更好地重建这段时间内的海水P水平，我们分析了碳酸盐岩相关磷酸盐[CAP；表示为CAP/(Ca + Mg)]，这是古海洋磷有效性的新代表，在三个上埃迪卡拉系序列中：Nama组（纳米比亚）、灯影组Shibantan组（中国南方五河）和灯影组高家山和北湾组藻类白云岩（中国南方高家山）。我们的研究结果显示，所有研究剖面的CAP/(Ca + Mg)值始终较低（范围：0.02-0.69 mmol/mol，平均值：0.13±0.01 mmol/mol, 2σ，下同），处于现代海相碳酸盐岩值的低端。岩相、碳酸盐氧同位素、Mn/Sr和Mg/(Mg + Ca)比值表明铁结合P的释放、大气成岩作用、再结晶或白云化作用可能对其产生影响。因此，较低的CAP/(Ca + Mg)值代表了对海水磷有效性的最大估计。两个地理上分离的克拉通的低CAP值可能反映了至少在陆架中普遍存在较小的海洋无机磷储层。这项研究为地球历史上最关键的过渡时期之一的营养循环、氧化还原动力学和生物进化之间的相互作用提供了见解。

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引用次数: 0

Alternating trench advance and retreat in the North Tianshan Ocean: Insights from Carboniferous magmatism in the Aqishan-Yamansu Belt, Chinese Eastern Tianshan 北天山洋海沟交替进退：来自中国东天山阿奇山—亚曼苏带石炭系岩浆活动的启示

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-05 DOI: 10.1016/j.gloplacha.2026.105282

Guoliang Xue , Huan Kang , Yuelong Chen , Dapeng Li , Jiarun Tu , Wenjun Zheng , Xiaoran Zhang

Trench advance-retreat cycles serve as the primary regulators of continental crustal growth and the thermal-mechanical evolution of accretionary orogens. This study deciphered Carboniferous trench kinematics in the Chinese Eastern Tianshan through a spatiotemporal investigation of magmatism within the Aqishan-Yamansu Belt. Two distinct magmatic episodes were identified, i.e., the middle Mississippian arc-related high-Mg andesitic porphyrite and the early Pennsylvanian high-Al basalt. Geochemical and isotopic data revealed that these magmas were originated from varying degrees of interaction among depleted mantle, mantle wedge, and subducted slab−/sediment-derived fluids/melts. Integration with the regional geological context and the time-resolved compositional and geochemical shifts in arc magmatism indicated recurrent trench migration cycles. The trench advance phases (Early Carboniferous and Late Pennsylvanian) were marked by voluminous arc magmatism, elevated Ho/Yb–Dy/Yb ratios, reduced whole-rock ε_Nd(t) and zircon ε_Hf(t) values, and older zircon Hf crustal model ages (T_DM^C), collectively implying intensified crustal contributions. Conversely, the trench retreat (from latest Mississippian to middle Pennsylvanian) was characterized by back-arc basalts, diminished Ho/Yb–Dy/Yb ratios, elevated whole-rock ε_Nd(t) and zircon ε_Hf(t), and younger zircon Hf model ages (T_DM), suggesting the enhanced mantle input. This retreat phase triggered splitting of the Central Tianshan arc and formation of the Aqishan-Yamansu back-arc basin. Our findings suggest that the southward subduction of the North Tianshan oceanic slab governed trench migration cycles, thereby orchestrating the transition from an Early Carboniferous continental arc to a Late Carboniferous back-arc basin. Continued subduction culminated in latest Carboniferous collision, closing the trench-arc-basin system and finalizing the assembly of the Chinese Eastern Tianshan. These results underscored that episodic trench migration cycles reconstructed through magmatic and elemental-isotopic records constituted a critical mechanism for accretionary orogenesis driven by mantle dynamics. Ultimately, such cyclic processes controlling tectonic transitions and ocean closure represent key factors in continental crust formation within accretionary orogens.

海沟进退旋回是大陆地壳生长和增生造山带热力学演化的主要调节机制。本文通过对阿奇山—亚曼苏岩浆活动的时空调查，破译了中国东天山石炭系海沟运动学。发现了两个不同的岩浆期，即中密西西比世与弧相关的高镁安山岩斑岩和早宾夕法尼亚世高铝玄武岩。地球化学和同位素数据表明，这些岩浆起源于贫地幔、地幔楔和俯冲的板岩/沉积流体/熔体之间不同程度的相互作用。结合区域地质背景和弧岩浆活动的时间分辨成分和地球化学变化，表明海沟迁移周期反复出现。海沟推进期（早石炭世和晚宾夕法尼亚世）弧岩浆活动剧烈，Ho/Yb - dy /Yb比值升高，全岩εNd(t)和锆石εHf(t)值降低，锆石Hf地壳模式年龄（TDMC）变老，表明地壳贡献增强。相反，从密西西比晚期到宾夕法尼亚中期，海沟后退以弧后玄武岩为特征，Ho/Yb - dy /Yb比值降低，全岩εNd(t)和锆石εHf(t)升高，锆石Hf模式年龄（TDM）更年轻，表明地幔输入增强。这一撤退阶段引发了中天山弧的分裂，并形成了阿奇山-亚曼苏弧后盆地。北天山洋板向南俯冲控制了海沟迁移旋回，从而协调了早石炭世大陆弧向晚石炭世弧后盆地的转变。持续的俯冲作用在石炭纪晚期碰撞中达到顶峰，关闭了沟-弧-盆地体系，完成了中国东天山的组装。这些结果表明，通过岩浆和元素同位素记录重建的幕式海沟迁移旋回是地幔动力学驱动的增生造山作用的重要机制。最终，这种控制构造转换和海洋闭合的旋回过程是增生造山带内大陆地壳形成的关键因素。

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引用次数: 0

Precession-dominated summer insolation forcing of East Asian monsoon precipitation since 1.2 Ma: Insights from the Weihe Basin, Central China 1.2 Ma以来以岁差为主导的东亚季风降水夏季日照强迫：来自渭河盆地的启示

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-03 DOI: 10.1016/j.gloplacha.2026.105281

Xuke He , Yougui Song , Yue Li , Jianhong Xu , Xiaofen Fu , Huifang Liu , Qingliang Wang , Yixiao Han

The Asian monsoon is crucial for sustaining billions of people, yet its geological history, primary drivers, and mechanisms remain contentious. To explore the potential driving mechanisms of East Asian summer monsoon (EASM) precipitation since the Early Pleistocene, we here present data from a 272-m-long core of Quaternary lacustrine–fluvial–aeolian sediments from the Weihe Basin in central China. The chronology of the core is established through magnetostratigraphy and tie-point matching with speleothem oxygen isotope (δ¹⁸O) curves. Lithofacies and geochemical profiles reveal that the core records a sedimentary succession from lacustrine through fluvial to aeolian depositional environments since 1.18 Ma. End-member (EM) modeling of lacustrine deposits shows that the transport and deposition of coarse EM3, EM4, and EM5 components are linked to vigorous nearshore hydrodynamics. Consequently, the summed proportion of these three EMs serves as an indicator of monsoon-induced paleolake transgressions and regressions. Reduced precipitation causes lake contraction, and the development of littoral lake sub-facies enriched in coarse EM components. Hydrodynamic sorting, modulated by catchment hydrology, imparted a precession signal to lacustrine bulk-sediment XRF element intensities. On orbital timescales, EASM precipitation variations are governed by precession-dominated boreal-summer insolation. Featuring a robust chronology and sensitive response of lacustrine proxies to precipitation, our findings confirm that insolation forcing fundamentally governs precipitation patterns in East Asia.

亚洲季风对维持数十亿人的生计至关重要，但其地质历史、主要驱动因素和机制仍存在争议。为了探讨早更新世以来东亚夏季风（EASM）降水的潜在驱动机制，我们利用了中国中部渭河盆地第四纪湖-河-风成沉积物的272米长的岩心数据。通过磁地层学和与岩心氧同位素（δ18O）曲线的结合点拟合，确定了岩心的年代学。岩石相和地球化学剖面显示，该岩心记录了1.18 Ma以来湖泊-河流-风成沉积环境的沉积序列。湖泊沉积物的端元（EM）模拟表明，粗EM3、EM4和EM5组分的搬运和沉积与剧烈的近岸水动力有关。因此，这三个em的总和比例可以作为季风引起的古湖泊海侵和回归的指标。降水减少导致湖泊收缩，形成富含粗EM组分的滨海湖泊亚相。受流域水文调节的水动力分选为湖泊体沉积物XRF元素强度提供了进动信号。在轨道时间尺度上，东亚地区降水变化受进动主导的寒夏日晒的支配。具有强大的年代学和湖泊代用物对降水的敏感响应，我们的研究结果证实了日照强迫从根本上控制了东亚的降水模式。

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引用次数: 0

Reconstruction of last millennium sea surface temperature on 1° grid using a random forest algorithm 用随机森林算法重建1°网格上近千年海面温度

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2026-01-03 DOI: 10.1016/j.gloplacha.2025.105279

Simon L.L. Michel , Didier Swingedouw , Juliette Mignot

Climate models and theoretical evidence show that the ocean drives climate from sub-decadal to centennial timescales through a variety of processes and their interactions. The range of direct climate observations, arelhowever, is too short to understand the exact role of the ocean in shaping observed and future climate variability on top of anthropogenic climate change. In the present study, we use a large set of paleoclimate records combined with a random forest algorithm to reconstruct a gridded dataset of sea surface temperatures since 850 C.E. to provide a better framework for the study of ocean surface variability. In line with modeling and paleodata studies, our reconstruction suggests that natural climate forcings have importantly influenced the last millennium climate variability. Our reconstruction also suggests that North Atlantic SST multidecadal variability influences Pacific SST on decadal timescales. However, the latter result is shown to be strongly dependent on background climate conditions. This new reconstruction offers a useful resource for testing the capabilities of climate models to reproduce the linkages between Atlantic and Pacific as well as the response to external forcings.

气候模式和理论证据表明，海洋通过各种过程及其相互作用驱动着从次年代际到百年代际的气候。然而，直接气候观测的范围太短，无法理解海洋在人为气候变化之外塑造已观测到的和未来的气候变率方面的确切作用。本研究利用大量的古气候记录，结合随机森林算法重建了850 C.E.以来的海洋表面温度网格数据集，为研究海洋表面变率提供了一个更好的框架。与模拟和古数据研究一致，我们的重建表明，自然气候强迫对过去一千年的气候变率有重要影响。我们的重建也表明北大西洋海温的多年代际变化在年代际时间尺度上影响太平洋海温。然而，后一种结果在很大程度上取决于背景气候条件。这种新的重建为测试气候模式再现大西洋和太平洋之间的联系以及对外部强迫的反应的能力提供了有用的资源。

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引用次数: 0

Holocene climate optimum moisture variability in the monsoon marginal zone of northern China revealed by multi-proxy stalagmite records 多代石笋记录揭示的中国北方季风边缘区全新世气候最适湿度变率

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-12-30 DOI: 10.1016/j.gloplacha.2025.105278

Shouyi Huang , Yanjun Cai , Gang Xue , Xinhui Zhang , Mei He , Ruoxin Li , Yingying Wei , Le Ma , Xing Cheng , Haiwei Zhang , Hai Cheng

Reconciling the diverse climate responses of various geological archives poses a challenge for a comprehensive understanding of the Holocene climate change in East Asia. Here, we present multi-proxy records of two precisely dated stalagmites from the northeastern Chinese Loess Plateau. A comparative analysis reveals that the main depositional period (∼9.6–5.9 ka BP) of one stalagmite directly corresponds to the Holocene Climate Optimum (HCO) in northern China. The stalagmite δ¹⁸O exhibits a quasi-500-year cyclicity throughout the HCO, which aligns with other records from the North Atlantic, East Asia, and Mediterranean during the cycle from ∼8.3 to 7.8 ka BP, likely reflecting the 8.2 ka event's imprint. Meanwhile, divergent phase relationships occurred during other intervals, indicating regionally distinct responses to solar-driven coupled ocean-atmosphere oscillations. Furthermore, multiple hydroclimate proxies and the stalagmite growth rate from the same stalagmite reveal a shift in the precipitation regimes, manifested as the rainy season extending from summer to autumn after ∼7.8 ka BP. Changes in the position and intensity of the subtropical westerly jet may drive this shift.

协调各种地质档案的不同气候响应对全面认识东亚全新世气候变化提出了挑战。本文报道了中国东北黄土高原两种石笋的多代用记录。对比分析表明，某石笋的主要沉积期（~ 9.6 ~ 5.9 ka BP）与中国北方全新世气候适宜期（HCO）直接对应。石笋δ18O在整个HCO中表现出准500年的周期，这与北大西洋、东亚和地中海的其他记录在~ 8.3 ~ 7.8 ka BP的周期内一致，可能反映了8.2 ka事件的印记。与此同时，在其他时段出现了发散的相位关系，表明对太阳驱动的海洋-大气耦合振荡的区域响应不同。此外，多种水文气候指标和来自同一石笋的石笋生长速率揭示了降水制度的变化，表现为在~ 7.8 ka BP之后，雨季从夏季延长到秋季。副热带西风急流的位置和强度的变化可能驱动这种转变。

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引用次数: 0

Oceanic deoxygenation linked to enhanced water column stratification in the eastern Tethys during Cretaceous Oceanic Anoxic Event 2 白垩纪海洋缺氧事件2期间，特提斯东部的海洋脱氧与水柱分层增强有关

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-12-29 DOI: 10.1016/j.gloplacha.2025.105270

Yu Liang , Yong-Xiang Li , Hongxuan Lu , Huanye Wang , Cece Wang , Cheng Quan , Weiguo Liu , Mei-Fu Zhou , Zhonghui Liu

The mid-Cretaceous Oceanic Anoxic Event 2 (OAE2, ∼94 Ma) stands as a prominent deep-time analogue for understanding global oceanic redox variations in response to major environmental perturbations. However, the mechanisms driving oceanic redox evolution in the eastern Tethys during OAE2, particularly the influence of water column stratification, remain poorly investigated. In this study, we analyze the connections between oceanic redox, stratification, and productivity changes in the eastern Tethys during OAE2 using biomarker records of glycerol dialkyl glycerol tetraethers (GDGTs) and n-alkanes from the Gongzha section, southern Tibet. Our results reveal pronounced increases in oceanic deoxygenation and stratification, alongside reduced productivity, through the carbon isotope stage C4, the main phase of OAE2 following the initial perturbation and prior to the recovery. Combining these findings with existing geological data from the Gongzha section, we infer that enhanced water column stratification may have driven the oceanic deoxygenation by diminishing ocean-atmosphere exchange in the eastern Tethys during OAE2. This mechanism differs from that previously observed in the circum-proto-North Atlantic, where increased productivity and associated enhancement in the organic remineralization may have triggered the marine anoxia. By providing biological constraints, our study indicates the dominant role of water column structure in shaping redox evolution in the eastern Tethys, highlighting distinct regional controls on oceanic redox evolution during OAE2.

中白垩纪海洋缺氧事件2 （OAE2, ~94 Ma）是了解全球海洋氧化还原变化对主要环境扰动响应的重要深时间模拟。然而，在OAE2期间，特提斯东部海洋氧化还原演化的驱动机制，特别是水柱分层的影响，仍然缺乏研究。本文利用藏南贡扎剖面的甘油二烷基甘油四醚（GDGTs）和正构烷烃的生物标志物记录，分析了OAE2期间特提斯东部海洋氧化还原、分层和生产力变化之间的联系。我们的研究结果表明，在碳同位素阶段C4 （OAE2在初始扰动之后和恢复之前的主要阶段），海洋脱氧和分层显著增加，同时生产力降低。结合公闸剖面已有的地质资料，我们推测在OAE2期间，特提斯东部水柱分层增强可能通过减少海气交换来驱动海洋脱氧。这一机制与之前在北大西洋周围观察到的机制不同，在北大西洋周围，生产力的提高和有机再矿化的相关增强可能引发了海洋缺氧。通过提供生物学约束，我们的研究表明水柱结构在塑造特提斯东部氧化还原演化中起主导作用，突出了OAE2期间海洋氧化还原演化的明显区域控制作用。

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引用次数: 0

Small-scale high-temperature metamorphic core-complexes: From nappe stacking to orogen parallel extension and subsequent thrusting in the Megina dome of North Dobrogea orogen 小型高温变质岩心杂岩：从推覆堆积到造山带平行伸展及其后的逆冲

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change

Pub Date : 2025-12-29 DOI: 10.1016/j.gloplacha.2025.105276

Andreea Marza-Ene , Liviu Matenco , Hannah Pomella , Vlad Victor Ene , Ioan Munteanu , Anneke Royakkers

Orogenic extension has been demonstrated to generate lower crustal exhumation observed in metamorphic core complexes. Observations and modelling have shown that orogen parallel extensional domes are challenging to constrain due to the superposition with coeval or subsequent geodynamic processes, such as orogenic thrusting, magmatism, or the evolution of subducted slabs. We utilise outcrop and micro scale observations to structurally quantify the original nappe stack burial and extensional exhumation structures of one such dome in the Măcin unit of the European North Dobrogea orogen. The results demonstrate an initial top to NE nappe stacking associated with the previously defined Late Carboniferous – Permian burial metamorphism, which affected a mafic protolith and its sedimentary cover. This burial was followed by Triassic extensional exhumation, retrograde metamorphism, magmatism and top to SE ductile shearing, which created a newly identified major detachment and orogen-parallel extensional dome. The kinematic study is furthermore complemented by a low-temperature fission track thermochronology performed to discriminate the extensional exhumation from the effects of subsequent thrusting. The thermochronology demonstrates that the Triassic extensional dome was subsequently affected by a Jurassic–Early Cretaceous exhumation, which is a novel quantification of the previously defined Cimmerian thrusting. Our results infer a new interpretation of the Măcin unit as a Palaeotethys ophiolitic suture zone, which contains a typical Hercynian metamorphic core-complex of relatively small dimensions. When compared with other similar larger structures observed elsewhere, our results show that small-scale orogen-parallel extensional domes can also develop at high temperatures during or after the main stage of nappe stacking metamorphism.

在变质岩心杂岩中，造山带伸展作用已被证实产生下地壳掘出。观测和模拟表明，由于与同期或随后的地球动力学过程（如造山逆冲、岩浆活动或俯冲板块的演化）的叠加，造山带平行伸展穹丘很难约束。我们利用露头和微观尺度的观测，对欧洲北多布罗格造山带马利辛单元的一个这样的巨丘的原始推覆层埋藏和伸展掘出构造进行了结构量化。研究结果表明，晚石炭世—二叠世埋藏变质作用影响了基性原岩及其沉积盖层，形成了由上至北东向推覆体的初始叠加。三叠纪伸展掘出、逆变质作用、岩浆作用和顶部至东南韧性剪切作用，形成了新发现的大拆离和与造山带平行的伸展丘。低温裂变径迹热年代学进一步补充了运动学研究，以区分伸展发掘和随后的逆冲作用。热年代学表明，三叠纪伸展丘随后受到侏罗纪-早白垩世掘出的影响，这是对先前定义的西元叠世逆冲构造的一种新的量化。我们的研究结果推断出一种新的解释，即马利辛单元是一个古特提斯蛇绿岩缝合带，其中包含一个典型的海西期相对较小的变质核杂岩。与其他地区观测到的类似大型构造相比，我们的研究结果表明，小规模的平行造山带伸展穹丘也可以在推覆堆积变质主阶段或之后的高温下发育。

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引用次数: 0