Palaeogeography, Palaeoclimatology, Palaeoecology最新文献

{"title":"Dynamics of the Arabian Sea thermocline and monsoon-climate coupling mechanisms over the past 55,000 years: Multi-proxy paleoenvironmental reconstruction","authors":"Feng Wang ,&nbsp;Yunhai Li ,&nbsp;Min Chen ,&nbsp;Xuan Ding ,&nbsp;Yunpeng Lin","doi":"10.1016/j.palaeo.2026.113544","DOIUrl":"10.1016/j.palaeo.2026.113544","url":null,"abstract":"<div><div>This study systematically reconstructed the variations in the thermocline of the Arabian Sea over the past 55,000 years and its responsive relationships with global climate events through multi-proxy analyses (including planktonic foraminiferal assemblages, Mg/Ca temperature reconstruction, carbonate content, and fragment rate, etc.) of the CJ08–22 sediment core from the Arabian Basin in the northwestern Indian Ocean. During the MIS3 stage (40–29 ka), the thermocline depth exhibited significant fluctuations, with the sea surface-thermocline temperature difference (ΔT) varying synchronously with Dansgaard-Oeschger (D<img>O) events. Enhanced Indian summer monsoons during warm periods led to weakened upwelling (decreased ΔT), whereas intensified winter monsoons during cold periods triggered strengthened upwelling (increased ΔT). During the MIS2 glacial maximum (29–14 ka), the thermocline shallowed with stably high ΔT, reflecting persistent upwelling driven by strong winter monsoons and deep-water acidification (minimum CaCO₃ content). In the MIS1 Holocene (14 ka–), the thermocline deepened, with ΔT consistent with solar insolation. During the 8.2 ka event, the monsoon weakened in the short to medium term. After the establishment of the modern monsoon system, the upwelling intensified again. Principal component analysis of planktonic foraminifera reveals the antagonistic distribution between warm current species (such as <em>Globigerinoides ruber</em>) and upwelling species (such as <em>Globigerina bulloides</em>), suggesting the synergistic effect of the monsoon-driven Arabian Current and Ekman pumping. The thermocline variations in the Arabian Sea showed significant correlations with North Atlantic D<img>O events, the Heinrich 1 event, and solar orbital forcing (20 ka precession cycle), indicating that high-latitude ice volume changes regulate low-latitude oceanic processes through atmospheric circulation (e.g., winter monsoons). This study provides new evidence for understanding the key role of the Arabian Sea in glacial-interglacial cycles, emphasizing that thermocline dynamics serve as a critical hub linking regional monsoon responses to global climate changes, which has implications for predicting the evolution of the Indian Ocean-monsoon system under future global warming.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113544"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927943","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}

{"title":"Middle Eocene hyperthermal seasonality from Paris Basin marine mollusks","authors":"Loïc Marlot ,&nbsp;Damien Huyghe ,&nbsp;Justine Briais ,&nbsp;Mathieu Daëron ,&nbsp;Christine Flehoc ,&nbsp;Laurent Emmanuel ,&nbsp;Didier Merle ,&nbsp;Olivier Aguerre-Chariol ,&nbsp;Franck Lartaud","doi":"10.1016/j.palaeo.2026.113547","DOIUrl":"10.1016/j.palaeo.2026.113547","url":null,"abstract":"<div><div>The Earth has experienced hyperthermal events in the past, characterized by maximum durations of hundreds thousand years, significant magnitude, global extent, and drivers associated with increases in greenhouse gas concentrations, therefore making them potential analogues for current climate change. The Middle Eocene Climatic Optimum (MECO) that occurred 40 Ma ago, is marked by a CO₂-driven global warming of +4 to +6 °C, affecting global temperatures. Here, we present a detailed reconstruction of seasonal fluctuations in seawater temperatures during this warming event in littoral environment, based on geochemical analyses (δ¹⁸O and ∆₄₇) of shallow-marine mollusks from the Paris Basin. Our data show a stability in mean winter temperatures compared to pre-MECO conditions, but a marked warming of +10 °C in maximum estuarine water temperatures, with a seasonal temperature range increasing from 12 °C before the MECO to 22 °C at the climax of the event. We demonstrate that at mid-latitudes, annual maximum shallow-water temperatures increased from 30 ± 2 °C before the event to a maximum of 41 ± 4 °C at the warming peak. This pattern is associated with a seasonal regime characterized by dry summers and wet winters, implying that the Paris Basin experienced a super-hot summer Mediterranean climate during the MECO.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113547"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927940","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}

{"title":"Factors affecting 87Sr/86Sr preservation in conodont apatite: An example from the Ordovician of Baltoscandia","authors":"Christopher T. Conwell ,&nbsp;Matthew R. Saltzman ,&nbsp;Anders Lindskog ,&nbsp;Mats E. Eriksson ,&nbsp;Elizabeth M. Griffith ,&nbsp;Stephen A. Leslie ,&nbsp;Cole T. Edwards ,&nbsp;Olle Hints ,&nbsp;Achim D. Herrmann","doi":"10.1016/j.palaeo.2025.113524","DOIUrl":"10.1016/j.palaeo.2025.113524","url":null,"abstract":"<div><div>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.</div><div>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/⁸⁶Sr_conodont – ⁸⁷Sr/⁸⁶Sr_seawater) 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.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113524"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145872109","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}

{"title":"Enhanced Asian monsoon hydroclimate instability during the mid-DO21","authors":"Ziqi Mu ,&nbsp;Tian Ma ,&nbsp;Hao Lu ,&nbsp;Dianbing Liu","doi":"10.1016/j.palaeo.2025.113519","DOIUrl":"10.1016/j.palaeo.2025.113519","url":null,"abstract":"<div><div>The internal structure of Dansgaard-Oeschger (DO) events and its regional correlation provide key insights into climate anomalies under stable conditions, but remain poorly constrained due to geologic proxy uncertainties. Here a high-resolution stalagmite (∼ 9-year-resloved) δ¹⁸O record from Jiangjun Cave, central China was presented to reconstruct Asian summer monsoon (ASM) history across Marine Isotope Stage (MIS) 5a/4 (83–71 thousand years before present, ka). Our result revealed a two-phase structure of ASM variability during mid-DO21. Between 82.8 and 80.4 ka (Phase I), limited δ¹⁸O variance indicated relatively stable ASM intensity. Between 80.4 and 78.8 ka (Phase II), a ∼ 1.4-fold increase in decadal- to centennial-scale δ¹⁸O fluctuations reflected enhanced ASM variability. However, the δ¹⁵N-inferred Greenland temperature was higher and exhibited greater oscillations during the early mid-DO21, followed by a cooling and muted variability later, indicating opposite high- and low-latitude patterns during mid-DO21. We proposed that sea ice dynamics and Atlantic Meridional Overturning Circulation (AMOC) strength modulated the migration of Westerly jet, which in turn governed the inland moisture transport into the ASM region. During Phase I, a northerly-positioned Westerly jet amplified temperature fluctuations over Greenland with limited ASM variability. In Phase II, a southerly-displaced jet suppressed transport of proximal monsoonal moisture, while the periodic sea-ice variability induced latitudinal oscillations in the jet stream. These oscillations repeatedly altered the dominant moisture sources, thereby generating rapid decadal- to centennial-scale ASM fluctuations. Thus, our results highlighted multi-stage hydroclimate variability within interstadials and provided new insights into the role of sea-air-ice interactions in regulating low-latitude climate.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113519"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886333","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}

{"title":"Spatial-temporal carbon isotope changes during the late Wuchiapingian to Early Triassic in South China and their global environmental implications","authors":"Yawen Cui ,&nbsp;Menghan Li ,&nbsp;Lilin Sun ,&nbsp;Dandan Li ,&nbsp;Guijie Zhang ,&nbsp;Xiaolin Zhang ,&nbsp;Yanan Shen","doi":"10.1016/j.palaeo.2025.113523","DOIUrl":"10.1016/j.palaeo.2025.113523","url":null,"abstract":"<div><div>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 (δ¹³C_carb) 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 δ¹³C_carb 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 δ¹³C_carb 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 δ¹³C_carb 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.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113523"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927944","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}

{"title":"Resource partitioning and modernization of arthropod feeding strategies on Pennsylvanian medullosalean foliage from the Nord-Pas-de-Calais Coalfield, France","authors":"Azucena Molina-Solís ,&nbsp;Christopher J. Cleal ,&nbsp;Artai A. Santos ,&nbsp;Stephen McLoughlin ,&nbsp;José B. Diez ,&nbsp;Borja Cascales-Miñana","doi":"10.1016/j.palaeo.2025.113517","DOIUrl":"10.1016/j.palaeo.2025.113517","url":null,"abstract":"<div><div>In recent years, there has been a dramatic increase in studies on plant-arthropod interactions in the fossil record. However, relatively few studies have targeted pre-Permian floras, which has hindered the reconstruction of trophic relationships in Carboniferous coal-forming ecosystems. Here, we document new evidence of arthropod and pathogen damage on Medullosales, which were prominent gymnosperm elements of Carboniferous coal forests, from the Nord-Pas-de-Calais Coalfield. We record 28 damage types (DTs) among 1206 fossil plant specimens belonging to <em>Alethopteris</em> and <em>Lonchopteris</em>. The damage categories are ascribed to seven functional feeding groups (FFGs): hole feeding (nine DTs), margin feeding (five DTs), surface feeding (three DTs), piercing and sucking (three DTs), oviposition (six DTs), galling (one DT), and pathogen attack (one DT). Rarefaction analyses evaluated sample completeness and clarified the damage incidence patterns. Our study provides the first quantitative assessment of herbivory from an Early–Middle Pennsylvanian terrestrial ecosystem. Although the proportion of damaged foliage is low (5.64% of specimens), its diversity is higher than in many younger (Late Pennsylvanian) floras. This suggests expansion and diversification of herbivore and pathogen attack at that time, which is consistent with the increased dominance of arborescent seed plants and the ascendancy of winged insects in the terrestrial fauna of the region. The presence of multiple feeding strategies on the studied medullosalean foliage indicates that this group of plants provided key food resources for diverse arthropod groups occupying the Nord-Pas-de-Calais palaeoforests. Almost all known types of FFGs are documented in the Nord-Pas-de-Calais fossil assemblages, suggesting that modern trophic relationships were likely established earlier than previously documented in Euramerican coal swamps.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113517"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145927939","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}

{"title":"Magnetic chronology of the late Miocene Wulangou red clay sequences in the northern Otindag Sandy Land","authors":"Hongyu Qi ,&nbsp;Yali Zhou ,&nbsp;Jiangli Pang ,&nbsp;Xiaoke Qiang ,&nbsp;Jiale Wang ,&nbsp;Baofeng Ma ,&nbsp;Tong Feng ,&nbsp;Xichen Li ,&nbsp;Yiting Zhao ,&nbsp;Yingying Cui ,&nbsp;Liping Jiang ,&nbsp;Siying Yue","doi":"10.1016/j.palaeo.2025.113521","DOIUrl":"10.1016/j.palaeo.2025.113521","url":null,"abstract":"&lt;div&gt;&lt;div&gt;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 &lt;sup&gt;40&lt;/sup&gt;Ar/&lt;sup&gt;39&lt;/sup&gt;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","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113521"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145872108","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}

{"title":"Late Holocene temperature changes in eastern North China reconstructed from branched glycerol dialkyl glycerol tetraethers (brGDGTs)","authors":"Hongyu Song ,&nbsp;Ying Wang ,&nbsp;Huaying Wang ,&nbsp;Can-Ge Li ,&nbsp;Yuecong Li ,&nbsp;Bing Li ,&nbsp;Yawen Ge ,&nbsp;Rongrong Wang ,&nbsp;Xiuyun Sun ,&nbsp;Ran Zhang ,&nbsp;Hanfei You ,&nbsp;Changhong Liu","doi":"10.1016/j.palaeo.2025.113530","DOIUrl":"10.1016/j.palaeo.2025.113530","url":null,"abstract":"<div><div>Temperature is the climatic factor with the most significant impact on human society. Studying temperature changes during the late Holocene is crucial for understanding climate change mechanisms and predicting future trends. We measured the branched glycerol dialkyl glycerol tetraethers (brGDGTs) in a sediment core (CFD-E) from the Caofeidian Wetland in eastern North China and used the record to quantitatively reconstruct temperature changes during the late Holocene. The results show that the average mean annual temperature (MAT) in the eastern part of North China (from ∼3440 cal. yr BP to the present) was 11 °C, comparable to the current regional MAT of 11.2 °C. Overall, the MAT showed a slight increasing trend, with amplitudes not exceeding 1 °C. We identified six cold events, at approximately 3.2 ka, 2.8 ka, 2.5 ka, 1.5 ka, the cooling episode during the Medieval Climate Anomaly (MCA), and the possible Little Ice Age (LIA), with cooling amplitudes exhibiting a gradually decreasing temporal trend. The 3.2 ka event had the largest cooling amplitude; however, the cooling amplitude of this event elsewhere in this inland region was relatively low. We propose that this discrepancy resulted from the combined effects of a weakened Kuroshio Current and Yellow Sea Warm Current, which amplified the 3.2 ka cooling event in coastal regions relative to inland areas. Additionally, the possible LIA in the study area exhibited a relatively low cooling magnitude. We hypothesize that enhanced greenhouse gas forcing, combined with a strengthened Kuroshio Current and Yellow Sea Warm Current, muted the cooling signal associated with the LIA in the study area. The cooling episode during the MCA may have been driven by the weakening of the Yellow Sea Warm Current, caused by the combined weakening of the Kuroshio Current and the East Asian Winter Monsoon.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113530"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145872112","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}

{"title":"A semi-quantitative ichnological approach to relative oxygen reconstruction: A case study over the Cenomanian-Turonian Oceanic Anoxic Event 2 in west-Central Alberta, Canada","authors":"Sara K. Biddle,&nbsp;Murray K. Gingras","doi":"10.1016/j.palaeo.2025.113539","DOIUrl":"10.1016/j.palaeo.2025.113539","url":null,"abstract":"<div><div>An exceptionally well-preserved organic-rich mudstone core from the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE2) interval in the Canadian Western Interior Seaway offers an excellent opportunity for comprehensive ichnological analysis of paleo‑oxygen fluctuations. Vertical trends in burrow size and diversity (i.e., Size-Diversity Index - SDI) have previously served as a proxy for relative oxygenation in low-oxygen stratigraphic settings. We note two factors that greatly impact oxygenation interpretations of SDI: (1) high bioturbation intensities or reworking dominantly by small (meiofaunal) animals lead to a large underestimation of ichnofossil diversity; and (2) paleoenvironmental stressors other than lowered oxygen levels (e.g., fluctuating salinity, reduced food availability, and rapid sedimentation). A semi-quantitative relative oxygen equation is proposed to account for these complexities and better proxy bottom water oxygenation over the interval. The equation combines diversity counts, burrow sizes, and bioturbation intensity (all indicators of high oxygenation), scaled with total organic carbon measurements (the presence of which is interpreted as an indicator of low oxygenation, corroborated by carbon isotope measurements over the interval). Integrating ichnological data with total organic carbon measurements accounts for the diminution and low diversity that may stem from a multitude of physicochemical factors. The results suggest that the bottom water oxygen fluctuated continuously and only very rarely, if at all, reached persistent anoxia. The proposed equation offers a repeatable approach to integrate ichnological and TOC data, providing a better ichnological-oxygen proxy for organic-rich mudstones.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113539"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886334","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}

{"title":"Dietary ecology of neotropical brocket deer: Evidence from mesowear and microwear analyses","authors":"María Fernanda Martínez-Polanco","doi":"10.1016/j.palaeo.2025.113542","DOIUrl":"10.1016/j.palaeo.2025.113542","url":null,"abstract":"<div><div>Neotropical deer exhibit remarkable diversity, particularly within the genus <em>Mazama</em>. Traditional species identification relied on morphological traits such as unbranched antlers; however, these features are now recognized as evolutionary convergences linked to similar environmental adaptations. Recent genetic analyses have reclassified <em>Mazama</em> into three genera—<em>Subulo</em> and <em>Passalites</em>—and reassigned one species to <em>Odocoileus</em>. Given the elusive nature of these small deer, this study investigates their dietary ecology through integrated dental wear analyses, specifically mesowear and microwear. A total of 357 specimens from eight cervid taxa—<em>Mazama americana</em>, <em>M. bricenii</em>, <em>M. nana</em>, <em>M. rufina</em>, <em>M. temama</em>, <em>Subulo gouazoubira</em>, <em>Odocoileus pandora</em>, and <em>Passalites nemorivagus</em>—were examined, spanning a broad geographic range from Mexico to Argentina. Mesowear analysis reveals a dietary gradient from strict leaf browsing in <em>O. pandora</em>, <em>M. bricenii</em>, and <em>M. nana</em> to more abrasive mixed feeding in <em>S. gouazoubira</em>, <em>M. americana</em>, and <em>P. nemorivagus</em>, with notable intraspecific variability in some taxa. Microwear patterns support these distinctions and highlight significant local dietary variation within species, despite overall stability in mesowear scores across countries. These findings demonstrate both ecological specialization and flexibility among Neotropical cervids and underscore the value of combined meso- and microwear approaches to reconstruct feeding strategies. This study provides essential baseline data for paleoecological and archaeological research, as well as for conservation studies of elusive brocket deer.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"685 ","pages":"Article 113542"},"PeriodicalIF":2.7,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928548","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}