Pub Date : 2024-11-09DOI: 10.1016/j.palaeo.2024.112583
Zhuo-Er Wang , Gui-Hua Chen , Rui Cao , Zhi-Hui Song , Zhao-Shuai Wang , Huai Wang , Su-Ting Ding , Jing-Yu Wu
Four fossil leaf assemblages from the Late Miocene to the early Late Pliocene of the Tengchong-Lianghe region, western Yunnan, China, are subjected to the Climate-Leaf Analysis Multivariate Program (CLAMP) and Leaf Margin Analysis (LMA) and compared with other late Neogene fossil flora from the southeastern margin of the Tibetan Plateau (SEMTP) and the eastern Himalayan foreland basins to reconstruct paleoclimate and capture ancient monsoon signature. The CLAMP-derived mean annual temperature (MAT) for the Late Neogene in Tengchong-Lianghe range from 17.9 ± 2.3 °C to 21.0 ± 2.3 °C, with the Early Pliocene being the warmest period, while the growing season precipitation (GSP) range from 1905 ± 481 mm to 2006 ± 481 mm with minimal change over time. The CLAMP and LMA results indicate a warmer and wetter climate in the late Neogene of the SEMTP and suggest that the paleoclimate in western Yunnan from the Late Miocene to early Late Pliocene was primarily influenced by global climate evolution rather than topographic changes. CLAMP results indicate that the modern pattern of the Asian Monsoon was established at least by the Late Miocene, though precipitation seasonality in the late Neogene of the SEMTP was weaker than today, likely attributed to the intensification of the East Asian Winter Monsoon driven by global cooling.
{"title":"Late Neogene monsoonal climate in the southeastern margin of the Tibetan Plateau revealed by leaf physiognomy evidence","authors":"Zhuo-Er Wang , Gui-Hua Chen , Rui Cao , Zhi-Hui Song , Zhao-Shuai Wang , Huai Wang , Su-Ting Ding , Jing-Yu Wu","doi":"10.1016/j.palaeo.2024.112583","DOIUrl":"10.1016/j.palaeo.2024.112583","url":null,"abstract":"<div><div>Four fossil leaf assemblages from the Late Miocene to the early Late Pliocene of the Tengchong-Lianghe region, western Yunnan, China, are subjected to the Climate-Leaf Analysis Multivariate Program (CLAMP) and Leaf Margin Analysis (LMA) and compared with other late Neogene fossil flora from the southeastern margin of the Tibetan Plateau (SEMTP) and the eastern Himalayan foreland basins to reconstruct paleoclimate and capture ancient monsoon signature. The CLAMP-derived mean annual temperature (MAT) for the Late Neogene in Tengchong-Lianghe range from 17.9 ± 2.3 °C to 21.0 ± 2.3 °C, with the Early Pliocene being the warmest period, while the growing season precipitation (GSP) range from 1905 ± 481 mm to 2006 ± 481 mm with minimal change over time. The CLAMP and LMA results indicate a warmer and wetter climate in the late Neogene of the SEMTP and suggest that the paleoclimate in western Yunnan from the Late Miocene to early Late Pliocene was primarily influenced by global climate evolution rather than topographic changes. CLAMP results indicate that the modern pattern of the Asian Monsoon was established at least by the Late Miocene, though precipitation seasonality in the late Neogene of the SEMTP was weaker than today, likely attributed to the intensification of the East Asian Winter Monsoon driven by global cooling.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112583"},"PeriodicalIF":2.6,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660869","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}
Pub Date : 2024-11-08DOI: 10.1016/j.palaeo.2024.112595
Nakhonekham Xaybouangeun , Zaw Zaw , Rao-Qiong Yang , Shankar Panthi , Dao-Xiong Gao , Viengsy Paothor , Ze-Xin Fan
The climate of Southeast Asia is influenced by the Asian monsoon systems, and inter-annual hydroclimate variability exerts a significant impact on forest ecosystems and agricultural productivity in this region. To improve our understanding of long-term drought variability, this study established ring-width chronologies for Pinus latteri trees at three sites in southern Laos. Site chronologies show negative correlations with temperature and positive correlations with precipitation, the self-calibrated Palmer Drought Severity Index (scPDSI), and the Standardized Precipitation-Evapotranspiration Index (SPEI) during the dry and wet months. The regional composite chronology shows the strongest correlation (r = 0.657, p < 0.001) with SPEI during March–August, indicating that the radial growth of P. latteri in southern Laos is primarily influenced by moisture conditions during the dry-to-wet season. A well-calibrated regression model was employed to reconstruct the variability of March–August SPEI for the period 1885–2019, explaining 43.1 % of the observed SPEI variance during the calibration period 1960–2019. The reconstruction records inter-annual to decadal-scale drought variability in southern Laos including eleven extreme dry years and seven extreme wet years. Notably, the frequency of extreme dry and wet events has increased since the 1970s. The reconstruction shows spectral peaks with periodicities of 2.3–3.1 years and displays negative correlations with sea surface temperatures (SSTs) in the tropical Pacific and Indian oceans, indicating that hydroclimatic variations in southern Laos are driven by large-scale ocean-atmospheric circulations.
{"title":"Reconstruction of hydroclimate variability in southern Laos from 1885 to 2019 based on Pinus latteri tree-ring data","authors":"Nakhonekham Xaybouangeun , Zaw Zaw , Rao-Qiong Yang , Shankar Panthi , Dao-Xiong Gao , Viengsy Paothor , Ze-Xin Fan","doi":"10.1016/j.palaeo.2024.112595","DOIUrl":"10.1016/j.palaeo.2024.112595","url":null,"abstract":"<div><div>The climate of Southeast Asia is influenced by the Asian monsoon systems, and inter-annual hydroclimate variability exerts a significant impact on forest ecosystems and agricultural productivity in this region. To improve our understanding of long-term drought variability, this study established ring-width chronologies for <em>Pinus latteri</em> trees at three sites in southern Laos. Site chronologies show negative correlations with temperature and positive correlations with precipitation, the self-calibrated Palmer Drought Severity Index (scPDSI), and the Standardized Precipitation-Evapotranspiration Index (SPEI) during the dry and wet months. The regional composite chronology shows the strongest correlation (<em>r</em> = 0.657, <em>p</em> < 0.001) with SPEI during March–August, indicating that the radial growth of <em>P. latteri</em> in southern Laos is primarily influenced by moisture conditions during the dry-to-wet season. A well-calibrated regression model was employed to reconstruct the variability of March–August SPEI for the period 1885–2019, explaining 43.1 % of the observed SPEI variance during the calibration period 1960–2019. The reconstruction records inter-annual to decadal-scale drought variability in southern Laos including eleven extreme dry years and seven extreme wet years. Notably, the frequency of extreme dry and wet events has increased since the 1970s. The reconstruction shows spectral peaks with periodicities of 2.3–3.1 years and displays negative correlations with sea surface temperatures (SSTs) in the tropical Pacific and Indian oceans, indicating that hydroclimatic variations in southern Laos are driven by large-scale ocean-atmospheric circulations.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112595"},"PeriodicalIF":2.6,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660906","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}
Pub Date : 2024-11-06DOI: 10.1016/j.palaeo.2024.112594
Jessie R.C. McCraw , Thomas S. Tobin , J. Kirk Cochran , Neil H. Landman
Ammonites are externally shelled cephalopods that were common in the North American Western Interior Seaway (WIS), and as they grew their aragonitic shells via accretion, they recorded aspects of their environment in the stable isotopic composition of their shells. While the mobility of ammonites may complicate efforts to reconstruct temperatures from their shells, they remain a potentially valuable target for paleothermometry. In this study, we reconstruct the spatial and temporal variability of WIS temperatures using a suite of ammonites (n = 113) spanning the last 25 million years of the Cretaceous along a North-South gradient ranging from the Canadian WIS to the Mississippi Embayment. We present a temporally high-resolution (∼0.6 Ma) oxygen isotope record from these ammonites that indicates cooling temperatures in the WIS of comparable magnitude (∼18 °C +/‐− 4°) to the temperature change seen in global studies, most notably cooling from the Cretaceous Thermal Maximum in the Turonian until the late Maastrichtian. Studies disagree regarding the development and strength of a latitudinal (pole-to-equator) temperature gradient during the Cretaceous; we do not see strong evidence for a latitudinal temperature gradient in the WIS. We do not observe any bias driven by ammonite morphology in our isotopic data, though we suggest that researchers consider the effects of taxonomy and ecological bias on their temperature records. As our ammonite δ18O record matches the direction and magnitude of global temperature reconstructions, our data imply that ammonites are viable targets for paleothermometry.
芒虫是北美西部内海航道（WIS）中常见的头足类外壳动物，当它们通过增殖长出文石质外壳时，其外壳的稳定同位素组成记录了它们所处环境的方方面面。虽然芒虫的流动性可能会使从其外壳重建温度的工作变得复杂，但它们仍然是古温度测定的潜在目标。在这项研究中，我们利用一套从加拿大WIS到密西西比河海湾的南北梯度上跨越白垩纪最后2500万年的棘皮动物（n = 113），重建了WIS温度的时空变异性。我们展示了这些氨虫的高时间分辨率（∼0.6 Ma）氧同位素记录，结果表明加拿大西印度洋地区的降温幅度（∼18 ° C +/-- 4°）与全球研究中看到的温度变化相当，其中最显著的是图伦纪白垩纪热极盛期至马斯特里赫特晚期的降温。关于白垩纪纬度（极点到赤道）温度梯度的发展和强度，研究结果存在分歧；我们没有发现 WIS 中存在纬度温度梯度的有力证据。虽然我们建议研究人员考虑分类和生态偏差对温度记录的影响，但我们在同位素数据中没有观察到任何由鹦鹉螺形态造成的偏差。由于我们的氨虫δ18O记录与全球温度重建的方向和幅度相吻合，我们的数据意味着氨虫是古温度测定的可行目标。
{"title":"Ammonites as paleothermometers: Isotopically reconstructed temperatures of the Western Interior Seaway track global records","authors":"Jessie R.C. McCraw , Thomas S. Tobin , J. Kirk Cochran , Neil H. Landman","doi":"10.1016/j.palaeo.2024.112594","DOIUrl":"10.1016/j.palaeo.2024.112594","url":null,"abstract":"<div><div>Ammonites are externally shelled cephalopods that were common in the North American Western Interior Seaway (WIS), and as they grew their aragonitic shells via accretion, they recorded aspects of their environment in the stable isotopic composition of their shells. While the mobility of ammonites may complicate efforts to reconstruct temperatures from their shells, they remain a potentially valuable target for paleothermometry. In this study, we reconstruct the spatial and temporal variability of WIS temperatures using a suite of ammonites (<em>n</em> = 113) spanning the last 25 million years of the Cretaceous along a North-South gradient ranging from the Canadian WIS to the Mississippi Embayment. We present a temporally high-resolution (∼0.6 Ma) oxygen isotope record from these ammonites that indicates cooling temperatures in the WIS of comparable magnitude (∼18 °C +/‐− 4°) to the temperature change seen in global studies, most notably cooling from the Cretaceous Thermal Maximum in the Turonian until the late Maastrichtian. Studies disagree regarding the development and strength of a latitudinal (pole-to-equator) temperature gradient during the Cretaceous; we do not see strong evidence for a latitudinal temperature gradient in the WIS. We do not observe any bias driven by ammonite morphology in our isotopic data, though we suggest that researchers consider the effects of taxonomy and ecological bias on their temperature records. As our ammonite δ<sup>18</sup>O record matches the direction and magnitude of global temperature reconstructions, our data imply that ammonites are viable targets for paleothermometry.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112594"},"PeriodicalIF":2.6,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660907","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}
Pub Date : 2024-11-05DOI: 10.1016/j.palaeo.2024.112584
Marisa Dusseault , Matthew Betts , Kristin M. Poduska , Meghan Burchell
Port Joli Harbour, situated on the southwest coast of the maritime province of Nova Scotia, Canada, has the highest density of shell midden deposits in Atlantic Canada. The terrestrial radiocarbon chronology points to continuous human occupation of the harbour from 1685 cal yr BP to 316 cal yr BP (2σ). Despite the abundance of the soft-shell clams Mya arenaria at shell midden sites throughout the harbour, they have not been incorporated into the chronology nor have they been used to study the local marine reservoir effect in the harbour. We report 12 new 14C measurements on archived Mya arenaria from the same depositional contexts as previously dated charcoal and terrestrial mammal bone samples from two shell middens in Port Joli Harbour. From these shell-charcoal and shell-bone pairs, we present preliminary calculations of local marine reservoir corrections (ΔR) for the harbour. The ΔR values are highly variable and are overall more positive than the pre-bomb values reported for the Scotian Shelf. The variability of these values highlights the challenges in calculating ΔR values from archived archaeological samples but also the opportunities to include high-resolution analysis of ΔR variations in discussions on human-environment interactions in coastal settings during the late Holocene. We suggest that the chondrophore may be more favourable for calculating first-order estimates of ΔR to be used in future archaeological calibrations, while high resolution analysis of the ventral margin region will be useful for climate reconstructions. We recommend that more 14C measurements from M. arenaria shells be obtained from either distinct features or rapidly deposited middens in Port Joli Harbour. A suite of temporally and geographically precise ΔR values for the harbour will not only allow for the study of middens that are at risk of coastal erosion and lack charcoal for 14C dating but will also allow for the reconstruction of past climate conditions and refine our understanding of late Holocene human-environment interactions in the North Atlantic.
{"title":"Preliminary investigation of the local marine reservoir effect in Port Joli Harbour, Nova Scotia using archaeological M. arenaria shells","authors":"Marisa Dusseault , Matthew Betts , Kristin M. Poduska , Meghan Burchell","doi":"10.1016/j.palaeo.2024.112584","DOIUrl":"10.1016/j.palaeo.2024.112584","url":null,"abstract":"<div><div>Port Joli Harbour, situated on the southwest coast of the maritime province of Nova Scotia, Canada, has the highest density of shell midden deposits in Atlantic Canada. The terrestrial radiocarbon chronology points to continuous human occupation of the harbour from 1685 cal yr BP to 316 cal yr BP (2σ). Despite the abundance of the soft-shell clams <em>Mya arenaria</em> at shell midden sites throughout the harbour, they have not been incorporated into the chronology nor have they been used to study the local marine reservoir effect in the harbour. We report 12 new <sup>14</sup>C measurements on archived <em>Mya arenaria</em> from the same depositional contexts as previously dated charcoal and terrestrial mammal bone samples from two shell middens in Port Joli Harbour. From these shell-charcoal and shell-bone pairs, we present preliminary calculations of local marine reservoir corrections (ΔR) for the harbour. The ΔR values are highly variable and are overall more positive than the pre-bomb values reported for the Scotian Shelf. The variability of these values highlights the challenges in calculating ΔR values from archived archaeological samples but also the opportunities to include high-resolution analysis of ΔR variations in discussions on human-environment interactions in coastal settings during the late Holocene. We suggest that the chondrophore may be more favourable for calculating first-order estimates of ΔR to be used in future archaeological calibrations, while high resolution analysis of the ventral margin region will be useful for climate reconstructions. We recommend that more <sup>14</sup>C measurements from <em>M. arenaria</em> shells be obtained from either distinct features or rapidly deposited middens in Port Joli Harbour. A suite of temporally and geographically precise ΔR values for the harbour will not only allow for the study of middens that are at risk of coastal erosion and lack charcoal for <sup>14</sup>C dating but will also allow for the reconstruction of past climate conditions and refine our understanding of late Holocene human-environment interactions in the North Atlantic.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"658 ","pages":"Article 112584"},"PeriodicalIF":2.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142723510","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}
Pub Date : 2024-11-04DOI: 10.1016/j.palaeo.2024.112581
Yanda Wang , Yunfei Huang , Haijun Song , Li Tian , Daoliang Chu , Jinnan Tong
The Permian-Triassic mass extinction was the largest extinction event in the Phanerozoic eon, with profound taxonomic and ecological effects on the ecosystem function. Functional diversity, a facet of biodiversity, could reflect the ecosystem function and stability. Although previous studies have shown that the functional richness of global marine organisms was decoupled from their taxonomic diversity during the mass extinctions, the evolution of functional diversity during the Permian-Triassic mass extinction and its aftermath is still under debate. The ecologically diverse clade bivalves may be more representative for understanding the evolution of functional diversity. To investigate the evolutionary dynamics of the functional diversity of bivalves, a global bivalve dataset of 8929 occurrences from the latest Permian to the Late Triassic was constructed. Functional richness, functional evenness, and functional redundancy were calculated to reflect the functional diversity in this study. Our results showed that the functional richness of bivalves was slightly affected by the Permian-Triassic mass extinction, decoupled from the significant decrease in taxonomic diversity. Meanwhile, a decrease in functional redundancy and an increase in functional evenness were observed after the mass extinction. In addition, bivalves showed high resilience to the mass extinction by maintaining the ecospace and reducing the functional redundancy. The high taxonomic diversity, high functional richness, high functional redundancy and relatively higher proportion of infaunal bivalves during the Late Triassic indicate that the Mesozoic marine revolution was already underway.
{"title":"Functional diversity and resilience of bivalves after the Permian-Triassic mass extinction","authors":"Yanda Wang , Yunfei Huang , Haijun Song , Li Tian , Daoliang Chu , Jinnan Tong","doi":"10.1016/j.palaeo.2024.112581","DOIUrl":"10.1016/j.palaeo.2024.112581","url":null,"abstract":"<div><div>The Permian-Triassic mass extinction was the largest extinction event in the Phanerozoic eon, with profound taxonomic and ecological effects on the ecosystem function. Functional diversity, a facet of biodiversity, could reflect the ecosystem function and stability. Although previous studies have shown that the functional richness of global marine organisms was decoupled from their taxonomic diversity during the mass extinctions, the evolution of functional diversity during the Permian-Triassic mass extinction and its aftermath is still under debate. The ecologically diverse clade bivalves may be more representative for understanding the evolution of functional diversity. To investigate the evolutionary dynamics of the functional diversity of bivalves, a global bivalve dataset of 8929 occurrences from the latest Permian to the Late Triassic was constructed. Functional richness, functional evenness, and functional redundancy were calculated to reflect the functional diversity in this study. Our results showed that the functional richness of bivalves was slightly affected by the Permian-Triassic mass extinction, decoupled from the significant decrease in taxonomic diversity. Meanwhile, a decrease in functional redundancy and an increase in functional evenness were observed after the mass extinction. In addition, bivalves showed high resilience to the mass extinction by maintaining the ecospace and reducing the functional redundancy. The high taxonomic diversity, high functional richness, high functional redundancy and relatively higher proportion of infaunal bivalves during the Late Triassic indicate that the Mesozoic marine revolution was already underway.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112581"},"PeriodicalIF":2.6,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586041","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}
Pub Date : 2024-11-03DOI: 10.1016/j.palaeo.2024.112582
Ana Laura S. Paiva , Pedro L. Godoy , Emma M. Dunne , Alexander Farnsworth , Paul J. Valdes , Daniel J. Lunt , Wilfried Klein , Max C. Langer , Annie S. Hsiou
Extant caimanines include the six modern species of caimans, which occur predominantly in South and Central America and are mostly medium-sized crocodylians. Nevertheless, the fossil record of the group reveals a significantly higher diversity, with remarkable body size variation. In particular, the giants Purussaurus and Mourasuchus, from the Miocene western Amazonian region, are two of the most prominent representatives. Previous work has demonstrated a correlation between the body size of crocodylians and abiotic factors throughout the Cenozoic; however, this relationship is poorly understood, particularly within the Caimaninae lineage. Here, we explore evolutionary body size patterns within Caimaninae, investigating the potential influence of climatic factors. Using a phylogenetically-informed method, we estimated the body size of 33 caimanine specimens, coupled with climatic variables from a General Circulation Model to reconstruct deep-time patterns. Our results indicate that giant Miocene caimanines are restricted to warmer conditions, with significantly less seasonal temperature variation. This suggests that the unmatching climatic conditions of the Miocene western Amazonian region possibly allowed the emergence of unique palaeoecosystems, favouring the sustenance of these very large crocodylians.
{"title":"The role of climate on the emergence of giant caimanines (Crocodylia, Alligatoroidea) from the Miocene western Amazonian region","authors":"Ana Laura S. Paiva , Pedro L. Godoy , Emma M. Dunne , Alexander Farnsworth , Paul J. Valdes , Daniel J. Lunt , Wilfried Klein , Max C. Langer , Annie S. Hsiou","doi":"10.1016/j.palaeo.2024.112582","DOIUrl":"10.1016/j.palaeo.2024.112582","url":null,"abstract":"<div><div>Extant caimanines include the six modern species of caimans, which occur predominantly in South and Central America and are mostly medium-sized crocodylians. Nevertheless, the fossil record of the group reveals a significantly higher diversity, with remarkable body size variation. In particular, the giants <em>Purussaurus</em> and <em>Mourasuchus</em>, from the Miocene western Amazonian region, are two of the most prominent representatives. Previous work has demonstrated a correlation between the body size of crocodylians and abiotic factors throughout the Cenozoic; however, this relationship is poorly understood, particularly within the Caimaninae lineage. Here, we explore evolutionary body size patterns within Caimaninae, investigating the potential influence of climatic factors. Using a phylogenetically-informed method, we estimated the body size of 33 caimanine specimens, coupled with climatic variables from a General Circulation Model to reconstruct deep-time patterns. Our results indicate that giant Miocene caimanines are restricted to warmer conditions, with significantly less seasonal temperature variation. This suggests that the unmatching climatic conditions of the Miocene western Amazonian region possibly allowed the emergence of unique palaeoecosystems, favouring the sustenance of these very large crocodylians.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112582"},"PeriodicalIF":2.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660868","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}
Pub Date : 2024-11-03DOI: 10.1016/j.palaeo.2024.112579
Mark W. Hounslow , Julian E. Andrews
Understanding the synchronicity of global climatic, environmental, and biotic events around the Norian-Rhaetian boundary (NRB) is problematic because of major international differences in biochronology. We instead use magnetostratigraphic and global carbon isotopic changes to produce more precise global correlation. This work focusses on the base and top of the Rhaetian, with principal age control from a new late Norian to latest Rhaetian magnetostratigraphy from Lavernock (southern Wales) which can be directly correlated to the proposed NRB sections at Pignola Abriola (Italy) and Steinbergkogel (Austria). A disconformity exists in the Lavernock section in its late Norian part (Branscombe Mudstone Formation), but the NRB interval is largely complete. The magnetostratigraphy and a composite δ13Corg stratigraphy from three British sections, demonstrate synchronous changes in both terrestrial and marine records. This analysis indicates the older proposed definition of the NRB from Steinbergkogel is in the upper few metres of the Branscombe Mudstone Formation, while the younger NRB definition from Pignola Abriola is in the upper parts of the Blue Anchor Formation. The latest Rhaetian magnetostratigraphy from Lavernock records reverse magnetochrons UT26r and UT28r which closely pre-date and post-date the widely recognised Marshi and Spelae carbon isotope excursions, respectively. Magnetochrons UT28r and UT27r were previously recognised at St Audrie's Bay (SW England), with relationships to the Newark Supergroup which tightly constrain the first phase of CAMP eruptions to overlap the Spelae excursion. The carbon isotope excursions present in the Blue Anchor Formation lacustrine successions, demonstrate the likely atmospheric, and global spread of these perturbations.
{"title":"Improved chronostratigraphy and fine-tuned timing for Late Triassic palaeoenvironmental changes in SW Britain using coupled magnetic polarity and carbon isotope stratigraphy","authors":"Mark W. Hounslow , Julian E. Andrews","doi":"10.1016/j.palaeo.2024.112579","DOIUrl":"10.1016/j.palaeo.2024.112579","url":null,"abstract":"<div><div>Understanding the synchronicity of global climatic, environmental, and biotic events around the Norian-Rhaetian boundary (NRB) is problematic because of major international differences in biochronology. We instead use magnetostratigraphic and global carbon isotopic changes to produce more precise global correlation. This work focusses on the base and top of the Rhaetian, with principal age control from a new late Norian to latest Rhaetian magnetostratigraphy from Lavernock (southern Wales) which can be directly correlated to the proposed NRB sections at Pignola Abriola (Italy) and Steinbergkogel (Austria). A disconformity exists in the Lavernock section in its late Norian part (Branscombe Mudstone Formation), but the NRB interval is largely complete. The magnetostratigraphy and a composite δ<sup>13</sup>C<sub>org</sub> stratigraphy from three British sections, demonstrate synchronous changes in both terrestrial and marine records. This analysis indicates the older proposed definition of the NRB from Steinbergkogel is in the upper few metres of the Branscombe Mudstone Formation, while the younger NRB definition from Pignola Abriola is in the upper parts of the Blue Anchor Formation. The latest Rhaetian magnetostratigraphy from Lavernock records reverse magnetochrons UT26r and UT28r which closely pre-date and post-date the widely recognised Marshi and Spelae carbon isotope excursions, respectively. Magnetochrons UT28r and UT27r were previously recognised at St Audrie's Bay (SW England), with relationships to the Newark Supergroup which tightly constrain the first phase of CAMP eruptions to overlap the Spelae excursion. The carbon isotope excursions present in the Blue Anchor Formation lacustrine successions, demonstrate the likely atmospheric, and global spread of these perturbations.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112579"},"PeriodicalIF":2.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-03DOI: 10.1016/j.palaeo.2024.112573
Shengxian Zhu , Xianguo Lang , Kun Zhao , Chaochao Xing , Mingcai Hou
The Cryogenian Sturtian glaciation (717–660 Ma) represents the most extreme icehouse climate condition in Earth's history, during which the global ocean was completely frozen, known as the Snowball Earth event. It is widely accepted that such a global freeze could result in persistent anoxic and ferruginous marine conditions. Here, we report on a Sturtian-aged storm-prone shelf (ca. 678 Ma) in South China, characterized by dynamic fluctuations in marine redox conditions. We observe a sequence of transitions from euxinic (anoxic and H2S-enriched) to ferruginous (anoxic but iron-rich), and finally to oxic conditions on this shelf. The euxinic deposits frequently exhibit hummocky/swaley cross-bedding structures (HCS/SCS) and contain high levels of authigenic francolite. In contrast, the ferruginous interval displays rare occurrences of HCS/SCS and lower amounts of authigenic francolite. Conversely, the oxic deposits show no evidence of storm activity. These results suggest that the strong storm waves played a crucial role in facilitating the upwelling of phosphorus-enriched deep water, thereby creating favorable nutrient conditions that stimulated primary productivity and microbial sulfate reduction (MSR). These findings underscore the significant influence of local meteorological conditions, particularly storm activity, on marine redox changes. Furthermore, dynamic storm-induced currents combined with marine redox conditions indicate the presence of an unfrozen sea with active biogeochemical cycles during the Cryogenian Sturtian glaciation. This study confirms the complex interactions among meteorology, oceanography, and Earth's climate system during extreme glacial events.
{"title":"Meteorological influences on marine chemistry during the Cryogenian Sturtian glaciation","authors":"Shengxian Zhu , Xianguo Lang , Kun Zhao , Chaochao Xing , Mingcai Hou","doi":"10.1016/j.palaeo.2024.112573","DOIUrl":"10.1016/j.palaeo.2024.112573","url":null,"abstract":"<div><div>The Cryogenian Sturtian glaciation (717–660 Ma) represents the most extreme icehouse climate condition in Earth's history, during which the global ocean was completely frozen, known as the Snowball Earth event. It is widely accepted that such a global freeze could result in persistent anoxic and ferruginous marine conditions. Here, we report on a Sturtian-aged storm-prone shelf (ca. 678 Ma) in South China, characterized by dynamic fluctuations in marine redox conditions. We observe a sequence of transitions from euxinic (anoxic and H<sub>2</sub>S-enriched) to ferruginous (anoxic but iron-rich), and finally to oxic conditions on this shelf. The euxinic deposits frequently exhibit hummocky/swaley cross-bedding structures (HCS/SCS) and contain high levels of authigenic francolite. In contrast, the ferruginous interval displays rare occurrences of HCS/SCS and lower amounts of authigenic francolite. Conversely, the oxic deposits show no evidence of storm activity. These results suggest that the strong storm waves played a crucial role in facilitating the upwelling of phosphorus-enriched deep water, thereby creating favorable nutrient conditions that stimulated primary productivity and microbial sulfate reduction (MSR). These findings underscore the significant influence of local meteorological conditions, particularly storm activity, on marine redox changes. Furthermore, dynamic storm-induced currents combined with marine redox conditions indicate the presence of an unfrozen sea with active biogeochemical cycles during the Cryogenian Sturtian glaciation. This study confirms the complex interactions among meteorology, oceanography, and Earth's climate system during extreme glacial events.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112573"},"PeriodicalIF":2.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586040","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}
Pub Date : 2024-11-03DOI: 10.1016/j.palaeo.2024.112578
Giulia Amaglio , Maria Rose Petrizzo , Erik Wolfgring , Ann Holbourn , Wolfgang Kuhnt
The Oceanic Anoxic Event 2 (OAE 2), across the Cenomanian-Turonian boundary interval, was characterized by global environmental perturbations in the carbon cycle that affected the abundance and biodiversity of marine biota and their paleoecological preferences. International Ocean Discovery Program (IODP) Sites U1513 and U1516 in the Mentelle Basin (offshore SW Australia) reveal a continuous foraminiferal record that document the adaptative response of biota, suitable to reconstruct paleoenvironmental conditions in the water column and at the seafloor. Below and during the initial part of the OAE 2, we do not observe changes in the benthic foraminiferal assemblages dominated by Gavelinella, Gyroidinoides and Stensioeina. Agglutinated foraminifera are rare, whereas Microhedbergella and Muricohedbergella dominate the planktonic foraminiferal assemblage, indicating possible eutrophication episodes below and during the OAE 2 associated to an increase in terrigenous sediments. However, a positive peak in Zr/Rb ratios, the unique occurrence of Stensioeina truncata, and the increase in epifaunal- infaunal ratio, particularly at Site U1516, indicate a greater eolian transportation of sediments and an enhanced oxygenation at the seafloor, which might be related to the identification of the Plenus Cold Event (PCE) at high latitudes. An interval of low CaCO3 content within the peak of OAE 2 is characterized by the absence of foraminifera and dominance of siliceous organisms. It is also marked by a sudden enhancement of the hydrological cycle, probably causing a shoaling of the Calcite Compensation Depth (CCD). However, Site U1516 shows few samples with a change in the planktonic and benthic foraminiferal assemblage.
Above this interval, both sites are characterized by a different benthic foraminiferal assemblage with the occurrence of Conorboides claytonensis in the uppermost part of OAE 2. At Site U1513, epi-infaunal ratio increase, planktonic foraminifera show the highest diversification, rainfall decreases, indicating a recovery towards a well-stratified water column with mesotrophic regimes and a drier environment, whereas Site U1516 shows a slower recovery.
{"title":"Paleoceanographic changes across OAE 2 inferred from resilient foraminifera and XRF data at southern high latitudes (IODP Sites U1513 and U1516, Mentelle Basin, SW Australia)","authors":"Giulia Amaglio , Maria Rose Petrizzo , Erik Wolfgring , Ann Holbourn , Wolfgang Kuhnt","doi":"10.1016/j.palaeo.2024.112578","DOIUrl":"10.1016/j.palaeo.2024.112578","url":null,"abstract":"<div><div>The Oceanic Anoxic Event 2 (OAE 2), across the Cenomanian-Turonian boundary interval, was characterized by global environmental perturbations in the carbon cycle that affected the abundance and biodiversity of marine biota and their paleoecological preferences. International Ocean Discovery Program (IODP) Sites U1513 and U1516 in the Mentelle Basin (offshore SW Australia) reveal a continuous foraminiferal record that document the adaptative response of biota, suitable to reconstruct paleoenvironmental conditions in the water column and at the seafloor. Below and during the initial part of the OAE 2, we do not observe changes in the benthic foraminiferal assemblages dominated by <em>Gavelinella</em>, <em>Gyroidinoides</em> and <em>Stensioeina</em>. Agglutinated foraminifera are rare, whereas <em>Microhedbergella</em> and <em>Muricohedbergella</em> dominate the planktonic foraminiferal assemblage, indicating possible eutrophication episodes below and during the OAE 2 associated to an increase in terrigenous sediments. However, a positive peak in Zr/Rb ratios, the unique occurrence of <em>Stensioeina truncata,</em> and the increase in epifaunal- infaunal ratio, particularly at Site U1516, indicate a greater eolian transportation of sediments and an enhanced oxygenation at the seafloor, which might be related to the identification of the Plenus Cold Event (PCE) at high latitudes. An interval of low CaCO<sub>3</sub> content within the peak of OAE 2 is characterized by the absence of foraminifera and dominance of siliceous organisms. It is also marked by a sudden enhancement of the hydrological cycle, probably causing a shoaling of the Calcite Compensation Depth (CCD). However, Site U1516 shows few samples with a change in the planktonic and benthic foraminiferal assemblage.</div><div>Above this interval, both sites are characterized by a different benthic foraminiferal assemblage with the occurrence of <em>Conorboides claytonensis</em> in the uppermost part of OAE 2. At Site U1513, epi-infaunal ratio increase, planktonic foraminifera show the highest diversification, rainfall decreases, indicating a recovery towards a well-stratified water column with mesotrophic regimes and a drier environment, whereas Site U1516 shows a slower recovery.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"657 ","pages":"Article 112578"},"PeriodicalIF":2.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-02DOI: 10.1016/j.palaeo.2024.112580
Carlo Corradini , Maria G. Corriga , Monica Pondrelli , Amalia Spina , Thomas J. Suttner
In the late Lochkovian a regression is documented in several areas of the world, followed by a transgression in the early Pragian. Connected with the eustatic variation, a minor extinction event occurred (“Lochkovian-Pragian Event”), affecting several fossil groups, a strong reduction of carbonate production and sedimentary facies changes. The Carnic Alps are a key area for studying this event, because Lower Devonian rocks are widely exposed, representing diverse sedimentary environments from shallow water to relatively deep shelf. Fourteen sections were measured along the Carnic Alps across the Lochkovian-Pragian boundary. In the shallower part of the basin, both the Polinik and the Seekopf formations span the boundary, but evident erosional surfaces are observable in the field at the Lochkovian-Pragian boundary. Above the unconformity, at places the so-called megaclast horizon is present in the Seekopf Formation. In intermediate settings the Rauchkofel Fm. is unconfomably followed by the Kellerwand Fm., and different parts of the upper Lochkovian and lower Pragian are missing in the various sections. In the deeper parts of the basin the transition from the La Valute Fm. to the Findenig Fm. is slightly diachronous from the latest Lochkovian to the earliest Pragian; however, conodonts and tentaculitids are rare in the marly boundary beds, preventing a precise chronostratigraphic calibration of these levels. At places, evidence of subaerial exposure at the formational boundary is documented. In general, the hiatus seems to be larger in the western part of the Carnic Alps, in correspondence with the shallower parts of the succession, suggesting a sea level drop in the late Lochkovian, followed by a transgression in the Pragian. Data from the Carnic Alps are compared with those of other regions of North Gondwana to demonstrate that the sea-level variation at the Lochkovian-Pragian boundary are of global importance
{"title":"The “Lochkovian-Pragian Event” re-assessed: New data from the low latitude shelf of peri-Gondwana","authors":"Carlo Corradini , Maria G. Corriga , Monica Pondrelli , Amalia Spina , Thomas J. Suttner","doi":"10.1016/j.palaeo.2024.112580","DOIUrl":"10.1016/j.palaeo.2024.112580","url":null,"abstract":"<div><div>In the late Lochkovian a regression is documented in several areas of the world, followed by a transgression in the early Pragian. Connected with the eustatic variation, a minor extinction event occurred (“Lochkovian-Pragian Event”), affecting several fossil groups, a strong reduction of carbonate production and sedimentary facies changes. The Carnic Alps are a key area for studying this event, because Lower Devonian rocks are widely exposed, representing diverse sedimentary environments from shallow water to relatively deep shelf. Fourteen sections were measured along the Carnic Alps across the Lochkovian-Pragian boundary. In the shallower part of the basin, both the Polinik and the Seekopf formations span the boundary, but evident erosional surfaces are observable in the field at the Lochkovian-Pragian boundary. Above the unconformity, at places the so-called megaclast horizon is present in the Seekopf Formation. In intermediate settings the Rauchkofel Fm. is unconfomably followed by the Kellerwand Fm., and different parts of the upper Lochkovian and lower Pragian are missing in the various sections. In the deeper parts of the basin the transition from the La Valute Fm. to the Findenig Fm. is slightly diachronous from the latest Lochkovian to the earliest Pragian; however, conodonts and tentaculitids are rare in the marly boundary beds, preventing a precise chronostratigraphic calibration of these levels. At places, evidence of subaerial exposure at the formational boundary is documented. In general, the hiatus seems to be larger in the western part of the Carnic Alps, in correspondence with the shallower parts of the succession, suggesting a sea level drop in the late Lochkovian, followed by a transgression in the Pragian. Data from the Carnic Alps are compared with those of other regions of North Gondwana to demonstrate that the sea-level variation at the Lochkovian-Pragian boundary are of global importance</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"656 ","pages":"Article 112580"},"PeriodicalIF":2.6,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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