Pub Date : 2025-02-15DOI: 10.1016/j.palaeo.2025.112810
Yang Yu, Xianyan Wang, Zhengchen Li, Qiang Su, Dongxu Cai, Haohan Wu, Huayu Lu
The evolution of the upper Yangtze River (UYR) is intricately tied to the developing topography shaped by the uplift of the southeastern Tibetan Plateau and the evolution of the Asian Monsoon. Diverse processes governing drainage evolution have given rise to varying perspectives on the formation age of the UYR. This study undertakes a comprehensive analysis, based on linear river-profile inversions of 43 catchments draining into the UYR, to reconstruct the spatial and temporal patterns of fluvial incision history as chronicled by river knickpoint migration. The results reveal that the initiation epochs of knickpoints migration in tributaries span from 10 Ma to 3 Ma, and exhibit a decreasing trend as one moves upstream along the main channel. The main knickpoint in the trunk, a consequence of intensified uplift in the southeastern Tibetan Plateau during the middle Miocene, migrated headward via a bottom-up integration process at a calculated rate of 118–274 km/Myr. This migratory knickpoint and headward erosion in the drainage played a pivotal role in integrating watersheds and expanding the UYR's influence onto the inner Tibetan Plateau, a process that was largely complete prior to the start of the Pliocene.
{"title":"Migrating incision wave and the bottom-up drainage integration of the upper Yangtze River on the Tibetan Plateau before Pliocene times","authors":"Yang Yu, Xianyan Wang, Zhengchen Li, Qiang Su, Dongxu Cai, Haohan Wu, Huayu Lu","doi":"10.1016/j.palaeo.2025.112810","DOIUrl":"10.1016/j.palaeo.2025.112810","url":null,"abstract":"<div><div>The evolution of the upper Yangtze River (UYR) is intricately tied to the developing topography shaped by the uplift of the southeastern Tibetan Plateau and the evolution of the Asian Monsoon. Diverse processes governing drainage evolution have given rise to varying perspectives on the formation age of the UYR. This study undertakes a comprehensive analysis, based on linear river-profile inversions of 43 catchments draining into the UYR, to reconstruct the spatial and temporal patterns of fluvial incision history as chronicled by river knickpoint migration. The results reveal that the initiation epochs of knickpoints migration in tributaries span from 10 Ma to 3 Ma, and exhibit a decreasing trend as one moves upstream along the main channel. The main knickpoint in the trunk, a consequence of intensified uplift in the southeastern Tibetan Plateau during the middle Miocene, migrated headward via a bottom-up integration process at a calculated rate of 118–274 km/Myr. This migratory knickpoint and headward erosion in the drainage played a pivotal role in integrating watersheds and expanding the UYR's influence onto the inner Tibetan Plateau, a process that was largely complete prior to the start of the Pliocene.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"665 ","pages":"Article 112810"},"PeriodicalIF":2.6,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143436676","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}
In this study, high–resolution detrital mineral analysis was conducted on sediments from a 70.20 m borehole (core CRE–1402) located on the Yangtze (Changjiang) Shoal, which is one of the largest sheets–like sand banks globally. The research aims to offer detailed insights into the provenance of the Yangtze Shoal, as well as the corresponding sedimentary processes linked to its formation. The findings reveal that the light mineral assemblages are primarily composed of plagioclase, lithics fragments, and quartz, while the heavy mineral assemblages are dominated by epidote, hornblende, and carbonate, followed by weathered mica, biotite, actinolite–tremolit, and ilmenite. The entire suite of detrital minerals of core CRE–1402 sediments closely resemble to the lower reaches of the Yangtze River and offshore areas of Yangtze River delta. The hornblende to epidote ratios (H/E) and garnet to epidote ratios (G/E) exhibit stable values throughout the core, indicating that the sediments in core CRE–1402 primarily originated from a single terrigenous source. The Quartz–Feldspar–Lithics (QFL) ternary plot of core CRE–1402 aligns closely to the ancient Yangtze River and the subaqueous Yangtze River delta, yet far from the subaqueous Yellow River delta. Core CRE–1402 sediments were derived from Yangtze River. The Yangtze River flowed through the study area during the low sea level period of Marine Isotope Stage (MIS) 6, and to other areas from MIS 5 to MIS 2. As sea level rose during early MIS 1, the river channel incised, and the estuary shifted southward along with the formation of coastal currents. During high sea levels, the Yangtze River estuary migrated south of the study area, leading to a lack of sedimentation in the region. The Yangtze River channel likely to pass by and supply sediments to the Yangtze shoal during sea level rise. This study provides valuable insights into the history of the Yangtze River channel and estuary since MIS 6, underscoring the river's significant role in shaping the sedimentary evolution of the western coast of the South Yellow Sea.
{"title":"Mineralogy of the Yangtze (Changjiang) shoal: Implications for provenance and land–sea interaction response to sea level changes since MIS 6","authors":"Junqiang Zhang , Jian Liu , Xin Zhang , Baojing Yue , Jiandong Qiu","doi":"10.1016/j.palaeo.2025.112813","DOIUrl":"10.1016/j.palaeo.2025.112813","url":null,"abstract":"<div><div>In this study, high–resolution detrital mineral analysis was conducted on sediments from a 70.20 m borehole (core CRE–1402) located on the Yangtze (Changjiang) Shoal, which is one of the largest sheets–like sand banks globally. The research aims to offer detailed insights into the provenance of the Yangtze Shoal, as well as the corresponding sedimentary processes linked to its formation. The findings reveal that the light mineral assemblages are primarily composed of plagioclase, lithics fragments, and quartz, while the heavy mineral assemblages are dominated by epidote, hornblende, and carbonate, followed by weathered mica, biotite, actinolite–tremolit, and ilmenite. The entire suite of detrital minerals of core CRE–1402 sediments closely resemble to the lower reaches of the Yangtze River and offshore areas of Yangtze River delta. The hornblende to epidote ratios (H/E) and garnet to epidote ratios (G/E) exhibit stable values throughout the core, indicating that the sediments in core CRE–1402 primarily originated from a single terrigenous source. The Quartz–Feldspar–Lithics (QFL) ternary plot of core CRE–1402 aligns closely to the ancient Yangtze River and the subaqueous Yangtze River delta, yet far from the subaqueous Yellow River delta. Core CRE–1402 sediments were derived from Yangtze River. The Yangtze River flowed through the study area during the low sea level period of Marine Isotope Stage (MIS) 6, and to other areas from MIS 5 to MIS 2. As sea level rose during early MIS 1, the river channel incised, and the estuary shifted southward along with the formation of coastal currents. During high sea levels, the Yangtze River estuary migrated south of the study area, leading to a lack of sedimentation in the region. The Yangtze River channel likely to pass by and supply sediments to the Yangtze shoal during sea level rise. This study provides valuable insights into the history of the Yangtze River channel and estuary since MIS 6, underscoring the river's significant role in shaping the sedimentary evolution of the western coast of the South Yellow Sea.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112813"},"PeriodicalIF":2.6,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430153","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 : 2025-02-12DOI: 10.1016/j.palaeo.2025.112811
A.M. Mancini , E. Nallino , F. Dela Pierre , R. Gennari , M. Natalicchio , G. Carnevale , G. Della Porta , A. Negri , F. Lozar
The pace and nature of paleoenvironmental dynamics leading to the Messinian Salinity Crisis (MSC) remain debated, with conflicting interpretations from the fossil and geochemical proxies.
This study focuses on two key sections in the Piedmont Basin (NW Italy), Pollenzo and Govone, representing the northernmost Mediterranean sector during the Messinian. By implementing the previously published calcareous nannofossil assemblages with new data and analyzing carbon and oxygen stable isotopes from benthic and planktic foraminifers, this research aims at understanding surface and bottom water conditions around the MSC onset (5.97 Ma).
In this gypsum-free part of the basin, calcareous nannofossil abundance remained stable for ∼40 kyrs into the MSC, before disappearing, likely due to taphonomic bias. Isotopic records from the benthic foraminifer Bolivina dilatata suggest variations in living depth, remineralization, temperature and isotopic composition of water. Oxygen isotope data from planktic foraminifer show little variation between the 6.83–6.79 Ma and 6.05–5.99 Ma intervals, suggesting only moderate salinity and/or temperature fluctuations between the different time intervals.
These findings interpreted in the light of previous records—including organic geochemistry, fish, pollen, and dinocyst fossils pointing to salinity fluctuations between normal marine to brackish—suggest that hypersaline conditions did not characterize the early phase of the MSC in this part of the basin. These insights challenge the traditional view of widespread hypersalinity during the MSC onset, highlighting the need to integrate multiple datasets to better understand the Messinian environments in the Mediterranean Basin.
{"title":"Surface and bottom water dynamics across the onset of the Messinian Salinity Crisis in the Piedmont Basin (NW Italy): Integrating micropaleontological and stable isotope evidence","authors":"A.M. Mancini , E. Nallino , F. Dela Pierre , R. Gennari , M. Natalicchio , G. Carnevale , G. Della Porta , A. Negri , F. Lozar","doi":"10.1016/j.palaeo.2025.112811","DOIUrl":"10.1016/j.palaeo.2025.112811","url":null,"abstract":"<div><div>The pace and nature of paleoenvironmental dynamics leading to the Messinian Salinity Crisis (MSC) remain debated, with conflicting interpretations from the fossil and geochemical proxies.</div><div>This study focuses on two key sections in the Piedmont Basin (NW Italy), Pollenzo and Govone, representing the northernmost Mediterranean sector during the Messinian. By implementing the previously published calcareous nannofossil assemblages with new data and analyzing carbon and oxygen stable isotopes from benthic and planktic foraminifers, this research aims at understanding surface and bottom water conditions around the MSC onset (5.97 Ma).</div><div>In this gypsum-free part of the basin, calcareous nannofossil abundance remained stable for ∼40 kyrs into the MSC, before disappearing, likely due to taphonomic bias. Isotopic records from the benthic foraminifer <em>Bolivina dilatata</em> suggest variations in living depth, remineralization, temperature and isotopic composition of water. Oxygen isotope data from planktic foraminifer show little variation between the 6.83–6.79 Ma and 6.05–5.99 Ma intervals, suggesting only moderate salinity and/or temperature fluctuations between the different time intervals.</div><div>These findings interpreted in the light of previous records—including organic geochemistry, fish, pollen, and dinocyst fossils pointing to salinity fluctuations between normal marine to brackish—suggest that hypersaline conditions did not characterize the early phase of the MSC in this part of the basin. These insights challenge the traditional view of widespread hypersalinity during the MSC onset, highlighting the need to integrate multiple datasets to better understand the Messinian environments in the Mediterranean Basin.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112811"},"PeriodicalIF":2.6,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420178","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 : 2025-02-11DOI: 10.1016/j.palaeo.2025.112809
Yuan Ling , Fangang Zeng , James Bendle , Jun Cheng , Long Zhang , Yong Wang , Lijun Tian
Hydroclimatic variations on the Tibetan Plateau since the Last Glacial Maximum (LGM) are still debated. Here, we reconstructed climatic and hydrological variability in the southwestern Tibetan Plateau since the LGM using climate proxies based on molecular distributions of n-alkanes, hydrogen (δD) and carbon (δ13C) isotopic compositions of terrestrial n-alkanes from sediments, and oxygen isotopic composition (δ18O) of authigenic carbonate at Lake Zabuye. The impact of climatic and environmental factors on these multiple proxies was discussed, and the TraCE-21 ka simulation was employed to facilitate a comprehensive model-data comparison. Our findings indicate that the δD of nC31 alkane in this lake was primarily influenced by temperature from the LGM to early deglaciation period, shifting to a predominance of precipitation influence from the Heinrich event 1 (H1) to the Holocene period. In contrast, the carbonate δ18O was found to be primarily governed by evaporative processes. Through comprehensive analysis of all proxies, we suggest that Lake Zabuye was dominated by the mid-latitude westerlies with cold and moist conditions from the LGM to early deglaciation. The H1 and Younger Dryas events were characterized by low temperatures and reduced precipitation due to the influence of the moderately intensified westerlies. The Indian summer monsoon (ISM) intensified during the Bølling/Allerød period, and its strength was comparable to that of the westerlies, resulting in plentiful rainfall and high evaporation. The ISM was dominant during the Holocene, characterized by abundant rainfall and high evaporation.
{"title":"Hydroclimatic evolution of the southwestern Tibetan Plateau since the last glacial maximum inferred from multi-proxy data in Lake Zabuye","authors":"Yuan Ling , Fangang Zeng , James Bendle , Jun Cheng , Long Zhang , Yong Wang , Lijun Tian","doi":"10.1016/j.palaeo.2025.112809","DOIUrl":"10.1016/j.palaeo.2025.112809","url":null,"abstract":"<div><div>Hydroclimatic variations on the Tibetan Plateau since the Last Glacial Maximum (LGM) are still debated. Here, we reconstructed climatic and hydrological variability in the southwestern Tibetan Plateau since the LGM using climate proxies based on molecular distributions of <em>n</em>-alkanes, hydrogen (δD) and carbon (δ<sup>13</sup>C) isotopic compositions of terrestrial <em>n</em>-alkanes from sediments, and oxygen isotopic composition (δ<sup>18</sup>O) of authigenic carbonate at Lake Zabuye. The impact of climatic and environmental factors on these multiple proxies was discussed, and the TraCE-21 ka simulation was employed to facilitate a comprehensive model-data comparison. Our findings indicate that the δD of <em>n</em>C<sub>31</sub> alkane in this lake was primarily influenced by temperature from the LGM to early deglaciation period, shifting to a predominance of precipitation influence from the Heinrich event 1 (H1) to the Holocene period. In contrast, the carbonate δ<sup>18</sup>O was found to be primarily governed by evaporative processes. Through comprehensive analysis of all proxies, we suggest that Lake Zabuye was dominated by the mid-latitude westerlies with cold and moist conditions from the LGM to early deglaciation. The H1 and Younger Dryas events were characterized by low temperatures and reduced precipitation due to the influence of the moderately intensified westerlies. The Indian summer monsoon (ISM) intensified during the Bølling/Allerød period, and its strength was comparable to that of the westerlies, resulting in plentiful rainfall and high evaporation. The ISM was dominant during the Holocene, characterized by abundant rainfall and high evaporation.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112809"},"PeriodicalIF":2.6,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420179","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 : 2025-02-11DOI: 10.1016/j.palaeo.2025.112807
George Pleș , Ioan I. Bucur , Emanoil Săsăran , Raluca Bindiu-Haitonic , Constantin Balica , Cristian Victor Mircescu , Dana Alina Magdaș , Adriana Vulpoi
A multi-tool investigation, including microfacies analysis, morphometric measurements, statistical analysis, SEM microscopy, biostratigraphy, and stable isotopes, was conducted on Lower Cretaceous oncoid-bearing carbonate beds that are well exposed in a limestone quarry in the Northern Apuseni Mountains, Romania. These carbonates are characterized by abundant bacinellid oncoids with thick cortices exhibiting a typical microfabric of micritic threads and spar-filled vesicles (bacinellid meshwork), that formed in a low-energy, inner-platform environment. The growth patterns of the bacinellid threads that form the meshwork of the oncoid cortices, such as constant thickness, branching modes, and bag-shaped/globular swellings, share close similarities with those developed by endolithic marine fungi. This, together with clotted micritic patches and frequent association with Lithocodium aggregatum sensu Elliott, 1956, suggests that these oncoid structures could have been generated by a microbial consortium involving bacteria, possibly fungi, and algae. Biostratigraphic and stable isotope data indicate that these bacinellid oncoid carbonates overlapped with the latest Aptian–earliest Albian Oceanic Anoxic Event 1b (OAE1b set/cluster). Our results on the bacinellid oncoid structures could support a possible relation between their extensive development and OAE1b, since bacteria, fungi, and other microbial communities are known to play an important role in carbon cycling and the restoration of oxygen levels in marine environments.
{"title":"Late Aptian–middle Albian bacinellid oncoid event, Apuseni Mountains, Romania: a possible link to OAE1b?","authors":"George Pleș , Ioan I. Bucur , Emanoil Săsăran , Raluca Bindiu-Haitonic , Constantin Balica , Cristian Victor Mircescu , Dana Alina Magdaș , Adriana Vulpoi","doi":"10.1016/j.palaeo.2025.112807","DOIUrl":"10.1016/j.palaeo.2025.112807","url":null,"abstract":"<div><div>A multi-tool investigation, including microfacies analysis, morphometric measurements, statistical analysis, SEM microscopy, biostratigraphy, and stable isotopes, was conducted on Lower Cretaceous oncoid-bearing carbonate beds that are well exposed in a limestone quarry in the Northern Apuseni Mountains, Romania. These carbonates are characterized by abundant bacinellid oncoids with thick cortices exhibiting a typical microfabric of micritic threads and spar-filled vesicles (bacinellid meshwork), that formed in a low-energy, inner-platform environment. The growth patterns of the bacinellid threads that form the meshwork of the oncoid cortices, such as constant thickness, branching modes, and bag-shaped/globular swellings, share close similarities with those developed by endolithic marine fungi. This, together with clotted micritic patches and frequent association with <em>Lithocodium aggregatum</em> sensu Elliott, 1956, suggests that these oncoid structures could have been generated by a microbial consortium involving bacteria, possibly fungi, and algae. Biostratigraphic and stable isotope data indicate that these bacinellid oncoid carbonates overlapped with the latest Aptian–earliest Albian Oceanic Anoxic Event 1b (OAE1b set/cluster). Our results on the bacinellid oncoid structures could support a possible relation between their extensive development and OAE1b, since bacteria, fungi, and other microbial communities are known to play an important role in carbon cycling and the restoration of oxygen levels in marine environments.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112807"},"PeriodicalIF":2.6,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430204","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 : 2025-02-10DOI: 10.1016/j.palaeo.2025.112805
Yinqiang Li , Kefu Yu , Lizeng Bian , Baoqing Hu , Zhiheng Liao , Shengmin Huang , Zhiguang Song , Weihua Liao
The evolution of Earth's climate is primarily reconstructed from deep-sea cores, while data from shallow-water carbonate successions play only a supplementary role. Furthermore, most available information originates from Western Europe, with limited data from the Middle East and almost none from the Americas and the Far East. While there has been significant discussion on the response of coralline algae to sea-level changes, their reactions to other paleoceanographic events and the long-term trends in their composition, abundance, and richness remain poorly understood. This study examines coralline algae in the carbonate rocks of Well CK2 in the northern South China Sea. A total of twelve genera, eight families, and three orders of coralline algae were identified in 666 petrologic thin sections. Coralline algal abundance was relatively high, between 10 and 4.28 Ma. In the early Miocene, coralline algal richness exhibited three distinct increases at 17.55 Ma, 17.45 Ma, and 17.44 Ma, corresponding to the Miocene Climate Optimum, likely as a response to global warming during this period. The distribution of Mesophyllum declined in response to a series of cooling events over the past 20 million years. Between 14.13 and 8.77 Ma, the concentration of Aethesolithon corresponded to a long-term sea-level fall, while its extinction indicated a rapid sea-level rise. At 6.71 Ma, the increasing abundance of Lithothamnion aligned with a rapid sea-level rise. A relative sea-level fall at 10 Ma was recorded by an increase in shallow-water coralline algae, which may be linked to regional uplift caused by the Dongsha movement. The algal distribution in the Xisha Islands reflects major geological and climatic events over the past 20 million years, underscoring the value of coralline algae as indicators of past climatic and environmental changes. These findings provide a new perspective on the late Cenozoic carbonate systems of the Far East.
{"title":"Dominance of coralline algae in the South China Sea: Insights into their responses to paleoceanographic events over the last 20 million years","authors":"Yinqiang Li , Kefu Yu , Lizeng Bian , Baoqing Hu , Zhiheng Liao , Shengmin Huang , Zhiguang Song , Weihua Liao","doi":"10.1016/j.palaeo.2025.112805","DOIUrl":"10.1016/j.palaeo.2025.112805","url":null,"abstract":"<div><div>The evolution of Earth's climate is primarily reconstructed from deep-sea cores, while data from shallow-water carbonate successions play only a supplementary role. Furthermore, most available information originates from Western Europe, with limited data from the Middle East and almost none from the Americas and the Far East. While there has been significant discussion on the response of coralline algae to sea-level changes, their reactions to other paleoceanographic events and the long-term trends in their composition, abundance, and richness remain poorly understood. This study examines coralline algae in the carbonate rocks of Well CK2 in the northern South China Sea. A total of twelve genera, eight families, and three orders of coralline algae were identified in 666 petrologic thin sections. Coralline algal abundance was relatively high, between 10 and 4.28 Ma. In the early Miocene, coralline algal richness exhibited three distinct increases at 17.55 Ma, 17.45 Ma, and 17.44 Ma, corresponding to the Miocene Climate Optimum, likely as a response to global warming during this period. The distribution of <em>Mesophyllum</em> declined in response to a series of cooling events over the past 20 million years. Between 14.13 and 8.77 Ma, the concentration of <em>Aethesolithon</em> corresponded to a long-term sea-level fall, while its extinction indicated a rapid sea-level rise. At 6.71 Ma, the increasing abundance of <em>Lithothamnion</em> aligned with a rapid sea-level rise. A relative sea-level fall at 10 Ma was recorded by an increase in shallow-water coralline algae, which may be linked to regional uplift caused by the Dongsha movement. The algal distribution in the Xisha Islands reflects major geological and climatic events over the past 20 million years, underscoring the value of coralline algae as indicators of past climatic and environmental changes. These findings provide a new perspective on the late Cenozoic carbonate systems of the Far East.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"663 ","pages":"Article 112805"},"PeriodicalIF":2.6,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387256","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 : 2025-02-07DOI: 10.1016/j.palaeo.2025.112789
Purushottam Adhikari , Gaurav Srivastava , Alexander Farnsworth , Harshita Bhatia , Sadanand , Sujata Poudel , Robert A. Spicer , Lalit K. Rai , Su Tao , Paul J. Valdes , Khum N. Paudayal
The South Asian Monsoon (SAM) is the strong summer monsoon within the Asian Monsoon System, driven by the thermal gradient between the warmer Asian landmass and the cooler Indian Ocean. High-resolution marine proxies indicate a decline in SAM strength after approximately 10 million years ago (Ma); however, terrestrial evidence has been limited. We present high-resolution and well-dated leaf assemblages from the Lower and Middle Siwalik of central Nepal, supported by paleoclimate modelling, which suggest a weakening of the SAM between 10.24 and 8.5 Ma. This decline is linked to a reduction in moisture supply, possibly due to a weakening of the Somali Jet. Our study highlights the potential of leaf physiognomy to reconstruct monsoon strength.
{"title":"Late Miocene weakening of the South Asian Monsoon: Insights from the Siwalik of Nepal","authors":"Purushottam Adhikari , Gaurav Srivastava , Alexander Farnsworth , Harshita Bhatia , Sadanand , Sujata Poudel , Robert A. Spicer , Lalit K. Rai , Su Tao , Paul J. Valdes , Khum N. Paudayal","doi":"10.1016/j.palaeo.2025.112789","DOIUrl":"10.1016/j.palaeo.2025.112789","url":null,"abstract":"<div><div>The South Asian Monsoon (SAM) is the strong summer monsoon within the Asian Monsoon System, driven by the thermal gradient between the warmer Asian landmass and the cooler Indian Ocean. High-resolution marine proxies indicate a decline in SAM strength after approximately 10 million years ago (Ma); however, terrestrial evidence has been limited. We present high-resolution and well-dated leaf assemblages from the Lower and Middle Siwalik of central Nepal, supported by paleoclimate modelling, which suggest a weakening of the SAM between 10.24 and 8.5 Ma. This decline is linked to a reduction in moisture supply, possibly due to a weakening of the Somali Jet. Our study highlights the potential of leaf physiognomy to reconstruct monsoon strength.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112789"},"PeriodicalIF":2.6,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420181","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 : 2025-02-07DOI: 10.1016/j.palaeo.2025.112806
Weihong He , Elizabeth A. Weldon , Kexin Zhang , Jianjun Bu , Tianyu Zhao , Yadong Xu , Chen Wu , Yafei Huang , Guitang Pan
The timing of the assembly of the Yangtze Block with the Cathaysia Block has been disputed for a long time. Tectonics partly controlled deposition and stratigraphy, and consequently observable changes in the lithologic features and sequences provide insights into the evolution of the paleogeographic and tectonic settings. This study analyzes stratigraphic sequences from the Neoproterozoic (from ca. 820 Ma or late Tonian) to the Cambrian from six areas/sites across the Yangtze and Cathaysia blocks, three from each block. The contrasts in the depositional features and stratigraphic sequences reveal that the paleogeographic settings were different in the two blocks. The Yangtze Block evolved from a rift basin to a carbonate platform whereas deposition occurred in a pelagic to hemipelagic setting in Cathaysia in the late Tonian to the Cambrian. During the Cryogenian, sediments typical of a glacial setting were commonly recorded in the Yangtze Block but were absent in Cathaysia. In the upper Tonian to the Cryogenian tuffaceous sediments were occasionally discovered in the Yangtze Block, but in Cathaysia, igneous rocks (from acidic to intermediate, and basic or even ultrabasic) were commonly found. These contrasts indicate that the Yangtze and Cathaysia blocks were separate, and located far apart, leading to differences in the depositional and climate settings. Also, the difference in magmatism records suggests that the Yangtze Block was situated along a passive continental margin, whereas Cathaysia was in an active tectonic setting (subduction of paleoocean) in the Tethys Tectonic Domain.
The records of spatio-temporal distribution of paleoocean-related remnants further infer that at least two basins of the Huanan Ocean (= South China Ocean) could have been developed in the late Tonian to the early Paleozoic, the Jiang-Shao oceanic basin probably subducted eastward, and the Zhenghe-Dabu oceanic basin subducted westward.
{"title":"Huanan Ocean remained active from Neoproterozoic to Cambrian: Evidence from stratigraphic sequences and paleoocean-related remnants in South China","authors":"Weihong He , Elizabeth A. Weldon , Kexin Zhang , Jianjun Bu , Tianyu Zhao , Yadong Xu , Chen Wu , Yafei Huang , Guitang Pan","doi":"10.1016/j.palaeo.2025.112806","DOIUrl":"10.1016/j.palaeo.2025.112806","url":null,"abstract":"<div><div>The timing of the assembly of the Yangtze Block with the Cathaysia Block has been disputed for a long time. Tectonics partly controlled deposition and stratigraphy, and consequently observable changes in the lithologic features and sequences provide insights into the evolution of the paleogeographic and tectonic settings. This study analyzes stratigraphic sequences from the Neoproterozoic (from ca. 820 Ma or late Tonian) to the Cambrian from six areas/sites across the Yangtze and Cathaysia blocks, three from each block. The contrasts in the depositional features and stratigraphic sequences reveal that the paleogeographic settings were different in the two blocks. The Yangtze Block evolved from a rift basin to a carbonate platform whereas deposition occurred in a pelagic to hemipelagic setting in Cathaysia in the late Tonian to the Cambrian. During the Cryogenian, sediments typical of a glacial setting were commonly recorded in the Yangtze Block but were absent in Cathaysia. In the upper Tonian to the Cryogenian tuffaceous sediments were occasionally discovered in the Yangtze Block, but in Cathaysia, igneous rocks (from acidic to intermediate, and basic or even ultrabasic) were commonly found. These contrasts indicate that the Yangtze and Cathaysia blocks were separate, and located far apart, leading to differences in the depositional and climate settings. Also, the difference in magmatism records suggests that the Yangtze Block was situated along a passive continental margin, whereas Cathaysia was in an active tectonic setting (subduction of paleoocean) in the Tethys Tectonic Domain.</div><div>The records of spatio-temporal distribution of paleoocean-related remnants further infer that at least two basins of the Huanan Ocean (= South China Ocean) could have been developed in the late Tonian to the early Paleozoic, the Jiang-Shao oceanic basin probably subducted eastward, and the Zhenghe-Dabu oceanic basin subducted westward.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112806"},"PeriodicalIF":2.6,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420180","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 : 2025-02-05DOI: 10.1016/j.palaeo.2025.112797
Yifeng Zhang , Shaopeng Zheng , Huajian Yao , Yonghang Xu , Liang Yi , Dongyi Li , Youquan Ye , Shanhu Liu , Yonggu Zhang , Lei Xue
The Taiwan Strait, connecting the East China Sea to the north and the South China Sea to the south, lies adjacent to the tectonically active Zhe-Min Uplift and the Taiwan Orogenic belt; however, its sedimentary history, such as geochronology, depositional processes, and controlling factors, remains largely unclear. This report presents an integrated study on a 160-m long sediment core (ZK01) retrieved from the southern Taiwan Strait, in terms of magnetostratigraphy, luminescence dating, and sediment grain-size and color. Our findings indicate that the basal age of core ZK01 was ∼4 Ma, with the Quaternary boundary at a depth of 108 m, and the boundary between the lower and middle Pleistocene (0.77 Ma) at 19 m. Prior to 1.07 Ma, the sediment accumulation rate was relatively stable, ranging from 34.4 to 43.3 m/Ma, suggesting a consistent depositional environment. Between 1.07 and 0.77 Ma, the rate increased to 98 m/Ma, likely linked to regional tectonic activity and climate variability during the Mid-Pleistocene Transition (MPT). Constrained by these geochronological results, sediment grain-size and color indices (L*, a*, and b*) were strongly influenced by sea-level fluctuations during the Plio-Pleistocene epoch, while neritic deposits in the southern Taiwan Strait after the MPT were thinner than those in the Yellow and Bohai Seas, likely resulted from local tectonic uplift.
{"title":"Sedimentary records of the southern Taiwan Strait since the late Pliocene and implications for sea-level and tectonic changes","authors":"Yifeng Zhang , Shaopeng Zheng , Huajian Yao , Yonghang Xu , Liang Yi , Dongyi Li , Youquan Ye , Shanhu Liu , Yonggu Zhang , Lei Xue","doi":"10.1016/j.palaeo.2025.112797","DOIUrl":"10.1016/j.palaeo.2025.112797","url":null,"abstract":"<div><div>The Taiwan Strait, connecting the East China Sea to the north and the South China Sea to the south, lies adjacent to the tectonically active Zhe-Min Uplift and the Taiwan Orogenic belt; however, its sedimentary history, such as geochronology, depositional processes, and controlling factors, remains largely unclear. This report presents an integrated study on a 160-m long sediment core (ZK01) retrieved from the southern Taiwan Strait, in terms of magnetostratigraphy, luminescence dating, and sediment grain-size and color. Our findings indicate that the basal age of core ZK01 was ∼4 Ma, with the Quaternary boundary at a depth of 108 m, and the boundary between the lower and middle Pleistocene (0.77 Ma) at 19 m. Prior to 1.07 Ma, the sediment accumulation rate was relatively stable, ranging from 34.4 to 43.3 m/Ma, suggesting a consistent depositional environment. Between 1.07 and 0.77 Ma, the rate increased to 98 m/Ma, likely linked to regional tectonic activity and climate variability during the Mid-Pleistocene Transition (MPT). Constrained by these geochronological results, sediment grain-size and color indices (L*, a*, and b*) were strongly influenced by sea-level fluctuations during the Plio-Pleistocene epoch, while neritic deposits in the southern Taiwan Strait after the MPT were thinner than those in the Yellow and Bohai Seas, likely resulted from local tectonic uplift.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"663 ","pages":"Article 112797"},"PeriodicalIF":2.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378439","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 : 2025-02-05DOI: 10.1016/j.palaeo.2025.112795
Giorgio Basilici , Juraj Janočko , Selma Simões de Castro , Paolo Lorenzoni , Paulo Roberto Oliveira da Silva , Áquila Ferreira Mesquita , Alexandre Ribeiro Cardoso , Alvaro Penteado Crósta , Carlos Roberto de Souza Filho , Dailto Silva , Daniele Cirillo , Taísa Rebuá Barroso , Adriana Mercedes Camejo Aviles , Frésia Soledad Ricardi Torres Branco
A Holocene sandy succession of Histosol, “lower interval deposits”, Spodosol and “upper interval deposits”, located at Serra do Espinhaço, SE Brazil, is interpreted as slope alluvium deposits, formed by unconfined water flows at the foot of hillslopes, near the sediment source area. This integrated study of macroscopic, micromorphological and geochemical features of this succession identifies the formative mechanisms that controlled the accumulation of the interbedded palaeosols and deposits.
The “lower interval deposits” and “upper interval deposits” represent the “construction” of a slope alluvium, i.e., the active sedimentation of material, previously weathered and stored on the adjacent bedrock areas, to form slope alluvium. The two palaeosols (Histosol - dated 8339–8049 cal yr BP; Spodosol – dated 1530–1404 cal yr BP) reflect the phase of “accumulation” and pedogenesis on the slope alluvium. The transition from the Histosol to “lower interval deposits” correlates with a sharp decrease of Araucaria forest likely driven by climate change. The transition from the Spodosol to “upper interval deposits” reflects anthropic fire-driven disruption of the original savannah vegetation. Dense vegetation cover promoted pedogenesis by sheltering deposits from erosion and enhancing intense weathering on the adjacent bedrock. Reductions in vegetation cover exposed weathered material on the bedrock, facilitating its erosion, transport and sedimentation on the slope alluvium.
Climatic or anthropogenic factors, which drove an increase and reduction in vegetation cover, appear to have been the primary variables controlling the development of slope alluvium successions in this Holocene inland cratonic area.
{"title":"Palaeosols interbedded with overland flood deposits in a Holocene slope alluvium succession, Serra do Pasmar, Southeast Brazil: Implications for palaeoclimate evolution and anthropogenic influences","authors":"Giorgio Basilici , Juraj Janočko , Selma Simões de Castro , Paolo Lorenzoni , Paulo Roberto Oliveira da Silva , Áquila Ferreira Mesquita , Alexandre Ribeiro Cardoso , Alvaro Penteado Crósta , Carlos Roberto de Souza Filho , Dailto Silva , Daniele Cirillo , Taísa Rebuá Barroso , Adriana Mercedes Camejo Aviles , Frésia Soledad Ricardi Torres Branco","doi":"10.1016/j.palaeo.2025.112795","DOIUrl":"10.1016/j.palaeo.2025.112795","url":null,"abstract":"<div><div>A Holocene sandy succession of Histosol, “lower interval deposits”, Spodosol and “upper interval deposits”, located at Serra do Espinhaço, SE Brazil, is interpreted as slope alluvium deposits, formed by unconfined water flows at the foot of hillslopes, near the sediment source area. This integrated study of macroscopic, micromorphological and geochemical features of this succession identifies the formative mechanisms that controlled the accumulation of the interbedded palaeosols and deposits.</div><div>The “lower interval deposits” and “upper interval deposits” represent the “construction” of a slope alluvium, i.e., the active sedimentation of material, previously weathered and stored on the adjacent bedrock areas, to form slope alluvium. The two palaeosols (Histosol - dated 8339–8049 cal yr BP; Spodosol – dated 1530–1404 cal yr BP) reflect the phase of “accumulation” and pedogenesis on the slope alluvium. The transition from the Histosol to “lower interval deposits” correlates with a sharp decrease of <em>Araucaria</em> forest likely driven by climate change. The transition from the Spodosol to “upper interval deposits” reflects anthropic fire-driven disruption of the original savannah vegetation. Dense vegetation cover promoted pedogenesis by sheltering deposits from erosion and enhancing intense weathering on the adjacent bedrock. Reductions in vegetation cover exposed weathered material on the bedrock, facilitating its erosion, transport and sedimentation on the slope alluvium.</div><div>Climatic or anthropogenic factors, which drove an increase and reduction in vegetation cover, appear to have been the primary variables controlling the development of slope alluvium successions in this Holocene inland cratonic area.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"663 ","pages":"Article 112795"},"PeriodicalIF":2.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349363","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}
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