Pub Date : 2023-04-20DOI: 10.1177/09596836231163492
Pujarini Samal, Saradambal Ramchandaran Subramanian, J. Srivastava, M. Kawsar, Madhusudanan Chandrika Manoj, G. P. Gurumurthy, Mohd Munazir Chauhan, Sajid Ali, Mahboob Alam, Anupam Sharma, P. S. Jena, A. Shivam, R. Bhushan
Understanding the impact of climate change on the vegetation cover in the past is crucial for predicting the future warming scenario and its consequences. The present study integrates biotic (palynological analysis) and abiotic proxy (sediment chemistry, clay mineral assemblages and grain size end member (EM) analysis) records in a chronologically constrained sedimentary sequence from the southeastern part of the Mahanadi River delta to reconstruct the hydroclimate since 2600 years. The Mahanadi delta sediments are primarily derived from felsic rock source possibly composed of granites or granulites. The dominance of herbaceous taxa, high aridity index and deposition of fine grain (EM1) sediment possibly suggest a relatively cold and dry climate in the study region during ~2600–2100 cal yr BP corresponding to the Iron Age Cold Period (IACP). Presence of diverse mangrove and tree taxa, deposition of coarser sediment (EM3) and relatively high abundance of secondary clay minerals possibly indicate high precipitation associated with the Roman Warm Period (RWP, ~2100–1800 cal yr BP). A decline in mangroves, dominance of herbaceous taxa and high deposition of fine grain (EM2) sediment from ~1800 to 1300 cal yr BP may indicate a relatively drier climate coinciding with the Dark Age Cold Period (DACP). High moisture index and an increased value of Rb/Sr during ~1300 cal yr BP may suggest a wet phase with the onset of the Medieval Climatic Anomaly (MCA) and later shifted to an arid climate during ~1100–800 cal yr BP. After ~800 cal yr BP, a sharp decline in all weathering indices and vegetation cover, dominance of illite indicates a relatively dry climate which could mark the Little Ice Age (LIA, ~800–300 cal yr BP). A small increase in the terrestrial flux, as well as the weathering indices after ~300 cal yr BP, may suggest the onset of recent warming.
了解过去气候变化对植被覆盖的影响对于预测未来变暖情景及其后果至关重要。本研究整合了Mahanadi河三角洲东南部一个受时间限制的沉积序列中的生物（孢粉学分析）和非生物代理（沉积物化学、粘土矿物组合和粒径末端成员（EM）分析）记录，以重建2600年以来的水气候。Mahanadi三角洲沉积物主要来源于长英质岩石，可能由花岗岩或麻粒岩组成。草本类群的优势、高干旱指数和细粒（EM1）沉积物的沉积可能表明，在相当于铁器时代寒冷期（IACP）的约2600–2100 cal yr BP期间，研究区域的气候相对寒冷和干燥。不同红树林和树木分类群的存在、较粗沉积物（EM3）的沉积和相对高丰度的次生粘土矿物可能表明与罗马暖期有关的高降水量（RWP，~2100–1800卡年BP）。红树林的减少、草本类群的优势和细粒（EM2）沉积物的高沉积量（约1800至1300卡年BP）可能表明气候相对干燥，与黑暗时代寒冷期（DACP）相吻合。在约1300 cal yr BP期间，高湿度指数和Rb/Sr值的增加可能表明随着中世纪气候异常（MCA）的开始，处于潮湿阶段，随后在约1100–800 cal yr的BP期间转变为干旱气候。在~800 cal yr BP之后，所有风化指数和植被覆盖率急剧下降，伊利石占主导地位，表明气候相对干燥，这可能标志着小冰期（LIA，~800–300 cal yr BP）。陆地通量的小幅增加，以及约300卡年BP后的风化指数，可能表明近期变暖的开始。
{"title":"A 2600-yr multiproxy record for climate and vegetation reconstruction along the Mahanadi River delta, east coast of India","authors":"Pujarini Samal, Saradambal Ramchandaran Subramanian, J. Srivastava, M. Kawsar, Madhusudanan Chandrika Manoj, G. P. Gurumurthy, Mohd Munazir Chauhan, Sajid Ali, Mahboob Alam, Anupam Sharma, P. S. Jena, A. Shivam, R. Bhushan","doi":"10.1177/09596836231163492","DOIUrl":"https://doi.org/10.1177/09596836231163492","url":null,"abstract":"Understanding the impact of climate change on the vegetation cover in the past is crucial for predicting the future warming scenario and its consequences. The present study integrates biotic (palynological analysis) and abiotic proxy (sediment chemistry, clay mineral assemblages and grain size end member (EM) analysis) records in a chronologically constrained sedimentary sequence from the southeastern part of the Mahanadi River delta to reconstruct the hydroclimate since 2600 years. The Mahanadi delta sediments are primarily derived from felsic rock source possibly composed of granites or granulites. The dominance of herbaceous taxa, high aridity index and deposition of fine grain (EM1) sediment possibly suggest a relatively cold and dry climate in the study region during ~2600–2100 cal yr BP corresponding to the Iron Age Cold Period (IACP). Presence of diverse mangrove and tree taxa, deposition of coarser sediment (EM3) and relatively high abundance of secondary clay minerals possibly indicate high precipitation associated with the Roman Warm Period (RWP, ~2100–1800 cal yr BP). A decline in mangroves, dominance of herbaceous taxa and high deposition of fine grain (EM2) sediment from ~1800 to 1300 cal yr BP may indicate a relatively drier climate coinciding with the Dark Age Cold Period (DACP). High moisture index and an increased value of Rb/Sr during ~1300 cal yr BP may suggest a wet phase with the onset of the Medieval Climatic Anomaly (MCA) and later shifted to an arid climate during ~1100–800 cal yr BP. After ~800 cal yr BP, a sharp decline in all weathering indices and vegetation cover, dominance of illite indicates a relatively dry climate which could mark the Little Ice Age (LIA, ~800–300 cal yr BP). A small increase in the terrestrial flux, as well as the weathering indices after ~300 cal yr BP, may suggest the onset of recent warming.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41417245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-18DOI: 10.1177/09596836231163510
M. Lopes, O. Aguilera, C. Monteiro-Neto, N. Miller, M. D. Gaspar, M. R. Costa
In this study, laser ablation–inductively coupled plasma–mass spectrometry was used to characterize the growth patterns of otolith of Micropogonias furnieri from southeastern Brazil under the influence of coastal marine upwelling. Archaeological fish sagittae otoliths of M. furnieri recovered from Brazilian shell mounds (5820‒4980 cal BP) were analysed and compared with those of modern specimens. Otolith Sr/Ca analysis indicated that off southeastern Brazil, M. furnieri shifted from freshwater/brackish in archaeological specimens to brackish/marine in modern times. Regular core-to-edge Sr/Ca oscillations suggest that both modern and archaeological M. furnieri are resident estuarine fish that also use the marine waters adjacent to the coastal zone. Based on analyses of a wide range of otolith edge Sr/Ca values measured in archaeological samples, pre-colonial fishing activities in the coastal regions of Guanabara Bay occurred throughout the year. This study reinforces the importance of M. furnieri as a precolonial fishing resource in this area and demonstrates a shift in fishing practices, where smaller fish are targetted within the bay and larger fish are caught beyond the bay. These data may also be indicative of a shift in the life cycle of this species, possibly caused by the overfishing of this important resource and significant increase in human activities in protected coastal waters in modern times.
{"title":"Archaeological and modern whitemouth croaker fish (Micropogonias furnieri) of southeastern Brazil: A geochemical proxy for environmental preference","authors":"M. Lopes, O. Aguilera, C. Monteiro-Neto, N. Miller, M. D. Gaspar, M. R. Costa","doi":"10.1177/09596836231163510","DOIUrl":"https://doi.org/10.1177/09596836231163510","url":null,"abstract":"In this study, laser ablation–inductively coupled plasma–mass spectrometry was used to characterize the growth patterns of otolith of Micropogonias furnieri from southeastern Brazil under the influence of coastal marine upwelling. Archaeological fish sagittae otoliths of M. furnieri recovered from Brazilian shell mounds (5820‒4980 cal BP) were analysed and compared with those of modern specimens. Otolith Sr/Ca analysis indicated that off southeastern Brazil, M. furnieri shifted from freshwater/brackish in archaeological specimens to brackish/marine in modern times. Regular core-to-edge Sr/Ca oscillations suggest that both modern and archaeological M. furnieri are resident estuarine fish that also use the marine waters adjacent to the coastal zone. Based on analyses of a wide range of otolith edge Sr/Ca values measured in archaeological samples, pre-colonial fishing activities in the coastal regions of Guanabara Bay occurred throughout the year. This study reinforces the importance of M. furnieri as a precolonial fishing resource in this area and demonstrates a shift in fishing practices, where smaller fish are targetted within the bay and larger fish are caught beyond the bay. These data may also be indicative of a shift in the life cycle of this species, possibly caused by the overfishing of this important resource and significant increase in human activities in protected coastal waters in modern times.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47270942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-18DOI: 10.1177/09596836231163508
Z. Ön, N. Macdonald, Sena Akçer-Ön, A. Greaves
Climate reconstructions derived from proxy records for individual sites often fail to incorporate existing regional information, which may help to determine uncertainties and express variability within specific reconstructions or commonalities between datasets. Such an understanding is crucial when examining past human-environment interactions. Taking the eastern Mediterranean as our case study, we present here a new air temperature model for the last 10,000 years that utilises data from 33 previously published proxy-based independent reconstructions, using a novel fully Bayesian approach that applies multilevel regression models of individual temperature datasets grouped together into 300 year long consecutive sub-intervals. A Bayesian multilevel approach allows the model to share information between each regression model from the individual datasets and the 300 year grouped regression models. The results demonstrate commonalities between individual datasets derived from different sources, and embed the uncertainties within the model. Our results establish that the eastern Mediterranean region was consistently warmer than the 20th century, except for two short intervals at the end of the Early Holocene (between 8400 and 8250 yrs BP) and the start of the mid-Holocene (between 7800 and 7650 yrs BP). We also identify changes within temperature associated with both the 8.2 ka and 4.2 ka BP events, however our findings identify regional warming in the eastern Mediterranean, rather than cooling often associated with the 4.2 ka BP event. Our results are comparable with previous large scale hemispheric reconstructions, demonstrating that our model is a robust candidate for temperature reconstructions within a confined region, which can range from mesoscale up to macroscale.
根据个别地点的代理记录进行的气候重建往往无法纳入现有的区域信息，这可能有助于确定不确定性，并表达特定重建中的可变性或数据集之间的共性。在考察过去人类与环境的相互作用时，这种理解至关重要。以地中海东部为例，我们在这里提出了一个新的过去10000年的气温模型 年，利用33个先前发表的基于代理的独立重建数据，使用一种新颖的完全贝叶斯方法，将单个温度数据集的多级回归模型分组为300 长达一年的连续子区间。贝叶斯多级方法允许模型在来自单个数据集的每个回归模型和300 年分组回归模型。结果证明了来自不同来源的单个数据集之间的共性，并将不确定性嵌入到模型中。我们的研究结果表明，地中海东部地区一直比20世纪更温暖，除了全新世早期结束时的两个短时间间隔（8400年至8250年之间 BP年）和全新世中期（7800年至7650年） 年BP）。我们还确定了与8.2 ka和4.2 ka BP事件，然而，我们的发现确定了地中海东部的区域变暖，而不是通常与4.2 ka BP事件。我们的结果与以前的大尺度半球重建结果相当，表明我们的模型是有限区域内温度重建的有力候选者，该区域可以从中尺度到宏观尺度。
{"title":"A novel Bayesian multilevel regression approach to the reconstruction of an eastern Mediterranean temperature record for the last 10,000 years","authors":"Z. Ön, N. Macdonald, Sena Akçer-Ön, A. Greaves","doi":"10.1177/09596836231163508","DOIUrl":"https://doi.org/10.1177/09596836231163508","url":null,"abstract":"Climate reconstructions derived from proxy records for individual sites often fail to incorporate existing regional information, which may help to determine uncertainties and express variability within specific reconstructions or commonalities between datasets. Such an understanding is crucial when examining past human-environment interactions. Taking the eastern Mediterranean as our case study, we present here a new air temperature model for the last 10,000 years that utilises data from 33 previously published proxy-based independent reconstructions, using a novel fully Bayesian approach that applies multilevel regression models of individual temperature datasets grouped together into 300 year long consecutive sub-intervals. A Bayesian multilevel approach allows the model to share information between each regression model from the individual datasets and the 300 year grouped regression models. The results demonstrate commonalities between individual datasets derived from different sources, and embed the uncertainties within the model. Our results establish that the eastern Mediterranean region was consistently warmer than the 20th century, except for two short intervals at the end of the Early Holocene (between 8400 and 8250 yrs BP) and the start of the mid-Holocene (between 7800 and 7650 yrs BP). We also identify changes within temperature associated with both the 8.2 ka and 4.2 ka BP events, however our findings identify regional warming in the eastern Mediterranean, rather than cooling often associated with the 4.2 ka BP event. Our results are comparable with previous large scale hemispheric reconstructions, demonstrating that our model is a robust candidate for temperature reconstructions within a confined region, which can range from mesoscale up to macroscale.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47253934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-17DOI: 10.1177/09596836231163486
Sumit Sagwal, Adarsh Kumar, C. Sharma, P. Srivastava, Shravi Agarwal, R. Bhushan
Variations in lake-levels and hydrology are connected to climatic dynamics over the Trans-Himalaya and Tibetan Plateau (TP). Pangong Tso, a ~140 km long hypersaline lake, is sensitive to changes in air temperature, precipitation and snow-glacier melt over the southwestern TP. The incised tributaries entering the lake expose deltaic sequences constituting topset, foreset and bottomset. Sedimentology, chronology and diatom analysis of delta sediments; and stable isotopic and sclerochronological analysis of gastropods helped delineate the Late-Holocene variation in lake levels, surface temperature and salinity. The elevation of the topsets is considered as representing past lake high-stands from where molluscs were also recovered. Three phased lake level changes are observed during the past 3 ka. The first high-stand (+1.4–3.0 m) was at ~2.8–2.0 ka when lake surface salinity and temperature were 4.67–6.01 ppt (parts per thousand) and 5°C–7°C, respectively, against the modern average values of 7.7 ± 0.09 ppt and 16.1°C ± 2.0°C. Followed by a brief decline, another high-stand (+3.0–3.6 m) is observed at 1.1 ka when the salinity is reduced to 4.03–5.72 ppt and lake surface temperature to 5°C–8°C. A corresponding increase in freshwater diatom concentration is also observed here. The third phase over the past 1 ka witnessed a fall of ~3.6–6 m in lake level that is attributed to an abrupt rise in aridity over the TP. We demonstrate that lake level variation in the region is a function of the variability of the Indian Summer Monsoon (ISM) and the westerlies, however during the high-stand, the hydrology of the lake was dominated by ISM precipitation.
{"title":"Late-Holocene hydrological variability from the NW Himalaya and southwestern Tibetan Plateau: Paleo-salinity records from Pangong Tso","authors":"Sumit Sagwal, Adarsh Kumar, C. Sharma, P. Srivastava, Shravi Agarwal, R. Bhushan","doi":"10.1177/09596836231163486","DOIUrl":"https://doi.org/10.1177/09596836231163486","url":null,"abstract":"Variations in lake-levels and hydrology are connected to climatic dynamics over the Trans-Himalaya and Tibetan Plateau (TP). Pangong Tso, a ~140 km long hypersaline lake, is sensitive to changes in air temperature, precipitation and snow-glacier melt over the southwestern TP. The incised tributaries entering the lake expose deltaic sequences constituting topset, foreset and bottomset. Sedimentology, chronology and diatom analysis of delta sediments; and stable isotopic and sclerochronological analysis of gastropods helped delineate the Late-Holocene variation in lake levels, surface temperature and salinity. The elevation of the topsets is considered as representing past lake high-stands from where molluscs were also recovered. Three phased lake level changes are observed during the past 3 ka. The first high-stand (+1.4–3.0 m) was at ~2.8–2.0 ka when lake surface salinity and temperature were 4.67–6.01 ppt (parts per thousand) and 5°C–7°C, respectively, against the modern average values of 7.7 ± 0.09 ppt and 16.1°C ± 2.0°C. Followed by a brief decline, another high-stand (+3.0–3.6 m) is observed at 1.1 ka when the salinity is reduced to 4.03–5.72 ppt and lake surface temperature to 5°C–8°C. A corresponding increase in freshwater diatom concentration is also observed here. The third phase over the past 1 ka witnessed a fall of ~3.6–6 m in lake level that is attributed to an abrupt rise in aridity over the TP. We demonstrate that lake level variation in the region is a function of the variability of the Indian Summer Monsoon (ISM) and the westerlies, however during the high-stand, the hydrology of the lake was dominated by ISM precipitation.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48462277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-17DOI: 10.1177/09596836231163505
Satabdi Mohanty, Swagata Chaudhuri, A. K. Bhaumik, Pankaj Kumar
The present work is pursued on the benthic foraminiferal groups obtained from NGHP core samples of the western Bay of Bengal to understand the variations of paleoceanography and Indian Summer Monsoon (ISM), as well as socio-economic changes in ancient India. Benthic foraminiferal AMS 14C dating reveals that the studied interval spans between 335 BC and 1355 AD, covering the history of the last 1690 years. We compared foraminifera group counts with published isotopes, sunspot number, summer monsoon index, hematite-stained grain, Al/Ca, 14C data sets. Angular Asymmetrical Benthic Foraminifera, infaunal, and dysoxic groups exhibit declining trends with warm, humid intervals with intensified ISM signature from 335 BC to 406 AD (Roman Warm Period) and from 787 to 1202 AD (Medieval Warm Period). The Increasing trend of the above foraminiferal groups captures the signature of weak ISM from 406 to 787 AD (Dark Age Cold Period) and from 1202 to 1355 AD (Medieval Warm Period and Little Ice Age Transition). Whereas rounded symmetrical benthic foraminifera, epifaunal, and oxic groups show a reverse relation with the abovementioned groups. Spectral analysis of foraminiferal groups shows significant periodicities of 563/561, 450, 321, 281/250, 22/27, and 17/16/15 years, corresponding to various solar cycles. This research uncovers the relationship between solar activity and monsoonal changes, which influenced India’s economic growth and played a crucial role in the establishment and demise of successive dynasties throughout the Indian subcontinent during the late-Holocene.
{"title":"Late-Holocene paleoceanographic and climatic changes and their impact on Indian socio-economic conditions: Benthic foraminiferal evidence from the Bay of Bengal","authors":"Satabdi Mohanty, Swagata Chaudhuri, A. K. Bhaumik, Pankaj Kumar","doi":"10.1177/09596836231163505","DOIUrl":"https://doi.org/10.1177/09596836231163505","url":null,"abstract":"The present work is pursued on the benthic foraminiferal groups obtained from NGHP core samples of the western Bay of Bengal to understand the variations of paleoceanography and Indian Summer Monsoon (ISM), as well as socio-economic changes in ancient India. Benthic foraminiferal AMS 14C dating reveals that the studied interval spans between 335 BC and 1355 AD, covering the history of the last 1690 years. We compared foraminifera group counts with published isotopes, sunspot number, summer monsoon index, hematite-stained grain, Al/Ca, 14C data sets. Angular Asymmetrical Benthic Foraminifera, infaunal, and dysoxic groups exhibit declining trends with warm, humid intervals with intensified ISM signature from 335 BC to 406 AD (Roman Warm Period) and from 787 to 1202 AD (Medieval Warm Period). The Increasing trend of the above foraminiferal groups captures the signature of weak ISM from 406 to 787 AD (Dark Age Cold Period) and from 1202 to 1355 AD (Medieval Warm Period and Little Ice Age Transition). Whereas rounded symmetrical benthic foraminifera, epifaunal, and oxic groups show a reverse relation with the abovementioned groups. Spectral analysis of foraminiferal groups shows significant periodicities of 563/561, 450, 321, 281/250, 22/27, and 17/16/15 years, corresponding to various solar cycles. This research uncovers the relationship between solar activity and monsoonal changes, which influenced India’s economic growth and played a crucial role in the establishment and demise of successive dynasties throughout the Indian subcontinent during the late-Holocene.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47452670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-16DOI: 10.1177/09596836231163506
O. Adojoh, F. Marret, R. Duller, P. Osterloff, F. Oboh-Ikuenobe, B. Saylor
This study used the comparative analysis of 3 gravity cores (GCs) obtained from the shallow offshore at ~40 m water depth to reconstruct the morphological evolution of the delta (East Equatorial Atlantic). The focus of this study is on the interpretation of elemental tracers and their justification between these tracers and microfossil data to understand the impact of climate-sea level controls on the evolution of the Niger Delta during the Late Quaternary. Key elemental tracers comprising Ti, Zr, Fe and S were explored to strengthen this concept. High Ti/Zr ratio values down-hole indicate fluvial transport of terrestrial components to the marine setting (20–11.7 ka), whereas high values of Fe/S ratio up-hole provide an extent of inherent marine shale of the Niger Delta (11.7–6.5 ka). In addition, the integrated multiple proxy (mangrove and hinterland pollen, planktonic foraminifera and sedimentary facies) with elemental tracer ratios provided robust and coherent information for delineating the late glacial (MIS2) prograding and interglacial (MIS1) retrograding deltaic transition, respectively. The overall trends of the two elemental tracer ratios (Lower and Mid-upper depths of the GCs) provide a new distinction on the depositional patterns (prograding and retrograding delta) to determine the proximal/upper (clay, silt and very fine sand) and distal offshore/lower shorefaces (coarse-medium sand), and gross palaeoenvironments based on planktonic foraminifera records. These sequential records provide a new clue as evidence of the morphological evolutionary stages (delta plain, delta front and prodelta) of the Niger Delta landscape, gross palaeoenvironments, and vegetation dynamics (pollen data) during two distinct time-bound intervals (20–6.5 ka), which potentially delineate the climate and sea level regime of the coastal offshore.
{"title":"Stages of palaeoenvironmental evolution, climate and sea level change of the Niger Delta, east Equatorial Atlantic: Novelty from elemental tracers, sedimentary facies and pollen records","authors":"O. Adojoh, F. Marret, R. Duller, P. Osterloff, F. Oboh-Ikuenobe, B. Saylor","doi":"10.1177/09596836231163506","DOIUrl":"https://doi.org/10.1177/09596836231163506","url":null,"abstract":"This study used the comparative analysis of 3 gravity cores (GCs) obtained from the shallow offshore at ~40 m water depth to reconstruct the morphological evolution of the delta (East Equatorial Atlantic). The focus of this study is on the interpretation of elemental tracers and their justification between these tracers and microfossil data to understand the impact of climate-sea level controls on the evolution of the Niger Delta during the Late Quaternary. Key elemental tracers comprising Ti, Zr, Fe and S were explored to strengthen this concept. High Ti/Zr ratio values down-hole indicate fluvial transport of terrestrial components to the marine setting (20–11.7 ka), whereas high values of Fe/S ratio up-hole provide an extent of inherent marine shale of the Niger Delta (11.7–6.5 ka). In addition, the integrated multiple proxy (mangrove and hinterland pollen, planktonic foraminifera and sedimentary facies) with elemental tracer ratios provided robust and coherent information for delineating the late glacial (MIS2) prograding and interglacial (MIS1) retrograding deltaic transition, respectively. The overall trends of the two elemental tracer ratios (Lower and Mid-upper depths of the GCs) provide a new distinction on the depositional patterns (prograding and retrograding delta) to determine the proximal/upper (clay, silt and very fine sand) and distal offshore/lower shorefaces (coarse-medium sand), and gross palaeoenvironments based on planktonic foraminifera records. These sequential records provide a new clue as evidence of the morphological evolutionary stages (delta plain, delta front and prodelta) of the Niger Delta landscape, gross palaeoenvironments, and vegetation dynamics (pollen data) during two distinct time-bound intervals (20–6.5 ka), which potentially delineate the climate and sea level regime of the coastal offshore.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43476539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-16DOI: 10.1177/09596836231163512
David Noncent, A. Sifeddine, E. Emmanuel, M. Cormier, F. Briceño‐Zuluaga, M. Mendez‐Millan, B. Turcq, S. Caquineau, J. Valdés, J. Bernal, J. King, Irina Djouraev, Fethiye Çetin, H. Sloan
This study aims to reconstruct the hydro-climatic variations over the last 1000 years in Haiti using mineralogical and geochemical composition of well dated lacustrine sediment core retrieved from Lake Azuei. The results show changes in sedimentological processes linked to environmental and climatic variations. The general pattern suggests a wetter Medieval Climate Anomaly (MCA), drier Little Ice Age (LIA), high climate variability during the MCA-LIA transition and more anthropogenic impacts that dominate natural climate during the Current Warm Period (CWP). The MCA period (~1000–1100 CE) thus appears marked by increase sedimentation rate supported by higher terrigenous input linked to erosive events particularly increases in precipitation. During the LIA, particularly from ~1450 to 1600 CE, there is a great variation toward a decrease of terrigenous input, which is related to a decrease on sedimentation rate and increase Mg-calcite precipitation, suggesting less precipitation and high evaporation respectively during dry climate conditions. The MCA-LIA transition (~1200–1400 CE) is characterized by variations between terrigenous input, Mg-calcite formation and organic matter deposition, which indicate succession of dry and humid conditions. The CWP (1800–2000 CE) shows a progressive increase on sedimentation rate and decrease of gray level, which indicate more organic matter sedimentation as consequence of anthropogenic activities in the surrounding basin of the lake. High-resolution gray level analysis, which reflects principally variations in terrigenous input, carbonate mineral formation and organic matter deposition, shows that the AMO, NAO, PDO and ENSO are the principal modes affecting the hydro-climatic changes in Haiti during the last millennium. In addition, temporal correlation of other Caribbean paleoclimate records with our geochemical and mineralogical data, suggests that trends observed in Lake Azuei were controlled by regional climate, likely associated with shifts in the position of the ITCZ.
{"title":"Hydroclimate reconstruction during the last 1000 years inferred from the mineralogical and geochemical composition of a sediment core from Lake-Azuei (Haiti)","authors":"David Noncent, A. Sifeddine, E. Emmanuel, M. Cormier, F. Briceño‐Zuluaga, M. Mendez‐Millan, B. Turcq, S. Caquineau, J. Valdés, J. Bernal, J. King, Irina Djouraev, Fethiye Çetin, H. Sloan","doi":"10.1177/09596836231163512","DOIUrl":"https://doi.org/10.1177/09596836231163512","url":null,"abstract":"This study aims to reconstruct the hydro-climatic variations over the last 1000 years in Haiti using mineralogical and geochemical composition of well dated lacustrine sediment core retrieved from Lake Azuei. The results show changes in sedimentological processes linked to environmental and climatic variations. The general pattern suggests a wetter Medieval Climate Anomaly (MCA), drier Little Ice Age (LIA), high climate variability during the MCA-LIA transition and more anthropogenic impacts that dominate natural climate during the Current Warm Period (CWP). The MCA period (~1000–1100 CE) thus appears marked by increase sedimentation rate supported by higher terrigenous input linked to erosive events particularly increases in precipitation. During the LIA, particularly from ~1450 to 1600 CE, there is a great variation toward a decrease of terrigenous input, which is related to a decrease on sedimentation rate and increase Mg-calcite precipitation, suggesting less precipitation and high evaporation respectively during dry climate conditions. The MCA-LIA transition (~1200–1400 CE) is characterized by variations between terrigenous input, Mg-calcite formation and organic matter deposition, which indicate succession of dry and humid conditions. The CWP (1800–2000 CE) shows a progressive increase on sedimentation rate and decrease of gray level, which indicate more organic matter sedimentation as consequence of anthropogenic activities in the surrounding basin of the lake. High-resolution gray level analysis, which reflects principally variations in terrigenous input, carbonate mineral formation and organic matter deposition, shows that the AMO, NAO, PDO and ENSO are the principal modes affecting the hydro-climatic changes in Haiti during the last millennium. In addition, temporal correlation of other Caribbean paleoclimate records with our geochemical and mineralogical data, suggests that trends observed in Lake Azuei were controlled by regional climate, likely associated with shifts in the position of the ITCZ.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48446317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-05DOI: 10.1177/09596836231163515
E. Cagliero, L. Paradis, N. Marchi, Zsuzsa Lisztes-Szabó, M. Braun, Katalin Hubay, P. Sabatier, M. Čurović, V. Spalević, R. Motta, E. Lingua, W. Finsinger
We present the first high-resolution Holocene pollen, plant-macrofossil, and charcoal records from the upper-montane zone in the central Dinaric Alps. Drawing on these new records from well-dated lacustrine sediments of Zminje Jezero (ca. 1500 m a.s.l.; Montenegro) and on independent chironomid-inferred summer temperatures, we explore long-term ecosystem responses to variations in climate, fire disturbances and land use, as well as legacy effects of past environmental changes. A mixed spruce-fir forest established in the upper-montane zone around 9500 cal BP, and Fagus sylvatica became co-dominant with the two conifers after 5000 cal BP. Prehistoric land-use pressure was overall remarkably low, but increased since 2000 cal BP and was highest after the Middle Ages. We found a significant positive relationship between biomass burning and summer temperature, indicating that fires were mostly climate driven. Picea abies was insensitive to summer temperature, biomass burning and human impact, which supports the view that spruce forests may not be significantly impacted by fire. In contrast, Abies alba and other disturbance-sensitive trees (Tilia, Ulmus, Fraxinus excelsior-type) show significant negative responses to land-use pressure and positive responses to summer temperature. This supports the notion that these species may be well-adapted to warmer-than present summer temperatures and that their populations declined in recent millennia due to land-use activities. Conversely, F. sylvatica was sensitive to summer temperatures but was promoted by low biomass burning, indicating that its expansion in the spruce-fir dominated forest was enhanced by the onset of cooler and possibly also moister climatic conditions as well as by fire disturbances.
本文提出了第一个高分辨率的全新世花粉、植物大化石和木炭记录，这些记录来自第纳尔阿尔卑斯山脉中部的高山地带。利用这些来自Zminje Jezero(约1500 m a.s.l.)湖相沉积物的新记录;黑山)和独立的chironomid推断的夏季温度，我们探索长期生态系统对气候、火灾干扰和土地利用变化的响应，以及过去环境变化的遗留影响。9500 cal BP前后，高山地区形成了云杉混交林，5000 cal BP后，山毛榉与两种针叶树形成了共同优势。史前土地利用压力总体上非常低，但自2000 cal BP以来有所增加，并在中世纪之后达到最高。我们发现生物质燃烧与夏季温度之间存在显著的正相关关系，表明火灾主要是气候驱动的。云杉林对夏季温度、生物质燃烧和人为影响不敏感，这支持了云杉林可能不受火灾影响的观点。相比之下，冷杉和其他干扰敏感树种(椴、榆木、黄曲霉)对土地利用压力表现出显著的负响应，对夏季温度表现出显著的正响应。这支持了这样一种观点，即这些物种可能很好地适应了比现在更温暖的夏季温度，并且由于土地利用活动，它们的数量在近几千年来有所下降。相反，F. sylvatica对夏季温度敏感，但较少的生物质燃烧促进了它的生长，这表明它在云杉为主的森林中的扩张受到了更凉爽、更湿润的气候条件以及火灾干扰的促进。
{"title":"The role of fire disturbances, human activities and climate change for long-term forest dynamics in upper-montane forests of the central Dinaric Alps","authors":"E. Cagliero, L. Paradis, N. Marchi, Zsuzsa Lisztes-Szabó, M. Braun, Katalin Hubay, P. Sabatier, M. Čurović, V. Spalević, R. Motta, E. Lingua, W. Finsinger","doi":"10.1177/09596836231163515","DOIUrl":"https://doi.org/10.1177/09596836231163515","url":null,"abstract":"We present the first high-resolution Holocene pollen, plant-macrofossil, and charcoal records from the upper-montane zone in the central Dinaric Alps. Drawing on these new records from well-dated lacustrine sediments of Zminje Jezero (ca. 1500 m a.s.l.; Montenegro) and on independent chironomid-inferred summer temperatures, we explore long-term ecosystem responses to variations in climate, fire disturbances and land use, as well as legacy effects of past environmental changes. A mixed spruce-fir forest established in the upper-montane zone around 9500 cal BP, and Fagus sylvatica became co-dominant with the two conifers after 5000 cal BP. Prehistoric land-use pressure was overall remarkably low, but increased since 2000 cal BP and was highest after the Middle Ages. We found a significant positive relationship between biomass burning and summer temperature, indicating that fires were mostly climate driven. Picea abies was insensitive to summer temperature, biomass burning and human impact, which supports the view that spruce forests may not be significantly impacted by fire. In contrast, Abies alba and other disturbance-sensitive trees (Tilia, Ulmus, Fraxinus excelsior-type) show significant negative responses to land-use pressure and positive responses to summer temperature. This supports the notion that these species may be well-adapted to warmer-than present summer temperatures and that their populations declined in recent millennia due to land-use activities. Conversely, F. sylvatica was sensitive to summer temperatures but was promoted by low biomass burning, indicating that its expansion in the spruce-fir dominated forest was enhanced by the onset of cooler and possibly also moister climatic conditions as well as by fire disturbances.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43621252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-04-01DOI: 10.1177/09596836231157065
Marta Korczyńska-Cappenberg, M. Nowak, A. Mueller-Bieniek, J. Wilczyński, Sylwia Pospuła, Krzysztof Wertz, T. Kalicki, Piotr Biesaga, P. Szwarczewski, Magda Kapcia, K. Cappenberg, A. Wacnik, Magdalena Moskal-del Hoyo
Palaeoecological and archaeological studies conducted in Mozgawa (southern Poland) demonstrated a long-term sustainable land-use by inhabitants of a large settlement occupied during the second half of the fourth millennium BC. The Middle Neolithic society established a settlement that covered an area of about 30–35 ha and functioned during at least three centuries, as validated by the absolute chronology. A thorough analysis based on the fuzzy-logic principle combined with archaeobotanical and archaeozoological data showed that the subsistence model was based on agricultural practices, related with both crop cultivation and animal husbandry, together with an important component of hunting, fishing and gathering. Ecological requirements of plants and animals represented by fossil remains suggested that the exploited area included a variety of habitats. In the open landscape, wet and dry grasslands, used partly as pastures, cultivated fields and marshes were present. Wooded areas included deciduous lime-oak-elm forests, also of open canopy type, and riparian forests. This was due to the transitional location of the Mozgawa site on a loess-mantled hill, covered with fertile soils, but right on the border with a vast alluvial plain of the Nida River. Such ecologically diversified micro-region became a managed landscape, which provided rich resources for seasonal diets of the settlement’s inhabitants. The case study of the Mozgawa site offers a unique insight into the palaeoeconomy of the Funnel Beaker culture in central Europe.
{"title":"Middle Neolithic agricultural and land-use models in southern Poland: A case-study of the long-term settlement in Mozgawa","authors":"Marta Korczyńska-Cappenberg, M. Nowak, A. Mueller-Bieniek, J. Wilczyński, Sylwia Pospuła, Krzysztof Wertz, T. Kalicki, Piotr Biesaga, P. Szwarczewski, Magda Kapcia, K. Cappenberg, A. Wacnik, Magdalena Moskal-del Hoyo","doi":"10.1177/09596836231157065","DOIUrl":"https://doi.org/10.1177/09596836231157065","url":null,"abstract":"Palaeoecological and archaeological studies conducted in Mozgawa (southern Poland) demonstrated a long-term sustainable land-use by inhabitants of a large settlement occupied during the second half of the fourth millennium BC. The Middle Neolithic society established a settlement that covered an area of about 30–35 ha and functioned during at least three centuries, as validated by the absolute chronology. A thorough analysis based on the fuzzy-logic principle combined with archaeobotanical and archaeozoological data showed that the subsistence model was based on agricultural practices, related with both crop cultivation and animal husbandry, together with an important component of hunting, fishing and gathering. Ecological requirements of plants and animals represented by fossil remains suggested that the exploited area included a variety of habitats. In the open landscape, wet and dry grasslands, used partly as pastures, cultivated fields and marshes were present. Wooded areas included deciduous lime-oak-elm forests, also of open canopy type, and riparian forests. This was due to the transitional location of the Mozgawa site on a loess-mantled hill, covered with fertile soils, but right on the border with a vast alluvial plain of the Nida River. Such ecologically diversified micro-region became a managed landscape, which provided rich resources for seasonal diets of the settlement’s inhabitants. The case study of the Mozgawa site offers a unique insight into the palaeoeconomy of the Funnel Beaker culture in central Europe.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43342041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 : 2023-03-29DOI: 10.1177/09596836231157059
Pablo Heredia Barión, S. Roberts, C. Spiegel, S. Binnie, L. Wacker, J. Davies, Imogen Gabriel, V. Jones, S. Blockley, E. Pearson, Louise C. Foster, S. Davies, T. Roland, Emma P. Hocking, M. J. Bentley, D. Hodgson, C. Hayward, R. McCulloch, J. Strelin, G. Kuhn
To provide insights into glacier-climate dynamics of the South Shetland Islands (SSI), NW Antarctic Peninsula, we present a new deglaciation and readvance model for the Bellingshausen Ice Cap (BIC) on Fildes Peninsula and for King George Island/Isla 25 de Mayo (KGI) ~62°S. Deglaciation on KGI began after c. 15 cal. ka BP and had progressed to within present-day limits on the Fildes Peninsula, its largest ice-free peninsula, by c. 6.6–5.3 cal. ka BP. Probability density phase analysis of chronological data constraining Holocene glacier advances on KGI revealed up to eight 95% probability ‘gaps’ during which readvances could have occurred. These are grouped into four stages – Stage 1: a readvance and marine transgression, well-constrained by field data, between c. 7.4 and 6.6 cal. ka BP; Stage 2: four probability ‘gaps’, less well-constrained by field data, between c. 5.3 and 2.2 cal. ka BP; Stage 3: a well-constrained but restricted ‘readvance’ between c. 1.7 and 1.5 cal. ka BP; Stage 4: two further minor ‘readvances’, one less well-constrained by field data between c. 1.3 and 0.7 cal. ka BP (68% probability), and a ‘final’ well-constrained ‘readvance’ after <0.7 cal. ka BP. The Stage 1 readvance occurred as colder and more negative Southern Annular Mode (SAM)-like conditions developed, and marginally stronger/poleward shifted westerly winds led to more storms and precipitation on the SSI. Readvances after c. 5.3 cal. ka BP were possibly more frequent, driven by reducing spring/summer insolation at 62°S and negative SAM-like conditions, but weaker (equatorward shifted) Westerlies over the SSI led to reduced storminess, restricting readvances within or close to present day limits. Late Holocene readvances were anti-phased with subaquatic freshwater moss layers in lake records unaffected by glaciofluvial inputs. Retreat from ‘Neoglacial’ glacier limits and the recolonisation of lakes by subaquatic freshwater moss after 1950 CE is associated with recent warming/more positive SAM-like conditions.
{"title":"Holocene deglaciation and glacier readvances on the Fildes Peninsula and King George Island (Isla 25 de Mayo), South Shetland Islands, NW Antarctic Peninsula","authors":"Pablo Heredia Barión, S. Roberts, C. Spiegel, S. Binnie, L. Wacker, J. Davies, Imogen Gabriel, V. Jones, S. Blockley, E. Pearson, Louise C. Foster, S. Davies, T. Roland, Emma P. Hocking, M. J. Bentley, D. Hodgson, C. Hayward, R. McCulloch, J. Strelin, G. Kuhn","doi":"10.1177/09596836231157059","DOIUrl":"https://doi.org/10.1177/09596836231157059","url":null,"abstract":"To provide insights into glacier-climate dynamics of the South Shetland Islands (SSI), NW Antarctic Peninsula, we present a new deglaciation and readvance model for the Bellingshausen Ice Cap (BIC) on Fildes Peninsula and for King George Island/Isla 25 de Mayo (KGI) ~62°S. Deglaciation on KGI began after c. 15 cal. ka BP and had progressed to within present-day limits on the Fildes Peninsula, its largest ice-free peninsula, by c. 6.6–5.3 cal. ka BP. Probability density phase analysis of chronological data constraining Holocene glacier advances on KGI revealed up to eight 95% probability ‘gaps’ during which readvances could have occurred. These are grouped into four stages – Stage 1: a readvance and marine transgression, well-constrained by field data, between c. 7.4 and 6.6 cal. ka BP; Stage 2: four probability ‘gaps’, less well-constrained by field data, between c. 5.3 and 2.2 cal. ka BP; Stage 3: a well-constrained but restricted ‘readvance’ between c. 1.7 and 1.5 cal. ka BP; Stage 4: two further minor ‘readvances’, one less well-constrained by field data between c. 1.3 and 0.7 cal. ka BP (68% probability), and a ‘final’ well-constrained ‘readvance’ after <0.7 cal. ka BP. The Stage 1 readvance occurred as colder and more negative Southern Annular Mode (SAM)-like conditions developed, and marginally stronger/poleward shifted westerly winds led to more storms and precipitation on the SSI. Readvances after c. 5.3 cal. ka BP were possibly more frequent, driven by reducing spring/summer insolation at 62°S and negative SAM-like conditions, but weaker (equatorward shifted) Westerlies over the SSI led to reduced storminess, restricting readvances within or close to present day limits. Late Holocene readvances were anti-phased with subaquatic freshwater moss layers in lake records unaffected by glaciofluvial inputs. Retreat from ‘Neoglacial’ glacier limits and the recolonisation of lakes by subaquatic freshwater moss after 1950 CE is associated with recent warming/more positive SAM-like conditions.","PeriodicalId":50402,"journal":{"name":"Holocene","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47672218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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