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New Perspectives on the Quaternary Paleogeography of Coastal Ecuador and Its Relationships with Climate Change 厄瓜多尔海岸第四纪古地理及其与气候变化关系的新视角
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-07-13 DOI: 10.3390/quat6030041
María Quiñónez-Macías, K. Chunga, T. Toulkeridis, Alvaro Mora-Mendoza, Angelo Constantine
Well-preserved Quaternary sedimentary sequences in the central coast of Ecuador have provided sufficient relevant information for paleogeographic reconstruction and climatic evolution, from stratigraphic, geochemical, and biological analysis. The Jaramijo canton site is one of the most remarkable results in the stratigraphic correlation of lithological units with delineation of a paleo sea-cliff of age 14C 43,245 ± 460 B.P. (belonging to the MIS-3). This MIS-3 is associated with a period of glaciation, but the data obtained, such as δ 18O, indicate paleo-temperature values of −1 to −1.5, which are interpreted in this study, indicate that the central coast of Ecuador has an interstadial phase (warm years in a glacial stage). Two more paleo-coastal cliffs have been mapped from orthophoto analysis, but these are younger. The sedimentary levels analyzed in this study include deposits that occurred in MIS 3 to MIS 1. Holocene transgression has modified the central coast of Ecuador and increased the level of coastal climate hazard by sea level rise. Indeed, paleo-coastlines have been evidenced from bathymetric data in the depth contours of −5.5 m and −7.6 m, at 440 and 650 m distances from the up-to-date coastline. For the Jaramijó site, the rate of cliff-erosion and wave-cut platforms are in the order of 1.1 to 2.4 m/yr. These cliff-erosion rates, with a moderate to high coastal vulnerability index, can be increased if we consider mathematical models with an estimated sea-level rise scenario to be, in 2100, about +1 to +1.4 m.
厄瓜多尔中部海岸保存完好的第四纪沉积序列,通过地层、地球化学和生物分析,为古地理重建和气候演化提供了充足的相关信息。Jaramijo canton遗址是岩性单元地层对比中最显著的成果之一,描绘了年龄为14C 43245±460 B.P.的古海崖(属于MIS-3)。这一MIS-3与一段冰川作用时期有关,但所获得的数据,如δ18O,表明古温度值为−1至−1.5,本研究对此进行了解释,表明厄瓜多尔中部海岸具有温带阶段(冰川期的温暖年份)。通过正射影像分析,又绘制了两个古海岸悬崖的地图,但这些悬崖更年轻。本研究中分析的沉积水平包括MIS 3至MIS 1中的矿床。全新世海侵改变了厄瓜多尔中部海岸,海平面上升增加了沿海气候危害程度。事实上,在距离最新海岸线440米和650米处,−5.5米和−7.6米深度等值线的测深数据证明了古海岸线。对于Jaramijó遗址,悬崖侵蚀和波浪切割平台的速率约为1.1至2.4米/年。如果我们考虑数学模型,估计2100年海平面上升情景约为+1至+1.4米,这些悬崖侵蚀率和中等至高海岸脆弱性指数可以增加。
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引用次数: 0
Magnetic Susceptibility Prospecting and Geochemical Characterization of Taxco’s Mining Waste Dam Guerrero I (Mexico) 墨西哥Taxco矿业废料坝Guerrero I的磁化率找矿及地球化学特征
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-07-05 DOI: 10.3390/quat6030040
J. Morales, María del Sol Hernández Bernal, Nayeli Pérez Rodríguez, A. Goguitchaichvili
Mining activity at Taxco produces seven mining waste deposits, which are problematic for the health of the community and for the environment in general. This study targets the Guerrero I mining waste dam (the youngest of the region), located south of Taxco de Alarcon, in the northern portion of Guerrero State, Mexico. This study reports the vertical magnetic susceptibility prospecting results and geochemical characterization of 27 tailing samples from the Guerrero I dam. Results from magnetic techniques provide evidence for different deposit layers of variable mineral composition, in agreement with the lithological column. The short evolution period of this relatively young dam is corroborated by the practically constant and close to 1 S-300 ratio (low oxidation degree of the magnetic mineralogy) and the mainly neutral pH character at the dam’s upper part. Most maximum concentrations of potentially toxic elements are below the maximum permissible levels for agriculture/residential use, except for those of Pb and Zn, with average enrichment factors above 90 and 50 times the corresponding regional background concentrations, respectively. Simple sample preparation and fast magnetic and X-ray fluorescence elemental concentration measurements, together with a suitable systematic sampling distribution, result in an advantageous proxy method for a quick and cost-effective heavy metal evaluation of mining waste dams.
Taxco的采矿活动产生了七个采矿废物矿床,这对社区健康和整个环境都有问题。这项研究的目标是位于墨西哥格雷罗州北部Taxco de Alarcon以南的格雷罗一号采矿废料坝(该地区最年轻的)。本研究报告了格雷罗一号大坝27个尾矿样品的垂直磁化率勘探结果和地球化学特征。磁性技术的结果为不同矿物成分的矿床层提供了证据,与岩性柱一致。这个相对年轻的大坝的短演化期得到了大坝上部几乎恒定且接近1S-300的比率(磁性矿物学的低氧化度)和主要中性pH特征的证实。除Pb和Zn外,大多数潜在有毒元素的最大浓度都低于农业/住宅使用的最大允许水平,平均富集系数分别高于相应区域背景浓度的90倍和50倍。简单的样品制备和快速的磁性和X射线荧光元素浓度测量,再加上合适的系统采样分布,为快速、经济高效地评估采矿废物坝的重金属提供了一种有利的替代方法。
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引用次数: 0
Reconstructing the Paleoenvironmental Evolution of Lake Kolon (Hungary) through Integrated Geochemical and Sedimentological Analyses of Quaternary Sediments 通过第四纪沉积物的地球化学和沉积学综合分析重建匈牙利科伦湖的古环境演化
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-07-03 DOI: 10.3390/quat6030039
Tamás Zsolt Vári, S. Gulyás, P. Sümegi
Lake Kolon (Hungary), situated in the middle of the Turjánvidék area between the saline lakes of the Danube valley and the Homokhátság, is one of the most significant natural aquatic habitats in the Danube–Tisza Interfluve region. The central question of this study is how the lake changed, and how environmental factors and human activities have influenced these paleoenvironmental changes in Lake Kolon. A multiproxy analysis of a core sequence (loss on ignition, grain size, magnetic susceptibility, and geochemistry) provided crucial insights. Notably, correlations are observed in the following relationships: (1) clay, organic matter, and elements derived from organic sources, such as Na, K, and Zn; (2) MS, sand, inorganic matter, and elements originating from inorganic sources, such as Fe, Al, Ti, Na, K, and P; and (3) carbonate content and elements originating from carbonate sources, such as Ca and Mg. The lake’s paleoenvironment underwent significant changes in the past 27,000 years. Late-Pleistocene wind-blown sand provided the bottom for an oligotrophic lake (17,700 BP), followed by a calcareous mesotrophic Chara-lake phase (13,800 BP). Peat accumulation, along with the eutrophic lake phase, began at the Pleistocene–Holocene boundary around 11,700 BP. From 10,300 BP, with the emergence of an extended peatland phase, the percentage of organic matter (peat) increased significantly. Anthropogenic changes occurred from around 9000–8000 BP due to the different emerging cultures in the Carpathian basin, and from 942–579 BP due to the Hungarian settlements and activity nearby, respectively.
Kolon湖(匈牙利)位于Turjánvidék区域的中部,介于多瑙河流域的盐湖和Homokhátság之间,是多瑙河- tisza交汇处地区最重要的天然水生栖息地之一。本研究的核心问题是湖泊是如何变化的,以及环境因素和人类活动是如何影响可隆湖这些古环境变化的。对岩心序列的多代理分析(着火损失、粒度、磁化率和地球化学)提供了重要的见解。值得注意的是,在以下关系中观察到相关性:(1)粘土,有机质和来自有机来源的元素,如Na, K和Zn;(2)质、砂、无机物和来自无机来源的元素,如Fe、Al、Ti、Na、K和P;(3)碳酸盐含量和碳酸盐源元素,如Ca和Mg。在过去的27000年里,湖泊的古环境发生了重大变化。晚更新世风沙为低营养湖泊(17700 BP)提供了底部,随后是钙质中营养Chara-lake阶段(13800 BP)。泥炭堆积与富营养化湖泊阶段开始于更新世-全新世边界,大约在11700 BP左右。从10300 BP开始,随着泥炭地扩展期的出现,有机质(泥炭)比例显著增加。由于喀尔巴阡盆地不同的新兴文化,人类活动的变化分别发生在大约9000-8000 BP和942-579 BP之间,这是由于匈牙利人的定居和附近的活动。
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引用次数: 1
Development History of the Loess–Paleosol Profiles of Pécel, Kisdorog and Bonyhádvarasd, Hungary 黄土的发展史——匈牙利佩塞尔、基斯多罗格和Bonyhádvarasd的古土壤剖面
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-07-02 DOI: 10.3390/quat6030038
László Makó, P. Cseh, B. Nagy, P. Sümegi, D. Molnár
This study covers the examination of four loess–paleosol profiles in Hungary through grain size composition, organic matter, carbonate content and magnetic susceptibility measurements. One of the profiles (with a thickness of 25.72 m) can be found in the Gödöllő hills, on the border of town Pécel, and the other three profiles (Kisdorog-West—5.60 m, Kisdorog-East—6.40 and Bonyhádvarasd—8.16 m) are located in the Tolna hills of the Transdanubia region. The sections were continuously sampled with an interval of 4 cm. The same interval was also applied to the other three profiles. During the field exploration of the Pécel profile, we were able to study the complete loess wall, which was deposited on the sediment of the nearby Rákos stream. Based on the Ostracod fauna of the clay sediment beneath, the fluvial deposit can be considered as originating from the Upper Miocene. In the case of the Transdanubian sections, a significant change can be observed in the prevailing wind direction based on the grain size analyses. In addition, the results of magnetic susceptibility measurements suggest that the development of the Pécel profile took place during MIS 9–10, while the age of the three Transdanubian sections can be assumed to be the MIS 2–4.
本研究通过粒度组成、有机质、碳酸盐含量和磁化率测量对匈牙利四个黄土-古土壤剖面进行了研究。其中一条剖面(厚度为25.72米)位于psamucel镇边界的Gödöllő山上,另外三条剖面(kisdoroge - west - 5.60米,kisdoroge - east - 6.40米和Bonyhádvarasd-8.16米)位于外多瑙河地区的Tolna山上。每隔4 cm连续取样。同样的间隔也适用于其他三个概要文件。在psamucel剖面的野外勘探中,我们能够研究完整的黄土墙,它沉积在附近Rákos河的沉积物上。根据下面粘土沉积物的介形虫动物群,可以认为河流沉积物起源于上中新世。在跨多瑙河段的情况下,根据粒度分析,可以观察到盛行风向的显著变化。此外,磁化率测量的结果表明,psamucel剖面的发展发生在MIS 9-10期间,而三个跨多瑙河剖面的年龄可以假定为MIS 2-4。
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引用次数: 0
Late Pleistocene to Holocene Palaeohydrological History of the Thermal-Spring-Fed Lake Pețea (NW Romania) Revealed by Radiocarbon Dating and Complex Sedimentological Investigations 放射性碳定年和复杂沉积学研究揭示了Pețea湖(罗马尼亚西北部)温泉补给的晚更新世至全新世古水文史
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-06-12 DOI: 10.3390/quat6020037
S. Gulyás, P. Sümegi
Understanding sedimentation processes in response to past hydrogeological and climatic changes and capturing millennial-scale variations is a key focus of lacustrine paleoenvironmental research. This study presents the first high-resolution chronology and sedimentary data for the small thermal-spring-fed Lake Pețea, NW Romania, and unravels the evolutionary history of the lake harboring a unique endemic fauna. Its small size and single source of water make it particularly sensitive to hydrological changes. In the recent past, over-exploitation of the thermal water has led to the complete drying up of the lake and the extinction of its fauna. Nevertheless, past spatio-temporal variation of environmental factors, in particular the fluctuation of lake levels and water temperature, must have had a significant impact on the survival and evolution of the endemic mollusk fauna. This fact makes this study particularly important. Based on our results, a three-stage sedimentary evolution occurred, mainly controlled by major climate-driven hydrological changes also seen in regional records, i.e., 17.5–14.5 ka shallow eutrophic lake, 14.5–5.5 ka oligotrophic carbonate-rich lake, and 5.5–0.5 ka shallow eutrophic lake. A major lowstand at 11.7–10.2 ka due to drier climate was followed by progressively rising water levels up to 5 ka followed by a drop. The main control on lake level fluctuations and sedimentary phases was the varying input of thermal water due to recurring increased/decreased recharge of the underground shallow karst water system. The driving factor of thermal water discharge was different during the Late Glacial than the Holocene. It was the warming of the climate at 14.5 ka cal BP and melting of regional ice sheets in addition to increased precipitation that created an oligotrophic lake by recharging the underground thermal water system. Conversely, during the Holocene, increasing/decreasing moisture availability driven by major climate forcings was in control of thermal water recharge, erosion, and fluctuating lake levels.
了解沉积过程对过去水文地质和气候变化的响应,并捕捉千年尺度的变化,是湖泊古环境研究的重点。这项研究首次提供了罗马尼亚西北部小型温泉湖Pețea的高分辨率年表和沉积数据,并揭示了该湖拥有独特特有动物群的进化史。它体积小,水源单一,对水文变化特别敏感。在最近的一段时间里,对热水的过度开发导致了湖泊的完全干涸和动物群的灭绝。然而,过去环境因素的时空变化,特别是湖泊水位和水温的波动,一定对当地软体动物的生存和进化产生了重大影响。这一事实使得这项研究显得尤为重要。根据我们的研究结果,发生了三阶段的沉积演化,主要受区域记录中也可见的主要气候驱动的水文变化控制,即17.5–14.5 ka浅富营养化湖、14.5–5.5 ka贫营养化富碳酸盐湖和5.5–0.5 ka浅富养化湖。由于气候干燥,11.7–10.2 ka的主要低点随后水位逐渐上升,最高可达5 ka,随后水位下降。湖泊水位波动和沉积相的主要控制因素是地下浅层岩溶水系统补给量的反复增加/减少导致热水输入的变化。晚冰川期热水排放的驱动因素与全新世不同。正是14.5卡BP的气候变暖和区域冰盖的融化,加上降水量的增加,通过补给地下热水系统,形成了一个贫营养湖泊。相反,在全新世期间,主要气候强迫导致的水分可利用性的增加/减少控制了热水补给、侵蚀和湖泊水位的波动。
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引用次数: 1
Assessment of Pollen Representation in NW Italy (Liguria and Piedmont) 意大利西北部利古里亚和皮埃蒙特地区花粉代表性评价
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-06-09 DOI: 10.3390/quat6020036
D. Attolini, Francesco Ciani, Mariangela Guido, C. Montanari
This research focuses on the recent pollen image of several vegetation types in NW Italy. In 201 arboreal, shrubby, and herbaceous plant populations, pollen samples were taken from moss polsters, and the corresponding vegetation was recorded using the phytosociological method. Since studies on recent pollen rain in the Mediterranean mountains and coast are rare, this research aims to provide new data and tools to better interpret fossil pollen spectra. Pollen analysis provided data for the comparison between surface spectra and vegetation. Davis indices, fidelity, dispersion, and the relation with vegetation data were calculated for each taxon, and PCA was carried out. Most vegetation types are identifiable through the taxa dominating the pollen spectra, as frequently happens in woodlands (e.g., beech woods, chestnut woods, etc.). Characterizing shrubland and certain tree-dominated vegetation types (e.g., Larix forests) through pollen data is more complex. In this regard, Davis indices are particularly useful for identifying pollen/plant association, over- and underrepresentation of pollen, and taxa indicating vegetation types. Pollen threshold values were calculated which allow the assessment of the local presence of a plant. Overall, the achieved results partially confirm those of previous research carried out in the region, greatly expanding the comparisons between several different plant communities and the database in view of future sharing through the EMPD.
本研究的重点是意大利西北部几种植被类型的花粉图像。在201个乔木、灌木和草本植物种群中,从苔藓虫身上采集了花粉样本,并使用植物社会学方法记录了相应的植被。由于对地中海山脉和海岸最近花粉雨的研究很少,本研究旨在为更好地解释化石花粉光谱提供新的数据和工具。花粉分析为地表光谱和植被之间的比较提供了数据。计算了每个分类单元的Davis指数、保真度、离散度以及与植被数据的关系,并进行了主成分分析。大多数植被类型都可以通过花粉光谱中占主导地位的分类群来识别,这在林地(如山毛榉林、栗子林等)中经常发生。通过花粉数据来描述灌木林和某些树木主导的植被类型(如落叶松林)更为复杂。在这方面,Davis指数对于识别花粉/植物组合、花粉代表性过高和过低以及指示植被类型的分类群特别有用。计算花粉阈值,从而可以评估植物的局部存在。总的来说,所取得的结果部分证实了之前在该地区进行的研究,极大地扩大了几个不同植物群落与数据库之间的比较,以便于未来通过EMPD共享。
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引用次数: 0
The Role of Past Climatic Variability in Fluvial Terrace Formation, a Case Study from River Mureş (Maros), Romania 过去气候变率在河流阶地形成中的作用——以罗马尼亚穆雷伊河(马罗斯)为例
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-06-02 DOI: 10.3390/quat6020035
Tamás Bartyik, P. Urdea, T. Kiss, Alexandru Hegyi, G. Sipos
Fluvial terrace formation is a complex process governed by the interplay of climatic and tectonic forcings. From a climatic perspective, an incision is usually related to climatic transitions, while valley aggradation is attributed to glacial periods. We have reconstructed the formation of Late Pleistocene fluvial terraces along the middle, mountainous section of a temperate zone river (Mureş/Maros) in order to identify the roles of different climatic periods and potential vertical displacement in terrace development. Investigations were based on two profiles representing two different terrace levels. The profiles were subjected to sedimentological and detailed geochronological analyses using optically stimulated luminescence (OSL). The results indicated that the investigated terraces represent different incision events coinciding with climatic transition periods. However, a joint MIS 3 valley aggradation period can be identified at both of them. Thus, the relatively mild but highly variable climate of the MIS 3 facilitated sediment mobilization from upland catchments. On the other hand, there is no evidence of aggradation under the cold and stable climate of MIS 2. However, the tectonic setting favours incision at the site. Based on our results, we concluded that the timing of the main events was controlled primarily by climatic forcing. The terrace formation model recognised might also be applied at other rivers in the region.
冲积阶地的形成是一个复杂的过程,受气候和构造作用力的影响。从气候角度来看,切口通常与气候转变有关,而山谷沉积则归因于冰川期。我们重建了沿温带河流(Mureş/Maros)中部山区的晚更新世河流阶地的形成,以确定不同气候时期和潜在垂直位移在阶地发育中的作用。调查基于代表两个不同阶地水平的两个剖面。利用光学激发发光(OSL)对剖面进行了沉积学和详细的地质年代分析。研究结果表明,所调查的阶地代表了与气候过渡期相吻合的不同切割事件。然而,在这两处都可以确定MIS 3河谷的联合沉积期。因此,MIS 3相对温和但高度多变的气候有助于从高地集水区调动沉积物。另一方面,在MIS 2寒冷稳定的气候条件下,没有沉积的证据。然而,构造环境有利于在现场进行切割。根据我们的结果,我们得出结论,主要事件的发生时间主要由气候强迫控制。已识别的阶地形成模型也可应用于该地区的其他河流。
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引用次数: 0
Plants, Fire and Landscape at the Prehistoric Pile-Dwelling Village of Palù di Livenza (PaluON1), UNESCO Site in the Italian Alps 史前堆居村Palù di Livenza (PaluON1)的植物、火和景观,联合国教科文组织在意大利阿尔卑斯山的遗址
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-06-01 DOI: 10.3390/quat6020034
Jessica Zappa, N. Degasperi, M. Bassetti, A. Florenzano, P. Torri, Gabriel Servera-Vives, A. Mercuri, R. Micheli
This paper presents palynological data obtained from a trench excavated at the Neolithic pile-dwelling archaeological site of Palù di Livenza (northeastern Italy). The site is in a wetland located in a tectonic basin at the foot of the Cansiglio plateau, crossed by the Livenza river. Environmental conditions have made this wetland a suitable area for settlements since prehistoric times. Thanks to the peaty sediments that characterise the area, archaeological materials and botanical remains have been exceptionally well preserved. Their study has shed light on a Neolithic pile-dwelling settlement that developed in various phases between c. 6350 and 5600 cal BP (c. 4400 and 3650 BC), and has also allowed for a detailed environmental reconstruction of the surrounding environment. A vertical sequence of 20 samples was analysed to study pollen, non-pollen palynomorphs and microcharcoals. An age-depth model was performed based on three radiocarbon dates. The palynological analysis provided insight into the response of vegetation to environmental changes caused by both climatic fluctuations and human pressure. In this sense, it was possible to highlight differences in vegetation cover, some fires, the use of woody resources, the spread of cereal fields, as well as the presence of other cultivated plants and plant processing by the people within the village.
本文介绍了从意大利东北部Palúdi Livenza新石器时代桩居考古遗址挖掘的一条沟渠中获得的孢粉学数据。该场地位于坎西格里奥高原脚下的一个构造盆地中的湿地中,与Livenza河交叉。自史前时代以来,环境条件使这片湿地成为适宜定居的地区。由于该地区特有的泥炭沉积物,考古材料和植物遗迹保存得异常完好。他们的研究揭示了新石器时代的桩居定居点,该定居点在公元前6350年至5600年(公元前4400年至3650年)的各个阶段发展,并允许对周围环境进行详细的环境重建。对20个样本的垂直序列进行了分析,以研究花粉、非花粉花粉形态和微珊瑚。基于三个放射性碳年代进行了年龄深度模型。孢粉学分析深入了解了植被对气候波动和人类压力引起的环境变化的反应。从这个意义上讲,可以强调植被覆盖的差异、一些火灾、木质资源的使用、麦田的扩展,以及村庄内其他种植植物和植物加工的存在。
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引用次数: 0
An Assessment of Soil Phytolith Analysis as a Palaeoecological Tool for Identifying Pre-Columbian Land Use in Amazonian Rainforests 土壤植物岩分析作为识别前哥伦布时期亚马逊雨林土地利用的古生态工具的评价
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-05-11 DOI: 10.3390/quat6020033
James Hill, S. Black, A. Araujo-Murakami, R. Boot, R. Brienen, T. Feldpausch, John Leigue, Samaria Murakami, A. Monteagudo, G. Pardo, M. Peña-Claros, O. Phillips, M. Toledo, V. Vos, P. Zuidema, F. Mayle
Phytolith analysis is a well-established archaeobotanical tool, having provided important insights into pre-Columbian crop cultivation and domestication across Amazonia through the Holocene. Yet, its use as a palaeoecological tool is in its infancy in Amazonia and its effectiveness for reconstructing pre-Columbian land-use beyond archaeological sites (i.e., ‘off-site’) has so far received little critical attention. This paper examines both new and previously published soil phytolith data from SW Amazonia to assess the robustness of this proxy for reconstructing pre-Columbian land-use. We conducted the study via off-site soil pits radiating 7.5 km beyond a geoglyph in Acre state, Brazil, and 50 km beyond a ring-ditch in northern Bolivia, spanning the expected gradients in historical land-use intensity. We found that the spatio-temporal patterns in palm phytolith data across our soil-pit transects support the hypothesis that pre-Columbian peoples enriched their forests with palms over several millennia, although phytoliths are limited in their ability to capture small-scale crop cultivation and deforestation. Despite these drawbacks, we conclude that off-site soil phytolith analysis can provide novel insights into pre-Columbian land use, provided it is effectively integrated with other land-use (e.g., charcoal) and archaeological data.
植物岩分析是一种成熟的考古植物学工具,为研究全新世亚马逊地区前哥伦布时期的作物种植和驯化提供了重要的见解。然而,它作为一种古生态工具在亚马逊地区的使用还处于起步阶段,而且它在重建哥伦布发现前的考古遗址(即“非遗址”)以外的土地利用方面的有效性到目前为止还没有受到多少批评。本文研究了来自西南亚马逊地区的新的和以前发表的土壤植物岩数据,以评估这一替代指标在重建前哥伦布时期土地利用方面的稳健性。我们通过在巴西阿克里州的一个地理图形外辐射7.5公里的非现场土壤坑和在玻利维亚北部的一个环形沟渠外辐射50公里的土壤坑进行了研究,跨越了历史上土地利用强度的预期梯度。我们发现,在我们的土壤坑样带中,棕榈植物岩数据的时空模式支持了一种假设,即前哥伦布时代的人们在几千年的时间里用棕榈树丰富了他们的森林,尽管植物岩在捕捉小规模作物种植和森林砍伐方面的能力有限。尽管存在这些缺陷,但我们得出结论,如果将非现场土壤植物岩分析与其他土地利用(如木炭)和考古数据有效结合起来,可以为前哥伦布时期的土地利用提供新的见解。
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引用次数: 1
Revisit the Medieval Warm Period and Little Ice Age in Proxy Records from Zemu Glacier Sediments, Eastern Himalaya: Vegetation and Climate Reconstruction 从喜马拉雅东部泽姆冰川沉积物的代用记录中重新审视中世纪温暖期和小冰期:植被和气候重建
IF 2.3 Q2 GEOSCIENCES, MULTIDISCIPLINARY Pub Date : 2023-05-09 DOI: 10.3390/quat6020032
Nivedita Mehrotra, N. Basavaiah, Santosh K. Shah
The Late Holocene fossil pollen records from the Zemu glacier, located in Yabuk, North Sikkim, in the eastern Himalayas, effectively generated quantitative climate reconstructions based on the transfer function model. The transfer function model was developed by establishing a modern pollen–climate calibration set from the temperate alpine belt of North Sikkim. A redundancy analysis was carried out to detect the pattern of variation of climatic variables in the modern pollen datasets. The mean annual precipitation (MAP) and mean temperature of the warming month (MTWA) had the strongest influence on the composition of the modern pollen samples among the climatic variables considered in the analysis. Proxy data in the form of fossil pollen records were analyzed for reconstructing past climate based upon the relationships between modern pollen vegetation assemblages and climatic patterns. Transfer functions for MAP and MTWA were developed with the partial least squares (PLS) approach, and model performance was assessed using leave-one-out cross-validation. The validated model was used to reconstruct MAP and MTWA for the last 2992 cal years BP (1042 BC) in North Sikkim. The variability observed in the reconstructions was analyzed for past global climatic events. It was further compared with the available regional and hemispheric proxy-based climate reconstructions. The reconstructions captured comparable Medieval Warm Period (MWP) and Little Ice Age (LIA)-like events from the Zemu glacier region. The fossil pollen data and climate reconstructions were further compared with the mineral magnetism data of the subsurface sediment profile.
喜马拉雅东部锡金北部Yabuk的Zemu冰川晚全新世花粉化石记录,有效地生成了基于传递函数模型的定量气候重建。通过建立锡金北部温带高寒带的现代花粉-气候定标集,建立了传递函数模型。对现代花粉数据集进行了冗余分析,以检测气候变量的变化模式。在分析中考虑的气候变量中,年平均降水(MAP)和暖月平均温度(MTWA)对现代花粉样品组成的影响最大。基于现代花粉植被组合与气候模式的关系,分析了以化石花粉记录为代表的代用数据,重建了过去的气候。采用偏最小二乘(PLS)方法建立MAP和MTWA的传递函数,并使用留一交叉验证评估模型性能。利用该模型重建了锡金北部近2992 cal年BP (1042 BC)的MAP和MTWA。对重建过程中观测到的变率进行了对过去全球气候事件的分析。并将其与现有的基于区域和半球代理的气候重建结果进行了比较。这些重建捕获了泽木冰川地区类似中世纪温暖期(MWP)和小冰期(LIA)的事件。将花粉化石资料和气候重建资料与地下沉积物剖面的矿物磁学资料进行了比较。
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引用次数: 0
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Quaternary
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