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青藏高原东部地区晚新生代孢粉组合特征及其古地理意义 总被引:4,自引:1,他引:4
青藏高原东部晚新生代孢子花粉组合大致可分为三个组合两个亚组合。中新世组合主要以壳斗科,桦科以及榆科为主,并有大量的松科花粉。上新世以后组合则以壳斗科和松科花粉据优势,并有很多草本植物花粉。晚新生代孢粉植物群在本地区已经分出南北两个区系,反映了不同的气候特征或者不同的高度。青藏高原东部的孢粉资料显示本地区至少有两个成煤时期:中新世和上新世到早更新世。孢粉资料说明在中新世时青藏高原可能已经达到两千米高度。这个高度已经可以构成影响本地区气候特征的因素之一。青藏高原在晚新生代的抬升是我国季风气候和现代气候分区形成的一个很重要的因素。 相似文献
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科尔沁沙地麦里地区晚全新世植被演化 总被引:17,自引:0,他引:17
根据一个泥炭剖面高分辨率花粉资料序列,初步重建了科尔沁沙地麦里地区晚全新世的植被演化过程。在3100 a BP以前,该地以固定沙丘上生长的蒙古栎(Quercus mongolica Fisch.)等阔叶疏林为主;以后随着半固定沙丘和流动沙丘增多,蒿属(Artemisia L.)和藜科等草本植物逐渐增加,而固定沙丘上的阔叶树则趋于减少。在1000~660 a BP期间,麦里地区几乎所有沙丘植物都经历了繁盛生长,蒙古栎种群的扩大尤其显著。3100 a BP以来植被和沙丘的演化可能同人类活动影响有直接关系,而1000~660 a BP期间的植物繁盛则由生长季雨量增加引起。花粉统计分析还表明,在森林草原等生态过渡带,花粉浓度和花粉沉积率比花粉百分比更好地指示了植被演化过程。 相似文献
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唐古拉山地区渐新世孢粉植物群及其古植被、古气候 总被引:1,自引:0,他引:1
唐古拉山地区广泛出露早新生代陆相地层,较好地记录了青藏高原北部新生代地质构造演化与古环境变迁的过程.通过在该区1:25万地质调查对雅西措组上段进行孢粉分析表明,孢粉组合以裸子植物花粉为主要成分,地质时代为早-中渐新世.在此基础上划分了3个孢粉植物群-气候期,当时植被是以松科植物为主组成的针叶林植被,从早期到中期喜湿热的蕨类植物和落叶阔叶树种增多;气候从凉爽湿润的南温带→半湿润偏干的北亚热带→偏干的南温带的转变. 相似文献
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《微体古生物学报》2015,(1)
对四川盆地东北缘宣汉七里峡剖面须家河组进行了详细的孢粉学研究,发现丰富的孢粉化石,共计59属113种,其中包括蕨类植物孢子35属62种,裸子植物花粉22属47种,苔藓类植物孢子1属3种,以及藻类化石1属1种。据此建立一个孢粉组合,命名为Dictyophyllidites-Lunzisporites-Chasmatosporites组合(简称DLC组合),并进一步分为上、下两个亚组合。根据孢粉组合内一些重要分子的地质时代延限及与国内外有关孢粉组合的对比,提出其地质时代属于晚三叠世诺利期—瑞替期(Norian—Rhaetian)。该孢粉植物群反映了一个以蕨类植物的真蕨类、石松类和裸子植物的松柏类和苏铁类群等占主导且较为繁盛的植被面貌,揭示出温暖潮湿的亚热带—热带气候环境。 相似文献
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宁晋泊晚更新世孢粉组合及其古环境演变 总被引:4,自引:0,他引:4
宁晋泊是河北平原南部三大古湖群之一,通过LN42.5m厚沉积剖面的孢粉分析,获得古植物群演替达近20次,反映古气候变化具明显冷暖气候旋回5次以上,其中有2次寒冷期,3次湿暖期。结合6.4m以上~(14)C年龄数据推断计算晚更新世与全新世界线在7.5m,这一界线与孢粉植物群、古气侯与古环境等分异界线非常吻合。因此作者推断宁晋泊的形成、发展与消亡时代相应在晚更新世早期的温暖期,全新世高温期再次复兴,后被河流沉积物所掩埋而消亡形成洼地。 相似文献
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根据从印度库茂恩(Kumaun)喜马拉雅纳尼塔尔(Naini Tal)温带地区获得的85cm钻井的孢粉资料,恢复了1720+/-130年以来晚全新世古植被演变史,并推测了当地的古气候,当前孢粉资料说明了该地区当时发育有栎树混交林和波动的温暖润气候,孢粉组合序列的初始阶段,森林距沉积盆地较远,但是,由于气候变得更加温暖潮湿,森林也很快茂密起来,约1200年前,因气候恶化,森林变得稀疏,而在约124年前,气候再次转好,麦类及其他作物花粉资料证明农耕活动大约开始于1460年前左右。 相似文献
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河南义马地区晚三叠世—侏罗纪孢粉组合及其地质意义 总被引:3,自引:2,他引:3
重点讨论了谭庄组上段孢粉组合(包括1新种和1新组合);简要描述了侏罗纪义马组砾岩段孢粉组合。谭庄组上段的孢粉组合主要以具双气囊的松柏类花粉为优势(占孢粉总数的65%),同时又具许多晚三叠世的常见分子和孑遗分子Aratrisporites,Cuneisporites,Taeniasporites。该组合可与中国北方及欧洲晚三叠世孢粉组合进行对比。义马组砾岩段的孢粉组合系首次发现,以蕨类孢子为主(占孢粉总数62.9%),裸子植物花粉次之(占孢粉总数37%)。其中常见的类型为Classopollis,其时代为早侏罗世。 相似文献
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The change of vegetation in Maili region over the last 3 400 14C years has been reconstructed based on a high-resolution pollen record. It was thought that the contrast between arboreal and herb plants in different periods might well reflect the change in relative extent of the fixed sand dunes and active sand dunes, and the evolution history of the sand dunes could be thus investigated. Before 3 100 a BP, the sand dunes around Maili bog supported a denser vegetation, with Quercus mongolica Fisch., Tilia L., Ulmus L. as its dominating taxa. Declination of the open forest and increase of major herb taxa since 3 100 a BP suggest an increasing area of semi-fixed and partly active sand dunes mainly supporting Artemisia L. and Chenopodiaeeae. Such a changing process has generally been continued through the last 3 000 years. However, the period from 1 000 a BP to 660 a BP was unique in that it witnessed a lush growth of nearly all of the taxa in the region, with the expanding of Quercus mongolica population being especially obvious. The desertification process starting at 3 100 a BP ceased during that time, and the different types of sand dunes were supporting a much denser vegetation covered in the period than any others. 相似文献
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The northern slopes of central Tianshan Mountains in Xinjiang, northwestern China can provide an ideal database to research palaeoclimate as disturbance by human impact is relatively low and the vegetation zones reflect climatic gradients. In order to establish the correlation between modern climatic factors and surface pollen assemblages and to reconstruct palaeoclimate on the northern slope of central Tianshan Mountains, three Holocene sections in Daxigou, Huashuwozi and Sichanghu located at different elevations and vegetation zones were chosen for study. A total of 80 surface pollen samples in 86 vegetation quadrats were collected for pollen‐vegetation relationship analysis. The Warmth Index (WI) and Moisture Index (MI) were calculated based on averaged modern climate data during 1951 – 2000 at eight weather stations in the study area. Pollen percentages of Picea, Artemisia, Chenopodiaceae, Ephedra, and Tamarix, as well as A/C (Artemisia/Chenopodiaceae) and AP/NAP (arboreal/nonarboreal pollen) ratio were selected as pollen variables and WI and MI were chosen as climatic variables. The relationship between pollen percentages (Picea, Artemisia, Chenopodiaceae and Tamarix), A/C, AP/NAP ratio, WI and MI values were estimated (95% confidence interval) using stepwise multiple linear regression analysis. WI and MI values for the three sections were calculated using these regression equations, and palaeoclimate for the study area could be reconstructed. The results showed periods of both cool‐humid and warm‐dry conditions on the northern slopes of Tianshan Mountain during the late Holocene. 相似文献
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A new pollen record from Lago di Vico (core V1) provides fundamental new information towards reconstruction of flora and vegetation history in central Italy during the last 90 000 years. The chronological framework is secured by seventeen AMS14C dates, one40Ar/39Ar date and tephra analyses. At the base of the pollen record, i.e. shortly after the40Ar/39Ar date 87 000±7000 B.P., three phases with significant expansion of trees are recorded in close succession. These forest phases, which stratigraphically correspond to St Germain II (and Ognon?) and precede pleniglacial steppe vegetation, are designated by the local names Etruria I, Etruria II and Etruria III. During the pleniglacial, a number of fluctuations of angiosperm mesophilous trees suggest the presence of tree refugia in the area. The lowest pollen concentration values are recorded at ca. 22 000 B.P. which corresponds with other pollen records from the region. The late-glacial is characterized by an expansion in the arboreal pollen curves that is less pronounced, however, than in other pollen profiles from Italy. The Holocene part of the profile is consistently dominated by deciduous oak pollen. No major changes in arboreal pollen composition are recorded but several marked and sudden declines of the tree pollen concentration suggest that the forest cover underwent dramatic changes. Clear evidence for human impact is recorded only when cultivated crops became important which dates to ca. 2630±95 B.P. 相似文献
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香港壕涌遗址孢粉、植硅石组合及其环境考古 总被引:3,自引:1,他引:3
香港壕涌遗址孢粉、植硅石组合表明:自新石器时期以来该遗址周围植被以热带-亚热带蕨类植物为主;草本植物以禾本科、莎草、藜科等主为;在遗址附近的高地及山坡上生长了常绿阔叶林,其成分包括:阿丁枫香属(Altingia)、栲属(Castanopsis )、常绿栎(evergrenn Quercus)、棕榈(Palmae)等;植被面貌是人类活动干扰的结果。新石期时期,遗址受海水影响,人类活动以采集、捕捞为主;唐宋时期,禾本科花粉及典型水稻硅酸体的大量出现,反映了稻作农业的发展及人类生存方式的改变。 相似文献
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Vania Stefanova Maria Lazarova Herbert E. Wright 《Vegetation History and Archaeobotany》2006,15(4):333-343
The Late Glacial and early-Holocene vegetational history of a newly dated pollen and macrofossil diagram from Besbog, a cirque lake at 2250 m just above the forest limit in the Pirin Mountains of southwestern Bulgaria, is compared with a newly dated pollen diagram for the mire Shiroka Polyana at 1400 m in the conifer forest of the nearby Rhodope Mountains in order to investigate the chronology of major changes in the vegetation at different elevations. In the Lake Besbog record the non-arboreal pollen assemblage of the Late Glacial changed abruptly to that of Betula, Quercus and other deciduous types. The date for this change is about 11.6 ka cal b.p. The Quercus assemblage may be composed of pollen blown from intermediate elevations, to which deciduous forest had expanded because of higher summer temperatures related to high summer insolation. At Shiroka Polyana (1400 m) in the modern conifer belt, a similar change did not occur until about 8.8 ka cal b.p. The persistence of the dry steppe or steppe forest in the early Holocene at this lower site can also be attributed to high summer insolation. Thus as atmospheric temperature increased at the end of the Late Glacial, deciduous forests expanded first at intermediate elevations in the Pirin Mountains and only later in the Rhodope Mountains at lower elevations as summer insolation decreased. 相似文献
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Gabriela Domínguez-Vázquez Gerald Alexander Islebe 《Vegetation History and Archaeobotany》2008,17(3):327-333
A 3.4 m core was obtained for paleoecological analysis from Naja Lake in the Lacandon region of southeastern Mexico. This
is the first study of the Lacandon area aimed at reconstructing late Holocene environmental history. The basal section of
the core yielded an AMS date of 2020 14C years b.p. The Naja pollen record shows that the lower montane rain forest characterized by Moraceae, Mimosoideae, Leguminosae and
Combretaceae/Melastomataceae, coexisted with a pine-oak forest throughout the late Holocene. No Zea mays pollen was found during routine pollen counts, but the presence of both secondary pollen taxa and abundant charcoal particles
suggest some degree of regional human impact. A marked increase in Pinus pollen, together with a reduction in lower montane rain forest taxa, is interpreted as evidence for a strong, protracted
drought from 1260 to 730 14C years b.p. 相似文献
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Maria Eugenia De Porras Maria Virginia Mancini Aldo Raul Prieto 《Vegetation History and Archaeobotany》2009,18(3):235-244
Vegetation changes during the late Holocene are interpreted from four fossil pollen sequences from two caves at the Los Toldos
archaeological locality, Santa Cruz province, Argentina. Taphonomic processes are particularly taken into account in order
to analyze the effects on the fossil pollen records of biotic factors such as human occupation and animals, and abiotic ones
such as volcanic ash fall. Fossil pollen assemblages are interpreted using local modern pollen data. The main vegetation change
occurred at ca. 3750 uncal b.p., when a shrub steppe of Asteraceae subf. Asteroideae with Schinus, Ephedra frustillata and a high proportion of grasses was replaced by a shrub steppe of Colliguaja integerrima and Asteraceae subf. Asteroideae. This change is synchronous with an archaeological record change and could be related either
to moderate climatic variations or the effects of ash fall on the environment. Plant communities similar to the present-day
ones were established in the Los Toldos area from ca. 3750 uncal b.p. 相似文献
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C.A. Wright A. Dallimore R.T. Patterson 《Palaeogeography, Palaeoclimatology, Palaeoecology》2005,224(4):367-384
Paleontological studies of fish remains in laminated sediments provide a proxy relationship between fish populations and ocean climate. This study examines climate variability from approximately 500 y B.P. to 4000 y B.P. as recorded in fish remain abundances (primarily scales) collected from laminated sediments within Effingham Inlet on the west coast of Vancouver Island, British Columbia. The study also discusses technical issues involving fish remains from laminated sediments, including sampling resolution, sediment volume, identification of remains and appropriate abundance considerations.The dominant species in the assemblage include Northern anchovy and Pacific herring, with lesser percentage-abundances from rockfish, hake, elasmobranches and surfperch. The data indicate that Northern anchovy experienced a shift in scale deposition abundance at approximately 2800 y B.P. with not only a greater total abundance but also a greater consistency of deposition with time. Pacific herring underwent cyclical deposition that changed little through time. Statistical analysis reveals that none of these species is directly responding to climatic signals as indicated in the lithological and palynological record, but that this could have been partially due to the sampling resolution of the piston core. Analysis indicates a lack of correlation between the two dominant species, as might be expected on the basis of their opposing lifestyle strategies with respect to sea surface temperatures.With appropriate sampling strategies, paleohistorical fish remains from laminated sediments reflect changes in population structure and behaviour for some species, illustrate basic secondary trophic information, and provide potential clues to basin-scale oceanographic/climatological variability. 相似文献
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María José Gil García María Blanca Ruiz Zapata Juan Ignacio Santisteban Rosa Mediavilla Enrique López-Pamo Cristino José Dabrio 《Vegetation History and Archaeobotany》2007,16(4):241-250
The use of a high resolution pollen record in combination with geochemical data from sediments composed mainly of layers of
charophytes alternating with layers of vegetal remains plus some detrital beds permits the reconstruction of the environmental
evolution of the last 3000 years in an inland wetland of the Mediterranean domain, thus introducing a new climatic dataset
for the Late Holocene. Hydrological fluctuations, reflected in the relationship between emerged and aquatic vegetation and
inorganic and organic C and N changes, can be related to aridity or humid phases, while relations among arboreal taxa (Quercus and Pinus) and Artemisia are used as temperature indicators. Five climatic periods have been identified: a Subatlantic Cold Period (<150 b.c.), cold and arid; the Roman Warm Period (150 b.c.–a.d. 270), warmer and wetter; the Dark Ages (a.d. 270–a.d. 950), colder and drier; the Medieval Warm Period (a.d. 950–a.d. 1400), warmer and wetter; and the Little Ice Age (>a.d. 1400) indicated by a cooling and drying trend. Despite the lack of any direct evidence of human action, there are some episodes
related to deforestation during the Reconquista (Middle Ages) that mask the real climatic signal. 相似文献
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A pollen record of a Late Holocene sediment core from the Mexican Caribbean coast (Quintana Roo) shows the development and changes of a mangrove system. Humid conditions seem to have persisted for the period approximately 2500–1500 14C yr BP (pollen zone I), and mangrove Rhizophora mangle dominated with a good representation of elements from the nearby semi-evergreen tropical forest. During the period approximately 1500–1200 14C yr BP (pollen zone II) the mangrove Conocarpus erecta dominated. R. mangle almost disappeared and other taxa appeared, suggesting drier climatic conditions and generally more open vegetation. This dry period coincided with the period of the Maya cultural decline. The following period (pollen zone III, approximately 1200–1000 14C yr BP) was characterized by the recovery of R. mangle, indicating more humid conditions than in the preceding pollen zone. Pollen zone IV (approximately 1000 14C yr BP till present) suggests a drier period reoccuring with C. erecta; this marks the transition to present day conditions. 相似文献