Allt Odhar and Dalcharn: Two pre-Late Devensian/Late Weichselian sites in northern Scotland     

M. J. C. Walker  J. W. Merritt  C. A. Auton  C. R. Coope  M. H. Field  H. Heijnis  B. J. Taylor 《第四纪科学杂志》1992,7(1):69-86

The lithostratigraphy and biostratigraphy of two sites (Allt Odhar and Dalcharn) in north-central Scotland are described, where pollen spectra of temperate affinity have been obtained from organic deposits that underlie till. The pollen record from Allt Odhar, in association with evidence from plant macrofossils and Coleoptera, shows the expansion of birch woodland and its eventual replacement by open grassland under a climatic regime slightly cooler than that prevailing in the northern highlands of Scotland at the present day. The organic sediments accumulated during an Early Devensian interstadial episode, which has been dated by the uranium series disequilibrium method to ca. 106 ka BP. Evidence for one and possibly two Devensian glaciations may be preserved at the site. The pollen record from Dalcharn, by contrast, reflects the middle and later stages of an interglacial cycle with the transition from pine forest to grassland. The overlying till sequence contains evidence of at least two separate glacial episodes. The age of the warm stage cannot be established precisely on present evidence, but there are indications that it may predate the last (Ipswichian) interglacial. These are the first sites from the mainland of Scotland to provide evidence of wooded conditions during interstadial and interglacial episodes of the Middle/Late Pleistocene.  相似文献   

Postglacial history of alder (Alnus glutinosa (L.) Gaertn.) in the British Isles     

Keith David Bennett  H. John B. Birks 《第四纪科学杂志》1990,5(2):123-133

Data from 92 postglacial pollen sequences are used to map the spread and increase of alder (Alnus glutinosa) across the British Isles between 9000 and 5000 years ago. The spread is found to be patchy and erratic in space and time. Consideration of the habitat requirements and reproductive ecology of alder suggest that it spread within Britain and Ireland after about 10 000 yr BP, when suitable habitat for it was scarce. Alder spread across most of Britain and Ireland early in the postglacial but only increased in abundance as (i) suitable habitat became available through changing sea levels, hydroseral successions, and floodplain development, and as (ii) rare weather events produced the necessary conditions for reproduction. Alder is unique among British and Irish trees in its requirement for a suitable habitat isolated among expanses of unsuitable habitats. Because of this, maps of its postglacial population spread and increase do not show the spatial coherence of maps for other forest tree taxa.  相似文献   

Stratigraphy and thermoluminescence dating of Late Glacial cover sand in Denmark     

Else Kolstrup  Rainer Grün  Vagn Mejdahl  Susan C. Packman  Ann G. Wintle 《第四纪科学杂志》1990,5(3):207-224

In western Jutland deposits with a texture and structure similar to Dutch cover sands have been found. Investigations have been carried out on the lithology and the lithostratigraphic sequences. Pollen analysis is used for biostratigraphic correlation, and ages have been obtained by the radiocarbon method as well as by thermoluminescence techniques using both quartz and eldspar. The five sites are presented separately and the data are integrated into a general stratigraphic outline of the Late Glacial cover-sand sequence in Jutland. During the latest part of the Upper Pleniglacial and the earliest Late Glacial, older cover-sand type was deposited. Locally this sediment was also deposited during the later parts of the Late Glacial. Younger cover-sand type was deposited primarily during the Early Dryas and Late Dryas, but some sand of this type was also laid down during the Allerød and the earliest Holocene. The palaeobotanical records are discontinuous, but plant growth was probably present throughout the Late Glacial; only during the Altered did the deposition of sand decrease long enough to allow a relatively stable vegetational development. The investigation shows that the sequence of events in Jutland is similar to the Dutch record.  相似文献   

Pollen Viability for Air Pollution Bio-Monitoring     

Elena Gottardini  Fabiana Cristofolini  Elena Paoletti  Paolo Lazzeri  Giancarlo Pepponi 《Journal of Atmospheric Chemistry》2004,49(1-3):149-159

Biological characterization of Corylus avellana L. and Pinus nigra L. pollen samples was carried out to determine the actual value of pollen as a bio-indicator of the effects of atmospheric pollution, using samples from plants naturally developed in sites controlled for air pollution. In Trentino (North Italy), we selected six stations at three different levels of air pollution, which are constantly monitored with automatic gauges by the Environmental Protection Agency of Trento.First results showed that pollen viability of both species, germinability and pollen tube length of P. nigra, were higher in areas with no road traffic compared to heavy traffic ones. Pollen viability of P. nigra was positively correlated to ozone (O₃) concentrations and altitude but negatively to sulphur dioxide (SO₂), particulate matter with a diameter less than 10 m (PM₁₀), nitrogen oxides (NO_x) and nitrogen dioxide (NO₂) concentrations.  相似文献   

Arctic-alpine brown soils as a source of palaeoenvironmental information: Further 14C dating and palynological evidence from Vestre Memurubreen,Jotunheimen, Norway     

John A. Matthews  Christopher J. Caseldine 《第四纪科学杂志》1987,2(1):59-71

¹⁴C dating and pollen analytical evidence is presented relating to the usefulness of arctic-alpine Brown Soils for palaeoenvironmental reconstruction. A present-day soil has been examined together with its continuation beneath the outermost ?Little Ice Age’? end moraine of the glacier Vestre Memurubreen at a location well above the tree-line in the mid-alpine belt of southern Norway. Fourteen ¹⁴C dates from chemically-fractionated soil samples, which range in age from 495 ± 55 ¹⁴C yr in the uppermost 1 cm to > 4000 ¹⁴C yr within 13 cm of the buried soil surface, demonstrate near-linear age/depth gradients in the palaeosol. Continuous development of the palaeosol over at least 5000 calendar yr prior to burial confirms that Vestre Memurubreen attained its Neoglacial maximum extent in the ?Little Ice Age’?. Pollen stratification in buried and unburied profiles indicates a single vegetation change from a low-alpine dwarf-shrub heath to a mid-alpine ?grass’? heath, reflecting an altitudinal lowering of vegetation belts and a possible climatic cooling of 2-4°C. Surface additions of allochthonous (aeolian) mineral particles appear to have contributed to soil development, whilst mixing processes have been relatively unimportant at this site. The immobilisation of resistant organic residues and the ineffectiveness of biological and chemical activity are major reasons for the preservation of a palaeoenvironmental record in these high altitude soils.  相似文献   

东昆仑华力西—印支期花岗岩组合及构造环境     

古凤宝  吴向农  姜常义 《青海国土经略》1996,(1)

本文采用花岗岩组合的研究方法,依据不同侵入体、不同单元相互间成因上的亲源性、空间共生性及构造环境的制约性,归属了十二个单元组合。将时空相互关联的单元组合归并为三种不同构造机制的花岗岩组合序列,并对其成因类型及系列作了论述。追踪研究了泥盆—石炭纪、二叠纪—中三叠世、中三叠世末—侏罗纪花岗岩源岩背景及成岩构造特点。  相似文献   

Modern pollen-rain characteristics of tall terra firme moist evergreen forest, southern Amazonia     

William D. Gosling  Francis E. Mayle  Timothy J. Killeen 《Quaternary Research》2005,64(3):284-297

The paucity of modern pollen-rain data from Amazonia constitutes a significant barrier to understanding the Late Quaternary vegetation history of this globally important tropical forest region. Here, we present the first modern pollen-rain data for tall terra firme moist evergreen Amazon forest, collected between 1999 and 2001 from artificial pollen traps within a 500 × 20 m permanent study plot (14°34′50″S, 60°49′48″W) in Noel Kempff Mercado National Park (NE Bolivia). Spearman's rank correlations were performed to assess the extent of spatial and inter-annual variability in the pollen rain, whilst statistically distinctive taxa were identified using Principal Components Analysis (PCA). Comparisons with the floristic and basal area data of the plot (stems ≥10 cm d.b.h.) enabled the degree to which taxa are over/under-represented in the pollen rain to be assessed (using R-rel values). Moraceae/Urticaceae dominates the pollen rain (64% median abundance) and is also an important constituent of the vegetation, accounting for 16% of stems ≥10 cm d.b.h. and ca. 11% of the total basal area. Other important pollen taxa are Arecaceae (cf. Euterpe), Melastomataceae/Combretaceae, Cecropia, Didymopanax, Celtis, and Alchornea. However, 75% of stems and 67% of the total basal area of the plot ≥10 cm d.b.h. belong to species which are unidentified in the pollen rain, the most important of which are Phenakospermum guianensis (a banana-like herb) and the key canopy-emergent trees, Erisma uncinatum and Qualea paraensis.  相似文献   

川北若尔盖高原玛曲-红原一带表土中孢粉组合的特征     

蔡遥  王燕  蒋复初  李朝柱 《地质力学学报》2007,13(4):333-339

通过对四川若尔盖高原玛曲—红原一带20个表土孢粉样的分析,研究了该区域表土孢粉组合与现代植被的关系。结果显示,玛曲—红原一带表土的孢粉组合基本反映了现代植被的整体特征,与现代植被在植被类型、植被带的空间排列、主要建群种属和优势种属等方面基本一致。依据孢粉的百分含量,可以划分为亚高山灌丛植被区,亚高山灌丛、亚高山草甸植被区和高寒草甸、草原植被区3个植被带。表土花粉的代表性因种属的不同而各有差异,松属和菊科花粉具超代表性,云杉属花粉的代表性较好,禾本科和莎草科具低代表性,而桦木属则不具有超代表性,可能与桦木属花粉不易搬运有关。3个植被区中的表土孢粉的种类、比例与现代植被均存在一定的差别,这可能与植被退化有关。  相似文献   

On age of Nazimovskaya and Khasan formations in the Paleogene succession of southwestern Primor’e     

B. I. Pavlyutkin  S. I. Nevolina  T. I. Petrenko  T. K. Kutub-Zade 《Stratigraphy and Geological Correlation》2006,14(4):444-457

Materials of previous studies and new original geological and paleobotanic data are used to substantiate synchronism (late Eocene) of the Khasan and Nazimovskaya formations, the key stratigraphic units of the Paleogene in Primor’e. Coal-bearing sediments of the units rest upon early-middle Eocene volcanics (Kraskino rhyolite tuffs, Zaisanovka basaltic andesites) being overlain by the lower Fatash Subformation of the lower Oligocene with flora of the Kraskino type. The Ust’-Davydovskaya Formation of the Rechnoi Peninsula (outskirts of Vladivostok) is the most probable analogue of the Khasan (=Nazimovskaya) Formation.  相似文献   

Mammal fauna first found in alluvial-speleogenic formations of the late Neopleistocene and Holocene, northern Urals, locality Cheremukhovo-1     

T. V. Strukova  O. P. Bachura  A. V. Borodin  V. V. Stefanovskii 《Stratigraphy and Geological Correlation》2006,14(1):91-101

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