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1.
A sedimentological and plant microfossil history of the Late Quaternary is preserved in two sediment cores from early Polynesian ditch systems on southern Aupouri Peninsula. The study places human activities into a geomorphological and ecological context and allows comparison of natural and anthropogenic effects on two different geological settings: a floodplain and a relatively closed peat swamp. The data fill part of the current gap in the environmental record from northern New Zealand, namely MIS 3 (57k–26k yr BP). There is evidence for an increase in fire frequency in the region after 40k 14C yr BP, suggesting a shift to drier (and cooler) conditions. Pollen records show that conifer‐hardwood forest dominated by podocarps (especially Dacrydium) prevailed prior to Polynesian arrival and deforestation within the last millennium, with Fuscopsora insignificant throughout. Both cores show sections with gaps in deposition or preservation, possible flood‐stripping of peat during the pre‐Holocene and mechanical disturbance by early Polynesians. The identification of prehistoric starch grains and other microremains of introduced Colocasia esculenta (taro) in both cores supports indirect evidence that the ditch systems of far northern New Zealand were used for the extensive cultivation of this crop. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
2.
《第四纪科学杂志》2008,23(1):no-no
Journal of Quaternary Science Published online 9 August 2007. DOI: 10.1002/jqs.1118 The above paper was incorrectly titled. The correct title should be: Comment: Middle Pleistocene sedimentation at Pakefield, Suffolk, England J. R. LEE, J. ROSE, I. CANDY and R. W. BARENDREGT (2006) Journal of Quaternary Science 21 : 155–179 The error will be corrected prior to print publication. 相似文献
3.
The Quaternary geological environment supplied mankind with a habitat and rich natural resources such as forest, meadow,
water, etc. Mankind has developed to modern civilization through a very long history. During the last 100 years the area of
desertification has been expanding, natural resources have been consumed, and eco-environments plundered. Mankind felled forests,
cultivated grassland, and increased farmland because of unceasing increasing population and the need for materials. In a period
of 50–100 years, mankind's destruction could change good meadow into desert. The following examples are evidence: Shangdu
grassland in Inner Mongolia and the west grassland of Jilin Province have been changing into desert rapidly. Two concepts
of destructive power (D) and bearing capacity (B) can be used to describe this process. When D<B, the ecosystem keeps good circulation, D=B, eco-balance reaches critical state, and D>B, ecosystem loses balance, the environment is destroyed and developed toward desert. The law of destructive power increasing
with time accords with logistic curves and can be expressed by a logistic model. Destructive power (D) increases with decrease of bearing capacity (B);D and B represent a reciprocal relation. With a logistic model the developing process of desertification can be studied and the developing
rate and strength of change can be forecasted.
Received: 20 July 1998 · Accepted: 1 December 1998 相似文献
4.
We have used digital photography, image analysis and measurements in the field to determine the growth rates of Quaternary corals in the Wakatobi Marine National Park, Indonesia, and compared them to growth rates of similar corals in the same area. In the Quaternary deposits it was possible to measure the growth rates of two massive coral genera Porites and Favites. For each genus, the corals reworked from better‐illuminated upslope environments had higher growth rates than the in situ fossil corals. The calculated radial growth rates for the in situ Porites are slightly lower than, but of the same order of magnitude as, the modern Porites growing in 10 m water depth at Hoga (10.04 ± 3.34 mm yr?1 ± 1 s.d.; n = 3) and Kaledupa (15.26 ± 4.83 mm yr?1 ± 1 s.d.; n = 3). Sedimentation rates and underwater visibility are inferred to have been similar in the fossil site to that at the modern Kaledupa site. Decreasing light penetration due to increased water depth is inferred to have been a major influence on growth rates. The in situ massive corals with good growth banding are inferred to have grown in a comparable environment to modern Kaledupa and Hoga. The study highlights that it is possible to compare coral growth rates, and their influencing parameters, from modern and well‐preserved ancient examples. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
5.
Recent writing in geography and its cognate disciplines suggests that the crisis of masculinity is in large part about the
marginalization of men. With this paper, we take this spatial metaphor to task using David Fincher's Fight Club as a foil against which we try to pin larger issues of masculinity and urban life. That Flight Club can be viewed as alienated men confronting their homosocial and homoerotic selves through laddish revolutionary pranks detracts
from its potential as a commentary on larger social tensions and contradictions. Men are simultaneously in the center and
at the margins of what Bourdieu describes as the habitus; they are simultaneously playful and despairing, they are simultaneously alienated and the purveyors of hegemonic order.
Fincher's movie engages these spatial metaphors and offers an opportunity to destroy the habitus, to change both masculinity
and culture.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
Sediments from Rapid Lake document glacial and vegetation history in the Temple Lake valley of the Wind River Range, Wyoming over the past 11,000 to 12,000 yr. Radiocarbon age determinations on basal detrital organic matter from Rapid Lake (11,770 ± 710 yr B.P.) and Temple Lake (11,400 ± 630 yr B.P.) bracket the age of the Temple Lake moraine, suggesting that the moraine formed in the late Pleistocene. This terminal Pleistocene readvance may be represented at lower elevations by the expansion of forest into intermontane basins 12,000 to 10,000 yr B.P. Vegetation in the Wind River Range responded to changing environmental conditions at the end of the Pleistocene. Following deglaciation, alpine tundra in the Temple Lake valley was replaced by a Pinus albicaulis parkland by about 11,300 14C yr B.P. Picea and Abies, established by 10,600 14C yr B.P., grew with Pinus albicaulis in a mixed conifer forest at and up to 100 m above Rapid Lake for most of the Holocene. Middle Holocene summer temperatures were about 1.5°C warmer than today. By about 5400 14C yr B.P. Pinus albicaulis and Abies became less prominent at upper treeline because of decreased winter snowpack and higher maximum summer temperatures. The position of the modern treeline was established by 3000 14 C yr B.P. when Picea retreated downslope in response to Neoglacial cooling. 相似文献
7.
Macrofossil, pollen, lithostratigraphy, mineral magnetic measurements (SIRM and magnetic susceptibility), loss‐on‐ignition, and AMS radiocarbon dating on sediments from two former crater lakes, situated at moderate altitudes in the Gutaiului Mountains of northwest Romania, allow reconstruction of Late Quaternary climate and environment. Shrubs and herbs with steppe and montane affinities along with stands of Betula and Pinus, colonised the surroundings of the sites prior to 14 700 cal. yr BP and the inferred climatic conditions were cold and dry. The gradual transition to open Pinus–Betula forests, slightly higher lake water temperatures, and higher lake productivity, indicate more stable environmental conditions between 14 700 and 14 100 cal. yr BP. This development was interrupted by cooler and drier climatic conditions between 14 100 and 13 800 cal. yr BP, as inferred from a reduction of open forests to patches, or stands, of Pinus, Betula, Larix, Salix and Populus. The expansion of a denser boreal forest, dominated by Picea, but including Pinus, Larix, Betula, Salix, and Ulmus started at 13 800 cal. yr BP, although the forest density seems to have been reduced between 13 400 and 13 200 cal. yr BP. Air temperature and moisture availability gradually increased, but a change towards drier conditions is seen at 13 400 cal. yr BP. A distinct decrease in temperature and humidity between 12 900 and 11 500 cal. yr BP led to a return of open vegetation, with patches of Betula, Larix, Salix, Pinus and Alnus and individuals of Picea. Macrofossils and pollen of aquatic plants indicate rising lake water temperatures and increased aquatic productivity already by ca. 11 800 cal. yr BP, 300 years earlier than documented by the terrestrial plant communities. At the onset of the Holocene, 11 500 cal. yr BP, forests dominated by Betula, Pinus and Larix expanded and were followed by dense Ulmus forests with Picea, Betula and Pinus at 11 250 cal. yr BP. Larix pollen was not found, but macrofossil evidence indicates that Larix was an important forest constituent at the onset of the Holocene. Moister conditions were followed by a dry period starting about 10 600 cal. yr BP, which was more pronounced between 8600 and 8200 cal. yr BP, as inferred from aquatic macrofossils. The maximum expansion of Tilia, Quercus, Fraxinus and Acer between 10 700 and 8600 cal. yr BP may reflect a more continental climate. A drier and/or cooler climate could have been responsible for the late expansion (10 300 cal. yr BP) and late maximum (9300 cal. yr BP) of Corylus. Increased water stress, and possibly cooler conditions around 8600 cal. yr BP, may have caused a reduction of Ulmus, Tilia, Quercus and Fraxinus. After 8200 cal. yr BP moisture increased and the forests included Picea, Tilia, Quercus and Fraxinus. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
8.
Lis Allaart Juliane Müller Anders Schomacker Tom A. Rydningen Lena Håkansson Sofia E. Kjellman Gesine Mollenhauer Matthias Forwick 《Boreas: An International Journal of Quaternary Research》2020,49(3):417-437
The deglaciation history and Holocene environmental evolution of northern Wijdefjorden, Svalbard, are reconstructed using sediment cores and acoustic data (multibeam swath bathymetry and sub-bottom profiler data). Results reveal that the fjord mouth was deglaciated prior to 14.5±0.3 cal. ka BP and deglaciation occurred stepwise. Biomarker analyses show rapid variations in water temperature and sea ice cover during the deglaciation, and cold conditions during the Younger Dryas, followed by minimum sea ice cover throughout the Early Holocene, until c. 7 cal. ka BP. Most of the glaciers in Wijdefjorden had retreated onto land by c. 7.6±0.2 cal. ka BP. Subsequently, the sea-ice extent increased and remained high throughout the last part of the Holocene. We interpret a high Late Holocene sediment accumulation rate in the northernmost core to reflect increased sediment flux to the site from the outlet of the adjacent lake Femmilsjøen, related to glacier growth in the Femmilsjøen catchment area. Furthermore, increased sea ice cover, lower water temperatures and the re-occurrence of ice-rafted debris indicate increased local glacier activity and overall cooler conditions in Wijdefjorden after c. 0.5 cal. ka BP. We summarize our findings in a conceptual model for the depositional environment in northern Wijdefjorden from the Late Weichselian until present. 相似文献
9.
The Quaternary deposits in the Galilee coastal plain comprise alternating calcareous sandstone, red loam, dark clay, and uncemented sand. The calcareous sandstone in the lower part of the sequence represents a Pliocene to early Pleistocene marine transgression, and is covered unconformably by the late Quaternary sequence. The base of this sequence has an estimated age of 500,000 yr. It is covered unconformably by marine calcareous sandstone in the west, which represents the global high sea-level stand of isotope stage 7.1, and is known as one of the “Tyrrhenian” events in the Mediterranean area. The overlying members represent the low sea-level stand of stage 6, the first a red paleosol indicating a relatively wet phase and the second an eolianite unit representing a drier phase. The eolianite forms longitudinal, subparallel ridges that formed contemporaneously. The overlying marine sandstone, which contains one of the diagnostic fossils of the “Tyrrhenian” events, the gastropodStrombus buboniusLMK, accumulated during the global high stand of stage 5.5. The last glacial period left no sedimentary record. The Holocene is represented by a marine clay unit that is covered by sand. The present study establishes a complete and detailed chronostratigraphic sequence for an eastern Mediterranean beach, which contains the gastropodS. buboniusLMK.S. buboniuson the Galilee coast is attributed to stage 5.5 and, therefore, establishes an east–west Mediterranean correlation, which can be used for linking Mediterranean events to paleo-sea levels and global climate changes. 相似文献
10.
A significant feature of Quaternary volcanism in New Zealand is the presence of several compact fields of monogenetic basaltic volcanism, in many respects comparable to back-arc volcanism of Japan and intra-plate volcanism in S.E. Australia. Volcanism in South Auckland between 1.56 m.y. (B.P.) and 0.51 m.y. has produced some 20 km3 of lava and scoria from at least 70 centres. Older lavas are alkalic (basanite and alkali-olivine basalt), and are associated with maars and small scoria cones and many contain mafic and ultramafic xenoliths and megacrysts. Younger subalkalic lavas (mainly transitional tholeiite) form large scoria cones with extensive lava aprons.Chemically and mineralogically the two types are distinct and represent separate parent magmas. Alkalic magma probably differentiated near source (<25 kb) by precipitation of kaersutite, olivine, and clinopyroxene. Subalkalic lavas were the product of more voluminous melting and observed differentiation trends may be due to Al-opx and subcalcic Al-cpx precipitation at 10 to 15 kb. Progressive melting of a mantle diapir rising through the low velocity zone can account for the temporal and petrologic relationships between the two magmas. 相似文献
11.
U‐series ages from thermal ionisation mass spectrometry are reported here for the raised coral reefs of Futuna Island, which lies adjacent to the eastern margin of the backarc Futuna Trough in south Vanuatu, southwest Pacific. U‐series ages from coral from the lowest raised reef indicate that its upper part is most likely to be ca 210 ka, whereas the most elevated raised reef has a likely age of ca 520 ka (range 600–440 ka). The inferred Pliocene‐Quaternary history for Futuna Island and the adjacent Futuna Trough is: (i) formation of the Pliocene—Early Quaternary basaltic‐andesite cone in a southeast part of the Vanuatu Island Arc; (ii) inception of the Futuna Trough (adjacent to the west margin of Futuna Island) since 1.8 Ma; (iii) subsequent uplift of the volcanic cone above sea‐level caused ～500 m of its upper part to be removed by marine erosion; (iv) the island then subsided and at least 160 m of limestone was deposited on the truncated cone; and (v) during the period 520 ka to ca 210 ka seven fringing reefs formed at the margin of the cone as the island was uplifted. Since ca 210 ka Futuna further subsided and, as a result, the post ca 210 ka history of the island is obscure. 相似文献
12.
BERND WAGNER OLE BENNIKE HOLGER CREMER MARTIN KLUG 《Boreas: An International Journal of Quaternary Research》2010,39(3):492-504
Wagner, B., Bennike, O., Cremer, H. & Klug, M. 2010: Late Quaternary history of the Kap Mackenzie area, northeast Greenland. Boreas, Vol. 39, pp. 492–504. 10.1111/j.1502‐3885.2010.00148.x. ISSN 0300‐9483. The Kap Mackenzie area on the outer coast of northeast Greenland was glaciated during the last glacial stage, and pre‐Holocene shell material was brought to the area. Dating of marine shells indicates that deglaciation occurred in the earliest Holocene, before 10 800 cal. a BP. The marine limit is around 53 m a.s.l. In the wake of the deglaciation, a glaciomarine fauna characterized the area, but after c. one millennium a more species‐rich marine fauna took over. This fauna included Mytilus edulis and Mysella sovaliki, which do not live in the region at present; the latter is new to the Holocene fauna of northeast Greenland. The oldest M. edulis sample is dated to c. 9500 cal. a BP, which is the earliest date for the species from the region and indicates that the Holocene thermal maximum began earlier in the region than previously documented. This is supported by driftwood dated to c. 9650 cal. a BP, which is the earliest driftwood date so far from northeastern Greenland and implies that the coastal area was at least partly free of sea ice in summer. As indicated by former studies, the Storegga tsunami hit the Kap Mackenzie area at c. 8100 cal. a BP. Loon Lake, at 18 m a.s.l., was isolated from the sea at c. 6200 cal. a BP, which is distinctly later than expected from existing relative sea‐level curves for the region. 相似文献
13.
14.
Laura C. Bishop Lawrence Barham Peter W. Ditchfield Sarah Elton William E. H. Harcourt‐Smith Peter Dawkins 《第四纪科学杂志》2016,31(3):178-190
This paper describes a large collection of Quaternary fossil fauna from the Luangwa Rift Valley, Zambia. Stone Age artefacts have been recovered from stratified fluvial contexts, but no in situ fossil faunas have yet been recovered. We report on 500 fossil specimens collected from the surface of point bars exposed seasonally along the banks of the main Luangwa River channel. We used non‐destructive X‐ray fluorescence analysis of the fossils' chemical signatures to determine whether they derive from one or many primary contexts, and the relationship between chemical signature and state of preservation. Specimens are identified to taxon (genus) to reconstruct palaeoenvironments and biochronology. A relatively wide range of taxa is identified, including a fossil hominin talus, described here. None of the fossils is positively attributable to extinct species, except a femur of an extinct Theropithecus reported in 2003. Although no additional extinct taxa were identified, some of the remains were attributable to genera that are not currently found in this region. The results suggest that most of the assemblage derives from sediments which are Middle Pleistocene or later, and that past environments in the Luangwa Valley may have differed from the habitat availability found today. 相似文献
15.
16.
Groundwater bearing alluvial units in the seismically active settlement areas may bring out probable damage on the urban and
built environment due to liquefaction. Bolu settlement area and surroundings are located in the North Anatolian Fault Zone.
Geotechnical boreholes were drilled in order to determine the distribution of the geological units, to obtain representative
soil samples and to measure groundwater level. Quaternary aged alluvium is the main geological unit in the South of study
area. Stiffness and consistency of the soils were determined by Standart penetration test. P and S wave velocities of soil
have been measured along the seismic profiles. The index and physical properties of the samples have also been tested in the
laboratory. Liquefaction potential and safety factor of the sandy levels in Quaternary aged alluvium were investigated by
different methods based on SPT and V
s. Liquefaction seems to be a significant risk in case of an earthquake with a
max = 0.48 g and M
w
= 7.5 at different levels of the boreholes. This situation may bring out environmental problems in the future. 相似文献
17.
Randomisation tests on boulder weathering data distinguish moraines of four different ages in the Rongbuk Valley, all deposited by valley glaciers flowing northward into Tibet from the Himalaya. Lichenometry utilising subgenus Rhizocarpon distinguishes two groups of moraines, those <100 yr old and those older than several thousand years. The degree of soil development has a similar, limited utility in relative-age dating these moraines. The radiocarbon ages of calcium carbonate coatings in the lower horizons of moraine soils provide minimum-limiting ages of 1900 yr BP for the penultimate advance of the Rongbuk glacier (Samdopo moraine) and 9500 yr BP for the Rongbuk moraine, the moraine suggested by previous workers to represent the last glacial maximum. Equilibrium-line depression associated with the Rongbuk moraine probably was slight, <200 m. The small magnitude of this depression relative to glaciers in other mountain ranges could relate to a weakening of the monsoon in full glacial times, recent tectonic uplift, and/or to the insensitivity of these high-altitude glaciers to lowering temperatures in the rain shadow of Mount Everest. 相似文献
18.
Ivan Madirazza 《International Journal of Earth Sciences》1968,57(3):1034-1066
This paper deals with two salt domes, Mønsted and Sevel, located in northern Jutland, and is primarily concerned with the problem of Quaternary salt tectonics and its possible relationship to the Quaternary morphology.Geological mapping of the two areas during the summers of 1965 and 1966 included a detailed surveying by means of a theodolite of a stream valley extending over the north-eastern part of Mønsted salt dome and of two valleys in the southern part of Sevel salt dome. In the Mønsted area extensive use of aerial photographs was made.In the light of the results of the geological study, an interpretation of the available geophysical data — in the case of Mønsted both gravimetric and magnetic — is attempted.
Zusammenfassung Die Salzstöcke Mønsted und Sevel in Nordjütland werden untersucht. Es wird versucht in beiden Gebieten eine Beziehung zwischen Quartär-Morphologie und Salztektonik herzustellen.Eine geologische Kartierung der beiden Gebiete wurde im Sommer 1965 und 1966 durchgeführt. Sie umfaßt eine detaillierte Vermessung des Bachlaufes, der über den Nordostteil des Mønsted-Salzstockes fließt, so wie zweier Täler im Südteil des Sevel-Salzstockes.Die Ergebnisse der geologischen Untersuchung werden in Beziehung zu den geophysikalischen Daten — für Mønsted gravimetrische und magnetische gesetzt.
Résumé Cet article traite deux dômes de sel, Mønsted et Sevel, situés au Nord du Jutland, et il s'occupe en premier lieu du problème de la tectonique du sel pendant le Quaternaire, et son éventuelle influence sur la morphologie quaternaire.L'étude géologique des deux régions, faite au cours des étés 1965 et 1966, comprenait un mesurage détaillé à l'aide d'un théodolite d'une vallée qui s étend sur la partie Nord-Est du dôme de sel à Mønsted et de deux vallées dans la partie Sud du dôme de sel à Sevel. Dans le cas de Mønsted on a fait ample usage de photographies aériennes.S'appuyant sur les résultats de l'étude géologique, l'auteur propose une interprétation des données géophysiques disponibles, qui dans le cas de Mønsted, comportent des mesurages tant gravimétriques que magnétiques.
Mø nsted Sevel . . ( Mønsted).相似文献
19.
The Quaternary System is under threat of extinction as a chronostratigraphic unit in the international Geological Time Scale. In its place, the Neogene System (previously comprising Miocene and Pliocene Series), is to be extended to include the Pleistocene and Holocene Series. It may be possible to “save” the Quaternary by defining it as a Subsystem of the Neogene. In doing so, it would be an opportune time to extend the base of the Quaternary to 2.6 Ma to encompass the time during which (1) Earth's climate has been strongly influenced by bi-polar glaciation, and (2) the genus Homo first appeared and evolved. 相似文献
20.
《Quaternary Science Reviews》2005,24(14-15):1543-1546