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1.
The western coast of Svalbard is one of the world's most important seabird regions (Belopol'skij 1961; Løvenskiold 1964; Norderhaug et al. 1977), due to the favourable water temperatures, light regime and amounts of mineral salts (Norderhaug et al. 1977).
Seabirds have been censused several times in this area (Kristoffersen 1962; Larsen 1965; Dhondt et al.1969; Voisin 1970; Norderhaug 1974; Sendstad 1978; Alendal et al. 1982).
Except for Larsen (1965), there is no comprehensive and quantitative survey of any part of northwestern Svalbard. Further east, Jepsen & Mobæk (1983) surveyed the area between Gråhuken and Nordaustìandet.
Recent concern about the potentially detrimental effects of planned oil exploration and increased human activities in the high Arctic has emphasized the need for more information on the ecology in these regions. This paper provides more comprehensive data on seabird populations in northwestern Svalbard, between southern Prins Karls Forland and Verlegenhuken. The results supplement the studies carried out in 1978 and 1979 by Jepsen & Mobæk (1983) between Verlegenhuken and Kong Karls Land.  相似文献   

2.
Uncertainty remains if ice–free marginal areas existed on the west coast of Svalbard during the Late Weichselian. Field mapping and correlation to well dated raised beach sequences on nearby Brøggerhalvøya reveal the existence of two generations of raised beach deposits on northern Prins Karls Forland. Distinct beach ridges rise up to the inferred Late Weichselian marine limit at 18 m a.s.l. Discontinuous pre–Late Weichselian beach deposits rise from the Late Weichselian marine limit up to approximately 60 m a.s.l. Expansion of local glaciers during the Late Weichselian is indicated by the limited distribution of a till that overlies parts of the older beach sequence. Stratigraphic data and chronological control indicate deposition in a shallow marine environment before 50 ka bp . Correlation to stratigraphic sites on western Svalbard suggests deposition at c . 70 ±10 ka. Glaciotectonic structures disclose expansion of local glaciers into the For–landsundet basin during stage 4 or late stage 5 high relative sea level. Palaeotemperature estimates derived from amino acid ratios indicate that during the time interval c . 70 to 10 ka the area was exposed to cold subaerial temperatures with low rates of racemization. Pedogenesis and frost–shattered clasts at the contact between c . 70 ka deposits and Holocene deposits further indicate a prolonged period of subaerial polar desert conditions during this time interval. The evidence suggests that the Barents Sea ice sheet did not extend across northern Prins Karls Forland during the Weichselian. It is inferred that during the Late Weichselian, ice was drained throughout the major fjords on the west coast of Svalbard and that relatively large marginal areas experienced polar desert conditions and minor expansions of local glaciers.  相似文献   

3.
Svalbard reindeer were exterminated on the island of Prins Karls Forland just after the turn of the last century. In July 1994, after a period of 90 years, reindeer were again observed on the island.  相似文献   

4.
This paper presents a simple analytical model for estimating rock glacier age by coupling the ratio of frontal advance to total rock glacier length and the ratio of debris volume in the rock glacier to present debris flux in the talus cone–rock glacier transition zone. The model was applied to two rock glaciers at Prins Karls Forland, Svalbard. By assuming volumetric debris contents in the deforming layer of the rock glacier of between 0.3 and 0.4, we obtained age estimates for the rock glaciers of between 12 ka and 24 ka. The corresponding average rockwall retreat rates are between 0.30 and 0.62 mm a‐1. Considering the limitations of the model, we suggest a minimum age of 13 ka for the initiation of rock glacier development. Using this age, rockwall retreat rates for the seven rock glaciers investigated at Prins Karls Forland are between 0.13 and 0.64 m ka‐1 (assuming the volumetric debris content for the whole rock glacier/talus cone is 0.35). The model requires further testing on other datasets, better field estimates of the debris content and depth of the deforming layer, and could also benefit from the inclusion of an unsteady debris supply function in order to refine age estimates.  相似文献   

5.
This note reports the occurrence of two generations of 14C dated raised beach deposits at Pricepynten. southern Prins Karls Forland, western Svalbard, dated to < 12 Kya and >30 Kya. In addition two new 14C ages of ca. 9.2 and 1.8 Ky are presented from Myrilus eclulis and a buried peat deposit, respectively.  相似文献   

6.
Two raised marine sequences from Prins Karls Forland, western Svalbard, interpreted to have been deposited during part of isotope substage 5e (Eemian) and substage 5a, were studied for foraminifera content. Time constraints are given by 14C ages, infrared stimulated luminescence age estimates and amino acid ratios in subfossil marine molluscs. A diamicton (unit B) separates the two marine sequences and reflects an advancement of local glaciers sometime late in isotope stage 5. The two marine sequences contain diverse benthic foraminiferal faunas, indicating periods of a relatively warm and seasonally ice-free marine shelf environment. Compared to the lowermost sequence (unit A), the upper marine sequence (unit C) seems to reflect a more shallow environment that could have resulted from the global lowering of the sea level towards the end of isotope stage 5. Our results further emphasise the problem of biostratigraphic distinction between interglacial and interstadial deposits at high latitudes, with temperature conditions for substage 5a close to those of substage 5e and present conditions.  相似文献   

7.
Rock glaciers occur as lobate or tongue-shaped landforms composed of mixtures of poorly sorted, angular to blocky rock debris and ice. These landforms serve as primary sinks for ice and water storage in mountainous areas and represent transitional forms in the debris transport system, accounting for ~ 60% of all mass transport in some alpine regions. Observations of active (flowing) alpine rock glaciers indicate a common association between the debris that originates from cirque headwalls and the depositional lobes that comprise them. The delivery of this debris to the rock glacier is regulated primarily by the rate of headwall erosion and the point of origin of debris along the headwall. These factors control the relative movement of individual depositional lobes as well as the overall rate of propagation of a rock glacier. In recent geophysical studies, a number of alpine rock glaciers on Prins Karls Forland and Nordenskiöldland, Svalbard, Norway, and the San Juan Mountains of southwest Colorado, USA, have been imaged using ground penetrating radar (GPR) to determine if a relationship exists between the internal structure and surface morphology. Results indicate that the overall morphologic expression of alpine rock glaciers is related to lobate deposition during catastrophic episodes of rockfall that originated from associated cirque headwalls. Longitudinal GPR profiles from alpine rock glaciers examined in this study suggests that the difference in gross morphology between the lobate and tongue-shaped rock glaciers can be attributed primarily (but not exclusively) to cirque geometry, frequency and locations of debris discharge within the cirque, and the trend and magnitude of valley gradient in relation to cirque orientation. Collectively, these factors determine the manner in which high magnitude debris discharges, which seem to be the primary mechanism of formation, accumulate to form these rock glaciers.  相似文献   

8.
Reeve et al. (2022) address the stratigraphic record of continental breakup by focusing on a set of stratigraphic unconformities from a proximal sector of the NW Australian continental margin, inboard from the Exmouth Plateau. They suggest that such unconformities can potentially document a well-defined three-stage process: end of the syn-rift phase, formation of a wide continent-ocean transition zone (COTZ) and generation of ‘true’ Penrose-type oceanic crust. We counterargue that continental breakup is a protracted event that can only be understood via seismic- and chronostratigraphic correlations of strata, and their composing sequences, across and along rifted margins. Tying proximal stratigraphic unconformities to magnetic anomalies outboard from the study area in Reeve et al. (2022) is open to question. In parallel, we suggest that age resolutions of ca. 1 Ma are not achievable using the micropaleontological data presented in Reeve et al. (2022), with an important reworking of microfossil assemblages potentially occurring during the erosional process forming local and regional unconformities. Our discussion addresses these points in more detail.  相似文献   

9.
The geologic origin of subhorizontal reflections, often observed in crustal seismic sections, was investigated by establishing metamorphic facies and strength of rocks in depth, and correlating these properties to seismic reflection sections from eastern Hungary. Estimation of the depths of metamorphic mineral stability zones utilized the principles developed by Fyfe et al. and known geothermal data of the area. The strength versus depth profile was derived by relating local seismic P -wave interval velocities to Meissner et al. 's activation energy. The results show that the series of subhorizontal reflections, observed in the Pannonian Basin, are a consequence of combined metamorphic and rheologic changes in depths. The synthesis of the integrated data set suggests that the retrograde alteration of the pre-Tertiary basement above the percolation threshold was made possible by the softening effect of shear zones and their water-conducting capacity. The subhorizontal reflections of highest energy, of the consolidated crust below the percolation threshold, originate in the depths of greenschist, amphibolite and granulite metamorphic mineral facies, which were formed in geothermal and pressure conditions similar to those existing today. These results imply the overprint of earlier (Variscan) metamorphic sequences of the crust by more recent retrograde metamorphic processes.  相似文献   

10.
Magnetostratigraphic sampling of the Middle Triassic Badong Formation in South China was conducted at three sections. A dual-polarity characteristic remanent magnetization (ChRM) resolved from most samples by thermal demagnetization is shown to have been acquired prior to folding. The primary nature of the ChRM is corroborated by the discovery of the same magnetic polarity at equivalent stratigraphic levels in more than one section. The relative sample VGP (virtual geomagnetic pole) latitudes define nine magnetozones for the three major constituent members of the formation. Comparison with the Mid-Triassic magnetic polarity sequence observed from the western Tethyan region appears to indicate that the bulk of the Badong Formation is Anisian in age and that Ladinian sediments are largely missing. This agrees with palaeontological and stratigraphic evidence in the region and supports the view that Ladinian regression is a major event in the geological evolution of South China, which may signal the onset of amalgamation of the Yangtze Block (YB) with the North China Block (NCB).  相似文献   

11.
萨拉乌苏动物群   总被引:13,自引:2,他引:13  
谢骏义  高尚玉 《中国沙漠》1995,15(4):313-322
目前在萨拉乌苏地区共发现脊椎动物化石46种,其中哺乳类34种,鸟类12种。本文根据新采集到的80多件化石的出产层位和对前人资料的分析,把全部化石按地层即萨拉乌苏组、城川组和大沟湾组作了统计。并根据地层划分和化石种类的变化,新建立了城川动物群。萨拉乌苏动物群和城川动物群在时代上分别属于晚更新世中期和晚更新世中期之末到晚更新世晚期,代表较暖湿和干冷的气候环境。  相似文献   

12.
Glacial striae and other ice movement indicators such as roche moutonées, glacial erratics, till fabric and glaciotectonic deformation have been used to reconstruct the Late Weichselian ice movements in the region of eastern Svalbard and the northern Barents Sea. The ice movement pattern may be divided into three main phases: (1) a maximum phase when ice flowed out of a centre east or southeast of Kong Karls Land. At this time the southern part of Spitsbergen was overrun by glacial ice from the Barents Sea; (2) the phase of deglaciation of the Barents Sea Ice Sheet, when an ice cap was centred between Kong Karls Land and Nordaustlandet. At the same time ice flowed southwards along Storfjorden; and (3) the last phase of the Late Weichselian glaciation in eastern Svalbard is represented by local ice caps on Spitsbergen, Nordaustlandet, Barentsoya and Edgeøya.
The reconstructed ice flow pattern during maximum glaciation is compatible with a centre of uplift in the northern Barents Sea as shown by isobase reconstructions and suggested by isostatic modelling.  相似文献   

13.
The late Palaeozoic to Triassic sedimentary record of the central Argentinean offshore was analysed through the integration of data from exploratory wells and 2D seismic lines. Our interpretations were combined with existing ones in Argentina, Uruguay, Brazil and South Africa for their analysis in the late Palaeozoic south‐western Gondwana context. The mapped upper Palaeozoic‐Lower Triassic stratigraphic record offshore Argentina bears a thickness of +7000 m south of the Colorado basin and encompasses the time span between Pennsylvanian and Lower Triassic; this means that it triples that of the Sierras de la Ventana of Argentina and involves a far larger time span. On the basis of seismic stratigraphic interpretations in localities near the coast, we interpret that a strong denudation process removed a great portion of the stratigraphic record in the Sierras de la Ventana, the surrounding plains and the Tandilia system of Buenos Aires. The seismic stratigraphic configuration of the late Palaeozoic succession shows continuous and parallel reflections in a wide sediment wedge extending for more than 1000 km between the Gondwanides orogen core to the south and offshore Uruguay to the north. Two salient aspects of this sedimentary wedge are that no flexural depocentre was observed at the Ventania fold belt front, and that deformation in the orogenic front is post‐Lower Triassic. The original westwards extent of the basin is interpreted to have encompassed the whole of Buenos Aires province in continuity with the Chacoparaná basin; to the east continuity and a straightforward correlation with the Karoo basin was interpreted. The name of Hespérides Basin is proposed herein to refer to a Pennsylvanian to Lower Triassic basin mainly controlled by dynamic subsidence that encompasses and exceeds the area of the Sauce Grande and Colorado basins and the Claromecó fore‐deep in Argentina. The Hespérides basin is interpreted to have been in lateral continuity with the Kalahari, Karoo and Chacoparaná basins of Africa and South America forming a +3 000 000 sq. km depocentre.  相似文献   

14.
Einunna kvartærgeologisk kart i målestokk 1:50000 (Sollid &; Sørbel 1979a) er et av flere kvartærgeologiske kart fra Dovrefjell og tilgrensende områder, som er utarbeidet ved Geografisk institutt, Universitetet i Oslo. Av andre kart i samme målestokk foreligger kartbladet Folldal med tilhørende beskrivelse (Sollid &; Carlson 1979, 1980), mens kartbladet Hjerkinn er klart til trykking (Sollid &; Sørbel, in prep.). I områdene Øst og nord for kartbladet Einunna er det laget to kvartærgeologiske kart i målestokk 1:100000 (Sollid et al. 1978, Sollid et al. 1980a &; b)  相似文献   

15.
The Nepean River terraces are a sequence of Tertiary and Quaternary alluvial deposits to the west of Sydney, NSW. In the last 85 years over 20 soil and geological maps covering the area have been produced. Errors and interpretations introduced in early regional scale maps were perpetuated for over 40 years despite numerous new editions. Regional scale geological maps in the 1950s and 1960s failed to take account of good detailed work by geographers, soil surveyors and geology students. Detailed geological and soil stratigraphic mapping in the past 10 years drew attention to these problems and has highlighted the important contributions made by the earlier detailed studies. New interpretations can now be tested against a substantial body of data. Contemporary regional soil and geological maps have taken account of these detailed studies and so present a more consistent approach than in the past.  相似文献   

16.
本文通过“豫灵人”发现区的地质构造、黄河演进、地层层序、地貌形态以及古生物等方面的分析与研究,提出了本区第四纪古地理环境演变与“豫灵人”出现之间有着紧密相关关系的一些看法和认识。  相似文献   

17.
Prokopenko and Kendall (J Paleolimnol doi:, 2008) criticise the work presented in Fedotov et al. (J Paleolimnol 39:335–348, 2008), and instead propose an alternative interpretation for the grain-size evolution recorded in the KDP-01 core, retrieved from the central part of Lake Khubsugul. Their interpretation is based (i) on a seismic-stratigraphic re-interpretation of sparker seismic profile khub012 (which they copied from Fedotov et al. (EOS Trans 87:246–250, 2006)), (ii) on the presupposition that changes in lake level are the dominant control on facies distribution in Lake Khubsugul, and (iii) on the invalidation of our age-depth model. In this reply to their comment, we demonstrate that they interpreted seismic artefacts and geometries caused by changes in profile orientation as true stratigraphic features and that the lake-level reconstruction they derive from this interpretation is therefore incorrect. We also demonstrate that their grain-size predictions, which they consider to be predominantly driven by changes in lake level, are inconsistent with the measured sulphate concentration, which is a demonstrated proxy of lake level in Lake Khubsugul, and with the measured grain-size record. Finally, we point out that even if there would be a problem with the age-depth model, this problem would not affect the part of the sedimentary sequence discussed in Fedotov et al. (J Paleolimnol 39:335–348, 2008).  相似文献   

18.
Candidates for possible Precambrian proto-basement throughout Svalbard are considered and evaluated. The paper provides a tectono-stratigraphic framework for consideration of new data. Proto-basement, in the sense of basement in Proterozoic time, implies the occurrence of a Precambrian tectonic event. Vendian rocks are widespread in Svalbard and, because there is no known Vendian major tectonic event, the search is narrowed to pre-Vendian rocks. The approach is primarily tectono-stratigraphic, to identify a significant break by unconformity, contrast in metamorphic facies and isotopic age determinations.
The paper concludes that the following rock units are proto-basement: Isbjømhamna and (newly defined) Eimfjellet groups, Nordbukta Group, Magnethøgda Group, the Richarddalen Complex; the Atomfjella Complex, the Brennevinsfjorden Group and the granitoids related to the Kapp Hansteen Group and the Duvefjorden Complex. While considered unlikely to be proto-basement the following cannot be ruled out: the Mefonntoppane and Kistefjellet rocks and the Sigfredbogen unit, the blue-schist Vestgötabreen rocks, the Pinkie Formation and parts of the Kongsvegen Group.
Terrane implications are consistent with the three terrane model of Harland & Wright (1979), modified by Harland et al. (1993); but the data presented here hardly constrain such a model. In so far as the conclusions here are valid the effect is to subtract from, rather than add to, the outcrops commonly mapped as likely proto-basement.  相似文献   

19.
Palaeo- and archaeointensity determinations of the geomagnetic field are limited by mineralogical alteration that may occur when samples are heated in the laboratory to produce a TRM ( Thellier & Thellier 1959 ; Shaw 1974 ). By using microwave excitation of the magnetic grains we have been able to create a TRM without significantly heating the bulk samples, thereby avoiding thermal alteration ( Walton et al . 1993 ; Shaw et al . 1996 ). When applied to Peruvian ceramics in a manner analogous to the standard Thellier method, the microwave technique was found to reduce the scatter dramatically in the archaeointensity results ( Shaw et al . 1996 ). In the present study we apply this microwave technique to a collection of Chinese ceramics covering the time interval 2700–7500  yr BP. These ceramics have already been investigated using adaptations of both Thellier's ( Coe 1967 ) and Shaw's ( Rolph & Shaw 1985 ) palaeointensity methods ( Yang et al . 1993a ). Although an acceptable agreement was found between those two methods, the equivalent virtual axial dipole moments (VADMs) were significantly lower than for the global model of McElhinny & Senanayake (1982 ). The present study, using the microwave technique with cooling-rate correction, has provided more consistent VADMs, and is much closer to the global model.  相似文献   

20.
A new Lower Cretceous lithostratigraphic unit of the Western Barents Shelf, named the Klippfisk Formation, is formally introduced. The formation represents a condensed carbonate succession deposited on platform areas and structural highs, where it consists of limestones and marls, often glauconitic. The limestones may have a nodular appearance, and fossil debris, which are dominated by Inoceramus prisms, may be abundant. The Klippfisk Formation is composed of two members: the Kutling Member defined herein from cores drilled on the Bjarmeland Platform, and the coeval Tordenskjoldberget Member described on Kong Karls Land. The base of the formation is defined by the abrupt decrease in gamma-ray intensity, where the dark shales of the underlying Hekkingen or Agardhfjellet formations are replaced by marls. It is often unconformable. The Klippfisk Formation is of Berriasian to Early Barremian age and appears to be time-transgressive over parts of the Western Barents Shelf (including Kong Karls Land). It passes laterally into the basinal Knurr Formation. On Kongsøya (Kong Karls Land) a thin shale unit, bounded by unconformities, earlier included in the Tordenskjoldberget Member, represents the northernmost extension of the overlying Kolje Formation in the Barents Shelf.  相似文献   

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