A NEW HISTORY OF CANTERBURY. By S. Eldred-Grigg, John Mclndoe     

PETER PERRY 《New Zealand geographer》1984,40(2):121-121

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Recent sedimentary processes in Scoresby Sund, East Greenland     

PETER MARIENFELD 《Boreas: An International Journal of Quaternary Research》1992,21(2):169-186

The fjord system of Scoresby Sund on the east coast of Greenland has been the subject of two research cruises by RV Polarstern in 1988 and 1990. Most of the year, the fjord is covered by sea-ice. Sediment input takes place mostly via drifting icebergs during the short summer period. Depending on the distance to glaciers, surface sediments carry varying proportions of coarse ice-rafted debris (IRD). The degree of sediment reworking by scouring icebergs is controlled by the depth of the fjord, with the most intense reworking in areas shallower than about 450 m depth. Both IRD contribution and intensity of sediment scouring clearly control the distribution pattern of benthic organisms.  相似文献   

Radiocarbon-dating of transitions between marine and lacustrine sediments and their relation to the development of lakes     

PETER EMIL KALAND  KNUT KRZYWINSKI  BJØRG STABELL 《Boreas: An International Journal of Quaternary Research》1984,13(2):243-258

In three different areas in western Norway, large errors are obtained in the radiocarbon dates from lacustrine sediments close to marine/lacustrine sediment boundaries. Differences occur between radiocar-bon and pollenanalytic dates and between dates at isolation/ingression contacts for lakes of the same altitude above the present sea level. Younger radiocarbon dates are also obtained below older ones in undisturbed sediments. When divergent dates occur, the radiocarbon dates always seem to be the youngest. Large differences are also found between NaOH soluble and insoluble fractions of the same sediment samples. Insoluble fractions generally yield younger dates than the soluble. Differences are not found, however, for dates younger than about 8,000 B.P. The dating errors are connected to periods with more oligotrophic conditions with isoetides. Their roots penetrate older sediments. Due to contamination of the organic part of the sediment from partly decomposed roots, some radiocarbon dates will be too young. The isoetide vegetation and the dating errors disappear when the lakes become dystrophic.  相似文献   

Deglaciation pattern and ice-dammed lakes along the Saariselkä mountain range in northeastern Finland     

PETER JOHANSSON 《Boreas: An International Journal of Quaternary Research》1988,17(4):541-552

Traces of ice-dammed lakes are found along the southern part of the Saariselkä mountain range. Various shore marks, outlet channels and fine-grained sediments are indications of open water. The shallow basins were more or less filled by dead ice. At the beginning of deglaciation the meltwaters discharged over the mountain ridge to the north. As the ice margin receded toward the southwest new outlets were opened and the meltwaters discharged to the east and southeast. The ice-dammed lakes existed and the deglaciation took place during the period 9,500-9,300 B.P. The annual rate of retreat of the ice margin averaged 130–170 m per year.  相似文献   

The Cenozoic and Late Cretaceous evolution of the Indian Ocean Basin: uncertainties in the reconstructed positions of the Indian, African and Antarctic plates   总被引：4，自引：0，他引：4  

PETER Molnar  FEDERICO Pardo-Casas  JOANN Stock 《Basin Research》1988,1(1):23-40

Abstract Reconstructions of the relative positions of the Indian, African, and Antarctic plates and their uncertainties are given for the times of selected magnetic anomalies that could be identified on adjacent pairs of these plates. Among the most certain reconstructions are those for the Antarctic and African plates, which can be determined directly from recently published magnetic anomalies from both sides of the Southwest Indian Ridge. As Patriat and his colleagues reported, there was an important change in direction and a decrease in rate of separation between Africa and Antarctica between the times of anomalies 33 and 20. India moved rapidly away from both Africa and Antarctica in the Late Cretaceous and early Tertiary periods, but slowed markedly near the time of anomaly 20 (≅ 45 Myr). The positions of the Indian plate with respect to the others are poorly constrained between the times of anomaly 5 (≅ 10 Myr) and anomaly 23 (≅ 54 Myr), but using the reconstructions of the African and Antarctic plates, the uncertainties can be reduced. Despite the relatively large uncertainties, the positions of anomalies 5, 6, and 13 on the Antarctic and Indian plates apparently cannot be described by the same parameters that describe the history of separation of Australia and Antarctica. Therefore, Stein and Okal's contention that Australia and India lie on separate plates appears to be valid not only for the present, but for the last 35 Myr.  相似文献   

Chemographic relationships of biotite and cordierite in the McGerrigle thermal aureole, Gaspé, Quebec     

J.Y. VAN BOSSE  A.E. WILLIAMS-JONES 《Journal of Metamorphic Geology》1988,6(1):65-75

Abstract Biotite and cordierite occur in a 1-km wide zone of pelitic hornfelses around the McGerrigle pluton. These phases display systematic changes in X _Fe that can be attributed to continuous reactions involving chlorite or andalusite in the system KFMASH. Through much of the zone biotite and cordierite were products of the 'breakdown'of chlorite. Close to the pluton this continuous reaction was terminated by a discontinuous reaction that introduced andalusite. Pelites which interdigitate with apophyses of the intrusive at the pluton margin contain assemblages that record a continuous reaction between biotite, cordierite, andalusite, muscovite, and quartz or, alternatively, the discontinuous breakdown of muscovite and quartz to K-feldspar and andalusite.
The mole fraction of Fe in biotite and cordierite increased significantly with the progress of the first continuous reaction and apparently decreased during the second continuous reaction. The K _D of Fe-Mg between the minerals decreased and apparently increased, respectively, during the two reactions.
Biotite-cordierite-chlorite assemblages are interpreted to have been stable at temperatures between 525° C and 615° C and biotite-cordierite-andalusite assemblages stable at temperatures between 615° C and 635° C. The confining pressure was estimated to have been < 2 kbar.
The results of this study suggest that the K _D of Fe-Mg between biotite and cordierite is a function of temperature, the Fe-Mg exchange characteristics of the controlling continuous reaction and non-ideal mixing of Fe and Mg.  相似文献   

Expanding spread profile at the northern Jan Mayen Ridge   总被引：1，自引：0，他引：1  

BÅRD JOHANSEN  OLAV ELDHOLM  MANIK TALWANI  PAUL L. STOFFA  PETER BUHL 《Polar research》1988,6(1):95-104

An expanding spread seismic profile at the central northern Jan Mayen Ridge, ESP-5, has yielded a crustal seismic velocity distribution which is similar to observations from the thinned continental crust at the Norwegian continental margin. The profile reveals a post-early Eocene sedimentary sequence, about 1. 5 km thick, overlying 1 km of volcanic extrusives and interbedded sediments. Below, there are about 3 km of pre-opening sediments above the seismic basement. The results indicate that the main ridge block is underlain by a thinned crust, possibly only 13.5 km thick. The results are compatible with a continental nature for the main ridge complex.  相似文献   

Plants and Lowland South Canterbury Landscapes     

PETER HOLLAND 《New Zealand geographer》1988,44(2):50-60

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Early mining in South Australia     

PETER J. SMITH 《Geology Today》1988,4(1):30-34

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INVESTIGATION OF COPPER(Ⅱ)-ETHYLENEDIAMINETETRAACETATE COMPLEXATION BY WINDOW FACTOR ANALYSIS OF ULTRAVIOLET SPECTRA   总被引：2，自引：0，他引：2  

EDMUND R.MALINOWSKI 《地理学报(英文版)》1993,(2)

Window factor analysis(WFA)is a self-modeling chemometric technique for obtaining the concentrationprofiles of components from evolutionary processes such as chromotography,titrations and reactionkinetics.By specifying the‘window’,i.e.the region along the evolutionary axis indigenous to acomponent,the concentration profile of the component can be obtained without recourse to anyinformation concerning the other components.Mathematical expressions required to perform suchcomputations are derived.The method is applied to the investigation of copper(Ⅱ)complexation withethylenediaminetetraacetate(EDTA)by recording and factor analyzing the ultraviolet spectra of aqueoussolutions containing a fixed amount of the disodium salt of EDTA and varying amounts of CuCl_2.Evidence for four different species of EDTA is obtained.Clues concerning the stoichiometry of thespecies are garnered from the concentration profiles.  相似文献