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Available data show that the of fossil plants testified that the Antarctica was a rather warm or even hot and humid region covered with forest from Devonian to Cretaceous periods. Furthermore, even Antarctic coasts stilll kept in a warm and humid condition until early Tertiary of 37 Ma ago. It therefore can be considered that the Antarctica was not situated at its present position, but in tropic or temperate zone before the Tertiary.
Antarctic ice sheet has begun to appear in the Pligocene of 26 Ma ago. It was very much earlier than the glaciations in everywhere of the world. For the reasons a most important event was the separating of Antarctic Peninsula from South America in 35 Ma ago. Drake Passage therefore occurred and Antarctic circulation appeared, and then Antarctic continent became an isolated cold land.
Glacial changes have happened on the Antarctic ice sheet from late Tertiary to Quaternary periods. However, it has been confirmed that the Antarctic ice sheet has a great extension during the latest Pleistocene glaciation of 2500-10000a B. P. About 18000a ago, the Antarctic ice sheet was 450-1000 m thicker and much larger than that at present. By that time the ice sheet grounded on the conticental shelves. Sea level might be 100-150 m or more lower than present sea level. Sea ice covered areas in winter and in summer were 10 and 2 times respectively than that today.
It was much warmer in middle Holocene (7500-5000a B. P.) than today in Antarctic region. By that time, a large amount of ice was melt away, which, on one hand, caused a rapid rising of sea level, transgression immediately occurred; on the other hand, as continental load decreased due to the melting of ice sheet, the isostatic uplifting consequently followed and the marine terraces formed along Antarctic coasts in middle Holocene, Now the glacio-isostatic uplift is still going on. For a total uplift of 10-25 m since 6000a B. P. the mean rate of 1.5-4 mm/a is estimated in different places of Antarctic coasts.
Antarctic ice sheet (including ice shelves) has been retreating recently, Meanwhile, the inland snow accumulation has been increasing in the past decades of years, both of them are corresponding to the rising of annual mean temperature since 1910 A. D.
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On the basis of the geological mapping, isotopic choronoogcal and petrological evidences, the aumors suggested that the early Tertiary volcanic strata in the Fildes Peninsula could be divided into two formations and four members. The erupted centers in the peninsula were gradualy migrating from the western coast to the eastern and the subvolcanic intrusives were regularly distributed along a series of NWW-SEE trending faults. All of these were basically formed in two stages of volcanic activities from Paleocene to Eocene.
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This report provides a result obtained by the First Chinese Antarctic and Southern Ocean Expedition. Specimens were collected by investigators of the Second Institute of Oceanography, SOA, with plankton nets in February and March of 1985 from the South Shetland Islands, the Biscoe Islands and their vicinities, between 61°15’20S-65°30’16S, 56°18’72W-67°59’45W. Eight species belonging to 5 genera in 4 families have been identified, of which 4 species, namely
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Based on the analysis and mathematical statistics of quantitative data on both the heavy minerals and their REELa, Ce, Nd, Sm, Eu, Tb, Yb, Lu, traceZr, Hf, Th, Ta, U, Rb, Sr, Zn, Co, Ni, Cr, As, Scand majorFeelements in the surface sediments in the northwestern sea area of Antarctic Peninsula, the authors find that the heavy minerals as the carriers of REE and trace elements should not be overlooked.
Q-mode factor analysis of the heavy minerals provides a 3-factor model of the heavy mineral assemblages in the study area, which is mainly controlled by the origin of materials and sea currents. The common factor P1, composed mainly of pyroxene and metal minerals, and common factor P2, composed of hornblende, epidote and accessory minerals, represent two heavy mineral assemblages which are different from each other in both lithological characters and origin of materials. And common factor P3 probably results from mixing of two end members of the above-mentioned assemblages.R-mode group analysis, 22 elements are divided into 3 groups and 9 subgroups. These element assemblages show that they are genetically related and that they are different in geochemical behaviors during diagenesis and mineral-forming process. In addition, the relationship between the heavy mineral assemblages and the element subgroups is also discussed.
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A method of multi-spectral analysis is used to study the spectral characteristics of surface and upper-level meteorological elements over the Great Wall Station (62°12'S, 58°57'W), Antarctica and their phasecorrelation, propagation of mean oscillation at 500 hPa level in the Southern Hemisphere and their corresponding synoptic sense, the results are summed up as follows: 1. Over the sub-Antatctic zone, as in the Northern Hemisphere there generally exist quasi-weekly oscillation and quasi-biweekly oscillation. In different seasons the oscillations of meteorological elements are different: in winter season quasi-biweekly oscillation is dominant, while in summer season quasi-weekly oscillation is dominant. 2. From the Earth's surface to the lower stratosphere there is a distinct quasi-weekly oscillation at each isobaric surface, but the most intense oscillation appears at 200-300 hPa, and the oscillations of height and temperature are propagated downward. 3. Both in winter and summer seasons the quasi-biweekly oscillation are propagated from west to east, and the mean velocity of its propagation is about 7-17 longtitude/day. 4. The quasi-biweekly oscillation and the quasi-weekly oscillation over the sub -Antarctic zone are closely related to the activity and intensity variation of polar vortex at 500 hPa, while at l000 hPa they reflect an interaction between the circumpolar depression and the sub-tropical high. The quasi-biweekly oscillation may be a reflection of inherent oscillation of the polar vortex, where as the quasi-weekly oscillation is a result of forced oscillation by external disturbance.
A large number of calculations and analysis made reveals the features of medium-range oscillation over the sub-Antarctic zone. The results are of significance for understanding the behaviour of synoptic dynamics and making the weather forecast.
This work is supported by National Committee for Antarctic Research.
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It is the main task of the antarctic surveying expedition to establish the surveying system. In three times of the antarctic surveying research expeditions, a complete and accurate surveying system has been established in the Chinese Great Wall Station area. The surveying system includes geodetic coordinate system, elevation system and gravity reference system. In this paper, the surveying methods and the mathematical models for establishing these systems arc discussed, and the accuracy of results is analysed.
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During 1985-1986, 1986-1987, and 1988-1989 expeditions on Fildes Peninsula the ground temperature was measured. A total number of 218 ground temperature data were obtained. The thermal conductivity measurements were made on 121 rock samples collected during expedition. This article gives a brief analysis and summarization of these data.
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The distance from the Great Wall Station (62.2°S, 58.9°W) to Xinxiang (35.3°N, 113.8°E) is 16981 km. The path passes through the polar cap absorption region and the auroral absorption zone, and it is across the equator.
In this paper firstly the effects of short wave communication and usable time blocks and frequency ranges between the Antarctic Great Wall Station and Xinxiang from December 1985 to March 1986 are introduced. The comparison between the usable frequency ranges with the estimated MUF is made. The upper limit of frequency ranges of communication along the short great circle path basically agrees with the MUF but there is difference between them along the long great circle path.
Secondly, the result of the propagation bearings experiment in January to February 1986 is introduced in more detail, The propagation along the great circle path from the Great Wall Station to Xinxiang is the main propagation mode. But the propagation along non great circle paths occurs at times between Great Wall Station and Xinxiang. The non great circle path propagation varies with time because the ionospheric absorption and other conditions which support the non great circle path propagation are the function of the time. So the courses of the non great circle path propagation may be different in the different time. The mechanism of the constructing non great circle path propagation has been analysed. We preliminarily think the main cause of propagation along non great circle path is the ground scatter. The stronger radialization of the side lobes of the antenna and the less absorption of the ionosphere contribute to forming non great circle path propagation.
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