广西海洋资源概况及开发刍议

广西海洋资源丰富 ,品种繁多 ,为了更好开发 ,建议从法制、宣传教育、普及海洋资源有关知识 ,提高人们整体素质做起 ,进一步抓住机遇 ,合理开发 ,才能取得良好效益 ,达到预定目标     

Zircon U–Pb age, trace element and Hf isotope composition of Kongling terrane in the Yangtze Craton: refining the timing of Palaeoproterozoic high-grade metamorphism

U–Pb age, trace element and Hf isotope compositions of zircon were analysed for a metasedimentary rock and two amphibolites from the Kongling terrane in the northern part of the Yangtze Craton. The zircon shows distinct morphological and chemical characteristics. Most zircon in an amphibolite shows oscillatory zoning, high Th/U and ¹⁷⁶Lu/¹⁷⁷Hf ratios, high formation temperature, high trace element contents, clear negative Eu anomaly, as well as HREE-enriched patterns, suggesting that it is igneous. The zircon yields a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 2857 ± 8 Ma, representing the age of the magmatic protolith. The zircon in the other two samples is metamorphic. It has low Th/U ratios, low trace element concentrations, variable HREE contents (33.8 ≥ Lu_N≥2213; 14.7 ≤ Lu_N/Sm_N ≤ 354) and ¹⁷⁶Lu/¹⁷⁷Hf ratios (0.000030–0.001168). The data indicate that the zircon formed in the presence of garnet and under upper amphibolite facies conditions. The metamorphic zircon yields a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 2010 ± 13 Ma. These results combined with previously obtained Palaeoproterozoic metamorphic ages suggest a c. 2.0 Ga Palaeoproterozoic collisional event in the Yangtze Craton, which may result from the assembly of the supercontinent Columbia. The zircon in two samples yields weighted mean two-stage Hf model ( T _DM2) ages of 3217 ± 110 and 2943 ± 50 Ma, respectively, indicating that their protoliths were mainly derived from Archean crust.     

Isotopic evidence for holocene climatic changes in Bosten Lake, Southern Xinjiang, China

Based on the δ¹³C and δ¹⁸O fluctuation of lacustrine carbonate, CaCO₃ content and sporo-pollen data, a palaeoclimatic history of Bosten Lake during the Holocene has been outlined, several stages of climatic changes are divided, and the following result es are obtained: (1) Palaeoclimatic changes revealed by carbonate isotope around Bosten Lake are basically identical with that revealed by other geological records in Xinjiang. Environmental changes presented apparent Westlies Style model: during cold period, relative humidity increased, δ¹⁸O, δ¹³C and CaCO₃ appeared low; but in warm periods, the dry regime aggravated. (2) The temperature reflected by δ¹⁸O exist evident features being increase in the late period during the Holocene. Together with the δ¹³C, pollen and CaCO₃ analyses, several cold and warm phases which are of broad regional significance can be identified. The warm peaks occurred at about 11.0 ka B.P., 9.4 ka B.P., 7.5 ka B.P., 5.0 ka B.P., 3.0 ka B.P. and 2.0 ka B.P.; the cold peaks at 11.5 ka B.P., 10.5 ka B.P., 8.8 ka B.P., 5.5 ka B.P., 3.3 ka B.P., 2.2 ka B.P. and 1.5 ka B.P.. (3) Several climatic events with the nature of “abrupt climatic changes” are revealed in the periods of 11.0 ka B.P. −10.5 ka B.P., 9.4 ka B.P. −8.8 ka B.P., 5.5 ka B.P. −5.0 ka B.P. and 2.0 ka B.P. −1.5 ka B.P.. (4) The results show that carbonate isotopic record of lacustrine sediment in arid area is very sensitive to climatic changes, and may be play a very important role in understanding the features and mechanism of palaeoclimatic changes.     

Tephrochronology and tephrostratigraphy of two Pleistocene continental fossiliferous successions from central Italy

The stratigraphical context of two Middle Pleistocene fossiliferous palaeosols from Central Italy (Abruzzo and Tuscany) have been studied. Small mammals and molluscs occur in both palaeosols, which are covered by tephra layers that were analysed using an interdisciplinary approach. Application of fission‐track dating to apatites separated from the Case Picconetto tephra (Pescara, Abruzzo), yielded an age of 0.48 ± 0.04 Ma, indistinguishable from those previously determined for the Campani Quarry (Lower Valdarno, Tuscany) (0.46 ± 0.05 Ma and 0.48 ± 0.05 Ma). Geochemical and petrographic investigations indicate that these tephra originated from different volcanoes, the Alban Hills Volcanic Complex and the Vico Volcano (Latium) respectively. Small mammal and mollusc assemblages indicate different palaeoclimatic and palaeoenvironmental conditions for the Case Picconetto and Campani Quarry palaeosols. Warm and humid conditions can be inferred for the Campani Quarry site, whereas open and cold conditions can be inferred for Case Picconetto. On the basis of faunal data, fission‐track dates and attribution of tephra to specific volcanic eruptions, we suggest a correlation of these faunas with marine oxygen isotope stage 14 (Case Picconetto) and with marine oxygen isotope stage 11 (Campani Quarry), respectively. Copyright © 2003 John Wiley & Sons, Ltd.     

Optical monitoring of the quasar 4C 38.41

The results of a photometric monitoring of the quasar 4C 38.41, performed at the optical R and B bands in 2002 February–March, are presented. With a 60/90 cm Schmidt telescope at the Xinglong station of the National Astronomical Observatories of China, we observed the source exhibiting amplitude variations of up to 0.78 mag in both bands during the whole campaign. Intraday and even intranight variations are detected as well. A typical variability time-scale of about 36 d is derived from our 2-month observations at the optical bands, which is identical to that found at a radio wavelength of 92 cm, suggesting a common origin for the variations in 4C 38.41 from optical to radio bands.     

Mezen Bay—a key area for understanding Weichselian glaciations in northern Russia

Sediment successions in coastal cliffs around Mezen Bay, southeastern White Sea, record an unusually detailed history of former glaciations, interstadial marine and fluvial events from the Weichselian. A regional glaciation model for the Weichselian is based on new data from the Mezen Bay area and previously published data from adjacent areas. Following the Mikulinian (Eemian) interglacial a shelf‐centred glaciation in the Kara Sea is reflected in proglacial conditions at 100–90 ka. A local ice‐cap over the Timan ridge existed between 75 and 65 ka. Renewed glaciation in the Kara Sea spread southwestwards around 60 ka only, interrupted by a marine inundation, before it advanced to its maximum position at about 55–50 ka. After a prolonged ice‐free period, the Scandinavian ice‐sheet invaded the area from the west and terminated east of Mezen Bay about 17 ka. The previously published evidence of a large ice‐dammed lake in the central Arkhangelsk region, Lake Komi, finds no support in this study. Copyright © 2003 John Wiley & Sons, Ltd.     

Coma Morphology of Three Non-periodic Comets

The coma morphology and short-term evolution was investigated of three non-periodic comets in retrograde orbits, C/2001 Q4 (NEAT), C/2002 T7 (LINEAR), and C/2003 K4 (LINEAR). All three comets display distinct coma features, which were very different from one comet to the next and remained rather constant in shape during the observational period. A single, broad feature perpendicular to the sun-tail direction dominated the coma of C/2003 K4 in all used filters (B,V,R,I), whereas the coma of Comet C/2002 T7 exhibited different features in blue and red filters. C/2001 Q4 showed rather complex coma morphology with clear short-term variability in coma brightness. Therefore, these non-periodic comets neither show a featureless coma nor any similarities of the features detected. The overall distribution of coma material was investigated from the shape of radial coma profiles averaged around the comet nucleus. For C/2001 Q4 and C/2002 T7, the slopes fitted to the linear part of these profiles are flatter in the blue than in the red, which can be explained by the presence of coma gas. For C/2003 K4 no such difference is indicated in the May observations (r = 2.3 AU), while in July (r = 1.7 AU) the profiles in the B-filter are flatter than in V, R, and I, hence gas contamination was relevant at least in the B filter. The R and I filter images were used to determine approximate Afρ values of each comet as a function of time.     

The intracluster iron distribution around 4C+55.16

We report on the metal distribution in the intracluster medium around the radio galaxy 4C+55.16     observed with the Chandra X-ray Observatory . The radial metallicity profile shows a dramatic change at 10 arcsec (∼50 kpc) in radius from half solar to twice solar at inner radii. Also found was a plume-like feature located at ∼3 arcsec to the south-west of the centre of the galaxy, which is mostly accounted for by a strong enhancement of iron L emission. The X-ray spectrum of the plume is characterized by the metal abundance pattern of Type Ia supernovae (SNeIa), i.e. large ratios of Fe to α elements, with the iron metallicity being unusually high at     solar (90 per cent error). How the plume has been formed is not entirely clear. The inhomogeneous iron distribution suggested in this cluster provides important clues to understanding the metal enrichment process of the cluster medium.     

Results from the Whole Earth Telescope — Indian contributions

The Indian team at ISRO has been part of the Whole Earth Telescope (WET) team since 1988 when we first participated in the campaign on V471 Tau. We have been part of many other observing campaigns over the last decade. This presentation traces the circumstances leading to our joining the WET team and how useful the coverage from the Indian longitude has been. The results of several pulsators from the WET runs during which we participated are also described. These include PG1159-035 the prototype of the GW Vir type of stars, RE J 0751+14 a cataclysmic variable, PG 1336-018 a binary with an sdB pulsator and finally HR 1217 a roAp star. The paper concludes with what the limitations are in our observations and how we can overcome them in the future.     

论现代航海技术与高等航海教育

针对航海技术的现状和发展趋势 ,提出了高等航海教育应向国际化、高素质化、现代化、技能化、规范化发展 ,以培养高素质的国际航运人才。