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71.
Barbara Wohlfarth Pavel Tarasov Ole Bennike Terri Lacourse Dmitry Subetto Peter Torssander Fedor Romanenko 《Journal of Paleolimnology》2006,35(3):543-569
Three lake sediment sequences (lakes Nero, Chashnitsy, Zaozer’e) from the Rostov-Jaroslavl’ region north of Moscow were studied
to provide information on palaeoclimatic and palaeoenvironmental changes during the past 15,000 cal yr. The multi-proxy study
(i.e., pollen, macrofossils, mineral magnetic measurements, total carbon, nitrogen and sulphur) is chronologically constrained
by AMS 14C measurements. Lake Nero provided the longest sedimentary record back to ca. 15,000 cal yr BP, while sediment accumulation
began around ca. 11,000 cal yr BP in the two other lakes, possibly due to melting of permafrost. Limnic plant macrofossil
remains suggest increased lake productivity and higher mean summer temperatures after 14,500 cal yr BP. While the late glacial
vegetation was dominated by Betula and Salix shrubs and various herbs, it appears that Betula sect. Albae became established as early as 14,000 cal yr BP. Major hydrological changes in the region led to distinctly lower lake levels,
starting 13,000 cal yr BP in Lake Nero and ca. 9000 cal yr BP in lakes Chashnitsy and Zaozer’e, which are situated at higher
elevations. These changes resulted in sedimentary hiatuses in all three lakes that lasted 3500–4500 cal yr. Mixed broad-leaved
– coniferous forests were widespread in the area between 8200 and 6100 cal yr BP and developed into dense, species-rich forests
between 6100 and 2500 cal yr BP, during what was likely the warmest interval of the studied sequences. Agricultural activity
is documented since 500 cal yr BP, but probably began earlier, since Rostov was a major capital by 862 A.D. This apparent
gap may be caused by additional sedimentary hiatuses around 2500 and 500 cal yr BP. 相似文献
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Ole Remmer 《Journal of Geodesy》1985,59(1):68-70
This note gives a new, short and non-recursive formula for Meissl’s smoothing coefficients β?. 相似文献
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The seed-like larval cases of hydroptilid caddis flies may be mistaken for plant remains in subfossil studies. However, being correctly identified, they may be important for the interpretation of former freshwater environments. Two such subfossil caddis fly remains from Holocene lake sediments and river deposits are described morphologically and their palaeoecological significance interpreted. 相似文献
79.
Ole STECHER 《Geostandards and Geoanalytical Research》1983,7(2):283-287
Fluorine in 22 international reference samples has been determined with an ion selective electrode following fusion with a Na2 bCO3 -ZnO mixture. To eliminate the effect of fluorine complexes in the solutions, the results presented are means of fluoride determinations from a standard calibration curve and from the method of standard addition. Together with these new determinations an updated compilation of USGS-I reference samples is presented. 相似文献
80.
Ole Rn Clausen Ole Bjrslev Nielsen Mads Huuse Olaf Michelsen 《Global and Planetary Change》2000,24(3-4)
The timing and effect of the Cenozoic uplift of Scandinavia has been investigated using a multi-disciplinary approach involving sedimentological, seismic and biostratigraphic data from the Danish and the adjacent Norwegian parts of the North Sea Basin. It is concluded that significant uplift took place periodically throughout the Palaeogene possibly marking an earlier onset of the so-called “Neogene uplift” of Scandinavia. This conclusion is based on a number of sedimentological observations, including smectite content, grain-size variations, kaolinite thermal stabilities and Tmax values supported by seismic reflection geometries and biostratigraphic data. These data indicate several phases of re-working of Palaeogene and older sediments situated further to the east and northeast during the middle to late Eocene and during the middle to late Oligocene. The tectonic patterns were similar during the late Paleocene and the Oligocene with some inversion taking place, whereas no inversion has been observed during the Eocene. Main provenance areas were to the north and northeast during the Paleocene and Oligocene, whereas the Eocene sediments originate mainly from the British Isles to the west. It is proposed that Palaeogene uplift of Scandinavia was associated with regional tectonic movements along crustal zones of weakness, which were reactivated as they accommodated strain induced by the Alpine Orogeny and the opening of the North Atlantic. 相似文献