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1.
Zhang Hucai 《中国地理科学(英文版)》1997,8(4):377-382
Chronology establishment and dating data analyses on lacustrine deposits in northeastern Sahara show that vast fresh lakes
existed over there between 9900–2400 a B. P. Especially, great continuous lakes developed and got their maximum extent during
the period from 9800 a B. P. to 6450 a B. P. From 6000 a B. P. to 3600 a B. P., the evolution of the lakes experienced a new
stage with a property of drastic fluctuations and a periodicity of 600 years, which was the response to the climatic environment
changes. On the aspect of the relation between natural environment and the human, the warm-humid period in the Holocene was
not only a very important time for human development and evolution, but also was a moment for human reproduction and division.
On the other hand, this warm-humid period was also a distinguished time to natural environment changes, the accumulation of
the strong weathered debris and fine materials formed the basements for the formation of the Sahara Desert.
Supported by the National Natural Science Foundation of China, German Research Foundation and Gansu Provincial Natural Science
Foundation. 相似文献
2.
１ ＳＴＵＤＩＥＤＲＥＧＩＯＮＡＮＤＡＮＡＬＹＳＩＳＭＥＴＨＯＤＬｏｃａｔｅｄａｔｎｏｒｔｈｗｅｓｔｅｒｎｍａｒｇｉｎｏｆＴｅｎｇｇｅｒＤｅｓｅｒｔａｎｄ７０ｋｍｎｏｒｔｈｅａｓｔｏｆＭｉｎｑｉｎＣｏｕｎｔｙｉｎＧａｎｓｕＰｒｏｖｉｎｃｅ，ＱｉｎｇｔｕＬａｋｅｂｅｌｏｎｇｓｔｏｔｈｅＳｈｉｙａｎｇＲｉｖｅｒＤｒｙＤｅｌｔａ，ａｎｄｔｈｅａｌｔｉｔｕｄｅｉｓ１２９２－１３１０ｍ．Ｔｈｅｒｅｇｉｏｎｈａｓｔｈｅｃｈａｒａｃｔｅｒｏｆｔｅｍｐｅｒａｔｅｃｏｎｔｉｎｅｎｔａｌａｒｉｄｄｅｓｅｒｔｃｌｉ… 相似文献
3.
THE RELATIONSHIP BETWEEN INLAND LAKES EVOLUTION AND CLIMATIC FLUCTUATION IN ARID ZONE 总被引：2，自引：0，他引：2
The evolution of the inland lakes in arid and semi-arid zones is accorded with the climatic fluctuation. The humid climate is in harmony with the higher water level and greater lake water quantity budget while arid climate is in correspondence with the lower water level and little water budget. Based on the analysis of the lake fluctuation and lake budget change, with the aid of the data of geom'orphology, palynology, sedimentology and chronology, It is found that the climate experienced a warm and humid period during 7000-3500 yr. B. P. and showed a drying and warming trend in the last century in the Central Asia. 相似文献
4.
PALYNOLOGICAL RECORD OF PALEOVEGETATIONCHANGE DURING HOLOCENE AT NORTH TUMDPLAIN IN INNER MONGOLIA,CHINA 总被引：3，自引：0，他引：3
I~are~orsruDVThemiddleinnerMongoliaissituatedintherearpartoftheeasternAsianmonsonzone,itissensitivetotheclimatechange,thereforeitsenvironmentchangeintheHOIOcenehasbeenPaidattentiontobythescholarsofpaleoclimateandpal~nvirorunent.Wedidhighr~lutionPOllenanalysisonapeatprofileinpluvialfan,whichwaslocated3kmtothenorthOfQaSq,theheadquarteroftheTumdBanner,InnerMongolia,withaltitudeof1000malerssealevel.Theaverageannualtemperaturewas5.6t,annualprecipitation300--450rum,theclimatewascontinentaland… 相似文献
5.
Ecological end palaeoecological studies were carried out in a series of lakes in the Vestfold Hills (68°38＇S, 78°06＇E) on eastern Antarctic continent. Dynamics types of the lakes in environmental geomorphology and physic-chemistry, as well as features of biological community structures in different lakes were analyzed. Marine macro- and micro-fossils collected from the terraces and beaches surrounding these lakes and determined in 14C radiocarbon ages to be the Late Pleistocene, were used as evidences tc show the evolutionary processes of the lakes after sea level changes and transgressions since 18000 a B.P.. Basic modals of evolution for the lakes given in the paper could be regarded as not only explaining the history of environmental and ecological changes in VH lakes, and also reflecting of local environmental evolution in Antarctic region and global climate changes from past to present time. 相似文献
6.
The Qaidam Basin is. a tectonically controlled depression at 2700 m altitude on the northern margin of the Tibet Plateau. A succession of Neogene clastic sediments indicates lake depocentre migration from NW to SE. Towards late Pliocene, evaporative conditions developed with formation of gypsum, halite, celestite, mirabilite and bloedite. Continued deformation through Pleistocene developed a series of NW- SE trending domes and troughs. This setting continued to exert a controlling influence on basin and brine evolution and the progressive development of sulfate to chloride brines as, dry conditions intensified in late Pleistocene, at the end of which, extensive flat floors were formed in Dalangtan, Qarhan and other playas.The, model, which was set up based on the synthetic analyses, divides the fluctuating palaeoclimate since 750ka,B. P. into 11 warm and humid stages and 10 dry and cold stages. The water of the lakes evaporated during the dry-cold periods and were freshened during the warm-humid periods 相似文献
7.
This paper describes the paleoclimatic changesoccurring in the Chaiwopu Basin since 730,000 yr.B.P., together with theformation and evolution of Chaiwopu Lake based on the chronology and characteristics of a core drilled in the basin. Analysis of the drilling core provides information on the climate and environment of the area. It would appear that the paleoclimatic changes that occurred in the basin during the Pleistocene was controlled by the relationship between the sun and the earth and by Long-term (10,000 yr.) climatic cycles. The climate tended to cold-dry during the glacial period (ice age) and warm-moist during the interglacial. Following the warm period of the Holocene, short-term (1,000 yr.) climatic cycles occurred in cool-moist periods, similar to the "Little Ice Age", alternated with warm-dry periods. 相似文献
8.
Traditionally, the mid-Holocene in most parts of China was thought to be warmer with higher precipitation, resulting from a strong Asian summer monsoon. However, some recent researches have proposed a mid-Holocene drought interval of millennial-scale in East Asian monsoon margin areas. Thus whether mid-Holocene was dry or humid remains an open issue. Here, Zhuyeze palaeolake, the terminal lake of the Shiyang River Drainage lying in Asian monsoon marginal areas, was selected for reconstructing the details of climate variations during the Holocene, especially mid-Holocene, on the basis of a sedimentological analysis. Qingtu Lake (QTL) section of 6.92m depth was taken from Zhuyeze palaeolake. Multi-proxy analysis of QTL section, including grain size, carbonate, TOC, C/N and δ13C of organic matter, was used to document regional climatic changes during 9-3 cal ka B.P. The record shows a major environmental change at 9.0-7.8 cal ka B.P., attributed to a climate trend towards warmth and humidity. This event was followed by a typical regional drought event which occurred during 7.8-7.5 cal ka B.P. And a warm and humid climate prevailed from 7.5 to 5.0 cal ka B.P., attributed to the warm/humid Holocene Optimum in this region. After that, the climate gradually became drier. Moreover, comparison of the climate record from this paper with the summer insolation at 30°N indicates that the climate pattern reflecting the Asian monsoon changes was caused by insolation change. 相似文献
9.
This paper describes the paleoclimatic changesoccurring in the Chaiwopu Basin since 730,000 yr.B.P., together with theformation
and evolution of Chaiwopu Lake based on the chronology and characteristics of a core drilled in the basin. Analysis of the
drilling core provides information on the climate and environment of the area. It would appear that the paleoclimatic changes
that occurred in the basin during the Pleistocene was controlled by the relationship between the sun and the earth and by
Long-term (10,000 yr.) climatic cycles. The climate tended to cold-dry during the glacial period (ice age) and warm-moist
during the interglacial. Following the warm period of the Holocene, short-term (1,000 yr.) climatic cycles occurred in cool-moist
periods, similar to the “Little Ice Age”, alternated with warm-dry periods. 相似文献
10.
The environmental changes during the Late Pleistocene were more obvious in the eastern China than in other areas at the same latitude, which either between northern and southern, or between land and sea of the eastern China were mostly non-synchronous. The transitional period prior to the last glaciation came about in the northern part of the eastern China about 115,000 yr. ago. The desert environments of the inland of the north China were developed both in the glacial maximum and in the warm interglacial period, but the loess accumulation mostly took place during the glacial period. The sand dunes and the periglacial solifluctions in the lower Changjiang (Yangtze) River region were formed during the last glacial period. The event of lowest surface temperature occurred at 98,000 yr. B.P. and 59,000 yr. B.P. in the northern part of the South China Sea but not during the full-glacial stage. The phenomena mentioned . above were the result of the following reasons that the paleo-environmental changes in the 相似文献
11.
1 ＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＷＡＴＥＲＴＲＡＮＳ ＦＯＲＭＡＴＩＯＮＩＮＡＲＩＤＬＡＮＤＴｈｅｒｅｇｕｌａｒｉｔｉｅｓｏｆｗａｔｅｒｔｒａｎｓｆｏｒｍａｔｉｏｎｉｎｓｔｒｅａｍｆｏｒｍｉｎｇａｒｅａｓａｎｄｓｔｒｅａｍｄｉｓａｐｐｅａｒｉｎｇａｒｅａｓａｒｅｖｅｒｙｄｉｆｆｅｒｅｎｔ.Ｉｎｓｔｒｅａｍｆｏｒｍｉｎｇａｒｅａｓ ,ｗａｔｅｒｔｒａｎｓｆｏｒｍａｔｉｏｎｉｓｍａｉｎｌｙｆｒｏｍ ｐｒｅｃｉｐｉｔａｔｉｏｎ ,ｓｎｏｗｍｅｌｔａｎｄｉｃｅｍｅｌｔｗａｔｅｒｔｏｓｕｒｆａｃｅｗａｔｅｒ… 相似文献
12.
Sporo-pollen Assemblage and Paleoclimate Events in Shelf Area of the Southern Yellow Sea Since 1.5 ka B.P. 总被引：1，自引：0，他引：1
Based on the authors‘ 1986 to 1994 sporo-pollen assemblage analysis in the southern Yellow Sea area, data from 3 main cores were studied in combination with ^14C, palaeomagnetic and thermoluminescence data. The evolution of the paleoclimate environments in the southern Yellow Sea since 15ka B.P. was revealed that, in deglaciation of the last glacial period, the climate of late glaciation transformed into that of postglaciation, accompanied by a series of violent climate fluctuations. These evolution events happened in a global climate background and related to the geographic changes in eastern China. We distinguished three short-term cooling events and two warming events. Among them, the sporo-pollen assemblage of subzone A1 showed some cold climate features indicating that a cooling event occurred at about 15 - 14ka. B .P. in early deglaciation. This subzone corresponds to the Oldest Dryas. In subzone A3 , many drought-enduring herbal pollens and some few pollens of cold-resistant Picea, Abies, etc. were found, which indicated that a cooling event, with cold and arid climate, occurred at about 12- 11ka. B.P. in late deglaciation. This subzone corresponds to the Younger Dryas. The sporo-pollen assemblage of zone B showed warm and arid climate features in postglaciation. Although the assemblage of subzone B2 indicated a cold and arid climate environment, the development of flora in subzone B2 climate was less cold than that in A3 . Subzone B2 indicated a cooling event which occurred at about 9ka B.P. in early Holocene. Subzone A2, with some distinct differences from subzone A1 and A3 , indicated a warming event which occurred at 14 - 13ka. B.P. and should correspond to a warming fluctuation. The sporo-pollen assemblage of zone C showed features of warm-moist flora and climate, and indicated a warming event which universally occurred along the coast of eastern China at 8 - 3ka B.P. in middle Holocene, and its duration was longer than that of any climate events mentioned above. This period was climatic optimum and belonged to an altithermal period in postglaciation. 相似文献
13.
Relevant geological, geographical, archaeological data were collected to study the characteristics of middle Holocene warm period and sea level high on North China coast. Middle Holocene climate and sea level change on North China coast were correlated to warm marine environment events in about 8-3 ka B.E The sea level in about 8 ka B.E was higher than present mean sea level, then fluctuated for 5 000 years and after that it became even in 3 ka B.E The highest sea level occurred in about 6-5 ka B.E; the maximum was about 2-3 m and minimum was about 1-2 m. 相似文献
14.
Analysis of 13 spore-pollen assemblage zones reflecting environmental changes since the later middle Pleistocene showed the
seccession of paleovegetation and the paleogeographic changes in the Bohai Basin and circumjacent area. Paleoclimatic variations
here can obviously be divided into 5 cold and 5 warm periods: 2 cold and 1 warm periods in 200,000–100,000 a B.P.(late middle
Pleistocene) 3 cold and 3 warm periods in 100,000–12,000 a B.P.(late Pleistocene), and 1 warm period since 12,000 a B.P. Late
Pleistocene climate tended to become colder and colder. The coldest period was in the later stage of late Pleistocene, when
the study area was a periglacial zone. The mean annual temperature then was about 10°C lower than it is now. In the middle
stage of late Pleistocene, climate became warm; the mean annual temperature then was about 3–4°C higher than it is now.
By applying principles of climatic stratigraphy, the authors deduced through sporo-pollen analysis, that the boundary between
middle and late Pleistocene should be at 178–181 m, and that between Pleistocene and Holocene should be at 12.8 m. The results
of climatic stratigraphy are consistent with those of magnetic stratigraphy.
This paper was published in Chinese inOceanologica et Limnologia Sinica.18 (3): 253–266, 1987. 相似文献
15.
According to loess and palaeosol climatic record, field observation, analysis data and14C dating, we discuss the climatic changes and the water level fluctuations of Qinghai Lake. It is pointed out that there were
four relatively warm and moist stages in Qinghai Lake basin during the Holocene. They formed in the periods from 10,300 yr.B.P.
to 8,500 yr.B.P., 7,000 yr.B.P. to 3,500 yr.B.P., 2,800 yr.B.P. to 2,000 yr.B.P. and from 1,300 yr.B.P. up to now. the climate
in the Holocene optimum period, from 7,000 yr.B.P. to 3,500 yr.B.P., was much warmer and moister than that today. Polypodium
plant grew luxuriantly around Qinghai Lake. The annual temperature was 2.5°C higher than that today, but there was no forest
at Qinghai Lake shore. It is found that there was a good relationship between precipitation and water level fluctuation. In
warm and moist period water level was high and in the cold and dry period it was low in the Holocene. There were four high
water level periods for Qinghai Lake in the Holocene, but the highest level was less than 30m above present water level.
This research is supported by Youth Foundation of Natural Science Foundation of China (No. 49101015). 相似文献
16.
刘钧枢 《地球科学与环境学报》1994,(4)
根据对Z_(37-2)孔的孢粉分析结果表明,郑州地区,自全新世以来,气候经历三次较大的波动,先是气候开始转暖,气温不高,温凉半湿润;二是气候继续升高,达到“最适宜”气候期,温暖湿润;最后是气候再度下降,降水减少,温凉偏干.本区气侯变化规律,与北京地区基本符合.依据气侯地层学的观点,并结合放射性碳年代测定,本区的全新世地层可以划分为三期:即全新世早期(距今11000～7500a),全新世中期(距今7500～2500a),全新世晚期(距今2500a至今). 相似文献
17.
18.
The characteristics of water balance in arid regions is that the streams are formed in mountain area and continuously evaporates
and infiltrates in the process of flowing to plain area, streams finally disappear in the desert or flow into the lakes, which
are the low reaches of the rivers. But the distribution and transformation of water in Xinjiang, China have changed under
the influences of human activities. The influences of human activities take place in a short time and regionally, especially
in arid land where water is the key factor of environment. Water inside of oasis has increased, and water out of oasis or
at the lower reaches of the river has decreased. Human activities have caused the environment changes in both positive and
negative aspects by changing the circulation and distribution of water. Under the influence of human activities, oases in
Xinjiang have expanded, meanwhile some lakes have contracted desertification is serious, natural vegetation has declined and
natural environment out of oasis has degenrated.
Foundation item: Under the auspices of the National Natural Science Foundation of China(49771009).
Biography: LI Xin(1940 -), male, a native of Anhui Province, professor. His research interest includes water resources. 相似文献
19.
Using five-group dating of the fossil by Uranium series age method shows that the age of Nanjing Homo Erectus is between 280–430 ka B. P. Combining with the analysis of fossil mammalian form Stegodon, Sus. Lydekkeri Zdansly, M. pachyosteus Young, P. grayi Zdansky and E. SanmeniensisTeilhard et Pive teau, which are located in the same stratum, the authors thinks that the Nanjing Hmo Erectus may have lived in the late Mid-Pleistocene (about 350 ka B. P.). Based upon the spores and pollen in the cave sediments of
the area, we can find that most of spores and pollen are subtropical and warm temperature types. For instance, broad leaf
trees which are fond of warm climate, including Cunning hamia, Jsuga and Pinus, as well as Morus, Carpinus and Ptendium. Among the above spores and pollen, only Tsuga, Liquidambar, Betula, Ulmus and Salix are the remainders of Humid-hot environment from the Tertiary period. Above evidences illustrate that the living environment
of the Nanjing Homo Erectus not only was not cloder but also was not drier than the Peking Man’s. It could be said that dry climate and the ice age of
the Mid-Pleistocene didn’t undergo this area. As for the manner of the Homo Erectus’s making stone artifact and using fire, because now we have not found the evidence of the stone artifact and the ash, the futher
excavation to the talus of the Huludong cave should be needed.
Foundation item: Under the auspices of the National Natural Science Foundation of China (49771075) and Testing Foundation
by the Modern Analysis Center of Nanjing University.
Biography: ZHU Cheng (1954–), male, professor. His major research interests include environmentul evolution and global changes. 相似文献
20.
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