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1.
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. 相似文献
2.
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
3.
Palynological record of paleovegetation change during holocene at North tumd plain 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
4.
Jinglu Wu 《中国地理科学(英文版)》1997,7(3):229-235
The hole RM, the deepest one fully obtained core in the Qinghai-Xizang Plateau, situated in the depositional center of the
Zoige Basin (33°57′N; 102° 21′E) in the northeastern Qinghai-Xizang Plateau with a depth of 310.46 m. From 14C dating and paleomagnetic stratigraphic study, the core RM can date back to 900 ka B.P.. In this paper we analyzed the compositions
of δ18O and δ13C in various carbonates can date (snail, obstrode, chemical carbonate) in core RM and discussed preferably the paleoclimatic
record by the proxies of δ18O and δ13C of chemical carbonate (authicarbonate) from core RM in the past 140 ka. The results showed that the values of δ18O in various carbonates are generally identical, and the values of δ13C in it are inconsistent, while there exist better relativity. The studies also demonstrated that there was a negative correlation
between δ18O and δ13C of authicarbonate in core RM in the past 140 ka, showing that the changes of δ18O values were mainly relative to the water temperature. According to above, the climatic evolutionary sequence were rebuilt
in the past 140 ka in the region. 相似文献
5.
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
6.
Based on the new data of the Quaternary along the coast of Hainan Island, China, this paper puts forward that the Holocene in Hainan Island can be divided into four formations: Wanning formation (Q41), Sanya formation (Q42-1), Qiongshan formation (Q42-2) and Ledong formation (Q43). Spore-pollen analysis shows that there are 6 spore-pollen zones existed, reflecting two cycles of climatic fluctuation from warm-dry to hot-humid. The climax of hot-humid period occurred 6,000-5,000 years B.P.. Based on the 14C dating data of the 38 samples representing the positions of ancient sea level, a breakthrough curve representing the sea level change during the Holocone is obtained, in which , a sea level change caused by tectonic movement is subtracted. Two cycles of rise-drop of sea level with three periods of high sea level were found. The period with the highest sea level is some 6,000-5,000 years B.P.. According to the rise-drop rate of sea level, four periods of the sea level change can be distinguished in the 相似文献
7.
A 6.2 m thick core of Gucheng Lake sediment provided a 3600 years record of climate change. The contents of the TOC in the
core changed from 2.63% to 8.48%, and the δ13C values of organic matter were from −21.54% to −27.3%. The TOC/TN ratios indicated that the organic materials in sediments
were from lake plankton and land-derived plants.
The 2.9–22 m core interval with high TOC/TN ratios, low δ13C values and low contents of TOC indicated a cold climate stage. The 6.2–5.5 m and 0.4–0.1 m intervals were characterized
by low TOC/TN ratios, high δ13C values and high contents of TOC, and reflected temperate climate stages.
Project 49372129 supported by NSFC. 相似文献
8.
Sand wedge is formed under the conditions of coldclimate, and is an important basis for reconstructingpaleoenvironment (LI et al., 1990; WANG, 1991 ). Ithas been reported constantly over the last 20 years inthe Qinghai-Xizang (Tibet) Plateau (GUO, 1979; CUl,1983; XU et al., 1984; LIANG et al.,, 1984; PAN etal., 199 ) and North China (YANG et al., 1983; DONGet al., 1985) and Northeast China (GUO et al.,1981 ). We also found fossil sand wedge groups formedin the end of the Late P… 相似文献
9.
Information on the palaeoenvironment from Late Pleistocene to Holocene in northwestern Yannan Plateau has been deduced from a study of a 28.81m-long core taken from Napahai Lake.The results from Relative Brightness In-dex(RBI) as well as those from the lithological analyses of bulk sediments,total organic carbon and granulometric analy-ses have been used to reconstruct the environmental and climatic evolution of the area.The ages were provided by three ^14C datings.The record suggested a climate fluctuation between warm-dry and cool-wet from ca.57 to 32ka B.P.which led a shallowing and swamping of the lake.The water level again increased quickly at ca.32ka B.P.,reached itˊs peak during LGM(Last Glacial Maximum,ca.18-20kaB.P.)and remained relative high until ca.15kaB.P.The high wa-ter level at LGM is attributed to cold-wet conditions.The area experienced an abrupt and unstable climatic changes dur-ing the transition period form 15 to 10ka B.P.with a dominated littoral environment.Awarm-dry climate led to the contrac-tion of the lake during the Holocene and reed-swamps became dominant..After a minor wet-cool pulse during the Late Holocene,the modern climate became to be established. 相似文献
10.
施雅风 《中国地理科学(英文版)》1994,4(2):186-192
PROFESSOR ZHU KEZHEN OPENING UP A PATH FOR RESEARCH ON CLIMATIC CHANGE IN CHINA ShiYafeng(施雅风)(LanzhouInstituteofGlaciologyan... 相似文献
11.
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
12.
Huang Peihua Peng Zicheng Jin Sizhao Liang Renyou Quan Yucai Wang Zhaorong 《中国海洋湖沼学报》1989,7(1):79-88
Electron Spin Resonance (ESR) dating is a relatively new technique applicable also to the dating of materials from littoral
zones and shallow sea regions, such as shells, corals, bones and teeth, foraminifera, diatoms, etc. ESR dating can span the
time interval between the older limit of14C dating and the younger limit of the K−Ar dating, an interval of 103–106 years. Therefore, ESR technique is very suitatie for the measurement of the age of Quaternary sea—level changes. This paper
gives some samples’ results by ESR dating from Early Pleistoncene to Holocene.
The Quaternary sea—level changes in China were mainly eustatisms that corresponded to the paleotemperature variation. We have
just begun study on the18O Paleotemperature in our continental area. Preliminary results show the temperature curve of the stalagmitic growth in caves
corresponds well to the sea—level changes in 76–55×103 years B. P. ESR dating and studies of the18O Paleotemperature in East China will raise studies on Quaternary sea—level changes to a higher scientific basis. 相似文献
13.
Decomposition of algal lipids in clay-enriched marine sediment under oxic and anoxic conditions 总被引:1,自引:1,他引:0
A series of laboratory incubation experiments were conducted to examine the decomposition of algal organic matter in clay-enriched
marine sediment under oxic and anoxic conditions. During the 245-day incubation period, changes in the concentrations of TOC,
major algal fatty acid components (14:0, 16:0, 16:1, 18:1 and 20:5), and n-alkanes (C16–C23) were quantified in the samples. Our results indicate that the organic matters were degraded more rapidly in oxic than anoxic
conditions. Adsorption of fatty acids onto clay minerals was a rapid and reversible process. Using a simple G model, we calculated
the decomposition rate constants for TOC, n-alkanes and fatty acids which ranged from 0.017–0.024 d−1, 0.049–0.103 d−1 and 0.011 to 0.069 d−1, respectively. Algal organic matter degraded in two stages characterized by a fast and a slow degradation processes. The
addition of clay minerals montmorillonite and kaolinite to the sediments showed significant influence affecting the decomposition
processes of algal TOC and fatty acids by adsorption and incorporation of the compounds with clay particles. Adsorption/association
of fatty acids by clay minerals was rapid but appeared to be a slow reversible process. In addition to the sediment redox
and clay influence, the structure of the compounds also played important roles in affecting their degradation dynamic in sediments. 相似文献
14.
Isotopic evidence for holocene climatic changes in Bosten Lake, Southern Xinjiang, China 总被引:2,自引:0,他引:2
ISOTOPICEVIDENCEFORHOLOCENECLIMATICCHANGESINBOSTENLAKE,SOUTHERNXINJIANG,CHINAZhongWei(钟巍)XiongHeigang(熊黑钢)DepartmentofGeograp... 相似文献
15.
1 INTRODUCTIONSincethe1980saseriesofresearchplanincludingIGBP(theInternationalGeosphere.BiosphereProgramme)havebeensetup,ofthem,PAGES(thePastGlobalchanges)isanimportantcoreproject.Thenaturerecordsofoceandeposit,terrestrial(loess,lakesandswamp)deposi… 相似文献
16.
Sun Dapeng 《中国海洋湖沼学报》1987,5(4):351-362
The Nei Mongol (Inner Mongolia) Plateau is one of the most important salt lake areas in China. Its trona deposits are well
known in the world.
The soda lakes spread mainly over the northern part of the Ordos Basin, the central part of the Eren Basin, the southeastern
part of the Hailar Basin and the Badain Jaran Desert are generally several to several dozen square kilometers, and surrounded
by sand dunes.
The salinity of soda lake brines is 200–350 g/l, the pH values, 9.09–10.67. The brines mainly consist of Na(K), Cl, SO4, CO3, and HCO3 of the Na(-CO3-SO4-Cl) type.
Trona deposits in soda lakes on the plateau always occur in “bull’s eye pattern” and are usually in two layers of natron,
mirabilite, halite and trona interbedded with black mud containing much illite clay and some gayllussite, dolomite and calcite.
Commonly, the soda lakes on the plateau were formed on the depressions from the beginning of early Holocene, but the trona
deposits were mainly precipitated under the low temperature in Mid-Holocene (as proved by our freezing experiments and sporo-pollen
analysis). 相似文献
17.
Itisoneofthefrontierfocusesinthefieldofglobleenvironmentalchangestoextractquantitativelypastclimaticsignalsfromlakesedimentrecords.Inthere-centdecadciousyearsaseriesofachievementsonre-buildingthesequencesofclimaticandenvironmentalevolutionsatvariouss… 相似文献
18.
Xinping Zhang 《中国地理科学(英文版)》1997,7(4):339-346
The relations between δ18O and temperature on the different time scales were analysed, according to the data from Tuotuohe (34°13′N, 96°25′E; 4533
m a. s. l.), Delingha (37°22′N, 97°22′E; 2981 m a. s. l.) and Xining (36°37′N, 101°46′E; 2261 m a. s. l.) in the Qinghai-Xizang
Plateau. The results show that the significance of d δ18O/dT on different time scales are different. The d δ18O/dT on the synoptic scale reflects the interdependent relation between δ18O and temperature in the short-term synoptic scale process; the d δ18O/d T on the seasonal scale reflects the relation between them whithin a year; and the d δ18O/d T on the climatic scale reflects the relation between them in the long-term climatic change. The calculated d δ18O/dT on climatic scale is very close to the theoretical values on the condition of advection transport for Tuotuohe Station. However,
there are great differences between the calculated and the theoretical values for Delingha and Xining stations. 相似文献
19.
Stable isotopes in aquatic food web of an artificial lagoon in the Hangzhou Bay, China 总被引:1,自引:0,他引:1
Stable isotope values, δ13C and δ15N, were determined for four primary producers and 19 dominant consumers in a small artificial lagoon located in Hangzhou Bay.
Based on these results the major pathways for energy flow and trophic structure of the artificial lagoon ecosystem were characterized.
The mean δ13C values for the 19 consumers ranged from −22.99‰ to −14.24‰. Apart from so-iny mullet Liza haematocheila, the other 18 consumers had intermediate δ13C values between those of epibenthic microalgae and particulate organic matter (POM). The results of a multiple source linear
mixing model (IsoSource model) indicated that 50% or more of the organic carbon in the tissues of most consumers was derived
from epibenthic microalgae. This indicated that these primary producers were the main food source fueling the lagoon food
web. The mean δ15N values for the 19 consumers varied between 4.93‰ and 12.97‰ and indicated four trophic levels in the lagoon. Four macroinvertebrates
and zooplankton represented the primary consumers, whilst the other 14 consumers occupied the secondary and tertiary consumer
levels. The 19 consumers were divided into three trophic guilds (detritivores/suspension feeders, omnivores and carnivores). 相似文献
20.
On the origin of rice agriculture in southern China and its propagation in East Asia 总被引:1,自引:0,他引:1
Zhenguo Huang 《中国地理科学(英文版)》1994,4(4):289-294
Based on the archaeological rice cultivation with the14C dating of about 4000–5000 a B.P. the author holds that the plain at the lower reaches of the Changjiang (Yangtze) River
is one origin of rice cultivation in Asia and the other is Allahabad of India. The propagation of ancient rice cultivation
in China can be divided into three stages, namely 4000–3000, 2635–2420 and about 1000 a B.P. It is inferred that there were
two ways for propagating rice cultivation from China to Japan. One was from lower reaches of Changjiang River to Kyushu by
sea way and the other was from Shandong Peninsula to southern Korea and then to Kyushu. The age of propagating rice cultivation
into Vietnam from South China is about 1000 a B.P. Being influenced by climatic changes since about 5000 a B.P. the propagation
of rice cultivation was stagnated for two times at least, for example, the three warm climatic stages and the two cold stages
were quite in correspondence with the propagation and stagnation stages of rice cultivation, respectively, in China. During
the ancient times the development of paddy rice was directive related to the fluctuation of sea level which is in keeping
with the climatic changes. 相似文献