Grain size is one of the useful indices in the lacustrine sedimentary research. By directly indicating the water impetus during the sedimentary period, the grain size of lake sediments indirectly reflects the supplied water volume changes of the lake. Because the lake water volume is greatly influenced by climatic factors, such as precipitation, temperature and induced glacier melting water, the grain size provides more information to elucidate the environmental changes. By the analyses of the grain size parameters and the comparison with other proxies of the Chen Co sediments, four stages of environmental changes since ca. 1400 years ago have been distinguished. 1) Ca. 593~821 A.D. was a high lake level period accompanied by frequent fluctuations. It implies relatively wet climatic conditions with multi time alternative changes. 2) Ca. 821 1343 A.D. was a long and stable wet period, during which the lake enlarged and the lake level rose. 3) Ca. 1343 1892 A.D. was a climatically complex period. The inflow water violently increased around ca. 1602 A.D. while the lake was in the shallow water status in other periods. It suggested that the supplied water of the lake was relatively weak. 4) Ca. 1892 1998 A.D. was another stable period with the light lake level variations. Ca. 1892 A.D. was an obvious borderline for showing the supplied water impetus changes. These environmental changes reflected by the grain size of Chen Co lake sediments were well supported by other proxies and proved by other research results.
WANG Jun bo, ZHU Li ping
. Grain-size Characteristics and Their Paleo-environmental Significance of Chen Co Lake Sediments in Southern Tibet[J]. PROGRESS IN GEOGRAPHY, 2002
, 21(5)
: 459
-467
.
DOI: 10.11820/dlkxjz.2002.05.007
[1] 姚檀栋,刘晓东,王宁练.青藏高原地区的气候变化幅度问题[J].科学通报,2000,45(1):98-106.
[2] 冯松,汤懋苍,王冬梅.青藏高原是我国气候变化启动区的新证据[J].科学通报,1998,43(6):633-636.
[3] 中国科学院青藏高原综合科学考察队.西藏河流与湖泊[M].北京:科学出版社,1984.
[4] 陈敬安,万国江,徐经意.洱海沉积物粒度记录与气候干湿变迁[J].沉积学报,2000,18(3):341-345.
[5] 万国江.现在沉积的210Pb计年[J].第四纪研究,1997(3):230-239.
[6] 万国江.现在沉积年分辨率的137C s计年——以云南洱海和贵州红枫湖为例[J].第四纪研究,1999(1):73-80.
[7] Penn ing ton W,Cam b ray R S,F isher E M.O b servation on lake sed im en ts u sing fallou t 137C s as a tracer[J].N atu re,1973,242:324-326.
[8] 谢又予等.沉积地貌分析[M].北京:海洋出版社,2000.3.
[9] 孙千里,周杰,肖举乐.岱海沉积物粒度特征及其古环境意义[J].海洋地质与第四纪地质,2001,21(1):93-95.
[10] 李原,李任伟,尚榆民等.云南洱海的环境沉积学研究——表层沉积物的粒度分布、水流方向和能量[J].沉积学报,1999,17(增刊):769-774.
[11] 中国科学院兰州分院,中国科学院西部资源环境研究中心著.青海湖近代环境的演化和预测[M].北京:科学出版社,1994.8.
[12] 陈敬安,万国江.云南洱海沉积物粒度组成及其环境意义辨识[J].矿物学报,1999,19(2):1752182.
[13] 王苏民,李建仁.湖泊沉积—研究历史气候的有效手段——以青海湖、岱海为例[J].科学通报,1990,35(1):54-56.
[14] Zhu L ip ing,Chen L ing,L i B ingyuan et al.Environm en tal changes reflected by the lake sed im en ts of the Sou thHong shan L ake,N o rthw est T ibet[J].S cience in Ch ina,2002,45(5):430-439.
[15] 孙永传,李蕙生.碎屑岩沉积相和沉积环境[M].北京:地质出版社,1986.
[16] 中国科学院青藏高原综合科学考察队.西藏冰川[M].北京:科学出版社,1986.10.
[17] 朱立平,陈玲,张平中等.环境磁学反映的藏南沉错地区1300年来冷暖变化[J].第四纪研究,2001,21(6):520-527.
[18] 李元芳,朱立平,李炳元.介形类记录揭示的藏南沉错地区近1400年来环境变化[J].地理学报,2002,57(4):待发.
[19] 沈吉,张恩楼,夏威岚.青海湖近千年来气候环境变化的湖泊沉积记录[J].第四纪研究,2001,21(6):508-513.
[20] 竺可桢.中国近五千年来气候变迁的初步研究[J].中国科学,1973(2):168-189.
[21] 张丕远,王铮,刘啸雷等.中国近2000年来气候演变的阶段性[J].中国科学(B辑),1994,24(9):998-1008.
[22] 张德二.我国“中世纪温暖期”气候的初步推断[J].第四纪研究,1993(1):7-15.
[23] 王绍武,叶瑾琳,龚道溢.中国小冰期的气候[J].第四纪研究,1998(1):54-62.
[24] 施雅风,姚檀栋,杨保.近2000a古里雅冰芯10a尺度的气候变化及其与中国东部文献记录的比较[J].中国科学(D辑),1999,29(增刊1):79-86.