摘要
笔者通过国内第四纪盐湖沉积的长期实地考察以及盐湖长期科学观察站的实验研究，并结合国内外大量盐湖沉积实验研究资料，以比较盐湖沉积学的理论和方法，将盐湖沉积划分为冷相、暖相和广温相，揭示现代全球盐湖水化学类型分带与气候分区的一致性；指出我国第四纪存在6次干旱（成盐）扩张期；识别出中国第四纪干旱中心19个明显的强冷偏湿-冷干事件及8个明显的暖偏湿-暖干事件，并推算其古气温变化范围。
Saline lake deposits are the product of the physicographical and geological environments where they are located. All the stages, from their formahon to development retain the informahon of their surrounding envirorunents, including the information of the stage of salinizahon that lacustrine and swampy facies are short of Therefore salt deposits have the holographic characterishcs for the changes of lacustrine environment. Especially very mick salt deposits record related information about frequent altemation of different saline deposits and dry/wet and cold/ warm paleoclimahc changes. Quaternary saline lakes are widely distributed in China. Thirteen provinces and autonomous regions have recent saline lakes and underground clashc brine lakes. In some areas, saline lake deposits occur throughout the Quatemary and have the characterishcs of multiple stages, long term, continuity of deposihon,rhythmicity of freshening and salinizing and direchonal migration and spreading.Saline lake deposits are the product of arid (warm or cold) climate zones. But there are differences in saline minerals and assemblages between them. So the assemblages of saline deposits that reflect different paleotemperatures can be treated as an effective indicahon for recovering paleoclimate. On the basis of this knowledge and the theory and metrhod of salinology (the study of saline lake science), saline minerlas can be divided into three types：cold saline mineral, warm saline mineral and eurythermal saline dineral. In combination with the relations of cold and warm recent saline lake sediments with climate where they are located and rules of salting-out for different types of salt-water system, some typical cold and warm climate factors of continental salt deposits can be stimmarized as follows: (1) Typical cold-stable mirabilite deposit： It is located in subarid or arid zones of the frigid zone, subfrigid zone and medium temperate zone. The average annual temperature is below zero (below - 7-0℃). (2) Typical warm-stable thenardite deposit or fluorite and bloedite-bearing bed：it is located in arid areas of the subtropical-tropical zone and equator. The average annual temperature is 16~ 25℃. (3) Transitional deposit：It is composed mainly of eurythermal mineral trona, which reflects a larger range of temperatures and located in the warm-medium temperate zone. The average annual temperature is approximately 6-8℃ and over.On the basis of the hydrochemical data of 350 saline lakes in China, the authors have compiled a map of hydrochemical zones of saline lakes of China. It shows： (1) Saline lake regions of chloride-sulfate type, mainly located in arid or extremely arid areas. (2)Saline lake regions of sodium sulfate subtype, mainly located in arid zones of different climatic zones. (3) Saline lake regions of carbonate type, located between the above tWo types of zones. They are always in accordance with the subarid zones of the temperate, subtropics or tropic zones, or with the alternating-area of dry and wet monsoons.From the angle of evolution of saline lake deposits, the region of Qaidam-eastern Tarim in western China is the center of saline deposits since the Quaternary in China.From an analysis of air temperatures, there have been 9 violent cold and dry events,10 cold and slightly dry events and 8 warm and slightly dry events since the Quaternary. The average air temperature of the violent cold and dry events is 6-11℃ lower than that of the present And that of the warm and slightly dry events is 8-10℃ higher than that of the present.Since Quaternary, there have been six spreading stages of arid climate (salinization) with Qaidam-eastern Tarim as the center： Stage I (2.36-2.00Ma B. P.); Stage II (1.62-1.00Ma B. P.), Stage III (0.90-0.60Ma B. P.); Stage IV (34 000 or 31 000-21 000a B. P.), Stage V (18 000 - 5 000a B. P.), Stage VI(4 500a B. P. - the present day).
出处
《第四纪研究》
CAS
CSCD
北大核心
1998年第4期297-307,共11页
Quaternary Sciences
基金
国家自然科学基金!49833001
关键词
盐湖沉积
干旱
气候事件
古气候
第四纪
saline lake deposition, spreading stage of arid climate (salinization),climatic event
