沉积学报
沉積學報
침적학보
ACTA SEDIMENTOLOGICA SINICA
2000年
3期
327-335
,共9页
孙东怀%鹿化煜%David Rea%孙有斌%吴胜光
孫東懷%鹿化煜%David Rea%孫有斌%吳勝光
손동부%록화욱%David Rea%손유빈%오성광
黄土粒度分布冬季风西风带
黃土粒度分佈鼕季風西風帶
황토립도분포동계풍서풍대
loess grain size winter monsoon westerly
中国黄土的粒度分布由分布峰度较高、分选较好的粗粒组分和分布峰度较低、分选较差的细粒组分叠加组成;前者代表了冬季风盛行季节近距离低空搬运的粉尘物质,其粒度指示了东亚冬季风所主导的近地面气流的强度,它在全样中的含量可能反映了冬季风粉尘的沉积通量;细粒组分可能主要为常态存在的、由高空气流搬运的远源粉尘,代表了黄土高原原始粉尘的本底,它的粒度特征与北太平洋西风带粉尘基本一致,可能指示了主要由西风带控制的高空气流的强度。黄土的粒度分布函数可用代表这两个组分分布的两个WEIBULL函数的和函数表示。用实测粒度分布数据对分布函数进行拟合可计算出该分布函数的各参数,同时可获得黄土粒度的两个组分各自的分布函数及两个组分在总样中所占的百分比。
中國黃土的粒度分佈由分佈峰度較高、分選較好的粗粒組分和分佈峰度較低、分選較差的細粒組分疊加組成;前者代錶瞭鼕季風盛行季節近距離低空搬運的粉塵物質,其粒度指示瞭東亞鼕季風所主導的近地麵氣流的彊度,它在全樣中的含量可能反映瞭鼕季風粉塵的沉積通量;細粒組分可能主要為常態存在的、由高空氣流搬運的遠源粉塵,代錶瞭黃土高原原始粉塵的本底,它的粒度特徵與北太平洋西風帶粉塵基本一緻,可能指示瞭主要由西風帶控製的高空氣流的彊度。黃土的粒度分佈函數可用代錶這兩箇組分分佈的兩箇WEIBULL函數的和函數錶示。用實測粒度分佈數據對分佈函數進行擬閤可計算齣該分佈函數的各參數,同時可穫得黃土粒度的兩箇組分各自的分佈函數及兩箇組分在總樣中所佔的百分比。
중국황토적립도분포유분포봉도교고、분선교호적조립조분화분포봉도교저、분선교차적세립조분첩가조성;전자대표료동계풍성행계절근거리저공반운적분진물질,기립도지시료동아동계풍소주도적근지면기류적강도,타재전양중적함량가능반영료동계풍분진적침적통량;세립조분가능주요위상태존재적、유고공기류반운적원원분진,대표료황토고원원시분진적본저,타적립도특정여북태평양서풍대분진기본일치,가능지시료주요유서풍대공제적고공기류적강도。황토적립도분포함수가용대표저량개조분분포적량개WEIBULL함수적화함수표시。용실측립도분포수거대분포함수진행의합가계산출해분포함수적각삼수,동시가획득황토립도적량개조분각자적분포함수급량개조분재총양중소점적백분비。
Grain - size distribution of Chinese loess consistently shows bimode spectrum, which is composed of two dis-tinct components. The main component is coarse grain size with, large kurtosis and narrow distribution range,makes up main part of loess material. This main component is likely produced in the season when winter monsoondominate the paleoclimate of loess plateau, and therefore its grain size indicates East Asia winter monsoonstrength. The other grain size component has a wide distribution range, lower kurtosis and fine average grain size.This fine component probably represents the general dust base level of atmosphere over loess plateau, which pre-vails in most of the season. In some extension, it is genetically connected to the Northern Hemisphere westerly.Grain size distribution function of Chinese loess can be expressed with a sum of two Weibull distribution functionsthat represent two components of loess grain size. By fitting measured grain - size data to proposed distributionfunction, all parameters of the function can be estimated. Meanwhile, distribution function as well as the ratio ofthe two components can also be obtained.