摘要
在中国西北地区的高山、高原与内陆干旱沙漠的交界带(半干旱区),沉积有一定厚度的晚第四纪黄土,厚度从几米到40～50m,1.5×10~6a以来的黄土地层可分为6段,分别为:S_0,全新世古土壤,时代<8.5×10~3a.B.P.;L_(1-1),上马兰黄土层,0.85～2.5(2.1～2.7)×10~4a.B.P.;Sm,马兰黄土中部古土壤层,2.5×10~4～5.4×10~4a.B.P.;L_(1-2),下马兰黄土层,5.4×10~4～8×10~4a.B.P.;S_1,离石黄土顶部古土壤层,即末次间冰期古土壤,8×10~4～1.4×10~5a.B.P.;L_2,离石黄土,即倒数第二次冰期形成的黄土,>1.4×10~5a.B.P.黄土与石土壤层的磁化率值相差数倍。黄土地层磁化率曲线可做为气候变化的代用指标。位于兰州附近的临夏黄土地层剖面,其环境变化信息记录的精度可与深海和南极Vostok冰芯对比。
There is late Quatenlary loess deposited at contacting area between high mountains,plateau with inland desert, the thhickness of the loess strata are several meters to 40 or 50m, in northwwest of China.The late Quaternary loess strata can be divided into six parts:that is,S_0, Holocene paleosol,age<8500. B. P.;L_(1-1), the up—part Malan loess, 8500—25000(21000—27000)a. B. P.; Sm, the paleosol developed in Malan loess,25000—54000a. B. P.;L_(1-), the down—part Malan loess, 54000—80000a. B. P.; S1, the top paleesol at Lishi loess, i. e., the last interglacial paleosol, 80000—140000a. B. P.; L_2, Lishi loess, i, e., the Penultimate glacial loess,>140000a. B. P..The magnetic susceptibility differences between loesses and palcosols are several times. The magnetic susceptibility curve of the loess strata can be as a representative index for paleoclimatic change, the magnetic susceptibility curve of Linxia loess section near Lanzhou is similar to delta oxygen curve in deep—sea core(RC11—120)and Vostok deep—ice core in Antarctica.
出处
《干旱区地理》
CSCD
北大核心
1992年第4期20-26,共7页
Arid Land Geography
基金
国家基金
国家教委博士点基金
关键词
黄土
地层
第四纪
环境
西北地区
Loess strata, Late Quaternary environment, Northwrst of China
