川西高原甘孜黄土地层学  

The Ganzi Loess Stratigraphy in the West Sichuan Plateau

作　　者：蒋复初[1] 吴锡浩[1] 肖华国[1] 赵志中[1] 田国强[1] 刘科[1] 

机构地区：[1]中国地质科学院地质力学研究所

出　　处：《地球学报（中国地质科学院院报）》1997年第4期413-420,共8页Acta Geoscientia Sinica

基　　金：地质矿产部"九五"重点基础研究项目;中国科学院黄土与第四纪地质国家重点实验室基金

摘　　要：本文初步研究了甘孜黄土地层，实测了甘孜县城西南郊新市区和满地两剖面，它们分别厚２３．７ｍ和２６．０ｍ。根据岩性、磁性地层特征、磁化率、ＣａＣＯ３质量分数测定和热释光测年结果，甘孜黄土可划分为冰后期Ｓ０复合古土壤，末次冰期Ｌ１复合黄土和末次间冰期Ｓ１复合古土壤等３个地层单位。布莱克反向极性亚时记录于底部Ｓ１ＬＬ１黄土中。甘孜黄土沉积始于晚更新世早期，大约为１２０ｋａＢＰ。甘孜黄土的磁化率变化反映了最近１２０ｋａ来的高原季风演化和气候环境变迁，６个磁化率高值段指示了６个夏季风环流增强的时段，６个磁化率低值段则代表了６次夏季风减弱时期。甘孜黄土可与黄土高原同期黄土进行对比，但又存在明显差异。There is a wide distribution of the eolian loess in West Sichuan Plateau. A preliminary study of the loess strata in Ganzi area was carried out in this paper, in which two profiles situated at Xinshiqu and Mandi in the southwest suburbs of the Ganzi City were measured, with 23.7 m and 26.0 m thick respectively. According to the characteristics of lithology and magnetostratigraphy, susceptibility, CaCO 3 content and thermoluminescent dating, the loess sequence can be divided into three stratigraphical units as paleosol S 0, loess L 1 and paleosol S 1, which were formed in the postglacial period, last glaciation and last interglaciation respectively. The compound paleosol S 1, with 5.1 m thick, is composed of three secondary stratigraphical units as paleosol S 0SS 1, loess S 0LL 1 and paleosol S 0SS 2. The loess L 1 can be subdivided into seven secondary stratigraphical units, including loesses L 1LL 1, L 1LL 2, L 1LL 3, L 1LL 4 and compound paleosols L 1SS 1, L 1SS 2 and L 1SS 3. The paleosol S1 is not exposed thoroughly in the profiles and can be only subdivided into two secondary stratigraphical units, namely paleosol S 1SS 1 and loess S 1LL 1. The Blake subchron recorded in the S 1LL 1. The deposition of the Ganzi loess began at the early of Late Pleistocene, about 120 kaBP. The susceptibility of loess stratais that regarded as a measurement reflected strength of pedogenesis and rate of sedimentation is usually a classical proxy index indicated the summer monsoon changes in the Loess Plateau , and it can show the summer monsoon changes in the Qinghai_Xizang Plateau as well. The evolution of plateau monsoon and the change of climate environment can been brought to light by the susceptibility of the Ganzi loess strata in the last 120 ka, in which six strengthening of the summer monsoon circulation are shown by the higher values of susceptibility and six weakening are shown by the lower values.

关 键 词：黄土 地层学 磁化率 晚第四纪 青藏高原 

分 类 号：P534.63[天文地球—第四纪地质学]