中文摘要：

采用Leica-DMRX偏光显微镜对喇家遗址剖面不同土壤发生层的薄片进行了观察和影像定量分析，旨在阐明青海民和官亭盆地喇家遗址古耕作土壤层和现代耕作土壤层的发育过程和微形态特征。齐家文化时期古耕作土壤层（Ah2／Ap4）的微形态特征主要表现为粗颗粒，呈现圆状一次圆状，C／F15μm值呈现低值，排列显示弱定向，常见亚胶膜状和团聚状淀积黏土，大量的针状方解石微晶分布在孔隙边沿，孔隙度较高，主要是以圆形孔洞、囊孔占优势，孔隙壁光滑。辛店文化时期古耕作土壤层（Ah1／Ap3）与Ah2／Ap4层的主要微形态特征相似，只是C／F15μm值呈现相对高值，亚胶膜状和团聚状淀积黏土比例减少。相比于古耕作土壤层（Ah1／Ap3，Ah2/Ap4），现代耕作土壤层（Ap1）主要表现为粗颗粒，呈现次棱角状一次圆状，含有大量浓聚物状残积黏土和极少量亚胶膜状淀积黏土，含有大量的针状方解石微晶，孔隙度较低，且C／F15μm值趋于升高。古耕作土壤层Ah2／Ap4和Ah1／Ap3皆为黑垆土，它们分别是在全新世中期大暖期的环境背景之下，齐家文化时期和辛店文化时期人类简单耕作和古生物气候条件下的产物。Ap1层为淡灰钙土，它是距今约1500年以来人类施加土粪、农业耕作和沙尘暴堆积的综合产物，其特征主要受到人类活动强度和方式的控制。

英文摘要：

The Lajia Ruins is a large-scale settlement of the Qijia Culture （4 200 ~ 3 950 a BP） . Archaeological excavations have exposed a shocking picture of prehistorical catastrophes in the Lajia Ruins in the Guanting Basin, Minhe County, Qinghai Province. The causes of the prehistorical catastrophes in the Lajia Ruins have become a hot topic in the field of environmental change. Unfortunately, so far little has been reported on development processes and micromorphological features of the ancient plow layer of the paleosol in comparison with the plow layer of the modern soil in the Lajia Ruins. Therefore, a comparative study was carried out on micromorphologies of the two soils in an attempt to reveal their development processes and micromorphological features. Micromorphological features of different genetic layers of the soil profile in the Lajia Ruins were observed under a Leica-DMRX petrographic microscope, and their images was quantitatively measured using Leica-Qwin V3 software. The main micromorphological features of the ancient plow layer of the paleosol of the Qijia Culture （ Ah2/Ap4 ） are round to sub-round coarse grains, low C/F15μm, poorly directive permutation, abundant illuvial clay hypocoatings and concretion, abundant needle-shaped secondary- calcite at edge of pores, high porosity consisting mainly of smooth circular pores and bag holes. The ancient plow layer of the paleosol of the Xindian Culture （ Ah1/Ap3 ） is quite similar to the ancient plow layer of the paleosol of the Qijia Culture （ Ah2/Ap4 ） in micromorphological features, except for C/F15μm, which is higher in the former, and proportion of illuvial clay, which is lower in the former. The main micromorphological features of the ancient plow layer of the paleosol （ Ah2/Ap4, Ah1/Ap2） are different from that of the modern plow layer （ Ap1 ） in the Lajia Ruins. The Apl horizon is characterized by sub-angular to sub-round coarse grains, abundant residual clay concretion and a little amount of illuvial clay hypocoatings, ab