中文摘要：

本文在鹤庆深钻孢粉分析的基础上，把各孢粉类型划分成不同的孢粉生态组，结合孢粉多样性指数，系统重建云南鹤庆地区2．78Ma以来的古气候演化所经历的8个大的阶段，与西南季风在滇西北地区8次大的变化相对应：即在2．729—2．608Ma和0．118Ma11．83kaBP期间，气候整体湿润，冬、夏季降水的季节性较强，反映西南季风相对较强盛；1．447-0．342Ma期间，气候整体逐渐变湿，冷暖、干湿变化幅度逐渐变大，气候组合特征逐渐变复杂，反映西南季风逐渐增强，其波动幅度也逐渐变大，并于0．991～0．342Ma期间达到最强盛，其波动幅度也最大；而在2．780—2．729Ma、2．608—1．447Ma和0．342-0．118Ma期间，气候普遍相对温暖干旱，西南季风相对较弱。

英文摘要：

Pollen types identified from the Heqing deep drilling core were divided into different pollen ecological groups in this paper. The changes of seven pollen ecological groups, two palynological diversity indices （D-total and H＇-total） and several high percentage pollen taxa are used to reconstruct the palaeoelimatic evolution of the Heqing Basin of Yunnan Province. The palaeolcimate went through eight major stages since 2. 780 Ma （late Pliocene to Holocene）. Corresponding with the palaeoclimate, the southwest monsoon experienced eight episodes in the northwest Yunnan Province. The climate was humid with a relative strong seasonality of precipitation in winters and summers during 2. 729-2.608 Ma and 0. 118 Ma-11. 83 ka BP, which reflected a relatively intense southwest mon- soon. During 1. 447-0. 342 Ma, the climate became gradually more humid with increasing amplitude between cold and warm condition and dry and humid condition, and the climatic patterns became more complex, which implies that the southwest monsoon gradually strengthened with increased fluctuating amplitude, and its intensity reached a peak with the maximal fluctuating amplitude in the period of 0. 991-0. 342 Ma. During 2. 780-2. 729 Ma, 2. 608-1. 447 Ma and 0. 342-0. 118 Ma, the climate was dominate by relative warm and dry conditions, implying a rather weak southwest monsoon.