三江平原位于黑龙江、松花江和乌苏里江的汇流地带,具有完整而独特的自然地理结构。探索这一结构的特点和形成过程,对该区的合理开发及综合治理具有重要意义。构成三江平原地理环境的因子较多,影响其发育过程的因素复杂,其中第四纪地壳运动是一个重要因素。对此,本文试作初步探讨。

The Quaternary crustal movement of Sanjiang plain has been mainly submer ging successively on a large scale,and the maximum depth of the submergence in that region is believed to be nearly 300 meters.The rate of [submergence is 1.7 mm per year.Recently it mainly continues to submerge,but it indicates a tendency of reduction in range and of weakening in the activity of crustal movement gradually.The neotectonic movement provinces of Sanjiang region may be divided into four first-class sections and eight second-class sections:Ⅰ₁ and Ⅰ₂ The Qianjin-Hanchonggou [and the Juncuan-Seibin province,showing maximum range of submergence in the Pleistocene and a slow submerge in recent time.Ⅱ₁ and Ⅱ₂ The drainage area of Rouli river and Anbang river,showing the middle range of submergence in the Pleistocene and a glow submerge in recent time.Ⅲ₁ and Ⅲ₂ The Huacuan-Hongwei and Hanchonggou province,showing middle range of submergence in the Pleistocene and a slow uplift in recent time.Ⅳ₁ and Ⅳ₂ The Jiamusi-Haiqing province,showing minimum range of submergence in the Pleistocene and a slow uplift in recent time.It is noticeable that the formation of continental rift valley system caused by Pacific plate underthrusting the continent is the principal mechanism which formed the rift of the Sanjiang plain.