滇川西部构造带的四川运动

    THE SICHUAN OROGENY IN WESTERN YUNNAN AND SICHUAN

    • 摘要: 四川运动系李春昱教授于1950年正式创建,指白垩纪与第三纪之间的一次地壳运动,认为是中生代最强烈的一幕造山运动,其时间与北美的拉惹米运动相当。为了强调它的重要性还进一步将阿尔卑斯旋回划分为印支运动、燕山运动和四川运动三幕。三十多年来,此概念一直为广大地质界所熟悉和广泛引用。然而,近年来有人对其提出异义,并撰文予以否定,建议废除此名。于是,引起地质界意见纷云,出现了过分强调和彻底否定四川运动的争论。为了考察和探讨该运动的客观情况及其实质,本文就滇川西部的一些实际资料,对四川运动的存在、性质、强度及其构造意义提出一些粗浅认识。

       

      Abstract: Recent data clearly indicate that the Sichuan orogeny did take place in western Yunnan and Sichuan and comprises two episodes. The early episode took place between the Late Cretaceous and Paleocene. According to a synthetic analysis of the characteristics and distribution of unconformities, stratigraphic breaks and magmatic intrusion, the tectonic activity in this episode was mainly expressed by large-scale fold-downwarping, uplifting and faulting. The metamorphism and fold movement took place only along the fracture zone. he late episode took place between the early-mid Eocene and late Eocene. All characteristics indicate that the tectonic activity had a large scale and influenced broad areas. It was represented by remarkable fold and fault movements, followed by large-scale uplift of the earth’s crust. Magmatie intrusion occurred in both episodes. The tectonic activity became weak and uplifting gradually predominated over folding from south to north and from west to east. It had a tendency to become weak from the center of the region to the edges. Obviously, the Sichuan orogeny is closely related to the Tethyan tectogenesis. Undoubtedly, the driving force must come from the margins of the Tethys. The Sichuan orogeny represents a short period of relative stability after the strong Yanshanian orogeny and the eve of the collision between the Indian plate and the Eurasian plate as well as a transition period. So the Sichuan orogeny does not belong to the Yanshanian subcycle and was the beginning of the Himalayan subcycle.It was not a continuation of the Yanshanian orogeny, but the prelude of the Himalayan orogeny. Its tectonic significance lies in its forming a connecting link between two subcycles, i.e.the preceding and the following.

       

    /

    返回文章
    返回