Abstract: Growth strata (i.e. progressive unconformities) are linked to a particular structure at depth and a record for different tectonic and sedimentation processes. they locate in foreland basins on the fronts of fold and thrust belts and exhibit extremely varied attitudes. The inherent synchroneity of growth strata and coupled fold or fault activity make growth strata crucial to interpret fold-and-thrust geometry and kinematics. On the balanced cross-section the sequences of growth strata have characteristic wedge-shaped sedimentation. In coeval depositional systems, fault-bend folding, fault-propagation folding and detachment folding are interpreted as the dominant mechanisms. The other modes of folding are recognized later in the 1980s,for example, Trishear folding and Chester and Chester folding, and so on. Though several types of theoretical behavior are expected, all growth strata can be grouped into two fundamental mechanisms: hinge migration and Limb rotation. Growth strata result from a simultaneous interference of several processes such as tectonics, sedimentation and erosion. The interplay between tectonic and surface processes has been shown to constrain the evolution of orogens through a feedback mechanism, the competition between tectonic uplift and shortening, syntectonic sedimentation rate and syntectonic erosion rate controls the final shape and the occurrence and geometries of fault breakthrough in thrust-related anticlines. According to variety of limb and hinge, synsedimentary wedge, variety of strata occurrence and thickness and regional geological setting, growth strata can be identified. In the future, the study of thrust-related folding processes within folds and thrusts belts will be developed by multi-models and ways. Synchroneity and continuity of growth strata and coupled fold or fault activity can be depicted accurately. Based on the present work and good examples of growth strata, paleomagnetic stratigraphy can provide some important information about chronology and tectonic process. Through reviewing briefly the importance, geometry and kinematics of growth strata, we conclude that the Sikouzi section should be a molasses basin occurring in the front of thrust-fold mountain belt where there exist growth strata and progressive unconformities. However,detailed investigation should be done on this in the future.

Key words: growth strata, progressive unconformitie, thrust-fold mountain belt, foreland basin, Sikouzi section

摘要： 生长地层记录了大量的构造变形和沉积历史信息,主要形成于逆冲-褶皱造山带前陆盆地边缘,在前陆盆地生长构造(如生长逆断裂-褶皱带)翼部或顶部与褶皱构造变形同期沉积的地层,是构造运动与沉积作用同时进行的产物,在构造横剖面上,整个生长地层序列在褶皱翼部具有楔形几何状态。根据其形成方式的不同,可以分为断层转折褶皱作用和断层传播褶皱及滑脱褶皱作用等。生长地层的最终形态受各种地质作用影响,其中主要因素是构造变形、沉积速率和侵蚀作用,三者之间在生长地层形成过程中通常具有“复合”作用。通过生长地层的详细研究,可以建立同构造生长地层模式,而广泛应用于确定前陆逆冲-褶皱带与相应地层的时代、变形速率,分析与逆冲推覆断层相关的褶皱几何形态,以及建立动力学模式等。生长地层的野外识别一般可从褶皱翼部和枢纽变化、翼部同沉积楔体、地层产状和厚度变化以及区域资料收集对比等几方面来综合分析,同时采用多模式、多手段的室内分析将是研究生长地层最为有效的方法,也是今后的重点发展方向。通过对生长地层的识别标志和模式的进一步认识,初步分析了六盘山山前宁夏固原寺口子剖面,认为寺口子盆地为逆冲-褶皱造山带前陆磨拉石盆地,其内可能存在有生长地层和生长不整合,但需要进一步详细研究。

关键词: 生长地层, 生长不整合, 逆冲-褶皱造山带, 前陆盆地, 寺口子剖面