构造-沉积分异原理及其地质意义*

构造-沉积分异是地球表层的常见地质现象,发生于沉积盆地、造山带与克拉通等岩石圈构造单元,表现为岩石圈的深、中、浅层始终发生着沉积物、流体、能量与力的交换与分异过程。文中从物质组成、时空分布与力学机制等方面阐述构造-沉积分异的基本特征,并以中国沉积盆地为例进行分析。作者首先将构造-沉积分异定义为“由构造应力、热力、重力、地幔动力等因素引起地表地形差异,从而导致沉积物源、搬运体系与沉积作用变化的过程”;认为构造-沉积分异发生在不同尺度的洋-陆系统、盆-山系统、隆-坳系统、凸-凹系统与高-低地貌系统,受基底结构、强度与活动性的明显控制,构造应力、重力、热力、地幔动力等控制了该分异机制; 强调随时间演变出现构造-沉积分异演化旋回,表现为伸展期裂陷向聚敛期隆坳转变,碳酸盐岩分异台地向统一台地转变。上述控制因素与机制在时空上可以发生复合,导致多类构造-沉积分异作用出现。研究构造-沉积分异作用,可以为重建地球历史、加快矿产资源勘查和改善人类宜居环境做出贡献。

Principles of tectonic-depositional differentiation and its geological significance

The tectonic-depositional differentiation is a common phenomenon on the Earth surface. It takes place in the lithospheric components such as sedimentary basins,orogenic belts,and cratons. Sediments,fluids,energy,and forces are always changing and differentiating with each other on shallow,intermediate,and deep layers of the lithosphere. From a view of the material composition,spatio-temporal distribution,and mechanic processes,the paper discusses basic features of the tectonic-depositional differentiation in detail,taking the Chinese sedimentary basins as an example. It is defined as geomorphic differences on the Earth surface,which result from tectonic,thermal,gravitational processes,and mantle dynamics,which give rise to the variations in source,routing system,and deposition and fill. It takes place on variable scales that ranges from ocean-continent,basin-orogenic belt,uplift-sag,high-depression systems,to high-and-low relief geomorphic systems. The basement framework,strength,and moving style have marked controls upon the different scale of differentiation. The tectonic stress,gravitation,thermal stress,and mantle dynamics control the differential mechanisms. It exhibits the differentiation cycle with the geological evolution,transforming from rifts and depressions during the extension period into uplifts and sags during the compression period,especially for carbonate platforms changing from the rifted differential platform to the compressive unified platform. All these factors and mechanisms can be interlinked and play roles altogether in the geological spatio-temporal framework,giving multi-varied tectonic-depositional processes. It is a key basis to reconstruct the earth history,to boost the exploration of the ore deposits and resources,and to improve the habitable environments for humankind.