前陆盆地沉降机理和地层模型

前陆盆地形成的主要原因是造山带负载导致的岩石圈挠曲。逆冲作用造成地壳增厚,造山带的巨大质量又导致下部岩石圈的区域均衡沉降,从而临近和平行于造山带发育了凹陷。另外,前陆盆地的演化也受到沉积物供应、盆地内沉积物扩散能力、岩石圈强度、造山带逆冲速率、全球海平面变化、和俯冲有关的动力沉降及俯冲负载等众多其它因素的影响。本文阐述了这些因素与前陆盆地沉降的关系,介绍了与幕式逆冲有关的地层模型和欠补偿-过补偿地层模型。希望本文能够对中国西北地区前陆盆地的研究起到一定的借鉴意义。

Subsidence mechanisms and stratigraphic models of foreland basins

Lithospheric flexure caused by orogenic loading is the main reason of the formation of foreland basins. The huge mass created by crustal thickening associated with thrusting of a mountain belt causes the regional isostatic subsidence beneath the orogenic load, generating a depression adjacent and parallel to the mountain belt. In addition, the evolution of a foreland basin is also influenced by many other factors, such as sediment supply, the efficiency with which sediment is distributed in the basin, strength of the lithosphere, thrust rate of the mountain belt, eustatic sea-level change and dynamic subsidence related to subduction. This paper describes the relationships between these factors and subsidence of foreland basins, and introduces stratigraphic models related to episodic thrusting and the underfilled-overfilled stratigraphic model. It is hoped that this paper can become a useful reference for stratigraphic studies in foreland basins in Northwest China.