Discussions on the tectonic attributes of the Mesozoic sedimentary basin in southern Micang Mountains

The southern part of the Micang Mountains north of the Sichuan Basin was previously considered as a foreland basin during the Late Triassic-Cretaceous.The authors argue,on the basis of tectonic and sedimentary evidences,that this area should be a down-warped basin rather than a foreland basin during the Late Triassic-Cretaceous,because:(1) the study area is an inherited uplift rather than a tectonic nappe,indicated by a large-scale incomplete anticline dome between the pre-Sinian basement and Sinian cover;(2) there was no regional stress contributing to the formation of the foreland basin.Furthermore,the study area was once subjected to the uplifting rather than the thrusting and compression from the Late Triassic onwards.The formation of the Micang Mountains should be limited in the Yanshanian when the large-scale overthrusting occurred,and(3) there was no sedimentary framework of a foreland basin in the form of a wedge during the Late Triassic-Cretaceous.