The occurrence of Middle Triassic extensional and strike-slip tectonics has been widely recognized in the Dolomites and is supported by stratigraphic evidence. Contrarily, the recognition of Triassic contractional tectonic structures is less straightforward because such structures were heavily superimposed by Neogene Alpine shortening.

In this work we provide a detailed analysis of a top-class outcrop displaying a syn-sedimentary Middle Triassic extensional fault that displaces a coeval sedimentary mélange containing an olistholith of Lower Triassic rocks, characterized by Triassic contractional structures (folds, axial plane cleavage, joints, local thrust faults ornamented with slickenfibers and associated with forced folds).

In particular, integrating geological field mapping and structural analyses, structural analyses on a 3D virtual outcrop model and microstructural analyses, we demonstrate that: 1) the orientation of tectonic structures in the olistholith is at odd with that of regional structures, implying that deformation occurred prior to deposition of the melange; 2) folds and small-scale thrusts in the olistholith developed in lithified rocks, pointing to the existence of Middle Triassic fold and thrust tectonics. In summary, the tectonic structures in the analyzed olistholith represent an outstanding, possibly unique, example of fully preserved, practically frozen, Middle Triassic contractional structures.

中三叠统伸展和走滑构造的发生在白云岩中得到了广泛认可，并得到地层证据的支持。相反，三叠纪收缩构造结构的识别则不那么简单，因为这些结构被新近纪高山缩短作用严重叠加。

在这项工作中，我们提供了一个顶级露头的详细分析，该露头显示了一个同沉积的中三叠统伸展断层，该断层取代了包含下三叠统岩石块石的同时代沉积混杂岩，其特征在于三叠纪收缩结构（褶皱、轴向平面解理、节理，局部逆冲断层饰有光滑纤维并伴有强迫褶皱）。

特别是，结合地质场填图和构造分析、3D虚拟露头模型的构造分析和微观结构分析，我们证明：1）石方石中的构造构造方向与区域构造方向不一致，暗示发生了变形。在混合物沉积之前；2) 石化岩石中发育包石中的褶皱和小规模逆冲，表明存在中三叠世褶皱逆冲构造。总之，所分析的石方岩中的构造结构代表了一个杰出的、可能是独特的、完全保存的、几乎冻结的中三叠世收缩结构的例子。