Effects of friction properties and rheological structures on the deformation patterns and evolution of fold-and-thrust belts-New insights from analogue modelling

Studying fold-and-thrust belts is crucial in geoscience; fold-and-thrust belts are rich in petroleum and natural gas. However, the effects of friction properties and rheological structures on the deformation patterns and evolution of fold-and-thrust belts with two detachment layers are less frequently discussed. Therefore, using models with a basal silicone layer, a middle silicone layer and overlying quartz sand layers, this study conducted an analogue modelling analysis of the effects of friction conditions, rheological structures and compressional velocity on the deformation and evolution of fold-and-thrust belts. The results show the following. 1) The weak layer or low friction strength of the basement forms complex deformations of the structural style, forming forward thrust, backward thrust, symmetrical pop-up structure and frontward-backward oscillating structural characteristics. 2) The friction strength ratio between the lateral and basement layers does not determine the structural style of a fold-and-thrust belt; moreover, it is closely related to the construction of strata or rheological structures. 3) The deformation of double detachment layers complicates the structural style of fold-and-thrust belts. 4) The analogue modelling results are similar to the structural style of the simple fold belt of the Zagros fold-and-thrust belt (ZFTB), indicating that deep and middle detachment layers control the current deformation of the ZFTB.

Automated summary

This study used analogue modelling to analyze the effects of friction conditions, rheological structures, and compressional velocity on the deformation and evolution of fold-and-thrust belts. The results showed that the weak layer or low friction strength of the basement formed complex structural deformations. The friction strength ratio between the lateral and basement layers did not determine the structural style of a fold-and-thrust belt; instead, it was closely related to the construction of strata or rheological structures. The deformation of double detachment layers complicated the structural style of fold-and-thrust belts. The analogue modelling results were similar to the structural style of the Zagros fold-and-thrust belt (ZFTB), suggesting that deep and middle detachment layers controlled the current deformation of the ZFTB.