Structural analysis of wrinkles ridges in the region between Aristarchus plateau and Marius Hills in Oceanus Procellarum (Moon).

Oceanus Procellarum (Ocean of Storms) represent the largest exposed mare basalts and it is located on the western lunar nearside. The study area of this work is located within this basin, between two big shield volcanoes: the Marius Hills complex and the Aristarchus plateau. The whole basin is affected by the presence of contractional landforms, known as wrinkle ridges, which are thrust-propagating folds with lengths range from tens to hundreds of kilometres. Since Oceanus Procellarum is a non-mascon (mass concentration) basin and, therefore, it is not associated to an excess of subsurface mass, the wrinkle ridges in the study area don’t follow a concentric distribution pattern and their strike is mainly in the N-S direction. 596 wrinkle ridges have been mapped with lengths ranging from 1324 m to 150 km, allowing to create a fracture intensity map with tiles size of 100 km * 100 km. A more detailed structural analysis has been carried out: (i) the Dmax/L has been investigated obtaining a γ value (scaling factor) of about 8.3E-3; (ii) the WRs have been classified by their vergence; (iii) five fault systems of WRs have been identified based on their spatial distribution and for each three parameters have been calculated: the average strike, the spacing, the original spacing; (iv) the décollement depths have been inferred applying the excess area method. About 75% of the calculated décollement depths ranges between 796 m and 2090 m, these horizons of weakness have been interpreted as paleo-regolith layers formed during hiatus in the volcanic activity of Oceanus Procellarum.