Contractional strains and maximum displacement-length ratios of lunar wrinkle ridges in four Maria of basalt

Abstract

Compressional stresses from the basalt basins on the lunar are responsible for the formation of wrinkle ridges in lunar mare basalts. According to the wide angle multispectral camera (WAC) mosaic image, we selected 62, 75, 73, and 58 single wrinkle ridges in Mare Imbrium, Mare Serenitatis, Mare Fecunditatis, and Mare Tranquillitatis, respectively, for this paper. Several topographic profiles near the midpoint of each wrinkle ridge are generated to measure the maximum displacement ($D_{\max }$) and height of the wrinkle ridges using digital elevation model (LOLA) data. After that, we create 2D plots of displacement-length ($L$) for the ridge population in the four Maria and compare the results. A linear fit method derives the $D_{\max }/L$ ratios (γ) from the D-L data. We calculated the contractional strains in each mare area based on the cap D sub m a. x over cap L data. Moreover, each mare's gravity pattern, mare thickness, and formation age are also presented. The ridges in Mare Imbrium and Mare Serenitatis have a higher γ value (1.83 × 10⁻² and 1.98 × 10⁻²) than the ridges in Mare Fecunditatis and Mare Tranquillitatis, which have γ values of (1.67 × 10⁻² and 1.75 × 10⁻²). Finally, the contractional strains (ε) in Mare Imbrium, Mare Serenitatis, Mare Fecunditatis, and Mare Tranquillitatis are estimated to be 0.23 %, 0.41 %, 0.39 %, and 0.18 % (considering 25° is the fault plane dip θ), respectively. The maximum values of the free-air gravity anomalies in Mare Fecunditatis range from −30 to 250 mGal, while minimum gravity anomalies in Mare Serenitatis range from −80 to 140 mGal. Mare Imbrium, Mare Serenitatis, Mare Fecunditatis, and Mare Tranquillitatis have an average thickness of 300 m, 910 m, 652 m, and 760 m, respectively. Furthermore, the Mare Imbrium ridge group is older than the Lunar Wrinkle Ridges in Mare Serenitatis. Mare Tranquillitatis ridge group formation takes longer than Mare Imbrium ridge group formation. Therefore, we believe that it has thicker basaltic units, a longer wrinkle ridge formation time, and higher gravity anomaly than the Mare Imbrium and Mare Serenitatis basins, even though the formation of the Mare Tranquillitatis and Mare Fecunditatis basins occurred earlier.