The Gardner volcanic complex on the Moon: Geological characteristics and its volcanic history

Abstract

Lunar volcanic complexes are prominent features with a high concentration of various volcanic characteristics. They are ideal objects to study the lunar nearside volcanic activity and its thermal evolution. The Gardner volcanic complex is located in the nearside of the Moon, between Mare Serenitatis and Mare Tranquillitatis. It has a series of volcanic features, such as domes and rilles, which make it an ideal object to study the lunar volcanic history. In this study, we make use of recent high-resolution lunar images (Terrain Camera, TC) and multispectral data (Clementine UVVIS) to study the topography, geomorphologic features, iron and titanium contents, and the geochronology of the Gardner volcanic complex. We identified and analyzed different geomorphologic features, such as impact craters, domes, massifs, scarps, and a suspected fault. Spectral analyses indicated that the Gardner region is covered by low-Ti basalt. Absolute model ages of the different units in the Gardner region were obtained using crater size-frequency distribution (CSFD) measurement. The results show that Gardner may have experienced three periods of volcanic activities, which were aged between Nectarian and Imbrium. The volcanic eruption may decrease with time. The relatively high crustal density and the positive Bouguer gravity anomaly of Gardner show that the Gardner volcanic complex is composed of dense volcanic materials on the surface and in the subsurface. An irregular steep-sided depression is located in the central area of the Gardner plateau, which is different from the depression caused by impacting. We suggest that this depression could be a caldera and is once a possible vent responsible for the emplacement of surrounding lava flows. The long history of volcanic activities in this region makes it an ideal area to study the lunar nearside volcanism and thermal evolution, and we suggest it as a candidate landing site for China’s future lunar exploration missions.