Geochronology, petrogenesis and geological significance of the lunar basalts around CE-3 landing site

Lunar basalts are mainly located in the Maria, and made up of anorthosite, pyroxene and olivine. Different from basalts in Earth, they are rich in Fe and depleted in Na and K. The origin, ages and compositions of the lunar basalts are the basis of understanding the formation and evolution of lunar rocks. The rock samples returned from the Moon have limited numbers and don' t cover the CE-3 landing site, thus, the methods of analyzing the rocks in ground labs cannot be used to study lunar basalts. In this paper, our researches focused on the compositions, origin, distribution, age and sequence of basalts in and under lunar surface around CE-3 landing site. The methods we used in this paper included: crater size-frequency distribution, the underlying basalts identification, the compositions derived from the remote sensing data, and so on. The results showed that: (1) There are at least six basaltic filling processes in study area and we can define six basaltic units from young to old which are EIm, EIm Elm,, Im, Im, and Tin,. The age of EIm is 3. 17Ga, while Im' s age is 3. 48Ga. (2) Around CE-3 landing site, titanium content changes a lot, while iron content shows a few changes. There is a link between identified basalts' age and their element abundance, which is the younger the age, the more enrichment in titanium and iron. In addition, there is no evidence for high silica materials according to the CF factor and CI index derived from thermal infrared data. (3) The study area has experienced multiple magmatic events, and every fill process flows from south to north and its magnitude reduces gradually. (4) The average thicknesses of five underlying basalts (EIm EIm2, Im, Im, and Im(2)) are 68. 3m, 68. 6m, 81. 8m, 59. lm and 52. lm separately, and the most thicknesses of EIm, and 1m1 are 150m and 224m.