Tectonic evolution of northwestern Imbrium of the Moon that lasted in the Copernican Period

Abstract

The formation ages of tectonic structures and their spatial distributions were studied in the northwestern Imbrium and Sinus Iridum regions using images obtained by Terrain Camera and Multiband Imager on board the SELENE spacecraft and the images obtained by Narrow Angle Camera on board LRO. The formation ages of mare ridges are constrained by the depositional ages of mare basalts, which are either deformed or dammed by the ridges. For this purpose, we defined stratigraphic units and determined their depositional ages by crater counting. The degradation levels of craters dislocated by tectonic structures were also used to determine the youngest limits of the ages of the tectonic activities. As a result, it was found that the contractions to form mare ridges lasted long after the deposition of the majority of the mare basalts. There are mare ridges that were tectonically active even in the Copernican Period. Those young structures are inconsistent with the mascon tectonics hypothesis, which attributes tectonic deformations to the subsidence of voluminous basaltic fills. The global cooling or the cooling of the Procellarum KREEP Terrane region seems to be responsible for them. In addition, we found a graben that was active after the Eratosthenian Period. It suggests that the global or regional cooling has a stress level low enough to allow the local extensional tectonics.

Timing and Origin of Compressional Tectonism in Mare Tranquillitatis

“…However, as previously stated, Mare Tranquillitatis is of irregular shape, which could influence subsidence‐induced stress patterns, and the role of the thickness of the elastic lithosphere in the wrinkle ridge formation is also a factor (Watters, 2022). Previous studies have discussed the prolonged cooling, triggered by the abundance of heat‐producing elements, of the Procellarum KREEP Terrane (PKT) to be a factor in the recent wrinkle ridge formation (Daket et al., 2016; Lu et al., 2019). However, Mare Tranquillitatis is not associated with the PKT (Wieczorek & Phillips, 2000).…”

The Geological History of the Chang’e-5 Sample Return Region

“…According to the approach proposed by Moore et al [51], if the ages of distorted craters are determined, the formation of wrinkle ridges that distorted these craters must postdate the formation of these craters [51]. Williams et al [52] and Daket et al [53] have used a similar approach to determine the ages of wrinkle ridges and lobated scraps [52,53] in Mare Frigoris and Mare Imbrium. Thus, we used this approach to determine the wrinkle ridges in the U7/Em5 unit (Figure S1 and S2) where the CE-5 sample return mission landed.…”

Datação diferenciada das planícies vulcânicas lunares através da densidade espacial de crateras de impacto

“…A identificação das fronteiras destas unidades tem sido essencialmente efetuada através de abordagens qualitativas de interpretação geológica em imagens remotas obtidas pelas várias missões espaciais, mas principalmente Clementine e Chandrayaan-1 por terem sensores capazes de obter dados multiespectrais da superfície da Lua. A contagem [5][6][7][8][9]. No entanto, devido à utilização diferenciada de dados em cada estudo e, sobretudo, devido às diferentes interpretações geológicas, os mapas propostos apresentam claras diferenças entre si, não só no número de unidades detetadas, mas também na localização das respetivas fronteiras (Figura 1b).…”