Gravity field of the Orientale basin from the Gravity Recovery and Interior Laboratory Mission

Abstract

The Orientale basin is the youngest and best-preserved major impact structure on the Moon. We used the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft to investigate the gravitational field of Orientale at 3-5-km horizontal resolution. A volume of at least (3.4±0.2)x10 6 km 3 of crustal material was removed and redistributed during basin

Ring faults and ring dikes around the Orientale basin on the Moon

“…Although the interpretation of a 50° Outer Rook fault dip in Zuber et al (2016) is at odds with the vertical fault in some parts of the basin supported by this analysis of the gravity gradients and crustal structure, the profiles of the crust-mantle interface in that study also show an inflection immediately beneath the Outer Rook south of the basin that could be interpreted as the signature of a vertical fault. Nevertheless, we note that the dips from Zuber et al (2016) Rook and gentler dips for the Cordillera than that study, both studies agree that the Outer Rook fault dips more steeply than the Cordillera fault.…”

“…Thus, the location of the positive gravity gradient anomaly in this pair provides the best measurement of the radius of the excavated crustal cavity of ~190 km (c.f., Johnson et al, 2016). However, as previously noted by Zuber et al (2016), this radius is less than the 232-km radius of the Inner Rook ring. This offset between the expression of the edge of the excavated crustal cavity seen at the crust-mantle interface and the edge of the central topographic cavity at the Inner Rook is also seen in the crustal thickness models, but at lower resolution than can be obtained with the gravity gradients (see Section 3.2).…”

“…Other studies have used azimuthal averaging to attempt to resolve ring structures (Andrews-Hanna, 2013;Kattoum and Andrews-Hanna, 2013;Zuber et al, 2016), but were not able to resolve the subsurface structure of the rings in map view or the variations in their properties with azimuth.…”

“…In Bouguer gravity data (Fig. 1c), the basin is characterized by a strong positive central anomaly marking the uplifted mantle plug (Neumann et al, 2015b(Neumann et al, , 1996Wieczorek and Phillips, 1999;Zuber et al, 2016), surrounded by a negative annulus (Andrews-Hanna, 2013;Wieczorek and Phillips, 1999;Zuber et al, 1994) …”

“…Alternatively, the inner ring might be an analog of structures in the Crisium basin, which are interpreted as the surface expression of thrust faults bounding the uplifted mantle beneath the basin center (Byrne et al, 2015). The inner depression approximately corresponds with the central positive Bouguer anomaly (Neumann et al, 2015b;Zuber et al, 2016), centered at °N °E, r ~ km. The basin center has been partially resurfaced by Mare Orientale, a low albedo thin volcanic deposit formed after the basin (Fig.…”