Enigmatic Features of a Crater in Arabia Terra, Mars

Content Provider	Semantic Scholar
Author	Lahtela, H. M. Korteniemi, Jarmo Pondrelli, Monica Lorenzo, S. Conforti Di Neukum, Gerhard
Copyright Year	2006
Abstract	Introduction: This study discusses the characteristics of an enigmatic ~25 km crater (Fig. 1a), located at 36,0Nº/351,8Eº, in Arabia Terra; highland side of the dichotomy boundary. It has roughly circular shape and exhibits almost no raised rim. From HRSC, THEMIS, MOC and MOLA data, four distinct terrain units are identified: 1) smooth floor, 2) unit cracked by severe fissuring, 3) low albedo depression and 4) prominent central bulges (Fig. 1b). All units tell of intense crater floor deformation. This structure differs drastically from a standard impact crater. It is an interesting study subject, providing detailed info with which similar features in the region can be re-evaluated. Structure description: The crater is mapped to be of Noachian age [1]. It is ~700 m deep, and has no apparent rim or traceable ejecta field. The crater is located on a shallow 0.3° regional NE trending slope. The crater walls exhibit layering. However, only one layer is observed to be continuous around the crater (except in E), at a level depth of-3.6-3.7 km MPR. It is darker than the under-and overlying layers, and is the source of numerous gullies (Fig. 1d). Layer-ing is observed in several but not all craters in the region. Two channels (mouth width <1 km) cut trough the wall, but there is no sign of delta formation or clear terraces within the crater. Flat material occupies the W and S crater floor, resembling 'normal looking' crater fill, i.e. sedimentary materials accumulated and partly eroded after crater formation. On the floor at the foot of crater walls there are indications of mass wasting deposits. Fractured terrain is observed when closer to crater center. The western part of this unit has chaotic appearance. Fracture walls exhibit horizontal layers (Fig. 1c). The unit slopes down to an 11 km diameter and 50 m deep smooth-floored depression at the crater center. Bulges. The central depression has two separate prominent bulges. The western one is clearly more massive (height H=300 m, volume V=6 km 3 ; Fig 1 " 1 ") than the eastern one (H=70 m, V=0.04 km 3 ; Fig 1 " 2 "). Even though the bulges lie in the depression, they clearly reach higher than the main crater floor. They are significantly offset from the crater center (large 4.2 km, small 7.5 km). Both bulges have similar shapes: narrow E-W ridge traverses along their S edge, creating a N-S asymmetry …
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Alternate Webpage(s)	http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2114.pdf
Alternate Webpage(s)	https://www.lpi.usra.edu/meetings/lpsc2006/pdf/2114.pdf
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article