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Floor Materials of Open Paleolake Basins on Mars
| Content Provider | Semantic Scholar |
|---|---|
| Author | Irwin, Rossman P. Maxwell, Terrence A. Howard, Alan D. Higbie, M. A. |
| Copyright Year | 2009 |
| Abstract | Introduction: Many previous regionalto globalscale studies have identified features that may be attributable to paleolakes on early Mars [e.g., 1–8]. The most suggestive landforms include outlet valleys from basins with undissected floors [e.g., 6] (leaving a residual basin on the crater floor); positive-relief deposits with a frontal scarp at the end of contributing valleys [e.g., 5]; and thinly layered, spectrally distinct products of aqueous weathering that are confined to basin floors [e.g., 7]. Other potentially relevant features include terraces that partially or wholly surround a basin [e.g., 8] and etched terrains within basins [2]. An important issue is the extent to which volcanic flows have resurfaced Martain paleolake basins [1,6,9,10]. Resolution of this question on a case-bycase basis will enable better targeting of orbital and landed assets, and the global perspective will be useful in determining the extent of basaltic volcanism on Mars after the Noachian/Hesperian transition. Fassett and Head [6] published a catalog of basins with both contributing and outlet valleys (termed “open basins”) in the Martian equatorial highlands, as these features are the most common and compelling indicators of paleolakes. They found that in most cases, open basins have smooth floors or secondary wrinkle ridges and a well-preserved population of small impact craters, suggesting a resistant material that post-dates the contributing fluvial networks. A smaller fraction of the open-basin floors has knobby or etched surfaces. Here we examine spatial relationships between outlet valleys and basin floor morphology, two key elements that may indicate paleolakes, to evaluate whether late volcanic resurfacing of basin floors was a widespread occurrence on Mars, or if the efficacy of recent aeolian erosion was variable across the surface, accounting for morphological differences in floor materials of broadly similar composition. Methods: In a study area between 0–30°S, 120– 165°E, we examined the spatial relationships between open basins and wind-eroded crater floors (both open and closed basins), which likely contain less-resistant sedimentary deposits at the surface. The open-basin dataset provided by Caleb Fassett was used with Thermal Emission Imaging System (THEMIS) visible (VIS) and day/night infrared (DIR/NIR) imaging, as well as high-resolution imaging from the Mars Orbiter Camera (MOC), Context Camera (CTX), and HighResolution Imaging Science Experiment (HiRISE). Not all Noachian craters have imaging at suitable (<20 m/pixel) resolution to detect the etching patterns described here, but the spatial relationships are relatively clear (Fig. 1) even without complete coverage. Observations: In this eastern-hemisphere study area, the open-basin paleolakes are concentrated along northward-sloping terrain along the crustal dichotomy boundary (Fig. 1). This region is also prevalently dust-covered. However, the low-albedo area immediately to the south has a large concentration of degraded impact craters with heavily etched floors (e.g., Fig. 2), in contrast to the smooth or ridged plains that prevail within Noachian craters in dusty, light-toned areas to the north. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2358.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
