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The Nature of the Transition from Lobate Debris Aprons to Lineated Valley Fill: Mamers Valles, Northern Arabia Terra-Deuteronilus Mensae Region on Mars
| Content Provider | Semantic Scholar |
|---|---|
| Author | Kress, Anne M. Head, James W. Marchant, David R. |
| Copyright Year | 2006 |
| Abstract | Introduction: Lineated valley fill (LVF) and lobate debris aprons (LDA) form in association with fretted terrain and fretted channels in the northern part of Arabia Terra [1-3]. Geological mapping in the region [4] shows that LVF and LDAs represent Amazonian-aged modification of the fretted topography, which itself formed prior to middle Hesperian. Analysis of MOLA data [5] revealed slope reversals in Mamers Valles, a Hesperian fretted valley , suggesting that down-valley flow of lineated terrain was minor; assessment of MOC and MOLA together revealed a three-component slope-texture typical of many LDAs: 1) steep 20-30° upper bedrock slope, 2) intermediate 3-5° slope with smooth texture or lineations normal to the slope, 3) main LDA sloping 1-3°, extending up to 20 km, with a distal margin sloping up to 6° [5]; LDAs were interpreted [5] as debris flows lubricated by ground ice in the material undergoing mass wasting. Among the many uncertainties associated with an understanding of the LDA and LVF are: 1) the direction of flow in LDA and LVF (either normal to the valley [2], or parallel, down-valley [6]); 2) the extent and continuity of flow in LVF [5]; 3) relationships between the LDA and the LVF; and 4) the mode of origin of the LDA and LVF (e.g., groundwater-fed, ice-assisted rock creep, ice-rich landslides , rock glaciers, debris-covered glaciers) [2-7]. Recent analyses of LVF in adjacent regions [8-9] have shown evidence for local sources of LVF in alcoves in valley walls, down-valley flow, merging of flowlines into broad trunk valleys, extensive along-valley flow, and termination in lobate deposits, all features that are similar to valley glacial landsystems on Earth. In this study we analyzed LDAs, LVF, and their relationships along >900 km 2 of the length of Mamers Valles from the crater Cerulli north to the area just south of Deuteronilus Colles (Fig. 1), and also assessed its distribution in along-valley and intersecting craters (Fig. 1). We subdivided LDAs into linear (occurring along valley walls and crater interiors) and circumfer-ential (aprons generally surrounding isolated massifs). General characteristics and distribution of LDA and LVF: Mamers Valles can be subdivided into its lower reaches, where it averages <10 km in width, and its upper reaches where it is 20-30 km in width (Fig. 1). Most of the valley walls of the upper reaches are characterized by linear LDAs; high-resolution images show that LDAs are composed of dozens of parallel lobes that … |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://people.bu.edu/marchant/_assets/_documents/dave_conference%20abstracts/LPS%20Abstracts/Kress_LPSC_2006_1323.pdf |
| Alternate Webpage(s) | http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1323.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
