Preprints
https://doi.org/10.5194/esurf-2022-64
https://doi.org/10.5194/esurf-2022-64
21 Dec 2022
 | 21 Dec 2022
Status: this preprint is currently under review for the journal ESurf.

Morphologic and Morphometric Differences between Gullies Formed in Different Substrates on Mars: New Insights into the Gully Formation Processes

Rishitosh Kumar Sinha, Dwijesh Ray, Tjalling De Haas, Susan J. Conway, and Axel Noblet

Abstract. Martian gullies are kilometer-scale geologically young features with a source alcove, transportation channel, and depositional fan. On the walls of impact craters, these gullies typically incise into bedrock or surfaces modified by latitude dependent mantle (LDM; inferred as consisting ice and admixed dust) and glaciation. To better understand the differences in alcoves and fans of gullies formed in different substrates and infer the flow types that led to their formation, we have analyzed the morphology and morphometry of 167 gully systems in 29 craters distributed between 30° S and 75° S. Specifically we measured length, width, gradient, area, relief, and relief ratio of alcove and fan, melton ratio, relative concavity index, and perimeter, form factor, elongation ratio and circularity ratio of the alcoves. Our study reveals that alcoves formed in LDM/glacial deposits are more elongated than the alcoves formed in bedrock, and possess a distinctive V-shaped cross section. We have found that mean gradient of fans formed by gullies sourced in bedrock is steeper than the mean gradient of fans of gullies sourced in LDM/glacial deposits. These differences between gullies were found to be statistically significant and discriminant analysis has confirmed that alcove perimeter, alcove relief and fan gradient are the most important variables for differentiating gullies according to their source substrates. The comparison between the melton ratio, alcove length and fan gradient of Martian and terrestrial gullies reveals that Martian gully systems were likely formed by terrestrial debris-flow like processes. It is likely that the present-day sublimation of CO2 ice on Mars provided the adequate flow fluidization for the formation of deposits akin to terrestrial debris-flow like deposits.

Rishitosh Kumar Sinha et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on esurf-2022-64', Anonymous Referee #1, 08 Feb 2023
    • AC1: 'Reply on RC1', RISHITOSH Sinha, 25 Apr 2023
  • RC2: 'Comment on esurf-2022-64', Anonymous Referee #2, 27 Mar 2023
    • AC2: 'Reply on RC2', RISHITOSH Sinha, 25 Apr 2023

Rishitosh Kumar Sinha et al.

Rishitosh Kumar Sinha et al.

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Short summary
Our detailed investigation of Martian gullies formed in different substrates in 29 craters distributed between 30°–75° S latitude suggests that they can be differentiated from one another in terms of (1) morphology and length of alcoves, and (2) mean gradient of the gully-fans. The comparison between the melton ratio, alcove length and fan gradient of Martian and terrestrial gullies suggest the Martian gullies were likely formed by terrestrial debris-flow like processes in the past.