An Assessment of Regional Variations in Martian Modified Impact Crater Morphology. Issue 3 (23rd March 2018)

• Record Type: Journal Article
• Authors: Craddock, Robert A.; Bandeira, Lourenço; Howard, Alan D.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 3(2018)
• Page Start: 763
• Page End: 779
• Publication Date: 2018-03-23
• Subjects: crater modification -- rainfall -- climate evolution; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1002/2017JE005412
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: Impact craters on Mars have been extensively modified by ancient geologic processes that may have included rainfall and surface runoff, snow and ice, denudation by lava flows, burial by eolian material, or others. Many of these processes can leave distinct signatures on the morphometry of the modified impact crater as well as the surrounding landscape. To look for signs of potential regional differences in crater modification processes, we conducted an analysis of different morphometric parameters related to modified impact craters located in the Margaritifer Sinus, Sinus Sabaeus, Iapygia, Mare Tyrrhenum, Aeolis, and Eridania quadrangles, including depth, crater wall slope, crater floor slope, the curvature between the interior wall and the crater floor slope, and the curvature between the interior wall and surrounding landscape. A Welch's t test analysis comparing these parameters shows that fresh impact craters (Type 4) have consistent morphologies regardless of their geographic location examined in this study, which is not unexpected. Modified impact craters both in the initial (Type 3) and terminal stages (Type 1) of modification also have statistically consistent morphologies. This would suggest that the processes that operated in the late Noachian were globally ubiquitous, and that modified craters eventually reached a stable crater morphology. However, craters preserved in advanced (but not terminal) stages of modification (Type 2) have morphologies that vary across the quadrangles. It is possible that these variations reflect spatial differences in the types and intensity of geologic processes that operated during the Noachian, implying that the ancient climate also varied across regions. Plain Language Summary: Craters located in the ancient highlands were modified by geologic processes early in the history of Mars. While many analyses suggest that rainfall and surface runoff were involved, it is not clear if the intensity or duration of these processes changed from region to region or over time. Here we present a morphologic analyses of modified craters located in different regions. Statistical analyses show where the craters were different, which has implications for understanding the past climate and history of water on Mars. Key Points: Modified craters on Mars show temporal and spatial variations This implies regional variations in the types and intensity of geologic process that operated during the early Noachian Craters preserved in advanced (but not terminal) stages of modification (Type 2) have morphologies that vary across the quadrangles