DOI: 10.1002/2017JE005470
Scopus记录号: 2-s2.0-85041371904
论文题名: Distribution and Characteristics of Boulder Halos at High Latitudes on Mars: Ground Ice and Surface Processes Drive Surface Reworking
作者: Levy J.S. ; Fassett C.I. ; Rader L.X. ; King I.R. ; Chaffey P.M. ; Wagoner C.M. ; Hanlon A.E. ; Watters J.L. ; Kreslavsky M.A. ; Holt J.W. ; Russell A.T. ; Dyar M.D.
刊名: Journal of Geophysical Research: Planets
ISSN: 21699097
出版年: 2018
卷: 123, 期: 2 起始页码: 322
结束页码: 334
语种: 英语
英文关键词: climate
; crater
; impact
; Mars
; permafrost
; soil
Scopus关键词: climate variation
; crater
; emplacement
; ice
; image resolution
; Mars
; permafrost
; regolith
英文摘要: Boulder halos are circular arrangements of clasts present at Martian middle to high latitudes. Boulder halos are thought to result from impacts into a boulder-poor surficial unit that is rich in ground ice and/or sediments and that is underlain by a competent substrate. In this model, boulders are excavated by impacts and remain at the surface as the crater degrades. To determine the distribution of boulder halos and to evaluate mechanisms for their formation, we searched for boulder halos over 4,188 High Resolution Imaging Science Experiment images located between ~50–80° north and 50–80° south latitude. We evaluate geological and climatological parameters at halo sites. Boulder halos are about three times more common in the northern hemisphere than in the southern hemisphere (19% versus 6% of images) and have size-frequency distributions suggesting recent Amazonian formation (tens to hundreds of millions of years). In the north, boulder halo sites are characterized by abundant shallow subsurface ice and high thermal inertia. Spatial patterns of halo distribution indicate that excavation of boulders from beneath nonboulder-bearing substrates is necessary for the formation of boulder halos, but that alone is not sufficient. Rather, surface processes either promote boulder halo preservation in the north or destroy boulder halos in the south. Notably, boulder halos predate the most recent period of near-surface ice emplacement on Mars and persist at the surface atop mobile regolith. The lifetime of observed boulders at the Martian surface is greater than the lifetime of the craters that excavated them. Finally, larger minimum boulder halo sizes in the north indicate thicker icy soil layers on average throughout climate variations driven by spin/orbit changes during the last tens to hundreds of millions of years. ©2018. American Geophysical Union. All Rights Reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/114595
Appears in Collections: 气候减缓与适应
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作者单位: Department of Geology, Colgate University, Hamilton, NY, United States; Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States; NASA Marshall Space Flight Center, Huntsville, AL, United States; Department of Astronomy, Mount Holyoke College, South Hadley, MA, United States; Department of Engineering, Harvey Mudd College, Claremont, CA, United States; Earth and Planetary Sciences, University of California, Santa Cruz, CA, United States
Recommended Citation:
Levy J.S.,Fassett C.I.,Rader L.X.,et al. Distribution and Characteristics of Boulder Halos at High Latitudes on Mars: Ground Ice and Surface Processes Drive Surface Reworking[J]. Journal of Geophysical Research: Planets,2018-01-01,123(2)