کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1780988 | 1523928 | 2015 | 17 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Formation and mantling ages of lobate debris aprons on Mars: Insights from categorized crater counts
ترجمه فارسی عنوان
سن سازندگی و انحطاط پیشانی های بریده بر روی مریخ: بینش از تعداد دهانه دسته بندی شده
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
چکیده انگلیسی
Lobate debris aprons in the Martian mid-latitudes offer important insights into the history of the Martian climate and the role of volatiles in Martian geologic activity. Here we present the results of counts of small impact craters, categorized by morphology, on debris aprons in the Deuteronilus Mensae region and the area east of Hellas basin. Mars Reconnaissance Orbiter (MRO) ConTeXt Camera (CTX) images were used to document crater populations on the apron surfaces. Each crater was assessed and categorized according to its morphological characteristics (fresh, degraded, or filled). Fresh and most degraded craters likely superpose recent mantling deposits, whereas filled craters contain mantling deposits and thus indicate a minimum formation age for the apron (i.e., the age since stabilization of the debris apron surface following some modification but prior to mantling). Size-frequency distributions (SFDs) were compiled using established methodologies and plotted to assess their fit to the isochrons. The range or ranges in crater diameter over which each distribution paralleled the isochrons was determined by visual inspection, and general age constraints were noted from SFDs for all craters on a given surface and from each morphological class. The diameter range of each SFD segment observed to parallel an isochron was then input into the Craterstats2 analysis tool to calculate specific age estimates. The aprons were assessed both individually and as regional populations, which improved interpretation of the results and demonstrated the value and limitations of both approaches. The categorized counts reveal three groups of ages: (a) filled impact craters at larger diameters (>~500Â m) typically show the oldest ages, between ~300Â Ma and 1Â Ga, (b) smaller diameter filled and degraded craters reveal ages of resurfacing events between ~10Â Ma and 300Â Ma, and (c) fresh crater populations (<~100Â m diameter) indicate mantling deposits of less than ~10Â Ma in age. These results indicate that the lobate debris apron populations formed (or their surfaces became stable) in the Early to Middle Amazonian Epochs, and were subsequently subjected to complex degradation by erosion and sublimation and/or melting of contained ice, culminating in episodes of deposition of ice-rich mantles in the Late Amazonian Epoch.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Planetary and Space Science - Volume 111, June 2015, Pages 83-99
Journal: Planetary and Space Science - Volume 111, June 2015, Pages 83-99
نویسندگان
Daniel C. Berman, David A. Crown, Emily C.S. Joseph,