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David E Smith - One of the best experts on this subject based on the ideXlab platform.
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the age of lunar south circumpolar craters haworth shoemaker faustini and shackleton implications for Regional Geology surface processes and volatile sequestration
Icarus, 2015Co-Authors: Caleb I Fassett, A. T. Basilevsky, J W Head, A R Tye, David E SmithAbstract:Abstract The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size–frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D ⩾ 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D ⩾ 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slope-dependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have ∼1–2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have ∼5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (∼3.5 Ga) crater retention ages of their floors suggests that any water ice that might have been deposited in their permanently shadowed areas was insufficient to modify the superposed crater population since that time.
A R Tye - One of the best experts on this subject based on the ideXlab platform.
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the age of lunar south circumpolar craters haworth shoemaker faustini and shackleton implications for Regional Geology surface processes and volatile sequestration
Icarus, 2015Co-Authors: Caleb I Fassett, A. T. Basilevsky, J W Head, A R Tye, David E SmithAbstract:Abstract The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size–frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D ⩾ 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D ⩾ 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slope-dependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have ∼1–2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have ∼5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (∼3.5 Ga) crater retention ages of their floors suggests that any water ice that might have been deposited in their permanently shadowed areas was insufficient to modify the superposed crater population since that time.
A. T. Basilevsky - One of the best experts on this subject based on the ideXlab platform.
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the age of lunar south circumpolar craters haworth shoemaker faustini and shackleton implications for Regional Geology surface processes and volatile sequestration
Icarus, 2015Co-Authors: Caleb I Fassett, A. T. Basilevsky, J W Head, A R Tye, David E SmithAbstract:Abstract The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size–frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D ⩾ 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D ⩾ 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slope-dependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have ∼1–2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have ∼5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (∼3.5 Ga) crater retention ages of their floors suggests that any water ice that might have been deposited in their permanently shadowed areas was insufficient to modify the superposed crater population since that time.
Caleb I Fassett - One of the best experts on this subject based on the ideXlab platform.
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the age of lunar south circumpolar craters haworth shoemaker faustini and shackleton implications for Regional Geology surface processes and volatile sequestration
Icarus, 2015Co-Authors: Caleb I Fassett, A. T. Basilevsky, J W Head, A R Tye, David E SmithAbstract:Abstract The interiors of the lunar south circumpolar craters Haworth, Shoemaker, Faustini, and Shackleton contain permanently shadowed regions (PSRs) and have been interpreted to contain sequestered volatiles including water ice. Altimetry data from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter provide a new means of examining the permanently shadowed interiors of these craters in unprecedented detail. In this study, we used extremely high-resolution gridded LOLA data of Haworth, Shoemaker, Faustini, and Shackleton to determine the size–frequency distributions and the spatial density of craters superposing their rims, inner slopes, and floors. Based on their population of superposed D ⩾ 2 km craters, Haworth, Shoemaker, and Faustini have pre-Nectarian formation ages. Shackleton is interpreted as having a Late Imbrian age on the basis of craters with diameter D ⩾ 0.5 km superposed on its rim. The local density of craters with sub-km diameters across our study area is strongly dependent on slope; because of its steep interior slopes, the lifetime of craters on the interior of Shackleton is limited. The slope-dependence of the small crater population implies that the population in this size range is controlled primarily by the rate at which craters are destroyed. This is consistent with the hypothesis that crater removal and resurfacing is a result of slope-dependent processes such as diffusive mass wasting and seismic shaking, linked to micrometeorite and meteorite bombardment. Epithermal neutron flux data and UV albedo data show that these circumpolar PSRs, particularly Shoemaker, may have ∼1–2% water ice by mass in their highly porous surface regolith, and that Shoemaker may have ∼5% or more water ice by mass in the near subsurface. The ancient formation ages of Shoemaker, Faustini and Haworth, and the Late Imbrian (∼3.5 Ga) crater retention ages of their floors suggests that any water ice that might have been deposited in their permanently shadowed areas was insufficient to modify the superposed crater population since that time.
Dennis Brown - One of the best experts on this subject based on the ideXlab platform.
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Regional Geology extreme weather events and natural disasters environmentally forced involuntary settlement migrations of the indigenous people of southern taiwan
Tectonophysics, 2021Co-Authors: Slawomir Jack Giletycz, Olimpia Kotgiletycz, Dennis BrownAbstract:Abstract Active mountain belts in monsoonal climates are characterized by rapid denudation due to erosion and mass wasting processes. In such areas, unstable topography caused by local geological conditions combined with extreme rainfall or earthquakes impact on indigenous people, especially through involuntary settlement migration. Anthropological surveys in southern Taiwan show that the oral traditions of indigenous people preserve records of natural disasters that took place several hundred years ago. When combined with geological data, these stories allow us to assess the triggers and underlying causes that led to settlement migrations. These settlements are located in the Central Range of southern Taiwan, a high-relief terrain comprised of Miocene formations characterized by well-developed slaty cleavage (S1) that forms dip slopes that are prone to landslides. Here, we investigate how extreme events coupled with the geological setting caused two relocations of a settlement of the Paiwan group within approximately 350 years. We also draw attention to the point that the oral traditions of indigenous groups can provide important data sets for reconstructing landslides in the recent past (less than 500 years) which other, more traditional methods (e.g. digital data archives) do not record. We conclude that extreme weather provides the trigger, and local geological conditions the underlying factors, for natural disasters that have had a significant impact on the indigenous people in southern Taiwan.
