Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.1002/2017GL073334 |
Isostatic equilibrium in spherical coordinates and implications for crustal thickness on the Moon, Mars, Enceladus, and elsewhere | |
Hemingway, Douglas J.1; Matsuyama, Isamu2 | |
2017-08-16 | |
发表期刊 | GEOPHYSICAL RESEARCH LETTERS
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ISSN | 0094-8276 |
EISSN | 1944-8007 |
出版年 | 2017 |
卷号 | 44期号:15 |
文章类型 | Article |
语种 | 英语 |
国家 | USA |
英文摘要 | Isostatic equilibrium is commonly defined as the state achieved when there are no lateral gradients in hydrostatic pressure, and thus no lateral flow, at depth within the lower viscosity mantle that underlies a planetary body's outer crust. In a constant-gravity Cartesian framework, this definition is equivalent to the requirement that columns of equal width contain equal masses. Here we show, however, that this equivalence breaks down when the spherical geometry of the problem is taken into account. Imposing the "equal masses" requirement in a spherical geometry, as is commonly done in the literature, leads to significant lateral pressure gradients along internal equipotential surfaces and thus corresponds to a state of disequilibrium. Compared with the "equal pressures" model we present here, the equal masses model always overestimates the compensation depth-by similar to 27% in the case of the lunar highlands and by nearly a factor of 2 in the case of Enceladus. Plain Language Summary "Isostasy" is the principle that, just as an iceberg floats on the water, crustal rocks effectively float on the underlying higher density mantle, which behaves essentially like a fluid on geologic timescales. Although there are subtle inconsistencies among the various ways isostasy can be defined, they have not been historically problematic for bodies like the Earth, where the crust is thin compared with the overall radius. When the thickness of the crust is a nonnegligible fraction of a planetary body's radius, however, it becomes important to take the spherical geometry into account. In this case, the inconsistencies in the definitions can lead to significant discrepancies. Here we argue that one of the most commonly used approaches, which requires equal width columns to contain equal masses, always results in overestimating the crustal thickness. In particular, we suggest that the lunar and Martian highlands crustal thickness may have been overestimated by similar to 27% and similar to 10%, respectively, and that the ice shell thickness for Saturn's small icy moon Enceladus may have been overestimated by nearly a factor of 2. |
领域 | 气候变化 |
收录类别 | SCI-E |
WOS记录号 | WOS:000408379000016 |
WOS关键词 | GEOID ANOMALIES ; ICE SHELL ; CASSINI GRAVITY ; COMPENSATION ; PLANETS ; RELAXATION ; TOPOGRAPHY ; SUPPORT ; PLATE ; FIELD |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/25614 |
专题 | 气候变化 |
作者单位 | 1.Univ Calif Berkeley, Dept Earth & Planetary Sci, Berkeley, CA 94720 USA; 2.Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA |
推荐引用方式 GB/T 7714 | Hemingway, Douglas J.,Matsuyama, Isamu. Isostatic equilibrium in spherical coordinates and implications for crustal thickness on the Moon, Mars, Enceladus, and elsewhere[J]. GEOPHYSICAL RESEARCH LETTERS,2017,44(15). |
APA | Hemingway, Douglas J.,&Matsuyama, Isamu.(2017).Isostatic equilibrium in spherical coordinates and implications for crustal thickness on the Moon, Mars, Enceladus, and elsewhere.GEOPHYSICAL RESEARCH LETTERS,44(15). |
MLA | Hemingway, Douglas J.,et al."Isostatic equilibrium in spherical coordinates and implications for crustal thickness on the Moon, Mars, Enceladus, and elsewhere".GEOPHYSICAL RESEARCH LETTERS 44.15(2017). |
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