Compositional diapirism as the origin of the low albedo terrain and vaporization at mid-latitude on Ceres
Compositional diapirism as the origin of the low albedo terrain and vaporization at mid-latitude on Ceres
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构成底辟作用是谷神星中纬度低反照率地形和蒸发的起源
DOI：
10.1002/2014je004695
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
K. Kurita
中科院分区：
文献类型：
--
作者：
D. Shoji;K. Kurita
最近使用欧洲航天局赫歇尔空间天文台上的远红外外差仪器对谷神星进行的观测表明，水蒸气是从低反照率中纬度地区散发出来的。基于木卫二上的一些黑斑可能是底辟作用造成的假设，我们探讨了谷神星的环境是否也能诱发成分底辟作用，以及上升的底辟是否可以解释黑斑的起源和分布以及谷神星的蒸发。如果构成谷神星的岩石的密度约为 2700 kg m−3，则未分化的地壳在地质时期内稳定在低于 180 K 的温度。在 170 K 的表面温度下，如果地壳有几十公里厚，底辟就可以到达地表。或者，如果表面温度为 150 K，粘度的大差异将阻止底辟到达表面。谷神星中纬度地区相对温和的表面温度可能是仅在这些地区形成黑暗地形的原因。我们的有限差分计算并未表明底辟作用会融化表面冰，因为温度梯度变化很小。然而，如果观察到的蒸汽排放是由新鲜冰的升华引起的，则成分底辟作用可能是将新鲜冰输送到表面的机制。除了低温火山作用等其他机制之外，底辟作用也是解释谷神星黑暗地形和蒸气排放的有效假设。
Recent observations of Ceres, made using the Heterodyne Instrument for the Far Infrared on board the European Space Agency's Herschel Space Observatory, have shown that water vapor is emanated from the low‐albedo midlatitude regions. Based on the supposition that some dark spots on Europa may be caused by diapirism, we explored whether Ceres' environment also can induce compositional diapirism, and whether an upwelling diapir could explain the origin and distribution of the dark spots and vaporization of Ceres. If the density of the rock that constitutes Ceres is around 2700 kg m−3, the undifferentiated crust is stable over geological time periods at less than 180 K. At a surface temperature of 170 K, a diapir can reach the surface if the crust is a few tens of kilometers thick. Alternatively, if the surface temperature is 150 K, a large contrast in viscosity would prevent diapirs from reaching the surface. The relatively moderate surface temperature in the midlatitude regions of Ceres may be the reason for the formation of dark terrains occurring only in such areas. Our finite difference calculations do not show that diapirism melts the surface ice because the temperature gradient changes very little. However, if the observed vapor emission is caused by the sublimation of fresh ice, compositional diapirism could be the mechanism that transports the fresh ice to the surface. In addition to other mechanisms such as cryovolcanism, diapirism is a valid hypothesis for explaining the dark terrain and vapor emissions of Ceres.