Powering prolonged hydrothermal activity inside Enceladus
Powering prolonged hydrothermal activity inside Enceladus
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DOI：
10.1038/s41550-017-0289-8
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发表时间：
2017-12-01
期刊：
影响因子：
14.1
通讯作者：
Soucek, Ondrej
中科院分区：
文献类型：
--
作者：
Choblet, Gael;Tobie, Gabriel;Soucek, Ondrej
卡西尼号航天器的地球物理数据表明，土卫二冰壳下方存在全球海洋(1)，距离南极地形地表仅几公里(2-4)。化学分析表明海洋是咸的(5)，并且由持续的热液活动供给营养(6-8)。为了解释这些观察结果，需要异常高的热功率（>200 亿瓦），以及将内生活动集中在南极的机制(9,10)。在这里，我们表明松散岩石核心内部的潮汐摩擦可以产生超过 10 GW 的热量。潮汐加热的可渗透核心中的水输送导致温度超过 363 K 的狭窄热上升流，其特点是海底（特别是南极）存在强大的（1-5 GW）热点。狭窄区域的热量释放有利于水和岩石之间的强烈相互作用，以及热液产物从核心到羽流源的输送。因此，我们能够解释土卫二的主要全球特征：全球海洋、强耗散、南极冰壳厚度减少和海底活动。我们预测这种内源性活动可以持续数千万至数十亿年。
Geophysical data from the Cassini spacecraft imply the presence of a global ocean underneath the ice shell of Enceladus(1), only a few kilometres below the surface in the South Polar Terrain(2-4). Chemical analyses indicate that the ocean is salty(5) and is fed by ongoing hydrothermal activity(6-8). In order to explain these observations, an abnormally high heat power (>20 billion watts) is required, as well as a mechanism to focus endogenic activity at the south pole(9,10). Here, we show that more than 10 GW of heat can be generated by tidal friction inside the unconsolidated rocky core. Water transport in the tidally heated permeable core results in hot narrow upwellings with temperatures exceeding 363 K, characterized by powerful (1-5 GW) hotspots at the seafloor, particularly at the south pole. The release of heat in narrow regions favours intense interaction between water and rock, and the transport of hydrothermal products from the core to the plume sources. We are thus able to explain the main global characteristics of Enceladus: global ocean, strong dissipation, reduced ice-shell thickness at the south pole and seafloor activity. We predict that this endogenic activity can be sustained for tens of millions to billions of years.