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Impact-driven mobilization of deep crustal brines on dwarf planet Ceres
Nature Astronomy ( IF 12.9 ) Pub Date : 2020-08-10 , DOI: 10.1038/s41550-020-1168-2
C. A. Raymond , A. I. Ermakov , J. C. Castillo-Rogez , S. Marchi , B. C. Johnson , M. A. Hesse , J. E. C. Scully , D. L. Buczkowski , H. G. Sizemore , P. M. Schenk , A. Nathues , R. S. Park , T. H. Prettyman , L. C. Quick , J. T. Keane , M. D. Rayman , C. T. Russell

Ceres, the only dwarf planet in the inner Solar System, appears to be a relict ocean world. Data collected by NASA’s Dawn spacecraft provided evidence that global aqueous alteration within Ceres resulted in a chemically evolved body that remains volatile-rich1. Recent emplacement of bright deposits sourced from brines attests to Ceres being a persistently geologically active world2,3, but the surprising longevity of this activity at the 92-km Occator crater has yet to be explained. Here, we use new high-resolution Dawn gravity data to study the subsurface architecture of the region surrounding Occator crater, which hosts extensive young bright carbonate deposits (faculae). Gravity data and thermal modelling imply an extensive deep brine reservoir beneath Occator, which we argue could have been mobilized by the heating and deep fracturing associated with the Occator impact, leading to long-lived extrusion of brines and formation of the faculae. Moreover, we find that pre-existing tectonic cracks may provide pathways for deep brines to migrate within the crust, extending the regions affected by impacts and creating compositional heterogeneity. The long-lived hydrological system resulting from the impact might also occur for large impacts in icy moons, with implications for creation of transient habitable niches over time.



中文翻译:

矮行星谷神星上撞击驱动的深地壳盐水动员

谷神星(Ceres)是太阳系内部唯一的矮行星,似乎是一个残存的海洋世界。NASA的Dawn航天器收集的数据提供了证据,表明谷神星内部的全球水蚀改变导致了一种化学演化的物体,仍然富含挥发性物质1。最近从盐水中提取的明亮沉积物被放置,证明谷神星是一个持续地质活跃的世界2,3,但这项活动在92公里长的Occator火山口的惊人寿命还没有得到解释。在这里,我们使用新的高分辨率黎明重力数据来研究Occator火山口周围区域的地下构造,该火山口蕴藏着大量年轻的明亮碳酸盐矿床(岩藻类)。重力数据和热模拟表明Occator下方有一个深层盐水储层,我们认为这可能是由于与Occator撞击有关的加热和深层压裂而动员的,从而导致盐水的长期挤出和小孔的形成。此外,我们发现预先存在的构造裂缝可能为深层盐水在地壳内迁移提供路径,从而扩大受冲击影响的区域并造成成分异质性。

更新日期:2020-08-10
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