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Recent cryovolcanic activity at Occator crater on Ceres
Nature Astronomy ( IF 14.1 ) Pub Date : 2020-08-10 , DOI: 10.1038/s41550-020-1146-8
A. Nathues , N. Schmedemann , G. Thangjam , J. H. Pasckert , K. Mengel , J. Castillo-Rogez , E. A. Cloutis , H. Hiesinger , M. Hoffmann , L. Le Corre , J.-Y. Li , C. Pieters , C. A. Raymond , V. Reddy , O. Ruesch , D. A. Williams

NASA’s Dawn mission revealed a partially differentiated Ceres that has experienced cryovolcanic activity throughout its history up to the recent past. The Occator impact crater, which formed ~22 Myr ago, displays bright deposits (faculae) across its floor whose origins are still under debate: two competing hypotheses involve eruption of brines from the crust–mantle transition boundary (remnants of an ancient ocean) or alternatively from a shallow impact melt chamber. Here we report new constraints on the history of Occator that help in testing the hypotheses of its formation. We used high-resolution images of the Dawn Framing Camera obtained close to the end of the mission. We found a long-lasting and recent period of cryovolcanic activity, which started ≤9 Myr ago and lasted for several million years. Several resurfacing events, affecting the faculae and some (dark) solidified impact melt units, are shown to have occurred millions of years after crater formation and the dissipation of the impact-generated heat. These findings are indicative of a deep-seated brine source. Extensive volatile-driven emplacement of bright material occurred in the central floor, causing its subsidence due to mass loss at depth. Finally, a thick (extrusive) dome of bright material was raised in the central depression. The derived chronostratigraphy of Occator is consistent with a recently geologically active world, where salts play a major role in preserving liquid in a heat-starved body.



中文翻译:

在谷神星上Occator火山口的最新低温火山活动

美国国家航空航天局(NASA)的Dawn任务揭示了部分分化的谷神星,该谷神星在其整个历史直至最近的历史中都经历过冷冻维管活。形成于约22迈尔前的Occator撞击坑,在其整个地面上显示出明亮的沉积物(鳞屑),其起源尚有争议:两个相互竞争的假说涉及从地壳-幔幔过渡边界(古代海洋的残余物)喷出盐水或或者从一个浅冲击熔炼室。在这里,我们报告了Occator历史上的新限制条件,这些条件有助于检验其形成的假设。我们使用了接近任务结束时获得的黎明取景相机的高分辨率图像。我们发现了一个持续很长时间的冷冻卵泡活动,该活动始于≤9Myr并持续了几百万年。几次重铺事件,在火山口形成和撞击产生的热量消散后的数百万年中,已经发生了影响晶胞和某些(深色)凝固的撞击熔体单元的现象。这些发现表明存在深层的盐水源。在中层地板中,大量的挥发物驱动着明亮的材料发生位移,由于深处的质量损失,导致了它的沉降。最终,在中央凹陷处形成了一个明亮的材料厚(挤压)的圆顶。Occator的年代地层学与最近的地质活跃世界是一致的,在该世界中,盐在热不足的人体中保存液体方面起着主要作用。这些发现表明存在深层的盐水源。在中层地板中,大量的挥发物驱动着明亮的材料发生位移,由于深处的质量损失,导致了它的沉降。最终,在中央凹陷处形成了一个明亮的材料厚(挤压)的圆顶。Occator的年代地层学与最近的地质活跃世界是一致的,在该世界中,盐在热不足的人体中保存液体方面起着主要作用。这些发现表明存在深层的盐水源。在中层地板中,大量的挥发物驱动着明亮的材料发生位移,由于深处的质量损失,导致了它的沉降。最终,在中央凹陷处形成了一个明亮的材料厚(挤压)的圆顶。Occator的年代地层学与最近的地质活跃世界是一致的,在该世界中,盐在热不足的人体中保存液体方面起着主要作用。

更新日期:2020-08-10
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