Caloris impact basin: Exterior geomorphology, stratigraphy, morphometry, radial sculpture, and smooth plains deposits
Caloris impact basin: Exterior geomorphology, stratigraphy, morphometry, radial sculpture, and smooth plains deposits
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DOI：
10.1016/j.epsl.2009.05.022
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发表时间：
2009-08-15
影响因子：
5.3
通讯作者：
Watters, Thomas R.
中科院分区：
文献类型：
--
作者：
Fassett, Caleb I.;Head, James W.;Watters, Thomas R.
水手10号的飞越揭示了Caloris盆地东部的三分之一，并证明了它作为水星地质历史年代地层标志的重要性。在那次使命之后，不确定的是盆地的大小，在撞击过程中沉积或改变的物质的全部分布，以及卡路里和周围地形之间的地层和年龄关系。在信使号2008年1月飞越水星期间获得的图像显示，卡路里盆地比先前估计的大15%，并且是中等椭圆形的（与1525年相似，与1315公里相似）。与盆地有关的雕塑和次级火山口广泛分布在盆地周围地区，证实了这一事件作为地层标志的广泛意义。根据水手10号数据绘制的Caloris周围的单元在信使号首次观察到的区域中得到了普遍认可，包括Caloris群的大多数相（Caloris Montes，Odin Formation和货车Eyck Formation）。信使号图像中唯一没有明显暴露的单位是Nervo地层，最初被解释为撞击熔融物或回落喷出物。新的测量结果的大小和频率分布的影响陨石坑内的Caloris盆地和周围的单位，特别是奥丁组，支持的假设，绝大多数环Caloris平原晚于盆地，可能是火山。信使号的观测再次强调了了解盆地外部地层的重要性，以便利用Caloris事件作为水星地质历史中的离散时间范围。(C)2009爱思唯尔有限公司版权所有。
The Mariner 10 flybys revealed the eastern third of the Caloris basin and demonstrated its importance as a chronostratigraphic marker for the geological history of Mercury. Uncertain after that mission were the size of the basin, the full distribution of materials deposited or modified during the impact process, and the stratigraphic and age relationships between Caloris and surrounding terrain. images obtained during MESSENGER's January 2008 flyby of Mercury revealed that the Caloris basin is similar to 15% larger than previously estimated and moderately elliptical (similar to 1525 by similar to 1315 km). Basin-related sculpture and secondary craters are dispersed widely in areas surrounding the basin, confirming the widespread significance of this event as a stratigraphic marker. Units mapped around Caloris on the basis of Mariner 10 data are generally recognized in regions observed for the first time by MESSENGER, including most facies of the Caloris Group (the Caloris Montes, Odin Formation, and Van Eyck Formation). The only unit without obvious exposures in MESSENGER images is the Nervo Formation, which was originally interpreted as impact melt or fallback ejecta. New measurements of the size-frequency distribution of impact craters both within the Caloris basin and on surrounding units, particularly the Odin Formation, support the hypothesis that the vast majority of circum-Caloris plains postdate the basin and are likely volcanic. The MESSENGER observations re-emphasize the importance of understanding the exterior stratigraphy of the basin in order to utilize the Caloris event as a discrete time horizon in the geological history of Mercury. (C) 2009 Elsevier B.V. All rights reserved.