NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Southwest Research Institute, Boulder, CO, USA.
Science. 2020 Nov 6;370(6517). doi: 10.1126/science.abc3557. Epub 2020 Oct 8.
The composition of asteroids and their connection to meteorites provide insight into geologic processes that occurred in the early Solar System. We present spectra of the Nightingale crater region on near-Earth asteroid Bennu with a distinct infrared absorption around 3.4 micrometers. Corresponding images of boulders show centimeters-thick, roughly meter-long bright veins. We interpret the veins as being composed of carbonates, similar to those found in aqueously altered carbonaceous chondrite meteorites. If the veins on Bennu are carbonates, fluid flow and hydrothermal deposition on Bennu's parent body would have occurred on kilometer scales for thousands to millions of years. This suggests large-scale, open-system hydrothermal alteration of carbonaceous asteroids in the early Solar System.
小行星的组成及其与陨石的联系为我们深入了解早期太阳系发生的地质过程提供了线索。我们展示了近地小行星贝努（Bennu）夜莺陨石坑地区的光谱，在 3.4 微米附近有明显的红外吸收。相应的巨石图像显示出厘米厚、大约一米长的明亮脉。我们推断这些脉是由碳酸盐组成的，类似于在水蚀变的碳质球粒陨石中发现的碳酸盐。如果贝努上的脉是碳酸盐，那么贝努母体上的流体流动和热液沉积将在数千年到数百万年内以公里尺度发生。这表明在早期太阳系中，碳质小行星经历了大规模的开放式热液蚀变。
