伊西底斯平原是中国首次火星探测任务“天问一号”的预选着陆区之一，地表广泛发育指纹地形和壁垒撞击坑。壁垒撞击坑具有一层或多层流态化的连续溅射物，一般被认为是地下富含水/冰的地层（以下简称“地下水冰层”）与超高速撞击体作用的产物，是分析火星当前和过去地下水冰层的关键研究对象。基于高分辨率影像，本文采用影像解译、形貌分析、撞击坑统计定年等方法，开展了伊西底斯平原壁垒撞击坑的遥感综合分析。解译发现该平原目前共存在120个壁垒撞击坑，它们的最小直径为1.5 km，连续溅射物平均分布在撞击坑周围约1.3个半径范围之内，且外观不规则程度（弯曲度）高。采用撞击坑直径—频率分布定年方法确定了15个连续溅射物保存完整的壁垒撞击坑的绝对模式年龄（地质年龄），发现它们全部形成于亚马逊纪。根据连续溅射物与指纹地形的空间叠加关系，本文推断构成指纹地形的锥状物形成于2.38—3.24 Ga（早亚马逊纪）。它们更可能是大量岩浆流过湿润或冰冻地面时下覆（融化）水分迅速气化而发生爆裂并冲破岩浆形成的无根锥/伪火山口。根据撞击坑直径和挖掘深度之间的经验关系，本文揭示伊西底斯平原有利于形成壁垒撞击坑的地下水冰层的平均埋藏深度至少稳定保持在1 km，并可能因火星自转倾角周期性变化对气候的影响而发生0.1 km的小幅上升或下降。本文研究成果对于重建伊西底斯平原地下水冰环境演变历史具有重要科学意义，并有望得到中国“天问一号”巡视器和轨道器次表层探测雷达探测结果的验证。

Isidis Planitia is a potential landing area for China’s first Mars exploration mission “Tianwen-1.” Fingerprint terrain and rampart crater are widely developed on the surface of Isidis Planitia. The rampart crater has one or more fluidized ejecta, which is generally considered the product of the interaction between the subsurface ice-rich layer and the hypervelocity impactor. Considering that water is an essential nutrient that nurtures and maintains all known life forms, the water evolution history of Mars has always been a research hotspot in the planetary community. Therefore, a detailed study on the rampart craters in the Isidis Planitia can provide strong constraints for analyzing the current and past subsurface ice-rich layers in this region.Through the use of high-resolution optical images obtained by the Context Camera (CTX) onboard the Mars Reconnaissance Orbiter (MRO), a comprehensive study has been performed on the rampart craters in the Isidis Planitia using image interpretation, morphologic analysis, and crater count dating. The morphometric parameters of the rampart craters, including ejecta mobility and lobateness, are calculated for all the identified rampart craters in this region. Moreover, the absolute model ages (AMAs) of representative rampart craters that have intact fluidized ejecta are determined by the Crater Size-Frequency Distribution (CSFD) measurement.This study found that 120 rampart craters are currently located in the Isidis Planitia. Their minimum diameter is 1.5 km, and most of their layered ejecta are highly irregular (sinuous) and extend to approximately 1.3 crater radii from the rim. The AMAs of 15 rampart craters reveal that they all formed in the Amazonian. According to the spatial superposition relationship between the rampart crater and the fingerprint terrain, this study infers that that the cones of the fingerprint terrain were formed in the Early Amazonian between 2.38-3.24 Ga, and they are more likely to be rootless cones/pseudo craters formed by explosive steam that break through the lava surface when a voluminous magma flows through wet or frozen ground and vaporizes the underlying (melt) water. According to the empirical formula between crater diameter and excavation depth, this study reveals that the depth of the subsurface ice-rich layer that is conducive to the formation of rampart crater in the Isidis Planitia is currently stable at least approximately 1 km and may rise or fall slightly by 0.1 km because of the effect of periodic changes of Mars' tilt (obliquity) on the climate.The results of this study are of great scientific significance for reconstructing the evolution history of the subsurface ice environment in the Isidis Planitia and are expected to be verified by the detection of the subsurface exploration radar onboard the rover and orbiter of the “Tianwen-1” probe.