Replication Data for: Lateral variation in bulk density and porosity of the upper Lunar crust from high-resolution gravity and topography data: comparison of different analysis techniques.

We map lateral variations in bulk density of the upper lunar highland crust using the most recent GRAIL gravity field solution of degree and order 1500 in combination with LOLA topography data, both truncated to an upper limit of degree and order 700. Our maps have a spatial resolution of 0.75, where each grid point was calculated using circular analysis regions of 3 radius. We apply two methods, which yield similar results for most parts of the study area. The first method minimizes the correlation between topography and Bouguer anomalies, the second maximizes the smoothness of the Bouguer anomalies. Both approaches suffer in the case that terrain is flat and lacks topographic features; consequently, this is where results from the two methods differ. We also mapped porosity of the crust using grain densities derived from Lunar Prospector spectrometry and sample analysis. It appears that variations in bulk density are mostly related to differences in crustal porosity. We find that high porosity is often associated with areas of impact basins. This confirms earlier studies, that impacts changed the geophysical characteristics of the lithosphere sustainably and that the high porosity of the upper lunar crust is most likely impact induced.

本研究利用最新的1500阶次GRAIL（Gravity Recovery and Interior Laboratory，重力回溯及内部结构实验室）重力场解，结合截断至700阶球谐阶次的LOLA（Lunar Orbiter Laser Altimeter，月球轨道激光测高仪）地形数据，绘制了月球高地地壳上部体密度的横向变化分布。本次生成的地图空间分辨率为0.75，每个网格点的计算均采用半径为3的圆形分析区域。本研究采用两种分析方法，在研究区的绝大部分区域中，二者得到的结果具有较高一致性。第一种方法通过最小化地形与布格异常（Bouguer anomalies）之间的相关性进行求解，第二种方法则通过最大化布格异常的空间平滑度完成计算。但两种方法均存在适用局限：当地形平坦且缺乏地形特征时，二者的计算结果会出现显著差异。本研究同时基于月球勘探者号（Lunar Prospector）光谱测量数据与样品分析得到的矿物颗粒密度，绘制了月球地壳孔隙度分布地图。分析结果表明，体密度的横向变化主要与地壳孔隙度的差异相关。研究发现，高孔隙度区域通常与撞击盆地的分布区域相重合。这一结果验证了此前的研究结论：撞击作用可持续地改变岩石圈的地球物理特性，而月球高地地壳上部的高孔隙度极有可能由撞击事件诱发形成。