Subsurface structures of large volcanic complexes on the nearside of the Moon: A view from GRAIL gravity
Subsurface structures of large volcanic complexes on the nearside of the Moon: A view from GRAIL gravity
复制标题
月球近侧大型火山复合体的地下结构：GRAIL 引力的视角
DOI：
10.1016/j.icarus.2014.09.009
复制
发表时间：
2014
期刊：
影响因子：
3.2
通讯作者：
Long Xiao
中科院分区：
文献类型：
--
作者：
Qian Huang;Zhiyong Xiao;Long Xiao
月球附近的大型火山复合体，如吕姆克山、阿里斯塔克斯高原和马里乌斯山，可能是强烈而持续的岩浆活动的地点。这些火山杂岩，最近被认为是盾状火山，通常位于区域高海拔地区，有些具有相对局部的正重力异常。应用本地化的光谱分析从重力恢复和内部实验室（GRAIL）的使命和地形数据从月球勘测轨道飞行器（LRO）航天器返回的高分辨率重力数据，我们研究这些火山复合体的地下结构。重力信号预测使用薄弹性岩石圈模型，考虑表面和地下负荷。最佳拟合地壳和载荷密度表明，吕姆克山、马里乌斯山、加德纳山和开普勒山的地形高点主要由密度超过2850 kg m−3的物质组成，这与侵位火成岩的密度一致。阿里斯塔克斯高原和霍腾修斯都有相对较低的地壳和表面负荷密度，平均值约为2550 kg m−3，这与月球高地地壳的平均体积密度非常一致。这些结果以及地表多个火山机构的证据表明，Rümker Hills，Marius Hills，Gardner和Kepler的浅壳主要由密集的侵入/喷出岩浆单元组成，而Aristarchus Plateau和Hortensius的浅壳主要由低密度物质组成，只有少量的叠加火山物质。为了进一步约束这些火山复合体下方的地下结构，我们分析了这些地区的布格重力异常。结果表明，可能是固化侵入体的致密物质存在于Rümker Hills，Marius Hills，Gardner和Prinz之下，但在Aristarchus Plateau，Hortensius，Kepler或Cauchy之下没有检测到实质性的致密物质。这些大型火山杂岩的不同地下结构表明，即使是在同一地质时期形成的火山岩，在月球近侧的火山活动风格也是不同的。
The lunar nearside large volcanic complexes, such as the Rümker Hills, Aristarchus Plateau, and Marius Hills are likely sites of intense and sustained magmatic activity. These volcanic complexes, recently proposed to be shield volcanoes, are generally located at regionally high elevations and some feature relatively well-localized positive gravity anomalies. Applying localized spectral analyses on high-resolution gravity data obtained from the Gravity Recovery and Interior Laboratory (GRAIL) mission and topography data returned from the Lunar Reconnaissance Orbiter (LRO) spacecraft, we study the subsurface structures of these volcanic complexes. The gravity signal is predicted using a thin elastic lithospheric model that considers both surface and subsurface loads. Best-fit crustal and load densities show that the topographic highs of Rümker Hills, Marius Hills, Gardner and Kepler are mainly composed of material that has a density of more than 2850 kg m−3, which is consistent with that of emplaced igneous rocks. Both the Aristarchus Plateau and Hortensius have relatively lower crustal and surface load densities, with mean values around 2550 kg m−3, which are well consistent with the average bulk density of the lunar highland crust. These results, together with evidence of multiple volcanic edifices on the surface, suggest that the shallow crusts of the Rümker Hills, Marius Hills, Gardner and Kepler are mainly composed of dense intrusive/extrusive magmatic units, and those of the Aristarchus Plateau and Hortensius are mainly composed of low density materials with only small amounts of superimposed volcanic material. To further constrain the subsurface structures beneath these volcanic complexes, we analyze the Bouguer gravity anomalies for these regions. Results show that dense materials that might be solidified intrusions exist beneath Rümker Hills, Marius Hills, Gardner and Prinz, but no substantial dense materials have been detected beneath the Aristarchus Plateau, Hortensius, Kepler or Cauchy. The different subsurface structures among these large volcanic complexes suggest that the volcanism style at the lunar nearside is different from each other, even for those formed at the same geological time.