摘要
Marius Hills火山高原位于月球正面风暴洋区域,具有丰富的火山建造遗迹,包括火山穹窿,火山锥和月溪等.该区域保留了月海火山作用的典型特征,为研究月海热演化历史提供了有利的窗口.受以往观测数据类型的限制,大多数研究都是针对该区域的表面形貌和物质成分特性的分析,缺乏对月海火山次表层和内部结构等重要火山特征的研究.本文利用月球正面高分辨率地形和重力数据,结合附加表面和内部载荷的弹性薄壳均衡模型,对该火山区域的平均月壳密度,岩石圈弹性厚度和表面内部载荷比等参数进行定量约束.结果显示该区域月壳密度较高,为3040 kg m 3,具有典型的月海玄武质的密度特征;地下可能存在侵位较浅的岩浆房或岩床状侵入体或是岩浆充填了壳层松散的区域;该区域的岩石圈弹性厚度较小,约为4 km,反映该区域在形成过程中富集了大量的热,该结果与通过光谱矿物分析得到的风暴洋区域富集产热元素(如钍)的结果一致.
Marius Hills is a large volcanic complex on the Oceans Procellarum of the lunar nearside. Numerous volcanic features, including domes, cones, and rilles occur in this region. Due to limitations in lunar remote sensing data, most previous studies on this region focused on its morphological and geochemical properties but little was known about the subsurface and interior structures of this volcanic complex. Knowledge of the local crustal density is meaningful to both determine the composition for this volcanic complex and understand the crustal evolutionary history for this region. Constraining the lithospheric thickness in this region is helpful to estimate the heat flux at the time of volcanic loading, which is a crucial parameter to study the thermal evolutionary history of the nearside mantle. Here, we applied a localized gravity and topography admittance analysis for the Marius Hills region to constraint its crustal density and lithospheric thickness. The gravity filed is modeled using a thin elastic lithspheric model that considers both surface and subsurface loads. Localized admittance and correlations spectra are used to constrain these modeled parameters. The best-fit crustal density in our model is -3040 kg m 3, which is much higher than the average lunar crustal density as 2550 kg m-3, indicating that magma chambers or sills has intruded to the shallow crust and/or that intrusive magma has filled up the porous subsurface crust. The total volume of basalts emplaced in the Marius Hills region is ~2.9~104 km3, suggesting that Marius Hills is a major volcanic center in the Oceanus Procellarum. The best-fit lithospheric thickness of this region is constrained to be as small as -4 km, indicating that a significant amount of heat production elements have concentrated in this region during the formation of the volcanic complex. This result is consistent with the previous spectral studies that heat production elements （such as thorium） are more abundant in the Oceanus Procellarum.
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2013年第11期1395-1402,共8页
Scientia Sinica Physica,Mechanica & Astronomica
基金
中国博士后科学基金(编号:2012M520070)
中央高校新青年教师科研启动基金(编号:CUG120810)
嫦娥专项基金(编号:CUG130106)资助
