金星的重力场与地壳厚度

发布时间：2018-09-10 11:45

【摘要】：利用Megellan号探测器确定的重力场和地形模型资料,进一步分析了金星重力场特征,并利用金星地幔对流模型建立了动力学模型的大地水准面地形比,即动力学模型导纳.然后利用该动力学模型导纳,基于2~40阶大地水准面是由与动力学过程相联系的岩石圈下密度异常产生的假定,在扣除重力场和地形的动力学影响的基础上,利用球面Parker公式反演了金星地壳的厚度.结果显示:金星重力场和地形受到金星地幔动力学过程的强烈影响;金星地壳也对地形产生显著影响;金星地壳厚度变化范围主要集中在28~70 km,Ishtar高原以及Aphrodite高原西部的Ovda和Thetis区域是金星地壳最厚的区域(大于50 km),该区的高地形主要与地壳均衡相关,这与其是古老陆地残留的推测一致.在Beta,Themis,Dione,Eistla,Bell和Lada区域地壳厚度较薄,且与地形无明显相关.特别是在Aphrodite高原东部的Atla和Imdr区域,地壳厚度与周围区域地壳厚度基本一致.这种特征与这些区域的高地形主要是由热柱的动力学过程引起的假定相一致.与包含动力学影响得到的金星地壳厚度相比,扣除动力学影响后得到的金星地壳厚度能更好地反映金星地壳的演化和内部动力学过程.
[Abstract]:Based on the data of gravity field and terrain model determined by Megellan detector, the characteristics of Venus gravity field are further analyzed, and the geoid topography ratio of the dynamic model is established by using the Venus mantle convection model, that is, the dynamic model admittance. Based on the assumption that the geoid of order 240 is generated by the density anomaly under the lithosphere associated with the dynamic process, the dynamic effects of gravity field and topography are deducted. The thickness of the crust of Venus is inversed by using the spherical Parker formula. The results show that the gravity field and topography of Venus are strongly influenced by the dynamic process of the mantle of Venus, and the crust of Venus also exerts a significant influence on the topography. The variation range of crustal thickness of Venus is mainly concentrated in the 2870 km,Ishtar Plateau and the Ovda and Thetis regions in the western part of the Aphrodite Plateau, which is the thickest area of the crust of Venus (> 50 km),). The high topography of the area is mainly related to the crustal equilibrium. This is consistent with speculation that it is an ancient land residue. The crustal thickness in Beta,Themis,Dione,Eistla,Bell and Lada regions is relatively thin, and there is no obvious correlation between the crust thickness and topography. Especially in the Atla and Imdr regions of the eastern Aphrodite plateau, the crustal thickness is basically the same as that in the surrounding area. This characteristic is consistent with the assumption that the high topography of these regions is mainly caused by the dynamic process of the hot column. Compared with the thickness of the crust of Venus which includes the dynamic influence, the thickness of the crust of Venus obtained after the dynamic influence can better reflect the evolution of the crust of Venus and the internal dynamic process.
【作者单位】：蒙城地球物理国家野外科学观测研究站;中国科学技术大学地球和空间科学学院地震与地球内部物理实验室;
【基金】：国家自然科学基金项目(批准号:91014005,40774045)资助
【分类号】：P185.2

【共引文献】