金星内部结构与动力学研究进展

Recent Advance in the Interior Structure and Dynamics of Venus

金星是一个与地球在大小、质量、组成和离太阳的距离等方面都非常相似的行星,但是现今金星不存在类似地球上的板块构造运动,也没有内生磁场。根据金星的重力和地形的研究显示金星的岩石圈比较厚。金星的大地水准面和地形的比值(导纳)比较大、相关性也很高,表明金星内部存在全球性的动力学过程。金星上存在约10个类似地球上夏威夷下方的地幔柱,最新的金星快车探测资料显示其中几个地幔柱存在近期的火山活动。另外对金星陨石坑数据的分析表明金星表面比较年轻,平均年龄大约为5亿年,这暗示着金星可能发生过全球性的表面更新,但金星的表面更新是一个灾难性的还是均匀的过程则存在很大的争议。同样存在争议的问题是金星过去是否存在类似当今地球的板块构造运动,是一直处于类似现今金星的停滞盖层对流,还是处于一种完全不同的对流模式?总的来说,金星的地幔对流模式与地球的以板块构造为特征的地幔对流模式显著不同。回顾了金星的重力、地形和表面构造等主要表面观测及其对金星内部结构和动力学的约束,总结了近年来对金星内部结构与动力学的一些认识,并对未来研究提出展望。

Venus is similar to the Earth in size,mass,composition and distance to the sun. However,Venus has neither plate tectonics nor dynamo that exists on the Earth. The lithosphere of Venus is very thick based on its topography and gravity. The admittance and correlation between Venusian geoid and topography are very high,suggesting that they are strongly influenced by the internal dynamical process of Venus. Analyses show that there may be 10 Hawaii-like mantle plumes in Venusian mantle. Data from Venus Express has shown evidence for recent active volcanism among several of these plumes. The distribution of impact craters on Venus shows that Venusian surface has a young age and the age is averaged about 500 Ma,suggesting that Venus may have experienced a global resurfacing event. However,whether this resurfacing is catastrophic or equilibrium is still under debate. It is also unclear whether Venus had plate tectonics in the past,is it always in stagnant lid regime,or might it have an entirely different mode?In general,the style of mantle convection on Venus is quite different from that of the Earth which is manifested by the plate tectonics. Here we reviewed the main observations including gravity,topography and surface tectonics which provide constrains on the interior structure and dynamics of Venus,and recent advance in the interior structure and dynamics of Venus. This review aims to provide new insights into the interior dynamics of Venus.