【摘要】 热和组分密度异常共同驱动的动态金幔柱解析模式给出金幔柱在金幔中上升的历史．当金幔柱到达岩石层底时其头部的特征量是5个独立变量的函数：（1）金幔柱起源的深度；（2）金幔粘性系数；（3）源温度异常值；（4）源组分与热密度异常之比；（5）金幔柱的浮力通量．基于新的Mapellan数据，金星表面上有360多个冠状和类冠状构造已被发现，其中65％直径小于300km．这类小型冠状构造被认为是由具有下述特征的较小的金幔柱所形成：（1）最大直径小于300km；（2）当其头部到达岩石层底时，过剩温度足以产生部分熔融层，应高于150K；（3）被冠状构造下面的金幔柱带上来的总浮力有能力支撑冠状构造隆起的总质量．用这3个条件分析数值结果并约束金幔柱的源参数，根据本文的数值实验结果，金星上的小型冠状构造可能是起源于上金幔小于1000km深度的动态金幔柱形成的．更多还原

【Abstract】 An analytic model of starting plumes driven by both thermal and compositional density anomalies is used to infer their history of rising through the venusian mantle.The characteristics of the plume heads when they reach the base of the lithosphere are given as functions of five independent variables: (1) depth of the plume origin, (2)mantle viscosity, (3) source temperature anomaly, (4) the ratio of the compositional to the thermal density source anomaly, and (5) the buoyancy flux of the plume. On the basis of new Magellan data more than 360 coronae and coronalike structures have been observed on the surface of Venus, and 65% of them are less than 300 km in diameter. Such kind of small coronae are proposed to be formed by small venusian manhe plumes which should have: (1) maximum diameters of less than 300km, (2)excess temperature high enough to form a partially molten layer, at least higher than 150K. when their top touched the base of the lithophere, and (3) a total buoyancy carried up by the plume beneath a corona which can support the total weight of the corona-swell. These three conditions are used to analyse the numerical results and to constrain the source parameters of the plumes. According to the results of numerical experiments in the present paper it is argued that the small coronae on Venus may be formed by starting mantle plumes which have a shallow origin, i. e. in the upper mantle in a depth less than 1000 km.更多还原