NASA's Magellan mission revealed that many Venus highlands exhibit low radar emissivity values at higher altitudes. This phenomenon is ascribed to the presence of minerals having high dielectric constants, produced or stabilized by temperature‐dependent chemical weathering between the rocks and the atmosphere. Some large volcanoes on Venus have multiple reductions of radar emissivity at varying altitudes. The authors present morphological maps of major lava flow units at Maat, Ozza, and Sapas montes and compare them to radar emissivity. Sapas has a single reduction in emissivity values at 6,054.6 km, while Maat and Ozza have several reductions at altitudes of 6,052.5–6,056.7 km. Emissivity values are highly spatially correlated to individual lava flows indicating that minerals in the rocks control the emissivity signature. The emissivity patterns at these volcanoes require at least four individual ferroelectric mineral compositions in the rocks that are highly conductive at Curie temperatures of 693–731 K. These temperatures are compatible with chlorapatite and some perovskite oxides. Modeling the minimum volumes of ferroelectrics (10–100s ppm) shows the volume and type of ferroelectric may vary over the lifetime of a single volcano. The modeled volumes of ferroelectrics in Ozza and Sapas are greater than in Maat, consistent with the production of ferroelectrics via weathering over a longer period of time, and supporting the idea that Maat has younger volcanic activity. The stratigraphic relationship of Maat's youngest flows with impact craters may indicate the timeframe of the production of specific ferroelectrics via chemical weathering is over 9–60 Ma.

中文翻译：

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根据麦哲伦雷达发射率得出的金星阿特拉区各个熔岩流的独特矿物学和年龄


美国宇航局的麦哲伦任务显示，许多金星高地在较高海拔处表现出较低的雷达发射率值。这种现象归因于具有高介电常数的矿物的存在，这些矿物是由岩石和大气之间与温度相关的化学风化作用产生或稳定的。金星上的一些大型火山在不同高度处雷达发射率会多次降低。作者展示了马特山、奥扎山和萨帕斯山主要熔岩流单元的形态图，并将其与雷达发射率进行了比较。 Sapas 在 6,054.6 km 处发射率值出现单次降低，而 Maat 和 Ozza 在 6,052.5–6,056.7 km 高度处出现多次发射率降低。发射率值与各个熔岩流在空间上高度相关，表明岩石中的矿物质控制着发射率特征。这些火山的发射率模式需要岩石中至少有四种单独的铁电矿物成分，这些成分在 693-731 K 的居里温度下具有高导电性。这些温度与氯磷灰石和一些钙钛矿氧化物相容。对铁电体最小体积 (10–100s ppm) 的建模表明，铁电体的体积和类型可能在单个火山的生命周期内发生变化。奥扎和萨帕斯的铁电体模型体积大于马特，这与通过较长时间的风化产生铁电体的情况一致，并支持马特火山活动较年轻的观点。马特最年轻的流与撞击坑的地层关系可能表明，通过化学风化产生特定铁电体的时间范围超过 9-60 Ma。