Abstract Imdr Regio is a volcano dominated young topographic rise of Venus whose most prominent volcanic structure, Idunn Mons, shows indications of being recently active. Despite its scientific relevance, this region has been poorly studied to date. Idunn Mons is spatially related to a rift system, Olapa Chasma, which dominates the topographic rise. The rift fractures around Idunn Mons form an “hourglass” pattern indicating a close tectonic interaction between the volcano and Olapa Chasma. The principal aim of this work is to understand whether Olapa Chasma has been tectonically active in the recent geologic past. For this purpose, we analyzed Sandel crater (45.7°S/211.7°E), an impact structure 17.9 km in diameter situated NW of Idunn Mons, and we used it as a local stratigraphic marker. Observing the variations in the radar brightness and crosscutting relationships, we produced a local geologic map of impact deposits, volcanic materials and tectonic structures surrounding the crater. Then, we used the map to reconstruct the local stratigraphy and relative ages of the materials for deciphering the temporal relations between the crater and volcano-tectonic activity. Following the existing degradation models for Venusian craters we could also estimate a time range for the formation of Sandel crater. The results show that its formation convincingly occurred during the period between 0.5 T and 0.15 T, where T is the average age of the surface of Venus. We present here a line of evidence that, at least in its last stage, the tectonic activity characterizing Olapa Chasma and Idunn Mons postdate the formation of Sandel crater. Building on the findings from previous studies, we hypothesize that not only volcanism but also the tectonic processes behind the formation of Idunn Mons and Olapa Chasma are geologically recent. For this reason, we refer to Olapa Chasma and Idunn Mons as a recently active volcano-tectonic system of Venus, which deserves to be a potential target site for future missions to Venus, including investigations of surface volcanism and seismicity.

中文翻译：

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金星 Sandel 火山口的局部地层关系：Imdr Regio 最近火山构造活动的可能证据

摘要 Imdr Regio 是一座以火山为主的年轻金星上升地形，其最突出的火山结构 Idunn Mons 显示出最近活跃的迹象。尽管它具有科学相关性，但迄今为止，对该地区的研究很少。Idunn Mons 在空间上与主导地形隆起的 Olapa Chasma 裂谷系统有关。伊登蒙斯周围的裂谷裂缝形成“沙漏”图案，表明火山和奥拉帕峡谷之间存在密切的构造相互作用。这项工作的主要目的是了解奥拉帕峡谷在最近的地质历史中是否在构造上活跃。为此，我们分析了 Sandel 陨石坑 (45.7°S/211.7°E)，这是一个位于 Idunn Mons 西北方向的直径 17.9 公里的撞击结构，我们将其用作当地的地层标记。观察雷达亮度和横切关系的变化，我们制作了撞击坑周围的撞击沉积物、火山物质和构造结构的局部地质图。然后，我们使用该地图重建当地地层和材料的相对年龄，以破译火山口与火山构造活动之间的时间关系。根据金星陨石坑的现有退化模型，我们还可以估计桑德尔陨石坑形成的时间范围。结果表明，它的形成令人信服地发生在 0.5 T 到 0.15 T 之间，其中 T 是金星表面的平均年龄。我们在此提供了一系列证据，表明至少在其最后阶段，表征奥拉帕峡谷和伊登蒙斯的构造活动晚于桑德尔陨石坑的形成。基于先前研究的结果，我们假设不仅火山活动而且 Idunn Mons 和 Olapa Chasma 形成背后的构造过程在地质上都是最新的。出于这个原因，我们将奥拉帕峡谷和伊登蒙斯称为最近活跃的金星火山构造系统，值得成为未来金星任务的潜在目标地点，包括地表火山活动和地震活动的调查。