Abstract Sinuous collapse chains and skylights in lunar and Martian volcanic regions have often been interpreted as collapsed lava tubes (also known as pyroducts). This hypothesis has fostered a forty years debate among planetary geologists trying to define if analogue volcano-speleogenetic processes acting on Earth could have created similar subsurface linear voids in extra-terrestrial volcanoes. On Earth lava tubes are well known thanks to speleological exploration and mapping in several shield volcanoes, with examples showing different genetic processes (inflation and overcrusting) and morphometric characters. On the Moon subsurface cavities have been inferred from several skylights in Maria smooth plains and corroborated using gravimetry and radar sounder, while on Mars several deep skylights have been identified on lava flows with striking similarities with terrestrial cases. Nonetheless, the literature on this topic is scattered and often presents inaccuracies in terminology and interpretation. A clear understanding of the potential morphologies and dimensions of Martian and lunar lava tubes remains elusive. Although it is still impossible to gather direct information on the interior of Martian and lunar lava tube candidates, scientists have the possibility to investigate their surface expression through the analysis of collapses and skylight morphology, morphometry and their arrangement, and compare these findings with terrestrial analogues. In this review the state of the art on terrestrial lava tubes is outlined in order to perform a morphological and morphometric comparison with lava tube candidate collapse chains on Mars and the Moon. By comparing literature and speleological data from terrestrial analogues and measuring lunar and Martian collapse chains on satellite images and digital terrain models (DTMs), this review sheds light on tube size, depth from surface, eccentricity and several other morphometric parameters among the three different planetary bodies. The dataset here presented indicates that Martian and lunar tubes are 1 to 3 orders of magnitude more voluminous than on Earth, and suggests that the same processes of inflation and overcrusting were active on Mars, while deep inflation and thermal entrenchment was the predominant mechanism of emplacement on the Moon. Even with these outstanding dimensions (with total volumes exceeding 1 billion of m3), lunar tubes remain well within the roof stability threshold. The analysis shows that aside of collapses triggered by impacts/tectonics, most of the lunar tubes could be intact, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes.

中文翻译：

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地球、月球和火星上的熔岩管：比较行星学揭示的熔岩管大小和形态的综述

摘要 月球和火星火山地区的蜿蜒坍塌链和天窗经常被解释为坍塌的熔岩管（也称为火管）。这一假设在行星地质学家之间引发了 40 年的争​​论，试图确定作用在地球上的类似火山-洞穴生成过程是否会在地外火山中产生类似的地下线性空隙。在地球上，熔岩管因在几个盾状火山中的洞穴学探索和测绘而闻名，其中的例子显示了不同的遗传过程（膨胀和过度结壳）和形态特征。从玛丽亚光滑平原的几个天窗推断出月球地下空洞，并使用重力测量和雷​​达测深仪加以证实，而在火星上，已经在熔岩流上发现了几个深天窗，与地球上的案例有着惊人的相似之处。尽管如此，关于这个主题的文献是零散的，并且经常在术语和解释方面存在不准确之处。对火星和月球熔岩管的潜在形态和尺寸的清晰理解仍然难以捉摸。尽管仍然无法直接收集火星和月球熔岩管候选者内部的信息，但科学家们有可能通过分析坍塌和天窗形态、形态测量及其排列来研究它们的表面表现，并将这些发现与地球类似物进行比较. 在这篇评论中，概述了陆地熔岩管的最新技术，以便与火星和月球上的熔岩管候选坍塌链进行形态学和形态测量比较。通过比较来自地球类似物的文献和洞穴学数据，以及测量卫星图像和数字地形模型 (DTM) 上的月球和火星坍塌链，这篇综述揭示了三个不同行星之间的管道尺寸、距地表深度、偏心率和其他几个形态测量参数。身体。此处提供的数据集表明，火星管和月球管的体积比地球上的大 1 到 3 个数量级，并表明火星上存在相同的膨胀和过度结壳过程，而深度膨胀和热固结是侵位的主要机制在月球上。即使具有这些出色的尺寸（总体积超过 10 亿立方米），月球管仍然很好地保持在屋顶稳定性阈值内。分析表明，除了由撞击/构造引发的坍塌外，大多数月球管可能完好无损，这使月球成为地下探索和潜在沉降的非凡目标，在熔岩管的广泛保护和稳定环境中。