Tectono-magmatic events on Venus and their implications for climate change

在地球上，人们越来越认识到，被称为大型火成岩省(LIP)的巨大火山事件(规模高达数百万立方公里)是快速气候变化的主要驱动因素，包括大规模灭绝(高达90%的生命被消灭)。*在金星上，一次主要的唇型火山活动发生在大约7亿年前的平均年龄，并释放了大量的二氧化碳。这导致了极端的温室气体变暖，目前的地表温度为450摄氏度(是烤箱的两倍)，大气密度是地球的90倍，由96%的二氧化碳组成。因此，金星表面没有液态水，因此没有明显的侵蚀。也没有板块构造。最近有人提出，在这次超级变暖事件之前，金星的条件更像地球，甚至包括海洋和河流的存在，以及生命的潜在存在。*我建议可以通过对两种类型的单元进行地质测绘(使用麦哲伦雷达数据)来评估这一金星显著的气候变化模型：广泛分布的玄武岩熔岩流和基底风格的地体。该模型将预测，金星上最早的玄武岩熔岩流是在较冷的(类似地球的)条件下侵位的，而后来的玄武岩熔岩流可能是在更热的条件下侵位的。此外，金星上最古老的岩石--燕尾岩(可能类似于加拿大地盾的基岩)，可能是在大规模全球变暖之前就位的，当时金星上可能有水侵蚀。*在地球上观察到的玄武岩流动的指导下，我的研究小组将绘制流动的长度和宽度、从粗糙(a‘a型)到光滑绳状(Pahoehoe型)流动的过渡模式、年龄和体积关系等特征，并制定标准来区分在15oC(大气层)和450oC(地球大气的90倍)条件下侵位的金星熔岩流。*金星是最古老的金星岩石。如果神秘的陨石是在全球变暖事件之前形成的，那么它们的高水平变形一定发生在地球深处(可能有5公里深)，然后我们必须考虑这些岩石是如何带到地表的。在加拿大西部的科迪勒拉，深部的地壳岩石沿着大断层带到地表，并因侵蚀而暴露出来。我们绘制的金星地图将评估形成的深度和去顶的模式，包括水侵蚀的潜在作用。*这项关于玄武岩流动和地体的研究将开发出更好地描述金星戏剧性气候模型的技术，并提高对地球温室气体变暖的理解。这项研究将培养三名硕士和两名博士生。

On Earth, there is growing recognition that huge volcanic events (up to millions of cubic kilometres in scale) known as Large Igneous Provinces (LIPs) are major drivers of rapid climate change, including mass extinctions (where up to 90% of life was obliterated). ******On Venus, a major pulse of LIP-style volcanism occurred at a mean age of approximately 700 million years ago and released a massive volume of CO2. This caused extreme greenhouse warming to a current surface temperature of 450oC (twice as hot as your oven), and an atmosphere 90 times as dense as that of the Earth and composed of composed of 96% CO2. As a consequence, there is no liquid water on the surface of Venus and therefore no significant erosion. There is no plate tectonics either. It has been recently proposed that prior to this hyper-warming event that Venus had conditions that were more Earth-like, even including the presence of oceans and rivers, and the potential for life. ******I propose that this dramatic climate change model for Venus can be evaluated through geological mapping (using Magellan radar data) of two types of units: the widespread basaltic lava flows, and tesserae basement style' terranes. The model would predict that the earliest basaltic lava flows on Venus were emplaced during cooler (Earth-like) conditions, while the later basaltic flows would have been emplaced under the much hotter conditions. In addition, the oldest rocks on Venus, the tesserae (potentially similar to basement rocks like those of the Canadian shield), would be have been emplaced prior to the massive global warming at a time when there could have been water erosion on Venus. ******With guidance from observations of basaltic flows on Earth my research group will map features such as the length and width of flows, the transition patterns from rough (a'a type) to smooth ropey' (pahoehoe type) flows, age and volume relationships and other characteristics and develop criteria to distinguish Venusian lava flows that have been emplaced under 15oC (1 atmosphere) vs 450oC (90 times Earth's atmosphere) conditions.******Tesserae are the oldest Venusian rocks. If the enigmatic tesserae formed prior to the global warming event, then their high level of deformation must have occurred at depth in the Earth (perhaps >5 kilometres deep) and then we must consider how these rocks were brought to the surface. In the Cordillera of western Canada, deep crustal rocks are brought to the surface along great faults and exposed by erosion. Our mapping of tesserae will assess depth of formation and models of unroofing' including the potential role of water erosion.******This research on basaltic flows and tesserae terrane will develop techniques to better characterize the dramatic climate model of Venus, and improve the understanding of greenhouse warming on Earth. This research will train three MSc and two PhD students.***********