More than 65 years ago, W.H. Mathews published a seminal paper in American Journal of Science describing the Table, an iconic, flat-topped volcano in southern British Columbia, Canada. The Table is recognized as the type-example of a glaciovolcanic lava-dominated tuya. We use field mapping, 3-D photogrammetry, lithofacies identification and 40Ar/39Ar geochronology to re-examine the emplacement origins of this unique volcanic edifice. The Table is a steep-sided, flat-topped mass of dense, porphyritic andesite preserving a near-original outer surface of hackly fractured aphanitic material. The age of the edifice is 100 ± 12 ka. A new model for the emplacement involves dike injection and endogenous inflation within an overlying ice mass that is estimated to have been ∼250 to 350 m thick. The model assumes that the edifice expanded outwardly as an elliptical cylinder, endogenously inflating and melting an equal volume of ice. The thermal exchange between the expanding massif and the melting ice operates across a subvertical, well-drained, enveloping carapace of quench breccia. For effusion rates of 0.5 to 2 m3 s−1, marginal heat fluxes are 43 to 186 W m−2, implying low overall heat transfer coefficients (0.04 to ∼0.18 W m−2 K−1). The total volume of ice melted serves as a calorimeter and constrains the average thickness (∼3 m) and properties (thermal conductivity; 0.1 – 0.4 W m−1 K−1) of the breccia carapace. The heat transfer efficiency of intermediate lava-dominated tuyas is significantly lower (∼2 %) than reported for other glaciovolcanic systems (commonly ∼45 – 77 %) but similar to that found for block-lava flows and lava tubes.

中文翻译：

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The Table，不列颠哥伦比亚省南部的一座平顶火山：重温

65 多年前，WH Mathews 在美国科学杂志上发表了一篇开创性的论文，描述了位于加拿大不列颠哥伦比亚省南部的一座标志性平顶火山。该表被认为是冰川火山熔岩主导的图雅的典型例子。我们使用野外测绘、3-D 摄影测量、岩相识别和 40Ar/39Ar 地质年代学来重新检查这个独特的火山建筑的侵位起源。台面是陡峭的、平顶的致密斑状安山岩块，保留了近乎原始的粗糙断裂隐晶质材料的外表面。大厦的年龄是 100 ± 12 ka。一种新的就位模型涉及到上覆冰块内的堤防注入和内生膨胀，估计厚度约为 250 至 350 m。该模型假设大厦向外膨胀为椭圆圆柱体，内生地膨胀并融化等体积的冰。膨胀的地块和融化的冰层之间的热交换是通过一个近垂直的、排水良好的、包围着急冷角砾岩的甲壳进行的。对于 0.5 至 2 m3 s-1 的流出率，边际热通量为 43 至 186 W m-2，这意味着整体传热系数较低（0.04 至 ~0.18 W m-2 K-1）。融化的冰的总体积用作热量计，并限制角砾壳的平均厚度（~3 m）和特性（热导率；0.1 – 0.4 W m-1 K-1）。