The Hopi Buttes volcanic field (HBVF) is located on the Colorado Plateau, Northern Arizona. In this Miocene volcanic field, the erosion level increases southward, allowing the study of maar-diatreme volcanoes from top (posteruptive crater infill and ejecta ring) to bottom (lower diatreme). The Twin Peaks volcanic complex consists mostly of two hills (North Peak and South Peak) with thick lavas at their summits and pyroclastic rocks underneath. In the HBVF, such volcanic remnants have received little scientific attention so far, despite their relative abundance. Our field observations allow us to interpret the North and South Peaks as remnants of two maar-diatreme volcanoes which evolved into lava lakes filling the craters. Within the complex, we distinguish four volcanic units (from unit 1 at the bottom to unit 4 at the top). On the basis of the field description of the deposits and the componentry measurements, we suggest that unit 1 is phreatomagmatic, unit 2 is phreato-strombolian (with mixed phreatomagmatic and strombolian characteristics), unit 3a is phreato-hawaiian (with mixed phreatomagmatic and hawaiian characteristics), unit 3b is hawaiian (formed by lava fountains) and unit 4 consists of lava lakes filling the maar craters. There is therefore a progressive evolution from a purely phreatomagmatic eruptive style, which excavated the craters and diatremes and partly filled them, to magmatic explosive to nonexplosive eruptive styles, which filled the maar craters up to the pre-eruptive surface. We discuss traditional criteria used to distinguish phreatomagmatic from magmatic eruptive styles in ultramafic to mafic maar-diatreme volcanoes.

中文翻译：

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maar-diatremes 中的岩浆与岩浆喷发类型：亚利桑那州纳瓦霍族霍皮巴特斯火山场双峰的案例研究

霍皮巴特斯火山场 (HBVF) 位于亚利桑那州北部的科罗拉多高原。在这个中新世火山场中，侵蚀水平向南增加，可以从顶部（喷发后的火山口填充物和喷出物环）到底部（下部火山口）研究玛尔地层火山。双峰火山群主要由两座山（北峰和南峰）组成，山顶有厚厚的熔岩，下面有火山碎屑岩。在 HBVF 中，这种火山残留物尽管相对丰富，但迄今为止很少受到科学关注。我们的实地观察使我们能够将北峰和南峰解释为两座马尔迪亚特雷姆火山的遗迹，这些火山演变成充满火山口的熔岩湖。在复合体中，我们区分了四个火山单元（从底部的单元 1 到顶部的单元 4）。根据矿床的野外描述和组分测量，我们认为单元 1 为潜水岩浆，单元 2 为潜水-斯特龙波阶（具有潜水岩浆和斯特龙博利混合特征），单元 3a 为潜水-夏威夷（具有潜水岩浆和夏威夷混合特征）特征），单元 3b 是夏威夷（由熔岩喷泉形成），单元 4 由充满玛尔火山口的熔岩湖组成。因此，从纯粹的岩浆喷发类型（挖掘火山口和火山岩并部分填充它们）到岩浆爆炸到非爆炸性喷发样式（将玛尔火山口填满到喷发前的表面）逐渐演变。我们讨论了用于区分超镁铁质火山到镁铁质火山岩浆火山中的岩浆喷发样式和岩浆喷发样式的传统标准。