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首页> 外文期刊>Journal of Volcanology and Geothermal Research >The occurrence, vesiculation, and solidification of dense blue glassy pahoehoe
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The occurrence, vesiculation, and solidification of dense blue glassy pahoehoe

机译：致密的蓝色玻璃状pahoehoe的发生，囊泡和凝固

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Dense blue glassy pahoehoe occurs on the lower Kalapana flow field of Hawaii as limited breakouts at the base of tumuli and pressure rises or in localized depressions. Dense blue glassy pahoehoe differs from the more abundant spongy pahoehoe in that it has a distinctive silvery blue color, a poorly vesiculated glassy outer selvage, and lower extrusion temperature (～ 10℃ cooler). The color of blue glassy pahoehoe may be attributed to the concentration of iron and magnesium at the surface, whereas the golden color of the spongy pahoehoe is possibly the result of fluorine enrichment. The outer margin of the dense pahoehoe consists of three layers, developed in response to an increased cooling rate toward the surface. The outer glass selvage is less than 1 cm thick containing minor amounts of chromite, olivine, plagioclase, and augite. Inside the glassy rind is a ～ 5 mm thick transition zone characterized by increasing numbers and sizes of quenched plagioclase crystals and augite clusters. The interior of dense blue glassy pahoehoe is largely crystalline. Crystal size distribution (CSD) theory demonstrates that the formation and textures of plagioclase, pyroxene, and oxides are related to the cooling rates, growth rates (G), and nucleation rates (J) present in each layer of the dense pahoehoe. In contrast to the outer selvage, the crystalline interior typically contains numerous large coalesced vesicles as compared to the evenly vesiculated spongy pahoehoe. The enigmatic contrast between the poorly vesicular outer glassy selvage and the vesicular interior has been attributed to both lower and higher vapor contents of the dense pahoehoe. The higher density, lower extrusion temperatures, degassed outer glassy selvage, well-developed crystalline interior, and fluorine-deficient surface of dense blue glassy, as compared to spongy pahoehoe, indicate that blue glassy pahoehoe was stagnant long enough to exsolve considerable vapor in the lava tube system before extrusion.
机译：密集的蓝色玻璃状pahoehoe发生在夏威夷的较低的Kalapana流场中，这是由于在肿瘤底部发芽有限，压力升高或局部凹陷所致。致密的蓝色玻璃纤维pa头与丰富的海绵形pahoehoe的不同之处在于，它具有鲜明的银蓝色，较薄的泡沫状玻璃状外部边缘和较低的挤出温度（约低10℃）。蓝色玻璃状pa的颜色可能归因于表面铁和镁的浓度，而海绵状pa的金色可能是氟富集的结果。致密的hoe头的外缘由三层组成，它们是随着朝向表面的冷却速率增加而发展的。外部玻璃布边小于1厘米厚，包含少量的亚铬酸盐，橄榄石，斜长石和辉石。在玻璃状果皮内部是一个〜5 mm厚的过渡带，其特征在于淬火斜长石晶体和闪锌矿团簇的数量和尺寸增加。密集的蓝色玻璃状pahoehoe的内部大部分为结晶。晶体尺寸分布（CSD）理论表明斜长石，辉石和氧化物的形成和织构与致密Pahoehoe每一层中的冷却速率，生长速率（G）和成核速率（J）有关。与外部镶边相反，与均匀囊泡的海绵pahoehoe相比，晶体内部通常包含许多大的聚结囊泡。不良的囊泡状外部玻璃状镶边与囊泡状内部之间的谜团对比归因于密密麻麻的较低和较高的蒸气含量。与海绵状pa鱼相比，较高的密度，较低的挤出温度，脱气的外部玻璃镶边，内部发达的晶体内部以及密实的蓝色玻璃状的缺乏氟的表面表明，蓝色玻璃状的hoe子停滞了足够长的时间以溶解大量的蒸气。熔岩管系统在挤出之前。

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