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Formation and evolution of efflorescent halite speleothems beneath tepee structures in the Red Sea coastal evaporation settings, Jeddah, Saudi Arabia
Sedimentary Geology ( IF 2.7 ) Pub Date : 2020-12-30 , DOI: 10.1016/j.sedgeo.2020.105828
Mahmoud A. Aref , Ammar A. Mannaa

This study documents the occurrence of efflorescent halite speleothems of stalactites, columns, flowstones, stalagmites and popcorns beneath tepee structures in the Red Sea coastal sabkhas, desiccated halite pond and dykes of saltworks, Jeddah, Saudi Arabia. The study aims to interpret the formation and evolution of efflorescent halite speleothems due to the high relative humidity of the area. Field work and petrographic study revealed that the speleothems form from nighttime dissolution of the tepee halite crusts due to deliquescence at high relative humidity (DRH > 75%) and condensation of capillary vapor moisture at low relative humidity (RH < 75%). Dripping and flowing of deliquescent and condensed saline waters from the underside of the tepee structures by gravity and/or capillary forces are subjected to rapid evaporation in the daytime to deposit efflorescent halite speleothems. The evolution of the different types of efflorescent halite speleothems is controlled by the amount of saline waters droplets and flowing from deliquescence and condensation, air flow below tepee structures, evaporation rate and dynamic nature of the tepee crusts. The tepee structures are resulted from thermal expansion and contraction, and crystallization pressure exerted from growth of clear, early diagenetic and efflorescent halite crystals between primary chevrons, cornets and cubes of the crusts. In brief, the tepee structures form a barrier for escaping of the nighttime capillary vapor moisture to the atmosphere that condensed on the underside of the tepee structures. The daily capillary vapor diffusion, condensation of capillary moisture, deliquescence and evaporation are the factors that lead to precipitation of efflorescent halite speleothems beneath tepee structures in these particular settings of high humidity. The influence of rainfall or dew water for providing saline waters for the formation of the studied speleothems are of minor importance with regard to capillary vapor condensation and deliquescence, and in comparison to other studies described stalactites below tepee structures.



中文翻译:

沙特阿拉伯吉达红海沿岸蒸发环境下,圆锥形构造下的风化盐岩针状体形成和演化

这项研究记录了在沙特阿拉伯吉达的红海沿海萨布哈斯,干燥的盐岩池塘和盐厂的堤坝下,钟乳石,圆柱,流石,石笋和爆米花的风化岩盐斑发生。该研究旨在解释由于该地区较高的相对湿度而导致的风化盐岩鞘石的形成和演化。野外工作和岩石学研究表明,由于在高相对湿度(DRH> 75%)下潮解和在低相对湿度(RH <75%)下毛细蒸气湿气的凝结,使圆锥形盐岩地壳在夜间溶解而形成了蛇麻草。白天,重力和/或毛细作用力使圆锥形结构底部的潮解性水和冷凝盐水滴落和流动,使其迅速蒸发,从而沉积了风化的盐岩针状血丝。不同类型的风化盐岩针状花丝的形成由潮水和凝结的盐水滴和水流,圆锥形结构下方的气流,圆锥形结皮的蒸发速率和动态特性控制。圆锥形结构是由于热膨胀和收缩而产生的,结晶压力是由初等人字形,檐口和结壳之间的透明,早成岩和风化的盐岩晶体的生长产生的。简单来说,圆锥形结构形成用于将夜间毛细管蒸气湿气逸散到冷凝在圆锥形结构下侧的大气的屏障。在这些特殊的高湿度环境下,每天的毛细管蒸气扩散,毛细管水分凝结,潮解和蒸发是导致圆锥形结构下方的风化盐岩鞘脂沉淀的因素。对于毛细管蒸气凝结和潮解而言,降雨或露水对提供盐水以形成所研究的针脚类的作用的重要性不大,与其他在圆锥形结构下方描述的钟乳石相比,降雨或露水的影响次要。在这些特定的高湿度环境下,潮解和蒸发是导致风化岩盐岩鞘在沉淀物结构下方沉淀的因素。对于毛细管蒸气凝结和潮解而言,降雨或露水对提供盐水以形成所研究的针脚类的作用的重要性不大,与其他在圆锥形结构下方描述的钟乳石相比,降雨或露水的影响次要。在这些特定的高湿度环境下,潮解和蒸发是导致风化岩盐岩鞘在沉淀物结构下方沉淀的因素。对于毛细管蒸气凝结和潮解而言,降雨或露水对提供盐水以形成所研究的针脚类的作用的重要性不大,并且与其他在圆锥形结构下方描述的钟乳石相比,降雨或露水的影响次之。

更新日期:2020-12-30
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