Displacive halite crystals in fine-grained sediments are a common feature of evaporitic sequences worldwide. The crystal habit of halite precipitated from pure aqueous solution under laboratory conditions is a cube: equal side lengths (a = b = c) and rectangular angles (ab = bc = ac = 90°). Crystals with deformed-looking shape appear in mudstone of Permian evaporites of the Eastern Alps. They expose platy, rod-like, parallelepiped-like or rhomb-like shapes. The aim of the study was to explain the origin of these shapes. Samples were taken in the Altaussee, Berchtesgaden, and Hallstatt mines. Representative mudstone samples were scanned by high-resolution X-ray CT, and halite shapes were restored by 3D software. Additionally, 327 euhedral halite crystals were dissected from mudstone and subjected to individual shape analysis. Their sizes range from 3 to 30 mm in thirteen specimens. Crystals are compact, but a slightly platy preference prevails in all samples. Approximately 80% of all objects expose angles > 1° deviating from the right angle, but only ∼ 15% contain angles > 20°. The maximum deviation from the right angle was ca. 33°. Most objects combine a platy shape (a ≈ b ≠ c) with only one angle deviating from the right angle (2× 90°). The acute angle is preferably oriented parallel to the layering. We interpret a primary rectangular crystal growth to platy shapes in the mudstone (reduced fluid circulation). The displacive halite crystals subsequently deformed during compaction of the mudstone. Halite in deformed shapes was replaced by datable polyhalite ca. 15 My after deposition, which rules out deformation during Alpine tectonics.

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变形的变形盐岩晶体：成岩作用还是构造起源？

细粒沉积物中的位移性盐岩晶体是全世界蒸发序列的共同特征。在实验室条件下从纯水溶液中沉淀出的盐酸盐的晶体习性是一个立方体：边长相等（a = b = c）和直角（ab = bc = ac = 90°）。外观变形的晶体出现在东阿尔卑斯山的二叠纪蒸发岩的泥岩中。它们暴露出板状，棒状，平行六面体状或菱形状。该研究的目的是解释这些形状的起源。样品是在Altaussee，Berchtesgaden和Hallstatt矿中采集的。通过高分辨率的X射线CT扫描代表性的泥岩样品，并通过3D软件恢复盐岩形状。此外，从泥岩中分离出327块全卤石晶体，并进行了单独的形状分析。在13个标本中，它们的大小从3到30 mm不等。晶体是致密的，但在所有样品中普遍偏板状。所有物体中大约80％的角度偏离直角的角度大于1°，但只有约15％的角度大于20°。与直角的最大偏差为。33°。大多数对象将板状形状（a≈b≠c）组合在一起，只有一个角度偏离直角（2×90°）。锐角优选平行于层定向。我们将原始的矩形晶体解释为泥岩中的板状形状（减少了流体循环）。置换的盐岩晶体随后在泥岩的压实过程中变形。变形形状的卤石被大约为Datable的多卤石所代替。15我的沉积后，排除了高山构造期间的变形。