Experiments in connection with Salt Domes
Experiments in connection with Salt Domes
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与盐丘有关的实验
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通讯作者：
P. Kuenen
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作者：
B. Escher;P. Kuenen
讨论了德国鲁马尼亚、德克萨斯州、路易斯安那州、科罗拉多州和犹他州关于盐丘起源的不同理论。在鲁马尼亚，盐存在于“底辟”背斜的核心中。盐丘的存在表明，盐分仍在向上推进。在德国，盐区显示出轻微的褶皱，但盐本身是密集褶皱的。Lachmann-Arrhenius-Harbort理论解释了盐丘的均衡作用，结合了较低的比重和比覆盖层更大的可塑性。这一理论遭到了斯蒂尔的反对，他解释了中生代褶皱形成的盐丘。后一种理论显然在美国获得了对德克萨斯州和路易斯安那州盐丘的解释的青睐，尽管在那里没有遇到折叠的迹象。进行了两个系列的实验。第一系列是为了确定德国盐矿中观察到的错综复杂的褶皱的三维形态，尤其是围绕垂直轴的褶皱非常显著。此外，它的目的是找出，通过利用可以被比作均衡的力，是否可以人为地产生类似的褶皱。当使用相同塑性的层时，出现规则的一致褶皱(Ep。I，1)。当不同塑性的层相互交替时，出现了较小的、复杂的、不协调的褶皱，叠加在较大的褶皱上，对应于前面的实验(Exp。I，2-7)。值得注意的是，在垂直压力场中，由于塑料和塑料较少的材料之间的粘度不同，较少塑性的材料与运动方向成直角的裂缝被塑料材料填满。预计盐田也会有类似的租金。2d系列的实验是在反压等于每表面单位初始压力的一半的情况下进行的。进行这些实验的原因是在第一个系列中出现了空隙。在自然界中，由于覆盖层的重量，在盐的上升过程中也存在相当大的反压力。在塑性相同的材料中，形成了显著的褶皱，在垂直截面上呈M型(Exp。1、系列II)。实验6，系列II表明，随着一系列较厚的层的出现，顶层可能会先于下层移动。这样，两个M形就形成了一个在另一个之上。实验3和4是用熔点均匀的白色石蜡制成的，其中放置了一排水平的垂直柱子，分成几层，以便能够重建石蜡的流线。在这里，可以看到石蜡与压缩装置的铁壁之间的摩擦对石蜡的运动产生重要影响。实验的主要结果是，在德国盐丘观察到的所有褶皱形状都可以用拉赫曼的理论完全解释，也就是说，柱状物质中特定较轻的盐被均衡地向上挤压。然而，这本身并不排除切向压力可能是已知现象的部分或全部原因的可能性。1927年9月3日，资深作者在Schweiz矿物学部的一次会议上，就第一系列实验在巴勒做了一次演讲。Naturforschende Gesellschaft(Bibl.19)在代尔夫特举行的地质部年度会议上。1928年3月，尼德兰·恩科洛尼安的米扬布乌昆迪克·基诺斯查普·沃尔。
The different theories concerning the origin of Salt Domes in Roumania, Germany, Texas, Louisiana, Colorado and Utah are discussed. In Roumania the salt occurs in cores of “Diapir” anticlines. The existance of hills of salt indicates, that the salt is still pushing upwards. In Germany the salt district shows slight folding but the salt itself is intensively folded. The theory of Lachmann-Arrhenius-Harbort explains the salt domes by isostasy combined with a lower specific gravity and greater plasticity of the salt than of the covering layers. This theory is opposed by Stille, who accounts for the salt domes by mesozoic folding. The latter theory has apparently gained preference in America for the explanation of the Salt Domes in Texas and Louisiana, although no indications of folding are met with there. Two series of experiments were carried out. Those of the first series were made to determine the form in three dimensions of the intricate folding, observed in the German salt mines and of which the folds round vertical axes in particular are very remarkable. Further it was the aim to find out if, by making use of forces, which may be compared to isostasy, similar folds could be artificially produced. When using layers of identical plasticity, regular congruous folds occurred (exp. I, 1). When layers of different plasticity alternated with eachother, smaller complicated, dis-harmonious folds arose, superimposed upon larger ones, corresponding to those of the preceeding experiment (exp. I, 2—7). It is important to note that in the field of vertical pressure, by difference in the viscosity between plastic and less plastic material, fissures were torn in the less plastic material, at right angles to the direction of movement, which were filled up by the plastic material. Similar rents may be expected in the salt fields. The experiments of the 2d series were made with a counter pressure equal to half the initial pressure per surface unit. The reason for making these experiments was that in the first series air-spaces occured. In nature, also, a considerable counter-pressure exists, during the rising of the salt in consequence of the weight of the covering layers. Remarkable folds were formed, which, in material of identical plasticity, showed an M-form in vertical section (exp. 1, series II). Exp. 6, series II showed that with a thick series of layers the top layers may begin to move before the lower ones. In this way two M-shapes originated one above the other. Exp. 3 and 4 were made with white paraffin of uniform melting point in which were placed a horizontal row of vertical pillars divided into layers, so as to be able to reconstruct the stream lines of the paraffin. Here the friction between the paraffin and the iron walls of the compression apparatus were seen to exercise an important influence upon the movement of the paraffin. The principle result of the experiments is that all shapes of folds, observed in the German salt domes, can be completely explained by Lachmann’s theory, that is by the isostatic pressing up of the specifically lighter salt in pillar-like masses. This alone, however, does not exclude the possibility that tangential pressure may be partially or entirely responsible for the known phenomena. The senior author gave a lecture on the first series of experiments at Bâle on September 3, 1927, at a meeting of the Mineralogical section of the Schweiz. Naturforschende Gesellschaft (bibl. 19) and at Delft in the annual meeting of the geological section of the Geol. Mijnbouwkundig Genootschap voor Nederland en Kolonien in March 1928.