【摘要】 <正> 自本世纪40年代以来,人们采用了酸类处理的方法来分解碳酸盐岩类型的岩石,使得牙形石分析工作获得了很大的进步。世界古生界大量碳酸盐岩中丰富的牙形石标本便是靠各种酸处理方法获得的。而处理的基本方式是将经过碎样的岩块(大约2cm左右)放入烧杯或塑料桶中浸泡、分解。人们把这种方法称浸泡法。采用10％浓度的醋酸来浸泡、分析碳酸盐岩以求获得牙形石化石的方法在美国古生物学家Collinson~1)(1963)的有关牙形石分析技术的专著中予以肯定(图1),并在以后的年代里为全世界的古生物学家更多还原

【Abstract】 For several decades, acetic acid or other organic acids have been used to dissolve limestones and other calcareous rocks for the recovery of conodont elements and other microfossils. The standard laboratory procedure has involved immersing the rocks in 10％ acetic acid in buckets or beakers, followed by wet sieving and heavy liquid and/or magnetic concentration （Collinson, 1963）. A flow diagram based on the method published by Collinson is shown in Fig. 1.In the present writer’s experience, conodont elements retrieved from the buckets are commonly broken, and the disaggregation of the rock is rather slow. In order to increase the rate of reaction and to minimize damage to the specimens, a tower apparatus （Fig. 2.）has been designed and constructed, operating under the principle of circulating the acid over the sample and protecting the freed specimens from damage that may be caused by contact with undissolved rocks.Fresh acid solution is placed in container A and is allowed to flow through a tube into the lower part of the tower. Within the tower is a nylon sieve （150 meshes or finer） on which the sample, crushed to fragments of about 1 cm, is supported. As the tower fills, the acid flows out of the top through the tubes to container B, from which it can be pumped back into container A for recycle through the apparatus. The flow at a rate of about ten litres per hour is sufficient, and the reaction can be further enhanced by inserting a stirrer into the upper part of the tower. When the sample has been dissolved, the acid may be removed from the tower through a tap （K₁） into container C. A circular door with a lid in the upper part of the tower allows removal of the nylon sieve, and the residue can be gently washed with water before concentration and examination.To exemplify the relative efficiency of this method, the writer has processed two 500g splits of the same sample （∈₃f-9） separately by the traditional. "Soak" method and by the tower apparatus method. Cold acetic acid was used. in both tests and the results are shown in Table 1. Only part of the soaked sample was dissolved in five days with very few good quality specimens recovered; however, in contrast with the "Soak" method, the sample in the tower was dissolved in two days with eight times as many well-preserved elements recovered.With this apparatus 0.5—1kg samples may be examined, but a larger tower could cope with larger amounts of rock samples. The rock layer on the sieve should not exceed 3 cm in thickness, and the procedure may be expanded for mass production by employing a series of towers, through which acid flows can be generated by a single pump.更多还原