缅甸琥珀内含物形态结构在X射线下的可辨识性

【目的】产自缅甸北部胡康河谷的缅甸琥珀形成于白垩纪中期。其艺术价值很高,同时其内含物的生物多样性程度也很高,故其科学价值也不可估量。显微CT能够提供化石(琥珀)内部解剖结构的高分辨率断层图像,故该方法日渐成为目前琥珀研究中的常用方法之一。然而在可见光下可见的琥珀内的生物结构,在X射线下却有不同的结果,这与现生研究材料在显微CT下的表现非常不同。本研究对产自胡康河谷的9块缅甸琥珀进行显微CT检测,试图对这个特殊的现象进行较为系统的解读。【方法】利用数码相机(Nikon 5200D)拍摄琥珀照片,并用Helicon Focus 5.3软件合成。通过显微CT技术扫描琥珀和计算机断层重建技术重建出缅甸琥珀内含物的三维结构形态。【结果】显微CT检测结果主要分为3种:完全无衬度、部分结构有衬度和整体结构有较好衬度。本研究对有较好衬度的琥珀内含物进行了三维重建,展示了琥珀内含物的外部和内部三维结构。【结论】琥珀内含物的可见光成像和X射线成像不存在一一对应关系,其原因和琥珀保存的好坏以及琥珀的密度差、琥珀围岩之间的对比度差异有关。琥珀形成和埋藏过程中的物理和化学变化非常复杂,其机理的探究也更为复杂和困难,本文对这个现象的主要类型做了较为初步的阐述,后续研究需要更为全面的选样和更为严格的实验设计才能够最终解决这个埋藏学上的难题。

Morphological identifiability of Burmese amber inclusions under X-rays

Aim] Burmese ambers from the Hukawng Valley of North Myanmar are estimated to be formed in the middle Cretaceous.Not only did these ambers have very high artistic value,but also their inclusions had high biodiversity and immeasurable scientific value.Micro-CT can provide high-resolution tomographic image of internal anatomy from fossil (amber).In this case,Micro-CT is becoming one of the common methods of amber study.However,the biological structures within the amber visible from microscopy may demonstrate very different results under X-rays.On the contrary,the extant materials could provide similar performance in the detection under microscopy and Micro-CT.This study aims to ascertain this particular phenomenon based on nine Burmese amber samples from the Hukawang Valley.Methods] Photographs were taken using a Nikon 5200D digital camera and processed with Helicon Focus 5.3 software.Nine Burmese amber samples were scanned by micro-CT.The Burmese amber inclusions were reconstructed by computer tomography reconstruction technologys.Results] The MicroCT results were mainly divided into three types:no contrast completely,contrast in partial structure and good contrast in most structures.The external and internal structures with visible contrast were reconstructed based on the CT data obtained from Burmese ambers.Conclusion] There is not always good relationship between visible light imaging and X-ray imaging of amber inclusions.This phenomenon is probably related to the preservation of the amber,amber density difference,and the difference in contrast between the surroundings of amber.The physical and chemical changes during the process of amber formation and burial are very complex.The mechanisms would be more complex and difficult to be inferred.Here we preliminarily illustrated the main types of this phenomenon.More comprehensive sampling and more strict experimental design in the follow-up studies may finally solve this problem on taphonomy.