X線CTスキャンの活用法“アブダビ海上コアサンプル中での白亜紀セノマニアンのルディスト化石（厚歯二枚貝）の発見“

抄録

Rudists are a group of strange shaped marine bivalves living in the Tethys Ocean from the Late Jurassic to the Late Cretaceous. They have various shapes ranging from box, tube, to ring shapes. In the Middle East, many carbonate oil fields are composed of rudists. But less attention has been paid to the taxonomy, paleo-ecology and sedimentology of rudists until now. It is important to capture three-dimensional geometry of rudist for understanding them mentioned above, although it is difficult to see three-dimensional geometry of the rudists in slab cores which just indicate partial sections at cutting surfaces. In this study, X-ray CT scan technology is using for delineating the above of rudists from cores as nondestructive approach. Scanning direction is also important to obtain better resolution for identifying taxonomy to identify rudist “species”. Our trial revealed that most of vertical CT images show probably software-based “ring artifact” which may be created by image correction process. This artifact may be a result of large difference of relative density between adjacent objects such as air and very hard tissue like rudist hard shells. Therefore, our trial suggests that transection direction (lateral direction) is the recommended scanning direction for obtaining better resolution. We are continuing study to identify “species” using 3D view software.

Currently, the identification of rudist is completely relaying on human eyes. But it may be possible to use AI for rudist recognition on cores although it requires further development of techniques. rudist fossils can be identified even in the general X-ray CT scan as “Digital core” for the measurement of reservoir properties. Therefore, the development of image recognition for rudist could be a routine work for rudist recognition with AI in Cretaceous core in the future.