报告人：崔胜

　　报告题目：Thermal maturity of East Asian fossil eggs

　　合作导师：徐星

　　评审委员会主席：周忠和

　　委员：徐星、王敏、王原、张驰

　　时间：2023年7月17日（星期一）15:30

　　地点：古脊椎所9楼会议室

　　内容简介： 

　　East Asia has been an important region for fossil egg research due to its rich record of fossil eggs. One of the interesting things of East Asian eggshells is that they show diverse colors depending on fossil localities. Generally, eggshells in Korea and Japan and coastal part of China (e.g. Zhejiang, Guangdong) are dark colored whereas eggshells in inland China (e.g. Hubei, Gansu) are more lighter (light brown), and eggshells in Mongolia are pale brown to nearly white in color. To find the reason behind the color variation in East Asian fossil eggs, I analyzed spatiotemporally diverse egg fossil with Raman spectroscopy to collect maximum paleogeotemperature data from the eggshells. The Raman data showed that dark-colored coastal China, Korea, and Japanese eggshells yield clear disordered and graphite bands in their Raman spectra whereas eggshells from inland parts of China and Mongolia do not show any sign of thermal alteration. The eggshell colors in East Asia are most probably related with the thermal maturity of fossil-bearing sedimentary basins, and this interpretation is additionally supported by other organic geological evidence such as vitrinite reflectance and illite crystallinity. The results imply that microstructural deterioration (e.g. recrystallization), which is often seen from fossil eggs is not entirely caused by geothermal heat. In addition, the results of this study may be used for correct interpretation of isotopic data, such as clumped-isotope-paleothermometry, which is vulnerable to geothermal heat. In addition, the results may be useful for diverse subfields in molecular paleontology as well.

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