Study of end-Paleozoic double-phased mass extinction : the G-L boundary and P-T boundary events

在4年的研究期间，我们在中国四川北方、日本九州中部和克罗地亚Velebit山脉进行了野外研究和室内地球化学分析。结果表明：（1）在G-L边界大灭绝前500万年的时间间隔内，首次发现了异常高的碳同位素比值正值。我们以九州的研究区域命名这一独特的全球性事件为“Kamura事件”。这意味着在超级海洋的初级生产力的增加，大量消耗大气中的CO2，温室效应的下降，并由此导致全球变冷。2）同时灭绝的瓜达卢佩浅滨海动物群组成的巨大的双壳类（Alatoconchidae），大型测试的fusulines和皱纹珊瑚被记录在特提斯和超级海洋泛地中海。这些“热带三人组”有着相同的光合共生习性 ...更多信息 3）Sr同位素比值在瓜达卢佩晚期达到中生代的最低值。这显然是与最大的海平面下降在浮游动物。这表明瓜达卢普末期事件与中二叠世晚期盘古大陆的初始裂解有关。4）华南P-T界线段以长英质（爆发）火山活动频繁为特征。地球化学和矿物学证据表明，该火山活动与地幔柱活动有关，从而部分支持了10多年前首席研究员提出的“地幔柱冬季”假说。由于这些结果包含了一些新的发现和第一视角，我们已经在国际科学期刊上发表了29篇文章，出版了2本书，并在国际会议上进行了6次口头报告，包括3次主题演讲。少

During the 4 years of research under the support of this grant-in-aid, we conducted field studies in the northern Sichuan in China, central Kyushu in Japan, and the Velebit mountains in Croatia, and in door geochemical analyses. These led the following results and conclusions.1) An unusually high positive values of carbon isotope ratio was detected for the first time from a 5 million years interval immediately before the G-L boundary mass extinction. We named this unique event of a global context the "Kamura event" after the study area in Kyushu. This implies the increase in primary productivity in the superocean, mass consumption of atmospheric C02, decline in greenhouse effect, and resultant global cooling.2) The simultaneous extinction of the Guadalupian shallow marina fauna composed of gigantic bivalves (Alatoconchidae), large-tested fusulines and rugose corals was documented both in Tethys and the superocean Panthalassa. These "tropical trio" shared the same habit of photosymbiosi … More s with algae/bacteria under oligtrophic environments, and they were terminated probably by cooling through the collapse of photosymbiosis.3) We confirmed that the Sr-isotope ratio reached the minimum of the Phanerozoic in the late Guadalupian. This apparently coincided with the greatest sea-level drop in the Phanerozooic. These indicate the end-Guadalupian event was related to the initial Pangean breakup in the late Middle Permian.4) We found that the P-T boundary interval in South China is characterized by frequent activity of felsic (explosive) volcanism. Geochemical and mineralogical lines of evidence suggest that this volcanism was related to mantle plume activity.The above-listed results partly prove thus positively support the "Plume Winter" scenario that the head investigator proposed more than 10 years ago. As the results contain several new finds and the first perspectives, we already reported in 29 articles in international scientific journals, 2 books, and 6 oral presentations at international meetings including 3 keynote speeches. Less