The Kellwasser events in the Upper Devonian Frasnian to Famennian transition in the Toc Tat Formation, northern Vietnam
The Kellwasser events in the Upper Devonian Frasnian to Famennian transition in the Toc Tat Formation, northern Vietnam
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DOI：
10.1111/iar.12281
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发表时间：
2018-11
期刊：
影响因子：
1.5
通讯作者：
T. Komatsu;Ryota Urakawa;T. Inada;K. Yamauchi;T. Maekawa;R. Takashima;M. Williams;Phong Nguyen;H. D. Doan;Minh T. Nguyen;S. Niko;G. Tanaka;T. Yamaguchi
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文献类型：
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作者：
T. Komatsu;Ryota Urakawa;T. Inada;K. Yamauchi;T. Maekawa;R. Takashima;M. Williams;Phong Nguyen;H. D. Doan;Minh T. Nguyen;S. Niko;G. Tanaka;T. Yamaguchi
越南北方同货车区Si Phai Pass地区上泥盆统Toc达特组碳酸盐岩沉积于碳酸盐岩台地、斜坡和盆地环境。这些碳酸盐岩产出丰富的牙形刺，指示Palmatolepis nasuta，Pa。linguiformis和Pa. frasnian-Famennian阶段的边界被确定为第一次出现的Pa。三角肌两个正的碳同位素偏移被确认，低偏移峰值在低到中Pa的间隔。nasuta区，而上游览高峰正好在当地弗拉斯阶-法门阶边界之上。根据生物地层学，这些漂移相当于下和上Kellwasser事件。在当地，tentaculitoid类群（Nowakia，Styliolina，Homoctenus和Metastyliolina？）在Pa的间隔中是丰富的。nasuta带，但在下Kellwasser事件之前，丰度急剧下降，只有两个分类群幸存到法门阶。
Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian.