广西丹池盆地F-F界线事件沉积及成因分析

Event Deposits near F-F Boundary in Nandan-Hechi Basin and Their Origin

广西丹池(南丹—河池)盆地内部在上泥盆统弗拉斯阶与法门阶分界线上普遍发育事件沉积作用,自台地边缘到台内裂陷槽盆地事件沉积分为碎屑流、颗粒流和浊流,沉积岩石分别为砾屑灰岩、含砾砂屑灰岩、递变层砂屑灰岩等。该事件沉积具有等时性、成因相关性和广布性。事件沉积绝大部分位于linguiformis带和triangularis带之间。这些事件沉积可以和广西横县六景、桂林杨堤、德保都安、武宣南峒、象州香田、崇左那艺、上林云攀以及比利时的Hony剖面、美国内华达的Devil sGate剖面、摩洛哥的Atrous剖面、南乌拉尔、俄罗斯西伯利亚东北部的Fore-Kolyma、波兰—摩拉维亚盆地南部(Holy Cross山脉,Cracow和Brno地区)法门阶底部的浊积岩和角砾岩对比。如此广泛的全球性分布的等时性的事件沉积可以和巨大的外行星撞击地球而引起的全球性海啸相联系。

A suite of event deposits, isochronous and interrelated in origin, are widely found near the Frasnian- Famennian boundary in Nandan-Hechi Basin of Guangxi, South China. From the platform margin to the inter-platform rift trough, the event deposits are divided into debris, grained flow and turbidity deposits. They are mainly composed of rudstone, calcirudite, massive homogenites and turbidites. They occur between linguiformis and triangularis Zone and can be correlated in the stratohorizon to Liujing section of Hengxian, Yangdi of Guilin, Du＇an of Debao, Nandong of Wuxuan, Xiangtian of Xiangzhou, Nayi of Chongzuo , Yunpan of Shanglin and to the turbidite in the bottom of the Lower in Hony railroad cut of Belgium, Devils Gate of Nevada, USA, Atrous of Morocco, South Urals and Fore-Kolyma of north- eastern Siberia of Russia, and to erosional discontinuities and brecciation in the Frasnian-Famennian boundary in South Polish-Moravian shelf. It is assumed that the event deposits could be caused by a violent tsunami related to bolide impacts into ocean.