广西乐业泥盆系—石炭系沉积碳酸盐岩脉及地震事件沉积的新发现

New Approach on Devonian—Carboniferous Carbonate Neptunian Dikes and Earthquake Events in Leye,Guangxi

广西右江盆地发育多个孤立碳酸盐岩台地,在各台地边缘广泛发育同沉积断层及沉积碳酸盐岩脉,常常发育地震事件记录。在广西乐业台地边缘上泥盆统融县组鲕粒灰岩、藻粘结灰岩等地层中新识别出多条晚泥盆世沉积灰岩脉:玛瑙纹状灰岩脉、白云岩脉、微晶灰岩脉及藻灰岩脉等,新识别出早石炭世海百合茎灰岩脉(内部结构呈高密度颗粒流状新类型),同时观察到同沉积断层及同生角砾岩、层内断错及原地震裂岩等,为沉积碳酸盐岩脉的成因提供新的证据,同时表明在乐业台地边缘,至少有两次同沉积正断层的活动,一次发生在晚泥盆世,诱发了脉及围岩均为晚泥盆世融县期的沉积碳酸盐岩脉、层内断错及原地震裂岩;一次发生在早石炭世,诱发的脉为早石炭世尧云岭期,围岩为上泥盆统融县组的沉积灰岩脉及伴生角砾岩。展示了在广西右江盆地发生张裂背景下,乐业台地边缘同沉积正断层活动,诱发地震事件,同时伴生张裂隙,即沉积灰岩脉的构造-沉积过程,是广西右江盆地在晚古生代伸展过程的历史记录。

A lot of isolated carbonate platforms occurred in the Late Palaeozoic Youjiang basin, Guangxi-- Guizhou. Carbonate neptunian dike and synsedimentary normal faults occurred commonly on their margins. Paleoearthquakes are recorded by synsedimentary normal faults. On the margin of the leye platform, Guangxi, Late Devonian carbonate neptunian dike are discovered in the ooid grainstones and algal bindstones of the Upper Devonian Rongxian Fro. Those dikes are： agate laminated limestone dike, dolomite dike, microcrystal limestone dike, and algal bindstone dike etc. Early Carboniferous crinoidal grainstone dikes are also discovered there. Synsedimentary normal faults and their breccia and in situ earthquake shatter breccia are developed there, too. Thus provide new evidences for how the carbonate neptunian dike formed. In the Leye platform margin, there are at least two times normal fault moving： once occurred in Late Devonian and resulted in Late Devonian carbonate neptunian dikes in Late Devonian surrounding rocks; another occurred in Early Carboniferous and resulted in Carboniferous carbonate neptunian dikes and fault breccia in Late Devonian surrounding rocks. All the observations suggest that the synsedimentary normal faults on the Leye platform margin move and result in earthquake and carbonate neptunian dikes, based on the intense structure stretch history of the Youjiang basin in late Palaeozoic. background. Such structure -deposit process records the