摘要
晚泥盆世榴江组硅质岩仅分布于深水盆地相中,受同沉积深大断裂活动控制,主要由微晶石英组成,含大量放射虫、竹节石、颗石藻及翼足类等深水浮游生物;化学成分富SiO2,贫Al2O3和TiO2,K2O/Na2O大于1;稀土元素分析表现出Ce负异常、稀土总量低和稍富重稀土的热水沉积特点;δ18O值平均为23.9‰,低于泥盆纪平均值;并于同层位内发现高温长石和凝灰物质等海底火山活动证据,表明该硅质岩是经热水沉积及生物化学沉积形成的原生硅质岩,SiO2主要来自深部,由海底火山活动提供。
The distribution of the silicalites of liujiang formation, Upper Devonian is limited in the basin facies and controlled by the activities of the syndepositional deep fault.The silicalites consist of microcrystalline quartzs,in which there are a large quartity of deep-water planktons,for example, Radiolarias, tentaculitid, Coccolithus and Pterypode, The chemical analysis of the silicalites shows that SiO_2 is rich,Al_2O_3 and TiO_2 are poor, and that K_2O is more than Na_2O. REE analysis is characteristed by negative anomaly of Ce, Low total amounts of REE and more heavy REE than that of other types of sedimentary rocks. The value of δ^(18)O in the silicalites is 23.9‰, which is lower than the average value of the Devonian silicalites in the world. The high temperature feldspar and tuffaceous texture are found as the evidence of the sea-floor volcanic activities.Above mentioned charactristics show that the silicalites are formed by the hydrothermal and organic chemical depositions and that SiO_2 is principally offered by the sea-floor volcanic activities.
出处
《矿物岩石》
CAS
CSCD
1989年第4期22-29,共8页
Mineralogy and Petrology
基金
国家自然科学基金
