摘要
福建西部早古生代杂砂岩属富石英杂砂岩类。稳定碎屑石英的高含量和不稳定碎屑长石、岩屑的强烈贫化,表现了沉积物具再旋回特点。很高的SiO_2含量及CaO、Na_2O的贫化,并以低的Fe_2O_3+MgO、Al_2O_3/SiO_2、TiO_2和高的变化极大的K_2O/Na_2O、Al_2O_3/(CaO+Na_2O)与被动大陆边缘沉积的杂砂岩相类似。稀土元素模式及其参数特征相似于现代的和古代的被动大陆边缘环境沉积的杂砂岩。分析表明,本套杂砂岩的源岩是以沉积岩、浅变质岩为主和中—酸性火成岩混合组成,所处的大地构造背景为构造上不活动的被动大陆边缘或弧后盆地环境。
The study of petrology, major element, geochemistry and REE patterns shows that graywacke in western Fujian belongs to typical quartz-rich graywacke. The high content of stable clastic quartz and strong depletion of unstable clastic feldspar and rock fragments suggest the recyclicity of sediments. The major element geochemical analysis reveals a very high SiO_2 content and depletion of CaO and Na_20. It is similar to graywacke deposited at the passive continental margin in low ratios of Fe_2O_3+MgO and Al_2O_3/SiO_2 and a low TiO_2 content and greatly varied high K_2O/Na_2O and Al_2O_3/(CaO+Na_2O). The REE patterns and characteristics of REE parameters are similar to those of the graywacke deposited at the modern and ancient passive continental margin.A series of synthetic analyses show that the protolith of the early Paleozoic graywacke in western Fujian is composed of a mixture of mainly sedimentry rocks and low-grade metamorphic rocks and intermediate-acid igneous rocks. The tectonic setting is the tectonically inactive passive continental margin or the back-arc basin.
出处
《地质论评》
CAS
CSCD
北大核心
1989年第6期501-511,共11页
Geological Review
