黔北黑色岩系的岩石地球化学特征和成因  

GENESIS AND PETROGEOCHEMISTRY CHARACTERISTICS OF LOWER CAMBRIAN BLACK SHALE SERIES IN NORTHERN GUIZHOU

作　　者：杨剑[1] 易发成[1] 侯兰杰[1] 

机构地区：[1]西南科技大学,四川绵阳621002

出　　处：《矿物学报》2004年第3期285-289,共5页Acta Mineralogica Sinica

基　　金：四川省教育厅资助项目

摘　　要：黔北下寒武统黑色岩系主要由硅质岩、磷块岩、多元素富集层、黑色页岩等组成。采用X射线粉末衍射分析和扫描电镜分析研究了各岩类的矿物成分特征,重点进行了微量元素地球化学研究,黑色岩系微量元素总量在金属富集层之钼矿层达到峰值,显示出在剖面上从下到上先渐次增加后又有所回落的趋势。黑色岩系中Ba、As、Sb等元素的浓集系数普遍较高,高于有关热水沉积物的统计数据,反映出较强的热水沉积作用的特征。各岩类U/Th比值均大于1,钼矿层甚至达119,表明受到较强的热液活动的影响。δU=1 73～1 99>1,表现为缺氧沉积环境。在Zn Ni Co三元图中,也显示了热水沉积的特点。可见,黑色岩系形成于缺氧滞流海盆,热液活动提供了丰富的物质来源。The black shale series in northern Guizhou consist mainly of silicate, phosphate, metal-rich shale and black shale. This paper deals with the compositional characteristics of minerals in the black shale series using X-ray diffraction analysis and scanning-electron microscope analysis, and the trace element geochemistry of the black shale series has been systematically studied. The trace element contents of the black shale series reach their peak value in the Mo ore bed of metal-rich shales, and tend to decrease upwards and downwards, which may be connected with an abnormal seawater sedimentary process. The contents of Ba, As, Sb in the black shale series are higher than those of hydrothermal sediments. In the black shale series, U/Th>1, δU >1. All the trace element geochemical characteristics of the black shale series show that the black shale series are a product of submarine exhalative sedimentation, indicating that the black shale series were deposited in an anoxic sea environment.

关 键 词：黑色岩系 岩石地球化学 缺氧环境 热液沉积 

分 类 号：P581[天文地球—岩石学] P588.22[天文地球—地质学]