摘要
荆山玉是湖北省保康县新发现的一个玉石品种,形成于大陆边缘—洋盆区过渡带的热水沉积环境,为晚震旦世—早寒武世灯影组的一种硅质角砾岩:原地震碎角砾岩,由角砾和胶结物二部分构成,角砾局部可拼接;角砾成分为早期硅质岩碎裂产物,胶结物除早期硅质岩碎裂产物外,还有少量后期充填的石英、铁质等,受角砾、胶结物颗粒大小、裂隙发育程度不同的影响,后期热液改造程度不同,角砾和胶结物化学成分存在一定的差异,色调与铁质有关。荆山玉的形成主要经历了三个阶段的演化:第一阶段,低温150~225℃、弱氧化—弱还原条件下热水成因的硅质岩形成;第二阶段,热力膨胀外力作用下,硅质岩局部原地震碎形成硅质角砾岩,热水温度243~340℃,富氧氧化—贫氧过渡环境,红褐色的Fe 3+在胶结物、裂隙中富集;第三阶段,热水温度116~127℃、缺氧还原条件,黄色的Fe 2+在胶结物、裂隙中富集。
Jingshan jade is a newly kind of jade discovered in Baokang County,Hubei Province.It was formed in the hot water sedimentary environment of the transitional zone between continental margin and ocean basin.It is a kind of siliceous breccia in Dengying Formation from late Sinian to Early Cambrian.It is composed of two parts of breccia and cement,and the breccia can be spliced locally.The breccia is the product of early siliceous rock fragmentation,and the cement can be divided into early siliceous rock.In addition to the rock fragmentation products,there are a small amount of quartz and iron filled in the later stage.Influenced by the size of breccia and cement particles and the development degree of fractures,the later stage of hydrothermal transformation is different,and the chemical composition of breccia and cement is different to some extent.The color is related to iron.The formation of Jingshan jade mainly experienced three stages of evolution.The first stage:the formation of siliceous rock caused by hot water under the condition of low temperature 150~225℃,weak oxidation-weak reduction.The second stage:under the effect of thermal expansion,the siliceous rock was locally crushed in situ to form siliceous breccia;the hot water temperature was 243~340℃,the transition environment of oxygen rich oxidation poor oxygen;the reddish brown Fe 3+was in cement and fracture The third stage:under the condition of the temperature of hot water was 116~127℃,and anoxic reduction conditions,the Yellow Fe 2+was enriched in cement and fracture.
作者
向祥辉
张维江
李立锋
牛志勇
李丽华
王家杰
王球
Xiang Xianghui;Zhang Weijiang;Li Lifeng;Niu Zhiyong;Li Lihua;Wang Jiajie;Wang Qiu(Eighth Geological Brigade of Hubei Geological Bureau,Xiangyang,Hubei 441002)
出处
《资源环境与工程》
2020年第1期24-31,共8页
Resources Environment & Engineering
关键词
荆山玉
地质特征
地球化学特征
成因分析
保康县
刘家坪村
Jingshan jade
geological characteristics
geochemical characteristics
Baokang County
Liujiaping village
