浙江多色青田石岩石地球化学特征及成因

多色青田石是浙江青田石中的一个重要品种,具颜色丰富、纹理多变的特点。通过岩相学观察、X射线粉晶衍射物相分析、全岩主量及微量元素和同位素地球化学分析,对多色青田石的岩石学特征、矿物成分、类型划分进行详细研究,并论证了多色青田石的成矿物质、成矿流体来源及成因。研究表明:多色青田石按主要组成矿物划分属于叶蜡石型青田石和绢云母型青田石;其颜色主要与组成矿物中Fe、Ti、Cr、Mn致色元素的类型和含量有关,其次与赤铁矿(褐铁矿)浸染组成矿物的微晶间隙和充填微裂隙有关。多色青田石的成矿母岩为中酸性火山岩,成矿流体来源与大气降水有关。多色青田石主要由早期充填成因的叶蜡石矿物和晚期由中低温热液蚀变改造早期叶蜡石形成的绢云母矿物构成,是多期多阶段热液蚀变交代成矿作用的产物,多色青田石中常保留高温矿物红柱石。

Mineral Geochemistry Characteristics and Genesis of the Multicolor Qingtian Stone from Zhejiang Province

Multicolor Qingtian stone is one kind of Qingtian stones from Zhejiang province,shows all kinds of colors and varied textures.In this study,based on the analysis of the petrography,X-ray powder crystal diffraction phase,whole rock major,trace elements and isotope geochemistry for the multicolor Qingtian stone,we have verified the petrologic features,mineral compositions and type divisions,and discussed the ore-forming materials,ore-forming fluids and genesis.Studies have shown that the multicolor Qingtian stone belongs to pyrophyllite-type Qingtian stone and sericite-type Qingtian stone according to the main mineral compositions.The color of the multicolor Qingtian stone is mainly related to the content of colored elements(e.g.Fe,Ti,Cr and Mn),and has a little of relationship with mineral microcrystalline particles and micro-cracks of hematite(limonite)impregnation of constituent minerals.The ore-forming materials of the multicolor Qingtian stone sourced from medium-acid volcanic rock,and ore-forming fluids sourced from meteoric waters.The multicolor Qingtian stone is mainly composed of filling-genesis pyrophyllite in the early stage and sericite that formed by medium-low temperature hydrothermal alteration on the filling-genesis pyrophyllite in the late stage.It derived from multi-period and multi-stage of hydrothermal alteration metasomatism.Multicolor Qingtian stone often retains high temperature mineral andalusite.