Petrochemical eigenvalues and diagrams for the identification of metamorphic rocks’ protolith, taking the host rocks of Dashuigou tellurium deposit in China as an example

• 作者: OA Jianzhao Yin Shoupu Xiang Yuhong Chao Yuhan Yin Hongyun Shi .College of Earth Sciences Jilin University .Silvercorp Metals Inc .Engineering Geology Brigade of Jiangxi Bureau of Geology .Xuchang Electrical Vocational College .Orient Resources Ltd
• 来源期刊: 地球化学学报(英文）
• 学科: 地球科学
• 年，卷（期）: 2023,（1）
• 页码范围: 103-124
• 页数: 22页
• 语种: 中文

摘要

The Dashuigou tellurium deposit is the world's only known independent tellurium deposit.By restoring metamorphic rocks' protolith,we seek to understand not only the development and evolution trajectory of the region but also the origin of the relevant deposits.While there are many ways to restore metamorphic rocks' protolith,we take the host metamorphic rocks of Dashuigou tellurium deposit and leverage various petrochemical eigenvalues and related diagrams previously proposed to reveal the deposit's host metamorphic rocks' protolith.The petrochemical eigenvalues include molecular number,Niggli's value,REE parity ratio,CaO/Al2O3 ratio,Fe3+/(Fe3+-+Fe2+) ratio,chondrite-normalized REE value,logarithmic REE value,various REE eigenvalues including scandium,Eu/Sm ratio,total REE amount,light and heavy REEs,δEu,Eu anomaly,Sm/Nd ratio,and silicon isotopeδ30SiNBS-29‰,etc.The petrochemical plots include ACMs,100 mg-c-（al+alk）,SiO2-（Na2O+K2O）,（al+fm）-（c+alk） versus Si,FeO+Fe2O3+TiO)-Al2O3-MgO,c-mg,Al2O3-（Na2O+K2O）,chondrite-normalized REE model,La/Yb-REE,and Sm/Nd ratio,etc.On the basis of these comprehensive analyses,the following conclusions are drawn,starting from the many mantle-derived types of basalt developed in the study area of different geological ages,combined with the previously published research results on the deposit s fluid inclusions and sulfur and lead isotopes.The deposit is formed by mantle degassing in the form of a mantle plume in the late Yanshanian orogeny.The degassed fluids are rich in nano-sc ale substances including Fe,Te,S,As,Bi,Au,Se,H2,CO2,N2,H2O,and CH4,which are enriched by nano-effect,and then rise to a certain part of the crust in the form of mantle plume along the lithospheric fault to form the deposit.The ultimate power for tellurium mineralization was from H2 flow with high energy,which was produced through radiation from the melted iron of the Earth' s outer core.The H,flow results in the Earth's degassing,as well as the mantle and crust's uplift.