火山活动与深部碳循环的关系  

VOLCANIC ACTIVITIES AND DEEP CARBON CYCLE

作　　者：郭正府[1] 李晓惠[1] 张茂亮[1] 

机构地区：[1]中国科学院地质与地球物理研究所新生代地质与环境重点实验室,北京100029

出　　处：《第四纪研究》2010年第3期497-505,共9页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:40773023)资助

摘　　要：火山活动是导致地球深部碳向地表输送的重要途径之一,它促进了地球层圈物质交换与深部循环作用.目前,火山活动与深部碳循环关系的研究主要集中在： 1）火山喷发向大气圈中输送CO2气体的通量与总量; 2）火山气体的来源及其演变历史; 3）不同类型的火山喷发（例如,大火山岩省、洋中脊和俯冲带火山活动）对地球深部碳循环贡献的差异.文章通过对青藏高原北部阿什库勒火山群1951年阿什火山喷发物斑晶中原生岩浆包裹体和基质玻璃的实验室测定表明,阿什火山喷出的气体成分主要由H2O,CO2,S,Cl和F组成,利用＂岩石学方法＂计算的阿什火山喷发向大气圈输送的CO2气体总量为1.01×10^9kg.Research content for a relationship between volcanic activities and deep carbon cycle mainly contains （1） estimations of total mass and flux of volcanic degassing volatiles into the atmosphere, （2）determinations of source field of volcanic volatiles, （3）evolutions of volatiles released from volcanic eruptions from asthenospheric mantle to atmosphere, and （4）contributions of three main types of large volcanic activities（ including Large Igneous Provinces,mid-ocean ridge basahs and subduction-derived volcanism）to deep carbon cycle. Main research method based on analysis in composition of melt inclusion trapped in phenocryst minerals in volcanic eruptive products is as follows ： （ 1 ） Sample collections of volcanic rocks in field work are responsible for determinations of volcanic volatile compositions. （2） Compositions and concentrations of volatiles （ including Cl, S, F） in melt inclusions entrapped in phenocryst mineral crystals of volcanic rocks are analyzed using the wavelength dispersive electron microprobe. Analytical conditions are 10 - 20kV accelerating voltage and beam current of 5 - 15nA for melt inclusions and matrix glass. 1 - 10 and 5 - 15μm-diameter-wide electron beams are used for melt inclusions and matrix glass analysis, respectively. Sulfur concentration is measured at the mean peak position determined for each melt inclusion using a 60s count time. However, elements F and Cl are determined for 20s and 30s, respectively. Relative analytical precision is 10% for S, 10% for F and 5% for Cl based on repeated analyses of the reference glasses. Detection limit is 180ppm for S,300 ppm for Cl and 200ppm for F on the basis of a peak-to-background ratio. We have devised to doubly polish each melt inclusion （ideally producing a rectangular window）for analysis of H2O and CO2 contents by FTIR spectroscopy. （3）Total weight of volcanic volatiles emitted into the atmosphere are calculated using the ＂ petrologic method＂ based on analysis of compositions and concentra

关 键 词：火山活动 碳循环 岩浆包裹体 火山气体 阿什火山 

分 类 号：P317[天文地球—固体地球物理学]