Geochemical Study on Mantle-derived Hydrocarbons.

幔源烃地球化学研究。

基本信息

批准号：
05403002
负责人：
WAKITA Hiroshi
金额：
$ 24.77万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

This study aims at revealing origins, distributions and transportation mechanisms of carbon compounds in the Earth, using samples of natural gases, high temperature volcanic gases and hydrothermal vents from seafloor.We succeeded in carbon isotopic measurement of methane of 10nM with a precision of 5 per mil with a GasChromatograph/Combustion/Mass Spectrometer system combined with a methane concentration line.Most of natural gases from China showed a carbon isotopic distribution among hydrocarbons (C1-C5) wherein delta^<13>C becomes more negative with decreasing molecular weight of hydrocarbons, i.e.delta^<13>C1<delta^<13>C2<delta^<13>C3<delta^<13>C4, which suggests than most of natural gases formed by pyrolysys of organic matters in sediments. High temperature fumaroles collected in Satsuma-iojima contain methane formed by pyrolysys of organic matters in aquifer, which indicates difficulty to detect magma-derived methane without contamination. However, we developed a new methane extraction and concentration line for water samples and detected methane formed by an inorganic reaction in hydrothermal vent fluids collected in East Pacific Rise.This study showed the developed concentration method combined with the GC/C/MS enabled us to investigate carbon compound in mantle. We will continue to imporve our methane concentration method and will apply the technique to other samples such as fluid inclusions in rocks.

这项研究旨在揭示地球中碳化合物的起源，分布和运输机制，使用天然气的样品，高温火山气体和海底的水热通风量。我们在10nm的碳同位素测量中取得了10nm的碳同位素测量，每平方米，每平方米的含量均高于10nm的甲烷，均具有5Nm的含量，该甲烷的含量为5 showed a carbon isotopic distribution among hydrocarbons (C1-C5) wherein delta^<13>C becomes more negative with decreasing molecular weight of hydrocarbons, i.e.delta^<13>C1<delta^<13>C2<delta^<13>C3<delta^<13>C4, which suggests than most of natural gases formed by pyrolysys of organic matters in沉积物。在satsuma-iojima中收集的高温富马氏菌包含含有有机物的含水层中的甲烷，这表明很难检测岩浆衍生的甲烷而不污染。然而，我们开发了一种新的甲烷提取和浓度线，用于水样，并检测到在东太平洋上升中收集的水热通风液中，该甲烷由无机反应形成。这项研究表明，开发的浓度方法与GC/C/MS相结合，使我们能够研究地幔中的碳化合物。我们将继续引起我们的甲烷浓度方法，并将该技术应用于其他样品，例如岩石中的流体夹杂物。