摘要
对泥炭、褐煤样品进行了高压（0.1～2GPa）、高温（200～800℃）模拟实验，并用微量气体同位素测定系统（GC－C－MS）测定了气态产物的碳同位素值。在400℃的温度条件下，乙烷、丙烷、正丁烷碳同位素值有随压力升高而变重的趋势，并出现了碳同位素局部反序的特征（δ13C2＞δ13C3）；在600℃、1GPa和1．5GPa的温压条件下，甲烷和乙烷的δ13C（PDB）值偏重，分别约为-15．0‰和16．0‰，也重现了δ13C值局部反序的现象（δ13C1＞δ13C2）;在800℃、2GPa的温压条件下，甲烷产物仍然稳定存在。结果说明，压力也是影响样品气态产物演化的重要因素。
Immature organic matter (peat and lignite) were pyrolysized at temperatures ranging from 200 to 400℃ under high pressure ranging from 0.1 to 2 GPa in a closed system, and δ13℃ values of gaseous hydrocarbon generated from organic matter were measured by GC-C-MS system. At 400℃, for the peat samples, the δ13C values of ethane, propane and butane trend to become heavy with pressure increasing. Furthermore, the distribution of δ13C value for each sample has a partially reverse order characteristics, that is, δ13C2 > δ13C3. For lignite samples, there is the same characteristics at 400℃ under pressure of 1. 5 GPa: δC2 > δ13C3 > δ13C4. At 600℃,δ13C (PDB) values of methane in peat and lignite samples are heavy, and are - 15. 4‰ and - 16. 3‰,respectively; δ13C values of ethane are -20. 0‰ and - 21. 4‰, respectively, and the distribution of δ13C value also has a partially reverse order characteristics of δ13C1 > δ13C2. At 800℃ and under 2 GPa, methane has been detected in peat sample, it can be induced that high pressure makes methane more thermodynamically stable at high temperature, and δ13C value of methane in this sample is - 26. 9‰. The results indicate that pressure is one of the important factors that influence the distribution of δ13C values, it maybe causes carbon isotope fractionation, whichresults to reverse distribution of δ13C values during the evolution of organic matter.
出处
《地球化学》
CAS
CSCD
北大核心
2000年第1期73-76,共4页
Geochimica
基金
中国科学院院长基金
关键词
高温
高压
碳同位素
气态产物
模拟实验
high-temperature
high-pressure
carbon isotope
patially reverse order
