深源花岗岩中的碳氢化合物  

Hydrocarbons in the hypogenic granite

作　　者：曾贻善[1] 刘家齐[2] 

机构地区：[1]北京大学地质系,北京100871 [2]中国地质科学院宜昌地质矿产研究所,湖北宜昌443003

出　　处：《地球化学》2001年第5期445-449,共5页Geochimica

基　　金：国家自然科学基金(49673193;40073205);高等学校博士学科点专项科研基金(9700153)

摘　　要：利用石油地球化学的溶剂抽提和气相色谱技术研究了北京延庆碓臼峪花岗岩(深源花岗岩)样品中的可溶有机质,同时用高温处理过的石英砂进行空白对比实验。结果表明,所研究的两个花岗岩样品中均存在少量的高碳数碳氢化合物,且具有相同的成分特征。这为自然界存在深源的长链碳氢化合物提供了新的证据,也为解释花岗岩浆演化晚期水热流体中短链羧酸的成因提供了线索。Soluble organic material in two rock samples from the Duijiuyu granite (hypogenic granite), Yanqing County, Beijing, is studied using conventional solvent extraction and gas chromatography techniques in petroleum geochemistry. The rock samples were taken from the periphery of the granite. The granite wasthoroughly washed with water and dichloromethane, and then crushed and pulverized finer than 0.15 mm using carefully cleaned crusher and mill. After that the rock powder was washed again with dichloromethane. Dichloromethane extraction of granite powder was carried out in an ultrasonic cleaning cell (2 h each run) to dissolute free hydrocarbons possibly existed, and a blank experiment with quartzsand heated at 750 ℃for 20 h was accompanied. The gas chromatographic analysis of extraction fraction obtained suggested the presence of small amounts of hydrocarbons in the granite (see Table).In this study all possible precautions were taken in the field to avoid sampling weathered rock and in the laboratory to prevent contamination during the extraction procedure. It is believed that the hydrocarbons isolated from the Duijiuyu granite are inherent constituents of the rock. The origin of hydrocarbon in granite was briefly discussed on the basis of previous studies. This study provides new evidence of the presence of hypogenic long chain hydrocarbons in the nature, and a helpful clue to understand the origin of short chain carboxylatesin hydrothermal fluids at the late stage of granitic magma evolution.

关 键 词：深源花岗岩 碳氢化合物 溶剂抽提 气相色谱 石英砂 可溶有机质 

分 类 号：P588.121[天文地球—岩石学]