长直链烷基苯及其异构体母质来源研究及地球化学意义

烷基苯系列化合物广泛分布在岩石圈中，但其母质来源和指示意义仍存在一定争议。对四川盆地晚三叠世须家河组和鄂尔多斯盆地晚三叠世延长组烃源岩样品进行了岩石热解及GC-MS（GC-MS-MS）分析，检测出一系列的长直链烷基苯及其异构体。烃源岩基本地球化学参数表明四川盆地和鄂尔多斯盆地样品均遭受过较强程度的微生物降解作用，有机质类型以腐殖腐泥型为主，埋藏期间经历过一定程度的黏土矿物催化作用，以弱氧化的淡水沉积为主。此外，两个研究区样品中长直链烷基苯及其异构体的相对含量呈现出相反的分布模式，在前人研究基础上并结合研究区烃源岩沉积环境和热演化背景，认为烷基苯系列化合物可能来自于类脂化合物（如脂肪酸和脂肪醇）或简单芳烃化合物与类脂化合物的反应，且热作用会导致长直链烷基苯向其异构体转化。综合以上研究表明长直链烷基苯及其异构体可以作为一种指示有机质热演化程度和母质来源的有效参数。

Distribution Characteristics of Long-chain Alkylbenzene and Its Isomers

Alkylbenzene series compounds widely distributed in the lithosphere, but its parent material source and the indicating significance is still in controversy.This paper focused on the samples of saturated hydrocarbon fractions which were from the Late Triassic Xujiahe Formation in central Sichuan Basin and the Late Triassic Yanchang Formation in Ordos Basin.A series of long-chain alkylbenzene and its isomers (branched alkylbenzene) were tested by GC-MS analysis.The results indicated those samples had I-Ⅱ1 type organic matters and formed in a sub-oxidizing environment with strong clay catalysis and bacterial degradation, the sedimentary environment of samples are the similar.However, that the relative content of long-chain alkylbenzene and its isomers distribution patterns are different, on the basis of predecessors′ research combined with hydrocarbon source rocks in the study area and thermal evolution background, suggested that lipid such as fatty and alcohol, or simple aromatic compounds with lipid reaction is a possible source of alkylbenzene, in addition, the thermal effect leads to long-chain alkylbenzene transform to its isomers.The study shows that long-chain alkylbenzene and its isomers indicate the effective degree of thermal evolution of organic matter and the source of parent material parameters.