4β-甲基甾烷的确认及其地质意义

INDENTIFICATION OF 4β-METHYL STERANES AND ITS GEOLOGICAL SIGNIFICANCE

经用TSQ－70 GC／MS／MS仪器分析，从北部湾盆地不同埋深的生油岩样品中，检测出4－甲基甾烷系列。根据质谱特征、标样共注、文献对照，确认其结构为4α－甲基甾烷和4β－甲基甾烷系列。对该区4β－甲基甾烷的分布及热演化规律进行了讨论，提出4α-Me ααα（20R）/（4α-Me ααα+4β-Meααα)(20R）甾烷是一个成熟度参数。

By TSQ-70 GC/MS/MS mass spectrometer from the source rock samples tak- en at different burial depth in Beibu Gulf basin.They were indentified as 4α-methyl sterane and 4β-methyl sterane series from mass spectrum characteristic,injection standard with sample and comparison with other literatures.The distribution and thermal evolution of 4β-methyl steranes in the area are discussed,and 4α-Me ααα/ (4α-Me ααα+4β-Me ααα)(20R) is proposed as a maturity parameter.