THE INTERRELATIONSHIP OF BIOLOGICAL MARKER MATURITY PARAMETERS AND MOLECULAR YIELDS DURING CONTACT-METAMORPHISM
THE INTERRELATIONSHIP OF BIOLOGICAL MARKER MATURITY PARAMETERS AND MOLECULAR YIELDS DURING CONTACT-METAMORPHISM
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DOI：
10.1016/0016-7037(93)90147-o
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发表时间：
1993-08-01
影响因子：
5
通讯作者：
ABBOTT, GD
中科院分区：
文献类型：
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作者：
BISHOP, AN;ABBOTT, GD
侏罗纪粉砂岩样品的采集以厘米为单位，随着距辉绿岩岩脉（苏格兰西北部斯凯岛）距离的增加而变化。有机岩石学观察和有机地球化学分析表明了该单一岩性层位中有机质的恒定来源和类型。因此，生物标记分布随距堤坝接触面距离的变化可以与入侵的热影响明确相关。随着接近堤坝接触面，这些样品的镜质体反射率（R0 平均值）值逐渐从 0.35% 增加到 3.60%。通过样品提取物的 GCMS 分析测量了四个经典生物标记成熟度参数（20S/(20S + 20R)、TA/(TA + MA)、C20/(C20 + C28) 和 22S/(22S + 22R)）。将这些分子参数的变化与单个生物标记化合物浓度的变化进行比较，以相对于提取的岩石质量表示。该比较表明，这些分子参数不受仅在游离饱和或芳香烃结构中操作的常规产物-反应物关系（手性异构化、芳构化或侧链裂化反应）的控制。从大分子和/或官能化部分（碳氢化合物或非碳氢化合物）释放/形成，然后是化合物损失，在该特定热状态的所有四种情况下提供了替代范例。然而，不能完全排除游离甾烷或高藿烷中的直接手性异构化作为过程混合物的贡献者。类似地，游离烃馏分中的芳构化可能占三芳族类固醇的一部分。
Jurassic siltstone samples were collected, on a centimetre scale, as a function of increasing distance from a dolerite dyke (Isle of Skye, northwest Scotland). The constant origin and type of the organic matter in this single lithological horizon is indicated by organic petrological observations as well as organic geochemical analyses. Therefore, changes in biological marker distributions, with distance from the dyke contact, can be unequivocally correlated with the thermal influence of the intrusion. The vitrinite reflectance (R0 Average) values of these samples increase gradually from 0.35% to 3.60% as the dyke contact is approached. Four classical biological marker maturity parameters (20S/(20S + 20R), TA/(TA + MA), C20/(C20 + C28), and 22S/(22S + 22R)), have been measured from GCMS analyses of the sample extracts. Changes in these molecular parameters were compared with changes in the concentrations of the individual biological marker compounds, expressed relative to mass of rock extracted. This comparison revealed that these molecular parameters are not governed by the conventional product-reactant relationships (chiral isomerisation, aromatisation or side-chain cracking reactions) operating solely in the free saturated or aromatic hydrocarbon structures. Release/formation from macromolecular and/or functionalised moieties (hydrocarbon or non-hydrocarbon) followed by compound loss provide an alternative paradigm in all four cases in this particular thermal regime. Direct chiral isomerisation in the free sterane or homohopane cannot, however, be completely ruled out as a contributor to an admixture of processes. Similarly, aromatisation in the free hydrocarbon fraction may account for a proportion of the triaromatic steroids.