The middle (Miaolingian) to upper (Furongian) Cambrian Alum Shale Formation in the DBH15/73 core from south-central Sweden was exposed to local heat from a diabase intrusion, providing an opportunity to investigate the molecular geochemical response to thermal stress. Organic petrological observations and biomarker analyses were conducted to study changes in maturity-indicating parameters and the distribution of high molecular weight polycyclic aromatic hydrocarbons (PAHs) during the maturation process. The DBH15/73 samples exhibit a maturity gradient, ranging from immature at the base to mature in the upper part of the Alum Shale Formation. Multiple maturity-based biomarker parameters were analyzed, and Ts/(Ts + Tm), M30/(M30 + H30), and Hopane H32: 22S/(22S + 22R) of saturated hydrocarbon parameters are found to be more reliable. Ratios of alkylnaphthalenes, alkylphenanthrenes, and alkyldibenzothiophenes (MNR, DNR, TMNr, TeMNr, MPI-1, MPR, MDR, and DMDR) also showed consistent correlations with thermal maturity. Thermal maturation impacted the macromolecular structure, resulting in the aromatization and demethylation, leading to MPy/Py, MChy/Chy, and the sum of unsubstituted 5-ring/4-ring PAH ratios changes with maturity. The influence of thermal maturation outweighs that of uranium radiation in this study, and maturity varies mainly with depth.

中文翻译：

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热入侵对瑞典中南部明矾页岩生物标志物分布的影响


瑞典中南部 DBH15/73 岩心中（苗岭系）至上（芙蓉系）寒武系明矾页岩组暴露于辉绿岩侵入体的局部热量下，为研究分子地球化学对热应力的响应提供了机会。进行有机岩石学观察和生物标志物分析，研究成熟过程中成熟度指示参数的变化和高分子量多环芳烃 （PAHs） 的分布。DBH15/73 样品表现出成熟度梯度，从基部的未成熟到明矾页岩组上部的成熟。分析了多个基于成熟度的生物标志物参数，发现饱和烃参数的 Ts/（Ts + Tm）、M30/（M30 + H30） 和 Hopane H32：22S/（22S + 22R） 参数更可靠。烷基萘、烷基菲和烷基二苯并噻吩（MNR、DNR、TMNr、TeMNr、MPI-1、MPR、MDR 和 DMDR）的比例也显示出与热成熟度的一致相关性。热成熟影响大分子结构，导致芳构化和去甲基化，导致 MPy/Py、MChy/Chy 和未取代的 5 环/4 环 PAH 比率之和随成熟度而变化。在这项研究中，热成熟的影响超过了铀辐射的影响，成熟度主要随深度而变化。