Reconstructing the paleo-environmental conditions that prevailed during the deposition of sediments provides invaluable information for paleo-ecological and evolutionary reconstructions and petroleum exploration. However, reconstructions of depositional environments based on sedimentary structures are often ambiguous, in particular if only core or mud chip samples are available. Organic proxies provide another avenue for paleo-depositional reconstruction of sedimentary rocks and related crude oils, but there is only a limited number of proxies and these rarely allow for unambiguous interpretations. Although tricyclic terpanes are among the most widely used depositional proxies, few studies calibrated terpane proxies with a large variety of samples. Here we show based on analyses of 485 oil and sediment samples from a variety of formations with well characterized depositional environments spanning in age from the late Paleozoic to Neogene, that the distribution of C + C, C and C tricyclic terpanes in ternary diagram has high predictive power to differentiate between marine/saline lacustrine, freshwater lacustrine, swamp and fluvial/deltaic depositional environments. Our analyses indicate that the tricyclic terpanes related parameters are not adulterated by even severe biodegradation or thermal maturation processes throughout the whole oil window, and our analyses of the largest terpane compilation to date encompassing >700 samples indicate robust proxy potential in post-Ordovician settings around the globe. This facile and widely applicable method for ecosystem definition can enhance a variety of petroleum, sedimentary and paleo-ecological studies and should best be used in concert with other organic and inorganic proxies for a detailed reconstruction of paleo-ecological conditions.

中文翻译：

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短链三环萜烷作为古沉积条件的有机替代物

重建沉积物沉积期间普遍存在的古环境条件为古生态和进化重建以及石油勘探提供了宝贵的信息。然而，基于沉积结构的沉积环境重建通常是不明确的，特别是在只有岩心或泥片样本可用的情况下。有机代理为沉积岩和相关原油的古沉积重建提供了另一种途径，但代理的数量有限，而且很少允许明确的解释。尽管三环萜烷是最广泛使用的沉积替代物之一，但很少有研究用多种样品校准萜烷替代物。在这里，我们通过对来自晚古生代到新近纪的沉积环境特征良好的各种地层的 485 个石油和沉积物样品的分析表明，三元图中 C + C、C 和 C 三环萜烷的分布具有较高的分布性。区分海洋/咸水湖、淡水湖、沼泽和河流/三角洲沉积环境的预测能力。我们的分析表明，在整个石油窗口中，即使是严重的生物降解或热成熟过程，三环萜烷相关参数也不会掺假，并且我们对迄今为止最大的萜烷汇编（包含> 700个样本）的分析表明，在后奥陶世环境中具有强大的代理潜力。全球。这种简便且广泛适用的生态系统定义方法可以增强各种石油、沉积和古生态研究，并且最好与其他有机和无机代理一起使用，以详细重建古生态条件。