Department of Geology and Geochemistry, Stockholm University, Stockholm, Sweden.
Geobiology. 2010 Jan;8(1):37-44. doi: 10.1111/j.1472-4669.2009.00223.x. Epub 2009 Nov 11.
Steranes and hopanes are organic biomarkers used as indicators for the first appearance of eukaryotes and cyanobacteria on Earth. Oil-bearing fluid inclusions may provide a contamination-free source of Precambrian biomarkers, as the oil has been secluded from the environment since the formation of the inclusion. However, analysis of biomarkers in single oil-bearing fluid inclusions, which is often necessary due to the presence of different generations of inclusions, has not been possible due to the small size of most inclusions. Here, we have used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to monitor in real time the opening of individual inclusions trapped in hydrothermal veins of fluorite and calcite and containing oil from Ordovician source rocks. Opening of the inclusions was performed by using a focused C(60)(+) ion beam and the in situ content was precisely analysed for C(27)-C(29) steranes and C(29)-C(32) hopanes using Bi(3)(+) as primary ions. The capacity to unambiguously detect these biomarkers in the picoliter amount of crude oil from a single, normal-sized (15-30 mum in diameter) inclusion makes the approach promising in the search of organic biomarkers for life's early evolution on Earth.
甾烷类化合物和藿烷类化合物是用于指示地球上真核生物和蓝藻首次出现的有机生物标志物。含油流体包裹体可以提供无污染的前寒武纪生物标志物来源，因为自包裹体形成以来，油就与环境隔离了。然而，由于存在不同世代的包裹体，通常需要对单个含油流体包裹体中的生物标志物进行分析，但由于大多数包裹体的体积较小，因此一直无法进行分析。在这里，我们使用飞行时间二次离子质谱（ToF-SIMS）实时监测氟石和方解石热液脉中捕获的、含有奥陶纪源岩油的单个包裹体的开启过程。通过使用聚焦的 C(60)(+)离子束来开启包裹体，并用 Bi(3)(+)作为初级离子，对 C(27)-C(29)甾烷类化合物和 C(29)-C(32)藿烷类化合物的原位含量进行精确分析。该方法能够在单个、正常大小（直径为 15-30 微米）包裹体中从皮升级别数量的原油中明确检测到这些生物标志物，这使得该方法有望在寻找地球上早期生命演化的有机生物标志物方面取得突破。
