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对四川广元地区寒武纪、二叠纪和石炭纪部分海相碳酸盐岩地层中沥青的Mo同位素和微量元素进行了测定.结果表明,该区不同时期沥青的δ98 Mo有较大的变化范围(+0.34‰～+1.71‰),总体上,接近缺氧沉积岩δ98 Mo的范围.寒武纪海相地层中沥青具有明显的δEu正异常(0.75～1.68),其Mo、Ni、V等氧化还原敏感元素含量相对较高,且具有明显偏重的δ98 Mo(1.17‰～1.71‰),特别是下寒武统筇竹寺组的一个样品(Hs-qzs)出现明显的δEu正异常(1.68),可能与同期强烈的海底热液活动有关.热液喷发过程中产生的大量硫化氢,导致偏重δ98 Mo以及Mo、Ni、V等元素的富集.虽然该区不同时期的海相碳酸盐岩中沥青的TMV与TMNi没有明显的相关性,但是不同时期(寒武纪、二叠纪和石炭纪)沥青的δ98 Mo与V/Ni比值的分布区域存在一定的差异,有可能与来源不同有关,暗示δ98 Mo有可能仍然保存着部分源岩的性质,特别是下寒武统筇竹寺组(Hs-qzs)的TMV与TMNi相对偏高,可能与海底热液作用及后期相对较强的降解作用有关.
The Mo isotopes and trace elements of asphalt in some marine carbonate rocks in the Cambrian, Permian and Carboniferous of Guangyuan area of Sichuan Province were measured.The results showed that the δ98 Mo of asphalt in different parts of the area changed greatly (+ 0.34 ‰ ~ + 1.71 ‰), which is close to the range of δ98 Mo of the anoxic sedimentary rocks.Asphalt in the Cambrian marine strata has obvious δEu positive anomaly (0.75-1.68) and its redox such as Mo, Ni and V The δ8u positive anomalies (1.68 ~ 1.17 ‰ ~ 1.71 ‰), especially for the samples from the Lower Cambrian Qiongzhusi Formation (Hs-qzs) Which may be related to the intense seafloor hydrothermal activities in the same period.The large amount of hydrogen sulfide generated during the hydrothermal eruption led to the enrichment ofδ98 Mo and Mo, Ni, V etc. Although marine carbonate rocks of different periods There is no obvious correlation between TMV and TMNi in asphalt, but there are some discrepancies between δ98 Mo and V / Ni ratio in different ages (Cambrian, Permian and Carboniferous) asphalt, which may be related to different sources , Suggesting that δ98 Mo may still retain some of the source rocks The TMV and TMNi of the Lower Cambrian Hs-qzs are relatively high, which may be related to the hydrothermal effect of the seafloor and the relatively strong degradation later.