The distribution, nature and control of metal concentrations in black shales, and relationships with hydrocarbon source rocks

黑色富碳页岩因其异常的金属富集而引人注目，包括Ni、Mo、Zn、Pb、Cu、Co、U、V、As、Ag、Au和PGE。 它们也是烃类液体和气体的源层。 在某些情况下，特别是在中国南方寒武纪早期的黑色页岩中，这些金属的浓度在当地足够高，可以进行经济开发。 例如，在遵义地区，存在薄的富硫化物层，其含有约4 wt.% Ni，2重量% Zn、0.7 ppm Au、50 ppm Ag、0.3 ppm Pt和0.4 ppm Pd。 附近还有其他黑色页岩矿床，五氧化二钒 在加拿大，已知育空地区尼克前景的泥盆纪中期至晚期黑色页岩也含有类似的高浓度镍、锌、Au和铂族元素。 在阿尔伯塔东北部也有大量的黑色页岩，最近被考虑用于经济开发，尽管金属品位相对较低。这些页岩构成了Buckton Creek地区白垩纪科罗拉多群的一部分，构成了约45亿吨的资源，含有Ni、Mo、U、V、Zn、Cu、Co、Li、REE、Y、Th和Sc，金属浓度为ppm至100 ppm水平。 我们希望在这项研究中解决的一个重要问题是，黑色页岩中的金属是如何富集的，特别是如何富集到允许经济开采的水平。 特别是，由于这些页岩已经通过了石油窗口，我们将研究液态烃的作用及其与热液流体/盐水的相互作用，在动员和可能富集页岩中的一些和可能的大比例的上述金属，远高于黑色页岩中通常预期的浓度。 然而，我们将排除产生Cu-Co-U矿床的相对氧化的盆地，以及SEDEX型Pb-Zn矿床。 相反，我们将重点关注在缺氧/缺氧盆地中形成的主要含Ni、Co、Mo、V、Zn、PGE和Au的矿床。 我们将研究的第二个问题是黑色页岩中金属浓度和比例之间的关系，以及它们作为油气聚集载体的效用，以及作为评估氧化还原和有机保存模型的工具。

Black, carbon-rich shales are conspicuous for their unusual metal enrichment, including Ni, Mo, Zn, Pb, Cu, Co, U, V, As, Ag, Au and PGE. They are also the source beds for hydrocarbon liquids and gases. In some cases, notably in the early Cambrian black shales of South China, the concentrations of some of these metals are locally high enough for economic exploitation. For example, in the Zunyi district, there are thin, sulphide-rich layers within that contain about 4 wt.% Ni, 2 wt.% Zn, 0.7 ppm Au, 50 ppm Ag, 0.3 ppm Pt and 0.4 ppm Pd. Nearby, there are other black shale-hosted deposits containing in excess of 4 wt.% V2O5. In Canada, black shales of middle to late Devonian age at the Nick prospect, Yukon are also known to host similarly high concentrations of Ni, Zn, Au and PGE. There are also extensive units of black shale in northeastern Alberta that have been considered recently for economic exploitation, albeit with relatively low metal grades. These shales, which form part of the Cretaceous Colorado Group of the Buckton Creek area, constitute a resource of ~4.5 billion tonnes containing Ni, Mo, U, V, Zn, Cu, Co, Li, REE, Y, Th and Sc with concentrations of metals at the ppm to low 100's of ppm levels. An important question that we wish to address in this research is how black shales are enriched in metals, especially to levels that would allow their economic exploitation. In particular, as such shales have passed through the oil window, we will examine the role of liquid hydrocarbons and their interplay with hydrothermal fluids/brines in mobilising and potentially enriching shales in some and possibly a large proportion of the metals referred to above, to concentrations well above those normally expected in black shales. However, we will exclude the relatively oxidized basins that give rise to Cu-Co-U deposits, as well as the SEDEX-type Pb-Zn deposits. Instead we will focus on deposits containing mainly Ni, Co, Mo, V, Zn, PGE and Au that form in anoxic/euxinic basins. A second question that we will investigate is the relationship between metal concentrations and ratios in black shales and their utility as vectors toward hydrocarbon accumulations, and as tools to evaluate redox and organic preservation models.********