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

黑色富碳页岩富集Ni、Mo、Zn、Pb、Cu、Co、U、V、As、Ag、Au、PGE等金属元素。它们也是烃类液体和气体的源层。在某些情况下，特别是在华南早寒武纪的黑色页岩中，这些金属在当地的浓度高到足以进行经济开采。例如，在遵义地区，有薄的富硫化物层，其中含有约4 wt.%的Ni， 2 wt.%的Zn， 0.7 ppm的Au， 50 ppm的Ag， 0.3 ppm的Pt和0.4 ppm的Pd。附近还有其他含V2O5含量超过4 wt.%的黑色页岩矿床。在加拿大育空地区的Nick远景区，泥盆纪中晚期的黑色页岩也被认为含有同样高浓度的Ni、Zn、Au和PGE。阿尔伯塔省东北部也有大量的黑色页岩，尽管金属品位相对较低，但最近已被考虑用于经济开采。这些页岩是Buckton Creek地区白垩系Colorado群的一部分，储量约45亿吨，含Ni、Mo、U、V、Zn、Cu、Co、Li、REE、Y、Th和Sc，金属浓度在ppm至ppm以下。我们希望在这项研究中解决的一个重要问题是，黑色页岩是如何富集金属的，特别是富集到可以进行经济开采的水平。特别是，由于这些页岩已经通过了石油窗口，我们将研究液态碳氢化合物的作用及其与热液流体/盐水的相互作用，在动员和潜在地富集上面提到的一些（可能是很大一部分）金属的页岩中，其浓度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矿床的相对氧化盆地，以及sedex型铅锌矿床。相反，我们将重点研究在缺氧/富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.