The role of organic carbon in the Southern Uplands-Down-Longford Terrane accretionary prism, Scotland and Ireland
The role of organic carbon in the Southern Uplands-Down-Longford Terrane accretionary prism, Scotland and Ireland
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DOI：
10.1144/petgeo2022-059
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发表时间：
2023-06
影响因子：
1.7
通讯作者：
J. Parnell;J. Armstrong;N. Blamey;A. Boyce;A. Schito;D. Muirhead
中科院分区：
文献类型：
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作者：
J. Parnell;J. Armstrong;N. Blamey;A. Boyce;A. Schito;D. Muirhead
南部高地-下朗福德地体增生棱柱体中的碳质页岩在下古生界具有极高的生烃潜力。棱柱体中的构造增厚促进了石油的快速生成。页岩层被由低渗透性杂砂岩组成的厚浊积岩分隔开，因此，在高流体压力下，油要么沿沿着页岩层面聚集，要么迁移到裂缝性杂砂岩中。汇集的石油凝固成沥青，在当地形成了吨级的矿床，作为煤炭开采。富含碳的页岩还从海水中隔离了大量的硫，这些硫首先在早期成岩作用期间沉淀为黄铁矿，然后在流体流过页岩床期间进一步沉淀。石油也是含硫的。在增生棱柱体的演化过程中，变形集中在页岩层上，这与沉淀沥青和硫化物的流体流动密切相关。古流体中也富含甲烷和氢，类似于现代增生棱柱体中的流体。补充材料：在下古生界、南部高地-下朗福德地体（位置如图6所示）中寻找煤炭的详细地点可在www.example.com上获得https://doi.org/10.6084/m9.figshare.c.6691597
Carbonaceous shales in the Southern Uplands-Down-Longford Terrane accretionary prism had extremely high potential for hydrocarbon generation in the Lower Paleozoic. Structural thickening in the prism enhanced the rapid generation of oil. Shale horizons are separated by thick turbidites composed of low-permeability greywackes, so oil under high fluid pressure either pooled along shale bedding surfaces or migrated into fractured greywackes. Pooled oil became solidified to bitumen, which locally formed deposits on a scale of tonnes, mined as coal. The carbon-rich shale also sequestered large amounts of sulfur from seawater, which precipitated as pyrite firstly during early diagenesis, then further during fluid flow through the shale beds. The oil was also sulfur-bearing. Deformation focused on the shale beds during the evolution of the accretionary prism would have been closely related to the fluid flow which precipitated bitumen and sulfides. The palaeo-fluids were also anomalously rich in methane and hydrogen, similar to fluids venting from modern accretionary prisms. Supplementary material: details of localities searched for coal in Lower Palaeozoic, Southern Uplands-Down-Longford Terrane (locations shown in Fig. 6 ) are available at https://doi.org/10.6084/m9.figshare.c.6691597