The Hare Indian and Canol Formations, which are part of the Horn River Group in the Northwest Territories, Canada, primarily consist of organic-rich mudstones deposited during the Middle to Late Devonian. The formations were previously considered to represent marine basin fill accumulated in an oxygen-starved distal shelf setting, evidenced by the organic-rich character, pyrite content, and lack of macro-scale bioturbation. The depositional model, paleo‑oxygenation interpretations, and methods of organic carbon preservation presented in this study are in contrast to previous assumptions of the Horn River Group mudstones. Detailed petrographic, sedimentological, and ichnological analyses were carried out on thin sections taken from several cored Horn River Group intervals. These organic-rich mudstone units contain eight distinct microfacies, representing four main sedimentation processes acting on an interpreted distal shelf setting: (1) pelagic suspension settling, (2) plug-like sediment-gravity flows, (3) surge and surge-like low-density turbidity currents, and (4) debrites. Pelagic suspension-settling dominated in distal, quiet waters out of the reach of persistent storm influence. Debrites, plug-like flows, and low-density turbidite processes represent a continuum, wherein storm influence was the dominant driver in sediment delivery. Several morphologically distinct, microscopic biogenic-sedimentary structures (i.e. ichnofossils) have been identified throughout the mudstone intervals, indicative of sediment pore waters that were at least periodically partially oxygenated. Evaluation of total organic carbon content against bioturbation and microfacies interpretation suggest that persistent anoxia was not the dominant factor in organic carbon preservation, but rather a result of a combination of heightened sedimentation and burial rates and possible amplified rates of primary productivity. The results of this study may be applied to evaluations of other organic rich mudstones to enhance paleo-depositional interpretations.

隶属于加拿大西北地区霍恩河群的野兔印度和卡诺尔岩层主要由泥盆纪中晚期沉积的富含有机质泥岩组成。以前，这些地层被认为代表了在缺氧的远古陆架环境中累积的海盆充填物，这由富含有机物的特征，黄铁矿含量和缺乏宏观生物扰动证明。这项研究中提出的沉积模型，古加氧解释和有机碳保存方法与霍恩河群泥岩的先前假设相反。详细的岩石学，沉积学和岩石学分析是对从几个核心霍恩河群间隔取的薄片进行的。这些富含有机质的泥岩单元包含八个不同的微相，代表作用在解释的远洋陆架背景上的四个主要沉积过程：（1）浮游悬浮物沉降，（2）塞状沉积物重力流，（3）浪涌和类似浪涌的低密度浊流，以及（4）碎屑。远洋悬浮水体主要集中在远处的平静水域，不受持续的风暴影响。碎屑，塞状流动和低密度浊积过程代表了一个连续体，其中风暴影响是沉积物输送的主要驱动力。在整个泥岩层段中，已经确定了几种形态学上不同的，微观的生物沉积沉积结构（即鱼类化石），表明沉积物孔隙水至少定期被部分充氧。评估总有机碳含量对生物扰动和微相解释的影响表明，持久性缺氧不是有机碳保存的主要因素，而是沉积和掩埋速率提高以及初级生产力可能提高的速率共同作用的结果。这项研究的结果可用于评估其他富含有机质泥岩，以增强古沉积解释。