The Doig Phosphate Zone (DPZ) is a phosphate-bearing marine unit located at the base of the Doig Formation, in the Triassic section of the Western Canada Sedimentary Basin. The DPZ has a maximum thickness of 90 m and extends across northeastern British Columbia and west-central Alberta. In this study, we characterize the significance and interpret the origin of apatite in the DPZ through mineralogical and geochemical analyses, thin section study, and field emission scanning electron microscopy. The occurrence of apatite in the DPZ is not evenly distributed but restricted to discrete 10 to 20 cm thick beds, located near the base of the DPZ. Phosphorites are of two types: grainstones composed primarily of unconformity-bounded coated grains, and intraclastic phosphorites composed of detrital silt-sized grains and apatite coated grains in a cryptocrystalline phosphatic matrix. The phosphorite beds are records of stratigraphic condensation due to low detrital input during transgression. The erosionally truncated phosphatic coated grains and intraclasts are interpreted to be a result of various phases of phosphatization, exhumation, erosion, reworking, winnowing, and redeposition in alternating quiescence and storms or bottom currents. The abundance of pyrite and chalcophile trace elements, as well as the low concentration of proxy elements for organic matter productivity and preservation, are further evidence of stratigraphic condensation, with sulfidic pore water development and extensive organic recycling promoted by biological activity during the long exposure times. The phosphorites were formed under oxygenated water conditions, as suggested by the depletion in Ce and the presence of a diverse benthic fauna.

中文翻译：

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加拿大西部沉积盆地三叠纪道格磷酸盐带中磷灰石的意义和分布

Doig磷酸盐带（DPZ）是位于加拿大西部沉积盆地三叠纪剖面Doig地层底部的含磷酸盐海洋单元。DPZ的最大厚度为90 m，横跨不列颠哥伦比亚省东北部和艾伯塔省中西部。在这项研究中，我们通过矿物学和地球化学分析，薄片研究以及场发射扫描电子显微镜表征了DPZ中磷灰石的重要性并解释了其起源。DPZ中磷灰石的发生不是均匀分布，而是限于位于DPZ底部附近的离散10至20 cm厚的床层。磷矿有两种类型：主要由不整合边界的涂层晶粒组成的晶粒；碎屑粉状颗粒和磷灰石包覆的颗粒组成的隐晶磷质基质中的碎屑内磷矿。磷矿床是海侵过程中由于碎屑输入少而引起的地层凝结的记录。侵蚀性截断的磷酸涂层颗粒和破骨细胞被认为是在静止，暴风雨或底流交替发生的各个阶段的磷化，发掘，侵蚀，返工，风选和再沉积的结果。黄铁矿和硫属元素微量元素的丰富，以及用于有机物生产率和保存的替代元素的低浓度，进一步证明了地层冷凝，在长期暴露时间中，由于生物活性而促进了硫化孔隙水的发展和广泛的有机循环利用。