This study focuses on the Lower–Middle Triassic Montney, Sunset Prairie, Doig and Halfway formations from the foreland basin of the Canadian Cordillera (Alberta and British Columbia). Based on core and outcrop descriptions, the correlation of 400 wells, and on mineralogical analyses, this study interprets the basin-scale, 3D-stratigraphic architecture of these formations and discusses the controls on its evolution. Well correlation highlights four sequences (1–4) interpreted to occur in two second-order cycles (A and B). In this work, the Early Triassic Montney Formation and the early Middle Triassic Sunset Prairie Formation are interpreted to consist of three third-order sequences (1–3) related to the first second-order cycle (cycle A). The Middle Triassic Doig and Halfway formations are interpreted to consist of a fourth sequence (4) related to a second second-order cycle (cycle B). Integration of the stratigraphic surfaces with previously published biostratigraphic analyses emphasizes a major time gap of c. 2 myr between these two cycles, interpreted to record a major reorganization of the basin. Mineralogical analyses suggest that during cycle A, sediments were delivered from the east (Canadian Shield); whereas in cycle B, additional sources from the west (proto-Canadian Cordillera) occurred. This study shows that the stratigraphic architecture evolution was affected by the structural heritage of the basin and continental geodynamic evolution. This study provides a large-scale understanding on the controls of the stratigraphic architecture of the Lower and Middle Triassic strata, suggesting local and regional controls on the reservoir extension and unconventional play configuration within these strata.

中文翻译：

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加拿大西部下三叠统地层的 3D 地层结构、沉积收支和来源：主要盆地结构重组的证据

本研究的重点是加拿大山脉前陆盆地（阿尔伯塔和不列颠哥伦比亚省）的下中三叠统 Montney、Sunset Prairie、Doig 和 Halfway 地层。本研究基于岩心和露头描述、400 口井的相关性以及矿物学分析，解释了这些地层的盆地尺度、3D 地层结构，并讨论了对其演化的控制。井相关突出显示四个序列 (1-4)，解释为发生在两个二阶循环（A 和 B）中。在这项工作中，早三叠世蒙尼组和早中三叠世日落草原组被解释为由三个与第一次二阶旋回（旋回A）相关的三阶层序（1-3）组成。中三叠世 Doig 和 Halfway 地层被解释为由与第二次二阶旋回（旋回 B）相关的第四层序 (4) 组成。地层表面与先前发表的生物地层分析的整合强调了 c 的主要时间间隔。这两个周期之间的 2 米，解释为记录盆地的重大重组。矿物学分析表明，在循环 A 期间，沉积物从东部（加拿大地盾）输送；而在周期 B 中，发生了来自西部（原始加拿大山脉）的其他来源。本研究表明，地层构造演化受盆地构造遗产和大陆地球动力学演化的影响。