Distinguishing trunk channels and delta-plain distributary channels in ancient systems can be difficult due to poor or incomplete data (e.g., limited outcrop or sparse well data). Accurate channel classification is required to reconstruct the plan view of channel networks in a paralic fluvio-deltaic system and to quantify source-to-sink systems. Channel formative mechanisms, such as allogenic versus autogenic and avulsion versus bifurcation, also remain equivocal. In this paper we classify channel types and quantify their discharge and dimensions in an ancient paralic depositional system of the Late Cretaceous Gallup system, New Mexico, in a recently developed high-resolution sequence stratigraphic framework. Six key facies associations are identified and integrated into a detailed facies architectural analysis using bedding diagrams from two outcrop cliffs. Backwater lengths are calculated and used for interpretation of channel forming mechanisms and classification of channel types. Two types of channels are interpreted in the study area: meandering fluvial avulsive distributary channels formed in the upstream backwater region in an upper delta plain with a paleodischarge of 280–410 m3/s, and terminal distributary channels in a subaqueous lower delta plain with a paleodischarge of 80–190 m3/s. The results show that upper-delta-plain fluvial distributary channels are formed by erosive avulsion and resemble fluvial meandering rivers characterized by laterally accreting point bars and a wide range of paleocurrents, whereas terminal distributary channels are formed by both avulsion and bifurcation and show more aggradation with lateral confinement and relatively larger width-to-depth ratios of individual channel stories. The quantification of channels and their depositional system provides new data from a well-known ancient system for the global database and comparison with other modern and ancient systems.

中文翻译：

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使用露头对古代系统中的平行通道亚环境进行分类：白垩纪盖洛普系统，美国新墨西哥州

由于数据差或数据不完整（例如露头数据有限或井眼数据稀疏），在古代系统中很难区分干渠和三角洲平原的分布渠。需要精确的通道分类，才能在顺流-三角洲系统中重建通道网络的平面图并量化源到汇系统。通道形成机制，例如同种异体与自体异体以及撕脱与分叉，也仍然是模棱两可的。在本文中，我们在新近开发的高分辨率层序地层学框架中，对新墨西哥州晚白垩世盖洛普系统的古代抛物线沉积系统中的通道类型进行了分类，并对它们的流量和尺寸进行了量化。使用两个露头悬崖的地层图，确定了六个关键相的关联并将其整合到详细的相结构分析中。计算回水长度，并将其用于解释河道形成机理和对河道类型进行分类。研究区域解释了两种类型的河道：在上游三角洲平原上游回水区形成的河床冲积性河床分布分布，古土壤流量为280-410 m3 / s，在三角洲下水下平原区的末级分布河道分布为河床。古溢水量为80-190立方米/秒。结果表明，上三角平原河流分流河道是由侵蚀性侵蚀形成的，类似于河流蜿蜒的河流，其特征是侧向点积点和广泛的古流，终端分布的河道由撕脱和分叉形成，并随着侧向约束和单个河道层的相对较大的宽深比而显示出更多的凝结。通道及其沉积系统的量化为全球数据库提供了来自一个著名的古代系统的新数据，并与其他现代和古代系统进行了比较。