Submarine slope channel systems have complicated three‐dimensional geometries and facies distributions, which are challenging to resolve using subsurface data. Outcrop analogues can provide sub‐seismic‐scale detail, although most exhumed systems only afford two‐dimensional constraints on the depositional architecture. A rare example of an accessible fine‐grained slope channel complex set situated in a tectonically quiescent basin that offers seismic‐scale, down‐dip and across‐strike exposures is the Klein Hangklip area, Tanqua‐Karoo Basin, South Africa. This study investigates the three‐dimensional architecture of this channel complex set to characterise the stratigraphic evolution of a submarine channel‐fill and the implications this has for both sediment transport to the deep‐oceans and reservoir quality distribution. Correlated sedimentary logs and mapping of key surfaces across a 3 km2 area reveal that: (i) the oldest channel elements in channel complexes infill relatively deep channel cuts and have low aspect‐ratios. Later channel elements are bound by comparatively flat erosion surfaces and have high aspect‐ratios; (ii) facies changes across depositional strike are consistent and predictable; conversely, facies change in successive down depositional dip positions indicating longitudinal variability in depositional processes; (iii) stratigraphic architecture is consistent and predictable at seismic‐scale both down‐dip and across‐strike in three‐dimensions; (iv) channel‐base‐deposits exhibit spatial heterogeneity on one to hundreds of metres length‐scales, which can inhibit accurate recognition and interpretations drawn from one‐dimensional or limited two‐dimensional datasets; and (v) channel‐base‐deposit character is linked to sediment bypass magnitude and longevity, which suggests that time‐partitioning is biased towards conduit excavation and maintenance rather than the fill‐phase. The data provide insights into the stratigraphic evolution and architecture of slope channel‐fills on fine‐grained continental margins and can be utilised to improve predictions derived from lower resolution and one‐dimensional well data.

中文翻译：

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挖掘出的海底斜坡通道系统的地层等级和三维演化

海底斜坡通道系统具有复杂的三维几何形状和相分布，使用地下数据很难解决这些问题。露头类似物可以提供亚地震尺度的细节，尽管大多数挖掘系统仅对沉积结构提供二维约束。南非 Tanqua-Karoo 盆地的 Klein Hangklip 地区是一个罕见的例子，它位于构造静止的盆地中，提供地震尺度、下倾和横向暴露，是一个可接近的细粒斜坡通道复合体。本研究调查了该通道复合体的三维结构，以表征海底通道填充物的地层演化及其对沉积物向深海的输送和储层质量分布的影响。相关沉积测井和 3 平方公里区域内关键表面的测绘表明：(i) 河道复合体中最古老的河道元素填充了相对较深的河道切口，纵横比较低。较晚的通道元素被相对平坦的侵蚀面所束缚，并且具有高纵横比；(ii) 整个沉积走向的相变是一致且可预测的；相反，连续向下沉积倾角位置的相变化表明沉积过程的纵向变化；(iii) 地层结构在地震尺度上在三个维度上的下倾和跨走向都是一致和可预测的；(iv) 通道基础沉积物在 1 到数百米的长度尺度上表现出空间异质性，可以抑制从一维或有限二维数据集得出的准确识别和解释；(v) 河道-基底-沉积特征与沉积物旁路大小和寿命有关，这表明时间分区偏向于管道开挖和维护，而不是填充阶段。这些数据提供了对细粒大陆边缘斜坡通道填充物的地层演化和结构的深入了解，并可用于改进从较低分辨率和一维井数据中得出的预测。