Quantification of internal heterogeneity across a submarine channel bend: a unique example from the late Tortonian Tachrift Channel Complex 5 (Taza–Guercif Basin, NE Morocco)

The heterogeneity of a deep marine slope channel complex is investigated through the acquisition of fifty sedimentary logs across three high-quality exposures of the late Tortonian Tachrift Complex 5, which constitutes part of the Neogene sedimentary infill of the Taza–Guercif Basin, NE Morocco. Various metrics extracted from log data (net-to-gross, amalgamation ratio, facies proportions, etc.) are processed to assess heterogeneity trends across the studied deposits. Sedimentological and stratigraphic analyses indicate that the exposures constitute upstream and downstream parts of a large-scale, left-turning channel bend. Sedimentary facies comprise different types of amalgamated sandstones, heterolithic and mud-rich sediments, grouped in channel-fill and overbank facies associations. Architectural elements recognized in channel-fill deposits are mainly lateral-accretion packages (LAPs), with additional elements recognized and recorded for the first time, representing different depositional settings across the channel bend, such as outer-bank bars and inner- to outer-bank transition bars. Analysis of heterogeneity metrics indicates the occurrence of two main types of LAP, which vary depending on their upstream or downstream position across the bend, each with different internal heterogeneity (e.g., mean and lateral trends of net-to-gross, facies proportions, etc.) when compared with other elements deposited across the channel. The range and spatial arrangement of heterogeneity metrics observed could serve as an analog for assessing heterogeneity across channel bends of similar slope channel fills in the subsurface.