Characterizing heterogeneity in a glaciofluvial deposit using architectural elements, Limehouse, Ontario, Canada

Abstract

Major hydrocarbon and groundwater reservoirs are commonly hosted within coarse-grained alluvial deposits that contain a high degree of sedimentary heterogeneity. This paper presents a detailed characterization of the sedimentary heterogeneity of fluvial–deltaic deposits using architectural element analysis (AEA). Sedimentological data collected from outcrop faces exposing Late Quaternary glaciofluvial deposits in southern Ontario, Canada, is recorded in 31 sedimentary logs. These logs are used to identify nine different facies types, including gravel facies (Gm, Gp, Gt), sand facies (Sr, Sp, St, Ss), and fine-grained facies (Fl and Fd). Variations in facies associations and geometries are defined by five architectural elements (AEs): sand complex (SC), gravel sheet (GS), fine-grained sheet (FS), gravel foreset body (GFB), and concave fill (CF) elements. The spatial arrangement of bounding surfaces (first- to fifth-order) and AEs allows the classification of six EAs, which, in this study, are defined as the largest-scale architectural subunits that allow for architectural-based mapping over a large area. EAs delineated in this study are sandy braided-river (EA1), delta-front (EA2), gravelly braided-river to delta-top (EA3), delta-front to lacustrine (EA4), braided-river to deltaic (EA5), and sand-dominated fluvial (EA6). AEA is utilized here to capture three levels of heterogeneity, which allow detailed reservoir characterization based on geometric objects and can be readily used for computer-based modelling. Outcrop analogue studies such as this one provide insight to the geometries of more deeply buried coarse-grained deposits that form potential reservoirs and enhance paleoenvironmental reconstruction of subsurface alluvial deposits in Canada and elsewhere.

Análisis Sedimentológico del Paleolago Jircacocha, Quebrada Cojup, Cordillera Blanca, Perú.

“…This preliminary study is intended to demonstrate the ability of sedimentological and landsystem analyses of valley infill deposits (e.g. Slomka and Eyles 2013;Lee, Maclachlan and Eyles, 2018;Malecki et al, 2018) to enhance understanding of complex depositional histories and the dynamic glacial and non-glacial processes that continue to operate in these environments.…”

Sedimentary architecture of a glaciolacustrine braidplain delta: proxy evidence of a pre‐Middle Wisconsinan glaciation (Grimshaw gravels, Interior Plains, Canada)

“…Interpretation. -The asymmetrical concave-up beds of sand and gravel in FA2 appear similar to the channel elements of Miall (1985) and concave-fill elements of Slomka & Eyles (2013), and probably record various types of channel-fill, including lateral accretion of gravelly bars (Gp facies) and chute channel sandy infill (Sl facies ;Miall 1977a, b); however, commonly only one channel margin is visible in outcrops (Figs 4, S6A). The facies composing FA2 are similar to sediment types previously interpreted by Dawson & Bryant (1987) from glacifluvial deposits, and summarized in the braided river facies model by Miall (1985Miall ( , 2010, to record deposition of gravel bars and macroforms (Gp facies), bedload sheets or longitudinal bars (Gcm facies), and minor channel-fill sediment (Gs facies) including sandy bars (Sp facies) and bedload traction carpets (Sl facies; Table S1).…”

Internal architecture of a till sheet, Tiskilwa Formation, north‐central Illinois, USA: Application of architectural element analysis

“…Boyce & Eyles, ) origin. One of the main components of AEA is the bounding surface hierarchy (based on the degree of environmental change represented at each facies contact; Miall, ), which provides a framework for systematic delineation of sedimentary geometry at various scales of resolution (Miall, ; Heinz & Aigner, ; Slomka & Eyles, ). A six‐tiered bounding surface hierarchy was defined in the present study (Fig.…”

“…Grouping of spatially related and genetically related AEs and their relationship with fifth‐order surfaces served as the basis for delineation of five larger scale architectural units, termed ‘element associations’ (EAs 1 to 5; Fig. ; Slomka & Eyles, ). Element associations are distinguished by their internal architecture and depositional history; hence, they are named using a variable combination of their characteristic architecture (for example, multi‐storey or complex), predominant facies or AE (for example, diamict sheet, DS or lens‐dominated), and depositional processes (for example, glaciotectonite).…”