Climate as a Stratigraphic Tool for Basin Margin Deposition in Intracontinental Basins

Alluvial development during climate fluctuations depicted with spectral decomposition of the Middle Triassic to Lower Jurassic post‐rift succession in the Horda Platform (Norway) and the impact on reservoir properties

“…The proximal parts of fans consist largely of deep incised channels that form pathways for fluvial streams and debris flows, and host coarse, immature channel infill successions (Jo et al, 1997; Würtzen et al, 2022). With distality on a fan, decreasing flow competence results in a decrease in channel width and depth, resulting in a transition from braided patterns in the proximal domain to increased channel sinuosity and finer grain deposits in distal settings (Gough, 2015; Luzon, 2005; Moscariello, 2018).…”

“…The medial fan zone represents the transition between the debris flow‐dominated proximal/inner fan zone and the distal fan zone dominated by shifting fluvial streams (Blair & McPherson, 2009). Gough (2015) described the deposits of a medial fan as characterized by inter‐bedded immature deposits of rapidly accreting, small‐scale bars of braided streams, topped by rooted horizons, fining‐upwards sandy sheet flood deposits, thick debris flow conglomerates of varying maturity and clast sizes and occasional clast‐supported sieve deposits. These facies are typical of fans of arid continental basins, whereas fans of humid environments tend to be increasingly dominated by fluvial processes, as run‐off expectedly is higher (Moscariello, 2018).…”

“…Here, in such a sedimentary setting, deposits of shallow, high‐sinuous channels, crevasse splays, and sheet flows of very fine to coarse‐grained sandstones can be expected to dominate (Blair & McPherson, 2009; Würtzen et al, 2022). Sand‐rich channel deposits will be thicker, with more prominent side (point) bar deposits, compared to those of the medial fan (Gough, 2015). The distal channel fills have higher textural maturity and better sorting than the proximal ones, but also more complex reservoir geometries due to increased heterogeneity of medium‐ to small‐scale sedimentary structures (Moscariello, 2018).…”

“…The prograding to the retrograding trend of the Upper Triassic fan bodies may cause complexity to the reservoir properties but also potential to increase reservoir volume to the target, as the distal fan facies interconnect upwards with basinal facies belts, such as fluvial, lacustrine and aeolian facies (Moscariello, 2018). Overall, a sheet‐like reservoir body geometry may be expected at the wellbore site, with low‐to‐mediate connectivity and a mediate‐ to high facies heterogeneity (Gough, 2015). The connectivity may increase east towards the margin, along with an increased homogeneity, as fewer overbank deposits preserve in proximal settings (Gough, 2015; Würtzen et al, 2022).…”

“…Overall, a sheet‐like reservoir body geometry may be expected at the wellbore site, with low‐to‐mediate connectivity and a mediate‐ to high facies heterogeneity (Gough, 2015). The connectivity may increase east towards the margin, along with an increased homogeneity, as fewer overbank deposits preserve in proximal settings (Gough, 2015; Würtzen et al, 2022).…”