Geometric and Spatial Analysis of Wing-Like Intrusions as Outcrop Analogues for Subsurface Analysis

Wing-like intrusions are some of the most prominent architectural elements identified within subsurface sand injectite complexes. These structures are composed of discordant inner wing zones and bedding-concordant outer wing zones, which can crosscut hundreds of metres of stratigraphy and extend laterally for several kilometres. Their large-scale geometry makes them discernible on seismic data; however, the inability to detect associated smaller intrusions can lead to underestimates of their significance within a basin. To support subsurface analysis, this study integrates field and digital mapping analyses of two wing complex outcrops from two giant injection complexes of the San Joaquin Basin. The Dosados Canyon wing, of the Panoche Giant Injection Complex (PGIC), features a single 14 m thick stepped inner intrusion that bifurcates into outer sills. The wing extends laterally over 1.5 km, crosscutting ca. 300 m of mudstones. Up to 64% of the sandstones are associated with sub-seismic intrusions (< 3 m thickness). The Tumey Hill wing within the Tumey Giant Injection Complex (TGIC) intrudes vertically > 200 m of mudstones and extends laterally for at least 1.3 km. It comprises laterally stacked inner intrusions (up to 12 m thick) transitioning to a highly connected outer sill zone. A total of 225 intrusions (0.15 m to 8 m thick) are identified within the composite wing structure, adding sand volume and providing excellent connectivity. Comparison with the Volund and Varadero fields within the North Sea reveals intrusions with similar scale and geometry, underscoring the value of the outcrops as analogues for characterisation of subsurface reservoirs and to aid the understanding of sand intrusion formation within different basin settings.