Abstract

The Cutoff Formation consists of deep water sediments that were shed across the drowned Victorio Peak – Bone Spring margin and Delaware Basin floor during late Leonardian to early Guadalupian time. Here we focus on developing an understanding of how the drowned Late Leonardian (L6) margin influenced the architecture of draping Cutoff strata, with particular emphasis on styles of deposition associated with organic-rich, siliceous, and clay-bearing carbonates.

Following detailed studies of McDaniel and Pray (1967), Harris (1987), and Amerman et al. (2011), we have used a combination of 26 measured sections along with thin sections, TOC and spectral GR profiles, and limited new biostratigraphic data. An extensive digital spatial database for 3D mapping includes: airborne and ground-based lidar, RTK GPS controlled mapped contacts, and 3D photogrammetrically constrained point-clouds. These data are concentrated in the lower slope (Rest Area Gully) through previous shelf break (Shumard Canyon) area, covering approximately 1300 m of section across 7.5 km of the profile. Dip angles vary systematically from the toe-of-slope (<1-4 ^o) to the buried Victorio Peak-Bone Spring shelf margin (4-14^o).

Processes of erosion, bypass, and slope failure initiating at the buried shelf margin are shown here to exert a first-order control on the spatial distribution of facies type and strati-graphic architecture. Limited biostratigraphic zonation in addition to a sequence-by-sequence link to the San Andres shelf system suggests that allocyclic mechanisms exerted an important temporal control on the accumulation of organic matter within the lower slope environment. Advances in the stratigraphic model of the Cutoff Formation presented in this talk may inform the understanding of unconventional reservoirs within the Upper Bone Spring and Avalon trends.