Photogrammetric 3D Mapping of the Permian Reef, NM and TX, USA

Although the Permian Capitan depositional system is perhaps one of the best-exposed and most thoroughly studied steep-rimmed carbonate systems, the role of synsedimentary deformation in the development of the platform geometry is still poorly understood. We have undertaken an effort to map 3D stratal and structural architecture in two regions of the Guadalupe Mountains, Slaughter and Big Canyons, to better constrain present-day geometry and quantify the distribution and magnitude of syn- and post-depositional deformation. The resulting 3D geologic models serve to inform and constrain mechanical models aimed at understanding the process of synsedimentary deformation, including formation of early fracture systems that may be important pathways for diagenetic fluids and hydrocarbons.

To construct our 3D model we integrate geologic field mapping, digital photogrammetry, and Global Positioning System (GPS) surveying. Geologic field mapping provides the stratigraphic and structural framework, including quantification of structural densities using scanline methods. Digital photogrammetry is used to convert field interpretations to a 3D structural model with ~1 m precision. GPS surveying (cm to m precision) provides the means to accurately tie field interpretations including key stratal boundaries and structures to the 3D model.

A 2D slice through the model at Slaughter Canyon shows that post-depositional folding is responsible for the majority of structural relief (150-200 m) of upper Yates Formation high frequency sequences. Increasing basinward tilt of strata, a feature that has been variably interpreted as primary depositional dip or as synsedimentary rotation due to differential compaction, generates 50-75 m of additional relief. Finally, synsedimentary faulting is responsible 0-50 m of down-to-the-basin structural relief and smaller amounts of down-to-the-shelf relief. The present-day stratal geometry is thus a composite of possible original depositional effects as well as demonstrably syn and post-sedimentary deformation.