Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Quantified Facies Geometry Within a Mixed Carbonate-Clastic Reef-Rimmed Shelf: High-Resolution Sequence Stratigraphic Architecture of the Yates Formation in Slaughter Canyon, New Mexico
Charles
Harman1; Charles
Kerans1
(1) Jackson School of Geoscience, University of Texas at Austin, Austin, TX.
This study uses excellent outcrops of the Yates Formation in Slaughter Canyon, New Mexico to quantify the paleogeomorphically significant intra-cycle facies dimensional data and covariance of facies geometries with accommodation shifts associated with the composite sequence transition from progradation (Y2-Y4) to aggradation (Y5). Data from approximately 40 mixed carbonate-clastic high-frequency cycles across 4 km of the dip-oriented northeast wall focuses on the shelf crest and outer shelf facies tracts where the greatest potential for reservoir development exists. Facies represented in these tracts include: massive to cross bedded very fine sandstone, teepee-pisoid rudstone, skeletal-peloid fenestral laminite, cross-bedded skeletal-ooid grainstone, cross bedded to massive skeletal-fusulinid rudstone, and massive algal-fusulinid mud-dominated packstone. The location, lateral extent, and vertical thickness of each facies tract is controlled by accommodation conditions and underlying physiography; recent work in the area has also documented numerous syndepositional faults which can also influence facies geometry.
We map facies variability within the meter-scale cycles using a combination of data including: 10 measured sections covering approximately 1000 m of vertical section over 4 km of the dip-oriented east wall, petrography, high-resolution photomosaic mapping, and three-dimensional mapping of bedding onto an airborne lidar DEM of the canyon. Quantitative data on the morphology of key sequence and cycle surfaces from lidar allows accurate 3D reconstruction of the depositional profile and the changing facies architecture in response to changes in the profile. Facies tracts are characterized in terms of dip-width, component facies isopachs, indicator facies offset, paleobathymetry, facies partitioning, fault offset, and the progradation to aggradation ratio.
Systematic changes in above characteristics of the key facies and facies tracts across the progradational to aggradational stack of sequences (Y2-4 vs Y5 respectively) improve our understanding of the response of a complex mixed carbonate-clastic system to allogenic change and can be used as predicative tools in reservoir models.