Physical controls on carbonate shelf profiles: an example from the Permian Seven Rivers Formation, NM
Abstract
Stratal geometries in shelf-top carbonates contain a record of past eustatic, tectonic, ecological, and oceanographic changes. Physically, carbonate shorelines share similar controls with siliciclastic shorelines, but there are two unique considerations. Firstly, early cementation leads to brittle behavior, and shelf-top geometries are often modified by early faulting and fracturing. Secondly, the shelf margin in carbonate systems is often sub-vertical, creating a discontinuity in the shelf-to-basin sediment transport. This bypass surface imposes a strong boundary condition on the downstream end of the shelf-top profile. Together, brittle deformation and the sediment transport discontinuity allow for significant changes in the shelf-top profile due to intrinsic factors. By understanding and quantifying the effects of these intrinsic factors, we can better separate them from external factors (e.g., eustacy) that affect shelf-top strata.
This study examines the effects of structural deformation and sediment transport conditions on shelf-top strata of the Permian Seven Rivers Formation in McKittrick Canyon, New Mexico. Traditional field mapping and a digital outcrop model compiled from airborne lidar allow quantitative assessments of the relationships among facies, structures, and stratal geometries. Results indicate that there are at least two origins for variations in stratal architecture in the Seven Rivers, including (1) primary dips associated with steepening of the bathymetric profile towards the shelf edge and (2) both landward and seaward rotation of fault blocks during deposition of successively younger strata. We use experimental and numerical methods to model how shoreline profiles evolve as they prograde towards the shelf-margin. Lastly, we explore the implications of our work for understanding the controls on overall platform geometries and trajectories through time.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP52A..01S
- Keywords:
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- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 1051 Sedimentary geochemistry;
- GEOCHEMISTRYDE: 3675 Sedimentary petrology;
- MINERALOGY AND PETROLOGYDE: 4863 Sedimentation;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL