The Caicos Platform — A Valuable Modern Analog for Understanding Facies Patterns of Subsurface Isolated Platforms
Paul M. Harris1 and James Ellis2
1Chevron Energy Technology Company, San Ramon, CA
2Ellis GeoSpatial, Walnut Creek, CA
The Caicos Platform has proven to be an area of continuing interest to researchers of modern carbonates, an important training venue, and a valuable modern analog for understanding facies patterns of subsurface isolated platforms. We hope to promote this interest by making readily available a set of processed satellite images and an offshore/onshore digital elevation model (DEM), along with examples of how this data can be visualized and used.
The clearest satellite images of Caicos Platform from 1972 to 2005 were acquired and processed. Image processing was undertaken to maximize apparent water penetration and delineate submerged features. The primary images are 30-m Landsat TM complemented by older 57-m Landsat MSS, 15-m ASTER, and 0.6 m Quickbird. The processed scenes were georeferenced to a base image in GIS, creating a stack of co-registered images. Masks were created for water and land to enable integration of different images and maps. Soundings, together with estimated water depths based on the spectral characteristics of a Landsat TM image from earlier work, were used to create a digital bathymetric map. This offshore depth map was integrated with an onshore DEM derived from NASA Space Shuttle elevation data (SRTM) for the islands. Various satellite images and maps can be draped on the DEM within the GIS to provide perspective views.
To increase accessibility, improve learning, and promote spatially accurate feedback, the stack of images, color-coded DEM, and geologic maps were exported out of GIS using TerraGo’s GeoPDF for viewing with free Adobe Acrobat. Users of these GeoPDFs can annotate and interpret features, and then export their maps (points, lines, and polygons) as shapefiles for loading into a GIS. In addition, GIS layers were imported into GoogleEarth for global distribution and display as kmz files.
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