--> Abstract: A Simple GIS Approach to Interpolating Stratigraphic Contact Data for Palaeogeography: Deriving Palaeolandscape Models of the Palaeozoic-Cretaceous Boundary and Subsequent Cretaceous Islands in Central Texas, by Shane J. Prochnow; #90078 (2008)

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A Simple GIS Approach to Interpolating Stratigraphic Contact Data for Palaeogeography: Deriving Palaeolandscape Models of the Palaeozoic-Cretaceous Boundary and Subsequent Cretaceous Islands in Central Texas

Shane J. Prochnow
Geology, Baylor University, Waco, TX

This research uses raster GIS technology to interpolate palaeo-digital terrain models (DTM) within a roughly 4,200 km2 study area in south central Texas. Only readily available geospatial data were used. High-resolution geological maps (1:24,000 and 1:31,600 scale) published by the Bureau of Economic Geology at the University of Texas at Austin were digitized and georeferenced using ArcGIS® software products. Palaeosurface modeling focused on three key stratigraphic boundaries at and just above the Palaeozoic-Cretaceous boundary. Stratigraphic contact traces between these surfaces were converted to three dimensional (3D) data by extracting elevation values from 28 m resolution modern digital elevation models (DEM) using ArcGIS® 3D Analyst. ArcGIS® Geostatistical Analyst was then used to interpolate palaeo-digital elevation models (PDEM) using a spherical Krieging method based upon 12 nearest points along contact traces and their respective elevation values. The interpolated PDEMs have estimated vertical root mean square and standard error within 5 m, roughly the same as the published DEM accuracy used for the derivation of elevation. Thickness maps were verified by using measured section data. The palaeotopography at the Palaeozoic-Cretaceous boundary was comparable in total relief and slope as the modern topography of the study area. The fluvial Hensel Fm is locally absent on palaeohighlands (interfluves) of Palaeozoic rock. Areas of null thickness for the subsequent Glen Rose Fm indicate terrestrial exposure as islands that persisted throughout the deposition of this first marine unit of the Zuni transgression. This study demonstrates how raster GIS modeling can be used in particular with stratigraphic and palaeogeographic studies by spatially interpolating known data into buried, obscured, or eroded areas.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas