by Jean-Paul van Gestel, 2000
University of Texas PhD dissertation

Abstract
The Puerto Rico-Virgin Islands platform was deposited from early Oligocene to Holocene on top of an inactive and subsiding Cretaceous-earliest Oligocene island arc. Regional single- and multi-channel seismic reflection lines presented in this study provide the first information on the regional stratigraphy and structure of this platform. Integration of seismic reflection, well, and outcrop data indicates three major tectonic phases. The first tectonic phase consists of Cretaceous to Eocene formation and sedimentary infilling of a forearc basin. During the second tectonic phase from Oligocene to Pliocene the ∼1600-m-thick, northward-thickening Puerto Rico-Virgin Islands platform was formed. In the final tectonic phase, from Pliocene to Holocene, the Puerto Rico-Virgin Islands platform tilted northward, whereby the northern edge of the platform submerged to a depth of 4 km. This tilting occurred on the northern limb of a large arch formed parallel to the long axis of the island of Puerto Rico. The arch formed in response to a post-Pliocene convergence between the North America and Caribbean plates. Traditionally Ground Penetrating Radar measurements are conducted using two co-polarized antennas oriented perpendicular to the line of data collection. Configurations, where the antennas are rotated to the line of data collection or are held cross-polarized, are rarely used. In this study it is shown that collection of this kind of data can be used in several methods to improve the final radargram. By recording the reflected field using four different configurations, and applying Alford rotation, information can be extracted about the orientation of objects that have angle-dependent reflectivity. Combination of Ground Penetrating Radar data collected in different polarized configurations using a weighted migration approach does not only improve the signal to noise ratio of the final image, but also results in a more uniform distribution of the radiated energy in the target zone. Alford rotation can also be implemented in a faster and more accurate migration algorithm. All these methods are proven to work on synthetic Ground Penetrating Radar data. They are also successfully applied on field data collected at a controlled Ground Penetrating Radar testing site in Scheveningen, The Netherlands.

University Microfilms International - http://wwwlib.umi.com/dissertations/gateway