Application of holocene geological data for siting coastal nuclear power plants: An example from Puerto Rico

Abstract

Geological and geophysical investigations for a nuclear power plant (NORCO) on the north-central coast of Puerto Rico indicate that the proposed site is structurally suitable and free of late Quaternary faults. However, conflicting interpretation of erosional geomorphic features, primarily nips, terraces and caves cut in coastal eolianities and jointed Tertiary carbonates a few to 10 m above sea level, suggest the possibility of non-fault related epeirogeny as young as Holocene in age. Seven peat samples cored from Cienaga Tiburones, a coastal marsh within the site area, and three wood samples from near-coast fluvial sediments at Arecibo and San Juan, yielded radiocarbon dates ranging in age from about 1,200 to 8,700 years BP. The age and depth associations of these dated sediments fall within or slightly below an envelope defining the maximum oscillatory points of 15 world-wide, Holocene sea level curves. The relationship of the Puerto Rico and world-wide curves suggests no measurable epeirogenic uplift of the north-central coast for at least the last 10,000 years. Coastal caves and terraces above present sea level thus owe their origin to pre-Holocene high stands, or to cave collapse, storm surge, and other modern processes capable of producing erosional features above present tidal range. The analysis of Holocene geological data for north-central Puerto Rico may be a useful technique applicable for siting coastal nuclear power plants elsewhere in the world.