| Title | A Recently Discovered Granitoid Rich Lithic Basal Horizon in the Liberia Formation and Its Possible Implications on Source Vent Location and the Evolution History of a Geothermal Reservoir at the Las Pailas Geothermal Field, Guanacaste, Costa Rica |
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| Authors | Edward Charles Hakanson |
| Year | 2010 |
| Conference | World Geothermal Congress |
| Keywords | Liberia Formation, Granitoid Lithic Fragments, Las Pailas Geothermal Field, Guanacaste, Costa Rica |
| Abstract | The Liberia Formation is a Pleistocene rhyolitic biotite and quartz bearing pumiceous tuff used as a marker bed at the Las Pailas Geothermal well field. A recently discovered outcrop at the base of the Liberia Formation is a granitoid bearing horizon restricted to a 2 meter thick bed. at Las Parcelas de Santa María, Guanacaste, Costa Rica and may provide evidence for proximity to the source vent that produced the Liberia Formation as well as the implications that it may have had during the evolution of the geothermal reservoir at the Las Pailas Geothermal Field. The Liberia Formation crops out at the outer perimeter of the Las Pailas Geothermal Field and to date there are no known outcrops of this formation within the field itself. However, at depth a rock layer has been correlated with the Liberia Formation. Nonetheless, the actual source vent of the Liberia Formation has still not been fully identified, although careful mapping of the spatial and modal distribution of granitoid lithic fragments in this basal bed may provide useful clues as to its location. This report presents the findings of this investigation and conclusions on the possible location of the source vent of the Liberia Formation and the implications that this may have with regard to the evolution of the geothermal reservoir at the Las Pailas Geothermal Field. |