Greenfield Exploration of Hidden Geothermal Magmatic Systems by Fluid Chemistry - Case Study Lamongan / East Java

Geothermal resources belong to alternative geoenergy systems where heat and electricity can be produced in a sustainable way with no or low climate gas emissions. Magmatic geothermal systems are potential candidates for economic use due to high temperature and pressure of produced fluids. Indonesia is one of the areas with the highest geothermal potential worldwide. However, greenfield exploration in tropical areas with steep terrain is challenging, especially if geothermal systems are hidden with no obvious surface manifestations. In our study from the Lamongan volcanic areas in East Java we demonstrate an approach of greenfield exploration by fluid chemistry sampling, regional structural geology and petrological analysis. Our results indicate infiltration of seawater through faults from the 20 km nearby coast and a possible heat source in about 3-5 km. The obviously presence of large amounts of fluids indicate a medium temperature geothermal resource. Shallow temperature drilling would clarify the quantity of producible geothermal energy. Our study demonstrates how green field exploration can be started to develop further site specific exploration strategies for hidden geothermal systems in tropical regions.