Lanalhue Fault is a northwest-striking fault that marks the contact between two distinct units of continental basement, the Eastern and Western Series in south-central Chile, separating the Nahuelbuta Range Cordillera de Nahuelbuta to the east and the Arauco Peninsula and Basin to the west.
The Lanalhue Fault is a major lithological boundary in the Chilean Coast Range to which Cordillera de Nahuelbuta belongs.
The Nahuelbuta Range is composed by Carboniferous granitic core bounded by high-temperature metasedimentary rocks referred as the Eastern Series.
The Arauco Basin contains over 3 km of Late Cretaceous to Holocene continental and marine sediments, being a major center of coal mining and hydrocarbon exploration for over a century.
[1] From Valparaíso Region to Lanalhue Fault, Carboniferous-Permian granitoids make up a large part of the bedrock of the Chilean Coast Range.