From Wikipedia, the free encyclopedia
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 fault takes its name from
Lanalhue Lake
, which is located in part of the fault trace ? the lake's elongated shape shows the NW-SE trend. 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
Valparaiso Region
to Lanalhue Fault, Carboniferous-
Permian
granitoids
make up a large part of the
bedrock
of the Chilean Coast Range. These
igneous rocks
were once part of a proto-Andean
magmatic
belt. South of Lanalhue Fault, most of the Chilean Coast Range is an
accretionary wedge
formed since the
Paleozoic
along the
subduction zone
at South America's western coast.
From a tentative correlation of the fault zone with the similarly NW-SE striking dextral
Jurassic
Gastre Fault System (cf. Rapela & Pankhurst, 1992) in Central
Patagonia
, Argentina, it was termed ‘Gastre Fault Zone’ or ‘Gastre-Puren Fault Zone’. However, in later works
[2]
it is shown that this correlation is incorrect. It was speculated that the inferred
Gastre Fault Zone
aligned
Villarrica
,
Quetrupillan
and
Lanin
volcanoes, until the
Mocha-Villarrica Fault Zone
was discovered.
References
[
edit
]
- ^
Melnick et al 2009, Segmentation of megathrust rupture zones from fore-arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile
- ^
Glodny, J., Echtler, H., Collao, S., Ardiles, M., Buron, P., Figueroa, O. (2008): Differential Late Paleozoic active margin evolution in South-Central Chile (37°S-40°S) -The Lanalhue Fault Zone. - Journal of South American Earth Sciences, 26, 4, 397-411"