Osorno–Llanquihue Basin

The Osorno–Llanquihue Basin (Spanish: Cuenca Osorno-Llanquihue) is a sedimentary basin located in south-central Chile in the forearc region of the Andes. From north to south the basin spans and area from Catamutún to Reloncaví Sound (40–42° S).^[1] The deepest part of the basin lie to the east.^[2] The lower levels of the basin are occupied by coal-bearing Cheuquemó Formation among other units while the Miocene-aged marine Santo Domingo Formation makes up much of the upper stratigraphy.^[2] The uppermost levels are made of sediments of Quaternary age of glacial, glaci-fluvial, glaci-lacustrine and volcanic character.^[3] The thickness of Quaternary sediments is greater to the south reaching almost 1,300 m (4,300 ft) in Puerto Montt.^[3] Sediments in the western part of the basin are roughly estimated to have reached 70 °C (158 °F) during burial and diagenesis.^[4]

Osorno–Llanquihue Basin
Cuenca de Osorno-Llanquihue
SRTM map of the topography of the northern part of Osorno–Llanquihue Basin. The basin does largely correspond with the topographic low of the Chilean Central Valley.
Coordinates	40.712124°S 73.109218°W / -40.712124; -73.109218
Etymology	Osorno and Llanquihue Lake
Location	Southwestern South America
Country	Chile
State(s)	Los Ríos Region Los Lagos Region
Characteristics
On/Offshore	Southern tip is offshore
Boundaries	Chilean Coast Range (W) Andes (E)
Hydrology
Sea(s)	Eastern Pacific Ocean
River(s)	Bueno, Negro, Pilmaiquén, Rahue, Damas
Lake(s)	Llanquihue, Laguna Las Ortigas and the westernmost portions of Rupanco, Puyehue and Ranco
Geology
Basin type	Forearc basin
Orogeny	Andean
Age	Oligocene-Pleistocene
Field(s)	Chilean coal