Caldera Basin (
Spanish:
Cuenca de Caldera) is a
sedimentary basin located in the coast of northern
Chile west of
Copiapó. The basin has a fill of marine sediments of
Late Cenozoic age. With a north-south extension of 43 kilometres (27 mi) and an east-west width of 20 kilometres (12 mi) the basin occupies an area between the coast and the
Chilean Coast Range and between the port of
Caldera and the mouth of
Copiapó River. The sedimentary fill rests on
metamorphic rocks of
Paleozoic age and on
plutonic rocks of
Mesozoic age.
Stratigraphy
The following units make up the sedimentary fill
Name |
Age |
Lithologies |
Depositional environment
|
Caldera Beds |
Pleistocene |
|
|
Bahía Inglesa Formation |
Quebrada Blanca |
Late Miocene |
Conglomerate, sandstone, biocalcirudite |
Shoreface, outer shelf, tsunami
|
Rocas Negras |
Calcirudite, biocalciarenite |
Shoreface
|
Mina Fosforita |
Sandstone, siltstone, shale |
Uppermost continental slope, shoreface
|
Chorrillos |
Clast-supported conglomerate |
Submarine canyon debris flow fill, formed possibly by a tsunami
|
La Higera |
Shale with gypsum veins, sandstone, siltstone, diatomaceous clay |
Outer shelf or uppermost continental slope
|
Cerro Ballena |
Silty sandstone |
Supratidal flat
|
Punta Totoral |
Biocalcarenite, biocalcirudite, matrix-supported conglomerate |
Rapid sea-level oscillations
|
Puerto Viejo |
Sandstone, siltstone, claystone, shale, microcoquina |
Shoreface, marine transgression
|
El Pimiento |
Biocalcarenite, quartzarenite |
Shoreface
|
Angostura Formation |
Early to Mid-Miocene |
Matrix-supported conglomerate |
High-energy river mouth
|