BackgroundThe Crater Basalt volcanic field lies about 400 km east of the Perú-Chile trench and is related to extension along the broad regional, NW-SE-trending Gastre fault system. The erupted lavas range in composition from alkali basaltic, basanitic, to trachybasaltic.
Radiometric K/Ar ages of lava samples seem to indicate 3 periods of activity: the oldest lava flows were erupted around 1 million years ago (in the center and eastern part of the field, Cerro Ventana, Pinchuleu, Contreras) (1.04 ± 0.43 million years), the second group was active around 600,000 years ago in the central-northern parrt (Cerro Volcán, Fermin). The youngest group (Cerro Antitruz, Negro) was dated around 0.23 ± 0.10 million years ago and forms the western part of the field scoria cone on the Rio Chico-fluvial terrace.
from E to W (old-young):
Cerro Contreras (1004 m) is deeply eroded, only 2 volcanic dikes are well preserved.
Cerro Pinchuleu (1005 m) erupted at least 4 lava flows.
Cerro Ventana (1008 m) is a partially eroded cinder cone. 7 lava flows were fed from this vent.
Cerro Loma Huacha (959 m) is a cinder cone with a small parasitic cone on its northeast flank. Its crater is 50 m wide and breached to the north.
Cerro Fermín (1153 m) is one of the largest cinder cones in the Crater Basalt field large cand produced 6 lava flows. It is composed of spatter, cinder and bombs.
Cerro Volcán (1025 m) is a scoria conewith a 100 m wide and 30 m deep crater.
Cerro Negro (1159 m) is the highest cone of the Crater Basalt volcanic field. It produced at least 4 block lava flows with well-developed channels, which traveled to the west, east, and then NE, where they joined the flows of the Gastre trench near Provincial road 4.
Cerro Antitruz (1100 m) is a pyroclastic cone in the western part of the volcanic field, and is probably the youngest of the group.
- PÉCSKAY et al (2007) "PRELIMINARY K/Ar GEOCHRONOLOGY OF THE CRATER BASALT VOLCANIC FIELD (CBVF), NORTHERN PATAGONIA", Revista de la Asociación Geológica Argentina 62 (1): pp 25-29
- Mena et al (2005) "Paleomagnetism of postglacial beek-arc basalts in Gastre (northwestern
Patagonia)", 6th International Symposium on Andean Geodynamics (ISAG 2005, Barcelona) , Extended Abstracts: 504-507
Crater Basalt Photos
The erupting crater of Yasur volcano under a moon- and starlit sky. The torch of a distant observer on the opposite rim looks like a second moon. (Photo: Tom Pfeiffer)
See also: Sentinel hub | Landsat 8