| Fueguino | |
|---|---|
  Fueguino Location of Fueguino in Chile | |
| Highest point | |
| Prominence | 150 m (490 ft) |
| Coordinates | 54°57′S70°15′W / 54.95°S 70.25°W /-54.95; -70.25[1] |
| Geography | |
| Location | Cook,Londonderry Island Tierra del Fuego,Magallanes  Chile |
| Parent range | Tierra del Fuego |
| Geology | |
| Rock age | Miocene-Holocene |
| Mountain type | Volcanic field |
| Volcanic belt | Austral Volcanic Zone |
| Last eruption | 1926 |
Fueguino is avolcanic field inChile. The southernmost volcano in theAndes, it lies onTierra del Fuego's Cook Island and also extends over nearbyLondonderry Island. The field is formed bylava domes,pyroclastic cones, and acrater lake.
Volcanic activity at Fueguino is part of theAustral Volcanic Zone, which is formed by thesubduction of theAntarctic Plate beneath theSouth America Plate. The subducting plate has not reached a depth sufficient for propervolcanic arc volcanism, however.
The field bears no trace ofglacial erosion on its volcanoes, and reports exist of volcanic activity in 1712, 1820 and 1926.
Fueguino volcano lies in thecommune ofCabo de Hornos, Chile.[2] Cities in the region areRio Gallegos,Puerto Natales,Punta Arenas,Rio Grande andUshuaia.[3]
Fueguino is the southernmost volcano in theAndes. The volcano to the north isMonte Burney, which lies 400 kilometres (250 mi) northwest of Fueguino.[1] Both volcanoes belong to theAustral Volcanic Zone.[4] Since thePaleocene, atransform fault, which bisects the island,[5] has been moving the southern part ofTierra del Fuego[6] eastward along theSouth America Plate, accompanied by tectonic uplift that persisted into theHolocene except when it was offset byglacial loading effects.[6]
The subduction of theNazca Plate andAntarctic Plate beneath the South America Plate is responsible for the formation of theAndean Volcanic Belt. This volcanic belt is subdivided into theNorthern Volcanic Zone, theCentral Volcanic Zone, theSouthern Volcanic Zone and the Austral Volcanic Zone. The Austral Volcanic Zone features sixQuaternary volcanoes and is 800 kilometres (500 mi) long. It is separated from the Southern Volcanic Zone by the Patagonian volcanic gap, where arc volcanism ceased 12 million years ago.[4]
South of where theChile Rise intersects thePeru-Chile Trench, the trench disappears as it is increasingly buried by sediments. However,subduction is still active as evidenced by the converging motion of the Antarctic Plate and the South America Plate and the volcanic activity. Only around 52° does the convergence change intostrike-slip faulting at the Shackleton Fracture Zone.[7] Subduction in that area commenced 17 million years ago, and the Antarcticslab has not sunk deep into the mantle. At shallow depth, magma generation is dominated byanatexis of the slab. The mantle ahead of the edge of the subducting slab may be dominated by a largeslab window.[8]
Other volcanic activity occurred in the region farther east, onHardy Peninsula and some surrounding capes and islands during theMiocene;[9]potassium-argon dating has yielded ages of 18 and 21 million years ago. These volcanic systems may indicate that the Antarctic Plate is subducting beneath theScotia Plate.[10]
Three stages of tectonic activity have been noted;Late Cretaceous,Paleocene-Early Eocene andMiddle Eocene toOligocene.[11]
Fueguino lies on a peninsula on the southeastern side ofCook Island, Tierra del Fuego,[1] but it also extends toLondonderry Island. The main Tierra del Fuego island lies northeast of Fueguino.[9] This area of southern Tierra del Fuego is part of theFuegian Andes,[12] which are formed by various intrusive, effusive and metamorphic forms on the Scotia Plate.[13]
The field containslava domes andpyroclastic cones,[1] reaching heights of 150 metres (490 ft).[14]Dikes outcropping about 5 kilometres (3.1 mi) north from the volcanic field may also be genetically related to it.[15] One of these cones has acrater lake within a 150 metres (490 ft) wide crater. Volcanic activity may be influenced by north-south trendingfaults.[1] Unlike many other volcanoes in the Austral Volcanic Zone, Fueguino is not considered to be a source of widespreadtephra deposits.[16]
The field has eruptedandesite.[1] Such a limited range of composition is typical for Austral Volcanic Zone volcanoes, which only feature andesite anddacite.[17] Lava domes featurecolumnar joints.[1] The texture of the rocks istrachytic toporphyritic.[14]
The rocks containphenocrysts ofclinopyroxene,hornblende andplagioclase. In terms of composition, the Fueguino rocks belong to thecalc-alkaline series and resembletholeiites and andesites from primitive volcanic arcs.[14]Xenoliths from the Patagonianbatholith are also found.[17]
The field is formed on top ofplutonic rocks, which were scoured byglaciation.[1] At the south coast of Tierra del Fuego, volcanic activity provided the lateJurassicformation known as theLemaire Formation. Later, during theCretaceous, theYaghan Formation consisting of marine sediments was deposed on top of the Lemaire Formation.[12] The basement of Fueguino consists of anophiolite ofLate Jurassic toEarly Cretaceous age. The ophiolitic sequence containspyrrhotite,chalcopyrite,titanomagnetite,cubanite andpyrite.[18]
The volcanoes were unaffected byglacial activity, and potassium-argon dating has indicated a near absence of radiogenic argon.[14] Myths of theYaghan people of a "world fire" may be a reference to volcanism at Fueguino, but they could also refer to animpact event.[19]
Ships passing in the area reported volcanic activity in 1712 and 1820.[1] The former eruption, dated around 26 November is uncertain.[20] It was reported by French captain Josselin Guardin; the volcano was marked on maps as Volcan San Clemente,[21] after Gardin's ship.[22]
The latter eruption was observed on the 25-26 November by HMSConway captained by Basil Hall,[20][23] and involved the eruption of incandescent material.[1] According to reports it lasted intermittently for the whole morning that day.[23] Avolcanic explosivity index of 2 has been estimated.[20] These volcanic activities were at first assumed to have occurred in the local Andes mountains, but a geological expedition byGiacomo Bove in 1882 found no evidence of a volcano there;[22] the field itself was accidentally discovered by geologists ofSERNAGEOMIN in 1978.[23]
Further activity may have occurred on 3 February 1926, when a ship travelling through the northeastern arm of theBeagle Channel encountered a cloud of ash.[23] Such a cloud may have been transported to the ship's location by southwesterly winds from Fueguino.[24] Most recently,seismic swarms far south ofPuerto Williams in 2018 were associated with Fueguino in the media.[25]
The vegetation of the area belongs to theMagellanic Province,[12] formed by deciduous trees at low altitudes.Peatlands andbogs are widespread.[3] The climate is temperate and cold, with temperatures of about 5 °C (41 °F) and precipitation decreasing northeastward.[3]Sea surface temperatures in theBeagle Channel range 3–10 °C (37–50 °F).[12] The Fuegian Andes are covered by anice sheet with outlet glaciers, although only on the Chilean side.[3]
During theice ages, a substantial ice cap covered the Patagonian and Fuegian Andes.[3] Two stages of glaciation have been identified in southern Tierra del Fuego; four more have been found north of theMagellan Strait.[26] After about 10,000 years ago,Nothofagus woods developed in the region.[27]
