Английская Википедия:Curtis Island (New Zealand)

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Шаблон:Short description Шаблон:EngvarB Шаблон:Use dmy dates Шаблон:Infobox islands Curtis Island is an island in the southwest Pacific. It is a volcanic island which, together with neighbouring Cheeseman Island, belongs to the Kermadec Islands, an outlying island group of New Zealand. It is a volcanic island with a fumarolically active crater, while vegetated slopes are nested by seabirds. There are uncertain reports of eruptions and the island has been uplifted by about Шаблон:Cvt during the past 200 years.

History

Lieutenant John Watts, RN was the first European to visit the Macauley and Curtis Islands – which he named after patrons George Mackenzie Macaulay and William Curtis – on the Lady Penrhyn on 1 July 1788.[1]Шаблон:Sfn In 1888 castaway depots were established on both Curtis and Cheeseman islands, for the use of shipwrecked crews.Шаблон:Sfn

Count von Luckner, commander of the German raider Seeadler during the First World War, stopped off at Curtis Island in 1917 to replenish his stores from the castaway depot while attempting to make good his escape from New Zealand to South America.Шаблон:Sfn

Geography and geomorphology

Curtis Island lies in the Kermadec Islands, between Tonga in the north and New Zealand in the south.Шаблон:Sfn The four other islands are Raoul Island and Macauley Island Шаблон:Cvt north of Curtis, Cheeseman Island next to Curtis and L'Esperance Шаблон:Cvt to its south.Шаблон:Sfn Cheeseman Island lies west-northwest from Curtis and is separated from the latter by the less than Шаблон:Cvt wide Stella Passage.Шаблон:Sfn

The island has a surface area of Шаблон:Cvt.Шаблон:SfnШаблон:Sfn Cliffs surround a central plateau at about Шаблон:Cvt elevationШаблон:Sfn and on the northeastern side continue below sea level.Шаблон:Sfn There are no known beaches.Шаблон:Sfn Two gaps in the cliffs are The Chasm to the southeastШаблон:Sfn and former Macdonald Cove to the northwest. The island lies at the western side of a Шаблон:Cvt wide shoal at less than Шаблон:Cvt depth on the Kermadec Ridge.Шаблон:Sfn Bouldery reefs occur at Шаблон:Cvt depth.Шаблон:Sfn The total volume of the volcano, including its submarine sector, is about Шаблон:Cvt,Шаблон:Sfn and it features a Шаблон:Convert wide caldera. The deepest point of the caldera is Шаблон:Convert below sea level.Шаблон:Sfn

At the centre of the island, slightly offset to the northwest,Шаблон:Sfn lies a Шаблон:Cvt deep,Шаблон:Sfn elliptical, maximally Шаблон:Cvt wide volcanic crater with a surface area of Шаблон:CvtШаблон:Sfn at Шаблон:Cvt above sea level.Шаблон:Sfn North-south trending fractures in the island appear to have influenced the formation and shape of the crater.Шаблон:Sfn There is a breach on the northern sideШаблон:Sfn and a warm stream drains the craterШаблон:Sfn into the sea northwest of the island.Шаблон:Sfn A second crater is found on the southeastern side of the island.Шаблон:Sfn This highest elevation is Шаблон:Cvt.Шаблон:Sfn

Geology

The Шаблон:Cvt long Tonga-Kermadec arc extends from New Zealand's North Island to TongaШаблон:Sfn and lies between the Havre Trough to the west and the Kermadec Trench to the east.Шаблон:Sfn It occurs where the Pacific Plate subducts beneath the Australian PlateШаблон:Sfn in the Kermadec TrenchШаблон:Sfn giving rise to magmas from depleted mantle with minor quantities of melted sediments that drive volcanism.Шаблон:Sfn Generally, the geology of the Kermadec arc is poorly known, as most of it is submerged.Шаблон:Sfn The emergent parts form the Kermadec Islands.Шаблон:Sfn

The Havre Trough is a backarc basinШаблон:Sfn where crustal spreading takes place;Шаблон:Sfn it is the southern continuation of the Lau basinШаблон:Sfn where seafloor spreading is underwayШаблон:Sfn and the entire system formed due to a southwestward movement of the Kermadec arc.Шаблон:Sfn Of the volcanoes in the Kermadec arc, Raoul Island has had historical eruptions and active submarine volcanoes have been discovered.Шаблон:Sfn

Composition

Most of the island is formed by pyroclastic rocks,Шаблон:Sfn which in some places are intruded by dykes. The pyroclastic rocks are mainly tuff-like, with embedded pumice and rock fragments and only weak bedding.Шаблон:Sfn Volcanic rocks from Curtis Island include andesiteШаблон:Sfn with plagioclase and pyroxene phenocrysts.Шаблон:Sfn Dacites have also been reported, while there are no reported mafic rocks.Шаблон:Sfn

Hydrothermal deposits such as silicaШаблон:Sfn and sulfur occur in the crater.Шаблон:Sfn Hydrothermal alteration by hydrothermal waters and the condensation of sulfuric acidШаблон:Sfn has yielded aluminite, alunite, anhydrite, chlorite, cristobalite, diaspore, gibbsite, hematite, kaolinite, metahalloysite, natroalunite, pyrite, quartz and smectite, with chlorite, diaspore, natroalunite and sulfur being the most common.Шаблон:Sfn

Biology

Like the other Kermadec islands, Curtis Island is a nature reserve administered by the New Zealand Department of Conservation.Шаблон:Sfn Ice plant, herbs, grasses and sedges grow on the island,Шаблон:Sfn with species including Asplenium obtusatum, Cyperus ustulatus, Disphyma australe, Lachnagrostis littoralis, Parietaria debilis, Solanum nigrum and Sonchus kirkii although the crater floor is mostly bare.Шаблон:Sfn Boobies, grey ternlets and petrels nest on the island,Шаблон:Sfn which has been greatly impacted by their presence;Шаблон:Sfn the island's soil is heavily burrowed from their nests.Шаблон:Sfn Other birds reported from Curtis Island are blackbirds, starlings and song thrushes,Шаблон:Sfn while there are no known mammals;Шаблон:Sfn goats liberated on it in 1887 did not survive.Шаблон:Sfn Sea life is related to tropical and subtropical animals.Шаблон:Sfn

Eruption history

Curtis Island is believed to be a remnant of a pyroclastic flow sheetШаблон:Sfn or of an andesitic volcano that once included Cheeseman Island, before erosion and sea level changes gave the islands their present shape.Шаблон:Sfn A ship sailing close to Curtis Island in 1936 reported discoloured water in the area, although its position is not known with certainty.Шаблон:Sfn Earthquakes and earthquake swarms recorded around Curtis Island in January and February 2009 may indicate ongoing magma movement underground.Шаблон:Sfn Reports of an eruption in 1869, 1870Шаблон:Sfn or 1899 appear to be incorrect, a December 1936 eruption is uncertainШаблон:Sfn and some reports of eruptions may instead reflect increases in fumarolic activity.Шаблон:Sfn Earthquakes at Curtis in 2009 and 2017 caused tsunamis; they may be due to collapses in the caldera.Шаблон:Sfn

Uplift

Numerous lines of evidence such as a shallowing of the surrounding seaШаблон:Sfn and the emergence of previously submarine rock features such as barnacles and wave-cut notchesШаблон:Sfn indicate thatШаблон:Sfn during the 20th century, the island has risen at a rate of Шаблон:Cvt.Шаблон:Sfn The total uplift between 1929 and 1964 reached Шаблон:CvtШаблон:Sfn and Шаблон:Cvt during the past 200 years.Шаблон:Sfn Since Curtis and Cheeseman are located in the middle of the caldera, they might be resurgent domes that are actively uplifting.Шаблон:Sfn

There appear to have been two distinct uplift episodes with a stillstand from 1908 or earlier to 1929,Шаблон:Sfn and there is evidence for such uplift also at L'Esperance farther south.Шаблон:Sfn Prior to the uplift, Macdonald Cove could be used as a boat landingШаблон:Sfn at least until 1929;Шаблон:Sfn presently Macdonald Cove is dry.Шаблон:Sfn

Hydrothermal activity

Fumaroles,Шаблон:Sfn hot springs and bubbling mud pools occur on the crater floor, with fumarolic gas emissions also recorded elsewhere on the island.Шаблон:Sfn Some pools have temperatures reaching Шаблон:Cvt.Шаблон:Sfn Activity was already noted in the 19th centuryШаблон:Sfn and was rather intense during various landingsШаблон:Sfn but appears to have declined during the 20th century.Шаблон:Sfn

The hydrothermal waters are sulfatic, presumably from the oxidation of hydrogen sulfide, and mainly heated by steam.Шаблон:Sfn They contain aluminum and iron derived from the leaching of rock.Шаблон:Sfn The water appears to originate from the condensation of steam derived from rain and from magma.Шаблон:Sfn

A second, submarine hydrothermal field is the Vulkanolog field Шаблон:Cvt south of Curtis Island.Шаблон:Sfn It was discovered in 1979 by the Шаблон:ShipШаблон:Sfn and named after it,Шаблон:Sfn but its activity appears to have ceasedШаблон:Sfn and it cannot be definitively correlated with Curtis Island.Шаблон:Sfn

See also

Шаблон:Portal

References

Шаблон:Reflist

Sources

Шаблон:Refbegin

Шаблон:Refend

External links

Шаблон:Commons category

Шаблон:Kermadec Islands

Шаблон:Authority control

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  1. ↑ Шаблон:Citation
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