The Napier Mountains are a group of close set peaks, the highest being

Mount Elkins Mount Elkins, also known as Jökelen (which means "The Glacier") is a dark, steep-sided mountain with three major peaks, the highest above sea level, in the Napier Mountains of Enderby Land. Enderby Land is part of East Antarctica, and is claime ...

, at about 2,300 meters above sea level. This

mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arise ...

is located in

Enderby Land Enderby Land is a projecting landmass of Antarctica. Its shore extends from Shinnan Glacier at about to William Scoresby Bay at , approximately of the earth's longitude. It was first documented in western and eastern literature in February 183 ...

, in the claimed

Australian Antarctic Territory The Australian Antarctic Territory (AAT) is a part of East Antarctica claimed by Australia as an external territory. It is administered by the Australian Antarctic Division, an agency of the federal Department of Climate Change, Energy, the Env ...

, East Antarctica.

Location

The Napier Mountains are roughly four degrees west of

Cape Boothby Cape Boothby is a rounded cape in East Antarctica along the east side of the coastal projection of Edward VIII Plateau. It is north of Kloa Point, just north of Edward VIII Bay. It was discovered on 28 February 1936 by Discovery Investigations ...

Edward VIII Bay Edward VIII Bay is a bay about in extent, located between Edward VIII Plateau (a dome-shaped, ice-covered peninsula near Magnet Bay) and the Øygarden Group of islands in Antarctica. The head of the bay is occupied by the Edward VIII Ice Shel ...

and

Edward VIII Ice Shelf Edward VIII Ice Shelf is an ice shelf occupying the head of Edward VIII Bay in Antarctica. The northern part of this feature was called Innviksletta (the inner bay plain) by Norwegian cartographers, who mapped it from aerial photos taken by the Lars ...

, and 3.5 degrees east of

Amundsen Bay Amundsen Bay, also known as Ice Bay, is a long embayment wide, close west of the Tula Mountains in Enderby Land, Antarctica. The bay was seen as a large pack-filled recession in the coastline by Sir Douglas Mawson on 14 January 1930. Seen by Capta ...

. The Napier Mountains are centered about 64 km south of

Cape Batterbee Cape Batterbee is a small, rocky point on the coast, the most northerly cape of Enderby Land. It is located 92 km north of Mount Elkins. Discovery and naming Cape Batterbee was discovered by BANZARE (1929–31) on 13 January 1930. Named ...

in Enderby Land, East Antarctica. It extends about 64 km in a NW-SE direction from

Mount Codrington Mount Codrington () is a prominent mountain, high, standing south-southeast of Cape Close, east of Johnston Peak, and south of Simmers Peaks. Mount Codrington forms the northeastern end of the Napier Mountains. It was charted in 1930 by the ...

, and also includes

Mount Kjerringa Mount Kjerringa is an isolated peak, above sea level, situated roughly north of the Aker Peaks, west of Magnet Bay, and northeast of Mount Elkins in Enderby Land, East Antarctica. Discovery and naming Mount Kjerringa was mapped by Norwegian ...

, and the

Young Nunataks Young Nunataks () is a group of nunataks in the Napier Mountains standing 2 nautical miles (3.7 km) south of Mount Elkins, Antarctica. Mapped by Norwegian cartographers from aerial photos taken by the Lars Christensen Expedition, 1936–37. ...

Discovery

The Napier Mountains were discovered in January 1930 by the British Australian New Zealand Antarctic Research Expedition (BANZARE) under

Sir Douglas Mawson Sir Douglas Mawson OBE FRS FAA (5 May 1882 – 14 October 1958) was an Australian geologist, Antarctic explorer, and academic. Along with Roald Amundsen, Robert Falcon Scott, and Sir Ernest Shackleton, he was a key expedition leader durin ...

. They were named by Mawson after the Hon. Sir John Mellis Napier, a Judge of the

Supreme Court of South Australia The Supreme Court of South Australia is the superior court of the Australian state of South Australia. The Supreme Court is the highest South Australian court in the Australian court hierarchy. It has unlimited jurisdiction within the state in ...

, 1924–42 and Chief Justice of South Australia, 1942–67. This mountain range was first visited by an

ANARE The Australian National Antarctic Research Expeditions (ANARE ) is the historical name for the Australia: Antarctic Program#Australian Antarctic program, Australian Antarctic Program (AAp) administered for Australia by the Australian Antarctic D ...

party in 1960. Members of this party included Syd Kirkby and Terence James Elkins.

Features

Geographic features of the Napier Mountains include: * Fitzgerald Nunataks *

Grimsley Peaks The Grimsley Peaks () are five linear peaks just south of Stor Hanakken Mountain in the Napier Mountains of Enderby Land, Antarctica. They were mapped by Norwegian cartographers from air photos taken by the Lars Christensen Expedition of 1936–37. ...

Mount Breckinridge Mount Breckinridge is a mountain, high, standing south of Stor Hånakken Mountain in the Napier Mountains of Enderby Land, Antarctica. It was mapped by Norwegian cartographers from aerial photos taken by the Lars Christensen Expedition of 193 ...

Mount Griffiths Mount Griffiths () is an elongated mountain with two prominent peaks of , standing northwest of the Wilkinson Peaks and northwest of Mount Elkins in the Napier Mountains of Enderby Land, Antarctica. Discovery and naming The mountain was plotte ...

Mount Maines Mount Maines, also known as Stornuten, is a mountain, , standing roughly SE of Stor Hånakken Mountain and W of Mount Elkins in the Napier Mountains, Enderby Land. Discovery and naming Mount Maines was mapped by Norwegian cartographers from ai ...

Mount Rabben Mount Rabben () is a mountain, 1,540 m, standing 2 nautical miles (3.7 km) northeast of Mount Griffiths in the Napier Mountains, Enderby Land. It was mapped by Norwegian cartographers from air photos taken by the Lars Christensen Expedition ...

Skorefjell Skorefjell () is a mountain, 1,520 m, standing northeast of Stor Hanakken Mountain in the Napier Mountains in Enderby Land. It was mapped by Norwegian cartographers from air photos taken by the Lars Christensen Expedition Lars is a common ma ...

Stor Hånakken Mountain Stor Hånakken Mountain (also Mount Bennett)14077 Mount Bennett

Wilkinson Peaks The Wilkinson Peaks, also known as Langnabbane, is a group of peaks in the Napier Mountains standing southeast of Mount Griffiths and northeast of Mount Elkins in Enderby Land. Discovery and naming The Wilkinson Peaks were mapped by Norwegian c ...

Geology & orogeny

The Napier Complex is among the most ancient terrestrial

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust (geology), crust fragment formed on a tectonic plate (or broken off from it) and Accretion (geology), accreted or "Suture (geology), sutured" to crust lying on another pla ...

s on Earth. Its evolution is characterized by high-grade

metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

and several strong deformations. At least four distinct tectonothermal events occurred in the Archaean

Eon Eon or Eons may refer to: Time * Aeon, an indefinite long period of time * Eon (geology), a division of the geologic time scale Arts and entertainment Fictional characters * Eon, in the 2007 film '' Ben 10: Race Against Time'' * Eon, in the ...

: # 3.8 billion years ago: occurrence of initial felsic

igneous activity Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a ...

over a long period of time # 3.0 billion years ago: emplacement of

charnockite Charnockite () is any orthopyroxene-bearing quartz-feldspar rock formed at high temperature and pressure, commonly found in granulite facies metamorphic regions, ''sensu stricto'' as an endmember of the charnockite series. Charnockite series Th ...

Proclamation Island Proclamation Island is a small rocky island west of Cape Batterbee and close east of the Aagaard Islands of Antarctica. Historic site The island was discovered by the British Australian New Zealand Antarctic Research Expedition (BANZARE), led by ...

# 2.8 billion years ago: occurrence of a very-high grade discrete tectonothermal event (a UHT metamorphic event) # 2.5 billion years ago: occurrence of a subsequent, protracted high-grade tectonothermal event Much of the

East Antarctic craton The East Antarctic Shield or Craton is a cratonic rock body that covers 10.2 million square kilometers or roughly 73% of the continent of Antarctica. The shield is almost entirely buried by the East Antarctic Ice Sheet that has an average thicknes ...

was formed in the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

period by a series of tectonothermal

orogenic Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumples and is uplifted t ...

events. Napier orogeny formed the cratonic nucleus approximately 4 billion years ago. Mount Elkins is a classic example of Napier orogeny. Napier orogeny is characterized by high-grade

and

plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...

. The orogenic events which resulted in the formation of the Napier Complex (including Mount Elkins) have been dated to the

Archean The Archean Eon ( , also spelled Archaean or Archæan) is the second of four geologic eons of Earth's history, representing the time from . The Archean was preceded by the Hadean Eon and followed by the Proterozoic. The Earth Earth ...

. Radiometrically dated to as old as 3.8 billion years, some of the

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of the r ...

s collected from the orthogneisses of

Mount Sones Mount Sones () is a mountain standing on the north side of Beaver Glacier, two nautical miles (3.7 km) west of Mount Reed in the Tula Mountains in Enderby Land, Antarctica. The mountain was plotted from air photos taken by ANARE ( Australian ...

are among the oldest rock specimens found on Earth. Billions of years of

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

and tectonic deformation have exposed the

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

core of these ancient mountains. The oldest crustal components found to date in the Napier Complex appear to be of

igneous Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or ...

derivation. This rock appears to have been overprinted by an ultra-high temperature metamorphic event (UHT) that occurred near the Archean-Proterozoic boundary. Using a lutetium-hafnium (Lu-Hf) method to examine

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...

, orthopyroxene,

sapphirine Sapphirine is a rare mineral, a silicate of magnesium and aluminium with the chemical formula ( (with iron as a major impurity). Named for its sapphire-like colour, sapphirine is primarily of interest to researchers and collectors: well-formed c ...

osumilite Osumilite is a very rare potassium-sodium-iron-magnesium-aluminium silicate mineral. Osumilite is part of the milarite group (also known as the milarite-osumilite group) of cyclosilicates. Characteristics Osumilite chemical formula is .Don S. ...

and

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer Polymorphism (materials science), polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest ...

from this UHT

granulite Granulites are a class of high-grade metamorphic rocks of the granulite facies that have experienced high-temperature and moderate-pressure metamorphism. They are medium to coarse–grained and mainly composed of feldspars sometimes associated ...

belt, Choi ''et al'' determined an

isochron In the mathematical theory of dynamical systems, an isochron is a set of initial conditions for the system that all lead to the same long-term behaviour. Mathematical isochron An introductory example Consider the ordinary differential equation ...

age of 2.4 billion years for this metamorphic event. Using SHRIMPU–Pb zircon dating methodology, Belyatsky ''et al'' determined the oldest tectonothermal event in the formation of the Napier Complex to have occurred approximately 2.8 billion years ago. Preservation of the UHT mineral assemblage in the analyzed rock suggests rapid cooling, with closure likely to have occurred for the Lu-Hf system at post-peak UHT conditions near a

closure temperature In radiometric dating, closure temperature or blocking temperature refers to the temperature of a system, such as a mineral, at the time given by its radiometric date. In physical terms, the closure temperature is the temperature at which a syste ...

of 800 °C. UHT granulites appear to have evolved in a low Lu-Hf environment, probably formed when the rocks were first extracted from a mantle profoundly depleted in

lithophile element The Goldschmidt classification, developed by Victor Goldschmidt (1888–1947), is a geochemical classification which groups the chemical elements within the Earth according to their preferred host phases into lithophile ( rock-loving), siderophi ...

s. The source materials for the

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

s that formed the Napier Complex were extremely depleted relative to the

chondritic uniform reservoir {{Unreferenced, date=June 2019, bot=noref (GreenC bot) The CHondritic Uniform Reservoir or CHUR is a scientific model in astrophysics and geochemistry for the mean chemical composition of the part of the Solar Nebula from which, during the formati ...

(CHUR). These results also suggest significant depletion of the early Archean mantle, in agreement with the early igneous differentiation of the Earth that the latest core formation models require.

References

External links

Australian Antarctic Names and Medals Committee (AANMC)

Australian Antarctic Gazetteer

United States Geological Survey, Geographic Names Information System (GNIS)

Scientific Committee on Antarctic Research (SCAR)

PDF Map of the Australian Antarctic Territory

Mawson Station
{{usgs-gazetteer Mountain ranges of Enderby Land