Annandags Peaks
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The Annandags Peaks () are a group of small, isolated peaks about southwest of the Jule Peaks (Christmas Peaks) in
Queen Maud Land Queen Maud Land ( no, Dronning Maud Land) is a roughly region of Antarctica claimed by Norway as a dependent territory. It borders the claimed British Antarctic Territory 20° west and the Australian Antarctic Territory 45° east. In addit ...
. They were mapped by Norwegian cartographers from surveys and from air photos by the
Norwegian–British–Swedish Antarctic Expedition The Norwegian–British–Swedish Antarctic Expedition (also known as NBSX or NBSAE) (1949–1952) was the first Antarctica expedition involving an international team of scientist A scientist is a person who conducts Scientific method, scienti ...
(1949–52) and named "Annandagstoppane" (
Boxing Day Boxing Day is a holiday celebrated after Christmas Day, occurring on the second day of Christmastide (26 December). Though it originated as a holiday to give gifts to the poor, today Boxing Day is primarily known as a shopping holiday. It ...
's Peaks). The Annadagstoppane granite is the only exposed part of the Archaean basement of the
Grunehogna Craton Vaalbara was an Archean supercontinent consisting of the Kaapvaal Craton (now in eastern South Africa) and the Pilbara Craton (now in north-western Western Australia). E. S. Cheney derived the name from the last four letters of each craton's name ...
and the only Archaean fragment of West
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
(Africa and South America) left in Antarctica. U-Pb dating of the youngest
detrital Detritus (; adj. ''detrital'' ) is particles of rock derived from pre-existing rock through weathering and erosion.Essentials of Geology, 3rd Ed, Stephen Marshak, p G-7 A fragment of detritus is called a clast.Essentials of Geology, 3rd Ed, Stephen ...
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 from Annandagstoppane returned an age of 3067±8 Ma and a tectonic-magmatic history identical to that of the
Kaapvaal Craton The Kaapvaal Craton (centred on Limpopo Province in South Africa), along with the Pilbara Craton of Western Australia, are the only remaining areas of pristine 3.6–2.5 Ga (billion years ago) crust on Earth. Similarities of rock records fro ...
in southern Africa. This suggests that the Kaapvaal-Grunehogna Craton remained stable for 2.5 billion years before it was split by the
Pan-African orogeny The Pan-African orogeny was a series of major Neoproterozoic orogenic events which related to the formation of the supercontinents Gondwana and Pannotia about 600 million years ago. This orogeny is also known as the Pan-Gondwanan or Saldanian Oro ...
. Hafnium dating of
phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...
ic and detrital zircons in the granite revealed several crustal sources up to 3.9 billion years old. This suggests that intracrustal melting and recycling was common in the Mesoarchaean and may be an important process in the initial stabilisation of
continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...
(i.e. the formation of the first
craton A craton (, , or ; from grc-gre, κράτος "strength") is an old and stable part of the continental lithosphere, which consists of Earth's two topmost layers, the crust and the uppermost mantle. Having often survived cycles of merging and ...
s.)


References

Mountains of Queen Maud Land Princess Martha Coast {{PrincessMarthaCoast-geo-stub