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Torlesse Composite Terrane

March 11, 2023

The Torlesse Composite Terrane is a plate tectonic terrane forming part of the South Island of New Zealand. It contains the Rakaia, Aspiring and Pahau Terranes and the Esk Head Belt.[1] Greywacke (or Torlesse Greywacke) is the dominant rock type of the composite terrane; argillite is less common and there are minor basalt occurrences. The Torlesse Composite Terrane is found east of the Alpine Fault in the Southern Alps of New Zealand. Its southern extent is a cryptic boundary with the Caples Terrane within the Haast Schists in Central Otago.[2] It is named for the Torlesse Range in Canterbury.

Torlesse Composite Terrane
Stratigraphic range: Carboniferous-Cretaceous
~320–130 Ma
View of Torless Composite Terrane at Aoraki / Mount Cook
TypeTerrane
Unit ofAustral Superprovince
Sub-unitsKaweka, Rakaia & Pahau Terranes, Esk Head Belt, Pahaoa & Clent Hills Groups
UnderliesCaples Terrane, Momotu, Waka & Haerenga Supergroups
Lithology
PrimaryGreywacke, schist, basalt
Location
RegionCanterbury, Marlborough & Otago Regions
CountryNew Zealand
Type section
Named forTorlesse Range

Cross-section of New Zealand's stratigraphy

Description

The Rakaia Terrane rocks, of Permian to late Triassic age (300–200 Ma), occur south of Rangiora. The Pahau Terrane rocks, of Late Jurassic to Early Cretaceous age (160–100 Ma), occur to the north, and are probably derived from the Rakaia Terrane. At the boundary between these two terranes is the Esk Head Belt, an 11-kilometre (6.8 mi) wide mélange of broken and deformed rocks. The Aspiring Terrane (Aspiring Lithologic Association) is officially included within the Torlesse Composite Terrane; however, it has a higher proportion of igneous rocks and a different sedimentary source.[3] Its original relationship with the Rakaia Terrane is obscured by the Haast Schist.

Deposition

The greywacke of the Torlesse Composite Terrane was deposited on the eastern side of New Zealand from the Late Carboniferous through to the Middle Cretaceous. It was deposited in giant deep sea fans that extended beyond the ends of ancient submarine canyons. A fan starts with a submarine canyon on the continental shelf. Then turbidity currents rush down the canyon like giant undersea avalanches. They carry all sorts of sediments from the shallower seafloor of the continental shelf. At the end of the canyon the turbidity current spreads out and creates giant fans of sediment that blanket the deep seafloor. These sediments may have derived in part from the granitic rocks of northeastern Australia, as suggested by studies of the mineral grains.[4]

Metamorphism

The Torlesse Composite Terrane has undergone metamorphism and been transformed into Haast Schist. In the Haast Schists, the minerals that make up greywacke became coarser grained and altered to other minerals including quartz, feldspar and biotite.[5] Rare pods of pounamu (jade) are found in the higher metamorphic grades near the Alpine Fault.[6]

Fossil content

See also

References

  1. ^ "New Zealand Stratigraphic Lexicon". GNS Science.
  2. ^ "New Zealand Geology: an illustrated guide" (PDF). www.geotrips.org.nz.
  3. ^ Jugum, D; Norris, RH; Palin, JM (2013). "Late Jurassic detrital zircons from the Haast Schist and their implications for New Zealand terrane assembly and metamorphism". New Zealand Journal of Geology and Geophysics. 56 (4): 223–228. doi:10.1080/00288306.2013.815639. ISSN 0028-8306. S2CID 128551272.
  4. ^ "Building a continent".
  5. ^ "The Geology of New Zealand: Greywacke". www.gns.cri.nz. GNS Science.
  6. ^ Cooper, Alan F.; Ireland, Trevor R. (2015). "The Pounamu terrane, a new Cretaceous exotic terrane within the Alpine Schist, New Zealand; tectonically emplaced, deformed and metamorphosed during collision of the LIP Hikurangi Plateau with Zealandia". Gondwana Research. 27 (3): 1255–1269. Bibcode:2015GondR..27.1255C. doi:10.1016/j.gr.2013.11.011. ISSN 1342-937X.
  7. ^ https://paperspast.natlib.govt.nz/periodicals/TRSGEO19650722.2.2
  8. ^ https://paperspast.natlib.govt.nz/periodicals/TRSGEO19650722.2.2
  9. ^ https://icebergdb.com/hectors-ichthyosaurtrue-organism-size-parameters-2/
  10. ^ https://sci.waikato.ac.nz/evolution/FossilEvidence.shtml
  11. ^ https://teara.govt.nz/en/fossils/page-2

Further reading

  • The Rise and Fall of the Southern Alps, G. Coates published 2002

March 11, 2023
torlesse, composite, terrane, plate, tectonic, terrane, forming, part, south, island, zealand, contains, rakaia, aspiring, pahau, terranes, head, belt, greywacke, torlesse, greywacke, dominant, rock, type, composite, terrane, argillite, less, common, there, mi. The Torlesse Composite Terrane is a plate tectonic terrane forming part of the South Island of New Zealand It contains the Rakaia Aspiring and Pahau Terranes and the Esk Head Belt 1 Greywacke or Torlesse Greywacke is the dominant rock type of the composite terrane argillite is less common and there are minor basalt occurrences The Torlesse Composite Terrane is found east of the Alpine Fault in the Southern Alps of New Zealand Its southern extent is a cryptic boundary with the Caples Terrane within the Haast Schists in Central Otago 2 It is named for the Torlesse Range in Canterbury Torlesse Composite TerraneStratigraphic range Carboniferous Cretaceous 320 130 Ma PreꞒ Ꞓ O S D C P T J K Pg NView of Torless Composite Terrane at Aoraki Mount CookTypeTerraneUnit ofAustral SuperprovinceSub unitsKaweka Rakaia amp Pahau Terranes Esk Head Belt Pahaoa amp Clent Hills GroupsUnderliesCaples Terrane Momotu Waka amp Haerenga SupergroupsLithologyPrimaryGreywacke schist basaltLocationRegionCanterbury Marlborough amp Otago RegionsCountryNew ZealandType sectionNamed forTorlesse RangeCross section of New Zealand s stratigraphy Contents 1 Description 2 Deposition 3 Metamorphism 4 Fossil content 5 See also 6 References 7 Further readingDescription EditThe Rakaia Terrane rocks of Permian to late Triassic age 300 200 Ma occur south of Rangiora The Pahau Terrane rocks of Late Jurassic to Early Cretaceous age 160 100 Ma occur to the north and are probably derived from the Rakaia Terrane At the boundary between these two terranes is the Esk Head Belt an 11 kilometre 6 8 mi wide melange of broken and deformed rocks The Aspiring Terrane Aspiring Lithologic Association is officially included within the Torlesse Composite Terrane however it has a higher proportion of igneous rocks and a different sedimentary source 3 Its original relationship with the Rakaia Terrane is obscured by the Haast Schist Deposition EditThe greywacke of the Torlesse Composite Terrane was deposited on the eastern side of New Zealand from the Late Carboniferous through to the Middle Cretaceous It was deposited in giant deep sea fans that extended beyond the ends of ancient submarine canyons A fan starts with a submarine canyon on the continental shelf Then turbidity currents rush down the canyon like giant undersea avalanches They carry all sorts of sediments from the shallower seafloor of the continental shelf At the end of the canyon the turbidity current spreads out and creates giant fans of sediment that blanket the deep seafloor These sediments may have derived in part from the granitic rocks of northeastern Australia as suggested by studies of the mineral grains 4 Metamorphism EditThe Torlesse Composite Terrane has undergone metamorphism and been transformed into Haast Schist In the Haast Schists the minerals that make up greywacke became coarser grained and altered to other minerals including quartz feldspar and biotite 5 Rare pods of pounamu jade are found in the higher metamorphic grades near the Alpine Fault 6 Fossil content EditTorlessia 7 Monotis 8 Hector s Ichthyosaur 9 Nothosaur 10 Conodont 11 See also EditGeology of the Tasman District Stratigraphy of New Zealand Takaka Terrane Dun Mountain Maitai TerraneReferences Edit New Zealand Stratigraphic Lexicon GNS Science New Zealand Geology an illustrated guide PDF www geotrips org nz Jugum D Norris RH Palin JM 2013 Late Jurassic detrital zircons from the Haast Schist and their implications for New Zealand terrane assembly and metamorphism New Zealand Journal of Geology and Geophysics 56 4 223 228 doi 10 1080 00288306 2013 815639 ISSN 0028 8306 S2CID 128551272 Building a continent The Geology of New Zealand Greywacke www gns cri nz GNS Science Cooper Alan F Ireland Trevor R 2015 The Pounamu terrane a new Cretaceous exotic terrane within the Alpine Schist New Zealand tectonically emplaced deformed and metamorphosed during collision of the LIP Hikurangi Plateau with Zealandia Gondwana Research 27 3 1255 1269 Bibcode 2015GondR 27 1255C doi 10 1016 j gr 2013 11 011 ISSN 1342 937X https paperspast natlib govt nz periodicals TRSGEO19650722 2 2 https paperspast natlib govt nz periodicals TRSGEO19650722 2 2 https icebergdb com hectors ichthyosaurtrue organism size parameters 2 https sci waikato ac nz evolution FossilEvidence shtml https teara govt nz en fossils page 2Further reading EditThe Rise and Fall of the Southern Alps G Coates published 2002 Retrieved from https en wikipedia org w index php title Torlesse Composite Terrane amp oldid 1136309162, wikipedia, wiki, book, books, library,

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