Geology of New Zealand
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The geology of New Zealand is noted for its
New Zealand's
Basement rocks (Cambrian-Cretaceous)
New Zealand's
The Western Province is older than the Eastern Province and outcrops along the west coast of the South Island from
Large sections of the Western Province have been intruded by
The Eastern Province underlies more of New Zealand than the Western Province, including the greywacke and schist of the Southern Alps and all of the basement rocks of the North Island. The Eastern Province contains seven main terranes, the
Many rocks in the Eastern Province have been metamorphosed into the
Separation from Gondwana (Cretaceous-Eocene)
The Australia-New Zealand continental fragment of Gondwana split from the rest of Gondwana in the late Cretaceous time (95–90 Ma). Then around 83 Ma, Zealandia started to separate from Australia forming the
Currently, New Zealand has no native snakes or land mammals (other than bats). Neither
The landmasses continued to separate until early
Sedimentary basins and allochthons (Cretaceous–Recent)
An
Volcanic activity
Volcanism is recorded in New Zealand throughout its whole geological history. Most volcanism in New Zealand, both modern and ancient, has been caused by the subduction of one tectonic plate under another; this causes melting in the
Extinct volcanoes
The South Island has no currently active volcanoes. However, in the late Cretaceous (100–65 Ma), there was widespread volcanic activity in Marlborough, West Coast, Canterbury and Otago which contributes to landforms such as Mount Somers. In Eocene times (40 Ma), there was volcanic field activity near present day Oamaru. The most well known Miocene volcanic centres are the intra-plate Dunedin Volcano and Banks Peninsulas. The Dunedin Volcano which later eroded to form Otago Peninsula near Dunedin was built up by a series of mainly basaltic intra-plate volcanic eruptions in Miocene times (16–10 Ma).[15] Banks Peninsula near Christchurch was built from two mainly basaltic intra-plate volcanoes in Miocene times (12–6 Ma and 9.5–7.5 Ma), corresponding to the Lyttelton / Whakaraupo and Akaroa Harbours. Southland's Solander Islands / Hautere were active as recently as 150,000 years old.[16] There are also minor volcanics from a similar time period throughout Canterbury, Otago and also on the Chatham Islands.
Intra-plate basaltic volcanic eruptions also occurred in the North Island, near the Bay of Islands in Northland, in the Late Miocene (10 Ma), and again more recently (0.5 Ma). The South Auckland volcanic field was active in Pleistocene times (1.5–0.5 Ma). The Auckland volcanic field started erupting around 250,000 years ago. It includes around 50 distinct eruptions, with most of the prominent cones formed in the last 30,000 years, and the most recent eruption, which formed Rangitoto Island, around 600 years ago. The field is currently dormant and further eruptions are expected. Over time the volcanic field has slowly been drifting northwards.[17]
Volcanism in the North Island has been dominated by a series of volcanic arcs which have evolved into the still active
Shortly after (18 Ma), a volcanic arc developed further east to create the
Active volcanoes and geothermal areas
After this, activity shifted further East to the Taupō Volcanic Zone, which runs from the
The Tongariro Volcanic Centre developed over the last 275,000 years and contains the active andesitic volcanic cones of Ruapehu, Tongariro, and
The
A line of undersea volcanoes extends out along the
The Taupō Volcanic Zone is known for its
Modern tectonic setting and earthquakes
New Zealand is currently astride the convergent boundary between the Pacific and Australian Plates. Over time, the relative motion of the plates has altered and the current configuration is geologically recent. Currently the Pacific Plate is subducted beneath the Australian Plate from around
The Pacific Plate is colliding with the Australian Plate at a rate of about 40 mm/yr.
Great stress is built up in the Earth's crust due to the constant movement of the tectonic plates. This stress is released by earthquakes, which can occur on the plate boundary or on any of thousands of smaller faults throughout New Zealand. Because the Pacific Plate is subducting under the eastern side of the North Island, there are frequent deep earthquakes east of a line from the Bay of Plenty to Nelson (the approximate edge of the subducted plate), with the earthquakes being deeper to the west, and shallower to the east. Because the Australian Plate is subducting under the Pacific Plate in Fiordland, there are frequent deep earthquakes near Fiordland, with the earthquakes being deeper to the east and shallower near the west.
Shallow earthquakes are more widespread, occurring almost everywhere throughout New Zealand (especially the Bay of Plenty,
Paleoclimate of New Zealand
Since Zealandia separated from Gondwana (80 mya) in the Cretaceous the climate has typically been far warmer than today. However, since the Quaternary glaciation (2.9 mya) Zealandia has experienced climate either cooler or only slightly warmer than today.
In the Cretaceous, New Zealand was positioned at 80 degrees south at the boundary between Antarctica and Australia. But it was covered in trees as the climate of 90 million years ago was much warmer and wetter than today.
Over the past 30,000 years three major climate events are recorded in New Zealand, the
Geological hazards
New Zealand suffers from many natural hazards, including
The largest earthquake in New Zealand was an M8.2 event in the
New Zealand is at risk from tsunamis that are generated from both local and international faults. The eastern coast of New Zealand is most at risk as the Pacific Ocean is more tectonically active than the Tasman Sea. Locally the faults along the North Island's east coast provide the greatest risk. Minor tsunamis have occurred in New Zealand from earthquakes in Chile, Alaska and Japan.
There are many potentially dangerous volcanoes in the Taupō Volcanic Zone. The most severe volcanic eruption since the arrival of Europeans is the Tarawera eruption in 1886. A lahar from Mount Ruapehu destroyed a bridge and derailed a train in December 1953, killing 151 people. Even a minor eruption at Ruapehu could cause the loss of electricity for Auckland, due to ash on the power lines, and in the Waikato River (stopping the generation of hydroelectric power).
Many parts of New Zealand are susceptible to landslides, particularly due to deforestation and the high earthquake risk. Much of the North Island is steep, and composed of soft mudstone known as papa,[36] that easily generates landslides.[37]
Geological resources
New Zealand main geological resources are coal, gold, oil, and natural gas.
History of New Zealand geology
The detailed study of New Zealand's geology began with
The Geological Survey of New Zealand now known as GNS Science has done extensive mapping through New Zealand at 1:250,000 and 1:50:000 scales. The most modern map series are the "QMAPs" at 1:250,000.[47] New Zealand's geological research is published by GNS Science, in the New Zealand Journal of Geology and Geophysics, and internationally. A Map showing the distribution of earthquakes in New Zealand can be obtained from Te Ara: The Encyclopedia of New Zealand.[48] Current earthquake and volcanic activity can be obtained from the GeoNet website.[49] The universities of Auckland, Canterbury, Massey, Otago, Victoria and Waikato are activity engaged in geological research in New Zealand, Antarctica, the wider South Pacific and elsewhere.
See also
- Alpine Fault
- Geography of New Zealand
- Hikurangi Trench
- Indo-Australian Plate
- Kaikōura Canyon
- List of dinosaurs of New Zealand
- List of earthquakes in New Zealand
- List of rock formations in New Zealand
- Marlborough Fault System
- Natural history of New Zealand
- New Zealand geologic time scale
- North Island Fault System
- Pacific Plate
- Stratigraphy of New Zealand
- Zealandia (continent)
Regional geology
- Geology of the Northland Region
- Geology of the Auckland Region
- Geology of the Waikato-King Country Region
- Taupō Volcanic Zone
- Geology of the Raukumara Region
- Geology of Taranaki
- Geology of the Wellington Region
- Geology of the Tasman District
- Geology of Canterbury, New Zealand
- Geology of the West Coast Region
References
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- ^ New Zealand within Gondwana from Te Ara: The Encyclopedia of New Zealand
- ^ "New Zealand Geology: an illustrated guide" (PDF). www.geotrips.org.nz.
- .
- ISSN 1342-937X.
- ^ "New Zealand Stratigraphic Lexicon". GNS Science.
- .
- ^ "Dinosaur footprints found in Nelson on show in Lower Hutt". www.stuff.co.nz. 6 September 2016.
- ISSN 0028-8306.
- ISSN 0016-6995.
- S2CID 25885140.
- ^ New Zealand splits from Gondwana from Te Ara: The Encyclopedia of New Zealand
- PMID 17957581.
- S2CID 129198310.
- ^ ""Eruptions and deposition of volcaniclastic rocks in the Dunedin Volcanic Complex, Otago Peninsula, New Zealand", Ulrike Martin". Archived from the original on 8 June 2011. Retrieved 8 November 2018.
- ISSN 0377-0273.
- ISSN 0016-7606.
- ISSN 0303-6758.
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- ^ "Taupo – Eruptive History". Global Volcanism Program. Smithsonian Institution. Archived from the original on 17 November 2011. Retrieved 16 March 2008.
- S2CID 134907436.
- ^ Bunn and Nolden, Rex and Sascha (December 2016). "Te Tarata and Te Otukapuarangi: Reverse engineering Hochstetter's Lake Rotomahana Survey to map the Pink and White Terrace locations". Journal of New Zealand Studies. NS23: 37–53.
- ^ Hall, Matthew (2004). Existing and Potential Geothermal Resource for Electricity Generation. Ministry for Economic Development.
- ^ Diagram showing the Australian-Pacific Plate Boundary
- ISSN 0956-540X.
- ISSN 0016-7606.
- ^ New Zealand uplift and sinking from Te Ara: The Encyclopedia of New Zealand
- ISSN 0028-825X.
- PMID 17159151.
- ^ S2CID 130794280.
- ^ "NZ paleoclimate poster". www.gns.cri.nz. GNS Science.
- ISSN 0277-3791.
- ^ New Zealand during the last glacial maximum from Te Ara: The Encyclopedia of New Zealand
- ^ David Wratt; Jim Salinger; Rob Bell; Drew Lorrey & Brett Mullan (28 February 2007). "Past climate variations over New Zealand". NIWA. Retrieved 5 June 2014.
- ^ Science, GNS. "Where were NZs largest earthquakes? / New Zealand Earthquakes / Earthquakes / Science Topics / Learning / Home – GNS Science". www.gns.cri.nz. Retrieved 27 November 2018.
- ^ Nathan, Simon (2 March 2009). "Rock and mineral names – Local names". Te Ara – the Encyclopedia of New Zealand. Retrieved 28 December 2011.
- ^ Nathan, Simon (24 September 2011). "Rock and mineral names". Te Ara – the Encyclopedia of New Zealand. Retrieved 28 December 2011.
- ^ "Coal Overview". Crown Minerals, Ministry of Economic Development. 17 December 2008.
- ^ "NZ Gold History Archived 5 February 2014 at archive.today," New Zealand Gold Merchants Ltd., retrieved 5 February 2014.
- ^ "Petroleum Overview". Crown Minerals, Ministry of Economic Development. 26 June 2008.
- ^ "Huge ironsands expansion – Quarrying & Mining Magazine". Quarrying & Mining Magazine. 11 November 2014. Retrieved 1 February 2018.
- ISSN 0375-6505.
- ^ Johnston, M. R.; Nineteenth-century observations of the Dun Mountain Ophiolite Belt, Nelson, New Zealand and trans-Tasman correlations, Geological Society, London, Special Publications 2007, v. 287, p. 375-387
- ISBN 9780477010573.
- ISBN 9781862392557.
- ISBN 9780267981571.
- ^ GNS Science
- ^ Map showing the distribution of earthquakes in New Zealand from Te Ara: The Encyclopedia of New Zealand.
- ^ Geonet Archived 8 January 2008 at the Wayback Machine – Current New Zealand Earthquake and Volcanic Activity.
Further reading
- Graham, Ian J. et al.;A continent on the move : New Zealand geoscience into the 21st century – The Geological Society of New Zealand in association with GNS Science, 2008. ISBN 978-1-877480-00-3
- Campbell, Hamish; Hutching, Gerard; In Search of Ancient New Zealand, Penguin Books in association with GNS Science, 2007, ISBN 978-0-14-302088-2
- Te Ara: The Encyclopedia of New Zealand An Overview of New Zealand Geology
- Hot Stuff to Cold Stone – Aitken, Jefley; GNS Science, 1997. ISBN 0-478-09602-X.
- Rocked and Ruptured – Aitken, Jefley; Reed Books, in association with GNS Science, 1999. ISBN 0-7900-0720-7.
- The Rise and Fall of the Southern Alps – Coates, Glenn; Canterbury University Press, 2002. ISBN 0-908812-93-0.
- Plate Tectonics for Curious Kiwis – Aitken, Jefley; GNS Science, 1996. ISBN 0-478-09555-4.
- Lava and Strata: A guide to the volcanoes and rock formations of Auckland – Homer, Lloyd; Moore, Phil & Kermode, Les; Landscape Publications and the Institute of Geological and Nuclear Sciences, 2000. ISBN 0-908800-02-9.
- Vanishing volcanoes : a guide to the landforms and rock formations of Coromandel Peninsula – Homer, Lloyd; Moore, Phil; Landscape Publications and the Institute of Geological and Nuclear Sciences, 1992. ISBN 0-908800-01-0.
- Reading the rocks : a guide to geological features of the Wairarapa Coast – Homer, Lloyd; Moore, Phil & Kermode, Les; Landscape Publications and the Institute of Geological and Nuclear Sciences, 1989. ISBN 0-908800-00-2
External links
- Paleographic Maps of New Zealand from late Cretaceous time from GNS Science
- Geological Society of New Zealand
- New Zealand Journal of Geology and Geophysics Archived 10 May 2009 at the Wayback Machine
- A simple geological map of New Zealand from Te Ara: The Encyclopedia of New Zealand