The Geology of New Zealand

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The Geology of New Zealand
Gregory S. Springer, PhD Dept. of Geological
Sciences
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New Zealand in Perspective
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Plates
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Distribution of magnitude 5 or greater
earthquakes, 1980 - 1990
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New Zealand On the Edge
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(No Transcript)
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Hotspots and Rifts
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Continental Rifting
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Rifting in Africa
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Wayward New Zealand
140 Ma BP
140 Ma BP
40 Ma BP
today
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New Zealand On the Edge
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New Zealand and the Hikurangi Trough

• PacificAntarctic Plate Boundary

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Faults
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Reverse Fault
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New Zealand On the Edge
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Why does New Zealand even exist?
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New Zealand On the Edge
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Island Arc
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Subduction
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Relationship of earthquake depth to subduction
zones
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Earthquakes Tell Stories!
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New Zealand and the Hikurangi Trough

• Hikurangi Trough

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New Zealand and the Hikurangi Trough

• Chatham Rise Oceanic Plateau

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New Zealand and the Hikurangi Trough

• Hikurangi Oceanic Plateau

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New Zealand and the Hikurangi Trough

• AustraliaPacific Plate Boundary

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New Zealand and the Hikurangi Trough

• Puysegur Subduction - Eastward

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The Nitty Gritty
Here the plate junction is very complex since  
1)  along the alpine fault (South Island) the
plates are sliding past each other.    2) 
North, the Australian plate rides over the
Pacific plate. (Kermadec trench).    3)  South,
the Pacific plate rides over the Australian
plate. (Macquarie ridge).    4)  In the volcanic
triangle of the North Island, the country is
tearing apart, creating the jutting East Cape in
the process.
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New Zealand Strike-Slip Faulting
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South Island and Alpine Fault
Sliding between continental rocks began 25mya
(million years ago)  At the start of sliding, 
New Zealand was barely above sea level and there
were no  mountains. Collision started 10mya
(push-up mountains).
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What controls mountain development?
12 m
lt2 m
What effect does precipitation have?
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Precipitation
12 m
What effect would this have on erosion and
mountain building?
lt2 m
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Asymmetric Erosion
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West-facing wet!
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East dry!
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Till
Glacier Ice
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Glaciers in Action
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Glaciers in Action
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Glacial Flour!
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Glacial Outwash
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New Zealand Streams
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New Zealand Streams
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New Zealand Caves
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Origin of Limestone
Raw ingredient of limestone isCalcium Carbonate
(CaCO3), which forms in seas in a variety of ways.
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Dirt is good!

• Carbonic acid (H2CO3)
• CO2 (g) ? CO2 (aq)
• CO2(ag) H2O
• H2CO3 ? H HCO3-

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New Zealand Caves
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New Zealand Caves
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New Zealand Caves
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New Zealand a little bit of everything.