NEW Zealands Zealandia

 
*  Geologists claim to have discovered a new continent to the east of Australia
 
"Geologists claim to have discovered a new continent to the east of Australia: Zealandia. At 4.9 million square kilometres of land mass, 94 per cent of which is under water, Zealandia would be the world's smallest continent. 
 
The 11 scientists behind the claim presented their findings in the study "Zealandia: Earth's Hidden Continent" in Geological Society of America, making a case for Zealandia to be recognised as the world's eighth continent in its own right.
 
According to their study, the land mass comprises all the four attributes needed to be considered a continent, including the presence of different rock types and crucially "the high elevation relative to regions floored by oceanic crust."

"It was not a sudden discovery but a gradual realisation," the scientists wrote.  
 

* Zealandia
 
The term Zealandia was coined by geophysicist Bruce Luyendyk in 1995, at which time it was believed to possess three of the four necessary qualities required for continent status. A recent discovery using satellite technology and gravity maps of the sea floor have revealed that Zealandia is a large unified area, fulfilling all four requirements. [....]

According to the study, the 94 per cent of Zealandia currently submerged broke away from Australia and sank 60-85 million years ago."
 
Original Article found here.
 
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 An elevation map of Zealandia and nearby Australia
Picture Credit: GSA Today
 
 
* New Zealand’s Tectonic Dragon Awakens

"New Zealand is a country in which sheep outnumber people by a factor of six, and its serene pastures have a timelessness that feels exempt from change. But November 14th 2016's magnitude-7.8 earthquake, centered near Kaikoura, sixty miles north of Christchurch, was a brutal reminder that, beneath its verdant carpet, New Zealand is still under active construction. 
 
It occupies one of the most complex geologic venues on the globe, at the messy boundary of two tectonic plates. The North Island, where the capital, Wellington, lies, is part of the Australian plate, and its landscape is dominated by two dozen active volcanoes. (One of these, the Taupo caldera, is notorious in the annals of volcanology as the site of Earth’s most recent super-eruption, twenty-six thousand years ago, which covered parts of the island in ejecta six hundred feet deep. Outside geophysical circles, the region is more generally famous as the home of Mt. Doom in the "Lord of the Rings” films.)
 
The plate boundary lies about forty miles offshore, at the Hikurangi trench, a deep warp in the ocean floor where the Pacific crust slides westward beneath the Australian plate. Meanwhile, off the southern end of the South Island, the configuration is reversed—that is, the Australian plate sinks eastward beneath the Pacific plate. In between these two mirror-image subduction zones lies the South Island, which acts as a tectonic intermediary, accommodating the differential motion via a complex system of faults, like a team of diplomats doing their best to avert a head-on collision between superpowers.
 
The main mediating structure in the South Island is the Alpine Fault, a boundary in some ways analogous to California’s San Andreas Fault. As on the San Andreas, the sense of slip on the Alpine is right lateral—like the motion of cars, as viewed from above, on a two-lane road in New Zealand, which retains the British practice of driving on the left. The Alpine displaces rocks on either side horizontally by about an inch and a half per year, which amounts to roughly a hundred feet of offset since the Maori arrived, in the thirteenth century, or more than three hundred miles over the life of the fault.
 
Given the Alpine Fault’s setting, in the vise between two converging plates, it must also absorb a large amount of tectonic squeezing. This forces rocks in the Pacific plate upward at a rate of almost half an inch per year, and over time this has formed the spine of the South Island, the Southern Alps. (They would be the fastest-rising mountain belt in the world if only the rain on their western slopes weren’t so efficient at eroding them away again.)
 
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 Awaroa beach adjoining the Abel Tasman National Park at the top of New Zealand's South Island
Picture Credit: AFP/Getty Images 
 
 
The South Island in fact owes its very existence to the Alpine Fault, which raises submerged rocks above sea level. One of New Zealand’s geologic peculiarities is that its continental shelf—the relatively shallow seabed surrounding it—is about eighteen times larger than its land area. This portion of the crust was once attached to Australia (a fact that many Kiwis may be reluctant to acknowledge) but rifted away in Cretaceous time to form a separate block. Some geologists even argue that it ought to be considered an eighth continent, Zealandia. As long as the current plate configuration and rates of uplift persist (and continue to outstrip sea-level rise), more of Zealandia will emerge from the ocean in the future.

If the South Island as a whole bears the brunt of the complex relationship between the Australian and Pacific plates, its northern end, where this week’s earthquake occurred, is the very pivot point where the subduction zone transitions into the Alpine Fault. Tremors are therefore common in this region, but the November 14th event was the largest since 1929 and the first of this magnitude to be monitored with modern geophysical instruments. 
 
A preliminary interpretation of the seismic records suggests that the earthquake, like the one that devastated Christchurch in 2010, was a composite event—in other words, it involved slip on more than one fault. One line of evidence for this is the unusually long duration of the slip (about two minutes) and the fact that the main energy release happened not at the onset, as is typical in single-fault failures, but more than forty seconds later. The spatial pattern of the first-arriving seismic waves also points to an untidy, multiple-fault mechanism.
 
A major concern now is how the earthquake may be related to stresses on the subduction zone itself, and whether this event portends something disastrous along the Hikurangi trench, which has been unusually quiet compared with other subduction zones around the Pacific rim. Remarkably, this powerful tremor appears to have caused only two deaths, in part because it occurred in a rural area in the middle of the night. Outside urban areas, its primary effect was to trigger large landslides that blocked transportation arteries, including the main highway and rail line along the northeast coast of the South Island. This lends credence to the emerging paradigm that sublime landscapes like New Zealand’s are shaped not by the gradual processes traditionally invoked by geologists but by violent, episodic upheavals that shake the seemingly tranquil hills occupied by sheep and humans alike."

Marcia Bjornerud is a professor of geology at Lawrence University, in Appleton, Wisconsin, and the author of "Reading the Rocks: The Autobiography of the Earth.” Original article found here.
 
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Zealandia is shown in grey to the east of Australia
Picture Credit: GSA Today
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