Taxonomy term

tectonics

In feats of tectonic strength, grain size matters

Plate tectonics involves some of the most powerful forces on Earth, but the lithosphere, of which the plates are made, is not infinitely strong: Weaknesses in the lithosphere allow it to break apart and form plate boundaries. Determining the strength of tectonic plates based on field observations has proved tricky, however, due to the sheer scale of plates, while experiments and calculations in the lab on olivine — the main mineral that makes up the lithosphere — have depicted plates as misleadingly strong. In a new lab-based study, researchers have taken a novel approach to testing olivine’s strength, and the results fit existing models of plate tectonics better than previous efforts.

04 Jan 2018

Tectonic rejuvenation in North America's ancient mountains

The mountains of eastern North America, like the Appalachians, Adirondacks and White Mountains, are old: They grew as the pieces of the supercontinent Pangea collided and assembled more than 300 million years ago. It’s been long thought that, after forming — and subsequently undergoing additional uplift and deformation due to rifting during the opening of the Atlantic Ocean — the mountains fell dormant between about 160 million and 200 million years ago. But new work is adding to a growing body of evidence suggesting the ranges were tectonically active well after that.

29 Sep 2016

Going with the flow: Mapping the mantle under the Cascadia Subduction Zone

The Cascadia Subduction Zone (CSZ), off the Pacific Northwest coast of the United States and Canada, is one of the world’s most mysterious — and potentially dangerous — earthquake zones. Eerily quiet since a massive magnitude-9 event in 1700, scientists have long warned that the 1,000-kilometer-long fault zone could produce another devastating earthquake and tsunami. Now, a new effort to map the fault zone’s tectonic environment, including the underlying mantle, is shedding light on some of the dynamic forces that may influence earthquakes in the region.

25 Mar 2016

The ups and downs of an island

In 1835, Captain Robert FitzRoy and the crew of the HMS Beagle — who were exploring and studying the Chilean coast with Charles Darwin in tow — arrived at Isla Santa Mariá near the city of Concepción six weeks after a magnitude-8.5 earthquake jolted the region. Along with scenes of dried seaweed and dead mussels lining the island’s shores well above the high-tide line, comparison of a bathymetric survey of a shallow bay adjacent to Santa Mariá to one conducted the previous year suggested to FitzRoy that the earthquake had thrust the island 2.4 to 3 meters out of the water.

18 Mar 2016

Himalayas get a new birthdate

The Himalayas are the highest and widest mountain range on the planet, but when they began forming has never been clear. In a new study, researchers have now pinpointed the date of the initial collision between India and Eurasia that led to the birth of the Himalayas.

05 Mar 2016

Stalled slabs sometimes stopped by mineral strengthening

Subduction of tectonic plates into the mantle functions as an eons-long recycling system for Earth’s crust and lithosphere. But in some subduction zones, the downgoing slabs seem to get stuck at depths of about 1,000 kilometers, held up by some unseen barrier on their journey deeper into the lower mantle. Now, scientists propose that this barrier might be related to high-pressure-induced strengthening of minerals in the rocks surrounding subducting slabs at these depths.
09 Aug 2015

Rainwater penetrates into ductile crust

Rainwater is capable of percolating deeper into Earth’s crust than once thought possible, according to a new study. The finding could impact our understanding of mountain building, the behavior of rock deep underground and the formation of hydrothermal mineral deposits.

27 Dec 2014