When did the Andes mountains form?

Date:

Share post:

The Andes have been a mountain chain for much longer than previously thought, new research from the University of Bristol, UK suggests.

When did the Andes mountains form?
The Andean mountains in South America are the second highest mountain 
chain in the world after the Himalayas [Credit: University of Bristol]

The Andes were formed by tectonic activity whereby earth is uplifted as one plate (oceanic crust) subducts under another plate (continental crust). To get such a high mountain chain in a subduction zone setting is unusual which adds to the importance of trying to figure out when and how it happened. However, the timing of when the Andean mountain chain uplift occurred has been a topic of some controversy over the past ten years.

The prevailing view is that the Andes became a mountain range between ten to six million years ago when a huge volume of rock dropped off the base of Earth’s crust in response to over-thickening of the crust in this region. When this large portion of dense material was removed, the remaining portion of the crust underwent rapid uplift.

The timing of such uplift is important in helping scientists to understand how mountains form, how they erode and what impact this may have on global atmospheric circulation patterns and climate.

To investigate the timing of Andean uplift, Dr Laura Evenstar from Bristol’s School of Earth Sciences used a new method based on cosmic rays that create a rare form of helium (cosmogenic He-3) in minerals at Earth’s surface. The abundance of cosmogenic He-3 depends on the altitude of the surface and thus can be used to understand the altitude history of a rock surface.

With collaborators at Scottish Universities Environmental Research Centre and partially funded by BHP Billiton, Dr Evenstar analysed large boulders from 2km high in the western margin of the Andes. She has shown that the Andes were already near their present elevation 14 million years ago.

Dr Evenstar said: “It seems highly likely that the Andes have gone up slowly over at least the last 30 million years, and are the result of gradual thickening of the crust. This means that the uplift of the Andes probable effected large scale atmospheric circulation patterns at least 4 million years before previously thought.”

The research is published in Geophysical Research Letters.

Source: University of Bristol [November 18, 2015]

ADVERTISEMENT

spot_img

Related articles

Nature’s dangerous decline ‘unprecedented,’ species extinction rates ‘accelerating’

Nature is declining globally at rates unprecedented in human history -- and the rate of species extinctions is...

Welcome to the new Meghalayan age – here’s how it fits with the rest of Earth’s geologic history

Jurassic, Pleistocene, Precambrian. The named times in Earth's history might inspire mental images of dinosaurs, trilobites or other...

Acoustic imaging reveals hidden features of megathrust fault off Costa Rica

Geophysicists have obtained detailed three-dimensional images of a dangerous megathrust fault west of Costa Rica where two plates...

Fossilised plant leaf wax provides new tool for understanding ancient climates

New research, published in Scientific Reports, has outlined a new methodology for estimating ancient atmospheric water content based...

Rapid permafrost thaw unrecognized threat to landscape, global warming researcher warns

A "sleeping giant" hidden in permafrost soils in Canada and other northern regions worldwide will have important consequences...

The ups and downs of a mega-lake

Together with an international team, researchers of the Senckenberg Center for Human Evolution and Palaeoenvironment at the University...

Fish of Antarctica threatened by climate change

A Yale-led study of the evolutionary history of Antarctic fish and their "anti-freeze" proteins illustrates how tens of...

What makes soil, soil? Researchers find hidden clues in DNA

Ever wondered what makes a soil, soil? And could soil from the Amazon rainforest really be the same...