He Himalayas It is the highest mountain range on earth With a height of around 8,850 m, it stretches over as many as six countries: Nepal, Bhutan, China, India, Burma and Pakistan and contains the two highest peaks in the world: the famous one Everest and the k2.
A new study by a research team is now available Doerr School of Sustainability at Stanford University (USA) and published in the journal Nature Geoscience has enabled us to find one new technique for surveying the topography of the past.
With that it is shownThe Himalayas were already more than halfway to their peak before a continental collision made them the world’s tallest mountain range. Mountain ranges play a key role in global climate, altering the weather and shaping the flora and fauna that live on their slopes and valleys below.
As warm air rises upwind and cools, moisture condenses into rain and snow. On the leeward side, however, the opposite is the case: deserts prevail, a phenomenon known as rain shadows.
So this team of researchers has now adapted a technique for studying meteorites to measure historical heights in sedimentary rocks and show that the Himalayas did not form in the way experts had long assumed: “The main controversy lies in what existed before the Himalayas .” existed,” explains the first author of the study, Page Chamberlain, Professor of Earth and Planetary Sciences and Earth Systems Science at the Doerr School of Sustainability.
This study shows “for the first time that the edges of the two tectonic plates were already quite high before the collision that led to the Himalayas: an average of about 3.5 kilometers. That’s more than 60% of their current height,” he adds. Daniel Ibarra, new postdoctoral fellow in Chamberlain’s lab.
That is, “much higher than many thought, and this new understanding could reshape previous climate and biodiversity theories.” At the very least, the results are forcing a recalibration of old climate models and will likely lead to new paleoclimate hypotheses about the Himalayan region of southern Tibet, an area , which is known as the Arch of the Ganges.
Other mountain ranges such as Andes and Sierra Nevada
It could also lead to a more detailed study of other important mountain ranges like the Andes and Sierra NevadaTo. The reason this centuries-old debate has suddenly flared up has a lot to do with the challenges posed by measuring past topographic heights, an area known as paleoaltimetry.
This is extremely difficult work, the researchers say, because there aren’t many surrogate indicators of elevation in the geological record, but the Stanford team, working with study authors from the China University of Geosciences, found one.
Not only are the rains heavier on the windward slopes, but the chemical composition of the precipitation changes as the air rises toward the peaks. The heavier isotopes tend to fall out first; easiest near the summit.
So, by analyzing the isotopic composition of the rocks, experts can find clues about the elevation at which they were deposited. In the sediment record, oxygen occurs in three stable isotopes: oxygen 16, 17, 18. The key isotope, oxygen 17, is extremely rare. It makes up just 0.04% of the oxygen on earth. This means that in a sample with a million oxygen atoms, there are only four oxygen atoms 17.
“There are maybe eight labs in the world that can do this analysis,” says Chamberlain, who helped process the samples at Stanford’s Earth Paleoclimate Lab. Still, it took us three years to get numbers that made sense and worked every day. days”. This explains why triple oxygen analysis as an indicator of ancient altitude has been overlooked, or perhaps too easily dismissed.
Page Chamberlain and his colleagues used a grant from the Heising-Simons Foundation to adapt the technique for paleoaltimetry and used the Sun Valley Mountains for a 2020 proof-of-concept paper and focused once the scientific basis was established was, back to the Himalayas.
By sampling quartz veins from lower elevations in southern Tibet and using triple oxygen analysis, the team showed that lThe foundations of the Gangdesic Arc were already much higher than expectedlong before a tectonic collision occurred.
“Experts have long held that it takes a massive continent-continent-scale tectonic collision to produce the kind of uplift needed for Himalayan-scale uplifts,” says Ibarra. “This study refutes that.” and opens up new insights.” and interesting horizons”.
