The study provides new insights into the formation of the Himalayas and challenges existing theories
Representative image
(Piyal Bhattacharjee/TOI, Delhi, BCCL)
Picture a calm ocean, some silent ripples, and a cinematic slow-motion collision between two giant pieces of land. Later, the sea disappeared, and a mountain range rose in its place from the impact of this massive collision.
This is the origin story of one of the highest and youngest mountain ranges in the world: the Himalayas – or so we are told. But now, recently published research by geologists from Stanford University challenges the origin story of the Himalayas.
A new twist on the traditional tale
In this study, the researchers adopted paleometry — a technique used to study meteorites to measure historical elevations in sedimentary rocks — and were shocked to discover that the great mountain range had not exploded in a unique catastrophic event.
While the continent-to-continent collision of the Indian Plate and the Eurasian Plate did occur, it was just a final push and had little to do with the initial uplift.
Instead, they found that tectonic plates were actually pressing against each other, effectively causing the Himalayas to rise to approximately 3.5 kilometers or 3,500 meters on average, nearly 60% of their current height! Nowadays, the average elevation of the Himalayas is 6,100 metres, and includes the world’s tallest mountain, Mount Everest, which is 8,849 meters above sea level.
The study suggests that while the tectonic dance began 63 to 61 million years ago due to subduction of the oceanic portion of the Indian tectonic plate, continent-to-continent collision eventually created the towering peaks about 45 to 59 million years ago. .
But how have we not put this together before? Well, the researchers explain that measuring past topographic elevations is quite a challenge. For example, we have ice cores that represent past climate – temperature, precipitation and even solar activity. But there are not many clues to what the elevation might be in the geological record.
Opening the Himalayan Oxygen Archives
Searching for a reliable proxy for elevation, the researchers collaborated with study authors from the China University of Geosciences (Beijing), and finally found one – and it had something to do with rainfall on mountain slopes! Based on how the chemical composition of rainwater changed as the storm’s winds peaked, they looked for different oxygen isotopes among the ancient sedimentary rocks.
As you can see, the heavier isotopes tend to fall first, while the lighter isotopes fall near the peaks. So, with the isotopic composition in hand, they can assess at what height raindrops fell and at what point in the past.
Oxygen analysis revealed that the composition about 62 million years ago was consistent with an elevation of 11,480 feet, or 3,500 metres.
Then, in a massive collision 45 to 59 million years ago, the edges of the Indian and Eurasian plates finally broke apart, helping the mountain rise an additional 1,000 metres. Interestingly, these tectonic forces are still ongoing, contributing to the growth of the Himalayas even today!
These discoveries have pushed geologists in a completely new direction, as they could be the missing link that further demystifies climate phenomena such as the monsoon system in East and South Asia. Furthermore, the findings also spark closer scrutiny into the origin of other mountain ranges, reshaping our understanding of past climates and biodiversity.
The study was recently published in the journal Natural earth sciences It can be accessed here.
**
For weather, science, space and COVID-19 updates on the go, download Weather channel app (On Android and iOS store). It’s free!
