Rise of the Himalayas
The evolution of the Himalayas – home to Earth’s highest peaks – is being explained through new research by University of Queensland researcher and geologist Dr Renjie Zhou.
The Himalayas are writ large in human culture, featuring prominently in religion, legend, and tales of adventure and human achievement.
They’re also a geological marvel.
Not many people realise this, but Earth has a third pole – the Himalaya-Tibetan Plateau – with an average elevation of above 4500 metres. Its magnificent topography initiates the monsoonal climate in south Asia, intensifying aridity in central Asia, and serving as a water tower for 1.4 billion people.
It’s also considered a textbook example of a fundamental Earth process – continent-to-continent collision.
Driven by plate tectonics, the Indian subcontinent broke off from the Australian continent around 200 million years ago. It then travelled to the north across the ancient Tethys Ocean and collided with the southern margin of Eurasia only some tens of million years ago.
The collision is still ongoing, with the Indian subcontinent traveling at several centimetres per year (a very fast speed in geological terms), causing continuous mountain uplift and natural hazards such as earthquakes and landslides.
Knowing how, when, and why geological events took place in the course of the Indian subcontinent’s journey to the north has become a never-ending task for numerous Earth scientists around the globe.
New data from India
Everything you need to know about the Himalaya has been written in the rock record.
Members from the tectonics research team at UQ’s School of Earth and Environmental Sciences have worked along the India-Eurasia collision zone, from northwest India, southern Tibet, and to the bounder between Myanmar and India. The team was absolutely obsessed with deciphering the rich and interesting stories from all kinds of rocks and fossils.
Some insightful new work looking at the rise of the Ladakh Range – a key member in the western Himalayas – was recently published in the Journal of The Geological Society. In this study, we took a careful look at the sediment accumulated at the foothill of the Ladakh Range and analysed it with some of the newest instruments at the UQ Centre for Geo-analytical Mass Spectrometry (CGMS).
Our idea was to trace the source of this sediment, hoping that this would inform us about the topographic conditions in the past, as the source of the sediment would intuitively be higher than site of accumulation. We discovered that all of the sediment that was sourced was from the nearby Ladakh Range.
This was a big surprise, as there was no direct evidence for surface uplift there and geologists had hypothesised a much older rise for this range, older than 23-24 million years ago as concluded in our work. This really would push us to re-think how this growth happened in the Ladakh Range and re-evaluate other changes in the landscape.
And aside from the rewarding science, working in the northwest Himalayas gave us great joy interacting with local people. Our field guides all became well-versed geologists by the end of the field seasons. Look at the geologically-inspired celebration cake they made! Gabbros, ophiolites, eclogites… these are all geological terms. The perfect treat to celebrate all of the exciting rocks in the Himalayas.
Understanding the Australian continent
Studying and learning plate tectonic processes will equip us in understanding some of the fundamentals of geoscience. If we can understand the Australian continent, we’ll have a better grasp of the resources under our soils, which can help us build a low-carbon, renewable-energy future.
The Australian continent is as old as several billion years, assembled through various plate tectonics processes. Many geological events in Australia have a more geologically modern example, which can be better exposed and preserved. For example, the vast area of the eastern Australia used to be a mountain system – much like the present-day Andes – just a few hundreds of millions years ago. Evidence also exists for continual collision and gradual continental growth across the country.
It’s an exciting time in geological science. UQ is able to have a critical part in exploring the creation – and the future – of our world.
· Unroofing the Ladakh Batholith: constraints from autochthonous molasse of the Indus Basin, NW Himalaya - Journal of the Geological Society (2020).