The buried secrets of earth’s past
Scientists investigating rocks in Oman have found new windows into the creation of mountains and continents.
Dr Ian Alsop, of the University of St Andrews, has just returned from a trip to the mountains of Oman where he investigated ancient rock folds up to 70 million years old. Such folds give insights into how the plates that make up the Earth’s crust form and move.
Along with colleagues from Oxford University, Dr Alsop found examples of rock folds which were larger and more clearly exposed than any found before, allowing for greater insights to be gained.
“As rocks deep underground are pressed and heated, they melt and begin to flow. This forms folds, like a rucked-up carpet”, explained Dr Alsop, an international expert on folds.
The folds in Oman show that the rocks moved many tens of kilometres while deep within the Earth. They also show what Dr Alsop calls “huge amounts of shearing,¿ which refers to the stresses that deform the rock.
“The folds that we have been analysing in Oman formed about 70 million years ago and are unique in that they display some of the largest, best exposed curved geometries exposed anywhere on Earth,” says Dr Alsop, who works in the School of Geography and Geosciences at St Andrews.
Oman has rugged mountains split by steep wadis, or dry riverbeds, which expose many of these folds in great detail. Such folds may be pushed as deep as 100 kilometres underground before returning to the Earth’s surface in a dramatic mountain range like this one. Also visible now are portions of crust which were once under the ocean.
Dr Alsop and his colleagues will return to Oman for more fieldwork later in the year, as part of an ongoing project funded by the Royal Society.
He said, “It is likely that similar formations occur in mountain ranges elsewhere in the world but are less well exposed and more difficult to identify than in Oman.”
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Ref: Oman rocks 120207.doc
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