[ad_1]
This graph shows how the former landmasses of Laurentia, Avalonia and Armorica would have come together to create the countries of England, Scotland and Wales. Credit: Plymouth University
According to new research, the British mainland was formed by the collision of two, but not ancient, landmasses.
For centuries, scientists believed that England, Wales and Scotland had been created by the merger of Avalonia and Laurentia, there are more than 400 million of them. ; years.
However, geologists based at Plymouth University now believe that a third land mass – Armorica – has also been involved in the process.
The results are published in Nature Communications and follow a thorough study of the mineral properties of exposed rocks across Devon and Cornwall.
They reveal a clear border crossing the two counties, with northern regions sharing their geological roots with the rest of England and Wales, but all that is to the south being geologically linked to France and Europe mainland.
Scientists believe that research explains the abundance of tin and tungsten in the extreme south-west of England – metals that are also found in Britain and other parts of Europe. continental, but not in the rest of the United Kingdom.
Dr. Arjan Dijkstra, senior research author and lecturer in igneous petrology, said, "This is a completely new way of thinking about the formation of Britain." It has always been assumed that the border between Avalonia and Armorica the natural limit of the Channel, but our results suggest that, although there is no physical line on the surface, there is a clear geological boundary separating Cornwall and southern Devon from the rest of the United Kingdom. United. "
For research, Dr. Dijkstra and Master's student Callum Hatch (currently working at the Museum of Natural History) visited 22 sites in Devon and Cornwall that were exposed following geological events such as eruptions volcanic underground. These took place about 300 million years ago and brought the magma 100 km deep to the surface of the Earth.
They took rock samples from each site and subjected them to detailed chemical analysis in the laboratory using X-ray fluorescence spectrometry (FRX).
The samples were then dissolved in acid in order to conduct a more intensive isotope analysis, with scientists examining the two element levels, strontium and neodymium, to understand the entire history of the rocks.
Dr. Arjan Dijkstra subjected samples to detailed chemical analyzes using X-ray fluorescence spectrometry (FRX) and, dissolving them in acids, he proceeded to a more intensive isotopic analysis. Credit: Plymouth University
These results were then compared to previous studies conducted elsewhere in the UK and continental Europe, with results showing clear boundaries ranging from the Exe estuary to the east to Camelford in the west.
"We have always known that about 10,000 years ago, you could have walked from England to France," added Dr. Dijkstra. "But our results show that millions of years ago the links between the two countries would have been even stronger, which explains the immense mineral wealth of south-west England, which was previously a mystery, and fascinating new lighting in the geological history of the United Kingdom. "
Explore more:
Who do you really think? The first fine-scale genetic map of the British Isles
More information:
Arjan H. Dijkstra et al, Mapping of a hidden terrane boundary in mantle lithosphere with lamprophyres, Nature Communications (2018). DOI: 10.1038 / s41467-018-06253-7
Source link
