We all know Mordor, the volcano-peppered wasteland where Sauron dwells in the Lord of the Rings trilogy, is a fantasy land, right? … Right? Don’t be so sure. As fortune would have it, geologists have discovered a landscape that bears an uncanny resemblance to Mordor — under the ocean.
Using advanced imaging techniques, geologists at the University of Aberdeen in the UK and the University of Adelaide and the Australian Resources Research Centre, both in Australia, in Australia captured the very first 3D images of 26 different volcanic sites in the Bight Basin Igneous Complex off the southern coast of Australia. What they found, buried deep below the seafloor sediment, was an array of craggy, sharp, jagged volcanos ranging from about 200 to 2,050 feet in height — about half the height of Mordor’s Mount Doom, according to The Atlas of Middle-Earth. This wicked-looking landscape includes 26 lava flows as wide as nine miles and as long as 21 miles.
“By using data acquired as part of oil exploration efforts, we have been able to map these ancient lava flows in unprecedented detail, revealing a spectacular volcanic landscape that brings to mind illustrations from Lord of the Rings,” said University of Aberdeen geology lecturer Nick Schofield, Ph.D., one of the study’s co-authors, in a statement earlier in January.
The team published their findings in a paper in the American Geophysical Union journal Geochemistry, Geophysics, Geosystems on November 10, 2017. The study’s authors couldn’t simply glimpse these volcanoes since they were covered in many feet of seafloor sediment. Or, to put it another way:
Advanced imaging was required. In the paper, the researchers describe how this 35 million-year-old landscape may have formed, especially as a result of magmatic intrusions controlling the flow of this undersea magma. The team’s research gives us an unprecedented look at submarine volcanoes, which, despite being incredibly abundant, are very hard to observe. By using seismic reflection to render 3D images of these volcanic regions, the researchers have introduced a powerful new tool to further the study of underwater volcanic activity.
“By using this technique, we have a unique insight into a landscape that has remained hidden for millions of years, highlighting the growing importance of seismic data in studying submarine volcanism,” said Schofield.
Abstract: Submarine lava flows are the most common surficial igneous rock on the Earth. However, they are inherently more difficult to study than their subaerial counterparts due to their inaccessibility. In this study, we use newly acquired 3-D (three-dimensional) seismic reflection data to document the distribution and morphology of 26 ancient, buried lava flows within the middle Eocene-aged Bight Basin Igneous Complex, offshore southern Australia. Many of these lava flows are associated with volcanoes that vary from 60 to 625 m in height and 0.3 to 10 km in diameter. Well data and seismic-stratigraphic relationships suggest that the lava flows and volcanoes were emplaced offshore in water depths of <300 m. The lava flows range from 0.5 to 34 km in length and 1 to 15 km in width and are typified by tabular and dendritic forms. This morphological variation may result from differing lava effusion rates and/or the volumes of lava erupted. We demonstrate that: (1) the dendritic flows contain complex lava distribution systems and kipukas, features never-before observed from seismic data; and (2) the distribution and morphology of the lava flows was strongly controlled by the emplacement of magmatic intrusion-induced forced folds. This suggests that magmatic intrusions may play an important role in controlling the distribution of lava flows elsewhere. Our study highlights the usefulness of seismic data in studying the manifestation of submarine volcanism, and provides quantitative data on the extent and distribution of an ancient submarine volcanic province along the southern Australian margin.