There is a saying that we know more about Mars than we do about Earth’s oceans. I am not sure how true that is, but our knowledge of the ocean floor is surely the latest addition to geoscience. Recently, a group of scientists has undertaken an ambitious global project to map the ocean floor in high resolution. Another group is mapping subglacial Greenland using geophysical surveys, which are often applied to petroleum basins. Let’s take a look.
Rasoul Sorkhabi
Editor, Core Elements
Mapping The Global Seafloor by 2030
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Mapping of the ocean floor during the 1950s led to the discovery of mid-ocean ridges, subduction trenches, and transform faults—all part of plate tectonics. But, decades later, the seafloor still remains largely unknown.
Driving the news:EOSand BBC both recently covered the progress of the Seabed 2030 project.
About the project:
Seabed 2030 was launched in 2017 to map the global ocean floor with modern technologies.
This program aims to map and image all seafloor features larger than 100 meters by 2030.
When the project began, only 6 percent of the ocean floor was mapped in high resolution. Today, Seabed 2030 has increased this proportion to 25 percent. It hopes to complete the remaining 75 percent over the next six years.
All Seabed 2030 data are uploaded to the GEBCO grid of the seafloor, which is open access.
Players and partners: Seabed was initially founded by Nippon Foundation (a Japanese nonprofit) and the General Bathymetric Chart of the Oceans (GEBCO).
Over time, other organizations have joined:
In 2023, the U.K.-based remote sensing company ARGANS and the Japanese Coast Guard donated significant datasets.
The U.S. company Saildrone partnered with Seabed 2030 to promote the use of uncrewed hydrographic vessels. Saildrone’s surveyor drone is powered by wind and solar energy and can collect data to water depths of 7000 meters.
Why it matters: High-resolution ocean floor maps are important for:
Sea navigation
Laying underwater pipelines and cables
Fisheries management and conservation
Marine habitats and biodiversity
Ocean currents and water mixing
Geology and geography of ocean floor features
Resource exploration
Go deeper: Learn more from Seabed 2030’s official website and this YouTube videoclip.
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With an area of 2.2 million square kilometers, Greenland is the largest island in the world. The Greenland Ice Sheet covers 79 percent of the island, located between latitudes 59 and 83 North. Its subglacial geology has puzzled geologists for years.
Context:
In 2009, Peter Dawes of the Geological Survey of Denmark and Greenland published the bedrock geologic map of Greenland, which is still widely used today.
This geologic map of Greenland was based on rock exposures on its ice-free margins and their interpolation to subglacial inland.
What’s new: Recently, NASA’s Joseph MacGregor and colleagues have employed geophysical datasets to map the geological provinces beneath the Greenland Ice Sheet. These scientists integrated 19 datasets from seismic, gravity, and magnetic surveys and correlated geophysical signals of the mapped rock exposures to subglacial rocks.
Major findings:
Greenland is a Precambrian craton. The new map has divided Greenland’s bed rock geology into distinct geological provinces, from the Ketilidian orogen and North Atlantic craton in the south to the Franklinian Basin in the north.
Three newly delineated geological provinces did not match with the outcrop geology at the island’s margin.
The new study identified dozens of long and near-parallel valleys under the ice.
In some places, geophysical anomalies and province boundaries are close to the location of faster ice flow.
Why it matters:
Creating a detailed geologic map of Greenland is important to better understand the geologic history of the island, mineral resources, and geologic processes such as geothermal heat flux.
Geologically young provinces with rough topographic surfaces will probably have higher heat flow.
The Greenland Ice Sheet’s flow and discharge into the surrounding oceans are influenced by the island’s bedrock conditions.
The study offers a new methodological case to map subglacial geology in other parts of the world.
Go deeper: Read the full article published in Geophysical Research Letterhere.
Quiz of the Week
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Thank you to all who submitted answers to last week’s quiz!
As a reminder, the question was: What are the top three deepest canyons (gorges) in the world? Please list name, location, and depth. (Hint: The Grand Canyon is not one of them).
We received several great responses, but I’ll share thoughts from Robert Gunn, who gave the most comprehensive answer:
A gorge (from the French for throat), may be in a canyon (from Mexican Spanish for long tube) if its width at the base is almost as wide as at its rim.
Yarlung Tsangpo Grand Gorge in Tibet, 19,714 ft deep
Kali Gandaki Gorge in Nepal, 18,278 ft deep
Colca Canyon in Peru, 11,155 ft in deep
(Note: The Grand Canyon is 6,093 ft deep)
Now, let’s move on to this week’s question: What are the three deepest ocean floor features? Please list the name, water depth, ocean name, and tectonic feature or setting.
Please send your response by October 24 to editorial@aapg.org (subject line: Core Elements Quiz)
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