Large sand mounds beneath the North Sea have puzzled scientists for years. Now, researchers have found that these mysterious constructions have been created by a geological course of that has by no means been seen on such an enormous scale.
Seismic information and rock samples from the northern North Sea, off the coast of Norway, recommend that these miles-wide mounds sank tens of millions of years in the past, lifting up older, less-dense “ooze” beneath. The findings might assist scientists be taught extra about future carbon storage choices, the researchers wrote within the new examine, which was printed June 21 within the journal Communications Earth and Surroundings.
Researchers have recognized about these mounds buried beneath the seabed for years however have not reached a consensus concerning the constructions’ origins. Proposed explanations have included landslide deposits, sandstone pushed up from beneath, or mud pressured by way of brittle rock.
Now, utilizing a three-dimensional seismic dataset masking the northern North Sea, together with rock samples, researchers examined the mounds and the encompassing areas. They discovered that the constructions have been surrounded by older, low-density “ooze,” composed largely of the fossil stays of historic microorganisms.
The mounds have been chemically much like close by sands that seem later within the geological document. In some locations, the mounds have been linked to those sands through fractures within the rock. This implies that the mounds have been manufactured from youthful sands that sank beneath the older, lighter ooze beneath.
The sunken sands have jumbled the anticipated sample within the geological document. Often, older layers of rock are buried deeper than youthful sediment, leaving a document of the processes that formed the panorama over time.
“This discovery reveals a geological course of we’ve not seen earlier than on this scale,” examine co-author Mads Huuse, a geophysicist on the College of Manchester within the U.Okay., stated in a assertion. “What we have discovered are constructions the place dense sand has sunk into lighter sediments that floated to the highest of the sand, successfully flipping the standard layers we would count on to see and creating large mounds beneath the ocean.”
Earthquakes or modifications in strain could have brought about the sands to behave like a fluid, thus enabling it to circulation by way of fractures within the seabed and slip beneath inflexible sections of the ooze. The researchers dubbed these massive, sinking mounds “sinkites.” The ooze rafts, buoyed upward, have been named “floatites.”
“This analysis reveals how fluids and sediments can transfer round within the Earth’s crust in sudden methods,” Huuse stated.
The workforce initially studied these mounds as a attainable location for carbon dioxide storage. Earlier than starting any carbon storage efforts within the area, scientists might want to perceive how nicely and the way safely the world can maintain on to that carbon.
“Understanding how these sinkites fashioned might considerably change how we assess underground reservoirs, sealing, and fluid migration — all of that are important for carbon seize and storage,” Huuse stated.
