Amazing stuff!
We do not even yet understand the geology of our planet very well, but we are inundated on a daily basis with a barrage of climate change propaganda and demagoguery! Even many scientists can not resist to chime in for more money or for lack of genius or being like idiot savants (Very peculiar Wikipedia eliminated or omitted this famous term. A case of political correctness?)!
"... scientists uncovered evidence of an ancient seafloor that sank deep into Earth during the age of dinosaurs, challenging existing theories about Earth's interior structure. Located in the East Pacific Rise (a tectonic plate boundary on the floor of the southeastern Pacific Ocean), this previously unstudied patch of seafloor sheds new light on the inner workings of our planet and how its surface has changed over millions of years. ...
They found an unusually thick area in the mantle transition zone, a region located between about 410 and 660 kilometers below the Earth's surface. The zone separates the upper and lower mantles, expanding or contracting based on temperature. The team believes that the newly discovered seafloor may also explain the anomalous structure of the Pacific Large Low Shear Velocity Province (LLSVP)—a massive region in Earth's lower mantle—as the LLSVP appears to be split by the slab. ...
They found an unusually thick area in the mantle transition zone, a region located between about 410 and 660 kilometers below the Earth's surface. The zone separates the upper and lower mantles, expanding or contracting based on temperature. The team believes that the newly discovered seafloor may also explain the anomalous structure of the Pacific Large Low Shear Velocity Province (LLSVP)—a massive region in Earth's lower mantle—as the LLSVP appears to be split by the slab. ...
What the team found surprised them—material was moving through Earth's interior much more slowly than previously thought. Wang believes that the unusual thickness of the area the team discovered suggests the presence of colder material in this part of the mantle transition zone, hinting that some oceanic slabs get stuck halfway down as they sink through the mantle. ..."
From the abstract:
"The Pacific large low-shear-velocity province (LLSVP), as revealed by cluster analysis of global tomographic models, hosts multiple internal anomalies, including a notable gap (~20° wide) between the central and eastern Pacific. The cause of the structural gap remains unconstrained. Directly above this structural gap, we identify an anomalously thick mantle transition zone east of the East Pacific Rise, the fastest-spreading ocean ridge in the world, using a dense set of SS precursors. The area of the thickened transition zone exhibits faster-than-average velocities according to recent tomographic images, suggesting perturbed postolivine phase boundaries shifting in response to lowered temperatures. We attribute this observation to episodes of Mesozoic-aged (250 to 120 million years ago) intraoceanic subduction beneath the present-day Nazca Plate. The eastern portion of the Pacific LLSVP was separated by downwelling because of this ancient oceanic slab. Our discovery provides a unique perspective on linking deep Earth structures with surface subduction."
UMD Geologists Discover Ancient Sunken Seafloor From Dinosaur Era (original news release) "Zone Beneath Pacific Ocean Reveals How ‘Recycling’ Deep Within the Earth May Influence Surface Features"
A map depicting the region where the discovery of an ancient seafloor was made.
Fig. 5. Interpreted evolution of the SEPR anomaly.
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