Amazing stuff!
The author of the Perspective abstract below is obsessed with Global Warming/Climate Change: "The movement of tectonic plates—massive slabs of rock—over Earth’s surface controls the planet’s habitability by sustaining the carbon cycle that regulates the climate" (The first sentence of the abstract) I have serious doubts that this is correct!
From the Perspective abstract:
"The movement of tectonic plates—massive slabs of rock—over Earth’s surface controls the planet’s habitability by sustaining the carbon cycle that regulates the climate [???] and stabilizes liquid water at the surface .
It also facilitates efficient planetary heat loss, thereby maintaining convection in Earth’s core and the generation of a magnetic field. The presence of a magnetosphere—a space around Earth dominated by its magnetic field—provides shielding from solar and cosmic radiation and mediates the loss of atmospheric gas into space. Deciphering plate motions in Earth’s early history can thus hint at how the planet looked several billion years ago. On page 1278 of this issue, Brenner et al. (2) report differential plate motion 3.5 billion years (Ga) ago by recovering ancient magnetic field records from rocks in Australia. This may provide clues to the nature of early tectonic motions and their role in sustaining habitable conditions."
It also facilitates efficient planetary heat loss, thereby maintaining convection in Earth’s core and the generation of a magnetic field. The presence of a magnetosphere—a space around Earth dominated by its magnetic field—provides shielding from solar and cosmic radiation and mediates the loss of atmospheric gas into space. Deciphering plate motions in Earth’s early history can thus hint at how the planet looked several billion years ago. On page 1278 of this issue, Brenner et al. (2) report differential plate motion 3.5 billion years (Ga) ago by recovering ancient magnetic field records from rocks in Australia. This may provide clues to the nature of early tectonic motions and their role in sustaining habitable conditions."
From the editor's summary and abstract:
"Editor’s summary
Plate tectonics is a global recycling process that underpins most of Earth’s systems. Its onset remains an open question because of sparse early geologic records. Brenner et al. collected paleomagnetic data from approximately 3.4 billion-year-old rocks in Western Australia and compared them with existing data from rocks of the same age in South Africa (see the Perspective by Nichols). They detected diverging paleolatitudes, two crustal blocks moving differently around the same magnetic pole. The rate of motion is consistent with aspects of modern plate tectonics but could reflect an earlier style. This plate motion was occurring against the backdrop of the oldest known geomagnetic reversal, which was also discovered from these data.
Abstract
Whether early Earth had a mobile lithosphere and plate tectonics is debated. We present paleomagnetic data quantifying differential motion between lithospheric blocks at ~3.48 billion years ago (Ga). This manifested as
centimeters per year latitudinal motion of the East Pilbara Craton (Western Australia) across high latitudes, whereas the Barberton Greenstone Belt (South Africa) was stationary at low latitudes. Comparison of this plate motion with candidate analogs suggests either rapid collisional plate tectonics (i.e., an “active-lid”) or an episodically mobile lithosphere. We also document the oldest known geomagnetic reversal at ~3.46 Ga, consistent with an axial dipolar dynamo that reversed less frequently than today’s. The existence and rates of these surface and core geophysical phenomena provide geodynamic context to Earth’s early geophysical and biological evolution."
Ancient rocks reveal early plate motions (Perspective, no public access)
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