Harvard researchers provide stronger proof of plate tectonics billions of years ago – Harvard Gazette
New evidence points to the role of plate tectonics in early Earth’s release of internal heat and the swapping of geomagnetic poles.
Illustration by Alec Brenner
The surprising thing is not so much that Creationists ever existed. Given the power of the Medieval Christian and Islamic religions to coerce the population and force on them simplistic dogma from the ignorant and fearful infancy of our species, and to supress contradicting science, it would have been surprising it they hadn't existed in those days. The really surprising thing is that, despite the massive amount of information which flatly contradicts the childish superstitions and the advanced technological societies in which most of them live, there are actual adults, leading otherwise normal lives, who still believe that childish nonsense.
There really are grown adults who believe Earth was magicked into existence, as is. less than 10,000 years ago!
And these ignorant people exist despite evidence such as this paper, that there were continental movements, known to geologists as plate tectonics, billions of years before they believe Earth was magicked up by a spell from an invisible magician, the existence of which has never been explained, let alone demonstrated with evidence, and the
modus operandum which has never been observed.
And, if that wasn't bad enough for the Creation cult, the paper even alludes to the geological clock that has been recording the magnetic reversals of Earth that have occurred 183 times in the last 83 million years and perhaps several hundred times in the past 160 million years,
according to NASA.
The scientists led by Harvard geologists, Alec Brenner and Roger Fu, point out that the stability of the early Earth, where basically the same tectonic forces were working as are working still, means the conditions were conducive to the appearance and evolution of self-replicating systems we call life.
As the
Harvard Gazette article by Juan Siliezar explains:
New research analyzing pieces of the most ancient rocks on the planet adds some of the sharpest evidence yet that Earth’s crust was pushing and pulling in a manner similar to modern plate tectonics at least 3.25 billion years ago. The study also provides the earliest proof of when the planet’s magnetic north and south poles swapped places. The two results offer clues into how such geological changes may have resulted in an environment more conducive to the development of life on the planet.
The work, described in PNAS and led by Harvard geologists Alec Brenner and Roger Fu, focused on a portion of the Pilbara Craton in Western Australia, one of the oldest and most stable pieces of the Earth’s crust. Using novel techniques and equipment, the researchers show that some of the Earth’s earliest surface was moving at a rate of 6.1 centimeters per year and 0.55 degrees every million years.
That speed more than doubles the rate the ancient crust was shown to be moving in a previous study by the same researchers. Both the speed and direction of this latitudinal drift leaves plate tectonics as the most logical and strongest explanation for it.
“There’s a lot of work that seems to suggest that early in Earth’s history plate tectonics wasn’t actually the dominant way in which the planet’s internal heat gets released, as it is today, through the shifting of plates,” said Brenner, a Ph.D. candidate in the Graduate School of Arts and Sciences and a member of Harvard’s Paleomagnetics Lab. “This evidence lets us much more confidently rule out explanations that don’t involve plate tectonics.”
Geologists Alec Brenner and Roger Fu, focused on a portion of the Pilbara Craton in Western Australia, one of the oldest and most stable pieces of the Earth’s crust.
Photo by Roger Fu
In the paper, the scientists also describe what’s believed to be the oldest evidence of when Earth reversed its geomagnetic fields, meaning the magnetic North and South Pole flipped locations. This type of flip-flop is a common occurrence in Earth’s geologic history, with the poles reversing 183 times in the last 83 million years and perhaps several hundred times in the past 160 million years, according to NASA.
The reversal tells a great deal about the planet’s magnetic field 3.2 billion years ago. Key among the implications is that the magnetic field was likely stable and strong enough to keep solar winds from eroding the atmosphere. This insight, combined with the results on plate tectonics, offers clues to the conditions under which the earliest forms of life developed.
It paints this picture of an early Earth that was already really geodynamically mature. It had a lot of the same sorts of dynamic processes that result in an Earth that has essentially more stable environmental and surface conditions, making it more feasible for life to evolve and develop.
Alec R. Brenner lead author
Department of Earth and Planetary Sciences
Harvard University, Cambridge, MA, USA.
Evidence of when plate tectonics started is hard to come by because the oldest pieces of crust are thrust into the interior mantle, never to resurface. Only 5 percent of all rocks on Earth are older than 2.5 billion years old, and no rock is older than about 4 billion years.
Finally being able to reliably read these very ancient rocks opens up so many possibilities for observing a time period that often is known more through theory than solid data. Ultimately, we have a good shot at reconstructing not just when tectonic plates started moving, but also how their motions — and therefore the deep-seated Earth interior processes that drive them — have changed through time.
Professor Roger R. Fu,
Department of Earth and Planetary Sciences,
Harvard University, Cambridge, MA. USA
Using magnetometers, demagnetizing equipment, and the Quantum Diamond Microscope — which images the magnetic fields of a sample and precisely identifies the nature of the magnetized particles — the researchers created a suite of new techniques for determining the age and way the samples became magnetized. This allows the researchers to determine how, when, and in which direction the crust shifted as well as the magnetic influence coming from Earth’s geomagnetic poles.
The Quantum Diamond Microscope was developed in a collaboration between Harvard researchers in the Departments of Earth and Planetary Sciences (EPS) and of Physics.
For future studies, Fu and Brenner plan to keep their focus on the Pilbara Craton while also looking beyond it to other ancient crusts around the world. They hope to find older evidence of modern-like plate motion and when the Earth’s magnetic poles flipped.
In the abstract to their published open access paper in
PNAS, the scientists say:
Significance
The modern Earth is geologically dynamic. Convection in its rocky mantle drives plate tectonics that reshapes its surface, and currents inside its metallic core generate a strong planetary magnetic field. However, it is uncertain whether these processes had begun to shape Earth in its deep past. Our measurements of magnetic signals preserved in 3.25-billion-year-old rocks provide the earliest quantitative evidence of both rapidly moving crust—a hallmark of plate tectonics—and a stable ancient magnetic field that episodically alternated polarity. These observations suggest that the early Earth was remarkably geologically mature from its surface to its deep interior, potentially contributing to stable surface conditions for the evolution of early life.
Abstract
The paleomagnetic record is an archive of Earth’s geophysical history, informing reconstructions of ancient plate motions and probing the core via the geodynamo. We report a robust 3.25-billion-year-old (Ga) paleomagnetic pole from the East Pilbara Craton, Western Australia. Together with previous results from the East Pilbara between 3.34 and 3.18 Ga, this pole enables the oldest reconstruction of time-resolved lithospheric motions, documenting 160 My of both latitudinal drift and rotation at rates of at least 0.55°/My. Motions of this style, rate, and duration are difficult to reconcile with true polar wander or stagnant-lid geodynamics, arguing strongly for mobile-lid geodynamics by 3.25 Ga. Additionally, this pole includes the oldest documented geomagnetic reversal, reflecting a stably dipolar, core-generated Archean dynamo.
Just another example there of how Creationism is refuted quite incidentally, simply by revealing the real world evidence with which it is of course entirely inconsistent simply because the people who made up the origin myths in the Bronze Age were entirely ignorant of the science. Incidentally, it's also an example of the way different strands of evidence mesh so neatly to support the idea that life originated on Earth several billion years ago, just as you would expect if the current theories were correct.
Even more amazing than the fact the otherwise normal people believe the childish Bronze Age Creation myths despite this sort of refutation, is that these same people are prepared to perform the most idiotic mental gymnastics to dismiss them, as though being ignorant of scientific evidence is something to take great pride in, because their mummies and daddies were also ignorant of them.
Thank you for sharing!
