Agung, a volcano in Bali, had an explosive eruption in 2018. Credit: O.L. Andersen

New knowledge of Earth’s mantle helps to explain Indonesia’s explosive volcanoes

Zircons studied by the research team, photographed using cathodoluminescence, a technique that allowed the team to visualize the interiors of the crystals using a specialized scanning electron microscope. Dark circles on the zircons are the cavities left by the laser that was used to analyze the age and chemistry of the zircons.Scientists led by Michael Ackerson, a research geologist at the Smithsonian's National Museum of Natural History, provide new evidence that modern plate tectonics, a defining feature of Earth and its unique ability to support life, emerged roughly 3.6 billion years ago. The study, published May 14 in the journal Geochemical Perspective Letters, uses zircons, the oldest minerals ever found on Earth, to peer back into the planet's ancient past.The team tested more than 3,500 zircons, each just a couple of human hairs wide, by blasting them with a laser and then measuring their chemical composition with a mass spectrometer. These tests revealed the age and underlying chemistry of each zircon. Of the thousands tested, about 200 were fit for study due to the ravages of the billions of years these minerals endured since their creation. Credit: Michael Ackerson, Smithsonian.

Earth’s oldest minerals date onset of plate tectonics to 3.6 billion...

McGill Colloidal Au research team study a mineralized (gold-bearing) vein underground at the Brucejack mine. Credit: Duncan McLeish

Clues from soured milk reveal how gold veins form

The quantitative model used in the study explains the enigmatic melt degrees and layered structures observed in most cratons on Earth.

Where on Earth is all the water?

Elements of a newly discovered process in plate tectonics include a mass (rock slab weight), a pulley (trench), a dashpot (microcontinent), and a string (oceanic plate) that connects these elements to each other. In the initial state, the microcontinent drifts towards the subduction zone (Figure a). The microcontinent then extends during its journey to the subduction trench owing to the tensional force applied by the pull of the rock slab pull across the subduction zone (Figure b). Finally, the microcontinent accretes to the overriding plate and resists subduction due to its low density, causing the down-going slab to break off (Figure c). Credit: Erkan Gün/University of Toronto

Discovery of new geologic process calls for changes to plate tectonic...

Karen Heeter overlooks Yellowstone from Republic Pass on a tree coring excursion in July 2018. Credit: Grant L. Harley

Yellowstone National Park is hotter than ever

This study site was used by researchers to examine a portion of the Oman–United Arab Emirates ophiolite’s metamorphic sole. Credit: Tyler Ambrose

A closer look at the creation of a metamorphic sole

Early lineages of mammal like this large Gobiconodon from Mongolia, outcompeted the ancestors of modern mammals in the time of dinosaurs. Credit: Corbin Rainbolt

Mammals in the time of dinosaurs held each other back

A cross-section of an 18.5 million-year-old fossil of Ampelorhiza heteroxylon. Credit: Nathan Jud/Provided

18.5 million year old vine fossil identified as new species

The Earth has a layered internal structure with the crust, upper mantle, mantle transition zone, lower mantle, outer core, and inner core from the surface to the center. In the Earth’s formation stage at approximately 4.6 billion years ago, the heavy metal components were separated from silicates and sank in the magma ocean, and a core formed at the center of the Earth. In this core-mantle separation process, partitioning of noble gases between the core and mantle occurred. Credit: Taku Tsuchiya, Ehime University

A deep reservoir of primordial helium in the Earth

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