Taxonomy term

geochemistry

Fats on Neolithic pottery pinpoint climate cooling event

About 8,200 years ago, right around the time that animals such as cows and sheep were first being domesticated in the Near East for meat and milk, the planet underwent a cooling event that lasted about 160 years. How this cold snap, known as the 8.2-kiloyear event, affected early farmers has long been a mystery, as archaeological evidence from the period of the cooler and drier climate has been scant. But new research investigating fatty residues preserved on scraps of pottery found at the UNESCO World Heritage site of Çatalhöyük in Turkey is offering some clues.

05 Dec 2018

Scientists discover granite crystallizes at lower temperatures

Investigating the properties of granite has given researchers insight into how gold and other economically important ores are produced, the thermal properties of Earth’s crust, the state of magma in active volcanic regions, and how Earth’s continents formed. “The temperature of granite crystallization underpins our thinking about many of these phenomena,” researchers note in a new study in Nature. “But evidence is emerging that this temperature may not be well constrained,” added the study authors, who found that certain granites crystallize at temperatures as much as 200 degrees Celsius lower than previously thought.

26 Nov 2018

New suspect emerges in theft of Earth's surface iron

Iron is the fourth-most common element in Earth’s crust, but why there isn’t more found near the surface in continental crust has been a long-standing question among geologists. In a new study, scientists implicate an overlooked mineral culprit in the theft of iron from continental crust: garnet. But not everybody is ready to exonerate the long-implicated magnetite.

17 Aug 2018

Stable isotopes offer novel methods of disease detection

Stable isotope techniques developed by geoscientists are being applied to studies of human health, and one in particular has shown promise as an improved way to determine bone loss, a problem for astronauts, as well as those on bed rest and aging populations here on Earth. 
08 Jan 2018

The path to gypsum is four steps long

Drywall and plasters made from both natural and manufactured gypsum are commonly used in home and building construction around the world, in part because of gypsum’s widespread availability. Despite its abundance, and its seemingly simple makeup, however, relatively little is known about how the calcium sulfate mineral forms in nature. In a recent study, researchers have shed new light on the multi-stage process by which gypsum grows — and the findings could help develop more efficient ways to manufacture the material.

08 Nov 2016

Cave dripwater records wildfires

Water seeps through soil and bedrock before dripping from the roof of a cave and carries with it elements of the outside world and its climate history. That is why speleothems, cave structures formed via precipitation, can be studied as climate proxies. New research suggests that the chemistry of the cave dripwater can also contain the signature of wildfires that burned outside the cave, on the ground above the cave’s roof, yielding a more complex picture of the past.

27 Oct 2016

Zircons hold clues to early Earth

Not much is known about the first 500 million years of Earth’s history, between 4.5 billion and 4 billion years ago. We know the interior of the planet was hotter than it is today, and that Earth’s surface experienced intense meteorite bombardment, which left the surface pocked with magma-filled craters. But with no rock record available from this period — the oldest rocks are 4.04 billion years old — scientists must look to the composition of tiny grains of the mineral zircon to provide clues about Earth during the Hadean Eon. But where did the zircons come from?

09 Sep 2016

Did crustal chemistry buoy Western Plains?

The mighty mountains of the American West may captivate artists and adventurers with their rugged allure, but it’s the humble High Plains that intrigue certain geologists. For decades, scientists have puzzled over the origins of this vast plateau, which stretches for more than 500 kilometers east of the Rockies.
 
12 Jul 2015

New nationwide soil map available online

The U.S. Geological Survey (USGS) recently completed a seven-year soil-mapping project detailing the mineralogy and geochemistry of soils across the lower 48 U.S. states. Bill Cannon, an emeritus scientist at the USGS in Reston, Va., and co-author of the report, which was published in 2014, discussed the effort last October at the Geological Society of America’s annual meeting in Vancouver, B.C.

13 Feb 2015

Searching for evidence of ancient subduction

For billions of years, portions of Earth’s rigid surface have dipped and sunk along plate boundaries to be recycled back into the mantle below. Determining when the process of subduction began — a fundamental step in Earth’s physical, and possibly biological, evolution — has proved difficult for geoscientists due to the challenges of interpreting evidence from the few remnants of early Earth that remain. In a recent study, researchers have now proposed a new approach for identifying ancient subduction zones that could help tackle the longstanding question.
 

06 Jul 2014

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