Geology

4 billion ago, during the Archean eon, Earth's mantle temperatures were significantly higher than they are today, according to recent numerical model calculations.

A new paper from researchers at at Johannes Gutenberg University Mainz says the Archean crust that formed under these conditions was so dense that large portions of it were recycled back into the mantle. According to the calculations, this dense primary crust would have descended vertically in drip form. In contrast, the movements of today's tectonic plates involve largely lateral movements with oceanic lithosphere recycled in subduction zones.

The findings add to our understanding of how cratons and plate tectonics, and thus also the Earth's current continents, came into being.

The Earth is about 4.6 billion years old but no rocks exist that are older than about 3.8 billion years. However, zircons that were eroded from the sedimentary rock section in the Jack Hills of western Australia, which more than 3 billion years old, were eroded from rocks as old as about 4.3 billion years. These Jack Hills zircons are the oldest recorded geological material on the planet.


Most science fiction and news stories describe Mars terraforming as a long term but simple process. You warm up the planet first, with greenhouse gases, giant mirrors, impacting comets or some such. You land humans on the surface right away and they introduce lifeforms designed to live on Mars. Over a period of a thousand years or so, life spreads over the planet and transforms it, and Mars becomes a second Earth.

The Promised Land means different things to different people. To geologists, the site of some of the largest volcanic eruptions in earth's history might fit the bill, and that means Utah is a pretty good place to be.

30 million years ago, more than 5,500 cubic kilometers of magma erupted during a one-week period near a place called Wah Wah Springs. By comparison, this eruption was about 5,000 times larger than the 1980 Mount St. Helens eruption.


Fortunately they are no longer active.

Dinosaurs were already extinct during this time period, but less well known is that 25-30 million years ago, North America was home to rhinos, camels, tortoises and even palm trees. Evidence of the ancient flora and fauna was preserved by volcanic deposits.


Experimental techniques and computer simulations have determined a new way of predicting how water dissolves crystalline structures like those found in natural stone and cement. 

In a new study, the team shows that their method is more efficient at predicting the dissolution rates of crystalline structures in water than previous methods. The research could have wide-ranging impacts in diverse areas, including water quality and planning, environmental sustainability, corrosion resistance and cement construction. 


On May 24th of 2013, a magnitude 8.3 earthquake hit deep beneath the Sea of Okhotsk, between Russia's Kamchatka Peninsula and Japan. The main shock of the earthquake was located at 610 kilometers (379 miles) depth, a rupture in the mantle far below the Earth's crust.

By inverting seismic waves that were observed during the earthquake, researchers have found that this initial shock triggered four subsequent shocks. These four shocks were magnitudes 7.8, 8.0, 7.9, and 7.9. A pressure front from the initial earthquake propagated at a speed of approximately 4.0 kilometers (2.5 miles) per second, setting off three subsequent earthquakes in a line south of the main shock. 


A new, internationally agreed radiocarbon calibration curve method will allow key past events to be dated more accurately.

The work led by Professors Paul Blackwell and Caitlin Buck from the University of Sheffield's School of Mathematics and Statistics and Professor Paula Reimer from Queen's University Belfast will lead to improved accuracy for archaeologists, environmental scientists and climate researchers who rely on radiocarbon dating to put their findings onto a reliable time-scale.

The release of the new curve will mean that more precise date estimates can be obtained than previously possible and will reduce uncertainty about the timing of major events in the history and development of humans, plants and animals and the environments in which they lived.


JHidden underneath hilly grasslands studded with ocotillos and mesquite trees in southeastern Arizona lies a world shrouded in perpetual darkness - Kartchner Caverns, a limestone cave system known for its untouched cave formations, sculpted over millennia by groundwater dissolving the bedrock and carving out underground rooms. Its passages attract tourists from all over the world. 


Two subglacial
lakes, each roughly 8-10 km2,  have been discovered 800 meters below the Greenland Ice Sheet. At one point they may have been up to three times larger than their current size. 

Subglacial lakes are likely to influence the flow of the ice sheet, impacting global sea level change. The discovery of the lakes in Greenland will also help researchers to understand how the ice will respond to changing environmental conditions.

The study, conducted at the Scott Polar Research Institute (SPRI) at the University of Cambridge, used airborne radar measurements to reveal the lakes underneath the ice sheet.


Methane has 30 times the warming effect of carbon dioxide but lacks the press awareness of its greenhouse gas cousin. 

And a new study in
Nature Geoscience has found that the seafloor off the coast of Northern Siberia is releasing more than twice the amount of methane as previously estimated - the East Siberian Arctic Shelf is venting at least 17  million tons
(teragrams) of methane into the atmosphere each year.