Geology

Two studies  presented today at the Goldschmidt 2014 geochemistry conference in Sacramento show that the movement rate of plates carrying the Earth's crust may not be constant over time. That could provide a new explanation for the patterns observed in the speed of evolution and has implications for the interpretation of climate models.  

The Earth's continental crust is an archive of Earth's history and it is the basis for studies on rock formation, the atmosphere and the fossil record - but it is not clear when and how regularly crust formed since the beginning of Earth history 4.5 billion years ago. 


There have been times in our geological history when CO2 levels were 10X what they are today, yet warming was only slightly higher.

Unlike what you often read in simplistic media accounts, there are a lot of variables in climate and weather and temperature. It takes a lot of things going wrong to turn Earth into Venus and we have never come close. 

At the Goldschmidt geochemistry conference in Sacramento, geochemists discussed one such period, but they say we just got lucky - a vast mountain range formed in the middle of the ancient supercontinent, Pangea. 


How were the earth and the moon formed? A giant impact between Earth's ancestor and a planet-sized body occurred

At the Goldschmidt Geochemistry Conference in Sacramento, researchers from the University of Lorraine say that occurred 40 million years after the start of solar system formation, which makes the earth around 60 million years older than previously thought. 


Since October 2013,  the rate of earthquakes in Oklahoma has been up by about 50 percent, which has geologists thinking about the chance for a damaging quake in central Oklahoma.

A joint statement by the U.S. Geological Survey and Oklahoma Geological Survey says that 183 earthquakes of magnitude 3.0 or greater occurred in Oklahoma from October 2013 through April 14, 2014. The long-term average from 1978 to 2008 showed only two magnitude 3.0 or larger earthquakes per year. The increased number of small and moderate shocks has led them to predict a higher likelihood of future, damaging earthquakes for central and north-central Oklahoma.

Can using a well move a mountain? It will if the well is big enough.

Winter rains and summer groundwater pumping in California's Central Valley make the Sierra Nevada and Coast Mountain Ranges sink and rise.

How much? A few millimeters each year. That doesn't sound like a lot but it creaes stress on the state's faults that could increase the risk of an earthquake.

Gradual depletion of the Central Valley aquifer due to groundwater pumping also raises these mountain ranges by a similar amount - about the thickness of a dime - each year, according to a new paper in Nature. That cumulative rise over the past 150 years could be up to 6 inches, according to calculations by the geophysicists. 


A new discovery in the study of how lava dome volcanoes erupt may help predict how a volcanic eruption will behave.

Volcanologists say a process called frictional melting plays a role in determining how a volcano will erupt, by dictating how fast magma can ascend to the surface, and how much resistance it faces en-route.

The process occurs in lava dome volcanoes when magma and rocks melt as they rub against each other due to intense heat. This creates a stop start movement in the magma as it makes its way towards the earth's surface. The magma sticks to the rock and stops moving until enough pressure builds up, prompting it to shift forward again, a process called stick-slip. 


University of California, Berkeley, geologist William Dietrich pioneered the application of airborne LIDAR, light detection and ranging, to map mountainous terrain, stripping away the vegetation to see the underlying ground surface - but he still couldn't see what was under the surface: the depth of the soil, the underlying weathered rock and the deep bedrock.

He and geology graduate student Daniella Rempe have now proposed a method to determine these underground details without drilling, potentially providing a more precise way to predict water runoff, the moisture available to plants, landslides and how these will respond to climate change.


The oldest sections of transform faults, such as the North Anatolian Fault Zone and the San Andreas Fault, produce the largest earthquakes, putting important limits on the potential seismic hazard for less mature parts of fault zones, according to a new presentation ("Fault-Zone Maturity Defines Maximum Earthquake Magnitude") at the Seismological Society of America 2014 Annual Meeting in Anchorage.


When and where did the ancient Iapetus Ocean suture (the most fundamental Appalachian structure) form? Is part of New England made up of ancient African-derived rocks? What is the Moretown terrane? 

Mountain-building events, called "orogenies," in the northern U.S. Appalachia record the closure of the Iapetus Ocean, an ancient precursor to the Atlantic. The Iapetus separated continental fragments of ancestral North America and Africa more than 450 million years ago.


Parts of the landscape underlying the massive Greenland ice sheet may have been undisturbed for almost 3 million years, since the island became completely ice-covered, say researchers who based their discovery on an analysis of the chemical composition of silts recovered from the bottom of an ice core more than 3,000 meters long. 

The find suggests "pre-glacial landscapes can remain preserved for long periods under continental ice sheets." 

In the time since the ice sheet formed "the soil has been preserved and only slowly eroded, implying that an ancient landscape underlies 3,000 meters of ice at Summit, Greenland," they conclude.