Friday, November 30, 2012

Grand Canyon Age

I just finished reading a fascinating article on the Grand Canyon's age.  Most recently scientists mostly agree that the Grand Canyon is much older than previously thought.  

 Read on for more details...


Grand Canyon as Old as the Dinosaurs: Dates for Carving of Western Grand Canyon Pushed Back 60 Million Years

ScienceDaily (Nov. 29, 2012) — An analysis of mineral grains from the bottom of the western Grand Canyon indicates it was largely carved out by about 70 million years ago -- a time when dinosaurs were around and may have even peeked over the rim, says a study led by the University of Colorado Boulder.
The new research pushes back the conventionally accepted date for the formation of the Grand Canyon in Arizona by more than 60 million years, said CU-Boulder Assistant Professor Rebecca Flowers. The team used a dating method that exploits the radioactive decay of uranium and thorium atoms to helium atoms in a phosphate mineral known as apatite, said Flowers, a faculty member in CU-Boulder's geological sciences department.
The helium atoms were locked in the mineral grains as they cooled and moved closer to the surface during the carving of the Grand Canyon, she said. Temperature variations at shallow levels beneath Earth's surface are influenced by topography, and the thermal history recorded by the apatite grains allowed the team to infer how much time had passed since there was significant natural excavation of the Grand Canyon, Flowers said.
"Our research implies that the Grand Canyon was directly carved to within a few hundred meters of its modern depth by about 70 million years ago," said Flowers. A paper on the subject by Flowers and Professor Kenneth Farley of the California Institute of Technology was published online Nov. 29 in Science magazine.
Flowers said there is significant controversy among scientists over the age and evolution of the Grand Canyon. A variety of data suggest that the Grand Canyon had a complicated history, and the entire modern canyon may not have been carved all at the same time. Different canyon segments may have evolved separately before coalescing into what visitors see today.
In a 2008 study, Flowers and colleagues showed that parts of the eastern section of the Grand Canyon likely developed some 55 million years ago, although the bottom of that ancient canyon was above the height of the current canyon rim at that time before it subsequently eroded to its current depth.
Over a mile deep in places, Arizona's steeply sided Grand Canyon is about 280 miles long and up to 18 miles wide in places. Visited by more than 5 million people annually, the iconic canyon was likely carved in large part by an ancestral waterway of the Colorado River that was flowing in the opposite direction millions of years ago, said Flowers.
"An ancient Grand Canyon has important implications for understanding the evolution of landscapes, topography, hydrology and tectonics in the western U.S. and in mountain belts more generally," said Flowers. The study was funded in part by the National Science Foundation.
Whether helium is retained or lost from the individual apatite crystals is a function of temperatures in the rocks of Earth's crust, she said. When temperatures of the apatite grains are greater than 158 degrees Fahrenheit, no helium is retained in the apatite, while at temperatures below 86 degrees F, all of the helium is retained.
"The main thing this technique allows us to do is detect variations in the thermal structure at shallow levels of the Earth's crust," she said. "Since these variations are in part induced by the topography of the region, we obtained dates that allowed us to constrain the timeframe when the Grand Canyon was incised."
Flowers and Farley took their uranium/thorium/helium dating technique to a more sophisticated level by analyzing the spatial distribution of helium atoms near the margin of individual apatite crystals. "Knowing not just how much helium is present in the grains but also how it is distributed gives us additional information about whether the rocks had a rapid cooling or slow cooling history," said Flowers.
There have been a number of studies in recent years reporting various ages for the Grand Canyon, said Flowers. The most popular theory places the age of the Grand Canyon at 5 million to 6 million years based on the age of gravel washed downstream by the ancestral Colorado River. In contrast, a 2008 study published in Science estimated the age of the Grand Canyon to be some 17 million years old after researchers dated mineral deposits inside of caves carved in the canyon walls.
Paleontologists believe dinosaurs were wiped out when a giant asteroid collided with Earth 65 million years ago, resulting in huge clouds of dust that blocked the sun's rays from reaching Earth's surface, cooling the planet and killing most plants and animals.
Because of the wide numbers of theories, dates and debates regarding the age of the Grand Canyon, geologists have redoubled their efforts, said Flowers. "There has been a resurgence of work on this problem over the past few years because we now have some new techniques that allow us to date rocks that we couldn't date before," she said.
While the dating research for the new study was done at Caltech, Flowers recently set up her own lab at CU-Boulder with the ability to conduct uranium/thorium/helium dating.
"If it were simple, I think we would have solved the problem a long time ago," said Flowers. "But the variety of conflicting information has caused scientists to argue about the age of the Grand Canyon for more than 150 years. I expect that our interpretation that the Grand Canyon formed some 70 million years ago is going to generate a fair amount of controversy, and I hope it will motivate more research to help solve this problem."
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The above story is reprinted from materials provided byUniversity of Colorado at Boulder.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
  1. R. M. Flowers and K. A. Farley. Apatite 4He/3He and (U-Th)/He Evidence for an Ancient Grand Canyon.Science, 29 November 2012 DOI: 10.1126/science.1229390
 APA

 MLA
University of Colorado at Boulder (2012, November 29). Grand Canyon as old as the dinosaurs: Dates for carving of western Grand Canyon pushed back 60 million years.ScienceDaily. Retrieved November 30, 2012, from http://www.sciencedaily.com­/releases/2012/11/121129143301.htm
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
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Tuesday, November 27, 2012

The Antarctic

With the onset of colder weather, that brought me to think about how cold it is in the Antarctic.  Below is the link to BBC Nature's Antarctic Ecozone Homepage.  It has all sorts of pictures, videos, etc.

Antarctic Ecozone Site
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Monday, November 19, 2012

The Fracking Debate Continues...

As per our relatively recent discussions about hydraulic fracturing, this article from the Wall Street Journal will help shed some light on the fierce debate between pro- and anti-fracking sides of the argument.


Drillers Begin Reusing 'Frack Water'

Energy Firms Explore Recycling Options for an Industry That Consumes Water on Pace With Chicago

MORE IN TECH »

By ALISON SIDER, RUSSELL GOLD and BEN LEFEBVRE

Companies are racing to find ways to recycle the water used in hydraulic fracturing, chasing an emerging market that could be worth billions of dollars.
From energy industry giants Halliburton Corp. HAL +4.10% and Schlumberger Ltd.SLB +3.62% to smaller outfits such as Ecologix Environmental Systems LLC, companies are pursing technologies to reuse the "frack water" that comes out of wells after hydraulic fracturing, or "fracking"—the process of using highly pressured water and chemicals to coax oil and gas out of shale-rock formations.
[image]Agence France-Presse/Getty Images
At fracking sites such as this one in Pennsylvania, companies have to haul water hundreds of miles to the nearest injection wells.
While the recycled water can't currently be cleaned up enough for drinking or growing crops, it can be cleaned of chemicals and rock debris and reused to frack additional wells, which could sharply cut the costs that energy companies face securing and disposing of water.
Some companies are finding it is still cheaper in many parts of the U.S. to inject the wastewater deep underground instead of cleaning it, which has slowed adoption of recycling technology. But experts say that is likely to change as fracking grows.
At Schlumberger, which predicts that a million new wells will be fracked around the world between now and 2035, reducing freshwater use "is no longer just an environmental issue—it has to be an issue of strategic importance," Salvador Ayala, vice president of well-production services, told a recent conference.
Though fracking has brought U.S. oil production to its highest level in more than 14 years and produced a glut of natural gas, it requires huge amounts of water, raising costs for energy companies and spurring opposition from environmental groups at a time when some states are suffering through droughts.
It takes between 70 billion to 140 billion gallons of water to frack 35,000 wells a year, the industry's current pace, according to a 2011 report by the Environmental Protection Agency. That is about the same amount consumed every year by Chicago or Houston—and the price tag for securing that much water can be substantial.
In North Dakota's Bakken Shale, one of the current fracking hot spots, fresh water delivered to a drilling site costs between 10 and 14 cents per gallon, according toContinental Resources Inc., CLR +4.24% an Oklahoma City-based oil driller. Water alone can cost upward of $400,000 per fracturing attempt—and Continental plans more than 200 next year in North Dakota.
Energy companies are also struggling with how to get rid of the tainted water that comes out of fractured wells; the fluid, which contains a mix of chemicals and salts, must be taken to a licensed disposal facility.
Companies are researching moving away from using water entirely to fracture rock, with efforts aimed at using propane gel and even compressed air. Moving away from liquids entirely, however, is still several years away—if early laboratory work can be successfully applied in the field.
While the cost of getting rid of the millions of gallons varies from state to state, it can be substantial. In Texas, where there are plenty of emptied-out oil fields, companies can often inject the water into spent wells, which are generally older conventional wells that have been converted to accept oil-field wastewater.
But in places such as Pennsylvania, companies have to haul the water hundreds of miles to the nearest injection wells. Injection wells pump the untreated oil-field liquids deep underground into porous rock formations for permanent disposal. There are less than 10 working injection wells in Pennsylvania, so most of its wastewater is carried by trucks into Ohio.
These injection wells are controversial after being linked by some scientists and state officials to minor earthquakes. The injected liquids are essentially thought to lubricate faults and accelerate movement that causes tremors. Ohio only recently began issuing permits for new injection wells, after imposing rules to prevent tremors.
In the Northeast, oil companies have to pay up to $8 per 42-gallon barrel to contractors to haul wastewater for disposal elsewhere, said Jeanie Oudin, an analyst with energy consulting firm Wood Mackenzie. She said operators have reported recycling—which eliminates the cost of disposal and the cost of acquiring fresh water for fracking—can cut costs by as much as $2 per barrel in some areas when done on site, which could equate to a $200,000 savings over the lifetime of a typical well.
"It's a multibillion-dollar business that someone is going to capture and reap the benefits of," Ms. Oudin said of the sector and its potential annual size.
Chesapeake Energy Corp. CHK +5.11% has begun recycling 100% of the water it retrieves from wells in northern Pennsylvania. In addition to cutting the company's costs, recycling reduces the number of trucks on the road ferrying clean water to drilling sites, a sore point for local residents, said spokesman Michael Kehs.
After a well is fracked, contractors typically clean the water that flows back out of the well by filtering it or adding a chemical that attracts small solid particles, making it easier to remove these contaminants. Some companies treat water at the well, while others bring it to a facility built nearby.
Fourteen percent of water used to frack a well in central Pennsylvania is now recycled, up from less than 1% two years ago, according to the Susquehanna River Basin Commission, which monitors water usage.
Clay Terry, strategic business manager of Halliburton's Water Solutions unit, said operators in areas such as Texas have been slow to embrace recycling, largely because using injection wells there is fairly inexpensive. But there are growing economic benefits to recycling water, he said, and political ones, too.
"As the political and regulatory environment continues to shift toward protecting and constraining the use of finite resources," he said, "the operating community will continue to move to alternative sources."
The interest in water recycling is creating opportunities for small companies such as Select Energy Services LLC, a closey held Houston firm that said it has had a rapid rise in demand for its water-recycling services. It currently has full-scale operations in four areas including North Dakota and Colorado, up from one at the end of last year, as more companies examine recycling frack water.
Ecologix, an Alpharetta, Ga., recycling company, claims its service can cost as much as 80% less than injecting wastewater into a disposal well. It is building new facilities in west Texas to purify 31,000 barrels a day of wastewater after having earlier sold all of its recycling units to Halliburton.
"Hopefully, we'll mend the dispute between environmentalists and oil companies by answering the wish list of both," said Chief Executive Eli Gruber.
Write to Alison Sider at alison.sider@dowjones.com, Russell Gold atrussell.gold@wsj.com and Ben Lefebvre at ben.lefebvre@dowjones.com
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