[meteorite-list] Earth Has 'Blueberries' Like Mars

[Ron Baalke]

News and Public Relations
University of Utah
Salt Lake City, Utah

Media Contacts:

Marjorie Chan, chair and professor of geology and geophysics
Available afternoon June 15-morning June 17 only via cellular, 
sporadic availability via cellular June 18-July 4, then at office July 5 
onward by phone (801) 581-7162 or 581-6553 or email 
machan at mines.utah.edu

Brenda Beitler, geology graduate student
Available June 14-16 in office (801) 581-7089 or via cellular, 
bbeitler at mines.utah.edu. Sporadic availability via cellular June 17-
20.

Bill Parry, emeritus professor of geology and geophysics
Office (801) 581-6217, wparry at comcast.net or 
bparry at mines.utah.edu. Unavailable June 20-July 4.

Lee Siegel, science news specialist, University of Utah Public Relations
office (801) 581-8993, leesiegel at ucomm.utah.edu

June 16, 2004

Earth Has 'Blueberries' Like Mars

'Moqui Marbles' Formed in Groundwater in Utah's National Parks

Even before marble-shaped pebbles nicknamed "blueberries" were 
discovered on Mars by the Opportunity rover, University of Utah 
geologists studied similar rocks in Utah's national parks and 
predicted such stones would be found on the Red Planet.

In a study published in the June 17 issue of the journal Nature, the 
Utah researchers suggest both the Martian and Utah rocks -- 
known as hematite concretions -- formed underground when 
minerals precipitated from flowing groundwater.

"We came up with the 'recipe' for blueberries," says Marjorie Chan, 
chair and professor of geology and geophysics at the University of 
Utah. "Before Opportunity landed, we thought there might be 
hematite concretions on Mars. That was based on our study of 
hematite-rich regions of southern Utah, where hematite balls are 
found in national parks and have long been a geological oddity that 
shows up in many rock shops."

The round rocks are found in southern Utah in Zion and Capitol 
Reef national parks, Grand Staircase-Escalante National 
Monument, Snow Canyon State Park and the Moab area.

Their diameters range from one-25th of an inch to 8 inches or more. 
They are known to New Agers as "moqui marbles." Some are the 
size of small blueberries like those on Mars.

Chan and her colleagues believe the Utah concretions formed 
perhaps 25 million years ago when minerals precipitated from 
groundwater flowing through much older Navajo sandstone, the 
spectacular red rock in southern Utah.

The National Aeronautics and Space Administration's Opportunity 
robot rover vehicle landed on Mars' Meridiani Planum on Jan. 25. 
Five days later, it detected hematite within gray pebbles dotting the 
landing site, and such pebbles later were spotted embedded in a 
rock outcrop. Cornell University scientist Steve Squyres, who heads 
the Opportunity science team, said Feb. 9 the small spheres look 
"like blueberries in a muffin" and might be concretions.

In their Nature paper, Chan and colleagues say the Martian 
"blueberries" may have formed in a similar manner to those in Utah, 
namely, when significant volumes of groundwater flowed through 
permeable rock, and chemical reactions triggered minerals to 
precipitate and start forming a layered, spherical ball.

"Given the similarities between the marbles in Utah and on Mars, 
additional scientific scrutiny of the Utah concretions and how they 
form will probably shed further light on the similar phenomenon on 
Mars," University of Washington scientist David Catling wrote in a 
Nature commentary accompanying the University of Utah study.

The concretions may bear on the search for evidence of past life on 
Mars because bacteria on Earth can make concretions form more 
quickly. Chan and colleagues plan to analyze whether there is 
evidence of past microbial activity in Utah concretions.

Chan conducted the new study with geology graduate student 
Brenda Beitler and emeritus professor of geology Bill Parry, both at 
the University of Utah; geologist Jens Ormo of the National Institute 
of Aerospace Technology in Madrid, Spain; and planetary scientist 
Goro Komatsu of the International Research School of Planetary 
Sciences at G. d'Annunzio University in Pescara, Italy.

Martian blueberries and marbles of the spirits

The Utah and Mars hematite concretions have similarities and 
differences.

In Utah and likely on Mars, "you have rocks that had iron in them 
originally," says Beitler. "Fluids travel through these rocks and leach 
out the iron. The water moves through cracks, holes, layers or 
pores until it reaches some place where the chemistry is different 
and causes the iron to precipitate out of the water as hematite."

A major difference is that the Martian "blueberries" probably are 
pure hematite -- a form of iron oxide that is gray because it has a 
larger crystal structure than the reddish form of iron oxide, 
commonly known as rust. The Utah concretions are mostly 
sandstone, cemented by hematite that makes up a few percent to 
perhaps one-third of the rock. The Martian concretions likely 
precipitated from acidic groundwater. Those in Utah precipitated 
when hydrocarbon-rich, briny fluids encountered oxygen-rich 
groundwater.

After the Utah concretions formed in groundwater, the surrounding 
Navajo sandstone slowly eroded away over millions of years, so the 
hard, erosion-resistant concretions accumulated on the ground, 
often in great numbers.

"The loose Utah concretions roll like marbles into depressions, 
forming 'puddles,' just like their Martian counterparts," Catling wrote. 
"The Hopi Indians have a legend that 'moqui,' or spirits of their 
ancestors, played games of marbles with the hematite concretions 
in the American southwest. Although anthropologists discourage 
use of the word 'moqui' to be respectful to Native Americans, New 
Age gem collectors sell concretions as 'moqui marbles' and claim 
that they are endowed with metaphysical powers."

Hematite, water and life

In 1998, the Mars Global Surveyor orbiting Mars detected what 
appeared to be a large area of hematite on Meridiani Planum. The 
broad plain was picked as Opportunity's landing site because 
scientists wanted to study the hematite, which almost always forms 
in water.

Scientists are interested in whether water once existed on Mars (or 
now exists beneath its surface) because water is necessary for life -
- and the possibility of life beyond Earth is one of the great 
questions long pondered by humanity.

"On Earth, whenever we find water, we find life -- in surface water 
or underground water, hot water or cold water -- any place there is 
water on Earth there are microbes, there is life," says study co-
author Bill Parry. "That's the bottom line: hematite is linked to life."

While other evidence from Opportunity suggests there once may 
have been standing water on Meridiani Planum, the Utah team's 
study strongly indicates the Martian "blueberries" probably formed 
in groundwater and not in surface water.

"The 'blueberries' easily could have formed in groundwater before 
there was standing water, if that did exist," Chan says.

Other scientists previously offered various explanations for 
Meridiani Planum's hematite, including that the mineral precipitated 
in large lakes or in hot springs when Mars' ancient volcanoes were 
active, or that hematite was left when water leached away other 
minerals, or that it formed when volcanic ash deposits were altered 
chemically.

Like Southern Utah, Like Mars

Chan says her team long suspected concretions like those in Utah 
might be found on Mars. The idea first was suggested by Ormo and 
Komatsu in a 2003 scientific abstract that got little if any attention. 
Ormo contacted Chan in spring 2003 and they started collaborating.

The researchers completed a much broader but yet-unpublished 
study last year indicating that several geological features were seen 
both in aerial photos of southern Utah's hematite-rich areas and in 
images of Mars' hematite regions taken by orbiting spacecraft. 
These features include large rocky landforms shaped like knobs, 
pipes and buttes, and places where bleached-looking rock forms 
white sediment beds or ring-shapes on the surface. Some of the 
pipes and other features are tens of yards long or wide.

The geologists determined the processes responsible for these 
large-scale features in Utah involved the flow of briny groundwater 
saturated with natural gas that bleaches sandstone, and that such 
groundwater flow, the precipitation of hard hematite-cemented rock 
and the later erosion of surrounding softer rock also would explain 
the formation of the erosion-resistant pipes, buttes, knobs and 
concretions. They concluded a similar process could have formed 
concretions and larger landforms on Mars.

Chan says studying concretions from Utah and Mars "will help us 
learn more about the history of Mars. When we have something to 
compare it to, it's a lot easier to figure out."

IMAGE CAPTIONS:

[Image 1:
http://www.utah.edu/unews/news_images_2004/jun/press2.jpg (1.5MB)]
University of Utah geologists say marble-shaped rocks known as 
concretions from Utah (left) formed millions of years ago in 
groundwater-soaked rocks, providing clues to the origin of similar 
concretions or so-called "blueberries" (right) discovered on Mars by 
NASA's Opportunity rover. The Utah concretions shown on the left 
range in diameter from one twenty-fifth of an inch to 2 inches, while 
the Martian versions on the right all measure less than one-fifth of 
an inch in diameter. (Scale of photos is different.)

Credit: Left image by Marjorie Chan and Brenda Beitler, University 
of Utah. Right image by NASA-Jet Propulsion Laboratory-Cornell 
University.

[Image 2:
http://www.utah.edu/unews/news_images_2004/jun/SF1.jpg (1.2MB)]
Marble-like rocks known as hematite concretions litter the surface 
of Navajo sandstone at Grand Staircase-Escalante National 
Monument in southern Utah.

The rocks accumulated after softer surrounding sandstone eroded 
away. They are similar to the so-called "blueberries" found on Mars 
by NASA's Opportunity rover.

Credit: Brenda Beitler, University of Utah.

[Image 3:
http://www.utah.edu/unews/news_images_2004/jun/SF2.jpg (889KB)]
Closeup of hematite concretions from Grand Staircase-Escalante 
National Monument in southern Utah. University of Utah geologists 
say the mostly round rocks formed millions of years ago 
underground in porous, water-soaked sandstone, and may provide 
clues to similar stones found on Mars by the Opportunity rover.

Credit: Brenda Beitler, University of Utah.