Evidence for Young Lunar Volcanism
 
Oct 13, 2014:  NASA's Lunar Reconnaissance Orbiter (LRO) has provided
researchers strong evidence the moon's volcanic activity slowed gradually
instead of stopping abruptly a billion years ago. Scores of distinctive rock
deposits observed by LRO are estimated to be less than 100 million years old.
This time period corresponds to Earth's Cretaceous period, the heyday of
dinosaurs. Some areas may be less than 50 million years old.
 
"This finding is the kind of science that is literally going to make
geologists rewrite the textbooks about the moon," said John Keller, LRO
project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.
 
http://www.nasa.gov/sites/default/files/14-284_0.jpg
 
The feature called Maskelyne is one of many newly discovered young volcanic
deposits on the Moon. Called irregular mare patches, these areas are thought
to be remnants of small basaltic eruptions that occurred much later than the
commonly accepted end of lunar volcanism, 1 to 1.5 billion years ago. Image
Credit: NASA/GSFC/Arizona State University
 
The deposits are scattered across the moon's dark volcanic plains and are
characterized by a mixture of smooth, rounded, shallow mounds next to patches
of rough, blocky terrain. Because of this combination of textures, the
researchers refer to these unusual areas as "irregular mare patches."
 
The features are too small to be seen from Earth, averaging less than a third
of a mile (500 meters) across in their largest dimension. One of the largest,
a well-studied area called Ina, was imaged from lunar orbit by Apollo 15
astronauts.
 
Ina appeared to be a one-of-a-kind feature until researchers from Arizona
State University in Tempe and Westf„lische Wilhelms-Universit„t M�nster in
Germany spotted many similar regions in high-resolution images taken by the
two Narrow Angle Cameras that are part of the Lunar Reconnaissance Orbiter
Camera, or LROC. The team identified a total of 70 irregular mare patches on
the near side of the moon.
 
The large number of these features and their wide distribution strongly
suggest that late-stage volcanic activity was not an anomaly but an important
part of the moon's geologic history.
 
The numbers and sizes of the craters within these areas indicate the deposits
are relatively recent. Based on a technique that links such crater
measurements to the ages of Apollo and Luna samples, three of the irregular
mare patches are thought to be less than 100 million years old, and perhaps
less than 50 million years old in the case of Ina. The steep slopes leading
down from the smooth rock layers to the rough terrain are consistent with the
young age estimates.
 
http://tinyurl.com/mzx4gak
 
Click to visit the LRO home page
 
In contrast, the volcanic plains surrounding these distinctive regions are
attributed to volcanic activity that started about 3 1/2 billion years ago and
ended roughly 1 billion years ago. At that point, all volcanic activity on the
moon was thought to cease.
 
Several earlier studies suggested that Ina was quite young and might have
formed due to localized volcanic activity. However, in the absence of other
similar features, Ina was not considered an indication of widespread volcanism.
 
The findings have major implications for how warm the moon's interior is
thought to be.
 
"The existence and age of the irregular mare patches tell us that the lunar
mantle had to remain hot enough to provide magma for the small-volume
eruptions that created these unusual young features," said Sarah Braden, a
recent Arizona State University graduate and the lead author of the study.
 
The new information is hard to reconcile with what currently is thought about
the temperature of the interior of the moon.
 
"These young volcanic features are prime targets for future exploration, both
robotic and human," said Mark Robinson, LROC principal investigator at Arizona
State University.
 
Details of the study are published online in the Oct. 12th edition of Nature
Geoscience.
 
Credits:
Production editor: Dr. Tony Phillips | Credit: Science@NASA
 
More information:
 
LRO is managed by Goddard for NASA's Science Mission Directorate at NASA
Headquarters in Washington. LROC, a system of three cameras, was designed and
built by Malin Space Science Systems and is operated by Arizona State
University.
 
To access the complete collection of LROC images, visit http://l
oc.sese.asu.edu/
 
 
Regards,
 
Roger

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 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)