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   
      
   --- D'Bridge 3.99   
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