Wrinkled? Yes, but how old?

A wrinkle ridge formation in eastern Mare Frigoris (54.430°N, 35.670°E), from a 2 km -wide field of view from LROC Narrow Angle Camera (NAC) observation M139672711R, spacecraft orbit 5717, September 21, 2010; 56.22° incidence angle, resolution 47 cm per pixel from 38.87 km. LROC Featured Image, "Wrinkled, yes, but how old? - Released January 21, 2014 [NASA/GSFC/Arizona State University].

H. Meyer
LROC News System

Wrinkle ridges are not only some of the most striking features that wind their way across the lunar mare, but they are also extremely informative. Wrinkle ridges are the surface expression of tectonic stresses, and from observing the morphology of the ridges, we can interpret the tectonic history of the regions in which they are found.

Mare Frigoris hosts intricate systems of intertwining wrinkle ridges, suggesting a complex history. It is thought that this area was a topographic low that was later filled in with dense mare, causing the less dense anorthosite crust to sag as it underwent isostatic adjustment. The sagging resulted in compression at the surface, and the development of wrinkle ridges. As the crust was compressed it fractured, and long linear stretches of crust were pushed on top of itself thus forming these fascinating ridges.

LROC WAC context image of eastern Mare Frigoris. The full NAC field of view is outlined in red and that of the LROC Featured Image released January 21, 2014 is boxed in yellow [NASA/GSFC/Arizona State University].

The ropy appearance of the ridges in the WAC context image above are a testament to the complex motion that took place within the rock, indicating multiple directions of stress. Though most of the tectonic activity that produced wrinkle ridges in Mare Frigoris is thought to have occurred ~2.6-3.8 billion years ago, recent work suggests that wrinkle ridges may have formed in this region only 1.2 billion years ago. Believe it or not, that is young (for the Moon at least)!

Who knew wrinkles could be useful? Explore the Moon's wrinkles for yourself, HERE. 

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