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Ring dikes

A ring dike is an intrusive igneous body. Their chemistry, petrology and field appearance precisely match those of dikes or sill, but their concentric or radial geometric distribution around a centre of volcanic activity indicates their subvolcanic origins.

Well known examples

Ossipee Mountains ring dike complex

Aerial photo

Geology

Alex MacPhail writes “…This is a recent geologic diagram of the Ossipee Ring (Dike) Complex from a paper written and presented by G. Nelson Eby, University of Massachusetts, Lowell, MA, and Ben Kennedy, McGill University, Montreal, QC, Canada. In their introduction they state that “Ossippee has played a central role in models dealing with the origin of ring dikes (Billings, 143, 1945; Chapman, 1976) and has long been considered a classic example of a ring-dike complex.”  They also state that the ring dike is part of the Younger White Mountain igneous province and between 130-100 million years old. In this province, in addition to the Ossipee Ring Complex, they write that “the largest intrusive complex is the White Mountain batholith which consists of multiple ring dikes intruded into by composite plutons.””

– http://whitemountainsojourn.blogspot.com/
– http://whitemountainsojourn.blogspot.com/2010/05/moat-mountain-moat-volcanics-look-at.html

 

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