| This web page documents an agmatite at the margins of the Prata Pluton (point 31, 24M 0711824E 9138840N). Here, granitic magma. locally mingled brecciate migmatitic country rock. The migmatite was cold at the time of intrusion, and any anisotropy related to its layering played little or no role during intrusion of the 530Ma Prata magma. Only very locally there is evidence for some ductile deformation of the country rock, which we ascribe to a combination of break up and heating of the country rock. |
 Mingled diorite and granite intruding and brecciating cold country rock migmatite at the margin of the 530Ma Prata Pluton near the town of Monteiro in Paraiba State, Brazil. |
Three photographs depicting the increase in disaggregation of the country rock by the intruding magma
Figure 1a: Early stages of brecciation of country rock |
 Figure 1b. Intermediate stage of agmatite formation |
 Figure 1c. Extreme brecciation of country rock |
Typical features of brittle country rock disaggregation to form an angular intrusive migmatite known as agmatite
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Disaggregation accompanied by ductile deformation due to intensity of break-up and possibly heat.
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