434 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



Jt'lS 



Fig. 27.8. Thrust plates of the Cochise 

 Head and Vanar quadrangles, Chiricahua 

 Mountains. Reproduced from Sabins, 1957. 

 Compare with Fig. 27.5. 



Of particular importance in regional tectonics are the ages of the 

 Chico Shunie quartz monzonite and the Cornelia quartz monzonite. The 

 Chioo Shunie precedes the Concentrator volcanics and the Cornelia 

 follows. The sequence is similar to the one in the Dragoon and Mule 



Mountains of southeastern Arizona, except for the absence of the Bisbee 

 sediments, which may be represented in part by the Concentrator vol- 

 canics. Gilluly assigns the Chico Shunie intrusion questionably to the 

 Mesozoic and the Cornelia intrusion to the early Teritary. Speculatively, 



