Description:
The region under consideration (Figure 1) lies within the Cabullona Basin
of northeast Sonora. It is located south of the towns of Agua Prieta and
Naco. The region covers an area of approximately 1850 square kilometers.
The Agua Prieta region lies within the Basin and Range
Province of northeast Sonora. The rocks exposed in the area are predominantly
sedimentary rocks, although volcanic, plutonic, and metamorphic
rocks are locally abundant (Figure 2).
The Agua Prieta Area plays an important role in the paleotectonic interpretation
of SE Arizona and NE Sonora. In general, the structural evolution of
the region is poorly known and controversial. Pioneer field studies in the
Agua Prieta region by Taliaferro (1933), Imlay (1939), and King (1934); as
well as in adjacent areas by Ransome (1904) and Willson (1934) demonstrated
that this region displays several structural and stratigraphic features that
deserve more investigation. Recent studies by Rangin (1977) into late
Cretaceous - early Tertiary tectonics of the Northern part of Sonora (Figure 2)
suggested superimposed deformations and southwest directed thrusting in the
Cabullona Basin. Paleontologic studies by Gamper and Longoria (1980) have
shown that the Lower Cretaceous rocks of NE Sonora are predominantly open
marine deposits, locally rich in planktonic foraminifera. Nevertheless, much
remains to be learned about the tectonic evolution of the whole area.