Arizona MCC
The particular interest of this website will be the MCCs present in the
state of Arizona. The figure below (Reynolds, et al., 1980) details the
placement of the MCCs. The general trend is NW and parallel to the edge
of the Colorado Plateau and the Transition Zone.
Timing: Arizona
The Cenozoic dates assigned to the Arizona Core Complexes
post-date the two major deformation events of the western US, namely the
Sevier (~140 Ma - 60 Ma) and Laramide (~80 Ma - 40 Ma) Orogenies. Yet pre-date
the Southern Basin and Range extension and rifting events (~25 Ma) (Coney,
1980, dates are Jones, lecture notes).
See
Arizona Geologic History. Their formation began 10 - 30 My before
the Pacific and North American Plates made contact and formed the San Andreas
Fault and subsequent back arcs and Basin and Range extension (Coney and
Harms, 1984).
To summarize:
Catalina Complex
The Santa Catalina-Ricon Mountains are in southeastern Arizona just outside
of Tucson, Arizona. This complex has been fairly heavily studied and is
considered to be a typical Southern Basin and Range MCC. Mid-Tertiary extension
lifted the rocks (Dickinson, 1991) from a depth of about mid crust to 1.5
km above the valley floor. 
(Figure
Davis, 1987)
A progression in the transformation of the rocks of the complex can
be seen by the progression of deformed rocks: Mylonites and ultramylonites
were "derived from the Precambrian and Tertiary quartz monzonites; chloritically
altered microbreccias derived
from the mylonite and ultramylonite;
fine-grained microbreccias (cataclasite
and ultracataclasite) derived
from the chloritically altered breccias; the detachment fault (or decollement)
separating cataclastic and mylonitic rocks below from nonmylonitic, noncataclastic
and mylonitic rocks below from nonmylonitic, noncataclastic cover rocks
above; and some folded Paleozoic cover rocks." (Davis, 1986)
The detachment fault is considered to be a low angle normal fault. The
uplifted areas have also been deformed by the Basin and Range extension
in the region after the main development of the core complex (Myers, 1994).