Middle Tertiary plutonism in the Santa Catalina and Tortolita Mountains, Arizona

Geology of a zone of metamorphic core complexes in southeastern Arizona

“…A. Rehrig, 1977, oral commun. ) and discrepancies between K-Ar and Rb-Sr ages (Creasey and others, 1977;Shakel and others, 1977) are additional features shared by the complexes discussed here and those to the north (for example, Armstrong and Hansen, 1966;Compton and others, 1977;Hazzard and Turner, 1959;Lee and others, 1970;Kistlerand Willden, 1967;Simony and others, 1977;Thorman, 1965). However, the geologic relations and radiometric ages for the complexes described here appear for the most part to indicate younger ages and intrusion at shallower depths than is the case for the complexes to the north (Armstrong, 1976;Campbell and Reesor, 1977;others, 1976, 1977;Hazzard and Turner, 1959;Kistlerand Willden, 1967;Lee and others, 1970;Nielsen and Duncan, 1977;Reesor, 1970;Reesor and Moore, 1971;Simony and others, 1977; and others in this volume).…”

“…6). The complex has been the subject of a considerable amount of recent study (Drewes, 1974(Drewes, , 1976(Drewes, , 1977Creasey and Theodore, 1975;Davis and Frost, 1976;Banks, 1976Banks, , 1977Creasey and others, 1977;Shakel and others, 1977), many theses (principally at the University of Arizona), and a number of less recent studies (Moore and others, 1949;Bromfield, 1952;Dubois, 1959aDubois, , 1959bDamon and Giletti, 1961;Damon and others, 1963;Mayo, 1964;Catanzaro and Kulp, 1964;Livingston and others, 1967;Mauger and others, 1968;Shakel, 1972;Shakel and others, 1972; and several more local studies). Despite this effort, the number and ages of intrusions present and the number and ages of deformations involved are still undecided, probably in part due to divergence of opinion about the identity of some of the rock types, inconclusive results of the radiometric studies, and lack of complex-wide, detailed mapping and petrology.…”

“…7), occurs mostly as sill-like bodies along the northern margin of the complex (Figs. 6, 8), cuts Mesozoic deposits (Bromfield, 1952; Theodore, 1975), is locally foliated, and is intruded by both the gneiss of Windy Point and undeformed Tertiary intrusive rock (Moore and others, 1949;Peirce, 1958;Dubois, 1959aDubois, , 1959bCreasey and Theodore, 1975;Banks, 1976Banks, , 1977Creasey and others, 1977). The actual age of the quartz diorite has not been established; the published ages are Tertiary and essentially concordant with those of the intruding rocks (Table 3).…”

“…In the Santa Catalina-Rincon Mountains complex (Fig. 1), the Leatherwood Quartz Diorite of Bromfield (1952), which intrudes Mesozoic sedimentary rock (Creasey and Theodore, 1975) was involved in the metamorphism (Moore and others, 1949;Bromfield, 1952;Peirce, 1958;Dubois, 1959a;Creasey and others, 1977;Banks, 1976). In the Tortolita Mountains ( Fig.…”

“…However, the Rb-Sr ages show "poor systematics reflecting original differences or lack of isotopic equilibrium" (Shakel and others, 1977), and the U-Th-Pb ages, while reaffirming that a strong and widespread thermal event occurred in or lasted until the middle Tertiary, are not necessarily definitive of the age of the cataclasis or the age of emplacement of the major intrusive bodies involved. Additional petrographic and K-Ar data limit the nature of the thermal events, as host rocks near and even less than 1 km from the individual complexes are thermally unaffected by the presence of the complexes (Drewes, 1974(Drewes, , 1977Marvin and others, 1973;Banks, 1977;others, 1977, 1978;Creasey and others, 1977). K-Ar ages of unfoliated dikes and plutons cutting the cataclastic rocks indicate that the metamorphism ended no later than 20 m.y.…”