ABSTRACT The Santa Catalina and Rincon Mountains north and east of Tucson, Arizona, form one of the largest core complexes on Earth. Both ranges consist primarily of Eocene leucogranites that intrude Proterozoic and late Cretaceous granitoids, and two Oligocene plutons. Mylonitic fabrics are well developed on the southern flank of the Santa Catalina Mountains and the southwestern flank of the Rincon Mountains. The corrugated form of the two ranges reflects the grooved form of the ca. 15–30 Ma Catalina–San Pedro detachment fault exposed primarily at the foot of the ranges. Normal displacement on two younger high-angle normal faults is responsible for much of the substantial relief of the ranges. This field guide is focused on fault rocks and mylonitic fabrics in the footwalls of the detachment fault and the high-angle Pirate normal fault, and includes description and analysis of shear-zone kinematics and processes, U-Pb geochronology of leucogranites, and core-complex geomorphology.

Abstract The development of more predictive models for the distribution patterns of large ore deposits and districts is critical for future discovery success in mineral exploration. Some studies have suggested that the distribution of orogenic Au and porphyry Cu deposits appears ordered with a periodic spacing in some mineral provinces, but it remains unclear if spatial periodicity is a common feature of diverse mineral systems. We present evidence for spatial periodicity of large mineral deposit clusters along 20 major structural corridors from nine world-class mineral provinces with five ore deposit types (orogenic Au, porphyry Cu, sediment-hosted Cu and Zn-Pb-Ag, and diamondiferous kimberlites). For orogenic Au deposit clusters, spatial periodicity commonly occurs around 30 to 40 km (range 19–50 km) in the Eastern Goldfields (Australia), Abitibi (Canada), and Sierra Foothills (United States) provinces. Periodicity of moderate- to giant-sized sediment-hosted Cu deposit clusters occurs around 27 km in the Central African Copperbelt (Zambia, Democratic Republic of Congo). Large porphyry Cu deposit clusters show periodicity around 65 to 122 km in the American Cordillera (United States, Mexico, Chile). Large shale-hosted Zn-Pb-Ag deposit clusters have a periodicity around 116 km in the Carpentaria province (Australia). Finally, kimberlite clusters have a spatial periodicity around 121 to 237 km in southern and central Africa. We also observed a dual periodicity along some structural corridors, with smaller deposits located at half the spacing of giant deposits. Whereas the mineral provinces studied were selected on the basis that they seemed to show spatial periodicity, many other provinces worldwide do not appear to display spatial periodicity of ore deposits. We link our results to the phenomenon of self-organization, which explains emergence of large-scale spatial (and temporal) order in complex systems as an effective mechanism to dissipate large energy gradients. As the best examples of spatial periodicity of ore deposits identified to date are associated with some of the world’s best endowed mineral provinces, it is possible that overall province endowment is linked to both the degree of self-organization and the magnitude of regional energy gradients. Further research is required to identify relevant underlying geologic causes for spatial periodicity. Nevertheless, we provide two case studies suggesting that the intersection of preexisting basement fault sets with at least semiregular spacing may be a common control on spatial periodicity of mineral deposits. Where spatial periodicity of mineral deposits is observed to occur, it can improve the predictive capacity of exploration models and ore discovery rates.

The Pinacate volcanic field is ~330 km SSW of Phoenix, and it is a popular destination for volcanology and planetary geology field trips. The volcanic field, located on the Pinacate Biosphere Reserve in Sonora, Mexico, is a 1500 km 2 basaltic field including a shield volcano, lava tubes, maars, a tuff cone, cinder cones, pāhoehoe and ‘a‘ā lava flows as young as 12 ka, and phreatomagmatic constructs as young as 32 ka. We developed an image-based set of exercises for a 2 day field trip focusing on (1) Crater Elegante, a maar crater, (2) pāhoehoe and ‘a‘ā flows near Tecolote Cone campground, (3) the complex eruptive history of Mayo (cinder) Cone, and (4) Cerro Colorado tuff cone. This paper discusses exercises to teach concepts in visible and radar image interpretation and planetary volcanology, and provides an overview of the field trip.