60-48 Preliminary Petrographic and Geochemical Analysis of Cu-Mo-Bearing Granodiorite Porphyry from the Bagdad Mine, Arizona

Session: 2YC and 4YCU Geoscience Student Research Poster Showcase

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Abstract:

The Bagdad mining district in west-central Arizona contains significant copper deposits in both sulfide and oxide mineralization, mainly associated with Laramide-age (60-70Ma) granodiorite porphyry intrusions. The primary sulfide minerals are chalcopyrite and bornite, with secondary Cu minerals of chalcocite, molybdenite, chrysocolla, malachite, and azurite. The ore deposit, hosted within a quartz monzonite stock, is located at the intersection of NE and NW shear zones, which likely controlled the emplacement of the quartz monzonite stock and subsequent mineralization. This study analyzes samples collected in 2014 from recently exposed Cu-rich veins at the active Freeport-McMoRan Bagdad Mine by Dr. Keith Brunstad (SUNY Oneonta). The investigation aims to identify any rare minerals and assess ore grade by determining the volume percent of ore minerals in each sample. Preliminary analysis of polished thick sections confirms chalcopyrite and bornite as primary phases, with molybdenite present as a secondary phase. Thick sections analyzed under reflected light using an Olympus BX51 microscope revealed preliminary volume estimates of 18% quartz, 19% k-feldspar, 18% biotite, and 45% chalcopyrite. Further evaluation will concentrate on using the SEM-EDX (Hitachi 3030 SEM and Bruker EDX) at SUNY Oneonta to confirm these identifications and detect rare trace minerals. The findings from this study provide insight into the mineralogical composition of the Cu-rich veins and contributes to evaluating the economic viability of the Bagdad deposit and similar deposits like it.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10356

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