AGE AND OXIDATION STATE ESTIMATES FOR PLUTONS SPATIALLY ASSOCIATED WITH MINERAL DEPOSITS ALONG THE KETTLE DETACHMENT FAULT IN THE ORIENT QUADRANGLE, NORTHEASTERN WASHINGTON

As global demand for tungsten (W) rises, the U.S. relies on imports due to a shortage of deposits and limited domestic exploration. The oxidation state of magma, or oxygen fugacity (fO2), is crucial for ore formation. To constrain fO2, we use trace elements found in zircons, which preserve magmatic compositions at time of crystallization. We applied zircon geochronology and oxybarometry analyses using LASS-ICP-MS to eight plutonic samples from the Orient quadrangle in northeastern Washington. This region, cut by the Kettle Detachment fault, is known for its economic mineral occurrences and inactive mines, such as the Talisman mine, which has Cu and secondary W-deposits. Samples collected from the hanging wall include the Barstow granodiorite (OR1), a mafic intrusive near Kettle Falls (OR2), the Orient granite (OR5), an intermediate intrusive near Fifteen Mile Creek Pluton (OR7), a granite porphyry from the Fifteen Mile Creek Pluton (OR8), and the Deep Creek biotite quartz monzonite (OR9). The footwall samples consist of a pegmatite intruding through pre-Tertiary paragneiss and marble (OR12) and Kerry Creek quartz monzonite (OR17). Ti-in-zircon temperatures were calculated with an assumed TiO2 activity of 0.7. The hanging wall samples yielded the following average ages, temperatures, and ΔFMQ values: OR1: 103.8 ± 0.3 Ma, 767 °C, ΔFMQ +1.3; OR2: 51.3 ± 0.2 Ma, 742 °C, ΔFMQ +1.5; OR5: 51.5 ± 0.2 Ma, 766 °C, ΔFMQ +1.7; OR7: 51.3 ± 0.3 Ma, 804 °C, ΔFMQ +1.3; OR8: 51.2 ± 0.2 Ma, 815°C, ΔFMQ +0.9; OR9: 51.5 ± 0.2 Ma, 789 °C, ΔFMQ +1.2. The footwall samples yielded: OR12: 85.0 ± 0.3 Ma, 644 °C; and OR17: 51.8 ± 0.1 Ma, 750 °C, ΔFMQ +2.0. OR17, an Eocene pluton, located closest to the Talisman mine, yielded a higher ΔFMQ value compared to the Cretaceous plutons associated with W-deposits in the southern extent of the Kettle detachment fault, which exhibit low ΔFMQ values (< +0.5). The Orient quadrangle experienced major Eocene magmatism across > 370 km2 within only 0.6 ± 0.2 Myr in the Eocene due to regional extension caused by the accretion of Siletzia. By characterizing these plutons in the context of regional geologic mapping, we can further constrain the conditions necessary for regional ore formation.