Times are displayed in (UTC-05:00) Central Time (US & Canada)Change
282-3 Understanding Subduction Zone Rocks from Baja California, Mexico Using U-Pb Dating, QuiG, and ZiR
Session: Crustal Petrology, Part II
Presenting Author:
Sam Neumann
Authors:
Neumann, Sam1, Holder, Robert M.2, Connop, Charlotte3
(1) University of Michigan, Ann Arbor, MI, USA, (2) University of Michigan, Ann Arbor, Ann Arbor, MI, USA, (3) University of Michigan, Ann Arbor, MI, USA,
Abstract:
Cedros Island contains a Mesozoic-aged subduction mélange containing rock of varying metamorphic grades, within which high-pressure, low-temperature samples were collected. We present temperatures of metamorphism determined by zirconium-in-rutile thermometry (ZiR), pressures at which garnet in our samples reached, determined by quartz-in-garnet barometry (QuiG), and U-Pb dates of rutile and titanite using LA-ICP-MS to assess when the metamorphic conditions that formed these rocks occurred. The ZiR measurements found temperatures ranging from ~480 - ~630 °C, and the QuiG measurements resulted in pressures ranging from ~0.7 GPa to ~1.5 GPa. The U-Pb dates for titanite range from 140 ± 15 Ma to 165 ± 17 Ma, while the rutile U-Pb analysis resulted in one date at 154.7 ± 6.1 Ma. These results can help us better constrain our current models of subduction with actual temperatures and pressures of subduction rocks and provide a snapshot of the tectonic regime of North America’s western margin during the Mesozoic.
Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025