Volcanic and Igneous Plumbing Systems
Isla Tortuga is a young volcanic island in the Guaymas Basin formed during extensional tectonics in the Gulf of California. The island records two stages of basaltic volcanism, with older lava flows exposed in the south and younger units to the north, including a recent lava lake within the caldera and pyroclastic deposits along the northeastern flank. During a five-day field expedition, I collected samples for whole-rock major and trace element geochemistry and Ar–Ar radiometric dating to better constrain the timing and evolution of volcanism. In parallel, cores recovered during IODP Expedition 385 reveal sills intruding Quaternary sediments across the Guaymas Basin that share similar petrographic and geochemical characteristics with Isla Tortuga lavas. Ongoing comparative analyses aim to test whether these volcanic and intrusive units are linked by a common magma source. By integrating geochemical data with geochronology, this project seeks to develop a temporal and spatial model of the magmatic plumbing system in the Guaymas Basin.
View poster (Community Research Prioritization for Volcanoes Across the Alaska–Aleutian Arc, Caltech Library)
Read blog post (Speaking of Geoscience)
View poster (Community Research Prioritization for Volcanoes Across the Alaska–Aleutian Arc, Caltech Library)
Read blog post (Speaking of Geoscience)
Thin section of the youngest eruption in Isla Tortuga sampled from the lava lake in the central crater. The photomicrographs above were taken in plane light (left) and cross-polarized light (right). The white, long tabular crystals correspond to plagioclases, and red, yellow, and orange small crystals correspond to pyroxenes
MgO vs other major oxide elements (element oxide concentrations in wt.%) showing the correlation between IT samples and the sills analyzed by Ge et al. (2023).
Xenocrystic (XZ) and detrital (DZ) zircon age spectra as tracers of deep
crustal processes
Xenocrystic zircon (XZ) age spectra in mafic intrusions provide a rare window into deep crustal history. I analyzed zircons from two shallow mafic intrusions in eastern California and southern Nevada, which preserve Proterozoic and Mesozoic–Cenozoic ages consistent with emplacement. Unexpectedly, they also contain a significant population (20–25%) of early Paleozoic zircons (450–400 Ma), despite the lack of magmatism recorded at the surface during that time. I interpret this as evidence that mafic magmas can entrain zircons transported over distances greater than 100 km, revealing deep crustal processes not preserved in the geologic record. This work highlights the potential of XZ spectra, combined with bulk-rock Zr, to complement detrital zircon studies and uncover hidden magmatic histories.
Geological map of the Paleozoic and Mesozoic intrusive rocks in the North American Cordillera, after Burchfiel et al. (1992). Permian plutons are from Cecil et al. (2019) and Clemens-Knott and Gevedon (2023).
Zircon U-Pb age spectra from the Hanaupah Canyon lamprophyre and Caliente diabase. (A) Relative probability kernel density and estimations (KDE) and related histogram from Hanaupah Canyon lamprophyre, (B-C) Wetherill Concordia diagrams from the Hanaupah Canyon lamprophyre. (D) Relative probability KDE and related histogram from the Caliente diabase, (E-F) Wetherill Concordia diagrams from Caliente diabase.