California Institute of Technology

Guaymas Basin, Gulf of California, México

A recently identified mass-transport deposit stack in the Guaymas Basin, Gulf of California (México), and its implication in the basin tectonics 
  • Discovered a large stack of five mass transport deposits (MTDs) in the tectonically active Guaymas Basin using seismic profiles and core data.
  • MTDs originated from the Yaqui Delta and moved southwest, likely triggered by high sedimentation and tectonic activity.
  • The stack buried part of a transform fault, filled the southern graben, and contributed to the formation of a new northern seafloor graben.
  • Findings highlight how sediment loading and tectonics interact to reshape plate boundaries and submarine basins.
Collaborators: Joann Stock* (Caltech), Dan Lizarralde* (WHOI), Christian Berndt (GEOMAR), Antonio González-Fernández (CICESE), Carlos Mortera (UNAM), Kathleen Marsaglia (CSUN), Sam Hart (CSUN) Arturo Martin (CICESE), Christian Gallegos (CICESE)
Methods: Seismic reflection interpretation in Kingdom suite and sediment core analysis. 
Data Sets: Multichannel seismic data from Sonne 241 (GEOMAR) and Alpha Helix (CICESE), sediment core U1551A from IODP Exp.385.
 Published in Marine Geology DOI: 10.1016/j.margeo.2025.107592
*Advised by
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Tectonic setting of the Guaymas Basin. BC: Baja California; BCS: Baja California Sur; CTF: Carmen transform fault; GFT: Guaymas transform fault; GC: Gulf of California; YD: Yaqui Delta. The configuration of the fault system in the Gulf of California is from Lonsdale (1989). The yellow square bounds our study area in the GB and it corresponds to Figure 2 (right).
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Location map of our study area in the Guaymas Basin showing the various datasets used for this project. The Yaqui delta path is taken from Kluesner et al. (2014). CTF: Carmen transform fault; GTF: Guaymas transform fault; BCS: Baja California Sur; NG: Northern graben; SG= Southern graben. Bathymetric map was constructed using two data grids from UNAM and Ryan et al. (2009).
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NW-SE section of the Line 1 (Alpha Helix) and Line 108 (Sonne 241) showing the main characteristics of the MTD. Please see the line location shown in the bathymetric map.
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Conceptual model of the tectonic evolution of the Guaymas Basin before, during and after the emplacement of the MTD stack (MTD 3, 4, 5). The seismic data does not provide enough detail to determine the timing for MTD 1 and 2, so for this model is based on the crosscut relation observed in MTDs 3, 4, 5 observed in Line 1
Geochemical characterization and correlation of tephra intervals in Quaternary strata recovered during IODP Expedition 385 in the Guaymas Basin, Gulf of California
  • Recovered 4+ km of Quaternary sediments from 8 drill sites in the Guaymas Basin, an active seafloor-spreading rift.
  • Geochemical analyses revealed that thin tephra layers in the cores originated from Isla Tortuga, the basin’s only subaerial volcano.
  • Performed 2,100+ single glass shard analyses using electron microprobe and LA-ICP-MS.
  • Results shed light on tephra provenance, eruption timing, and support a regional tephrostratigraphy for the Guaymas Basin.
Collaborators: Priscilla Martinez (University of Arizona) Joann Stock* (Caltech), Kathleen Marsaglia* (CSUN), Brian Hausback (CSUS), and Arturo Martin (CICESE)
Methods: EPM and LA-ICPMS analyses.
Data Sets: Drilled cores acquired by the IODP EXP 385
Manuscript status: Manuscript in progress
​*Advised by
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Location map of our study area in the Guaymas Basin showing the locations of the sites drilled during the IODP expedition 385 that are used in this study. GFT: Guaymas Transform Fault; IT: Isla Tortuga.
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SiO2 vs Na2O+K2O (total alkali vs silicon plot in wt%
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Mid Ocean Ridge Basalt (MORB) normalized spider diagram from Sun and McDonough (1989)

Isla Tortuga, Gulf of California

Update in the Geology of Isla Tortuga Volcano: implications in the volcanic record of the Guaymas Basin, Gulf of California 
  • Isla Tortuga is a young volcanic island with two basaltic volcanic stages and pyroclastic deposits on its northeast side withouth a detailed geologic map.
  • A five-day field expedition collected samples for whole-rock geochemistry and Ar-Ar radiometric dating.
  • Significance of Isla Tortuga in the Guaymas Basin remains out of date.
  • Ongoing work aims to establish the eruption frequency and ages of Isla Tortuga volcano, as well as to produce a detailed geologic map.
Collaborators:  Joann Stock (Caltech), Brian Hausback (CSUS), Tobias Hofig (IODP), Arturo Martin (CICESE), and Rodey Batiza (University of Minnesota), and Emilia Pelegano-Titmuss (Hunter College)
Methods: Petrographic, XRF, electron microprobe, LA-ICPS, Ar-Ar analyses
Data Sets: Rocks collected in the field​
Manuscript status: In preparation

Comparative petrological and geochronological analysis of the Isla Tortuga volcano: gaining insights into a shared magmatic plumbing system in the Guaymas Basin, Gulf of California ​
  • IODP Expedition 385 drilled ~4 km of core in the Guaymas Basin, discovering sills with similar petrographic and geochemical traits as Isla Tortuga volcanic units.
  • Sills from Sites U1547 and U1548 were studied by Ge et al. (2023) (https://doi.org/10.1016/j.chemgeo.2023.121836); however, sills from sites U1545 and U1546 remain understudied.
  • Ongoing work aims to analyze the geochemical composition of sills at Sites U1545 and U1546, correlate the sills drilled during IODP Expedition 385 to Isla Tortuga, and develop a temporal–spatial model of the Guaymas Basin magmatic plumbing system.
Collaborators:  Joann Stock (Caltech), Brian Hausback (CSUS), Tobias Hofig (IODP), and Arturo Martin (CICESE)
Methods: Petrographic, XRF, LA-ICPS, easyMELTS modeling
Data Sets: Rocks collected in the field​ and samples recovered during IODP Exp. 385.
Manuscript status: Data analysis is ongoing
Check out my GSA Blog post!  (click here)
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Main crater of Isla Tortuga volcano
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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 non-polarized 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
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SiO2 vs Na2O+K2O (total alkali vs silicon plot in wt%)
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Primitive mantle-normalized multi-element diagram for trace elements
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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).

Central California and SE Nevada, USA

U-Pb xenocryst zircon (XZ) geochronology of two mafic intrusions in Southwestern Laurentia
  • Investigated unusually high zirconium concentrations in mafic magmas from Hanaupah Canyon, CA (>700 ppm) and Caliente, NV (100–200 ppm).
  • Dated U–Pb zircon ages at 193.5 ± 2.31 Ma (Hanaupah Canyon) and 28.9 ± 2.29 Ma (Caliente).
  • Identified xenocrystic zircons from multiple orogenic sources across the North American craton (Appalachian, Grenville, Rapakivi, Yavapai-Mazatzal, Mojave-Penokean).
  • Explored the tectonic context and implications for magma genesis and crustal recycling in the North American Cordillera.
Collaborators: Brian Wernicke* (Caltech), Carl Swindle (UCLA), and Claire Buchloz (Caltech)
Methods: Petrographic, SEM, XRF, U-Pb and K-Ar analyses
Manuscript status: In preparation
*Advised by
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Paleozoic and Mesozoic intrusive rocks outcrops from Western North America. H: Hanaupah Canyon, C: Caliente Basalt, EKM: East Klamath Mountains, NSN: Northern Sierra Nevada
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Zircon U-Pb geochronology from Hanaupah Canyon lamprophyre and Caliente diabase intrusions. (A-B) Watherill Concordia and (D) relative probability kernel density estimations (KDE) and related histogram from the Hanaupah Canyon lamprophyre. (D-E) Watherill Concordia and (F) relative probability KDE and related histogram from the Caliente diabase.

University of Sonora, México

New insights into the Northern Baja California Microplate reconstruction at ca. 12 Ma: Petrography, geochemistry, and paleomagnetism of the Ignimbrite of Hermosillo – Tuff of San Felipe in San Carlos, Sonora, México
  • Los Algodones (Guaymas, Sonora) exposes a Triassic–Late Cretaceous basement overlain by two tilted Miocene volcanic sequences.
  • The younger sequence includes the Los Algodones Ignimbrite (LAI), correlated with the widespread ca. 12 Ma Ignimbrite of Hermosillo – Tuff of San Felipe (IGH–TSF).
  • Geochemical and petrographic data link LAI to a similar unit in Cataviña, Baja California—430 km away—supporting a new tectonic reconstruction of the Baja California microplate.
  • Paleomagnetic results reveal significant tilting and vertical axis rotation, linked to transtensional deformation during Proto-Gulf of California rifting.​
Collaborators: Jesus Roberto Vidal Solano* (University of Sonora) and Joann Stock* (Caltech)
Methods: Petrographic, XRF, structural and paleomagnetic analyses
Manuscript status: Accepted in GSA Books
*Advised by
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Representative thin sections of the IGH-TSF from San Carlos, Sonora. A) Palagonitized facies; B) Tuffaceous facies; C) Welded facies. N= Natural light;. X= Polarized light; AF= Alkali feldspar; Cpx= Clinopyroxene; Ol= Olivine; Ox= Ti-Fe Oxides.
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Outcrop of palagonitized facies of IGH-TSF in contact with its lithic facies
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Spider diagram of normalization to MORB (Pearce, 1983) of the IGH-TSF deposits from San Carlos, Sonora, and some deposits from Cataviña, Baja California.