12 Guaymas Basin and Gulf of California Subsurface Systems and Energy Applications

This session will present subsurface research in the Gulf of California, especially IODP Expedition 385 to Guaymas Basin that explored the linkages between tectonics, magmatism, sedimentation, hydrothermalism, carbon cycling, and microbial life. Merged sessions: Subsurface Research  in Guaymas Basin and the Gulf of California and Energy Resources and Economic Development in Baja California: Fossil, Renewable, and Transition Minerals.

Wednesday, 22 April 2026
1:30 PM - 5:30 PM
LMH, Isla Carmen

Guaymas Basin seafloor surveys by Submersible and ROV

Paper number: 12-1
Program: Technical Sessions
Time: 1:35 PM – 1:50 PM

Authors

Abstract

Guaymas Basin has experienced a busy decade of seafloor visits, exploration, mapping and visual recordings, much of this in preparation of IODP Expedition 385 but also in its own right, to observe the numerous manifestations of hydrothermalism and cold seepage that are packed into a relatively small area. Here we provide an annotated tour of Guaymas Basin seafloor landscapes, and vent and cold seep fauna using photos and footage from two RV Atlantis & HOV Alvin Expeditions (AT37-06 and AT42-05) in December 2016 and November 2018, and from EV Nautilus and ROV Hercules in October 2017. Highlights include the first submersible visit to Ringvent, an extensive off-axis active hydrothermal system driven by recent sill emplacement, and the first submersible visit to the Central seep area with carbonate mounds, surficial methane hydrates, and cold seep fauna a few miles from the northern Guaymas axial valley (both 2016). The 2017 expedition recorded cold seep fauna and active seepage on the edge of the Sonora Margin and in the southeastern Guaymas Basin, and extensive footage from a recently discovered, highly active hydrothermal vent massif at the northern axial valley. Here, the ROV follows a geochemical and faunal gradient from rust-colored talus slopes populated with crabs and octopus, towards sulfide-dependent chemosynthetic Riftia colonies on active chimneys, and finally hot, friable and recently precipitated flanges and chimneys emitting hydrothermal plumes. Close-ups from the southern Guaymas Basin hydrothermal area (2016 and 2018) document visually outstanding sulfide-oxidizing microbial mats, including some of the largest bacterial filaments on Earth, and invertebrate fauna and microbiota associated with petroleum seepage through seafloor mineral concretions that represent hot spots of fossil carbon-fueled benthic life. Invisible for cameras but within reach for modern microbial surveys using metagenomic techniques, the diversity of energy-rich redox couples and carbon sources at the Guaymas seafloor fuels exceptionally rich microbial life, much of it relevant for reconstructing the tree of life. To summarize, nowhere else on Earth is it possible to observe a geobiological seafloor landscape of comparable dynamics and diversity, where active hydrothermalism, cold methane seepage and natural petroleum discharge coexist within tens of miles and sustain their sometimes distinct, sometimes overlapping benthic ecosystems. The entire basin should be protected for the future.

Geological Society of America Abstracts with Programs. Vol. 58, No. 3

doi: 10.1130/abs/2026CD-410757

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