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A Newly Identified Mass-Transport Deposit in the Guaymas Basin, Gulf of California: Implications for Regional Tectonics and Continental Slope Stability

We report a significant mass transport deposit (MTD) in the southeastern Guaymas Basin, central Gulf of California, Mexico, which is a young marginal rift basin characterized by active seafloor spreading. We interpret 16 high-resolution seismic reflection profiles across the E-SE basin margin. Within these data we identify an ~85-m-thick, wedge-shaped unit with a dominantly transparent seismic reflection character, though containing some small packages of laterally discontinuous reflectors, and a bumpy upper surface. We interpret this unit to be a MTD that originated from the Yaqui Delta region of the Sonoran margin and infer that a combination of high sedimentation rate and active tectonics contributed to the MTD event. The presence of buried ‘flower structures’ within the data indicates that the MTD buried part of the transform fault separating Guaymas Basin and the continental Sonoran margin. The MTD appears to have occurred near the transform/spreading-center intersection. That intersection and the axial graben, the surface expression of extension, have since jumped northwestward, apparently in response to the MTD emplacement, creating a second, northern seafloor graben, where previously there had only been one in Guaymas Basin. The MTD extends to the NE margin of the northern graben, thins to the SE of the basin, partially fills the southern graben, and has been faulted and overlain by younger sediments since emplacement. These inferences are based on a geological and structural interpretation of ~708 km of high-resolution multichannel seismic reflection data. We estimate the area and volume of the observed MTD to be 3346 km² and 303.3 km³, respectively. Our results contribute to the understanding of the tectonic evolution of the Guaymas Basin and provide new insights into the interaction between continental slope failure at active continental margins, spreading-center tectonics, and high flux of sediment transport into this young spreading system in the Central Gulf of California.

Session: Seismology in the Oceans: Pacific Hemisphere and Beyond - I

Type: Oral

Room: Tubughnenq’ 3

Date: 5/2/2024

Presentation Time: 08:15 AM (local time)

Presenting Author: Adriana Piña

Student Presenter: Yes

Additional Authors