Details

Autor(en) / Beteiligte

• Higa, Justin T.
• Brown, Nathan D.
• Moon, Seulgi
• Stock, Joann M.
• Sabbeth, Leah
• Bennett, Scott E. K.
• Martín‐Barajas, Arturo
• Argueta, Marina O.

Titel

Microcontinent Breakup and Links to Possible Plate Boundary Reorganization in the Northern Gulf of California, México

Ist Teil von

• Tectonics (Washington, D.C.), 2022-01, Vol.41 (1), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2022

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Faults on microcontinents record the dynamic evolution of plate boundaries. However, most microcontinents are submarine and difficult to study. Here, we show that the southern part of the Isla Ángel de la Guarda (IAG) microcontinent, in the northern Gulf of California rift, is densely faulted by a late Quaternary‐active normal fault zone. To characterize the onshore kinematics of this Almeja fault zone, we integrated remote fault mapping using high‐resolution satellite‐ and drone‐based topography with neotectonic field‐mapping. We produced 13 luminescence ages from sediment deposits offset or impounded by faults to constrain the timing of fault offsets. We found that north‐striking normal faults in the Almeja fault zone continue offshore to the south and likely into the nascent North Salsipuedes basin southwest of IAG. Late Pleistocene and Holocene luminescence ages indicate that the most recent onshore fault activity occurred in the last ∼50 kyr. These observations suggest that the North Salsipuedes basin is kinematically linked with and continues onshore as the active Almeja fault zone. We suggest that fragmentation of the evolving IAG microcontinent may not yet be complete and that the Pacific‐North America plate boundary is either not fully localized onto the Ballenas transform fault and Lower Delfin pull‐apart basin or is in the initial stage of a plate boundary reorganization. Plain Language Summary Earth's rocky outer layer is broken into several tectonic plates. These plates move against each other at plate boundaries, causing geologic hazards like earthquakes. The locations of plate boundaries also move through time by a process called plate boundary reorganization. Here, we examine Isla Ángel de la Guarda (IAG), an uninhabited island in the northern Gulf of California, to study a potential plate boundary reorganization between the Pacific and North America plates. We looked at the pattern and activity of faults on southern IAG to assess their connection to the current plate boundary. We found that the faults have a similar orientation to an active, offshore part of the plate boundary southwest of IAG and that onshore faults are also active because they cut layers of sand and gravel that were deposited less than 50,000 years ago. Active faults that align with the plate boundary may imply that both are presently linked. A possible result of this linkage is the reorganization of the Pacific‐North America plate boundary across IAG. Key Points On Isla Ángel de la Guarda, we map the normal, north‐striking, Almeja fault zone that projects into an active offshore basin Luminescence ages from faulted terraces indicate late Quaternary fault activity Similar orientation and extension direction suggest a kinematic linkage between the Almeja fault zone and the active offshore basin