Bathymetry and active geological structures in the Upper Gulf of California

Abstract

Bathymetric surveys made between 1994 and 1998 in the Upper Gulf of California revealed that the bottom relief is dominated by narrow, up to 50 km long, tidal ridges and intervening troughs. These sedimentary linear features are oriented NW-SE, and run across the shallow shelf to the edge of Wagner Basin. Shallow tidal ridges near the Colorado River mouth are proposed to be active, while segments in deeper water are considered as either moribund or in burial stage. Superposition of seismic swarm epicenters and a seismic reflection section on bathymetric features indicate that two major ridge-troughs structures may be related to tectonic activity in the region. Off the Sonora coast the alignment and gradient of the isobaths matches the extension of the Cerro Prieto Fault into the Gulf. A similar gradient can be seen over the west margin of the Wagner Basin, where in 1970 a seismic swarm took place (Thatcher and Brune, 1971) overlapping with a prominent ridge-trough structure in the middle of the Upper Gulf. It is believed that these major elongated features can be linked to active geological structures reflecting the geometry of the deep basement in the Wagner Basin.

High‐resolution migration history of the Subtropical High/Trade Wind system of the northeastern Pacific during the last ~55 years: Implications for glacial atmospheric reorganization

“…[] have shown that during the latest Holocene, northern Guaymas Basin received at least a portion of its terrigenous sediment flux via the Colorado River. In the Upper Gulf, slow spreading rates over the last ~5 Myr [ Lonsdale , ] have resulted in a gentle bathymetric gradient [ Lavin et al ., ; Alvarez et al ., ]: a ~100 m sea level drop effectively halves its area (Figure ), shifting the Colorado delta southward with the likelihood of significantly increasing terrigenous deposition in Guaymas Basin.An additional source of increased accumulation could be that, when sea level was actively lowering, downcutting brought in additional flux via sediment flushing from the Upper Gulf.…”

“…[7] Guaymas Basin sediment trap data [Thunell et al, 1993[Thunell et al, , 1994Sancetta, 1995;Thunell, 1998] reveal that organic carbon is suspended in the water column until July-August when it adheres to clay particles [Thunell, 1998] that originate from desert dust lofted during convective storms [Baba et al, 1991] and is deposited. Colorado River sediment is trapped in the Upper Gulf (on average less than 300 m deep; Figure 1) [Lavin et al, 1998;Alvarez et al, 2009], and very little modern terrigenous sediment reaches Guaymas Basin via this route. However, Dean et al [2004] have shown that during the latest Holocene, northern Guaymas Basin received a small proportion of its terrigenous sediment flux via the Colorado River.…”

In-Stream Energy by Tidal and Wind-Driven Currents: An Analysis for the Gulf of California

“…The southern transect changes drastically from very shallow to depths of several hundred meters, has a seafloor composed of sand and rocks [19], and the tidal range is mostly below 2 m (check the tidal charts produced by CICESE for the tidal gauges in the GIR, by consulting: http://predmar.cicese.mx/). In contrast, the northern transect is macrotidal and with water depths mostly below 50 m, with seafloor composed of cohesive and sandy sediments, and a tidal range that can reach around 6 to 7 m [20,21]. The difference in water depths and seabed sediment composition has important implications on the type of TEC that can be installed.…”

In-Stream Energy by Tidal and Wind-Driven Currents: An Analysis for the Gulf of California

“…The southern transect changes drastically from very shallow to depths of several hundred meters, has a seafloor composed of sand and rocks [14], and the tidal range is mostly below 2 m (check the tidal charts produced by CICESE for the tidal gauges in the GIR, by consulting: http://predmar.cicese.mx/). In contrast, the northern transect is macrotidal and with water depths mostly below 50 m, with seafloor composed of cohesive and sandy sediments, and a tidal range that can reach around 6 to 7 m [15,16]. The difference in water depths and seabed sediment composition has important implications on the type of TEC that can be installed.…”