Elongated Magma Plumbing System Beneath the Coso Volcanic Field, California, Constrained by Seismic Reflection Tomography

Abstract

The Coso volcanic field (CVF) is situated in a tectonically complex region in southern California, bounded by the Basin and Range in the east, the Sierra Nevada block in the west, the Owens Valley in the north, and the Garlock Fault in the south (Figure 1). The CVF is well-known for its compositionally bimodal Pleistocene magmatism, represented by the coexistence of high-silica rhyolite and basalts erupted at a constant rate during the past ∼0.5 Ma (e.g., Bacon, 1982;Manley & Bacon, 2000). The evolution of the CVF is closely related to a releasing bend between the Airport Lake Fault and the Owens Valley Fault, which was developed following the earlier extensional regime introduced by the westward propagating Basin and Range extension (e.g., Duffield et al., 1980;McQuarrie & Oskin, 2010;Monastero et al., 2005). The present-day transtensional deformation results in widely distributed crustal shearing and strike-slip faulting of the brittle upper crust, leading to intensive earthquake activities in this region (Monastero et al., 2005).Geochemical and thermobarometric studies indicate the existence of a long-lasting magma reservoir beneath the CVF in the upper to middle crust, which directly feeds the Pleistocene volcanic activities and supplies the

Multi‐Scale Seismic Imaging of the Ridgecrest, CA, Region With Waveform Inversion of Regional and Dense Array Data

“…This feature is largely inherited from the initial model and is in consistent with the P‐ and S‐wave travel time tomography results of Q. Zhang and Lin (2014) and D. Wang et al. (2022) that identified low‐velocity anomalies in the middle crust, suggesting the presence of magma chambers below the Coso volcanic field. Additionally, large‐scale tomography results revealed a notable low‐velocity zone in the uppermost mantle within a depth range of 60–90 km, which may indicate a deeper mantle magma source that feeds the shallower crustal chambers (Jiang et al., 2018).…”

Comparing Adjoint Waveform Tomography Models of California Using Different Starting Models

“…Low velocities south of the Sierra Nevada mountains likely correspond to the Coso volcanic field (Box 7, Figure 3f). Near the border with Mexico, the low velocities in all three models correspond to the Salton Sea region (Box 8, Figure 3e); these low velocities are bounded by the San Andreas Fault system, an observation that has also been seen by other workers (e.g., Ajala et al., 2019; D. Wang et al., 2022).…”

CANVAS: An Adjoint Waveform Tomography Model of California and Nevada

“…We chose three stations in Northern California to compare observed and synthetic waveforms. The path between the event and stations sample a variety of tectonic regions, including the low velocities of the Salton Sea (e.g., Ajala et al., 2019; Wang et al., 2022) and the Central Valley (e.g., Barak et al., 2015). Station TA.N02D, a temporary USArray station (https://www.usarray.org/) over 1,200 km from the source, passes through the Sierra Nevada mountains, which is a high‐velocity region.…”

“…Iterating the model at shorter periods would help to better constrain the Los Angeles Basin. Finally, the Salton Sea appears as a low velocity anomaly in V S above 10 km depth (Section D‐D’ in Figure 10; Share et al., 2021; Wang et al., 2022); this region is associated with thin crust, high heat flows, and Holocene volcanic activity (e.g., Ajala et al., 2019; Wright et al., 2015).…”

“…Over the past 30 years, many seismic tomography models of California, whether of the whole state or of a sub‐region of it, have been proposed (e.g., Chen et al., 2007; Lin et al., 2010; Pollitz, 1999; Shaw et al., 2015; Stanciu & Humphreys, 2021; Suess & Shaw, 2003; Tape et al., 2009; Tape et al., 2010; Thurber et al., 2009; Wang et al., 2021; Wang et al., 2022). Models that include the whole state (Lin et al., 2010; Stanciu & Humphreys, 2021) were derived using ambient noise tomography (Lin et al., 2010) and travel‐time tomography (Stanciu & Humphreys, 2021).…”