Structural pattern at the northwestern sector of the Tepic-Zacoalco rift and tectonic implications for the Jalisco block, western Mexico

Abstract

Analysis of the aeromagnetic anomalies over the northwestern sector of the Tepic-Zacoalco rift documents a NE-SW pattern of lineaments that are perpendicular to the inferred NW-SE boundary between the Jalisco block and the Sierra Madre Occidental. The boundary lies within the central sector of the Tepic-Zacoalco rift immediately north of the Ceboruco and Tepetiltic stratovolcanoes and extends up to the San Juan stratovolcano, where it intersects the NE-SW magnetic anomaly lineament that runs toward the Pacific coast (which intersects two volcanic centers). This N35• E lineament separates the central rift zone of low amplitude mainly negative anomalies (except those positive anomalies over the stratovolcanoes) from the zone to the north and west characterized by high amplitude positive long wavelength anomalies. The NE-SW lineament is parallel to the western sector of the Ameca graben and the offshore Bahia de Banderas graben and to the structural features of the Punta Mita peninsula at the Pacific coast, and thus seems to form part of a regional NE-SW pattern oblique to the proposed westward or northwestward motion of the Jalisco block. The orientation of this regional structural pattern at the northern end of the Tepic-Zacoalco rift seems consistent with proposed dominant SW-directed extension along the rift during the Pliocene and Quaternary, rather than with NW-SE lateral strike-slip faulting. The orthogonal pattern that characterizes the northernmost boundary of the Tepic-Zacoalco rift is oblique to the pattern observed in the Grande de Santiago river (which conforms the northern limit of the rift) and for the central-eastern sectors of the Ameca graben (south of the rift). This spatial arrangement of major lineaments and structural elements points to a complex tectonic history for the region that includes the rifting of the Gulf of California and margin deformation due to plate convergence and kinematic re-organization events, and which may have resulted in distinct episodes of left-lateral, right-lateral and normal faulting in Neogene times, as proposed in recent studies.

Overview of Recent Coastal Tectonic Deformation in the Mexican Subduction Zone

“…A submarine canyon has a half-graben structure where the associated Banderas fault extends westwards down to the MAT. Inland, the Banderas valley is identified as the extension of this active structure (ALVAREZ 2002(ALVAREZ , 2007FERRARI and ROSAS-ELGUERA, 2000;URRUTIA-FUCUGAUCHI and GONZALEZ-MORAN, 2006). The coastal landscape here is characterized by cliffs and rocky promontories alternating with beaches, a wide alluvial plain at Bahia de Banderas and a small number of lagoons with narrow barriers further south.…”

Microearthquakes in the Guadalajara Metropolitan Zone, Mexico: evidence from buried active faults in Tesistán Valley, Zapopan

“…In the study area, there is the possibility of having Basin and Range deformation oriented nearly N-S preferred trend (Henry and Aranda-Gómez, 1992;Aranda-Gómez et al 2000;Suter 2020b). The lateral component along the Tepic-Zacoalco rift has been subject to discussion since it could be toward the NW (e.g., Luhr et al 1985;Allan 1986;DeMets and Stein 1990;Carrillo-de la Cruz et al 2016) or the SW (Ferrari et al 1994;Urrutia-Fucugauchi 2006).…”

An inventory of phreatomagmatic volcanoes in the Trans-Mexican Volcanic Belt

“…Along the TMVB, monogenetic volcanic alignments have been associated with regional extensional stress regimes and their related fault systems (Demant, 1978;Suter et al, 2001;Urrutia-Fucugauchi and González-Morán, 2006;Sieron et al, 2021). In the Valle de Santiago area, the distribution of PVs does not follow the regional E-W to ENE-WSW trend as do the other neighboring volcanic structures.…”