Cretaceous–Eocene magmatism and Laramide deformation in southwestern Mexico: No role for terrane accretion

Abstract

In southwestern Mexico, Late Cretaceous to Early Tertiary deformation has been generally associated with the Laramide orogeny of the Cordillera. Several alternative models consider the deformation to result from the accretion of the Guerrero terrane, formed by the Zihuatanejo, Arcelia, and Teloloapan intraoceanic island arcs, to the continental margin of the North American plate. Here, we present a detailed geologic and structural study and new 40 Ar/ 39 Ar and U-Pb ages for a broad region in the centraleastern part of the Guerrero terrane that allow the accretion model to be tested. In the Huetamo-Ciudad Altamirano part of the region, an almost complete Cretaceous-Paleogene succession records the transition from an early Cretaceous shallow-marine environment to continental conditions that began in Santonian times, followed by the development of a major continental Eocene magmatic arc. Folding of the marine and transitional successions signifi es a shortening episode between the late Cenomanian and the Santonian, and a subsequent, out-of-sequence, coaxial refolding event in Maastrichtian-Paleocene time amplifi ed the previous structures. A major left-lateral shear zone postdates the contractional deformation, and it passively controlled the geographic distribution of Eocene silicic volcanism. Minor transcurrent faulting followed.

U–Pb geochronological constraints on the Triassic–Jurassic Ayú Complex, southern Mexico: Derivation from the western margin of Pangea-A

“…These turbidites formed part of a submarine fan system (Ballena Formation: Centeno-García and Silva- Romo, 1997;Barboza-Gudiño et al, 2008, called the Potosí fan (CentenoGarcía, 2005), that was fed by an extensive river system (Alamar Formation: Barboza-Gudiño et al, 2010) and deposited along the western margin of Oaxaquia (Centeno-García, 2005. Distal parts of the Potosí fan are inferred to overlie oceanic crust and have been designated the Zihuatanejo terrane (Centeno-García, 2008;Martini and Ferrari, 2009). All of these rocks were deformed during east-vergent subduction of the Paleo-Pacific during the Early Jurassic, forming a wide accretionary prism of deformed turbidites and intercalated blocks of chert, limestone and pillow basalts (Zacatecas Formation, El Chilar Complex, Arteaga Complex, and Las Ollas Complex: Burckhardt and Scalia, 1906;Centeno-García and Silva-Romo, 1997;Talavera-Mendoza et al, 2007;Centeno-García, 2008;Dávila-Alcocer et al, 2009;Ortega-Flores et al, 2012).…”

Description of the Geology of the Tecolotlan Graben, Jalisco, Mexico

“…In the Tecolotlan graben, we fi nd that the model proposed by Martini et al (2009) and Martini and Ferrari (2011) better explains the chemical and mineralogical nature of the Cretaceous volcanic and sedimentary rocks. During the Late Cretaceous, the area was part of a shallow carbonate shelf as evidenced by deposition of the limestone of Los Guajes.…”

“…It has been proposed that the Guerrero terrane has an oceanic affi nity and collided with and accreted onto western Mexico during the Cretaceous (Campa and Ramirez, 1979;Campa and Coney, 1983;Centeno-García et al, 1993;Tardy et al, 1994;Freydier et al, 1997). However, Martini et al (2009), Ferrari (2011), andValencia et al (2013) concluded that the Guerrero terrane consists mostly of autochthonous or parautochthonous units on the rifted margin of the North American continent. Parts of the Cretaceous batholith have low to negative εNd values (2.4 to -1.7) and Precambrian Nd model ages also suggesting an older continental basement is present in the Jalisco block (Schaaf et al, 1995;Righter and Rosas-Elguera, 2001).…”

“…The simplest interpretation of the structural data is that the Cretaceous strata are folded. Folding, tilting, and thrusting, have been documented in the Cretaceous rocks of the Guerrero composite terrane elsewhere in southwestern Mexico (e.g., NietoSamaniego et al, 2006;Cerca et al, 2007;Martini et al, 2009;Martini and Ferrari, 2011). Martini et al (2010) indicate that the Albian age limestones of the Ixtapa Formation of southwestern Mexico have "experienced a moderate phase of shortening, which produced NW-SE-trending upright open folds," while the overlying Coniacian to Maastrichtian volcaniclastic rocks and continental sediments of the La Union Formation "display NW-SE-trending kilometric upright gentle folds."…”

The exhumed Eocene Sultepec-Goleta Volcanic Center of southern Mexico: record of partial collapse and ignimbritic volcanism fed by wide pyroclastic dike complexes

“…The ignimbrite flare-up of the north-central SMS took place from 38 to 31 Ma (De Cserna and Fries 1981;Morán-Zenteno et al 1999, 2004Alaniz-Álvarez et al 2002;Cerca et al 2007;González-Cervantes 2007;Martini et al 2009). It was the last episode of Paleogene magmatism in the region prior to the Miocene-Quaternary development of the Mexican Volcanic Belt (Ferrari et al 1999;Morán-Zenteno et al 1999) (Fig 1).…”