The Triassic/Jurassic boundary and the Jurassic stratigraphy and biostratigraphy of northern Sonora, northwest Mexico

Abstract

RESUMEN

Ammonoid biostratigraphy and paleobiogeography of Lower Jurassic sections from Sonora (northwest Mexico) and their tectonic implications

“…Stone and Stevens (1988) considered Caborca as a basement block reaching its position by a late Paleozoic displacement, whereas Anderson and Silver (2005) and Anderson (2015) suggest a Late Jurassic movement along the trace of the Mojave-Sonora megashear. Despite their differences, most variants of the different models assume that the kinematics of the suspected movement was transverse and sinistral (Dickinson and Lawton, 2001;Anderson and Silver, 2005;Anderson and Nourse, 2005; et al, 2008;Amato et al, 2009;Colpron and Nelson, 2009;Anderson 2015;Riggs et al, 2016;Lawton et al, 2017;González-León et al, 2017). Contrary to the previous studies, the movement itself was questioned by Poole et al (2005), who suggest that the Caborca block is an "autochthonous promontory of southwest Laurentia".…”

“…It includes our study area in northern Sonora, other areas with major Jurassic ammonoid fossil localities in the southwestern US and farther afield in British Columbia, with which paleogeographic links will be assessed. The geological setting, including the tectonic evolution and stratigraphy of the study area, is outlined here based on a recent summary (González-León et al, 2017).…”

“…In accordance with the interpreted fore-arc tectonic setting of the El Antimonio basin (Stanley and González-León, 1995;González-León, 1997;González-León et al, 2005), much of the Lower Jurassic Sierra de Santa Rosa Formation was deposited in deep-water environments and records an increased rate of sedimentation following the initiation of Jurassic arc magmatism at ca. 200 Ma (González-León et al, 2017).…”

Jurassic Intrusives of the Coyote Mountains, Western Salton Trough, Southern California and Their Relationship to the Nazas Arc of Northern Mexico

“…Figure modifiedfromGonzález-León et al (2017). González-León et al's data shows the second (Jurassic) episode of magmatic activity of the Nazas Arc, which is inferred from detrital zircons of the Jurassic Sierra de Santa Rosa, Basomari, Lilt Formations (original data fromGonzález-León et al, 2009) combined with detrital zircons from the Cucurpe Formation (data fromMauel et al, 2011).…”