Geology of La Reforma caldera complex, Baja California, Mexico

Abstract

A new geological map at 1:50,000 scale of La Reforma Caldera Complex has been produced applying modern survey methodologies to volcanic areas. This map aims to represent a reliable and objective tool to understand the geological evolution of the region. La Reforma Caldera Complex is a Pleistocene nested caldera located in the central part of the Baja California peninsula, Mexico. The twelve formations defined within the Quaternary volcanic record were grouped into three phases (pre-caldera, caldera, and post-caldera). The pre-caldera phase (>1.35 Ma) is characterized by scattered eruptions, mostly occurred in submarine environment. The caldera phase (1.35-0.96 Ma) groups several distinct explosive and effusive eruptions that formed the present-day caldera depression. The post caldera phase includes scattered effusive eruptions (ended at 0.28 Ma) and resurgence, characterized by several hundred meters of uplift of the central block within the caldera depression.

Strain partitioning in highly oblique rift settings: Inferences from the southwestern margin of the Gulf of California (Baja California Sur, México)

“…This volcanic complex overlies the Miocene Comondú deposits, which are in turn covered by a rift‐related volcanic suite (11 to 7.7 Ma; Conly et al, ), and marine and nonmarine deposits including the late Miocene Boléo Formation (Wilson & Rocha, ; Figure a). Cretaceous plutonic rocks in this area are only exposed in the bottom of canyons, such as the Arroyo de las Palmas (approximately 15 km northwest of Santa Rosalía; Wilson & Rocha, ), as well as within the La Reforma caldera depression (western margin of a main resurgent block; García Sánchez et al, ; Figure a).…”

“…(a) Simplified geological map of the Santa Rosalía‐Las Tres Vírgenes volcanic complex (location in Figure ; adapted mainly from Carta Geológico‐Minera, and García Sánchez et al, ). Stereoplot legend as in Figure .…”

Fauna de tiburones y rayas de la Formación Tirabuzón (Plioceno) en el Cañón El Álamo, sierras de La Reforma – El Aguajito, Baja California Sur, México

“…En la zona de estudio se han realizado algunos trabajos sobre la estratigrafía volcanosedimentaria y la geotermia (Garduño-Monroy et al, 1993, Verma et al, 2006, Viggiano-Guerra et al, 2009, Avellan et al, 2018García-Sánchez et al, 2019. Garduño-Monroy et al (1993) estudiaron la caldera El Aguajito, localizada al NW del cañón El Álamo, y en su trabajo mencionan que la caldera La Reforma y el complejo volcánico Tres Vírgenes se localizan en una depresión orientada NW-SE, que representa la prolongación NW de la cuenca de Santa Rosalía y que es controlada Figura 1.…”

Oceanographic heterogeneity influences an ecological radiation in elasmobranchs

“…All rights reserved (Murphy & Aguirre-Leon, 2002;Dolby et al, 2015). In spite of these key events between ~6 and Mya, the Colorado river delta established 4.5 Mya but continued to experience smaller fluctuation after that time (Dorsey, O'Connell, McDougall, & Homan, 2018); the Ballenas Channel formation was completed only ~2 Mya (Nagy & Stock, 2000); and recent volcanic activity and overriding plate uplifts changed dramatically the southwest coast of BCP ~2-1 Mya (Sutherland et al, 2012;Mark, Chew, & Gupta, 2017;García Sánchez et al, 2019). This combination of older and younger events was integral to the recent (i.e.…”

“…Hewitt, 2000) have resulted in opportunities for adaptive divergence and niche specialization (Rodrigues & Diniz-Filho, 2016). The establishment of the present-day heterogeneous environmental setting of the GC took place between ~2 and 1 Mya, after the final formation of the BCP and the main bathymetric features of the GC (Sutherland et al, 2012;Mark, Chew, & Gupta, 2017;García Sánchez et al, 2019). We hypothesize that these events, in combination with the mid-Pleistocene transition (1.2-0.8 Mya; Chalk et al, 2017), created ecological opportunities that likely promoted adaptive phenotypic differences between the lineages of Pseudobatos.…”