Laramide to Miocene syn-extensional plutonism in the Puerta del Sol area, central Sonora, Mexico

Abstract

González-Becuar, E., Pérez-Segura, E., Vega-Granillo, R., Solari, L., González-León, C.M., Solé, J., López Martínez, M., 2017, Laramide to Miocene syn-extensional plutonism in the Puerta del Sol area, central Sonora, Mexico: Revista Mexicana de Ciencias Geológicas, v. 34, núm. 1, p. 45-61. ABSTRACTPlutonic rocks of the Puerta del Sol area, in central Sonora, represent the extension to the south of the El Jaralito batholith, and are part of the footwall of the Sierra Mazatán metamorphic core complex, whose low-angle detachment fault bounds the outcrops of plutonic rocks to the west. Plutons in the area record the magmatic evolution of the Laramide arc and the Oligo-Miocene syn-extensional plutonism in Sonora. The basement of the area is composed by the ca. 1.68 Ga El Palofierral orthogneiss that is part of the Caborca block. The Laramide plutons include the El Gato diorite (71.29 ± 0.45 Ma, U-Pb), the El Pajarito granite (67.9 ± 0.43 Ma, U-Pb), and the Puerta del Sol granodiorite (49.1 ± 0.46 Ma, U-Pb). The younger El Oquimonis granite (41.78 ± 0.32 Ma, U-Pb) is considered part of the scarce magmatism that in Sonora records a transition to the Sierra Madre Occidental magmatic event. The syn-extensional plutons are the El Garambullo gabbro (19.83 ± 0.18 Ma, U-Pb) and the Las Mayitas granodiorite (19.2 ± 1.2 Ma, K-Ar). A migmatitic event that affected the El Palofierral orthogneiss, El Gato diorite, and El Pajarito granite between ca. 68 and 59 Ma might be related to the emplacement of the El Pajarito granite. The plutons are metaluminous to slightly peraluminous, with the exception of El Oquimonis granite, which is a peraluminous twomica, garnet-bearing granite. They are mostly high-K calc-alkaline with nearly uniform chondrite-normalized REE and primitivemantle normalized multielemental patterns that are characteristic of continental margin arcs and resemble patterns reported for other Laramide granites of Sonora. The Laramide and syn-extensional plutons also have Sr, Nd and Pb isotopic ratios that plot within the fields reported for Laramide granites emplaced in the Caborca terrane in northwestern and central Sonora. Nevertheless, and despite their geochemical affinity to continental magmatic arcs, the El Garambullo gabbro and Las Mayitas granodiorite are syn-extensional plutons that were emplaced at ca. 20 Ma during development of the Sierra Mazatán metamorphic core complex. The 40 Ar/ 39 Ar and K-Ar ages obtained for the El Palofierral orthogneiss, the Puerta del Sol granodiorite, the El Oquimonis granite, and the El Garambullo gabbro range from 26.3 ± 0.6 to 17.4 ± 1.0 Ma and are considered cooling ages associated with the exhumation of the metamorphic core complex.Key words: Laramide magmatism; syn-extensional plutonism; geochronology; geochemistry; Sr-Nd-Pb isotopes; Sonora; Mexico. Gato (71.29 ± 0.45 Ma, el granito El Pajarito (67.9 ± 0.43 Ma, RESUMEN

The North American Cordilleran Anatectic Belt

“…The largest exposure is the Aconchi-El Jaralito batholith located between the Mazatán and Aconchi complexes, which contains the Huépac (58-55 Ma) and El Babizo leucogranites (71 Ma) among others (Roldán-Quintana, 1991;González-León et al, 2011). Late Cretaceous to Paleocene orthogneiss migmatite is reported from the Puerta del Sol complex and has been interpreted as the source for the El Pajarito ( 68Ma) garnet-bearing leucogranite (González-Becuar et al, 2017). The youngest leucogranite in the Puerta del Sol complex is the ~42 Ma El Oquimonis granite, a two-mica + garnet leucogranite (González-Becuar et al, 2017).…”

“…Late Cretaceous to Paleocene orthogneiss migmatite is reported from the Puerta del Sol complex and has been interpreted as the source for the El Pajarito ( 68Ma) garnet-bearing leucogranite (González-Becuar et al, 2017). The youngest leucogranite in the Puerta del Sol complex is the ~42 Ma El Oquimonis granite, a two-mica + garnet leucogranite (González-Becuar et al, 2017).…”

Heavy Metal Speciation, and the Evaluation and Remediation of Polluted Mine Wastes and Soils

“…The Mexican Geological Service [136] reported the geochemical composition of sediments with important metal(loid) concentrations [134]. Gonzales-Leon et al [137] described the geological formation of the Arizpe sub-basin, reporting high natural values of several elements in the soil, including those classified as toxic to humans, such as arsenic. In 2006, the Technological Institute of Sonora reported that concentrations of arsenic, cadmium, and thallium in Sonora River basin groundwater were found to be higher than those specified in the water quality criteria for drinking water by Mexican regulations and other international institutions, such as the Environmental Protection Agency of the USA and the World Health Organization.…”

Mapa geológico y base de datos geocronológicos de Sonora, México

“…En este trabajo se intenta reconocer a un tipo de plutones (Tic) leucocráticos, peraluminosos, generalmente de dos micas y con granate de ca. 60 a 32 Ma, que ocurren en áreas de complejos de núcleos metamórficos en el norte de Sonora (González-León et al, 2011;González-Becuar et al, 2017;González-León et al datos no publicados, incluidos en Tabla 1 del Material Suplementario).…”