Edades K/Ar de 54 rocas ígneas y metamórficas del occidente, centro y sur de México

fifty-four samples of igneous and metamorphic rocks from south, central and northern mexico have been analyzed by the k/ar method. samples were provided to instituto de geología of universidad nacional autónoma de méxico by the consejo de recursos minerales (now servicio geológico mexicano) from selected regions of the following states: baja california sur, colima, durango, estado de méxico, guerrero, jalisco, oaxaca, san luis potosí, sinaloa y zacatecas. all relevant information for each sample, including location, geological unit, petrographical description, mineral analyzed and age is described in the text; analytical data for each sample are given as a table. ages range from 2 ma to 249 ma, with about 30% being oligocene ages related to volcanism and plutonism in the sierra madre occidental and sierra madre del sur.