Evolution of a large Quaternary monogenetic field; the multifaceted volcanism of the Serdán-oriental basin, México

Abstract

The intermontane Serdán-Oriental basin (SOB), located in the Trans-Mexican Volcanic Belt, records a highly contrasting volcanic field with nearly 166 monogenetic volcanoes, including cones, maars, tuff rings, domes, and lava flows, with basaltic to rhyolitic compositions and from effusive to explosive, and magmatic to phreatomagmatic eruptive styles. Even when this volcanic field has been the focus of several volcanological studies, an evolutive model of its volcanism and its implications has not been reported. This is a geological study of SOB volcanism based on the spatio-temporal evolution and characteristics of its volcanoes. For this, new and published data is integrated, including chronostratigraphic, geochemical, and petrological observations, which were further processed and analyzed by GIS tools. The resulting model indicates that volcanism has been continuous from the middle Pleistocene to the Holocene. Based on parameters such as erupted magma chemistry and volcanic landforms, it can be classified into the following volcanic groups: Group 1 is mafic in composition, forming cones and lava flows during the middle Pleistocene (490 to 190 ka). Group 2 comprises predominantly andesitic volcanism characterized by cones and dome clusters erupted during the middle Pleistocene (250 to 200 ka), partially coeval with Group 1. Group 3 is characterized by rhyolitic volcanism associated with the emplacement of domes in the central part of the SOB during the middle to upper Pleistocene (220 to 24.5 ka). Group 4 includes a predominantly basaltic to andesitic volcanism with minor rhyolitic composition, with a characteristic occurrence of phreatomagmatic and magmatic activity, forming maars and tuff rings, scoria cones, and lava flows during the middle Holocene (12.2 to 6.25 ka). The youngest Group occurs in the upper Holocene (<7.5 ka), and it is marked by mafic volcanism in the form of cones and lava flows, as well as by the emplacement of the voluminous Las Derrumbadas rhyolitic twin domes. Overall, the geochemical data shows a bimodal compositional character with a gap of dacitic magmas, compatible with a general scenario dominated by felsic melt extraction from highly crystalline magma reservoirs. Eruptive rate calculations indicate a general increase with time, which goes from <0.18 km3/ky in the first three groups to 1 and 2.9 km3/ky in groups 4 and 5, respectively. Lastly, density maps and lineaments of the eruptive vents, together with crater elongations, allowed the identification of the spatial trends of the SOB volcanism and a comparison with the existing regional major tectonic structures characterizing the local basement. These findings are relevant to understanding the eruptive nature of this active volcanic field and its highly contrasting and multifaceted volcanism.