Chapter 5

Abstract

This chapter focuses on the evolution through time of Paramillo de Santa Rosa Volcanic Complex, providing new information. The stratigraphy and geological map of the Paramillo de Santa Rosa Volcanic Complex in the Colombian Central Cordillera are presented using the concepts of traditional stratigraphy adapted to the needs of the volcanological environment such that lithostratigraphic units, lithosomes, and unconformities are integrated. Combining this information with new geochronological data, the eruptive history is described in two eruptive periods and six epochs interrupted by recurrent flank collapses and their associated debris avalanches and lahars, as well as time intervals characterized by the activation of processes such as erosion, reworking, and glacial reshaping. The volcanic complex has andesitic to dacitic volcanic products of calc-alkaline affinity, typical of a subduction zone along an active continental margin. The Paramillo de Santa Rosa Volcanic Complex comprises two major overlapping stratovolcanoes and the most recent coulée-dome at the summit of the volcano. Geochronological data indicate that the volcanic complex age extends from the Pleistocene. Chronologically, the major edifices correspond to the remnants of a first volcanic edifice called the Pre-Paramillo de Santa Rosa Volcano that dates from the early to the Middle Pleistocene, and the formation and development of a second edifice called Paramillo de Santa Rosa Volcano from the Middle Pleistocene to the Holocene. These volcanoes produced lava flows and pyroclastic deposits, together with debris avalanche and lahar deposits, as posteruptive processes. The maximum expected eruptive events are concentrated and dilute pyroclastic density currents produced at the summit of the volcano, likely, as a result of explosions and collapses of domes. The present study contributes to the knowledge of Quaternary volcanism of active volcanoes in the northern volcanic segment of Colombia, and confirms that the Paramillo de Santa Rosa Volcano is active and should be considered in local volcanic hazard assessment.

Chapter 7

“…This method aims to describe the types of volcanic rocks and deposits, reconstruct their vertical succession and their changes over time, characterize units bordered by unconformities, define their genesis and sources, and establish correlations among various rock units considering the complex, diverse, and episodic characteristics of the dominant processes in volcanic areas. Currently, this method has been applied in Colombia by the Grupo de Geología de Volcanes of the SGC on the Doña Juana Volcanic Complex (Pardo et al, 2016(Pardo et al, , 2019 and on the Paramillo de Santa Rosa Volcanic Complex (Pulgarín-Alzate et al, 2020). These studies used concepts from the International stratigraphic guide (Salvador, 1994) and involved the integrated use of lithological units combined with chronostratigraphic units, which led to the definition of lithostratigraphic units, lithosomes, and unconformities (Martí et al, 2018).…”

Volume 1

“…This chapter proposes a conceptual model of this system based on geological, geophysical, and geochemical studies conducted by the Grupo de Exploración de Recursos Geotérmicos of the SGC. Pulgarín-Alzate et al (2020), in chapter 5, present the constitution and origin of the Paramillo de Santa Rosa Volcanic Complex, located in the Central Cordillera. The authors interpret it as the result of a succession of events related to a subduction zone in an active continental margin between the early Pleistocene and the Holocene.…”

“…In chapter 6, written by Correa-Tamayo et al (2020), the Nevado del Huila Volcanic Complex located in the Central Cordillera is studied. The authors divide the eruptive activity of this volcano into three stages: Pre-Huila, Old Huila, and Recent Huila, that began in the early Pleistocene and produced two main volcanic edifices (Pre-Huila and Huila).…”