*Effusive Monogenetic Volcanism DOI: http://dx.doi.org/10.5772/intechopen.94387*

*Updates in Volcanology – Transdisciplinary Nature of Volcano Science*

volcanoes classification.

comprehension for future studies.

**2. Effusive monogenetic volcanoes**

Lava domes in general have been mostly described as part of eruptions in polygenetic, intermediate to acidic volcanoes (e.g. [17]). From there, several types have been defined. Based on the growing mechanism, they are either endogenous whether they expand by intrusion of new magma or exogenous whether they enlarge by extrusion of it [18]; they are also called cryptodomes whether the magma did not reach the surface [19]. Furthermore, based on the geoform, they have received different names such as tortas, platy, axisymmetric, lobate, spines or peléean-type, upheaved plugs, viscous coulées lava streams, among others [17, 20–22]. As minor centers (i.e. as monogenetic volcanoes), the only classification that exist for our knowledge, is that outlined by De Silva and Lindsay [23] who grouped them in: 1) lava domes or tortas, 2) coulées, 3) peléean, and 4) upheaved plugs, based on their morphology. Individual monogenetic lava flows, in addition, are not part of this or any other classification scheme with the exception of the scutulum, low shields or small-shields (cf. [24, 25] that are mentioned by De Silva and Lindsay [23] within the mafic monogenetic

It is worth mentioning that the concept of "monogenetic" volcanism has even been considered in association with 1) Large Igneous Provinces (LIPs) that are overwhelmingly effusive, but formed in very short period of time in single flare ups [26], or 2) effusive dominated fields that are smaller than typical Large igneous provinces but significantly bigger than a "normal" monogenetic field [25]. In this work, however, we refer to small-volume monogenetic volcanoes, understood as

We herein propose the expansion of the existing monogenetic classification scheme after including the effusive volcanoes based on the above mentioned. This classification is based on their geoform, similarly to the explosive volcanoes. Furthermore, we provide a framework of the processes that act during the magma ascent and cause differentiation to produce intermediate to evolved volcanic products. Thus, we outline magmatic plumbing system options, which include crustal magma reservoirs as zones for detaching magma batches. Finally, we provide an overview of this particular poorly known volcanism worldwide, contributing to the monogenetic

The way that magma is monogenetically released to the Earth surface is related to the internal magma dynamic that occurred in the last dozens of meters [27]. It also depends on the form and dimensions of the conduit with the ascending magma. Whether the magma encounters water en route, a process known as MFCI (Molten-Fuel Coolant Interaction) occurs and therefore, it drives the eruption [28, 29]. In this case, the eruptive style depends mostly on the amount of water that the magma encounters [30] and the lithology where this water (usually an aquifer) is stored (e.g. sediments vs. fractured metamorphic rocks) (e.g. [31–33]; this last also associated with the easiness for the water to be released. However, whether the magma reaches the surface without any interaction with water, the eruption may occur in two ways: 1) explosive, whether the magma is fragmented by the volatiles dynamics (i.e. exsolution, nucleation, growth and coalescence) associated with pressure decreasing, or 2) effusive, whether degassing is effective, linked to bubbles interconnection avoiding the magma fragmentation [34]. The first eruptive manner builds scoria cones (e.g. the historical Jorullo [35–37] and Paricutín volcanoes in México [38]), while the second one produces lava bodies (e.g. The Villamaría-Termales Monogenetic Volcanic Field in Colombia; [5]). As previously mentioned, these emissions are commonly part of the explosive activity forming any kind of pyroclastic cone; however, they can also

small magma batches reaching the surface dispersed and episodically.

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dominate and create individual effusive volcanoes (**Figure 1**). Because of this, we propose here these effusive products as part of a monogenetic volcano classification scheme and add them to those produced by magmatic activity (**Figure 2**). Accordingly, we propose to distinguish them between lava domes, coulées, small-shields and lava

### **Figure 1.**

*Effusive monogenetic volcanoes. (A) Güneydag lava dome in Anatolia, Turkey; (B) Victoria lava dome and Victoria lava flow in Manizales, Colombia; (C) El Bosque small-shield in Morelia, México. (D) Tesorito couleé in Manizales, Colombia.*

### **Figure 2.**

*Classification scheme of monogenetic volcanoes and their relationship with their eruptive style.*

flows based on their geoform. The construction of every volcano is linked to the internal dynamics of the magma, but also to the form and dimension of the ascending conduit, the interaction of the conduit with the surface, and the topography where the magma is released. Every factor should be in-depth investigated. An overview of these elements is the topic of the following sections.
