**1. Introduction**

Understanding volcanic rocks plays a crucial role in reconstructing the environment in various scales within volcanic rocks formations. Volcanic processes can act in a short time scale and still produce large volumes of eruptive products that commonly can misbalance the sedimentary budget of a sedimentary basin, regardless of their geoenvironmental position (e.g., marine, or terrestrial). Distal ash, on the other hand, can travel hundreds of kilometers away from their source and fall into the background sedimentary environment and can produce a very characteristic and sharp time marker across the entire region. This makes volcanic deposits excellent chronostratigraphy markers [1]. Volcanic processes are also diverse not only by the way coherent and fragmented source materials get generated (e.g., fragmentation style variations, eruption intensity diversity) but also by the way those materials get transported and accumulated. Large volumes of volcanic material can accumulate quickly (hours to days) and alter the entire drainage pattern of large regions. The same accumulated volcaniclastic deposits later can gradually get redeposited and altered by normal surface processes but can provide volcanic detritus over prolonged time along the transportation arteries that eventually lead to marine basins [2, 3]. While this process seems to be a slow and gradual way effectively remove large volume of volcanic deposits from source regions and disperse it over large territories, such processes can also take place in a dramatic and abrupt fashion. Massive breakout lahars can mobilize large volumes of water and damp their sediments suddenly over large areas. On many occasions, like in the Taupo Volcanic Zone in New Zealand, large volumes of calderaforming silicic eruptions had modified the landscape dramatically and promoted the formation of large lake systems, which, from time to time, initiated breakout lahars moving large volumes of volcaniclasts to other sedimentary basins [4]. Over time, major sedimentary basins from terrestrial to marine produce massive successions of complex multisource volcaniclastic aprons, fans, and basin fills. In ancient settings, such basins and their complex volcaniclastic successions can be the only "messengers" of former high-intensity volcanism, especially if the preserved volcaniclastic rocks are preserved as part of tectonically dissected terrains.

Volcaniclastic sedimentology has evolved in recent years dramatically. Primary eruption-fed processes considered to produce fragmented volcanic materials generate pyroclasts that can start their journey through initial primary volcanic processes that later interact with the normal sedimentary environment, making it increasingly

### *Updates in Volcanology - Linking Active Volcanism and the Geological Record*

#### **Figure 1.**

*Bibliometric surveys based on Scopus data for search terms of "volcaniclastic" and "sediment" as well as "pyroclastic" and "sediment" within keyword, title, and abstract documents.*

difficult to distinguish the effect of the primary volcanic and the background sedimentary processes. This difficulty manifests in the way how we describe and interpret the preserved volcanic material in the geological record. In the past decades, various terminologies have appeared with an aim to provide a clear method to document objectively volcanic rocks, keeping the descriptive and interpretative aspects of the nomenclature separated [5]. It is apparent that over time, such terminologies have become more and more process related, expressing the strength of the link between primary (eruption-fed) and secondary (background sedimentation-dominated) processes [6–8]. In the past decades, entire volcaniclastic sedimentology schools have formed with key research groups (**Figure 1**) with diverse geological backgrounds, demonstrating the vitality of volcaniclastic sedimentology. Moreover, in recent years, the geology-based approach has reemerged, and new research has applied basic geological rules to look at volcanoes through volcano geology perspective [9, 10].
