Youngest Iberian Holocene volcanic eruptions and paleoenvironmental evolution of a barrier-paleolake in the Garrotxa Volcanic Field (NE Spain)

Abstract

Volcanic eruptions are key drivers of climate variability, with complex environmental consequences at regional and local scales that are rarely documented in high-resolution sedimentary records. In this work we present the results of a 15 m long paleolake core (Pla de les Preses core, Vall d’en Bas, Girona, NE Spain) covering the Late Pleistocene-Holocene transition. Multiproxy analyses including chronostratigraphy, sedimentology, micropalaeontology and geochemistry are used to reconstruct the paleoenvironmental framework of the Late Pleistocene-Holocene transition and to detect the youngest Holocene volcanic eruptions in the Garrotxa Volcanic Field (GVF) and the Iberian Peninsula. The studied sedimentary record covers the last ca. 13.5 ka cal BP and was punctuated by several rapid climatic changes including the 9.3, 8.2 and 7.1 ka events, affecting the hydrological evolution of a barrier-lake formed due to the volcanic damming of the Fluvià river. Sedimentological and geochemical analyses unveil the environmental history of Vall d’en Bas valley; the formation of a lacustrine area within a fluvial environment around 13.5 ka cal BP and later a wetland phase between 9.3 and 8.2 ka cal BP. Abrupt sedimentary changes marking the onset and demise of the wetland phase were linked to hemispheric cooling and drying events (e.g. 9.3 and 8.2 ka cal BP), provoking a decline in the water table during these phases. In addition, 30 tephra layers are detected thorough the core, showing previously unknown intense volcanic activity from 13.5 to 8.3 ka cal BP in the GVF. In that sense, the Pla de les Preses sequence provides, for the first time, evidence for early Holocene volcanic activity in NE Iberia that should be taken into account in future tephra studies in the western Mediterranean realm.

CatVolc: A new database of geochemical and geochronological data of volcanic-related materials from the Catalan Volcanic Zone (Spain)

“…Nonetheless, a recent study has detected 30 ash layers along a 15 m long paleolake sediment core extracted in La Vall d'en Bas area (~7 km from Croscat volcano) suggesting intense volcanic activity from 13.5 to 8.3 ka cal BP in the GVF, based on 15 radiocarbon dates obtained from bulk sediment and Pinus sp. macrofossils (Iriarte et al, 2023;Revelles et al, 2023). However, at present, no direct correlation exists between these tephra layers and the volcanic deposits or eruptive vents in this volcanic field.…”

“…2). Recently, Iriarte et al (2023) analysed a 15 m long paleolake core in the GVF (Vall d'en Bas area, Fig. 2) covering the Late Pleistocene-Holocene transition.…”