Abstract
The Southern and Austral Volcanic Zones of the Andes comprise 74 volcanic centres with known post-glacial activity. At least 21 of these have had one or more large explosive eruptions in the late Quaternary, dispersing tephra over vast areas. These tephra layers therefore have great potential as tephrochronological marker horizons in palaeoenvironmental studies in southern Chile and Argentina, a region that is particularly useful to study climate dynamics of the southern hemisphere. However, to date tephrochronology has rarely been fully utilised in this region as a correlation and dating tool. Here we review the existing post-glacial tephrostratigraphic record of the Southern and Austral Volcanic Zones, and compile a database of known occurrences of tephra from these volcanoes in ice and lacustrine, marine, peat, and cave sediment records. We address the inconsistencies in and revisions of the tephrostratigraphies presented in prior literature, and discuss the challenges in correlating tephras and the limitations of the tephrostratigraphic record in this area. This study highlights the many gaps that still exist in our knowledge of the eruptive histories of these volcanoes, but also reveals the largely under-utilised potential of tephra as a correlation tool in this region. This is exemplified by the severe lack of adequate geochemical analysis of tephra layers preserved in many lacustrine and peat sediment sections, which are particularly important tephrostratigraphic records in southern Chile and Argentina due to the paucity of surface preservation.
Highlights
This technique is based on the principle that tephra layers representisochronous marker horizons, because they are the result of direct fallout of volcanic ash from the atmosphere during and immediately after volcanic eruptions, which are generally short-lived in geological terms
We present a critical review of the late Quaternary tephrostratigraphic record as it is known from scientific literature for the Andean Southern and Austral Volcanic Zones, which span the approximate latitude range 33e55S (Fig. 1)
The Andean arc is a segmented volcanic arc along the western margin of South America (Stern, 2004). It is divided into four main volcanic zones; the Northern Volcanic Zone (NVZ; 5Ne2S), Central Volcanic Zone (CVZ; 14e27S), Southern Volcanic Zone (SVZ; 33e47S), and Austral Volcanic Zone (AVZ; 49e55S)
Summary
Tephrochronology is widely employed as a stratigraphic correlation tool in a broad range of disciplines, including (but not limited to) archaeology (e.g., Prieto et al, 2013; Riede and Thastrup, 2013), palaeoclimatology (e.g., Davies et al, 2012; Elbert et al, 2013), palaeoecology (e.g., Buckland et al, 1980; McCulloch and Davies, 2001), palaeogeomorphology (e.g., Stern et al, 2011; Dugmore and Newton, 2012), and volcanology (e.g., Shane, 2000; Watt et al, 2011). We present a critical review of the late Quaternary tephrostratigraphic record as it is known from scientific literature for the Andean Southern and Austral Volcanic Zones, which span the approximate latitude range 33e55S (Fig. 1) They comprise 74 volcanic centres thought to have been active during post-glacial times (Global Volcanism Program, GVP, http://volcano.si.edu/; Large Magnitude Explosive Eruptions database (LaMEVE), http:// www.bgs.ac.uk/vogripa; Crosweller et al, 2012; Siebert et al, 2010), ranging from clusters of (monogenetic) cones to central stratovolcanoes and large volcanic complexes. As the eruptive histories of specific volcanoes become better known, or additional lithological data from sediment cores becomes available, new information could be integrated into this record
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