Correlating weathered, microphenocryst-rich, intermediate tephra: An approach combining bulk and single shard analyses from the Lepué Tephra, Chile and Argentina

Abstract

Correlating weathered, microphenocryst-rich, intermediate tephra: an approach combining bulk and single shard analyses from the Lepué Tephra, Chile and Argentina.

The Fucino 250–170 ka tephra record: New insights on peri-Tyrrhenian explosive volcanism, central mediterranean tephrochronology, and timing of the MIS 8-6 climate variability

“…However, such a great potential strongly depends on the completeness and quality of the available tephra geochemical and geochronological datasets that allow their unambiguous identification through diagnostic features, among which the geochemical glass composition is one of the most powerful (e.g., Smith and Westgate, 1968;Hayward, 2011;Lowe et al, 2017;Pearce et al, 2019). elements, Sr-Nd isotope ratios and provided new 40 Ar/ 39 Ar ages.…”

Refinement of the tephrostratigraphy straddling the northern Patagonian Andes (40–41°S): new tephra markers, reconciling different archives and ascertaining the timing of piedmont deglaciation

“…2017a; Pearce et al . 2019). For intensely microlitic and/or weathered and cemented fine‐grained tephra beds we utilised SN‐ICP‐MS (Table 2, see SI –Analytical methods ).…”

“…A southern-sourced inter-regional tephra marker Chana tephra (Cha-1) was originally described and defined by Naranjo and Stern (2004) at Paso Lago Blanco, ~10 km northeast of Volcán Chaitén and ~220 km south of our study area. Close to its Chaitén eruptive source, Cha-1 closely overlies fall and surge sub-units of Lepué Tephra (Alloway et al 2017b;Pearce et al 2019) (see Fig. 17A).…”

“…pumiceous lapilli and/ or vitric-rich ash beds) amenable to EMPA (Table 1, see SI -Analytical methods). Since scoriaceous tephra beds were stratigraphically numerous we opted to avoid acquiring EMP analyses on the entire inventory simply on account of their highly variable microphenocryst content, which, for many, can impede the acquisition of meaningful glass matrix data (Alloway et al 2017a;Pearce et al 2019). For intensely microlitic and/or weathered and cemented fine-grained tephra beds we utilised SN-ICP-MS (Table 2, see SI -Analytical methods).…”

High-resolution stalagmite stratigraphy supports the Late Holocene tephrochronology of southernmost Patagonia

“…Site-dependent, potentially intense weathering processes in acidic peatland ecosystems 14 can compromise geochemical fingerprinting methods for tephra correlation 3 . Chemical weathering over long periods strongly alters the composition of volcanic glass and embedded phenocrysts, leading to drastic changes of major and trace element concentrations 15,16,17 .…”