A crystal concentration method for calculating ignimbrite volume from distal ash-fall deposits and a reappraisal of the magnitude of the Campanian Ignimbrite

A chemostratigraphic study of the Campanian Ignimbrite eruption (Campi Flegrei, Italy): Insights on magma chamber withdrawal and deposit accumulation as revealed by compositionally zoned stratigraphic and facies framework

“…The 39 ka Campanian Ignimbrite (CI;De Vivo et al, 2001;Fedele et al, 2008), emplaced during a catastrophic explosive event having a magnitude of 7.2 (Scarpati et al, 2014), is considered the most powerful eruption ever to have occurred in the Neapolitan area. It was accompanied by a huge volcano-tectonic collapse, giving birth to the Campi Flegrei caldera (CFc; Rosi and Sbrana, 1987;Perrotta et al, 2006;Scarpati et al, 2013).…”

“…The plinian phase was followed by a collapsing column phase (Scarpati et al, 2014) during which an impressive pyroclastic density current was generated, spreading over an area of N30,000 km 2 and managing to surmount mountain ridges up to 1000 m high (Fisher et al, 1993). This phase produced a massive, mostly welded, grey ignimbrite sheet in medial areas (e.g., Barberi et al, 1978;Fisher et al, 1993;Scarpati and Perrotta, 2012;Scarpati et al, 2015a) and a proximal accumulation of lithic breccias, welded horizons and unconsolidated pumiceous deposits along the caldera rim (the Breccia Museo; e.g., Perrotta and Scarpati, 1994;Melluso et al, 1995;Fedele et al, 2008).…”

“…About 16 km 3 of co-plinian ash and 100 km 3 of cogenetic co-ignimbrite ash fall were dispersed and emplaced in the eastern Mediterranean Sea and eastern Europe (e.g., Perrotta and Scarpati, 2003;Pyle et al, 2006;Costa et al, 2012;Engwell et al, 2014). Although reported estimates for the total volume of erupted magma have historically oscillated from 60 up to 300 km 3 DRE (dense rock equivalent), a very recent non-geometric model based on the enrichment factor (EF; Walker, 1972) suggests much smaller values, between 49 and 72 km 3 DRE (see Scarpati et al, 2014 and references therein).…”

“…Phenocryst load is commonly b10 vol% [3.5 wt% for USAF, 6.4 wt% for WGI pumice and 6 wt% for CPF; Scarpati et al (2014)] and is generally slightly higher in pumice with respect to scoria samples, regardless of the stratigraphic unit. The main mineral phases are alkali feldspar, clinopyroxene, plagioclase, opaques, biotite and apatite (in decreasing order of abundance), whose compositions basically reflecting those already reported for medial CI juvenile clasts (Civetta et al, 1997, Pappalardo et al, 2002, Marianelli et al, 2006Fowler et al, 2007.…”

Campanian Ignimbrite volcanism, climate, and the final decline of the Neanderthals

“…To determine the volcanic injection parameters, we relied on published studies of CI ash dispersal (Costa et al, 2012), CI petrology (Signorelli et al, 1999), and erupted volume (Scarpati et al, 2014). Costa et al (2012) found that the pattern of CI ash dispersal is most consistent with a late autumn or early winter eruption.…”