BSSA 105:1, Electronic Supplement to Galli et al.

Electronic Supplement to
Holocene Paleoearthquakes and Early–Late Pleistocene Slip-Rate on the Sulmona Fault (Central Apeninnes, Italy)

by Paolo Galli, Biagio Giaccio, Edoardo Peronace, and Paolo Messina

Tephrostratigraphic Analyses: Method and Results

Major and minor element compositions were determined on micropumice fragments and/or glass shards from the tephras Morrone T1 (Fig. S1) and T3 and on melt inclusions in clinopyroxene crystals from the layer Morrone T2 (Fig. S2; see Fig. 1a in the main article for sample location). The analyses were carried out at the Istituto di Geologia Ambientale e Geoingegneria of the Consiglio Nazionale delle Ricerche (IGAG-CNR) in Rome, Italy, using a Cameca SX50 electron microprobe equipped with a five-wavelength dispersive spectrometer. Operating conditions were as follows: accelerating voltage, 15 kV; beam current, 15 nA; beam diameter, 10–15 μm; and counting time, 20 s per element. The following standards were used: wollastonite (silicon and calcium, Si and Ca), corundum (aluminium, Al), diopside (magnesium, Mg), andradite (iron, Fe), rutile (titanium, Ti), orthoclase (potassium, K), jadeite (sodium, Na), phlogopite (fluorine, F), potassium chloride (chlorine, Cl), baritina (sulphur, S), and metals (manganese, Mn). The Ti content was corrected for the overlap of the Ti-Kα peaks. In order to evaluate the accuracy of the electron microprobe analyses, three international secondary standards (Kakanui augite, Icelandic Bir-1, and rhyolite RLS132 glasses, from the United States Geological Survey) were measured prior to each analytic run. Mean precision was ~1% for silicon dioxide (SiO₂); ~2% for aluminium oxide (Al₂O₃); 7% for potassium oxide (K₂O), calcium oxide (CaO), and iron oxide (FeO); and 8%–10% for the other elements.

Morrone T1 (MT1). It is a centimeter-thick, yellowish, strongly weathered ash layer made of highly vesicular aphyric micropumices (Fig. S1). The composition of handpicked fresh glass shards from tephra MT1 shows a relatively wide spectrum (Table S1), which in TAS diagram results in an elongated, linear trend parallel to the line separating the trachyte–phonolite and latite–tephyphonolite fields (Fig. S3a). Based on this peculiar variable composition and the chronological constraints (see main text), the MT1 tephra can be unambiguously correlated to the widespread late glacial tephra from the caldera-forming Neapolitan Yellow Tuff eruption (Fig. S3a), occurred in Campi Flegrei volcanic field around 15 ka (e.g., Tomlinson et al., 2012).
Morrone T2 (MT2). It is a decimeter-thick, partially reworked layer made of coarse leucite-bearing greyish scoria with abundant, up to millimeter-size clinopyroxene, leucite, and peculiar coarse (up to centimeter-size) flogopite crystals (Fig. S2). Melt inclusions in clinopyroxene crystals from the layer MT2 are foiditic in composition (Table S1), which is the typical and peculiar compositions of the glass from the Colli Albani pyroclasts (e.g., Giaccio et al., 2013). Although on the basis of the available chronological constraints and of the strontium (Sr) isotope composition (Giaccio et al., 2007), the layer MT2 might be compatible with either the early (~70 ka) or late (40–36 ka) activity of the Albano Maar, the compositions of the melt inclusions in clinopyroxene from the MT2 layer match those from the Albano-7 unit (Fig. S3c) (Giaccio et al., 2009), thus constraining the correlation of this foiditic distal layer to the last (~36 ka) Albano Maar eruption.
Morrone T3 (MT3). It is a 7 cm-thick fallout layer made of a basal fine ash level of highly vesicular grey micropumices grading upward to a level of coarser ash made of both whitish leucite-free and leucite-bearing micripumices, sanidine and black mica crystals, and reddish lithics. Glass from tephra MT3 is mainly phonolitic in composition with a relatively wide range of the SiO₂ content from ~61 wt% to 55 wt% (Table S1; Fig. S3b). Compositional and lithological features of the MT3 layer (i.e., thickness, grain-size vertical variability, and the presence of the idiosyncratic reddish lithic fragments) enable us to unambiguously correlate it to the homolog tephra SUL5-1c previously found in Sulmona lake sediments and attributed to the Fall A pumice unit (Giaccio et al., 2014) from a Plinian eruption that occurred in the Mt. Sabatini volcanic district (Sottili et al., 2004) ~499 ka (Marra et al., 2014).

Table

Table S1. Major-element compositions (normalized to 100 wt%) of glass shards (Morrone T1 [MT1] and Morrone T3 [MT3]) and melt inclusions in clinopyroxene crystals (Morrone T2 [MT2]) from the three investigated tephras (see details in main text).

Figures

Figure S1. The Neapolitan Yellow Tuff tephra layer sampled below the top surface of one alluvial fan in the Mount Morrone slope (tephra 1 in Fig. 1a,c of the main article).

Figure S2. Albano-7 tephra, sampled in the Santopadre alluvial fan (tephra 2 in Fig. 1a,c). See also Figure 2a of the main article for other locations.

Figure S3. Total alkali versus silica and representative Harker diagrams (electron microprobe analyzer compositions) for glass from (a) the tephras Morrone T1 (MT1) and (b) Morrone T3 (MT3) and (c) for melt inclusion in clinopyroxene crystals from the Morrone T2 (MT3) and for their proximal/distal equivalent Neapolitan Yellow Tuff (NYT; ~15 ka), Sabatini Fall A (~499 ka), and Albano-7 (~36 ka), respectively. For comparison, the compositions of the melt inclusion in clinopyroxene crystals from the Albano-1–3 units are also plotted. Original data sources: NYT, Tomlison et al. (2012); Fall A Sabatini, Marra et al. (2014); Fall A Mercure (SC3) and Fall A Sulmona (SUL5-1c), Giaccio et al. (2014); and Albano-7 and Albano-1–3, Freda et al. (2006).

Geological Background

Figure S4. View looking north of the rock-fault scarp of the eastern Sulmona fault splay (A). (B) shows the main basal fault buried by the alluvial fan (D), and (C) shows Early Pleistocene breccias hanging over the present plain.

Figure S5. Oblique aerial view looking southeast of the rock-fault scarp of the eastern Sulmona fault splay on the Mount Morrone slope.

Figure S6. View looking southeast of the Mount Morrone slope. Arrows indicate the two strands of the basal fault near Popoli investigated by paleoseismological trenches (asterisk), and the upper Sulmona terrace (UST) and Santopadre alluvial fan (A) are identified (see also Fig. 2a).

Figure S7. View looking northeast of the trench 1 site (asterisk in Fig. S6).

Figure S8. View looking southeast of the trench 1 exposure (see Fig. 3).

Figure S9. Detail of the fault zone in trench 1 (see Fig. 3).

Figure S10. View looking southeast of the trench 2 exposure (see Fig. 4).

Figure S11. View looking east of the trench 3 exposure (see Fig. 4).

Figure S12. Detail of the fault zone in trench 4 (see Fig. 5).

Figure S13. View looking east of the trench 4 exposure (see Fig. 5).

Figure S14. Current image of the Roman epigraph attesting to the earthquake of the second century A.D.. The epigraph was first published in Cremona by Allegranza (1781, p. 227), who personally read the text when the stone was still walled in the floor facing the main door of the San Clemente a Causaria Abbey (the Interpromium site in Fig. 1a): “[…]SVLMONII PRIMVS ET FORTVNATVS /[P]ONDERARIVM PAGI INTERPROMINI /TERRAEMOTVS DILAPSVM A SOLO /[S]VA PECVNIA RESTITVERVNT.”

References

Allegranza, G. (1781). Opuscoli Eruditi latini ed italiani del P. M. Giuseppe Allegranza, Lorenzo Manini Regio Stampadore, Cremona, Italy, 320 pp.

Freda, C., M. Gaeta, D. B. Karner, F. Marra, P. R. Renne, J. Taddeucci, P. Scarlato, J. Christensen, and L. Dallai (2006). Eruptive history and petrologic evolution of the Albano multiple maar (Alban Hills, central Italy), Bull. Volcanol. 68, 567–591.

Giaccio, B., A. Sposato, M. Gaeta, F. Marra, D. M. Palladino, J. Taddeucci, M. Barbieri, P. Messina, and M. F. Rolfo (2007). Mid-distal occurrences of the Albano Maar pyroclastic deposits and their relevance for reassessing the eruptive scenarios of the most recent activity at the Colli Albani Volcanic District, central Italy, Quaternary Int. 171/172,160–178.

Giaccio, B., F. Marra, I. Hajdas, D. B. Karner, P. R. Renne, and A. Sposato (2009). 40Ar/39Ar and 14C geochronology of the Albano Maar deposits: Implications for defining the age and eruptive style of the most recent explosive activity at Colli Albani Volcanic District, central Italy. J. Volcanol. Geoth. Res. 185, 203–213.

Giaccio, B., P. Galli, E. Peronace, I. Arienzo, S. Nomade, G. Cavinato, M. Mancini, P. Messina, and G. Sottili (2014). A 560–440 ka tephra record from the Mercure basin, southern Italy: Volcanological and tephrochronological implications, J. Quaternary Sci. 29, 232–248.

Giaccio, B., I. Arienzo, G. Sottili, F. Castorina, M. Gaeta, S. Nomade, P. Galli, and P. Messina (2013). Isotopic (Sr-Nd) and major element fingerprinting of distal tephras: An application to the Middle–Late Pleistocene markers from the Colli Albani volcano, central Italy, Quaternary Sci. Rev. 67, 190–206.

Marra, F., G. Sottili, M. Gaeta, B. Giaccio, B. Jicha, M. Masotta, D. M. Palladino, and D. M. Deocampo (2014). Major explosive activity in the Monti Sabatini Volcanic District (central Italy) over the 800–390 ka interval: Geochronological–geochemical overview and tephrostratigraphic implications, Quaternary Sci. Rev. 94, 74–101.

Sottili, G., D. Palladino, and V. Zanon (2004). Plinian activity during the early eruptive history of the Sabatini Volcanic District, central Italy, J. Volcanol. Geoth. Res. 135, 361–379.

Tomlinson, E. L., I. Arienzo, L. Civetta, S. Wulf, V. C. Smith, M. Hardiman, C. S. Lane, A. Carandente, G. Orsi, M. Rosi, W. Müller, and M. A. Menzies (2012). Geochemistry of the Phlegraean Fields (Italy) proximal sources for major Mediterranean tephras: Implications for the dispersal of Plinian and co-ignimbritic components of explosive eruptions, Geochim. Cosmochim. Acta 93, 102–128.

[ Back ]