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Abstract

Figures and Tables

Supplementary Figures and Tables

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Introduction

Volcanism began at Mount Etna, Europe’s largest and most active volcano, at ~0.5 Ma (Gillot et al., 1994

Gillot, P.Y., Kieffer, G., Romano, R. (1994) The evolution of Mount Etna in the light of potassium-argon dating. Acta Vulcanologica 5, 81–87.

), with ancient lavas now exposed around the perimeter of the modern-day edifice. Tholeiitic lavas were overlain by transitional and alkaline sequences starting at ~230 ka (Gillot et al., 1994

Gillot, P.Y., Kieffer, G., Romano, R. (1994) The evolution of Mount Etna in the light of potassium-argon dating. Acta Vulcanologica 5, 81–87.

; Branca and Del Carlo, 2004

Branca, S., Del Carlo, P. (2004) Eruptions of Mt. Etna during the past 3,200 Years: A revised compilation integrating the historical and stratigraphic records. In: Bonaccorso, A., Calvari, S., Coltelli, M., Del Negro, C., Falsaperla, S. (Eds.) Mt. Etna: Volcano Laboratory. American Geophysical Union, Washington, D.C., 1–27.

). Mt. Etna sits on the northern edge of the African plate at the European-African collision zone and the western hinge of escarpments dividing it from where the Ionian slab descends beneath the Aeolian arc (Fig. S-1, Supplementary Information). Volcanism has been attributed to the manifestation of mantle upwelling independent of, or in response to, a slab tear (e.g., Gasperini et al., 2002

Gasperini, D., Blichert-Toft, J., Bosch, D., Del Moro, A., Macera, P., Albarède, F. (2002) Upwelling of deep mantle material through a plate window; evidence from the geochemistry of Italian basaltic volcanics. Journal of Geophysical Research 107, 2367.

), subduction-related fluid-triggered melting (e.g., Armienti et al., 2007

Armienti, P., Tonarini, S., Innocenti, F., D'Orazio, M. (2007) Mount Etna pyroxene as tracer of petrogenetic processes and dynamics of the feeding system. In: Beccaluva, L., Bianchini, G., Wilson, M. (Eds.) Cenazoic volcanism in the Mediterranean Area. Geological Society of America Special Paper 418, 265–276.

and references therein) or enhanced decompression melting resulting from convective anomalies (Gvirtzman and Nur, 1999

Gvirtzman, Z., Nur, A. (1999) The formation of Mount Etna as the consequence of slab rollback. Nature 401, 782–785.

; Schellart, 2010

Schellart, W.P. (2010) Mount Etna–Iblean volcanism caused by rollback-induced upper mantle upwelling around the Ionian slab edge: An alternative to the plume model. Geology 38, 691–694.

).

Magmatic products of the early Etna centres, including those of the ancient alkali centres active at ~200–100 ka, bear mantle-derived isotopic signatures consistent with contributions from both enriched and depleted source components (Marty et al., 1994

Marty, B., Trull, T., Lussiez, P., Basile, I., Tanguy, J.-C. (1994) He, Ar, O, Sr and Nd isotope constraints on the origin and evolution of Mount Etna magmatism. Earth and Planetary Science Letters 126, 23–39.

; Tanguy et al., 1997

Tanguy, J.-C., Condomines, M., Kieffer, G. (1997) Evolution of the Mount Etna magma: Constraints on the present feeding system and eruptive mechanism. Journal of Volcanology and Geothermal Research 75, 221–250.

). Though more recent Etna volcanic products exhibit distinctive signs of assimilation in the form of elevated Sr isotopic values and large ion lithophile element enrichments (Tonarini et al., 1995

Tonarini, S., Armienti, P., D'Orazio, M., Innocenti, F., Pompilio, M., Petrini, R. (1995) Geochemical and isotopic monitoring of Mt. Etna 1989-1993 eruptive activity: bearing on the shallow feeding system. Journal of Volcanology and Geothermal Research 64, 95–115.

), the degree to which crustal contamination influenced early alkaline products is uncertain. Similarly, magmatic processes between mantle melting regions and shallow reservoirs supplying volcanic activity remain enigmatic. In this study, we combine clinopyroxene (cpx) barometry, trace element concentrations, and Pb, Hf, and Nd mineral-whole rock (WR) isotopic (dis)equilibria to constrain source compositions and differentiation depths of magmas feeding lavas erupted at Timpe Santa Caterina (TSC). The advantage of employing these three isotopic systems together lies in the coupling of the slowly diffusing Hf and Nd with the more rapidly diffusing Pb, thereby providing the potential to infer magma assembly processes prior to eruption during this early period.

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Sample Selection and Analytical Methods

Lavas at TSC encompass the whole ancient alkaline magmatism period at Etna, from 220 ka near sea level to likely <100 ka exposed atop the sea cliff (Gillot et al., 1994

Gillot, P.Y., Kieffer, G., Romano, R. (1994) The evolution of Mount Etna in the light of potassium-argon dating. Acta Vulcanologica 5, 81–87.

). Early trachybasaltic and basaltic flows, TSC-2 and TSC-3, are overlain by more alkalic basanites and phonotephritic lavas (TSC-7 and TSC-9). Flows selected for this study contain the most abundant large cpx from the TSC suite (Fig. S-2, Supplementary Information). Major and trace element and isotopic analytical details and data are provided in Tables S-1 to S-5 (Supplementary Information).

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Results and Discussion

Barometry. Observed cpx phenocrysts (>2 mm, large relative to other TSC lava phases) coupled with theoretical modelling of Etna compositions indicate early cpx crystallisation; hence cpx holds a potential record of pre-eruptive magma assembly processes (Armienti et al., 2009

Armienti, P., Gasperini, D., Perinelli, C., Putirka, K.D. (2009) A new model for estimating deep-level magma ascent rates from thermobarometry: an example from Mt. Etna and implications for deep-seated magma dehydration. Acta Vulcanologica 21, 145–158.

). Crystallisation temperatures and pressures, solved iteratively using a single-cpx thermometer and single-cpx barometer for hydrous systems (respectively, Eqs. 32d and 32b in Putirka, 2008

Putirka, K.D. (2008) Thermometers and barometers for volcanic systems. Reviews in Mineralogy and Geochemistry 69, 61–120.

), yielded temperatures of 1060–1175 °C and an average pressure of 0.34 ± 0.16 GPa (Fig. 1a,b). Thermobarometric model accuracy was evaluated using a literature dataset of >100 experimentally coexisting cpx-liquid pairs over a compositional range bracketing TSC lavas and cpx compositions (cf. Supplementary Information Table S-6 for equations, ranges, references, and selection criteria). As noted by Mollo et al. (2010)

Mollo, S., Del Gaudio, P., Ventura, G., Iezzi, G., Scarlato, P. (2010) Dependence of clinopyroxene composition on cooling rate in basaltic magmas: Implications for thermobarometry. Lithos 118, 302–312.

, single-cpx barometers can outperform liquid-based models for volatile-rich alkaline compositions. The single-cpx barometer for hydrous systems yields an average uncertainty of 0.17 versus 0.28 GPa for the cpx-liquid model of Putirka et al. (2003)

Putirka, K.D., Mikaelian, H., Ryerson, F., Shaw, H. (2003) New clinopyroxene-liquid thermometers for mafic, evolved, and volatile-bearing lava compositions, with applications to lavas from Tibet and the Snake River Plain, Idaho. American Mineralogist 88, 1542–1554.

for the compiled experiments, placing a lower bound of pressures recorded by TSC cpx at below 0.8 GPa, within the uppermost lithospheric mantle.

Crystallisation of TSC-2 and TSC-7 cpx generally occurred at depths centred around 0.5 GPa and 0.2–3 GPa, respectively (Fig. 1a), suggesting specific magma reservoir locations near the crystalline basement-granulite boundary and within the carbonate platform beneath Etna. More continuous polybaric crystallisation is apparent in TSC-3 and TSC-9. Combined with previous work on Etna lavas (see Supplementary Information), thermobarometry indicates that the bulk of ancient clinopyroxene phenocrysts crystallised between 0.5 and 0.2 GPa (Fig. 1b).

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Heterogeneous mantle sources for ancient Etna. Clinopyroxene trace element concentrations, when coupled with single-cpx barometry pressure estimates, place constraints on magma source compositions and crustal mixing depths. Cerium, incompatible in all major TSC phases, functions as a fractionation proxy and indicator of magma evolution. Two distinct crystallisation paths are apparent in TSC cpx: trends characterised by high Y/La (TSC-2, TSC-7) and low Y/La (TSC-3, TSC-9) when linked with Ce (Fig. 1c). Clinopyroxene from the 2001 eruption also follow the low-Y/La trend, as do other known historic and recent Etna cpx (Viccaro et al., 2006

Viccaro, M., Ferlito, C., Cortesogno, L., Cristofolini, R., Gaggero, L. (2006) Magma mixing during the 2001 event at Mount Etna (Italy): effects on the eruptive dynamics. Journal of Volcanology and Geothermal Research 149, 139–159.

). Scarlato et al. (2014)

Scarlato, P., Mollo, S., Blundy, J.D., Iezzi, G., Tiepolo, M. (2014) The role of natural solidification paths on REE partitioning between clinopyroxene and melt. Bulletin of Volcanology 76, 810, doi: 10.1007/s00445-014-0810-1.

have documented preferential HREE incorporation into cpx relative to LREE as a function of cooling rate, but in TSC phenocrysts, HREE-like Y has either negative or no correlation with major element chemistry associated with elevated cooling rates (e.g., Na, Al^IV, and Ti). Accordingly, we interpret the Y/La-Ce trends to reflect source characteristics beneath Etna over time rather than being a feature of crystallisation conditions.

Clinopyroxene grains record existence of magmas beneath Etna deriving from melting of both pyroxenitic and peridotitic mantle components. The source characterisation enabled by analysis of Y/La-Ce trends in Etna TSC cpx can also be used to evaluate the composition of cpx in pyroxenite and peridotite xenoliths from the nearby Hyblean Plateau (Fig. 1c). Clinopyroxene from Hyblean pyroxenite xenoliths plot along the high-Y/La TSC trend (Fig. 1c), which is reproduced with a primary melt generated by a heterogeneous source of 10 % dry pyroxenite and 90 % hydrated peridotite in which ~10 % of each lithology melts and mixes at 1.5 GPa. Figure S-3 shows hypothetical source compositions with up to 20 % pyroxenite to constrain model sensitivity (Supplementary Information). These lithologies, similar to those determined by Correale et al. (2014)

Correale, A., Paonita, A., Martelli, M., Rizzo, A., Rotolo, S.G., Corsaro, R.A., Di Renzo, V. (2014) A two-component mantle source feeding Mt.Etna magmatism: Insights from the geochemistry of primitive magmas. Lithos 184–187, 243–258.

modelling trace element systematics in primitive Etna WR samples <15 ka, are distinct from peridotitic cpx from the nearby Hyblean plateau that fall below the low-Y/La trend. Low Y/La in cpx may result from either a hydrated peridotite source or a more evolved melt of the mixed pyroxenite source following apatite saturation.

Isotopic (dis)equilibria. Most Etna mineral-WR pair isotopic work has focused on the Sr and Nd systems in recent lavas (e.g., Tonarini et al., 1995

Tonarini, S., Armienti, P., D'Orazio, M., Innocenti, F., Pompilio, M., Petrini, R. (1995) Geochemical and isotopic monitoring of Mt. Etna 1989-1993 eruptive activity: bearing on the shallow feeding system. Journal of Volcanology and Geothermal Research 64, 95–115.

), which generally exhibit more radiogenic Sr and less radiogenic Nd than ancient lavas. Within recent eruptive episodes, marked increases in WR ⁸⁷Sr/⁸⁶Sr are often accompanied by ⁸⁷Sr/⁸⁶Sr WR-cpx disequilibria (e.g., 0.70348 cpx core values accompanied by 0.70362 WR values in 2001 eruptives; Armienti et al., 2007

Armienti, P., Tonarini, S., Innocenti, F., D'Orazio, M. (2007) Mount Etna pyroxene as tracer of petrogenetic processes and dynamics of the feeding system. In: Beccaluva, L., Bianchini, G., Wilson, M. (Eds.) Cenazoic volcanism in the Mediterranean Area. Geological Society of America Special Paper 418, 265–276.

).

Our approach employing coupled Hf, Nd, and Pb isotopic signatures in ancient volcanics brings three distinct chemical affinities to bear on determining magma assembly, as recorded in cpx trace elements, at depths constrained by thermobarometry. As refractory elements diffusing slowly in clinopyroxene (cf. Van Orman et al., 2001

Van Orman, J.A., Grove, T.L., Shimizu, N. (2001) Rare earth element diffusion in diopside: influence of temperature, pressure, and ionic radius, and an elastic model for diffusion in silicates. Contributions to Mineralogy and Petrology 141, 687–703.

), Nd and Hf may be expected to retain isotopic signatures from early crystallisation depths and exhibit large isotopic disequilibria with hosting magmas subject to mixing with recharging, or assimilating magmas, carrying isotopically distinctive compositions immediately prior to eruption. In contrast, Pb diffuses relatively rapidly, making Pb isotope systematics an especially promising approach for placing constraints on magma residence times within the crust.

Since each separate cpx analysis represents digestion of multiple grains likely crystallised at different depths, reported isotopic values reflect an average over the polybaric cpx crystallisation history. However, sluggish Nd and Hf re-equilibration will manifest itself as WR-cpx disequilibria in cases of late-stage incorporation of any volumetrically significant isotopically distinct magma during the final stages of magma assembly.

Neodymium and Hf isotopic compositions (Fig. 2a) of TSC cpx and WR demonstrate they are insignificantly distinctive at the 2σ level. However, it is notable that all cpx have slightly more enriched Nd isotopic signatures that trend toward those of continental values. This could result from a recharge process of fresher mantle-derived material that drives eruption. Late-stage shallow contamination, by contrast, would impart enriched crustal signatures to the WR, presumably after cpx phenocryst formation. Though Hf and Nd isotopic data for sedimentary units directly beneath Etna are unavailable for comparison with cpx and WR values, Sicilian beach sand ε_Nd derived from the western extension of sedimentary units underlying Etna and crustal rocks of south and central Italy are all considerably more enriched (Fig. 2a; ε_Nd -10.3 to -16.0, Conticelli et al., 2002

Conticelli, S., D'Antonio, M., Pinarelli, L., Civetta, L. (2002) Source contamination and mantle heterogeneity in the genesis of Italian potassic and ultrapotassic volcanic rocks: Sr‚ Nd‚ Pb isotope data from Roman Province and Southern Tuscany. Mineralogy and Petrology 74,189–222.

; Brems et al., 2013

Brems, D., Ganio, M., Latruwe, K., Balcaen, L., Carremans, M., Gimeno, D., Silvestri, A., Vanhaecke, F., Muchez, P., Degryse, P. (2013) Isotopes on the beach, part 2: neodymium isotopic analysis for the provenancing of Roman glass-making. Archaeometry 55, 449–464.

). Such large differences make it unlikely that crustal sediments contributed to the Hf and Nd isotopic compositions observed in TSC cpx and WR materials. Rather, we infer that the isotopic signatures of these magmas were locked in at pressures corresponding, at minimum, to early cpx crystallisation at mid-crustal pressures of 0.5–0.2 GPa.

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Constraints on mantle mixing processes. In spite of barometric model uncertainties, sites of cpx crystallisation (shallow crust vs. lower crust/mantle) can be readily distinguished by the barometry and thus provide meaningful stratigraphic context for cpx isotopic values. The lack of significant disequilibrium can be explained by magma sources feeding Etna during the period of ancient alkaline eruptive activity being either broadly isotopically homogeneous or well mixed before eruption. The few reported WR-cpx pairs from 15–30 ka (Valle del Bove sequence; D'Orazio et al., 1997

D'Orazio, M., Tonarini, S., Innocenti, F., Pompilio, M. (1997) Northern Valle del Bove volcanic succession (Mt. Etna, Sicily): petrography, geochemistry and Sr-Nd isotope data. Acta Vulcanologica 9, 73–86.

) show corresponding Sr and Nd isotopic equilibria (isotopic differences <0.00002 and <0.00001, respectively) and results here extend this phenomenon back an additional 200 ka.

The interpretation of limited mixing is further supported by the observed equilibrium in three of the TSC lavas between cpx and WR Pb isotopic signatures (Fig. 2b). Only one WR-cpx pair (TSC-7) exhibits isotopic disequilibrium in the Pb isotope system just outside the range of external reproducibility. Limited crustal storage time implied by Pb isotopic cpx-WR equilibria also bolsters trace element records of crystallisation from heterogeneously sourced magmas being largely preserved in this system. Trace element modelling of sources is particularly valuable in cases where source isotopic signatures are relatively well homogenised.

The restricted isotopic range of TSC cpx and WR values contrasts sharply with the variety of Pb isotopic signatures observed for plagioclase-rich and magnetic splits of a finer-grained 260 ka Etna tholeiite (SdV-1) reported by Bryce and DePaolo (2004)

Bryce, J.G., DePaolo, D.J. (2004) Pb isotopic heterogeneity in basaltic phenocrysts. Geochimica et Cosmochimica Acta 68, 4453–4468.

and olivine-hosted melt inclusions from recent (2002) eruptions (Rose-Koga et al., 2012

Rose-Koga, E.F., Koga, K.T., Schiano, P., Le Voyer, M., Shimizu, N., Whitehouse, M.J., Clocchiatti, R. (2012) Mantle source heterogeneity for South Tyrrhenian magmas revealed by Pb isotopes and halogen contents of olivine-hosted melt inclusions. Chemical Geology 334, 266–279.

). Possible explanations include that these lavas may sample geographically different magma supplies or derive from magmas experiencing additional mixing immediately prior to eruption, as inferred from olivine in recent lavas (Kahl et al., 2011

Kahl, M., Chakraborty, S., Costa, F., Pompilio, M. (2011) Dynamic plumbing system beneath volcanoes revealed by kinetic modeling, and the connection to monitoring data: An example from Mt. Etna. Earth and Planetary Science Letters 308, 11–22.

). Variable Pb isotopic compositions in olivine-hosted melt inclusions could signify that minute amounts of isotopically distinct melts are simply insufficiently abundant to change the “deep”, dominant isotopic signal locked into cpx.

Lack of Hf-Nd-Pb isotopic disequilibria in ancient TSC lavas between cpx-WR pairs indicates that any mixing of isotopically distinct magmas supplying ancient Etna eruptions occurred at depths preceding cpx crystallisation. Melts then rose to the surface without significant assimilation in (and associated heat exchange with) shallow reservoirs.

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Conclusions

Thermobarometrically controlled elemental and isotopic analyses of clinopyroxene provide a means to reconstruct ancient magma assembly processes at Mt. Etna. Single-crystal cpx barometry places most phenocryst crystallisation within the mid-crust and permits distinction between deep and shallow processes when coupled with trace element and isotopic data. In situ trace element data from cpx allow for the assessment of pyroxenite vs. peridotite contributions to Etna magmas. Chemical signatures apparent in these ancient lavas as well as in modern products suggest that hydrated peridotite has been an important component of the magma source region over the history of this volcano. The present dataset further supports the interpretation that observed isotopic systematics in ancient Etna lavas resulted from mixing between depleted and enriched mantle sources, with volatile-bearing peridotite and pyroxenite components preferentially melting to generate volatile-rich ancient alkaline volcanism. Hf-Nd-Pb isotopic equilibria between TSC WR and cpx are consistent with a model of an ancient Etna plumbing system wherein melts were homogenised below mid-crustal depths and then rapidly transported to the surface without substantial assimilation of crustal material at pressures lower than 0.5 GPa. More extensive combinations of bulk isotopic stratigraphy with mineral barometric and trace element modelling as applied here are expected to afford opportunities to reconstruct the longevity of magmatic plumbing systems and deconvolve distinctive magma source regions feeding Mt. Etna through time.

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Acknowledgements

We thank Nilanjan Chatterjee, Julie Chouinard, Philippe Télouk, and Gerald Wynick for technical assistance, the Alfred University Center for Advanced Ceramic Technology (CACT), and Wendy Bohrson for comments on an earlier version of the manuscript. We appreciate thoughtful suggestions of Pietro Armienti, two anonymous reviewers, and the editorial handling by Bruce Watson, all of which improved the quality of our manuscript. Financial support from NSF grant EAR-1057611 to JGB and SAM, the UNH Undergraduate Research Opportunities Program to MM, and the French Agence Nationale de la Recherche (grant ANR-10-BLANC-0603 M&Ms – Mantle Melting – Measurements, Models, Mechanisms) to JBT is gratefully acknowledged.

Editor: Bruce Watson

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References

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Supplementary Information

Geologic Setting, Analytical Details, and Isotopic Measurements

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Timpe Santa Caterina clinopyroxene phenocrysts (typically at least 1 mm, shortest dimension) were handpicked, mounted in epoxy, and polished to 0.3 µm. Trace element concentrations were collected by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) using a Nu AttoM high resolution spectrometer and New Wave UP213 (213 nm) deep-UV YAG laser ablation system at the University of New Hampshire with a ~40 μm diameter laser spot size. Samples were lightly polished to remove any sputtered debris and major element compositions near the laser pits were then analysed by electron microprobe at the University of Oregon. Major and trace element data, additional analytical details, and uncertainties are reported below (Tables S-1, S-2, and S-3). Additional cpx major element data (Table S-4) not associated with LA-ICP-MS measurements but used for thermobarometry were collected at the Massachusetts Institute of Technology (MIT).

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	TSC2_G1_1	1 σ		TSC2_G1_2	1 σ		TSC2_G1_4	1 σ		TSC2_G3_2	1 σ		TSC2_G3_3	1 σ
SiO2	46.19	0.10		46.07	0.10		47.40	0.15		49.74	0.10		49.77	0.10
TiO2	1.78	0.03		1.96	0.03		2.02	0.01		0.95	0.02		0.94	0.02
Al2O3	7.08	0.04		7.46	0.04		7.67	0.03		3.78	0.03		4.06	0.03
FeO	8.70	0.16		9.22	0.16		8.99	0.04		8.23	0.15		7.85	0.15
MnO	0.13	0.01		0.15	0.01		0.17	0.01		0.17	0.01		0.18	0.01
MgO	12.76	0.05		12.53	0.05		11.96	0.05		14.71	0.06		14.43	0.06
CaO	21.19	0.07		20.93	0.07		20.87	0.15		20.98	0.07		21.32	0.07
Na2O	0.59	0.03		0.57	0.03		0.49	0.02		0.54	0.03		0.45	0.03
K2O	0.01	0.01		0.00	0.01		0.01	0.01		0.01	0.01		0.01	0.01
Cr2O3	0.00	0.03		0.02	0.03		0.04	0.01		0.04	0.03		0.00	0.03
TOTAL	98.43			98.91			99.62			99.14			98.99
	TSC2_G3_4	1 σ		TSC2_G3_5	1 σ		TSC2_G3_6	1 σ		TSC2_G4_1	1 σ		TSC2_G2_1	1 σ
SiO2	48.41	0.10		48.81	0.10		48.21	0.10		48.03	0.10		47.13	0.10
TiO2	1.30	0.02		1.47	0.02		2.02	0.03		1.40	0.02		1.64	0.02
Al2O3	5.50	0.04		4.87	0.03		5.81	0.04		6.99	0.04		6.38	0.04
FeO	8.65	0.16		7.79	0.15		8.33	0.15		7.06	0.14		8.62	0.16
MnO	0.14	0.01		0.16	0.01		0.17	0.01		0.06	0.01		0.14	0.01
MgO	13.58	0.06		13.80	0.06		13.07	0.05		13.40	0.06		13.00	0.05
CaO	21.03	0.07		21.16	0.07		21.19	0.07		21.99	0.07		21.36	0.07
Na2O	0.56	0.03		0.58	0.03		0.52	0.03		0.40	0.03		0.74	0.04
K2O	0.01	0.01		0.00	0.01		0.00	0.01		0.01	0.01		0.00	0.01
Cr2O3	0.00	0.03		0.01	0.03		0.00	0.00		0.14	0.03		0.01	0.03
TOTAL	99.18			98.65			99.31			99.49			99.02
	TSC2_G2_2	1 σ		TSC2_G2_3	1 σ		TSC2_G8_1	1 σ		TSC2_G8_2	1 σ		TSC7_G2_1	1 σ
SiO2	47.51	0.10		48.04	0.10		47.34	0.10		47.47	0.10		47.37	0.10
TiO2	1.42	0.02		1.47	0.02		1.63	0.02		1.68	0.03		1.86	0.03
Al2O3	6.65	0.04		6.73	0.04		6.42	0.04		6.37	0.04		7.16	0.04
FeO	8.23	0.15		8.11	0.15		8.62	0.16		8.33	0.15		7.83	0.15
MnO	0.12	0.01		0.13	0.01		0.15	0.01		0.14	0.01		0.12	0.01
MgO	13.18	0.06		13.20	0.06		12.61	0.05		12.47	0.05		12.83	0.05
CaO	21.50	0.07		21.19	0.07		21.16	0.07		21.08	0.07		21.71	0.07
Na2O	0.58	0.03		0.59	0.03		0.56	0.03		0.62	0.03		0.55	0.03
K2O	0.01	0.01		0.00	0.01		0.01	0.01		0.00	0.00		0.00	0.01
Cr2O3	0.02	0.03		0.01	0.03		0.02	0.03		0.00	0.03		0.01	0.03
TOTAL	99.22			99.47			98.51			98.15			99.43
	TSC7_G5_1	1 σ		TSC7_G7_1	1 σ		TSC7_G9_1	1 σ		TSC7_G10_1	1 σ		TSC7_G10_2	1 σ
SiO2	46.86	0.10		48.29	0.10		46.40	0.10		48.66	0.10		48.80	0.10
TiO2	1.87	0.03		1.73	0.03		1.75	0.03		1.78	0.03		1.17	0.02
Al2O3	6.31	0.04		5.37	0.04		7.34	0.04		4.81	0.03		5.54	0.04
FeO	7.83	0.15		7.95	0.15		6.65	0.14		7.84	0.15		5.69	0.13
MnO	0.13	0.01		0.14	0.01		0.10	0.01		0.14	0.01		0.07	0.01
MgO	12.90	0.05		13.29	0.06		13.14	0.05		13.24	0.06		14.41	0.06
CaO	22.19	0.07		21.70	0.07		22.78	0.07		21.89	0.07		23.04	0.07
Na2O	0.53	0.03		0.56	0.03		0.43	0.03		0.46	0.03		0.34	0.03
K2O	0.01	0.01		0.00	0.01		0.00	0.01		0.00	0.01		0.00	0.01
Cr2O3	0.00	0.03		0.00	0.03		0.00	0.03		0.04	0.03		0.13	0.03
TOTAL	98.63			99.04			98.59			98.85			99.18
	TSC7_G10_3	1 σ		TSC7_G10_4	1 σ		TSC7_G10_5	1 σ		TSC7_G10_6	1 σ		TSC3_G1_1	1 σ
SiO2	48.24	0.10		49.07	0.10		49.50	0.10		49.48	0.10		48.68	0.10
TiO2	1.19	0.02		0.99	0.02		0.94	0.02		1.34	0.02		1.56	0.02
Al2O3	5.40	0.04		5.05	0.03		4.82	0.03		3.95	0.03		4.89	0.03
FeO	5.55	0.13		5.38	0.12		5.42	0.13		7.90	0.15		7.47	0.15
MnO	0.07	0.01		0.07	0.01		0.06	0.01		0.15	0.01		0.16	0.01
MgO	14.20	0.06		14.54	0.06		14.96	0.06		14.11	0.06		13.43	0.06
CaO	22.91	0.07		22.77	0.07		22.78	0.07		22.15	0.07		21.92	0.07
Na2O	0.33	0.03		0.38	0.03		0.36	0.03		0.39	0.03		0.46	0.03
K2O	0.00	0.01		0.00	0.01		0.00	0.01		0.00	0.01		0.00	0.01
Cr2O3	0.10	0.03		0.25	0.04		0.27	0.04		0.06	0.03		0.02	0.03
TOTAL	97.99			98.50			99.12			99.52			98.59
	TSC3_G1_2	1 σ		TSC3_G1_3	1 σ		TSC3_G3_1	1 σ		TSC3_G3_2	1 σ		TSC3_G3_3	1 σ
SiO2	45.12	0.10		46.57	0.10		49.08	0.10		48.10	0.10		49.31	0.10
TiO2	2.51	0.03		2.19	0.03		1.52	0.02		1.56	0.02		1.41	0.02
Al2O3	7.87	0.04		6.86	0.04		5.45	0.04		5.15	0.03		4.26	0.03
FeO	8.34	0.15		8.19	0.15		8.53	0.16		7.71	0.15		7.61	0.15
MnO	0.14	0.01		0.15	0.01		0.19	0.01		0.17	0.01		0.17	0.01
MgO	11.79	0.05		12.35	0.05		13.37	0.06		13.58	0.06		14.03	0.06
CaO	22.01	0.07		22.16	0.07		21.03	0.07		22.24	0.07		22.18	0.07
Na2O	0.45	0.03		0.51	0.03		0.64	0.03		0.54	0.03		0.48	0.03
K2O	0.02	0.01		0.00	0.01		0.01	0.01		0.00	0.01		0.00	0.01
Cr2O3	0.00	0.03		0.01	0.03		0.02	0.03		0.01	0.03		0.00	0.03
TOTAL	98.26			98.99			99.85			99.05			99.47
	TSC3_G9_1	1 σ		TSC3_G9_3	1 σ		TSC3_G9_4	1 σ		TSC9_G1_1	1 σ		TSC9_G1_2	1 σ
SiO2	49.35	0.10		49.34	0.10		47.90	0.10		48.32	0.10		47.92	0.10
TiO2	1.59	0.02		1.32	0.02		1.95	0.03		1.25	0.02		1.69	0.03
Al2O3	5.20	0.04		4.43	0.03		6.23	0.04		6.29	0.04		5.82	0.04
FeO	8.36	0.15		7.61	0.15		8.18	0.15		8.43	0.15		7.21	0.14
MnO	0.16	0.01		0.15	0.01		0.15	0.01		0.14	0.01		0.11	0.01
MgO	13.43	0.06		14.10	0.06		12.90	0.05		13.00	0.05		13.25	0.06
CaO	22.26	0.07		22.56	0.07		21.80	0.07		22.06	0.07		22.00	0.07
Na2O	0.57	0.03		0.37	0.03		0.48	0.03		0.43	0.03		0.44	0.03
K2O	0.00	0.01		0.00	0.01		0.01	0.01		0.01	0.01		0.01	0.01
Cr2O3	0.05	0.03		0.00	0.03		0.02	0.03		0.00	0.03		0.00	0.03
TOTAL	100.96			99.87			99.62			99.93			98.45
	TSC9_G3_1	1 σ		TSC9_G3_2	1 σ		TSC9_G5_1	1 σ
SiO2	47.39	0.10		48.74	0.10		47.55	0.10
TiO2	1.97	0.03		1.63	0.02		1.63	0.03
Al2O3	5.61	0.04		5.29	0.04		4.87	0.03
FeO	7.52	0.15		7.27	0.14		7.66	0.15
MnO	0.14	0.01		0.13	0.01		0.17	0.01
MgO	13.19	0.06		13.60	0.06		13.44	0.06
CaO	22.33	0.07		22.16	0.07		22.48	0.07
Na2O	0.56	0.03		0.53	0.03		0.46	0.03
K2O	0.02	0.01		0.02	0.01		0.01	0.01
Cr2O3	0.01	0.03		0.00	0.03		0.04	0.03
TOTAL	98.74			99.36			98.31

* TSC samples were collected from a cliff below Via Pianetto at 37°36’21” N and 15°10’20” E from the base at sea level to the top, approximately 85 m above, as shown in the cross section of Figure S-1.

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	TSC2_G1_1	1 s.e.		TSC2_G1_2	1 s.e.		TSC2_G1_3	1 s.e.		TSC2_G1_4	1 s.e.		TSC2_G3_1	1 s.e.
Li	50	7		103	14		55	8		60	8		54	7
Sc	105	3		91	3		97	3		97	3		98	3
Ti	10307	233		8896	154		9244	187		10272	294		5911	98
V	317	13		257	11		318	14		327	15		224	10
Cr	66	3		59	2		60	3		51	3		24	2
Ni	68	7		58	6		62	6		38	3		51	4
Sr	132	7		124	6		116	6		128	8		132	7
Y	54	1		45	1		42	1		46	2		38	1
Zr	128	4		107	4		99	4		114	6		75	3
Nb	0.9	0.3		1.6	0.2		0.89	0.2		1.0	0.2		0.6	0.1
Sn	2.3	0.3		1.0	0.3		1.8	0.2		4.2	0.3		1.6	0.4
La	15	1		12.0	0.9		11.2	0.7		14	1		11.0	0.8
Ce	48	4		42	3		37	3		48	4		39	3
Pr	9.3	0.9		7.9	0.8		7.2	0.7		9	1		7.1	0.7
Nd	49	4		43	3		38	3		45	3		38	3
Sm	14.0	0.7		12	1		11.0	0.5		12.2	0.7		9.6	0.4
Eu	4.5	0.5		4.0	0.4		3.3	0.3		4.6	0.4		3.5	0.3
Gd	15	2		15	1		12	1		13	2		10.0	0.8
Tb	2.3	0.2		2.2	0.2		1.5	0.1		1.8	0.2		1.8	0.1
Dy	14.0	0.5		10	1		9.7	0.6		12	1		10.4	0.5
Ho	2.5	0.1		2.25	0.2		2.0	0.1		1.9	0.1		1.9	0.1
Er	7.7	0.7		5.1	0.6		5.0	0.5		5.4	0.7		4.4	0.6
Tm	0.88	0.07		0.62	0.09		0.72	0.02		0.5	0.1		0.60	0.02
Yb	3.6	0.4		3.9	0.3		3.9	0.3		3.2	0.5		2.6	0.3
Lu	0.49	0.07		0.6	0.1		0.45	0.09		0.5	0.2		0.4	0.1
Hf	8.2	0.8		7.4	0.5		5.0	0.6		8	1		4.7	0.5
Pb	0.14	0.03		0.17	0.03		0.19	0.03		0.4	0.3		0.21	0.05
Th	0.29	0.03		0.20	0.03		0.19	0.03		0.25	0.03		0.13	0.02
U	0.025	0.009		0.029	0.008		0.038	0.010		0.002	0.009		0.008	0.008
	TSC2_G3_2	1 s.e.		TSC2_G3_3	1 s.e.		TSC2_G3_4	1 s.e.		TSC2_G3_5	1 s.e.		TSC2_G3_6	1 s.e.
Li	14	2		5.4	0.7		14	2		9	1		16	2
Sc	113	3		106	3		96	8		90	2		89	3
Ti	4888	85		4772	102		5551	390		6382	173		6255	125
V	218	9		234	10		249	19		273	14		269	11
Cr	24	1		30	1		32	3		46	2		42	2
Ni	41	3		37	4		38	3		42	3		39	3
Sr	84	4		77	4		74	6		82	4		86	4
Y	21.6	0.6		20.2	0.6		18	2		20.4	0.7		20	0.6
Zr	47	2		40	2		38	2		44	2		44	2
Nb	0.36	0.06		0.41	0.08		0.29	0.08		0.59	0.09		0.8	0.1
Sn	0.5	0.1		0.5	0.2		0.7	0.2		0.7	0.2		0.7	0.1
La	5.1	0.4		4.3	0.3		4.2	0.4		4.6	0.3		5.1	0.3
Ce	18	1		16	1		14	2		18	1		18	1
Pr	3.6	0.4		3.3	0.3		3	0.4		3.3	0.3		3.7	0.4
Nd	21	2		16	2		16	1		16	1		20	1
Sm	5.1	0.3		4.3	0.2		4.2	0.7		3.9	0.1		3.8	0.2
Eu	1.4	0.2		1.4	0.1		1.2	0.1		1.2	0.1		1.4	0.2
Gd	6.7	0.8		4.8	0.4		4	0.8		4.9	0.4		5.8	0.5
Tb	1.1	0.1		0.9	0.1		1	0.1		0.96	0.06		1	0.1
Dy	4.9	0.2		4.4	0.2		3.4	0.6		3.9	0.3		4.7	0.4
Ho	0.74	0.06		0.69	0.07		0.63	0.02		0.75	0.05		0.59	0.03
Er	2.3	0.3		1.9	0.2		1.6	0.4		1.6	0.2		1.9	0.2
Tm	0.29	0.05		0.28	0.02		0.28	0.06		0.34	0.05		0.33	0.04
Yb	1.8	0.1		1.4	0.2		1.8	0.2		1.1	0.2		1	0.2
Lu	0.22	0.05		0.23	0.04		0.19	0.03		0.19	0.03		0.22	0.03
Hf	1.6	0.2		1.4	0.1		1.4	0.2		1.4	0.2		1.4	0.2
Pb	0.068	0.008		0.13	0.03		0.08	0.02		0.13	0.02		0.14	0.04
Th	0.050	0.008		0.045	0.006		0.05	0.01		0.05	0.01		0.11	0.01
U	0.007	0.003		0.007	0.002		0.013	0.002		0.009	0.002		0.016	0.002
	TSC2_G4_1	1 s.e.		TSC2_G4_2	1 s.e.		TSC2_G2_1	1 s.e.		TSC2_G2_2	1 s.e.		TSC2_G2_3	1 s.e.
Li	53	7		59	8		18	3		46	6		28	4
Sc	131	4		129	5		117	3		105	3		139	6
Ti	6293	115		6055	128		8882	153		6910	140		8867	314
V	275	11		279	12		314	14		288	12		332	17
Cr	642	23		640	27		42	3		54	3		44	3
Ni	106	7		107	7		52	4		68	4		39	3
Sr	99	5		84	4		112	6		95	5		89	5
Y	18	1		17	0.6		41	1		36	2		38	2
Zr	34	2		30	1		84	3		102	7		81	4
Nb	0.42	0.08		0.1	0.1		0.6	0.1		4.7	0.5		1.1	0.2
Sn	0.5	0.2		0.5	0.2		1.6	0.2		0.8	0.2		1.2	0.3
La	4.1	0.3		3.2	0.2		11.4	0.7		22	2		10.1	0.8
Ce	13	1		10.9	0.9		35	3		53	5		31	3
Pr	2.5	0.3		2.2	0.3		6.6	0.7		8	1		6	0.6
Nd	13	1		12	1		38	3		37	4		32	2
Sm	3.6	0.5		3.1	0.2		10.4	0.9		8.8	0.8		9.5	0.2
Eu	1.5	0.2		1	0.1		3.1	0.3		2.4	0.3		2.7	0.3
Gd	5	0.7		5.3	0.8		13	1		10	1		10	1
Tb	0.7	0.1		0.56	0.09		1.6	0.1		1.4	0.1		1.3	0.1
Dy	3.3	0.1		4	0.4		8.2	0.6		7.9	0.3		7.5	0.4
Ho	1	0.04		0.61	0.03		1.5	0.1		1.4	0.1		1.4	0.1
Er	1.1	0.3		1.7	0.3		4.8	0.4		4.3	0.5		3.3	0.4
Tm	0.27	0.07		0.23	0.07		0.55	0.06		0.6	0.1		0.34	0.04
Yb	1.3	0.2		0.6	0.3		3.5	0.2		3.1	0.3		2.4	0.4
Lu	0.32	0.04		0.21	0.09		0.54	0.09		0.7	0.1		0.35	0.06
Hf	1.1	0.2		1.3	0.1		4.2	0.4		3.3	0.5		3.4	0.3
Pb	0.03	0.02		0.09	0.03		0.08	0.02		1.4	0.19		0.11	0.04
Th	0.062	0.005		0.04	0.01		0.2	0.01		1.8	0.2		0.19	0.02
U	0.007	0.002		0.006	0.003		0.018	0.004		0.19	0.03		0.024	0.004
	TSC2_G8_1	1 s.e.		TSC2_G8_2	1 s.e.		TSC7_G2_1	1 s.e.		TSC7_G2_2	1 s.e.		TSC7_G5_1	1 s.e.
Li	10	1		34	5		21	3		5.8	0.8		2.7	0.4
Sc	101	3		107	4		107	3		100	3		127	5
Ti	8210	151		8450	374		10814	216		9617	196		9624	290
V	302	13		306	18		314	14		321	13		265	12
Cr	52	2		48	2		76	6		68	3		360	39
Ni	46	4		44	3		57	4		46	3		56	6
Sr	85	5		76	5		138	7		115	6		113	7
Y	27	1		25	2		36	1		37	2		28	1
Zr	62	3		62	3		94	3		95	3		79	5
Nb	0.4	0.1		0.7	0.1		1.4	0.2		0.6	0.1		0.7	0.2
Sn	0.8	0.2		0.6	0.2		1.6	0.3		1.2	0.1		2.7	0.6
La	6.9	0.4		6.5	0.5		9.2	0.7		9.1	0.6		6.3	0.7
Ce	24	5		21	2		31	2		35	3		24	2
Pr	4.5	0.5		4.5	0.5		6	0.6		6.8	0.7		4.6	0.5
Nd	21	2		21	2		32	3		36	3		28	2
Sm	7.3	0.5		6.1	0.4		9.2	0.9		9.2	0.6		6.3	0.3
Eu	2.1	0.2		1.6	0.2		3	0.5		3.6	0.4		2.7	0.3
Gd	6.9	0.9		5.9	0.7		10.7	0.8		8.4	0.7		6.4	0.8
Tb	1	0.1		0.91	0.06		1.6	0.1		1.5	0.1		1.23	0.09
Dy	5.9	0.5		5.6	0.2		6.5	0.4		7.2	0.4		6.2	0.3
Ho	0.83	0.08		0.83	0.08		1.7	0.2		1.7	0.1		1.2	0.1
Er	3.3	0.6		3.6	0.5		4.4	0.8		3.4	0.4		2.6	0.5
Tm	0.24	0.03		0.24	0.03		0.46	0.09		0.51	0.03		0.27	0.08
Yb	2	0.2		1.9	0.2		2.8	0.2		2.5	0.3		1.5	0.3
Lu	0.27	0.08		0.24	0.05		0.4	0.1		0.32	0.05		0.29	0.06
Hf	2.7	0.2		3.1	0.3		3.4	0.4		3.9	0.3		3.9	0.4
Pb	0.08	0.02		0.05	0.02		0.12	0.05		0.13	0.02		0.1	0.03
Th	0.12	0.02		0.09	0.01		0.15	0.03		0.15	0.02		0.079	0.008
U	0.018	0.006		0.017	0.006		0.019	0.006		0.016	0.006		0.007	0.003
	TSC7_G7_1	1 s.e.		TSC7_G9_1	1 s.e.		TSC7_G10_1	1 s.e.		TSC7_G10_2	1 s.e.		TSC7_G10_3	1 s.e.
Li	5.1	0.7		3.8	0.6		6.9	0.9		4.3	0.6		5.4	0.8
Sc	145	5		125	4		133	3		134	3		143	4
Ti	11294	172		9592	192		8341	236		6522	169		6252	113
V	343	14		298	13		325	15		240	11		239	10
Cr	44	2		109	4		751	38		1005	46		824	39
Ni	49	4		88	6		50	6		90	5		87	5
Sr	136	7		137	8		80	4		68	3		68	4
Y	47	1		23	1		23	1		10	0		10	0
Zr	137	5		56	3		73	3		24	1		23	1
Nb	1.5	0.1		0.53	0.09		0.7	0.1		0.09	0.07		0.13	0.04
Sn	2.1	0.4		2.4	0.4		0.5	0.2		0.6	0.2		0.54	0.07
La	15	1		5.5	0.4		6.2	0.5		1.8	0.2		1.6	0.1
Ce	48	4		20	2		23	2		7	0.6		6.8	0.5
Pr	9.1	0.9		3.9	0.4		4.3	0.4		1.5	0.2		1.4	0.1
Nd	48	4		23	2		23	2		7.8	0.8		8.1	0.6
Sm	12.5	0.4		5.6	0.4		5.6	0.6		2.6	0.3		2.7	0.3
Eu	4.3	0.4		2	0.3		1.6	0.1		0.81	0.09		0.8	0.07
Gd	11.5	0.9		5.9	0.8		6.8	0.6		2.5	0.3		2.4	0.3
Tb	1.9	0.2		1.11	0.09		1	0.1		0.51	0.05		0.48	0.07
Dy	10.2	0.7		4.9	0.6		4.1	0.2		2.5	0.3		1.88	0.06
Ho	2.6	0.3		1.2	0.1		0.8	0.03		0.31	0.02		0.35	0.03
Er	4.3	0.5		2.7	0.3		2.5	0.3		0.81	0.09		0.9	0.1
Tm	0.76	0.06		0.18	0.04		0.25	0.04		0.12	0.03		0.12	0.01
Yb	3.3	0.5		1.4	0.1		1.9	0.3		0.7	0.2		0.9	0.1
Lu	0.49	0.14		0.33	0.06		0.33	0.04		0.05	0.04		0.13	0.04
Hf	5.9	0.6		2.5	0.3		3.9	0.3		1.6	0.2		1.5	0.1
Pb	0.16	0.03		0.06	0.01		0.08	0.02		0.025	0.003		0.05	0.02
Th	0.25	0.03		0.08	0.02		0.08	0.01		0.02	0.01		0.03	0.008
U	0.021	0.003		0.017	0.006		0.011	0.004		nd			0.004	0.003
	TSC7_G10_4	1 s.e.		TSC7_G10_5	1 s.e.		TSC7_G10_6	1 s.e.		TSC3_G1_1	1 s.e.		TSC3_G1_2	1 s.e.
Li	3.3	0.5		2.4	0.4		3	0.4		2.6	0.6		1.3	0.3
Sc	131	4		131	5		144	5		81	2		91	3
Ti	5276	143		5415	101		7483	175		7430	159		10948	178
V	210	12		221	9		282	12		173	8		218	9
Cr	2332	116		1363	59		69	3		19	1		15	1
Ni	93	5		89	5		36	2		24	4		26	2
Sr	64	3		62	3		76	4		188	10		196	10
Y	9	1		9	0		19	1		36	1		40	1
Zr	19	1		20	1		52	2		135	4		193	5
Nb	0.18	0.02		0.15	0.05		0.34	0.03		1	0.1		2.1	0.2
Sn	0.42	0.05		0.36	0.06		0.8	0.1		1.7	0.3		2.2	0.4
La	1.6	0.1		1.47	0.09		4.4	0.3		17	1		24	1
Ce	6.2	0.5		5.6	0.5		16	1		50	4		67	5
Pr	1.3	0.2		1.2	0.1		3.2	0.3		11	1		14	1
Nd	7.2	0.6		7.1	0.7		19	1		57	5		72	5
Sm	2.4	0.6		2.4	0.2		4.4	0.3		10.6	0.5		14	0.7
Eu	0.77	0.06		0.7	0.1		1.5	0.2		4.2	0.4		5.1	0.6
Gd	1.9	0.2		2.8	0.2		5.5	0.6		16	1		18	2
Tb	0.24	0.03		0.46	0.03		0.71	0.07		1.9	0.2		1.8	0.2
Dy	1.7	0.1		1.81	0.3		4.2	0.1		9.8	0.4		10	0.6
Ho	0.29	0.04		0.29	0.03		0.76	0.04		1.7	0.2		1.72	0.08
Er	1	0.1		0.7	0.1		2.3	0.2		2.9	0.3		3.7	0.5
Tm	0.09	0.02		0.1	0.04		0.18	0.03		0.53	0.05		0.6	0.1
Yb	0.49	0.08		0.5	0.03		1.8	0.3		3.1	0.4		2.2	0.6
Lu	0.08	0.01		0.07	0.02		0.19	0.05		0.4	0.06		0.5	0.1
Hf	0.9	0.1		1.3	0.2		2.3	0.3		5.4	0.4		7.4	0.6
Pb	0.03	0.01		0.03	0.01		0.04	0.01		0.11	0.02		0.08	0.01
Th	0.015	0.004		0.027	0.006		0.053	0.006		0.21	0.01		0.42	0.06
U	0.003	0.002		0.003	0.001		0.008	0.001		0.021	0.005		0.045	0.006
	TSC3_G1_3	1 s.e.		TSC3_G3_1	1 s.e.		TSC3_G3_2	1 s.e.		TSC3_G3_3	1 s.e.		TSC3_G9_1	1 s.e.
Li	3.4	0.6		4.5	0.7		1	0.3		0.9	0.2		6.6	1
Sc	93	3		60	2		84	3		101	3		113	4
Ti	10122	201		7869	133		7534	145		6712	123		8850	302
V	213	18		195	8		186	8		194	9		268	12
Cr	9.5	0.8		11.6	0.5		10.3	0.8		10	1		11.5	0.7
Ni	21	3		21	2		17	1		14	2		18	3
Sr	255	19		163	8		157	8		149	8		181	12
Y	40	1		31.7	0.8		29.6	0.7		29	1		37.9	0.9
Zr	186	6		114	4		109	3		114	4		183	6
Nb	5.4	0.8		1.1	0.1		0.76	0.07		0.9	0.1		1.8	0.1
Sn	1.7	0.4		0.9	0.2		0.7	0.3		0.6	0.2		0.8	0.2
La	26	2		15.5	0.9		14.2	0.9		13.5	0.8		19	1
Ce	68	6		45	3		42	3		40	3		64	6
Pr	13	1		9	1		9	1		8.3	0.8		12	1
Nd	66	5		48	4		43	3		38	3		53	4
Sm	13.7	0.7		11	1		10	1		9.7	0.6		12.8	0.6
Eu	3.9	0.3		4	0		3	0		3.1	0.3		3.4	0.3
Gd	17	2		12	1		12	1		9.9	0.8		13	1
Tb	1.6	0.2		1.6	0.2		1.4	0.2		1.3	0.1		1.8	0.1
Dy	9.6	0.7		7.4	0.4		6.1	0.3		5.5	0.4		9	0.5
Ho	1.4	0.05		1.48	0.08		1.07	0.07		1.1	0.08		1.4	0.1
Er	3.1	0.5		2.9	0.4		2.7	0.4		3.2	0.4		4.3	0.6
Tm	0.54	0.05		0.39	0.08		0.29	0.04		0.4	0.06		0.38	0.07
Yb	2.5	0.5		2.8	0.5		2.2	0.3		2.8	0.6		2.3	0.1
Lu	0.29	0.07		0.34	0.07		0.38	0.08		0.31	0.08		0.4	0.06
Hf	7.3	0.7		4.2	0.3		4.4	0.4		4.3	0.3		6.8	0.7
Pb	0.9	0.2		0.07	0.01		0.11	0.01		0.04	0.01		0.16	0.03
Th	1.2	0.2		0.23	0.03		0.15	0.01		0.17	0.02		0.35	0.04
U	0.32	0.06		0.021	0.004		0.011	0.003		0.023	0.003		0.062	0.008
	TSC3_G9_3	1 s.e.		TSC3_G9_4	1 s.e.		TSC9_G1_1	1 s.e.		TSC9_G1_2	1 s.e.		TSC9_G3_1	1 s.e.
Li	0.3	0.3		1.3	0.2		36	5		33	5		28	4
Sc	105	4		88	2		53	1		78	2		114	3
Ti	9521	375		9280	198		5875	95		8005	159		10648	166
V	278	14		242	10		227	10		263	13		216	9
Cr	21	2		13.9	0.7		36	3		42	2		23	1
Ni	32	2		23	3		37	2		35	4		22	2
Sr	154	8		168	9		123	8		116	7		150	7
Y	25.8	0.8		30.8	0.9		15.6	0.4		21.4	0.8		31.1	0.9
Zr	108	4		130	4		49	1		67	2		142	4
Nb	1.4	0.2		1.2	0.2		0.5	0.1		0.61	0.07		1.1	0.1
Sn	1.1	0.2		0.8	0.2		0.53	0.06		1	0.2		1.6	0.2
La	12.2	0.8		14.8	0.9		6	0.4		8	0.5		14.5	0.9
Ce	41	3		50	4		24	2		31	3		48	4
Pr	8.1	0.8		10	1		4.2	0.4		5.6	0.6		8.7	0.9
Nd	36	3		44	3		21	2		28	2		46	3
Sm	9.2	0.4		11	1		5.8	0.5		7.6	0.5		11.6	0.4
Eu	2.9	0.2		3.4	0.3		1.7	0.2		2.6	0.4		3.2	0.3
Gd	8.7	0.9		9.8	0.8		4.6	0.5		6.7	0.9		10.7	0.9
Tb	1.17	0.08		1.3	0.1		0.68	0.09		0.91	0.06		1.3	0.1
Dy	5	0.1		6.6	0.3		3.7	0.5		5.6	0.4		7.4	0.4
Ho	0.99	0.06		1.1	0.1		0.83	0.02		1.13	0.09		1.6	0.1
Er	3.3	0.3		2.8	0.5		1.7	0.3		2.3	0.2		3.6	0.4
Tm	0.39	0.06		0.42	0.03		0.21	0.02		0.24	0.03		0.28	0.02
Yb	1.8	0.3		2.5	0.2		1.2	0.2		1.25	0.05		2	0.4
Lu	0.29	0.08		0.37	0.05		0.07	0.02		0.18	0.02		0.29	0.04
Hf	3.7	0.2		4.4	0.4		2.2	0.2		3	0.2		6.3	0.4
Pb	0.04	0.01		0.05	0.01		0.04	0.02		0.04	0.02		0.1	0.01
Th	0.19	0.01		0.19	0.02		0.088	0.006		0.1	0.02		0.2	0.01
U	0.017	0.007		0.021	0.005		0.017	0.004		0.019	0.005		0.025	0.003
	TSC9_G3_2	1 s.e.		TSC9_G5_1	1 s.e.		TSC9_G5_2	1 s.e.
Li	24	3		18	3		10	1
Sc	99	2		99	5		114	3
Ti	8647	135		9205	538		10315	165
V	184	8		255	14		271	12
Cr	21	1		24	3		7	1
Ni	26	2		27	4		18	2
Sr	146	7		151	14		184	9
Y	24.5	0.9		24	1		40	1
Zr	94	3		98	7		158	6
Nb	0.82	0.07		0.8	0.1		1.8	0.2
Sn	1.2	0.2		1.1	0.2		1.4	0.4
La	10.3	0.6		14	1		24	1
Ce	35	3		53	5		87	7
Pr	6.3	0.6		8	0.8		14	1
Nd	35	3		39	3		64	5
Sm	9.2	0.4		9	1		16	1
Eu	2.3	0.2		2.6	0.2		5	0
Gd	8.4	0.9		8	1		15	1
Tb	1	0.1		1.04	0.07		2	0
Dy	6.1	0.3		5.5	0.4		10.3	0.5
Ho	0.9	0.1		0.99	0.08		1.5	0.07
Er	2.4	0.3		2.5	0.4		3.7	0.3
Tm	0.3	0.05		0.29	0.06		0.39	0.04
Yb	1.3	0.2		1.7	0.2		3.2	0.2
Lu	0.26	0.04		0.16	0.03		0.44	0.06
Hf	3.8	0.2		4.5	0.5		6.8	0.4
Pb	0.05	0.01		0.22	0.05		0.14	0.03
Th	0.117	0.008		0.18	0.03		0.23	0.02
U	0.034	0.005		0.033	0.008		0.04	0.005

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Trace element analytical methods
Trace element concentrations of TSC clinopyroxenes were collected by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) using a Nu AttoM high resolution spectrometer and New Wave UP213 (213 nm) deep-UV YAG laser ablation system at the University of New Hampshire. Laser spots on sample material were ~40 μm in diameter.

The concentration of trace element i in the clinopyroxene sample, (C_i^sample), reported in ppm, was calculated using the following relationship:

Calcium concentrations (C_Ca^sample), measured near each laser ablation pit by electron microprobe, served as the internal reference element. I represents the background corrected signal intensity of a material and R denotes the reference standard glass, ML3B-G. Trace element signal intensities were calculated from LA-ICP-MS measurements via the following processing procedure: an ablation interval of typically 12–15 peak count cycles was corrected for background by subtracting a background count average (typically of 24 background cycles, with half taken before sample count collection and half after) from each cycle collected within the ablation interval (the sample peak). The median of either four or five sub-intervals within the ablation interval was used to represent the background corrected sample count value (I_i^sample). ML3B-G glass served as the reference standard and two ML3B-G points were measured between every set of five unknowns. Background corrected count values for the ML3B-G glass standard (I_i^R) were collected in the same manner. Concentrations at each sample location were calculated using the reference standard signals collected closest in time to the sample measurement over the course of the analyses.

The error propagated for each analysis consisted of the standard error (s.e.) of the mean for the subintervals of sample peak selected, the uncertainty of internal standard electron microprobe Ca measurement, and the uncertainty of the calibration standard ML3B-G measurements, which was taken as the difference between the reported ML3B-G concentrations (Jochum et al., 2006) and the average of repeat analyses of ML3B-G over the course of the TSC clinopyroxene measurements reported in this study.

	ML3B-G*	LA-ICP-MS
	literature value	average
	ppm	ppm	Δ lit-avg	Δ as %	1 σ*	1 σ as %
Li	4.50	5.20	0.70	15.5	0.93	21
Sc	31.60	31.01	-0.59	-1.9	1.30	4
Ti	12769.78	12823.95	54.16	0.4	368.34	3
V	268.00	278.64	10.64	4.0	17.92	7
Cr	177.00	182.94	5.94	3.4	9.81	6
Ni	107.00	112.63	5.63	5.3	6.76	6
Sr	312.00	327.32	15.32	4.9	21.96	7
Y	23.90	24.29	0.39	1.6	1.85	8
Zr	122.00	124.98	2.98	2.4	8.76	7
Nb	8.61	9.17	0.56	6.5	0.93	11
Sn	1.14	1.16	0.02	1.4	0.38	33
La	8.99	9.53	0.54	6.0	0.97	11
Ce	23.10	24.95	1.85	8.0	2.69	12
Pr	3.43	3.80	0.37	10.7	0.49	14
Nd	16.70	17.95	1.25	7.5	2.22	13
Sm	4.75	4.79	0.04	0.8	0.73	15
Eu	1.67	1.81	0.14	8.6	0.21	12
Gd	5.26	5.67	0.41	7.8	0.92	17
Tb	0.80	0.84	0.04	5.5	0.18	23
Dy	4.84	4.85	0.01	0.2	0.58	12
Ho	0.91	0.91	0.00	0.5	0.13	14
Er	2.44	2.64	0.20	8.4	0.41	17
Tm	0.32	0.33	0.00	1.5	0.06	20
Yb	2.06	2.00	-0.06	-2.7	0.45	22
Lu	0.29	0.32	0.04	13.2	0.08	28
Hf	3.22	3.42	0.20	6.2	0.76	24
Pb	1.38	1.53	0.15	10.5	0.23	17
Th	0.55	0.57	0.02	4.5	0.06	11
U	0.44	0.50	0.05	12.2	0.09	20

* ML3B-G was analysed twice between every 5 unknown samples, totalling 24 standard analyses during collection of the TSC data reported in this study. Analytical uncertainty is determined by having the first of each two ML3B-G analyses serve as the 'standard' for calculating the concentration of the second ML3B-G analysis, which is run as an unknown sample. The average value of the 12 ML3B-G 'unknowns' is compared here with the literature values for these trace elements (Jochum et al., 2006) along with the standard deviation of these ML3B-G runs.

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	SiO2	TiO2	Al2O3	FeOt†	MnO	MgO	CaO	Na2O	K2O	Cr2O3	Total
TSC-2A-2	47.74	1.41	6.8	7.17	0.11	13.09	21.8	0.3	0.01	0.01	98.44
TSC-2A-3	48.57	1.3	6.49	7.95	0.13	12.82	21.42	0.4	0	0.04	99.12
TSC-2A-4	47.88	1.29	6.4	7.71	0.13	13.22	21.28	0.36	0	0.04	98.31
TSC-2A-5	48.71	1.23	6.17	7.94	0.15	13.44	21.44	0.44	0	0.03	99.54
TSC-2A-6	49.17	1.12	5.33	7.71	0.14	13.85	21.37	0.46	0	0.03	99.18
TSC-2A-7	48.69	1.24	5.59	6.35	0.09	14.23	22.09	0.42	0.01	0.04	98.74
TSC-2A-8	49.57	1.18	5.64	6.44	0.1	14.25	22.38	0.32	0	0.03	99.9
TSC-2A-9	49.47	1.14	5.59	6.65	0.1	14.17	22.14	0.42	0	0.01	99.69
TSC-2A-10	48.87	1.19	6.58	7.25	0.09	13.54	22.2	0.48	0.02	0.04	100.26
TSC-2A-11	48.63	1.2	6.49	7.26	0.12	13.75	21.79	0.44	0	0.05	99.71
TSC-2A-12	48.94	1.22	6.33	7.15	0.11	13.77	21.93	0.4	0.01	0.03	99.89
TSC-2A-13	49.2	1.03	5.96	7.03	0.14	13.95	21.88	0.35	0.01	0.07	99.62
TSC-2B-2	49.45	1.28	3.84	8.31	0.19	14.56	20.99	0.54	0	0.05	99.21
TSC-2B-3	48.12	1.51	4.98	7.97	0.14	14.27	20.91	0.55	0.01	0.01	98.47
TSC-2B-4	49.78	0.99	4.17	7.77	0.16	14.93	21.22	0.5	0	0.01	99.53
TSC-2B-5	50.21	0.92	3.64	7.77	0.17	15.17	20.93	0.48	0	0.01	99.31
TSC-2B-6	50.43	0.92	3.78	7.79	0.18	15.24	21.38	0.43	0	0	100.16
TSC-2B-7	50.43	1.13	3.86	7.8	0.17	14.89	21.34	0.37	0	0.01	100
TSC-2B-8	50.83	0.93	3.54	7.93	0.18	14.99	20.85	0.41	0	0.01	99.67
TSC-2B-9	50.96	0.99	3.69	7.94	0.18	14.95	21.13	0.38	0	0	100.21
TSC-2B-10	50.38	0.99	3.76	7.85	0.19	15.22	21.33	0.47	0	0.002	100.18
TSC-2C-1	47.4	2.02	7.67	8.99	0.17	11.96	20.87	0.49	0.01	0.04	99.62
TSC-2C-2	46.54	1.93	7.23	8.73	0.17	12.4	20.59	0.53	0.01	0.06	98.19
TSC-2C-3	46.51	1.96	7.23	8.69	0.15	12.74	20.78	0.48	0	0.04	98.59
TSC-2C-4	46.47	1.94	7.26	9	0.18	13.1	20.74	0.58	0	0.01	99.29
TSC-2C-5	46.71	1.87	7.03	8.84	0.18	12.99	20.79	0.58	0	0.02	99.01
TSC-2C-6	46.93	1.84	7.02	8.76	0.15	13.09	20.81	0.58	0.01	0.02	99.21
TSC-2C-7	47.07	1.83	6.91	8.67	0.17	13.21	20.95	0.53	0	0.03	99.37
TSC-2C-8	46.79	1.87	7.13	8.99	0.17	13.24	20.88	0.52	0	0.01	99.6
TSC-2C-9	46.53	1.89	6.98	8.91	0.17	13.37	21.2	0.56	0	0.02	99.63
TSC-2C-10	49.14	0.88	3.97	7.75	0.17	15.58	21.38	0.58	0.01	0	99.45
TSC-2D-2	48.9	1.42	3.93	7.77	0.16	13.93	21.67	0.35	0	0.04	98.17
TSC-2D-3	49.1	1.4	3.85	7.72	0.14	14.23	21.63	0.41	0.01	0.04	98.53
TSC-2D-4	50.42	1.24	3.51	7.62	0.13	14.55	21.87	0.43	0	0.03	99.79
TSC-2D-5	49.85	1.38	4.01	7.96	0.14	14.33	21.96	0.4	0	0.04	100.06
TSC-2D-6	50.45	1.32	4.01	7.45	0.15	14.28	21.73	0.53	0.01	0.02	99.95
TSC-2D-7	50.01	1.2	3.5	7.9	0.16	14.81	21.75	0.47	0.01	0.01	99.82
TSC-2D-8	49.81	1.42	3.84	7.6	0.17	14.68	22.12	0.45	0	0.02	100.13
TSC-2D-9	49.32	1.58	4.19	8.11	0.16	14.35	21.76	0.4	0	0.03	99.9
TSC-2D-10	46.77	1.55	4.53	8.3	0.17	14.79	21.51	0.52	0	0.01	98.15
TSC-3A-1	49.14	1.61	4.81	7.46	0	13.71	22.47	0.51	0	0	99.72
TSC-3A-2	49.09	1.67	4.73	7.42	0	13.61	22.52	0.46	0	0	99.5
TSC-3A-3	49.01	1.65	4.99	8.19	0	13.31	21.66	0.61	0	0	99.43
TSC-3A-4	48	2.19	5.63	8.61	0	12.67	22.03	0.61	0	0	99.74
TSC-3A-5	48.68	2.02	4.91	8.23	0	12.96	22.16	0.68	0	0	99.64
TSC-3A-6	49.22	2.04	4.13	9.22	0	12.67	22.13	0.66	0.01	0	100.09
TSC-3A-7	47.9	2.31	5.09	8.67	0.02	12.56	22.05	0.63	0	0	99.23
TSC-3A-8	50.42	1.51	2.96	9.24	0.02	12.83	22.01	0.7	0	0	99.69
TSC-3A-9	45.8	2.74	7.3	8.89	0.02	12.1	21.9	0.54	0	0	99.29
TSC-3A-10	49.91	1.39	4.11	7.92	0.01	13.96	21.64	0.57	0	0	99.51
TSC-3A-11	49.49	1.47	4.72	7.33	0.01	13.89	22.09	0.55	0	0	99.55
TSC-3A-12	49.74	1.46	4.61	8.23	0	13.71	21.49	0.57	0	0	99.81
TSC-3B-1	50.23	0.95	4.59	5.24	0	14.97	23.05	0.39	0	0.18	99.6
TSC-3B-2	50.09	0.96	4.77	5.4	0	14.92	22.93	0.43	0	0.17	99.67
TSC-3B-3	49.47	1.14	5.28	5.47	0	14.88	22.82	0.46	0	0.21	99.73
TSC-3B-4	49.35	1.1	5.43	5.64	0	14.62	22.72	0.43	0	0.15	99.44
TSC-3B-5	50.12	0.89	4.79	5.38	0	14.98	22.8	0.4	0	0.19	99.55
TSC-3B-6	49.28	1.14	5.4	5.56	0	14.46	22.84	0.41	0	0.11	99.21
TSC-3B-7	49.33	1.12	5.26	5.4	0.02	14.49	22.85	0.47	0.01	0.24	99.18
TSC-3B-8	49.29	1.01	5.02	5.34	0.02	14.68	22.64	0.5	0	0.22	98.72
TSC-3B-9	49.1	1.56	4.38	7.87	0	13.91	22.15	0.47	0	0	99.45
TSC-3B-10	49.88	1.52	3.86	7.93	0.01	14.08	22.05	0.41	0	0	99.74
TSC-3B-11	49.51	1.17	5.4	5.54	0	14.63	22.98	0.38	0	0.17	99.77
TSC-3B-12	49.41	1.11	5.33	5.48	0	14.49	22.83	0.42	0	0.18	99.26
TSC-3C-1	48.55	2	4.96	8.44	0	13.06	22.2	0.54	0	0.02	99.76
TSC-3C-2	48.06	2.15	5.26	8.53	0	12.91	22.2	0.56	0	0	99.67
TSC-3C-3	48.19	2	4.96	8.52	0	12.97	22.38	0.59	0	0.05	99.66
TSC-3C-4	48	2.12	5.14	8.52	0	12.68	21.96	0.62	0	0	99.04
TSC-3C-5	48.28	2.02	4.93	8.33	0	12.75	22.13	0.64	0	0.02	99.09
TSC-3C-6	47.43	2.46	5.48	8.89	0	12.43	21.93	0.62	0	0	99.24
TSC-3C-7	49.68	1.66	3.69	8.22	0	13.46	21.62	0.61	0	0	98.95
TSC-3C-8	48.78	1.88	4.65	8.46	0	12.98	22.01	0.58	0.01	0.04	99.38
TSC-3C-9	47.95	1.89	5.44	8.35	0	13.23	22.19	0.46	0	0.01	99.52
TSC-3C-10	48.32	2.08	4.94	8.66	0	12.89	21.85	0.64	0	0.02	99.4
TSC-3C-11	47.71	2.36	5.48	8.73	0	12.57	22.07	0.58	0	0	99.5
TSC-3D-1	47.72	2.05	5.72	8.19	0	12.82	22.3	0.56	0	0	99.36
TSC-3D-2	47.94	2.13	5.51	8.46	0	12.97	22.13	0.54	0.01	0	99.69
TSC-3D-3	48.27	1.8	5.25	8.24	0	12.97	22.26	0.58	0.01	0	99.38
TSC-3D-4	48.21	1.99	5.27	7.86	0.03	13.06	22.31	0.52	0	0.01	99.26
TSC-3D-5	47.37	2.27	6.03	8.16	0	12.63	22.38	0.56	0.01	0	99.4
TSC-3D-6	47.61	2.18	5.82	8.37	0	12.55	22.14	0.65	0	0	99.32
TSC-3D-7	48.35	2.16	4.88	8.61	0	12.99	21.72	0.67	0	0	99.38
TSC-3D-8	48.83	1.64	5.04	8.16	0.03	13.2	22.07	0.63	0.01	0	99.61
TSC-3D-9	48.05	1.47	6.25	7.53	0	13.51	22.24	0.51	0	0	99.56
TSC-3D-10	48.65	1.39	5.93	7.52	0	13.72	22.17	0.52	0	0.01	99.92
TSC-7A-1	47.74	1.59	5.46	7.83	0.18	14.04	21.51	0.77	0	0	99.13
TSC-7A-2	48.72	1.4	4.85	7.68	0.18	14.12	21.69	0.64	0	0.02	99.3
TSC-7A-3	48.55	1.48	4.77	7.7	0.17	14.09	21.71	0.47	0	0.04	98.97
TSC-7A-4	49.07	1.4	4.37	7.7	0.16	14.2	21.73	0.56	0.01	0.03	99.23
TSC-7A-5	49.59	1.3	3.93	7.5	0.16	14.26	21.91	0.58	0	0.05	99.28
TSC-7A-6	48.73	1.59	4.54	7.64	0.15	13.73	22.17	0.48	0.02	0.03	99.09
TSC-7A-7	49.01	1.5	4.37	7.73	0.17	13.68	22.06	0.51	0	0.02	99.04
TSC-7A-8	49.31	1.38	4.36	7.52	0.16	13.93	21.93	0.47	0	0.02	99.08
TSC-7A-9	49.92	1.37	4.24	7.5	0.15	13.96	21.86	0.51	0	0.04	99.55
TSC-7A-10	50.13	1.32	4.27	7.46	0.16	13.63	21.72	0.41	0	0.02	99.13
TSC-7B-2	49.94	1.26	3.98	7.38	0.17	14.23	21.94	0.47	0.01	0	99.38
TSC-7B-3	48.58	1.46	4.77	7.28	0.18	13.95	21.97	0.38	0.01	0	98.59
TSC-7B-4	49.14	1.29	4.48	7.49	0.15	14.27	21.66	0.49	0	0.03	98.99
TSC-7B-5	48.32	1.28	4.08	7.23	0.16	14.87	21.8	0.37	0	0.02	98.12
TSC-7B-6	50.09	1.26	3.76	7.52	0.16	14.03	21.56	0.46	0.01	0.01	98.86
TSC-7B-7	49.82	1.22	3.74	7.58	0.19	14.16	21.45	0.47	0	0.02	98.65
TSC-7B-8	46.93	2.04	5.91	7.77	0.14	13.11	21.94	0.46	0	0.05	98.35
TSC-7B-9	47.13	2.09	5.68	8.23	0.15	12.87	21.81	0.49	0	0.01	98.46
TSC-7B-10	47.35	1.87	5.81	7.75	0.15	13.49	21.87	0.6	0.01	0	98.9
TSC-9A-1	47.95	2.58	5.02	9.03	0	12.47	22.06	0.7	0	0.01	99.82
TSC-9A-2	48.04	1.98	5.81	7.42	0	13.23	22.82	0.52	0	0	99.82
TSC-9A-3	48.18	2.22	5.45	8.29	0.05	13.07	22.44	0.72	0	0.03	100.44
TSC-9A-4	47.85	2.09	5.62	7.89	0.03	13.02	22.3	0.58	0	0	99.38
TSC-9A-5	47.06	2.37	6.66	8.02	0.03	12.82	22.89	0.51	0	0	100.37
TSC-9A-6	47.76	2.33	5.93	8.06	0.01	12.82	22.29	0.62	0	0.05	99.86
TSC-9A-7	48.56	1.7	5.27	7.49	0.02	13.54	22.81	0.56	0	0	99.95
TSC-9A-8	49.44	1.68	4.51	7.07	0.01	14.02	22.46	0.48	0	0.01	99.67
TSC-9A-9	49.62	1.67	4.07	7.6	0.02	13.6	21.95	0.68	0	0	99.21
TSC-9A-10	47.12	2.06	6.59	8.45	0	12.7	22.08	0.52	0	0	99.52
TSC-9B-1	47.85	2.13	5.79	7.71	0	13.05	22.35	0.56	0	0.02	99.47
TSC-9B-2	49.76	1.33	4.17	7.54	0.01	14.03	21.87	0.62	0	0.01	99.34
TSC-9B-3	48.41	1.73	5.12	7.63	0.03	13.38	22.2	0.51	0.01	0	99.02
TSC-9B-4	49.42	1.43	4.35	7.07	0.03	14.18	22.46	0.53	0.01	0.01	99.49
TSC-9B-5	49.63	1.51	4.49	7.38	0.02	13.89	21.81	0.62	0.01	0	99.36
TSC-9B-6	50.17	1.42	3.73	7.24	0.02	14.16	22.26	0.5	0	0	99.5
TSC-9B-7	49.73	1.5	4.24	7.51	0.02	13.8	22.1	0.59	0	0	99.48
TSC-9B-8	49.37	1.67	4.44	7.61	0	13.92	22.38	0.62	0	0.04	100.05
TSC-9B-9	49.63	1.46	4.39	7.06	0	14.17	22.66	0.46	0	0	99.83
TSC-9B-10	50.25	1.3	3.71	7.21	0	14.58	22.58	0.44	0	0.01	100.09
TSC-9C-1	46.86	2.55	6.22	8.38	0.02	12.71	22.49	0.59	0	0	99.82
TSC-9C-2	48.48	1.88	5.02	7.65	0.03	13.32	22.52	0.59	0	0	99.49
TSC-9C-3	50.56	1.55	3.26	7.69	0.01	14.3	21.37	0.62	0.01	0	99.37
TSC-9C-4	49.8	1.42	3.97	7.39	0	14.12	21.85	0.49	0.01	0	99.04
TSC-9C-5	49.99	1.41	3.88	7.15	0	14.29	21.91	0.52	0	0	99.15
TSC-9C-6	49.34	1.67	4.39	7.5	0	13.84	21.67	0.58	0.01	0	98.99
TSC-9C-7	49.24	1.63	4.31	7.56	0.01	13.7	21.99	0.53	0	0	98.96
TSC-9C-8	48.81	1.78	5.01	7.59	0	13.48	22.48	0.64	0.01	0	99.8
TSC-9C-9	48.87	1.63	5.16	7.15	0	13.66	22.7	0.53	0.01	0	99.71
TSC-9C-10	46.41	2.54	6.99	8.16	0	12.51	22.64	0.56	0.01	0	99.82

*Operating conditions of the MIT JXA-8200 consisted of a 15 keV accelerating voltage and 10 nA beam current, with all analyses using a focused beam of ~1 μm and 30 s count times. Data were reduced using the CITZAF correction procedure of Armstrong (1995). The few totals lower than 98 wt. % have been omitted.
† All iron reported as FeO

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Neodymium, Hf, and Pb isotopic compositions were measured on the Nu Plasma 500 HR multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) at the Ecole Normale Supérieure de Lyon.

	143Nd/144Nd	εNd †	176Hf/177Hf †	εHf §	206Pb/204Pb §	207Pb/204Pb §	208Pb/204Pb #
TSC-2
WR	0.512952(2)	6.1	0.283035(5)	9.3	20.015	15.668	39.645
cpx	0.512942(3)	5.9	0.283033(4)	9.2	20.014	15.670	39.645
TSC-3
WR	0.512948(3)	6	0.283032(4)	9.2	20.078	15.670	39.666
cpx	0.512937(2)	5.8	0.283047(6)	9.7	20.072	15.668	39.655
TSC-7
WR	0.512929(4)	5.7	0.283012(4)	8.5	19.990	15.676	39.648
cpx	0.512921(2)	5.5	0.283024(6)	8.9	19.946	15.668	39.587
TSC-9
WR	0.512930(3)	5.7	0.283014(4)	8.6	19.987	15.675	39.647
cpx	0.512922(3)	5.5	0.282996(4)	7.9	19.978	15.669	39.620

* WR samples (italicised) are from Bryce et al. (2011) and are reported here for convenience. For the clinopyroxene samples, aliquots of 0.5 to 2 mm clinopyroxene handpicked from the TSC lavas were first leached in hot (~120° C) 6 N HCl to remove any Pb surface contamination following techniques outlined in Blichert-Toft and Albarède (2009). The resulting residues were subsequently digested in a mixture of concentrated HF-HNO₃. Lead was separated prior to Hf and Nd separation using techniques described in Bryce and DePaolo (2004). Total Pb procedural blanks were <40 pg. Hafnium was separated from the Pb column eluent using the three column procedure described for high magnesium samples by Blichert-Toft (2001). Neodymium was from the Pb column eluent, separated from the residue of the first Hf column using a three column procedure starting with a small (0.5 mL) cation exchange resin (AG50x8) to strip off Fe and other major ions. The REE-rich elutions were subsequently passed through a 0.5 mL column filled with TRU-Spec resin to concentrate further the REEs, where the 2 M HNO₃ was used to elute other ions and the REEs were collected with water. Nd was finally separated from Sm using a 1.6 mL LN-Spec column and a 0.25 M HCl elution. Total Nd procedural blanks were <30 pg and total Hf procedural blanks were <20 pg.

† For the Nd isotopic measurements, instrument performance was monitored with a laboratory solution, and accuracy was assessed through repeated (n = 9) analyses of BCR-1 which yielded 0.512638 (with external 2σ = 0.000020). ε_Nd was calculated using a CHUR value of ¹⁴³Nd/¹⁴⁴Nd = 0.512638.

§ Hf isotopic analyses were obtained following the techniques described in Blichert-Toft et al. (1997). The 100 ppb JMC 475 Hf standard, run throughout the analytical session (n = 21) to monitor instrument performance, yielded ¹⁷⁶Hf/¹⁷⁷Hf = 0.282160 (with external 2σ = 0.000015). ε_Hf was calculated using a CHUR value of ¹⁷⁶Hf/¹⁷⁷Hf = 0.282772 (Blichert-Toft and Albarède, 1997).

# Mass fractionation in Pb isotope analyses was corrected via Tl normalisation as described in White et al. (2000), and ratios were additionally adjusted for drift using the standard bracketing technique outlined in Albarède et al. (2004) using the NIST SRM values reported in Eisele et al. (2003). Four NIST SRM 981 samples, run as “blind” amongst the 17 bracketing standards analysed, yielded averages (with 2σ external precision) of ²⁰⁸Pb/²⁰⁴Pb = 36.7271 (0.0019), ²⁰⁷Pb/²⁰⁴Pb = 15.4978 (0.0009) and ²⁰⁶Pb/²⁰⁴Pb = 16.9408 (0.0012).

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Clinopyroxene Thermobarometry Model Evaluation

Experimental dataset
Although cpx-liquid thermobarometry (Putirka et al., 2003) has been used successfully with recent Etna lavas (e.g., Armienti et al., 2007), single-cpx models avoid the additional uncertainty inherent in back-calculating plausible equilibrium liquids. Crystallisation temperatures and pressures were solved iteratively using a single-clinopyroxene thermometer, Eq. 32d in Putirka (2008) but referred to here as Eq. S-2, and single-clinopyroxene barometer for hydrous systems (Eq. 32b of that work, here as Eq. S-3).

This section details the selection criteria for the experimental clinopyroxene-liquid pairs bracketing the Timpe Santa Caterina whole rock (Bryce, 1998) and clinopyroxene compositions (Table S-4) in order to evaluate the accuracy of published clinopyroxene thermobarometric models for alkaline magmas. Experiments containing coexisting clinopyroxene and liquid phases at 0-1.0 GPa were culled from the Library of Experimental Phase Relations (LEPR) database (Hirschmann et al., 2008). Liquid composition constraints consisted of SiO₂ = 45–52 wt. %, Al₂O₃ = 15–20 wt. %, and MgO < 8.1 wt.%, ranges designed to span the potential TSC liquid compositions coexisting with clinopyroxene. Experiments were further culled by limiting clinopyroxene Al₂O₃ content to <9 wt. % and CaO wt. % to within 2 wt. % of the upper and lower concentrations observed in TSC clinopyroxene (range 18–25 wt. %). This produced a clinopyroxene-liquid dataset of >100 pairs from experimental studies (Hess et al., 1978; Mahood and Baker, 1986; Baker et al., 1987; Sack et al., 1987; Tormey et al., 1987; Gee and Sack, 1988; Kelemen et al., 1990; Kennedy et al., 1990; Sisson and Grove, 1993; Kawamoto, 1996; Métrich and Rutherford, 1998; Wood and Trigila, 2001; Pichavant et al., 2002; Grove et al., 2003; Barclay and Carmichael, 2004; Nekvasil et al., 2004; Di Carlo et al., 2006; Feig et al., 2006; Scoates et al., 2006; Almeev et al., 2007; Villiger et al., 2007; Mercer and Johnston, 2008; Conte et al., 2009).

	Lava		Clinopyroxene
	Low	High	Low	High
SiO2	46.6	50.7	45.8	51
TiO2	1.6	2.1	0.9	2.7
Al2O3	16.8	19.8	3	7.7
FeO*	8.2	10.9	5.2	9.2
MnO	0.15	0.19	0	0.19
MgO	3.4	6.3	12	15.6
CaO	8.7	10.9	20.3	23.1
Na2O	3.7	5.5	0.3	0.8
K2O	1	2.1	0	0.02
P2O5	0.5	1.4	0	0.24

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P-T estimates for TSC clinopyroxene crystallisation based on these models indicate they record a wide range of crustal pressures, from just above the current Moho to the near-surface, with a corresponding temperature range of 1175–1060 °C. Because the barometer requires temperature as an input, sensitivity to temperature was evaluated. Varying barometer input temperatures (obtained from single-cpx thermometer Eq. 32d of Putirka, 2008) by ±50 ºC yields calculated pressures on average 0.12 GPa lower and 0.18 GPa higher, respectively, for these compositions. Undegassed melt H₂O content was assumed to be 3 wt. %, after Métrich et al. (2004). However, adopting a H₂O input of 2 wt. % generates pressure estimates averaging ~0.05 GPa lower and temperatures ~5 ºC lower than for 3 wt. % H₂O.

Figure 1b shows proportions of calculated pressures (n = 287) from single-clinopyroxene thermobarometry of ancient (>80 ka) Etna clinopyroxene compositions of those reported here and previous workers (Tanguy, 1978; Nazzareni et al., 2003; Lopez et al., 2006; Ferlito et al., 2010; Giacomoni et al., 2016).

alphaMELTS v. 1.4 modelling of clinopyroxene trace element content (Fig. S-3)
TSC clinopyroxene trace elements are compared with the evolution of clinopyroxene compositions during cooling of magmas at 1.0, 0.6, and 0.2 GPa. Clinopyroxene fractionating from two mantle melts are shown in Figure S-2: a dry pyroxenite/hydrated (3 wt. % H₂O) peridotite melt mixture (solid lines) and a less hydrated (1 wt. % H₂O) peridotite melt (dashed lines).

Pyroxenite/peridotite mix composition. A hypothetical melt composition, ‘10pyrper03’, containing 10:90 pyroxenite/peridotite melt was calculated from liquids generated using the alphaMELTS software interface to access the (pH)MELTS family of modelling algorithms. The pyroxenite component was obtained from batch decompression melting of a dry pyroxenite with an average composition from Hyblean pyroxenite xenoliths XIP-4 and XIP-14 reported in Correale et al. (2012). The same melting conditions were applied to a Hyblean peridotite composition (average of xenoliths XIH-1 and XIH-2, Correale et al., 2012) hydrated with 3 wt. % H₂O. The pyroxenite and hydrated peridotite both generated 10 % melting at ~1.5 GPa at a pHMELTS input temperature in the 1350–1360 °C range and initial f_O2 of NNO+1. The 10:90 ratio was chosen because calculated Y/La concentrations of clinopyroxene coexisting with this melt approximately match the most primitive clinopyroxene in the TSC suite.

Peridotite composition. The hypothetical peridotite melt ‘perid01_20kb’ is the liquid phase produced by 5 % batch decompression melting at 2.0 GPa and 1435 °C using pHMELTS, which is calibrated for pressures between 4 and 1 GPa. It was also chosen for its ability to fractionate clinopyroxene with calculated Y/La similar to TSC clinopyroxene.

To better approximate the likely complex transport, magma replenishment, and crystallisation processes beneath ancient Etna, clinopyroxene compositional evolution in Y/La space was calculated separately as what would fractionate from batch liquids at every decreasing 20 °C temperature step in MELTS. MELTS has been calibrated for pressures at or less than 1.0 GPa and all modelled clinopyroxene compositional paths shown are based on MELTS simulations of magma differentiation (Ghiorso et al., 1995). The alphaMELTS (Smith and Asimow, 2005) default partition coefficients (Kd) of McKenzie and O’Nions (1991) were used for all trace elements in both generating the initial melts and for the isobaric fractionation runs.

Open system behaviour was approximated via a two-step process. First, MELTS batch liquids were generated using the McKenzie and O’Nions Kd values likely relevant to mantle and lower crustal conditions. Second, at each temperature step a hypothetical trace element composition of clinopyroxene instantaneously crystallising from the liquid was calculated using Kds more representative of low pressure partitioning behaviour. Models reported here use the Kds of Hauri et al. (1994) for La and Ce (0.0515 and 0.108 respectively) and Dorais and Tubrett (2008) for Y (0.575), which was calculated for use with the Hauri et al. (1994) Kd values from the partitioning model for clinopyroxene Kds of Wood and Blundy (1997). These are similar to other low pressure Kd datasets reported in Hill et al. (2000) and Laubier et al. (2014), though the choice of a somewhat low value for La is needed to reproduce the highest Y/La of more primitive TSC clinopyroxenes. Generally, the primary difference in the Kd datasets used in these models is the Y partitioning behaviour between clinopyroxene and melt, which is taken to be 0.20 at high pressure and 0.575 at low pressure. Attempts to use the hydrous system model for clinopyroxene Kd values of Sun and Liang (2012), which calculates comparatively low Kd values relative to previously mentioned models and datasets, produced poor fits to TSC clinopyroxene compositions.

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The effects of apatite saturation are considered, as whole rock CIPW norm abundances of apatite range from ~1 to 3 % in TSC lavas. Middle rare earth elements (MREE) partition more strongly into apatite than light (L-) and heavy (H-) REE, with Y behaviour being similar to that of HREE. The dominant influence of apatite would be to shift modelled clinopyroxene trace element evolution paths toward lower Ce values. Simple fractional crystallisation modelling of apatite fractionation using the apatite/liquid Kds of Prowatke and Klemme (2006) early from hypothetical hydrated peridotite and mixed component source melts would extend possible compositions directly away from the observed TSC clinopyroxene trends in Y/La vs. Ce space. However, the effects of apatite fractionation on liquids in equilibrium with the most evolved TSC-2 and TSC-7 clinopyroxenes could significantly drive liquids towards lower Ce that could reproduce the TSC-3, TSC-9, and modern Etna clinopyroxene trend. In that scenario, a hydrated peridotite source is not needed and TSC and modern Etna clinopyroxene can be successfully modelled as the products of a mixed hydrated peridotite/10 % pyroxenite source with varying degrees of apatite fractionation during storage and ascent prior to eruption.

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