Tracking Volatile Behaviour in Sub-volcanic Plumbing Systems Using Apatite and Glass: Insights into Pre-eruptive Processes at Campi Flegrei, Italy

Tracking Volatile Behaviour in Sub-volcanic Plumbing Systems Using Apatite and Glass: Insights... Abstract Volatile elements play an important role in many aspects of the physicochemical architecture of sub-volcanic plumbing systems, from the liquid line of descent to the dynamics of magma storage and eruption. However, it remains difficult to constrain the behaviour of magmatic volatiles on short timescales before eruption using established petrological techniques (e.g. melt inclusions); specifically, in the final days to months of magma storage. This study presents a detailed model of pre-eruptive volatile behaviour in the Campi Flegrei system (Italy), through combined analyses of apatite crystals and glass. The deposits of eight eruptions were examined, covering the full spectrum of melt compositions, eruptive styles and periods of activity at Campi Flegrei in the past 15 kyr. Measured apatite compositions are compared with thermodynamic models that predict the evolution of the crystal compositions during different fractional crystallization scenarios, including (1) volatile-undersaturated conditions, (2) H2O-saturated conditions and (3) varying P–T conditions. The compositions of clinopyroxene-hosted and biotite-hosted apatite inclusions are consistent with crystallization under volatile-undersaturated conditions that persisted until late in magmatic evolution. Apatite microphenocrysts show significantly more compositional diversity, interpreted to reflect a mixed cargo of crystals derived from volatile-undersaturated melts at depth and melts that have undergone cooling and degassing in discrete shallow-crustal magma bodies. Apatite microphenocrysts from lavas show some re-equilibration during cooling at the surface. Clinopyroxene-hosted melt inclusions within the samples typically contain 2–4 wt % H2O, indicating that they have been reset during temporary magma storage at 1–3 km depth, similar to the depth of sill emplacement during recent seismic crises at Campi Flegrei. Comparable apatite compositional trends are identified in each explosive eruption analysed, regardless of volume, composition or eruption timing. However, apatites from the different epochs of activity appear to indicate subtle changes in the H2O content of the parental melt feeding the Campi Flegrei system over time. This study demonstrates the potential utility of integrated apatite and glass analysis for investigating pre-eruptive volatile behaviour in apatite-bearing magmas. INTRODUCTION Magmatic volatiles (H2O, CO2, halogens and SO2) are minor but important constituents of most silicate melts, and affect almost every aspect of magmatic evolution and eruption. Volatiles influence mineral phase stability and the liquid line of descent (Grove et al., 2003; Zimmer et al., 2010), as well as melt density (Lange & Carmichael, 1990) and viscosity (Giordano et al., 2008), thus exerting a major control on the depths of magma storage and the crustal-scale structure of sub-volcanic systems (Annen et al., 2006). Volatile exsolution and expansion drives volcanic eruptions, and the pre-eruptive behaviour of volatiles plays an important role in controlling the style and tempo of volcanism at the Earth’s surface (Roggensack et al., 1997; Huppert & Woods, 2002; Cashman, 2004; Edmonds, 2008). Table 1: Summary of eruption deposits analysed, including age estimate, deposit characteristics (i.e. eruption style), erupted volume (i.e. magnitude estimate), average matrix glass composition, vent location and sampling location Epoch Eruption Sample number Age (cal. years BP) Deposit type Erupted volume (km3) Average matrix glass composition Vent location* Sampling location UTM X UTM Y UTM X UTM Y Monte Nuovo CF195 1538 CE* Pyroclastic density current deposit ∼0·03* Phonolite 423095 4520870 423277 4520614 Epoch 3 Astroni 1 CF69 4155–4357* Ash fall with some lapilli layers ∼0·06* Phonolite 427999 4522122 428859* 4523584* Accademia CF163 4205–4507*1 Lava dome <0·01* Trachyte§ 427551 4519282 427597 4519562 Santa Maria delle Grazie CF200 4383–4507* Shallow feeder dyke <0·01* Latite‖ 427625 4519806 427421 4518909 Epoch 2 Baia–Fondi di Baia CF88 9525–9705* Pumice fall 0·02–0·04† Trachyte 421855 4517930 421844* 4518253* Epoch 1 Pisani 1 CF25 10516–12107*2 Scoria fall 0·1–0·3* Tephri-phonolite‒trachy-andesite 428260 4523970 430237* 4525994* Pomici Principali CF6 11907–12107* Plinian fall (B3 unit) 0·43–1·28‡ Tephri-phonolite‒phonolite 428698 4522284 433890* 4522346* Minopoli 1 CF13 11907–12725*3 Scoria fall <0·1* Phono-tephrite‒tephri-phonolite 432400 4522670 432805* 4522632* Epoch Eruption Sample number Age (cal. years BP) Deposit type Erupted volume (km3) Average matrix glass composition Vent location* Sampling location UTM X UTM Y UTM X UTM Y Monte Nuovo CF195 1538 CE* Pyroclastic density current deposit ∼0·03* Phonolite 423095 4520870 423277 4520614 Epoch 3 Astroni 1 CF69 4155–4357* Ash fall with some lapilli layers ∼0·06* Phonolite 427999 4522122 428859* 4523584* Accademia CF163 4205–4507*1 Lava dome <0·01* Trachyte§ 427551 4519282 427597 4519562 Santa Maria delle Grazie CF200 4383–4507* Shallow feeder dyke <0·01* Latite‖ 427625 4519806 427421 4518909 Epoch 2 Baia–Fondi di Baia CF88 9525–9705* Pumice fall 0·02–0·04† Trachyte 421855 4517930 421844* 4518253* Epoch 1 Pisani 1 CF25 10516–12107*2 Scoria fall 0·1–0·3* Tephri-phonolite‒trachy-andesite 428260 4523970 430237* 4525994* Pomici Principali CF6 11907–12107* Plinian fall (B3 unit) 0·43–1·28‡ Tephri-phonolite‒phonolite 428698 4522284 433890* 4522346* Minopoli 1 CF13 11907–12725*3 Scoria fall <0·1* Phono-tephrite‒tephri-phonolite 432400 4522670 432805* 4522632* Erupted volumes are given as dense rock equivalent. Where exposure permitted, samples were collected vertically through volcaniclastic units and included both lapilli- and ash-sized material. The Pomici Principali sample represents only the B3 Plinian phase of the eruption and the Baia–Fondi di Baia sample comprises only the basal Baia fallout units. Samples from the deposits of these eruptions show only limited diversity in glass compositions (Smith et al., 2011) and the analysed samples are therefore assumed representative of the bulk erupted material. * Data from Smith et al. (2011). All ages of Smith et al. (2011) have been recalibrated using IntCal13 (Reimer et al., 2013). † Data from Pistolesi et al. (2017). ‡ Data from Bevilacqua et al. (2016). §Whole-rock composition from Melluso et al. (2012). ‖Whole-rock composition from Isaia et al. (2009). 1Eruption not directly dated but stratigraphically older than the Solfatara eruption (4205–4427 years BP) and younger than Santa Maria delle Grazie. 2Eruption not directly dated but stratigraphically older than Pisani 3 (10 517–10 760 years BP) and younger than Pomici Principali. 3Eruption not directly dated but stratigraphically older than Pomici Principali and younger than Archiaverno (12 579–12 725 years BP). Table 1: Summary of eruption deposits analysed, including age estimate, deposit characteristics (i.e. eruption style), erupted volume (i.e. magnitude estimate), average matrix glass composition, vent location and sampling location Epoch Eruption Sample number Age (cal. years BP) Deposit type Erupted volume (km3) Average matrix glass composition Vent location* Sampling location UTM X UTM Y UTM X UTM Y Monte Nuovo CF195 1538 CE* Pyroclastic density current deposit ∼0·03* Phonolite 423095 4520870 423277 4520614 Epoch 3 Astroni 1 CF69 4155–4357* Ash fall with some lapilli layers ∼0·06* Phonolite 427999 4522122 428859* 4523584* Accademia CF163 4205–4507*1 Lava dome <0·01* Trachyte§ 427551 4519282 427597 4519562 Santa Maria delle Grazie CF200 4383–4507* Shallow feeder dyke <0·01* Latite‖ 427625 4519806 427421 4518909 Epoch 2 Baia–Fondi di Baia CF88 9525–9705* Pumice fall 0·02–0·04† Trachyte 421855 4517930 421844* 4518253* Epoch 1 Pisani 1 CF25 10516–12107*2 Scoria fall 0·1–0·3* Tephri-phonolite‒trachy-andesite 428260 4523970 430237* 4525994* Pomici Principali CF6 11907–12107* Plinian fall (B3 unit) 0·43–1·28‡ Tephri-phonolite‒phonolite 428698 4522284 433890* 4522346* Minopoli 1 CF13 11907–12725*3 Scoria fall <0·1* Phono-tephrite‒tephri-phonolite 432400 4522670 432805* 4522632* Epoch Eruption Sample number Age (cal. years BP) Deposit type Erupted volume (km3) Average matrix glass composition Vent location* Sampling location UTM X UTM Y UTM X UTM Y Monte Nuovo CF195 1538 CE* Pyroclastic density current deposit ∼0·03* Phonolite 423095 4520870 423277 4520614 Epoch 3 Astroni 1 CF69 4155–4357* Ash fall with some lapilli layers ∼0·06* Phonolite 427999 4522122 428859* 4523584* Accademia CF163 4205–4507*1 Lava dome <0·01* Trachyte§ 427551 4519282 427597 4519562 Santa Maria delle Grazie CF200 4383–4507* Shallow feeder dyke <0·01* Latite‖ 427625 4519806 427421 4518909 Epoch 2 Baia–Fondi di Baia CF88 9525–9705* Pumice fall 0·02–0·04† Trachyte 421855 4517930 421844* 4518253* Epoch 1 Pisani 1 CF25 10516–12107*2 Scoria fall 0·1–0·3* Tephri-phonolite‒trachy-andesite 428260 4523970 430237* 4525994* Pomici Principali CF6 11907–12107* Plinian fall (B3 unit) 0·43–1·28‡ Tephri-phonolite‒phonolite 428698 4522284 433890* 4522346* Minopoli 1 CF13 11907–12725*3 Scoria fall <0·1* Phono-tephrite‒tephri-phonolite 432400 4522670 432805* 4522632* Erupted volumes are given as dense rock equivalent. Where exposure permitted, samples were collected vertically through volcaniclastic units and included both lapilli- and ash-sized material. The Pomici Principali sample represents only the B3 Plinian phase of the eruption and the Baia–Fondi di Baia sample comprises only the basal Baia fallout units. Samples from the deposits of these eruptions show only limited diversity in glass compositions (Smith et al., 2011) and the analysed samples are therefore assumed representative of the bulk erupted material. * Data from Smith et al. (2011). All ages of Smith et al. (2011) have been recalibrated using IntCal13 (Reimer et al., 2013). † Data from Pistolesi et al. (2017). ‡ Data from Bevilacqua et al. (2016). §Whole-rock composition from Melluso et al. (2012). ‖Whole-rock composition from Isaia et al. (2009). 1Eruption not directly dated but stratigraphically older than the Solfatara eruption (4205–4427 years BP) and younger than Santa Maria delle Grazie. 2Eruption not directly dated but stratigraphically older than Pisani 3 (10 517–10 760 years BP) and younger than Pomici Principali. 3Eruption not directly dated but stratigraphically older than Pomici Principali and younger than Archiaverno (12 579–12 725 years BP). Table 2: Major and volatile element analyses of representative Campi Flegrei glasses Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Analysis #: CF195_cp x113_m6 CF195_cp x64_m1 CF195_cp x86_m2 CF195_cp x86_m3 CF195_cp x110_m1 CF195_cp x113_m7 CF195_cp x122_m1 CF195_cp x122_m2 CF195_cp x123_m3 CF195_cp x137_m5 Type: mi mi mi mi mi mi mi mi mi mi SiO2 58·77 57·35 57·81 56·19 58·05 57·63 58·35 58·26 59·68 58·71 Na2O 4·45 4·04 4·11 3·94 5·04 4·65 4·20 4·08 5·03 4·42 MgO 0·55 0·77 0·75 0·74 0·76 0·59 0·87 0·81 0·51 0·70 Al2O3 18·17 17·70 18·27 17·26 16·54 18·02 18·03 18·12 16·97 17·71 K2O 8·40 8·57 8·49 7·89 6·86 8·37 8·48 8·94 7·43 8·42 CaO 2·22 2·59 2·55 2·48 2·72 2·26 2·81 2·83 2·33 2·24 TiO2 0·43 0·48 0·48 0·42 0·55 0·46 0·50 0·44 0·53 0·49 MnO 0·09 0·09 0·11 0·15 0·19 0·08 0·10 0·12 0·12 0·11 FeOt 3·31 3·82 3·46 3·39 3·96 3·38 3·83 3·66 3·85 3·37 P2O5 0·08 0·15 0·13 0·14 0·08 0·12 0·13 0·13 0·10 0·11 Cl 0·95 0·66 0·73 0·64 0·85 0·84 0·67 0·66 0·94 0·77 F 0·25 0·22 0·23 0·22 0·22 0·28 0·25 0·22 0·23 0·28 H2O 2·82 3·48 2·84 5·56 3·47 2·45 2·44 1·04 2·28 2·54 Total 100·47 99·93 99·96 99·01 99·29 99·12 100·67 99·31 100·01 99·87 Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Astroni 1 Astroni 1 Astroni 1 Analysis #: CF195_cp x159_m4 CF195_cp x188_m1 VF55_cf19 5_1_1 VF55_cf19 5_2_1 VF55_cf19 5_3_1 VF55_cf19 5_4_1 VF55_cf19 5_4_2 CF69_cp x22_m1 CF69_cp x23_m2 CF69_cp x55_m1 Type: mi mi mg mg mg mg mg mi mi mi SiO2 57·83 58·59 56·50 57·19 58·62 57·66 57·48 57·70 59·17 56·74 Na2O 4·85 4·77 6·88 7·88 7·56 7·69 7·29 4·39 4·25 4·26 MgO 0·66 0·68 0·21 0·25 0·28 0·17 0·18 0·65 0·42 0·54 Al2O3 17·10 17·52 18·28 18·79 19·04 18·69 18·87 17·90 17·84 18·07 K2O 7·18 8·25 6·88 7·23 7·25 7·20 7·30 8·08 8·36 8·89 CaO 2·59 2·52 1·81 1·51 1·66 1·69 1·75 2·47 2·19 2·17 TiO2 0·50 0·47 0·49 0·50 0·39 0·45 0·43 0·45 0·49 0·41 MnO 0·20 0·13 0·24 0·37 0·20 0·20 0·28 0·10 0·19 0·04 FeOt 3·91 3·38 3·08 3·30 2·74 2·89 3·19 3·36 3·65 3·15 P2O5 0·15 0·11 0·01 0·00 0·00 0·05 0·07 0·12 0·10 0·08 Cl 0·89 0·78 0·90 0·97 0·97 1·05 1·17 0·96 1·00 0·87 F 0·24 0·32 1·21 0·65 0·73 0·82 0·68 0·28 0·28 0·26 H2O 3·71 2·38 0·88 0·76 0·97 1·06 1·08 2·37 2·22 2·12 Total 99·80 99·88 97·36 99·41 100·41 99·60 99·77 98·82 100·15 97·60 Eruption: Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Analysis #: CF69_cpx 55_m2 CF69_cpx 66_m1 CF69_cpx 66_m3 CF69_cpx 82_m1 CF69_cpx 91_m1 CF69_cpx 92_m1 CF69_cpx 97_m3 CF69_cpx 113_m1 CF69_cpx 116_m1 CF69_cpx 127_m1 Type: mi mi mi mi mi mi mi mi mi mi SiO2 56·99 54·97 56·56 56·78 58·21 57·38 57·73 56·74 56·44 56·55 Na2O 4·52 4·15 4·02 4·20 4·60 4·35 4·46 4·76 3·65 4·22 MgO 0·53 0·61 0·72 0·50 0·51 0·76 0·54 0·55 0·78 0·58 Al2O3 17·82 17·60 18·24 17·90 17·67 18·60 17·91 17·51 18·40 17·65 K2O 8·50 8·55 8·83 8·35 8·37 8·44 8·27 8·57 8·84 8·28 CaO 2·15 2·43 2·62 2·07 2·03 2·47 2·34 2·17 2·37 2·34 TiO2 0·44 0·47 0·47 0·45 0·48 0·41 0·45 0·45 0·51 0·45 MnO 0·13 0·09 0·12 0·19 0·20 0·11 0·12 0·15 0·02 0·10 FeOt 3·37 3·76 4·20 3·40 3·40 2·85 3·38 3·19 3·27 3·84 P2O5 0·10 0·14 0·13 0·13 0·08 0·17 0·08 0·08 0·15 0·15 Cl 0·93 0·75 0·69 0·91 1·03 0·84 0·90 0·93 0·73 0·82 F 0·25 0·21 0·23 0·28 0·31 0·30 0·25 0·25 0·22 0·20 H2O 2·56 2·21 2·58 2·29 2·27 2·21 2·00 2·62 2·33 2·51 Total 98·28 95·94 99·41 97·46 99·16 98·90 98·43 97·97 97·71 97·70 Eruption: Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Analysis #: CF69_cpx 127_m3 CF69_cpx 130_m1 CF69_cpx 138_m2 CF69_cpx 156_m2 CF69_cpx 182_m1 CF69_cpx 182_m2 VF55_cf69 _2_1 VF55_cf69 _3_1 VF55_cf69 _5_1 VF55_cf69 _6_1 Type: mi mi mi mi mi mi mg mg mg mg SiO2 57·17 56·80 55·39 58·52 55·35 55·59 59·14 57·69 59·43 58·83 Na2O 4·07 4·51 4·62 4·56 3·76 3·87 3·90 4·38 4·67 4·50 MgO 0·54 0·55 0·42 0·45 0·71 0·77 0·54 0·50 0·49 0·58 Al2O3 17·63 17·67 17·09 17·12 17·52 17·53 18·37 17·85 18·09 18·11 K2O 8·36 8·37 8·48 8·03 8·53 8·48 8·61 8·47 8·44 8·56 CaO 2·31 2·30 2·01 2·23 2·64 2·70 2·29 2·28 2·45 2·36 TiO2 0·49 0·51 0·40 0·48 0·48 0·50 0·48 0·42 0·46 0·37 MnO 0·14 0·11 0·13 0·16 0·12 0·17 0·16 0·17 0·16 0·07 FeOt 3·60 3·40 3·34 3·53 3·90 3·39 3·27 3·31 3·42 3·41 P2O5 0·16 0·10 0·06 0·09 0·20 0·12 0·04 0·09 0·09 0·05 Cl 0·88 0·93 0·97 0·91 0·74 0·73 0·91 0·91 0·94 0·92 F 0·20 0·28 0·27 0·26 0·19 0·21 0·25 0·26 0·22 0·25 H2O 2·57 2·43 2·69 2·30 2·39 2·51 0·71 0·67 0·20 1·26 Total 98·12 97·95 95·85 98·63 96·52 96·58 98·67 96·99 99·06 99·27 Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Analysis #: CF195_cp x113_m6 CF195_cp x64_m1 CF195_cp x86_m2 CF195_cp x86_m3 CF195_cp x110_m1 CF195_cp x113_m7 CF195_cp x122_m1 CF195_cp x122_m2 CF195_cp x123_m3 CF195_cp x137_m5 Type: mi mi mi mi mi mi mi mi mi mi SiO2 58·77 57·35 57·81 56·19 58·05 57·63 58·35 58·26 59·68 58·71 Na2O 4·45 4·04 4·11 3·94 5·04 4·65 4·20 4·08 5·03 4·42 MgO 0·55 0·77 0·75 0·74 0·76 0·59 0·87 0·81 0·51 0·70 Al2O3 18·17 17·70 18·27 17·26 16·54 18·02 18·03 18·12 16·97 17·71 K2O 8·40 8·57 8·49 7·89 6·86 8·37 8·48 8·94 7·43 8·42 CaO 2·22 2·59 2·55 2·48 2·72 2·26 2·81 2·83 2·33 2·24 TiO2 0·43 0·48 0·48 0·42 0·55 0·46 0·50 0·44 0·53 0·49 MnO 0·09 0·09 0·11 0·15 0·19 0·08 0·10 0·12 0·12 0·11 FeOt 3·31 3·82 3·46 3·39 3·96 3·38 3·83 3·66 3·85 3·37 P2O5 0·08 0·15 0·13 0·14 0·08 0·12 0·13 0·13 0·10 0·11 Cl 0·95 0·66 0·73 0·64 0·85 0·84 0·67 0·66 0·94 0·77 F 0·25 0·22 0·23 0·22 0·22 0·28 0·25 0·22 0·23 0·28 H2O 2·82 3·48 2·84 5·56 3·47 2·45 2·44 1·04 2·28 2·54 Total 100·47 99·93 99·96 99·01 99·29 99·12 100·67 99·31 100·01 99·87 Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Astroni 1 Astroni 1 Astroni 1 Analysis #: CF195_cp x159_m4 CF195_cp x188_m1 VF55_cf19 5_1_1 VF55_cf19 5_2_1 VF55_cf19 5_3_1 VF55_cf19 5_4_1 VF55_cf19 5_4_2 CF69_cp x22_m1 CF69_cp x23_m2 CF69_cp x55_m1 Type: mi mi mg mg mg mg mg mi mi mi SiO2 57·83 58·59 56·50 57·19 58·62 57·66 57·48 57·70 59·17 56·74 Na2O 4·85 4·77 6·88 7·88 7·56 7·69 7·29 4·39 4·25 4·26 MgO 0·66 0·68 0·21 0·25 0·28 0·17 0·18 0·65 0·42 0·54 Al2O3 17·10 17·52 18·28 18·79 19·04 18·69 18·87 17·90 17·84 18·07 K2O 7·18 8·25 6·88 7·23 7·25 7·20 7·30 8·08 8·36 8·89 CaO 2·59 2·52 1·81 1·51 1·66 1·69 1·75 2·47 2·19 2·17 TiO2 0·50 0·47 0·49 0·50 0·39 0·45 0·43 0·45 0·49 0·41 MnO 0·20 0·13 0·24 0·37 0·20 0·20 0·28 0·10 0·19 0·04 FeOt 3·91 3·38 3·08 3·30 2·74 2·89 3·19 3·36 3·65 3·15 P2O5 0·15 0·11 0·01 0·00 0·00 0·05 0·07 0·12 0·10 0·08 Cl 0·89 0·78 0·90 0·97 0·97 1·05 1·17 0·96 1·00 0·87 F 0·24 0·32 1·21 0·65 0·73 0·82 0·68 0·28 0·28 0·26 H2O 3·71 2·38 0·88 0·76 0·97 1·06 1·08 2·37 2·22 2·12 Total 99·80 99·88 97·36 99·41 100·41 99·60 99·77 98·82 100·15 97·60 Eruption: Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Analysis #: CF69_cpx 55_m2 CF69_cpx 66_m1 CF69_cpx 66_m3 CF69_cpx 82_m1 CF69_cpx 91_m1 CF69_cpx 92_m1 CF69_cpx 97_m3 CF69_cpx 113_m1 CF69_cpx 116_m1 CF69_cpx 127_m1 Type: mi mi mi mi mi mi mi mi mi mi SiO2 56·99 54·97 56·56 56·78 58·21 57·38 57·73 56·74 56·44 56·55 Na2O 4·52 4·15 4·02 4·20 4·60 4·35 4·46 4·76 3·65 4·22 MgO 0·53 0·61 0·72 0·50 0·51 0·76 0·54 0·55 0·78 0·58 Al2O3 17·82 17·60 18·24 17·90 17·67 18·60 17·91 17·51 18·40 17·65 K2O 8·50 8·55 8·83 8·35 8·37 8·44 8·27 8·57 8·84 8·28 CaO 2·15 2·43 2·62 2·07 2·03 2·47 2·34 2·17 2·37 2·34 TiO2 0·44 0·47 0·47 0·45 0·48 0·41 0·45 0·45 0·51 0·45 MnO 0·13 0·09 0·12 0·19 0·20 0·11 0·12 0·15 0·02 0·10 FeOt 3·37 3·76 4·20 3·40 3·40 2·85 3·38 3·19 3·27 3·84 P2O5 0·10 0·14 0·13 0·13 0·08 0·17 0·08 0·08 0·15 0·15 Cl 0·93 0·75 0·69 0·91 1·03 0·84 0·90 0·93 0·73 0·82 F 0·25 0·21 0·23 0·28 0·31 0·30 0·25 0·25 0·22 0·20 H2O 2·56 2·21 2·58 2·29 2·27 2·21 2·00 2·62 2·33 2·51 Total 98·28 95·94 99·41 97·46 99·16 98·90 98·43 97·97 97·71 97·70 Eruption: Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Analysis #: CF69_cpx 127_m3 CF69_cpx 130_m1 CF69_cpx 138_m2 CF69_cpx 156_m2 CF69_cpx 182_m1 CF69_cpx 182_m2 VF55_cf69 _2_1 VF55_cf69 _3_1 VF55_cf69 _5_1 VF55_cf69 _6_1 Type: mi mi mi mi mi mi mg mg mg mg SiO2 57·17 56·80 55·39 58·52 55·35 55·59 59·14 57·69 59·43 58·83 Na2O 4·07 4·51 4·62 4·56 3·76 3·87 3·90 4·38 4·67 4·50 MgO 0·54 0·55 0·42 0·45 0·71 0·77 0·54 0·50 0·49 0·58 Al2O3 17·63 17·67 17·09 17·12 17·52 17·53 18·37 17·85 18·09 18·11 K2O 8·36 8·37 8·48 8·03 8·53 8·48 8·61 8·47 8·44 8·56 CaO 2·31 2·30 2·01 2·23 2·64 2·70 2·29 2·28 2·45 2·36 TiO2 0·49 0·51 0·40 0·48 0·48 0·50 0·48 0·42 0·46 0·37 MnO 0·14 0·11 0·13 0·16 0·12 0·17 0·16 0·17 0·16 0·07 FeOt 3·60 3·40 3·34 3·53 3·90 3·39 3·27 3·31 3·42 3·41 P2O5 0·16 0·10 0·06 0·09 0·20 0·12 0·04 0·09 0·09 0·05 Cl 0·88 0·93 0·97 0·91 0·74 0·73 0·91 0·91 0·94 0·92 F 0·20 0·28 0·27 0·26 0·19 0·21 0·25 0·26 0·22 0·25 H2O 2·57 2·43 2·69 2·30 2·39 2·51 0·71 0·67 0·20 1·26 Total 98·12 97·95 95·85 98·63 96·52 96·58 98·67 96·99 99·06 99·27 Table 2: Major and volatile element analyses of representative Campi Flegrei glasses Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Analysis #: CF195_cp x113_m6 CF195_cp x64_m1 CF195_cp x86_m2 CF195_cp x86_m3 CF195_cp x110_m1 CF195_cp x113_m7 CF195_cp x122_m1 CF195_cp x122_m2 CF195_cp x123_m3 CF195_cp x137_m5 Type: mi mi mi mi mi mi mi mi mi mi SiO2 58·77 57·35 57·81 56·19 58·05 57·63 58·35 58·26 59·68 58·71 Na2O 4·45 4·04 4·11 3·94 5·04 4·65 4·20 4·08 5·03 4·42 MgO 0·55 0·77 0·75 0·74 0·76 0·59 0·87 0·81 0·51 0·70 Al2O3 18·17 17·70 18·27 17·26 16·54 18·02 18·03 18·12 16·97 17·71 K2O 8·40 8·57 8·49 7·89 6·86 8·37 8·48 8·94 7·43 8·42 CaO 2·22 2·59 2·55 2·48 2·72 2·26 2·81 2·83 2·33 2·24 TiO2 0·43 0·48 0·48 0·42 0·55 0·46 0·50 0·44 0·53 0·49 MnO 0·09 0·09 0·11 0·15 0·19 0·08 0·10 0·12 0·12 0·11 FeOt 3·31 3·82 3·46 3·39 3·96 3·38 3·83 3·66 3·85 3·37 P2O5 0·08 0·15 0·13 0·14 0·08 0·12 0·13 0·13 0·10 0·11 Cl 0·95 0·66 0·73 0·64 0·85 0·84 0·67 0·66 0·94 0·77 F 0·25 0·22 0·23 0·22 0·22 0·28 0·25 0·22 0·23 0·28 H2O 2·82 3·48 2·84 5·56 3·47 2·45 2·44 1·04 2·28 2·54 Total 100·47 99·93 99·96 99·01 99·29 99·12 100·67 99·31 100·01 99·87 Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Astroni 1 Astroni 1 Astroni 1 Analysis #: CF195_cp x159_m4 CF195_cp x188_m1 VF55_cf19 5_1_1 VF55_cf19 5_2_1 VF55_cf19 5_3_1 VF55_cf19 5_4_1 VF55_cf19 5_4_2 CF69_cp x22_m1 CF69_cp x23_m2 CF69_cp x55_m1 Type: mi mi mg mg mg mg mg mi mi mi SiO2 57·83 58·59 56·50 57·19 58·62 57·66 57·48 57·70 59·17 56·74 Na2O 4·85 4·77 6·88 7·88 7·56 7·69 7·29 4·39 4·25 4·26 MgO 0·66 0·68 0·21 0·25 0·28 0·17 0·18 0·65 0·42 0·54 Al2O3 17·10 17·52 18·28 18·79 19·04 18·69 18·87 17·90 17·84 18·07 K2O 7·18 8·25 6·88 7·23 7·25 7·20 7·30 8·08 8·36 8·89 CaO 2·59 2·52 1·81 1·51 1·66 1·69 1·75 2·47 2·19 2·17 TiO2 0·50 0·47 0·49 0·50 0·39 0·45 0·43 0·45 0·49 0·41 MnO 0·20 0·13 0·24 0·37 0·20 0·20 0·28 0·10 0·19 0·04 FeOt 3·91 3·38 3·08 3·30 2·74 2·89 3·19 3·36 3·65 3·15 P2O5 0·15 0·11 0·01 0·00 0·00 0·05 0·07 0·12 0·10 0·08 Cl 0·89 0·78 0·90 0·97 0·97 1·05 1·17 0·96 1·00 0·87 F 0·24 0·32 1·21 0·65 0·73 0·82 0·68 0·28 0·28 0·26 H2O 3·71 2·38 0·88 0·76 0·97 1·06 1·08 2·37 2·22 2·12 Total 99·80 99·88 97·36 99·41 100·41 99·60 99·77 98·82 100·15 97·60 Eruption: Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Analysis #: CF69_cpx 55_m2 CF69_cpx 66_m1 CF69_cpx 66_m3 CF69_cpx 82_m1 CF69_cpx 91_m1 CF69_cpx 92_m1 CF69_cpx 97_m3 CF69_cpx 113_m1 CF69_cpx 116_m1 CF69_cpx 127_m1 Type: mi mi mi mi mi mi mi mi mi mi SiO2 56·99 54·97 56·56 56·78 58·21 57·38 57·73 56·74 56·44 56·55 Na2O 4·52 4·15 4·02 4·20 4·60 4·35 4·46 4·76 3·65 4·22 MgO 0·53 0·61 0·72 0·50 0·51 0·76 0·54 0·55 0·78 0·58 Al2O3 17·82 17·60 18·24 17·90 17·67 18·60 17·91 17·51 18·40 17·65 K2O 8·50 8·55 8·83 8·35 8·37 8·44 8·27 8·57 8·84 8·28 CaO 2·15 2·43 2·62 2·07 2·03 2·47 2·34 2·17 2·37 2·34 TiO2 0·44 0·47 0·47 0·45 0·48 0·41 0·45 0·45 0·51 0·45 MnO 0·13 0·09 0·12 0·19 0·20 0·11 0·12 0·15 0·02 0·10 FeOt 3·37 3·76 4·20 3·40 3·40 2·85 3·38 3·19 3·27 3·84 P2O5 0·10 0·14 0·13 0·13 0·08 0·17 0·08 0·08 0·15 0·15 Cl 0·93 0·75 0·69 0·91 1·03 0·84 0·90 0·93 0·73 0·82 F 0·25 0·21 0·23 0·28 0·31 0·30 0·25 0·25 0·22 0·20 H2O 2·56 2·21 2·58 2·29 2·27 2·21 2·00 2·62 2·33 2·51 Total 98·28 95·94 99·41 97·46 99·16 98·90 98·43 97·97 97·71 97·70 Eruption: Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Astroni 1 Analysis #: CF69_cpx 127_m3 CF69_cpx 130_m1 CF69_cpx 138_m2 CF69_cpx 156_m2 CF69_cpx 182_m1 CF69_cpx 182_m2 VF55_cf69 _2_1 VF55_cf69 _3_1 VF55_cf69 _5_1 VF55_cf69 _6_1 Type: mi mi mi mi mi mi mg mg mg mg SiO2 57·17 56·80 55·39 58·52 55·35 55·59 59·14 57·69 59·43 58·83 Na2O 4·07 4·51 4·62 4·56 3·76 3·87 3·90 4·38 4·67 4·50 MgO 0·54 0·55 0·42 0·45 0·71 0·77 0·54 0·50 0·49 0·58 Al2O3 17·63 17·67 17·09 17·12 17·52 17·53 18·37 17·85 18·09 18·11 K2O 8·36 8·37 8·48 8·03 8·53 8·48 8·61 8·47 8·44 8·56 CaO 2·31 2·30 2·01 2·23 2·64 2·70 2·29 2·28 2·45 2·36 TiO2 0·49 0·51 0·40 0·48 0·48 0·50 0·48 0·42 0·46 0·37 MnO 0·14 0·11 0·13 0·16 0·12 0·17 0·16 0·17 0·16 0·07 FeOt 3·60 3·40 3·34 3·53 3·90 3·39 3·27 3·31 3·42 3·41 P2O5 0·16 0·10 0·06 0·09 0·20 0·12 0·04 0·09 0·09 0·05 Cl 0·88 0·93 0·97 0·91 0·74 0·73 0·91 0·91 0·94 0·92 F 0·20 0·28 0·27 0·26 0·19 0·21 0·25 0·26 0·22 0·25 H2O 2·57 2·43 2·69 2·30 2·39 2·51 0·71 0·67 0·20 1·26 Total 98·12 97·95 95·85 98·63 96·52 96·58 98·67 96·99 99·06 99·27 Eruption: Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Monte Nuovo Analysis #: CF195_cp x113_m6 CF195_cp x64_m1 CF195_cp x86_m2 CF195_cp x86_m3 CF195_cp x110_m1 CF195_cp x113_m7 CF195_cp x122_m1 CF195_cp x122_m2 CF195_cp x123_m3 CF195_cp x137_m5 Type: mi mi mi mi mi mi mi mi mi mi SiO2 58·77 57·35 57·81 56·19 58·05 57·63 58·35 58·26 59·68 58·71 Na2O 4·45 4·04 4·11 3·94 5·04 4·65 4·20 4·08 5·03 4·42 MgO 0·55 0·77 0·75 0·74 0·76 0·59 0·87 0·81 0·51 0·70 Al2O3 18·17 17·70 18·27 17·26 16·54 18·02 18·03 18·12 16·97 17·71 K2O 8·40 8·57 8·49 7·89 6·86 8·37 8·48 8·94 7·43 8·42 CaO 2·22 2·59 2·55 2·48 2·72 2·26 2·81 2·83 2·33 2·24 TiO2 0·43 0·48 0·48 0·42 0·55 0·46 0·50 0·44 0·53 0·49 MnO 0·09 0·09 0·11 0·15 0·19 0·08 0·10 0·12 0&