Sample Preparation and Analytical Methods

Sample Preparation and Analytical Methods A1. University of Massachusetts XRF Analytical Methods New XRF analyses are given in the Auxiliary Materials (ts1) with previous major-element analyses. New XRF trace element analyses are also given (and indicated in table) for samples erupted prior to 1998, when a new, more precise XRF instrument became available. Fresh pieces of quenched lava were crushed in a tungsten carbide jaw crusher to ~2 mm diameter and cleaned in a beaker with deionized water and dried in an oven at 70ºC for 24 hours to drive off excess water. Lava fragments were then powdered using a Rocklabs WC shatterbox for 1 – 2 minutes. All XRF analyses were performed at the University of Massachusetts XRF Laboratory where whole-rock, major-element abundances were measured using the procedures of Rhodes and Vollinger [2004]. One sigma accuracy and precision estimates for the XRF data are ~0.5% for major elements [Rhodes, 1988]. Five grams of a powdered sample were heated in a muffle furnace at 1020ºC for 10 minutes to limit the amount of ferrous iron formation [Rhodes and Vollinger, 2004]. The weight loss is LOI. Major elements were measured on a fused La-bearing lithium borate glass disc using a Siemens MRS-400 spectrometer with a Rh X-ray tube operating at 2700 W (the voltage was 45 kV and 60mA and the count times were 200 seconds). Trace element concentrations (Rb, Sr, Ba, La, Ce, Nb, Zr, Y, Zn, Ga, Ni, Cr, V) were measured on a separate powder pellet using a Philips PW2400 sequential spectrometer with a Rh X-ray tube operating at 3000 W (the voltage was 60kV and 50mA and 2.5 hour total count time). Precision and accuracy estimates for the trace element data are described by Rhodes [1996] and Rhodes and Vollinger [2004]. Results for each sample are the average of two separate analyses (2 disks for one sample) for major elements, but one analysis (one pellet run once) for trace elements. A summary of XRF trace element values of USGS standards analyzed with lavas from Kīlauea’s Pu‘u ‘Ō‘ō eruption since 2002 are given in the Auxiliary Materials (ts3).

A2. PCIGR and SDSU Trace Element and Isotopic Analytical Methods Forty-one Pu‘u ‘Ō‘ō lava samples from 1983 to 1999 were selected for Pb and Sr isotopic analysis at the Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia (UBC; Table 2). The analytical methods for thirteen additional Pb isotopic analyses of Pu‘u ‘Ō‘ō lavas collected between 2006 and 2010, and fourteen analyses from Marske et al. [2008] that are used in this study, are described in Marske et al. [2007] (samples

1 are indicated in Table 2). Thirteen samples without trace-element data were selected for high- precision trace-element analysis and results are shown in Auxiliary Materials (ts2) with previous trace-element analyses for Pu‘u ‘Ō‘ō lavas (corrected data is also shown, as described in table caption). Isotopic ratios of Pb for these samples were measured with a Nu Plasma (Nu Instruments) 1700 Multiple Collector-Inductively Coupled Plasma-Mass Spectrometer (MC- ICP-MS) at San Diego State University (SDSU). Sr isotopic ratios for 1998-2005 lava samples from Marske et al. [2008] were measured using a VG Sector 54 thermal ionization mass spectrometer (TIMS) at SDSU. Lava samples from 2006 to 2010 were analyzed for Sr isotopic ratios at the PCIGR, according the the methods described below.

Samples were prepared for trace-element analysis at the PCIGR by the technique described by Pretorius et al. [2006] and Carpentier et al. [2013] on unleached lava fragments. Lava fragments <2 mm in diameter (~100 mg) were weighed in 7 mL screw-top Savillex® beakers and dissolved in 1 mL ~14N HNO3 and 5 mL 48% HF on a hotplate for 48 hours at 130ºC with periodic ultrasonication. Samples were dried and redissolved in 6 mL 6N HCl on a hotplate for 24 hours and then dried and redissolved in 1 mL concentrated HNO3 for 24 hours before final drying. Trace element abundances were measured with a Thermo Finnigan Element2 High Resolution- Inductively Coupled Plasma-Mass Spectrometer (HR-ICP-MS) within 24 hours of redissolution, following the procedures described by Pretorius et al. [2006] and Carpentier et al. [2013]. High field strength elements (HFSE) and large ion lithophile elements (LILE) were measured in medium resolution mode at 2000x dilution using a PFA teflon spray chamber washed with Aqua Regia for 3 minutes between samples. Rare earth elements (REE) were measured in high resolution mode, and U and Pb in low resolution mode, at 2000x dilution using a glass spray chamber washed with 2% HNO3 between samples. Total procedural blanks and reference material (Kil93) was analyzed with the batch of samples. Indium was used as an internal standard in all samples and standard solutions. Background and standard solutions were analyzed after every 5 samples to detect memory effects and mass drift.

For isotope chemistry at PCIGR, fresh pieces of crushed lava (<2mm diameter; ~0.6-0.8 g total) were carefully picked using a binocular microscope to avoid signs of post-eruptive alteration.

2 Each sample was ultra-sonicated (15 minutes) and rinsed three times in ultra-pure water in a clean Savillex® beaker prior to rinsing with room temperature 0.5 M HBr for 15 seconds to remove any surface contamination. The sample was washed again in ultra-pure water, dried, and weighed. Sample digestion for purification of Pb and Sr by column chemistry involved dissolving ~100-250 mg of the cleaned, crushed lava in 1 mL ~14N HNO3 and 10 mL 48% HF on a hotplate for 48 hours at 130ºC with periodic ultrasonication. Samples were dried and redissolved in 6 mL 6N HCl on a hotplate for 24 hours and then dried. Pb was separated and purified in two passes through anion exchange columns and the discard was used for Sr separation. Detailed procedures for column chemistry for separating Pb and Sr at the PCIGR are described in Weis et al. [2006] and Nobre Silva et al. [2009]. Sr isotope ratios were measured on a Thermo Finnigan Triton Thermal Ionization Mass Spectrometer (TIMS) in static mode with relay matrix rotation on a single Ta and double Re-Ta filament, respectively. Four to 5 filaments per barrel of 21 were occupied by standard NIST SRM 987 for each barrel where samples were run. Sample Sr isotopic compositions were corrected for mass fractionation using 86Sr/88Sr = 0.1194. Each sample was then normalized using the barrel average of the reference material relative to the values of 87Sr/86Sr = 0.710248 [Weis et al., 2006]. During the period when the samples were analyzed, the NIST SRM 987 standard gave an average of 0.710243 ± 13 (n = 18; 2σ error is reported as times 106). PCIGR internal reference material from the Kīlauea summit eruption in 1919 (Kil1919) was processed with the samples and yielded Sr isotopic ratios of 0.703468 ± 8. Twenty-six previous analyses of Kil1919 at SDSU average 0.703471 ± 13. Four chemistry duplicates of Menehune standard (an in-house glass standard collected from a Pu‘u ‘Ō‘ō lava flow of Kīlauea Volcano that was quenched on June 24, 2006), processed with the other lava samples, had Sr isotopic compositions of 0.703608 ± 7, 0.703605 ± 8, 0.703611 ± 8, and 0.703624 ± 9. Twenty-six previous analyses of Menehune standard performed at SDSU averaged 0.703617 ± 13.

Pb isotopic compositions at PCIGR were analyzed by static multi-collection on a Nu Plasma MC-ICP-MS. The detailed analytical procedure for Pb isotopic analyses at the PCIGR is described in Weis et al. [2005]. The configuration for Pb analyses allows for collection of Pb, Tl, and Hg together. Tl and Hg are used to monitor instrumental mass discrimination and isobaric overlap, repectively. All sample solutions were analyzed with approximately the same Pb/Tl

3 ratio (~4) as the reference material NIST SRM 981. To accomplish this, a small aliquot of each sample solution from the Pb columns was analyzed on the Nu Plasma to determine the amount of Pb available. The SRM 981 standard was run after every two samples on the Nu Plasma. During the time samples were run, analyses of the SRM 981 Pb reference material gave values of 206Pb/204Pb = 16.9430 ± 19, 207Pb/204Pb = 15.4997 ± 18, and 208Pb/204Pb = 36.7221 ± 58 (n = 38; 2σ error is reported as times 104); these values are in excellent agreement with reported TIMS triple- spike values of Galer and Abouchami [1998]. Results were further corrected by the sample- standard bracketing method described by White et al. [2000]. Reference material Kil1919

206 204 207 204 analyzed at PCIGR yielded Pb isotopic ratios of Pb/ Pb = 18.6556 ± 8, Pb/ Pb = 15.4924 ± 8, and 208Pb/204Pb = 38.2148 ± 21. Thirty-three analyses of Kil1919 performed at SDSU over

206 204 207 204 the course of this study averaged Pb/ Pb = 18.6552 ± 27, Pb/ Pb = 15.4897 ± 20, and 208Pb/204Pb = 38.2068 ± 57. Four chemistry duplicates of Menehune standard analyzed at PCIGR

206 204 207 204 208 204 averaged Pb/ Pb = 18.4062 ± 28, Pb/ Pb = 15.4724 ± 26, and Pb/ Pb = 38.0662 ± 59. Sixty-eight previous analyses of Menehune standard performed at SDSU over the course of this

206 204 207 204 208 204 study averaged Pb/ Pb = 18.4073 ± 16, Pb/ Pb = 15.4714 ± 18, and Pb/ Pb = 38.0627 ± 60.

A3. Glass and matrix oxygen isotopes Glass and holocrystalline matrix material were separated from Pu‘u ‘Ō‘ō lavas by hand picking from coarsely crushed but otherwise untreated samples. Oxygen isotope compositions of c. 2 mg aliquots of these separates were determined by laser fluorination, using a 50W CO2 laser and

BrF5 as reagent [Sharp, 1990; Valley et al., 1995]. Product O2 was converted to CO2 by reaction with hot graphite; CO2 was then analyzed for its isotopic composition by dual-inlet gas source mass spectrometry on a Thermo Finnegan Delta XL gas source isotope ratio mass spectrometer at California Institute of Technology. Data are reported in units of per mil versus the VSMOW standard. Analyses were standardized by comparison with measurements of Gore Mountain garnet standard [Valley et al., 1995]. This standard was analyzed between two and five times each day of analyses, and the data for unknowns analyzed on that day were corrected by the average difference between measured and accepted values for that standard. The external precision of repeat measurements of separate splits of unknown samples averaged 0.05‰ (1σ). Seven analyses of Gore Mtn. Garnet were run concurrently with these samples, with a standard

4 deviation of ±0.06 ‰ (1σ; averaged over all days). This is comparable with the typical external precision for replicate measurements of silicate standards for this laboratory and technique [e.g., Bindeman et al., 2006; Eiler et al., 1995; Eiler et al., 1996], suggesting that the glass separates analyzed in this study are homogeneous in δ18O at the scale of c. 2 mg aliquots. The results

18 reported here are relative to δ OVSMOW [Coplen, 1988]. Four analyses of Menehune standard performed with the other Pu‘u ‘Ō‘ō lavas yielded 5.22 ± 0.03 ‰ (1σ).

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