This documentation file was generated on 07-Jul-2020 by Nicole D. Rocco ------------------- # GENERAL INFORMATION ------------------- 1. Isotopic and Geochemical Signatures of Mantle and Crustal Contributions in Rhyolites from Okataina and Taupo volcanoes, New Zealand 2. Creator Information Name:Nicole Rocco Institution:Oregon State University College, School or Department:College of Earth, Ocean, and Atmospheric Sciences Address:104 CEOAS Admin Bldg. Corvallis, OR 97331 Email:nicolerocco74@gmail.com ORCID:https://orcid.org/0000-0001-9420-073X 3. Contact Information Name:Nicole Rocco Institution:Oregon State University College, School or Department:College of Earth, Ocean, and Atmospheric Sciences Address:104 CEOAS Admin Bldg. Corvallis, OR 97331 Email:nicolerocco74@gmail.com ORCID:https://orcid.org/0000-0001-9420-073X Name:Adam J.R. Kent Institution:Oregon State University College, School or Department:College of Earth, Ocean, and Atmospheric Sciences Address:104 CEOAS Admin Bldg. Corvallis, OR 97331 Email:adam.kent@oregonstate.edu ------------------- CONTEXTUAL INFORMATION ------------------- 1. Abstract for the dataset The data here was collected at Oregon State University (major and trace elements) and New Mexico State University in order to address rhyolite petrogenesis in the Taupo Volcanic Zone (TVZ), New Zealand. Each sheet contains data for 18 eruptions from Okataina and Taupo Volcanic Centers, the two most recently active centers in the TVZ. Major element concentrations, trace element concentrations, and Pb and Sr isotopic compositions were collected for each eruption and are tabulated in individual sheets, along with standard measurements for each technique. Major and trace elements were measured in pumice glass fragments (each on the same fragments), while isotopic compositions were measured in dissolved pumice powder from the same sub-samples as the in-situ techniques. The dataset also includes a suite of previously published isotopic data for comparative purposes. 2. Context of the research project that this dataset was collected for. Silicic caldera-forming eruptions are some of the largest and most destructive volcanic eruptions known, and present significant local and global hazards. The underlying processes within crustal magma plumbing systems that lead to the accumulation and eruption of large volumes of evolved magma remain enigmatic, yet there is broad consensus that interaction between mantle-derived magmas and surrounding crust is crucial to the generation of many silicic magmas. Constraining these processes are key to understanding the evolution of caldera-forming systems. Radiogenic isotopes are well-suited for deciphering mantle versus crustal contributions given they are not affected by fractionation and most sources have unique isotopic signatures. Here we present a suite of high precision whole pumice Pb and Sr isotope measurements from two caldera-producing volcanic centers, Okataina (OVC) and Taupo (TVC), in the world’s most active and voluminous rhyolitic volcanic system, Taupo Volcanic Zone (TVZ), New Zealand. Samples were collected from the most recent caldera-forming eruptions in the two volcanic centers along with smaller yet significant eruptions over the last c. 50 ka, with the aim of investigating spatial and temporal changes throughout a caldera cycle – the caldera-forming event and the smaller yet significant eruptions that occur between them. Glass major and trace elements complement our isotopic data, and help to elucidate contributions from mantle-derived and crustal sources and bring light to temporal changes surrounding a caldera cycle. Research questions (basis for data collection): What are the mantle-derived and crustal inputs in rhyolitic magmas from the Taupo Volcanic Zone (TVZ), New Zealand? How do the magmatic systems change geochemically over time (caldera cycle) and space (between volcanic centers)? 3. Date of data collection: 07-Dec-2017 through 10-Jan-2020 4. Geographic location of data collection: Sample collection: Taupo Volcanic Zone, New Zealand Analyses: Oregon State University and New Mexico State University 5. Funding sources that supported the collection of the data: NSF GeoPRISMS award number 1654275 -------------------------- SHARING/ACCESS INFORMATION -------------------------- 1. Licenses/restrictions placed on the data: This work is licensed under a Creative Commons Attribution 4.0 International License 2. Links to other publicly accessible locations of the data: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/bk128j50s 3. Recommended citation for the data: Rocco, N.D. (2020) Isotopic and Geochemical Signatures of Mantle and Crustal Contributions in Rhyolites from Okataina and Taupo volcanoes, New Zealand (Version 1) [Dataset]. Oregon State University. https://doi.org/10.7267/nk322m552 4. Dataset Digital Object Identifier (DOI) https://doi.org/10.7267/nk322m552 -------------------------- VERSIONING AND PROVENANCE -------------------------- 1. Last modification date 07-Jul-2020 2. Was data derived from another source? Yes - Supplement 7 includes published data from the following sources: Gamble, J., Woodhead, J., Wright, I., and Smith, I., 1996, Basalt and Sediment Geochemistry and Magma Petrogenesis in a Transect from Oceanic Island Arc to Rifted Continental Margin Arc: the Kermadec—Hikurangi Margin, SW Pacific: Journal of Petrology, v. 37, p. 1523–1546, doi:10.1093/petrology/37.6.1523. Graham, I.J., Gulson, B.L., Hedenquist, J.W., and Mizon, K., 1992a, Petrogenesis of Late Cenozoic volcanic rocks from the Taupo Volcanic Zone, New Zealand, in the light of new lead isotope data: Geochimica et Cosmochimica Acta, v. 56, p. 2797–2819, doi:10.1016/0016-7037(92)90360-U. Hoernle, K., Hauff, F., van den Bogaard, P., Werner, R., Mortimer, N., Geldmacher, J., Garbe-Schönberg, D., and Davy, B., 2010, Age and geochemistry of volcanic rocks from the Hikurangi and Manihiki oceanic Plateaus: Geochimica et Cosmochimica Acta, v. 74, p. 7196–7219, doi:10.1016/j.gca.2010.09.030. McCulloch, M.T., Kyser, T.K., Woodhead, J.D., and Kinsley, L., 1994, Pb-Sr-Nd-O isotopic constraints on the origin of rhyolites from the Taupo Volcanic Zone of New Zealand: evidence for assimilation followed by fractionation from basalt: Contributions to Mineralogy and Petrology, v. 115, p. 303–312, doi:10.1007/BF00310769. Plank, T., 2014, The Chemical Composition of Subducting Sediments, in Treatise on Geochemistry, Elsevier, p. 607–629, doi:10.1016/B978-0-08-095975-7.00319-3. Price, R.C., Gamble, J.A., Smith, I.E.M., Maas, R., Waight, T., Stewart, R.B., and Woodhead, J., 2012, The Anatomy of an Andesite Volcano: a Time–Stratigraphic Study of Andesite Petrogenesis and Crustal Evolution at Ruapehu Volcano, New Zealand: Journal of Petrology, v. 53, p. 2139–2189, doi:10.1093/petrology/egs050. Price, R., Mortimer, N., Smith, I., and Maas, R., 2015, Whole-rock geochemical reference data for Torlesse and Waipapa terranes, North Island, New Zealand: New Zealand Journal of Geology and Geophysics, v. 58, p. 213–228, doi:10.1080/00288306.2015.1026832. Storey, B.C., Leat, P.T., Weaver, S.D., Pankhurst, R.J., Bradshaw, J.D., and Kelley, S., 1999, Mantle plumes and Antarctica-New Zealand rifting: evidence from mid-Cretaceous mafic dykes: Journal of the Geological Society, v. 156, p. 659–671, doi:10.1144/gsjgs.156.4.0659. -------------------------- METHODOLOGICAL INFORMATION -------------------------- Sample Collection Samples of flow and fall deposits were collected from 18 eruptions from Okataina and Taupo in and around the Bay of Plenty, Rotorua, and Taupo regions. In the TVC, we sampled from each of the subgroups (SG) within Taupo volcano: pre-Oruanui (Okaia), Oruanui, post-Oruanui dacite group (Omega Dacite), SG1, SG2, and SG3 (Unit B, Waimahia, and Taupo Plinian, respectively). The sampling goal was to represent a full caldera cycle – pre-CFE, CFE, and post-CFE eruptions – in order to observe and analyze spatial and temporal evolution in a volcanic center. In Okataina, as in the TVC, our sampling was focused around the most recent CFE, Rotoiti, and the eruptions surrounding it. There are no known eruptions immediately prior to Rotoiti, so we chose to analyze Kakapiko, a pre-Rotoiti dome deposit (c. 127 ka; personal communication from Graham Leonard to K. Cooper and D. Gravley), as a representative pre-CFE eruption. Along with these eruptions, we sampled and analyzed five eruptions from the c. 40 ka – 28 ka Mangaone SG (Unit A, Unit B/C, Maketu, Hauparu, and Mangaone; Jurado-Chichay and Walker, 2000; Smith et al., 2005), and three from the c. 25 ka to 0.7 ka Rotorua SG (Te Rere, Rotorua Upper and Lower, and Kaharoa; Smith et al., 2005). Pumice glass major and trace elements In-situ major and trace elements were measured in pumice glass fragments from the same suite of samples chosen for isotope analysis. Pumice clasts were crushed in a small tungsten carbide jaw crusher, washed in ultrapure water in an ultrasonic three times, dried for 3 days at 60° C and sieved. Ten to twelve 1 – 2 mm pieces of glass from each eruption were hand-picked, mounted in epoxy, and polished to expose glass at the surface. Glass pieces were chosen from the same subsamples analyzed for Pb and Sr isotopic compositions (see below). Major elements were measured at Oregon State University using a CAMECA SX-100 electron microprobe equipped with five wavelength-dispersive spectrometers and high-intensity dispersive crystals for high-sensitivity analysis. Analyses were performed with a 15 keV accelerating voltage, 10 nA sample current, and 10 um beam size. Counting times ranged from 20-30 s depending on the element and desired detection limit, and zero-time intercept functions were applied to mitigate the effects of alkali migration. Analyses utilized a rhyolite glass calibration standard (RHYO) that contained an average of 77.09 wt.% SiO2 over all runs. From repeat analyses of standard glass, the average relative percent uncertainties (1σ) for representative oxides were approximately 1% for SiO2 and Al2O3, 3% for K2O and Na2O, and 5% for CaO. A complete table of all measured standard concentrations and uncertainties, along with accepted values, can be found in Supplement 3. Backscatter images of each glass fragment were also taken. A suite of 31 trace elements were measured for the same glass fragments by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at Oregon State University in the Keck Collaboratory for Plasma Mass Spectrometry. Analyses were completed with a Photon Machines Analyte G2 193 ArF Excimer Laser connected to a Thermo Scientific iCAP-RQ ICP-MS, using a 50 um spot size and 7 Hz pulse rate for all glass analyses. Ablation occurred in a He atmosphere and ablated particulate was transferred to the ICP-MS using a flow rate of 0.6 L/min. Data were processed with the in-house LaserTram Visual Basic software (see Loewen and Kent, 2012, for details) using 29Si as the internal standard isotope and GSE-1G as the calibration standard. ATHO-G, BCR-2G, BHVO-2G, GSE-1G, T1-G standards were also used as secondary standards for all analyses. Whole pumice Pb and Sr isotopes Sub-samples, consisting of small pumice clasts or fragments of larger pumice clasts, for all analyses were chosen randomly to reduce bias and prepared in a uniform manner to ensure consistency. Sub-samples were washed in ultrapure (18 MΩ) water three times and dried at 60° C. Clean clasts and fragments were crushed in a clean agate mortar and pestle into a homogenized powder. The mortar and pestle were first primed with clean quartz grains and rinsed with ultrapure water and clean isopropanol between each sample to prevent contamination. Weighing, digestion, and purification were carried out in a Class 1000 metal-free clean room with ultrapure water and clean acids at Oregon State University (OSU) and New Mexico State University (NMSU). Seven of 18 samples were weighed, digested, and purified at OSU, while the remaining samples were processed at NMSU. Approximately 100 mg of each powdered sample were completely dissolved in clean Teflon beakers in 3 mL of a 2:1 mixture (5 mL of a 2:3 mixture at OSU) of double-distilled hydrofluoric and nitric acid on a hot plate for 24 hours. All samples were visually inspected for total dissolution. Strontium and Pb were then purified using 200-400 mesh AG 50W-X8 cation exchange resin and 200-400 mesh AG1-X8 anion exchange resin, respectively. Ion exchange chromatography was performed at NMSU and OSU in accordance with the methods detailed in Ramos (1992) and Weis et al. (2006), respectively. Strontium isotopes were measured on a VG Sector 54 thermal ionization mass spectrometer (TIMS) at NMSU using five Faraday collectors in multidynamic mode with 88Sr = 3.0 V and were corrected for mass fractionation using 86Sr/88Sr = 0.1194. NBS 987 standards were analyzed every ten samples (average = 0.710273; 1σ = 0.000017). The accepted value for NBS 987 is 0.710250 ± 12 from Weis et al. (2005). This value is preferable over the NIST-certified value of 0.71034 ± 26 due to improved analytical techniques and precision. No correction was necessary, as measured NBS 987 values were within uncertainty. Procedural blanks were c. 100 pg. Lead isotopes were measured on a Thermo Scientific NeptunePlus multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) at NMSU using seven Faraday collectors in static mode while monitoring 202Hg, 203Tl, and 205Tl. NBS 981 standards were measured every three samples, normalized to the averaged measured value for the first run, and corrected to 206Pb/204Pb = 16.9405 ± 0.0015, 207Pb/204Pb = 15.4963 ± 0016, and 208Pb/204Pb = 36.7219 ± 0.0044 (Galer and Abouchami, 1998). Samples from this study were corrected with sample-standard bracketing using the normalized and corrected average standard value for each run. Procedural blanks were <50 pg. --------------------- DATA & FILE OVERVIEW --------------------- 1. File List A. Filename: RoccoND Supplement 1 Pumice Glass Major Elements Short description: Major elements collected via Electron Microprobe Analysis for pumice fragments from Okataina and Taupo Volcanic Centers, Taupo Volcanic Zone, New Zealand B. Filename: RoccoND Supplement 2 Pumice Glass Trace Elements Short description: Trace elements collected via Laser Ablation Inductively Coupled Plasma Mass Spectrometry for pumice fragments from Okataina and Taupo Volcanic Centers, Taupo Volcanic Zone, New Zealand C. Filename: RoccoND Supplement 3 EMP Standards Short description: Standard data for Electron Microprobe Analysis D. Filename: RoccoND Supplement 4 LA-ICP-MS Standards Short description: Standard data for Laser Ablation Inductively Coupled Plasma Mass Spectrometry E. Filename: RoccoND Supplement 5 Whole Rock Pb Isotopes and Standards Short description: Lead isotopic ratios collected via Multicollector Inductively Coupled Plasma Mass Spectrometry for whole pumice powders (samples and standards) from Okataina and Taupo Volcanic Centers, Taupo Volcanic Zone, New Zealand F. Filename: RoccoND Supplement 6 Whole Rock Sr Isotopes and Standards Short description: Strontium isotopic ratios collected via Thermal Ionization Mass Spectrometry for whole pumice powders (samples and standards) from Okataina and Taupo Volcanic Centers, Taupo Volcanic Zone, New Zealand G. Filename: RoccoND Supplement 7 Previously Published Isotopic Data Short description: Published Pb and Sr isotopic ratio data used for comparison in thesis write-up 2. Relationship between files: Data collected or compiled for M.Sc. thesis: Isotopic and Geochemical Signatures of Mantle and Crustal Contributions in Rhyolites from Okataina and Taupo volcanoes, New Zealand ----------------------------------------- TABULAR DATA-SPECIFIC INFORMATION FOR ALL SUPPLEMENTAL FILES ----------------------------------------- For all supplements, the first column is the sample identification (name, number, or both). For supplements 5 and 6, the second column is also sample identification. Each supplemental file contains the units in the upper left box where appropriate (weight percent for major element oxides and micrograms per gram for trace elements), and all other columns represent the oxide, element, or isotopic ratio measured. All dates are in the dd-mon-yyyy format. Internal errors are represented by either sigma (standard deviation - supplements 5 and 6) or s (standard error - supplements 3 and 4). Supplement 7 contains all previously published data, full citations are listed above.