Table 1: Summary of petrographic characteristics for porphyritic samples from Campbell and Chatham islands, New Zealand phenocrysts sample location

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1 Table 1: Summary of petrographic characteristics for porphyritic samples from Campbell and Chatham islands, New Zealand phenocrysts sample location deposit type rock type age/unit >5% <5% other % total texture OU36163 Campbell Is. lava subalk ~7 pl ol>cpx mt 24 p, hc, tc OU36173 Campbell Is. lava trans bas ~7 pl cpx>ol mt 21 p, hc, tc OU39771 Campbell Is. dike trans bas ~7 pl cpx mt 13 p, hc Chatham Island CHT-1 Ohira Bay lava akb ps - ol>cpx mt 2 fp, hc, tc CHT-3 Ohira Bay Quarry lava akb ps - ol>cpx mt 2 fp, hc CHT-4 Owenga Rd. lava basalt ps - ol~cpx>pl mt 1 mp, hphy, amg CHT-5 Cape Young lava basanite mr ol cpx~amp mt 11 p, hpc, amg CHT-8 Cape Young lava basanite mr cpx>amp ol mt 13 p, hpc, amg CHT-9 Mairangi block trans bas kn ol cpx - 7 mp, hpc, tc CHT-10 Mt. Chudleigh plug basanite kn - ol>cpx mt 5 hphy CHT-11 Mt. Chudleigh lava basanite kn ol cpx - 6 fp, hpc CHT-12 Waitaha Creek lava trans bas ps - ol~cpx mt 8 mp, hc CHT-14 Korako Hill block BTA kn pl>cpx ol mt 26 mp, vtph, amg CHT-15 Matakitaki tuff basalt kn ol~cpx - mt 15 vtph, palg CHT-16 Maunganui lava tephrite mr - ol - 1 hphy CHT-17 Maunganui lava tephrite mr - ol>cpx>amp mt 6 fp, hpc, v CHT-18 West Rd. Quarry lava akb kn - cpx>ol - 7 fp, hpc, v CHT-19 Tawreikoko dike basalt mr - cpx>ol>pl mt 6 hpc, v, amg CHT-20 Tawreikoko dike basanite mr ol~cpx amp mt 20 p, hpc, amg CHT-21 Tuku River lava trans bas ps ol~cpx pl mt 13 fp, hc CHT-22 Tuku River lava trans bas ps - ol>cpx mt 7 fp, hc, tc CHT-23 Tuku River lava trans bas ps ol cpx - 10 fp, hc CHT-24 Tuku River lava trans bas ps cpx>ol - mt 12 fp, hc CHT-25 Tuku River lava trans bas ps cpx>ol pl mt 14 fp, hc, tc CHT-26 Tuku River lava trans bas ps - cpx>ol>pl mt 5 fp, hc CHT-27 Cape Fournier lava trans bas ps cpx>ol - mt 11 fp, hc abbreviations: ps - late Cretaceous Southern Volcanics; kn - Eocene Northern Volcanics; mr - Pliocene Rangitihi Volcanics. akb - alkali basalt; BTA - basaltic trachyandesite; trans bas - transitional basalt; subalk - subalkali basalt. Phenocrysts: pl - plagioclase; ol - olivine; cpx - clinopyroxene; amp - amphibole; mt - magnetite. Texture: p - porphyritic; fp - finely porphyritic (phenocrysts <5mm); mp - microporphyritic; v - vesicular (>10%); amg - amygdaloidal; hc - holocrystalline; hpc - hypocrystalline; hphy - hypohyaline; vtph - vitrophyric; palg - palagonitized; tc - trachytic

2 Table 2: Major and trace elements compositions of Chatham Island (CHT), Campbell Island (OU) and Antipodes Island (ANT) basalts sample CHT-1 CHT-3 CHT-5 CHT-8 CHT-9 CHT-10 CHT-11 CHT-12 CHT-14 CHT-16 CHT-17 CHT-18 CHT-20 CHT-21 CHT-22 CHT-23 CHT-24 CHT-25 CHT-26 rock type akb akb basanite basanite trans bas basanite basanite trans bas BTA tephrite tephrite akb basanite trans bas trans bas trans bas trans bas trans bas trans bas unit ps ps mr mr kn kn kn ps kn mr mr kn mr ps ps ps ps ps ps age (Ma) SiO TiO Al 2 O FeO t MnO MgO CaO Na 2 O K 2 O P 2 O LOI orig. sum Mg# Olivine % ne hy ol Q Sc V Cr Ni Cu Zn Ga Rb Sr Y Zr Nb Cs Ba La Ce Nd Sm Eu Tb Yb Lu Hf Ta Pb Th U Chatham units: ps, Southern Volcanics; kn, Northern Volcanics; mr, Rangitihi Volcanics (Grindley et al. (1977). Chatham ages (Ma) determined by the 40 Ar/ 39 Ar method (Table 3). Ages for the Campbell and Antipodes Islands are from Morris (1984), Adams et al. (1979) and Cullen (1969). Major (wt.%) and trace elements (ppm) are normalized to 100% anhydrous with total Fe as FeO(FeO t = 0.9 Fe 2 O 3 ). CIPW values for ne, hy, ol and Q are weight normative. LOI is the weight% loss of sample powder on ignition at 1000 C for 2 hrs. Mg# is the atomic percent Mg 2+ /(Mg 2+ +Fe 2+ ) and Olivine is the percent of equilibrium olivine added incrementally to bring Mg# to 73. Akb, alkali basalt; trans bas, transitional basalt; BTA, basaltic trachyandesite; subalk, subalkali basalt (see text for classification details). Pb values with 2 signficant figures by isotope dilution with precision ±1-2% by ICP-MS. Other Pb values measured by XRF (1 significant figure) with precisions of ±10%.

3 Table 2: continued sample CHT-27 OU36163 OU36173 OU36181 OU39737 OU39796 ANT3 ANT7 ANT13 ANT16 rock type trans bas subalk trans bas subalk Q gabbro trans bas basanite tephrite basanite basanite unit ps age (Ma) SiO TiO Al 2 O FeO t MnO MgO CaO Na 2 O K 2 O P 2 O LOI orig. sum Mg# Olivine % ne hy ol Q Sc V Cr Ni Cu Zn Ga Rb Sr Y Zr Nb Cs Ba La Ce Nd Sm Eu Tb Yb Lu Hf Ta Pb Th U

4 Table 3: Summary of 40 Ar/ 39 Ar data for Chatham Island basalts. Preferred ages underlined. Total gas Plateau Isochron sample locality rock type sample age (Ma) ± 2 σ age (Ma) ± 2 σ n MSWD 39 Ar, % K/Ca age (Ma) ± 2 σ MSWD 40 Ar/ 36 Ar ± 2 σ CHT-1 Ohira Bay akb gm CHT-3 Ohira Bay quarry akb gm CHT-5 Cape Young bas amp CHT-8 Cape Young bas amp CHT-11 Mt. Chudleigh bas gm CHT-12 Waitaha Creek akb gm CHT-17 Maunganui bas gm CHT-20 Tawreikoko akb gm CHT-20 Tawreikoko akb amp CHT-21 Tuku River akb gm CHT-22 Tuku River akb gm CHT-25 Tuku River akb gm CHT-27 Cape Fournier akb gm Abbreviations: akb - alkali basalt, bas - basanite, gm - groundmass, amp - amphibole (kaersutite). number of apparent ages included in the mean plateau age calculation. value of y-intercept on inverse isochron plots. Measurements were made using a Mass Analyzer Products mass spectrometer operated in electron multiplier mode with an overall sensitivity of approximately 3.0 x moles/pa. Samples were step-heated in a double-vacuum molybdenum resistance furnace. Typical blanks including mass spectrometer backgrounds were; 171, 4, 0.1, 0.8, 0.8 x moles at masses 40, 39, 38, 37 and 36, respectively. J-factors were determined to a precision of 0.10% by analyzing 4 single-crystal aliquots from each of 4 to 6 radial positions around each Al irradiation tray. Corrections for interfering nuclear reactions were determined using K-glass and CaF 2. These values are ( 40 Ar/ 39 Ar)K = ± , ( 36 Ar/ 37 Ar)Ca = ± and ( 39 Ar/ 37 Ar)Ca = ± All errors are reported at the 2σ confidence level. Decay constant and isotopic abundances follow Steiger & Jager (1977).

5 Table 4: Sr, Nd and Pb Isotope data for Chatham, Antipodes and Campbell Islands, New Zealand sample Age (Ma) 87 Rb/ 86 Sr 87 Sr/ 86 Sr (initital) model source 147 Sm/ 144 Nd 143 Nd/ 144 Nd (initital) εnd(t) model source 206 Pb/ 204 Pb (initial) model source 207 Pb/ 204 Pb (initial) 208 Pb/ 204 Pb (initial) μ ω к Chatham Island CHT ±15 ( ) ±09 ( ) (20.307) (15.712) (39.725) CHT ±16 ( ) ±10 ( ) (20.411) (15.716) (39.746) CHT ±19 ( ) ±11 ( ) (20.417) (15.655) (40.116) CHT ±16 ( ) ±10 ( ) (20.318) (15.646) (39.977) CHT ±16 ( ) ±11 ( ) (19.608) (15.640) (39.544) CHT ±18 ( ) ±10 ( ) (19.980) (15.727) (39.443) CHT ±21 ( ) ±10 ( ) (20.628) (15.679) (40.449) CHT ±24 ( ) ±10 ( ) (20.305) (15.619) (40.046) CHT ±19 ( ) ±11 ( ) (20.204) (15.718) (39.723) CHT ±21 ( ) ±10 ( ) (20.252) (15.680) (39.476) CHT ±18 ( ) ±10 ( ) (20.079) (15.673) (39.553) CHT ±21 ( ) ±11 ( ) (20.017) (15.717) (39.552) Antipodes and Campbell Island ANT ±20 ( ) ±10 ( ) (20.604) (15.693) (39.894) ANT ±17 ( ) ±11 ( ) (20.528) (15.657) (39.723) ANT ±15 ( ) ±10 ( ) (20.485) (15.651) (39.700) OU ±16 ( ) ±10 ( ) (19.167) (15.664) (39.147) OU ±21 ( ) ±10 ( ) (19.067) (15.628) (38.858) OU ±16 ( ) ±10 ( ) (19.290) (15.603) (39.041) Element concentrations are given in Table 3 and were determined by XRF (Rb, Sr), INAA (Sm, Nd, U, Th) and isotope dilution (Pb). Sr and Nd isotope interlab standard values were for Sr (NBS 987) and for Nd (La Jolla). Errors are 2σ. Nd isotopes normalized to 146 Nd/ 144 Nd of Pb analyses were corrected using NBS981 ( 206 Pb/ 204 Pb , 207 Pb/ 204 Pb , 208 Pb/ 204 Pb , Todt et al., 1996). μ = 238 U/ 204 Pb, ω = 232 Th/ 204 Pb, and к = 232 Th/ 238 U. Source ratios were calculated using a two stage mantle evolution model. For example, the present-day 143 Nd/ 144 Nd value of the source for late Cretaceous basalts is calculated by first determining the 143 Nd/ 144 Nd of Bulk Earth at 2.5 Ga (using λ Sm = 6.54E-12, 143 Nd/ 144 Nd chur = at 4.6 Ga, and 147 Sm/ 144 Nd chur = ) and then projecting a line from this value through the initial 143 Nd/ 144 Nd ratio calculated for each sample. The intercept ( 143 Nd/ 144 Nd at t = 0 Ma) and slope ( 147 Sm/ 144 Nd) of this line are the model source values. Model source 87 Sr/ 86 Sr ratios were calculated using λ Rb = 1.42E-11, 87 Sr/ 86 Sr babi = at 4.6 Ga, and 87 Rb/ 86 Sr = Model source 206 Pb/ 204 Pb ratios using λ U = E-10, 206 Pb/ 204 Pb = at 4.6 Ga, and 238 U/ 204 Pb = Model parent/daughter ratios are for 147 Sm/ 144 Nd, for 87 Rb/ 86 Sr and for 238 U/ 204 Pb.

6 Table 5: Source concentrations for Antipodes and Chatham Island basalts ANT+CHT Southern ANT+CHT Southern Element Co (ppm) ±2σ Co (ppm) ±2σ PUM (ppm) Co/PUM Co/PUM Cs Rb Ba Th U Nb Ta K La Ce Pb Nd Sr P Zr Hf Sm Eu Ti Tb Y Yb Lu Rb/ 86 Sr Sm/ 144 Nd U/ 204 Pb Th/ 204 Pb Th/ 238 U Primitive upper mantle (PUM) values from McDonough & Sun (1995).

Chapter 9: Trace Elements

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