U-Series Isotopic Constraints on Mantle Upwelling on the Periphery of the Hawaiian Plume Isotope Geochemistry of Haleakala Crater Basanites Erin H

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U-series isotopic constraints on mantle upwelling on the periphery of the Hawaiian plume Isotope geochemistry of Haleakala crater basanites Erin H. Phillips and Kenneth W.W. Sims, University of Wyoming, and Vincent J.M. Salters, Florida State University 1. Introduction 2. Major and Trace Element Geochemistry and Long-lived Radiogenic Isotopes

100 400 ● The Hawaiian islands are part of the age progressive series of 16 Comparison to Haleakala Crater (this study) 90 global alkaline volcanoes that form the Hawaiian-Emperor seamount chain. At 14 Haleakala SW Rift Zone (Sims et al., 1999) 300 suites Haleakala, on the island of Maui, basanitic lavas of the Hana Haleakala post-shield 80 12 Haleakala shield 200 Volcanics represent end-member rejuvenated stage alkaline 70 Kilauea magmatism (Clauge, 1987). Although shield-stage tholeiitic 100 10 Mauna Loa 60

volcanism predominates in the Hawaiian islands, alkaline lavas O 2 Mauna Kea 0 erupted on the trailing edge of the Hawaiian plume present an 8 Hualalai trachytes 50 O+Na important component to understanding mantle melting and solid 2 Loihi

K 40 6 Nyiragongo mantle upwelling. Averages for 30 Leucite Hills lamproites Hawaiian Lavas 4 Ross Island, Antarctica basanites 20 ● We present geochemical data for 13 samples from Haleakala Samoa crater. 14C ages for seven samples range from 870 ± 40 to 4070 ± 50 2 See supplement for full reference list 10 years (Sherrod and McGeehin, 1999). Preliminary data for 5 0 1995) Mantle (McDonough and Sun, Sample/Primitive 0 samples from the Haleakala southwest rift zone (Sims et al., 1999) 35 40 45 50 55 60 65 Rb Ba Th U Nb La Ce Sr Pb Nd Sm Hf Eu Dy Y Yb Lu SiO are consistent with iso-viscous (Watson and McKenzie, 1991) and 2

thermo-viscous (Hauri et al., 1994) ﬂuid mechanical models of 10 plume upwelling in which upwelling rates are slower on the Hawaiian Lavas periphery of plume. 9 8 ● Haleakala crater and SW rift zone basanites have lower SiO and higher alkali contents and exhibit an enrichment Kauai Hawaiian Islands 7 2 Rejuvenated stage Nd in incompatible trace elements compared to other young ε Hana Volcanics Oahu 6 Hawaiian lavas (above). 5 Maui 20 4 ● Haleakala basanites fall within the global range of major West Hualalai Maui Volcano Mauna Kea and trace element compositions for alkaline volcanic rocks 15 DMM 3 Kilauea 0.7030 0.7032 0.7034 0.7036 0.7038 0.7040 0.7042 and do not deﬁne an extreme alkaline end member. For 87Sr/86Sr Haleakala 10 km Hawaii Loihi example, compare the trace element pattern for Haleakala 10 Mauna Loa basanites with Nyiragongo lavas (above).

Haleakala SW Nd ε 5 ● In comparison with other young Hawaiian lavas, Rift Zone HIMU Pacific MORB Haleakala basanites exhibit higher εNd (and εHf) and lower 156º15' 156º12'30'' 156º10' 156º07'30'' 0 OIB 87Sr/86Sr values, implying a greater contribution from a Ko’olau Gap EM2 Mantle Endmembers Haleakala Crater depleted source in these late-stage alkaline magmas (left). -5 20º45' EM1 970±50 940±40 870±40 1,870±40 HK-029 HK-026 1,040±40 -10 0.701 0.702 0.703 0.704 0.705 0.706 0.707 0.708 0.709 0.710 HK-028 87Sr/86Sr 1,160±50 HK-017 20º42'30'' HK-016 HK-018 1 km ō Gap 4. Upwelling Velocity and Porosity of the Melt Zone 4,070±50 Kaup Ages of lava flows and vents. Vents shown stippled. Kilauea and Mauna Loa Tholeiites* Hualalai Alkali Basalts Haleakala Basanites 0-1,100 years 3,000-5,000 years 50 km melt column; 15% melting 10 km melt column; 3% melting 10 km melt column; 3% melting 1,000-3,000 years older than 5,000 years 100 10 10

1.274 1.256 1.019

1.116 10 1.147 1.629

1.485 1.244 elocity (cm/yr) 3. U-series Isotopes 1.131 1 1 elocity (cm/yr) V elocity (cm/yr) V V

2.0 Γ=1E-5 1 Batch melting, garnet lherzolite 2.1 Φ=0.1% elling elling Accumulated fractional melting, elling

garnet lherzolite Γ=5E-5 Up w Up w 1.8 Up w 1.9 0.1 0.1 0.1 D =0.02; D =0.04 Nd Sm Φ=0.2% 0.1% 1% 10% 0.1% 1% 0.1% 1% (McKay, 1989; Salters et al, 2002) * Includes data from Porosity Porosity Porosity 1.6 DU=0.0052; DTh=0.0026

U) (Salters and Longhi, 1999) 1.7 Pietruszka et al. (2001), Γ=1E-4 230 238 230 238 230 238 238 ( Th/ U) n = 21 ( Th/ U) n = 10 ( Th/ U) n = 18 Cohen et al. (1996), and 226 230 226 230 226 230 U) Th/ ( Ra/ Th) n = 18 ( Ra/ Th) n = 10 ( Ra/ Th) n = 18 1.4 Cohen and O’Nions 235 230 231 235 231 235 231 235 ( 1.5 ( Pa/ U) n = 4 ( Pa/ U) n = 3 ( Pa/ U) n = 7

Pa/ (1993).

231 Γ=2E-4

1.2 ( Sims et al., 1999 inverted D values (shown in models above) 1.3 Φ=0.5% Lines of constant Maximum porosity 0.5-0.7% 0.2-0.3% 0.2-0.3% 1.0 Γ=5E-4 porosity (Φ) Solid mantle upwelling velocity 20-40 cm/yr approx. 2 cm/yr 0.7-0.9 cm/yr 1.1 Lines of constant Salters and Longhi, 1999 D values 0.5 0.6 0.7 0.8 0.9 1.0 Γ=1E-3 Φ=2% melting rate (Γ; Maximum porosity 2-3% (25% melting) approx. 1% approx. 1% alpha Sm/Nd kg m-3yr-1) Solid mantle upwelling velocity 30-80 cm/yr (25% melting) 4-8 cm/yr approx. 1 cm/yr Haleakala Crater (this study) Lundstrom et al., 1994 D values Haleakala SW Rift Zone (Sims et al., 1999) Maximum porosity 1-2% approx. 0.6% no convergence 1.7 Kilauea (Sims et al., 1999) Γ=1E-5 Solid mantle upwelling velocity 20-50 cm/yr approx. 2 cm/yr no convergence Γ=1E-4 Γ=5E-5 Kilauea (Pietruszka et al., 2001) Γ=2E-4 Φ=0.1% Mauna Loa (Sims et al., 1999) 1.5 Γ=5E-4 ● Chromatographic porous ﬂow modeling ● All models utilize D values for a garnet Mauna Loa (Cohen et al., 1996) Γ=1E-3 (Spiegelman, 2000) shows that solid mantle peridotite source. D values for a garnet

Mauna Kea (Sims et al., 1999) Th) 1.3 Φ=0.2%

230 upwelling velocities and porosities on the pyroxenite source from Elkins et al. (2008) Hualalai (Sims et al., 1999 and this study) Loihi (Sims et al., 1999) Ra/ periphery of the Hawaiian plume are did not converge on a unique solution for 226 1.1 Nyiragongo ( Φ=0.5% lower than at the plume center. any of the compositions. Φ=2% Azores 0.9 Mt. Erebus, Antarctica Samoa 5. Conclusions Lanzarote, Canary Islands 0.7 Grande Comore 0.5 ● New data from Haleakala crater basanites reveal that these lavas result from a small degree of See supplement for full reference list 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 partial melting. Their depleted isotopic signature suggests that a MORB-like component mixed 230 238 ( Th/ U) with plume source material to produce these alkaline lavas.

230 238 ● Haleakala lavas exhibit higher ( Th/ U) than other Hawaiian lavas, ● U-series isotopes shed light on Hawaiian plume dynamics and show that solid mantle implying that they are the manifestation of a small degree of partial melting upwelling rates and porosities on the periphery of the plume, represented by Haleakala from a source containing residual garnet (upper left). basanites, are much lower than at the center of the plume.

226 230 231 235 ● Haleakala basanites exhibit higher ( Ra/ Th) and ( Pa/ U) than shield ● Chromatographic porous flow modeling suggests that garnet peridotite is a more likely source stage tholeiites from Kilauea and Mauna Loa and fall within the global range of for Hawaiian lavas than garnet pyroxenite. Previous interpretations preclude mafic lithologies in alkaline volcanics based on U-series isotopic composition (above right). the source of Hawaiian lavas (Stracke et al., 1999), although this remains controversial (e.g., Wang and Gaetani, 2008; Sobolev et al., 2005). ● Dynamic melting models (after McKenzie, 1985) show that melting rates for -5 -4 -3 -1 Haleakala basanites are between approximately 1x10 and 1x10 kg m yr ● Haleakala crater basanites represent an end-member in the range of Hawaiian lavas, but fall with melt-zone porosity from 0.2% to 0.5%, significantly lower than shield stage within the global array of alkaline volcanism in the context of major and trace element tholeiites (above right). geochemistry and isotopic signatures.

Literature Cited (See supplement for full reference list) Pietruszka et al. (2001) Earth Planet. Sci. Lett., 186, 15-31. Acknowledgements and Further Information Sherrod and McGeehin (1999) USGS Open-File Report 99-143, 14pp. Clauge (1987) GSA Spec. Pub. no. 30, 227-252. We thank Dave Sherrod and Matthew Jull for assistance in the ﬁeld. This work was Sims et al. (1999) Geochim Cosmochim Acta, 63, 4119-4138. Cohen et al. (1996) Earth Planet. Sci. Lett., 143, 111-124. funded by NSF-EAR. The U-series Symposium conveners, the University of Sobolev et al. (2005) Nature, 434, 590-597. Cohen and O’Nions (1993) Earth Planet. Sci. Lett., 120, 169-175. Wyoming Department of Geology and Geophysics, and the Wyoming NASA Space Spiegelman (2000) UserCalc: web-based U-series calculator. Elkins et al. (2008) Earth Planet. Sci. Lett., 265, 270-286. Grant Consortium are thanked for providing travel funds to EP. Stracke et al. (1999) Geochem. Geophys., Geosyst., 1. Hauri et al. (1994) Jour. Geophys. Res., 99, 24,275-24,300. Contact Erin Phillips at [email protected] for more information. Wang and Gaetani (2008) Contrib. Min. Pet., 156, 661-678. McKenzie (1985) Earth Planet. Sci. Lett., 74, 81-91. Watson and McKenzie (1991) J. Pet., 32, 501-537.