TY - JOUR
T1 - Noble gas and geochronology study of the Hana Ridge, Haleakala volcano, Hawaii; implications to the temporal change of magma source and the structural evolution of the submarine ridge
AU - Hanyu, Takeshi
AU - Johnson, Kevin T.M.
AU - Hirano, Naoto
AU - Ren, Zhong Yuan
N1 - Funding Information:
We thank the scientific party, the crews on the R/V Yokosuka and Kairei and the operation teams of submersibles Shinkai 6500 and Kaiko of JAMSTEC Hawaiian research cruises in 2001–2002. T. H. is grateful to H. Kumagai, K. Sato and J. Tamura for their help to establish a noble gas laboratory at JAMSTEC. H. Hyodo, T. Itaya, I. Kaneoka and Y. Miura are acknowledged for providing standard helium gas samples to T. H. Eight of the 40 Ar/ 39 Ar analyses reported in this paper were carried out at the Oregon Stage University Geochronology Lab, and we thank J. Huard and R. Duncan for their helpful discussions related to this work. We are also grateful to the staff of the International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University and the staff of Japan Material Testing Reactor of the Japan Atomic Energy Research Institute for the neutron irradiation of two additional samples for 40 Ar/ 39 Ar dating. We would like to thank K. Nagao, Y. Takigami, M. Morioka and H. Sumino for 40 Ar/ 39 Ar dating analyses of these samples at Radioisotope Center, University of Tokyo. Thanks are also due to Y. Tatsumi for his support and encouragement on this study. This work was supported by NSF-0408270 and this is SOEST contribution 6911(K. T. M. J.).
PY - 2007/3/15
Y1 - 2007/3/15
N2 - In order to constrain the magma sources and the structural evolution of Hana Ridge, noble gas isotope ratios and 40Ar/39Ar ages were determined for this submarine extension of the east rift zone of Haleakala volcano. 40Ar/39Ar ages of ten lavas from Hana Ridge are bimodally distributed. Three samples have ages of 1.8-1.9 Ma and seven samples have ages of 1.4-1.5 Ma. The observation of older lavas overlying younger ones in two locations suggests that growth of Hawaiian rift zones occurs endogenously by continuous intrusion of magmas and patchy resurfacing at outbreak points. The 0.5 Ma age range for submarine Hana Ridge lavas, coupled with previously published K/Ar ages of 0.97-1.1 Ma for subaerial Honomanu lavas on the Haleakala Volcano, indicates that Haleakala shield volcanism persisted for nearly 1 My. Furthermore, the new 40Ar/39Ar ages, when considered with isotopic compositions of the lavas, suggests that the source for Hana Ridge magmas gradually shifted over a period of 0.5-1.0 My. The majority of samples from the ridge have relatively uniform 3He/4He ratios between 18 and 22 Ra, which is higher than 3He/4He of subaerial Honomanu tholeiites. 20Ne/22Ne and 21Ne/22Ne ratios define linearly correlated trend that overlaps with the Loihi-Kilauea trend. He-Ne systematics of the Hana Ridge indicate that the magmas comprising most parts of the ridge were derived from a source with a primordial less-degassed mantle component. Since Hana Ridge lavas predate the subaerial Honomanu lavas, temporal decrease of 3He/4He ratios suggests that contribution of this primordial component had decreased in the magma source during establishment of Hana Ridge and Haleakala volcano. Pb-Sr isotopes demonstrate that Hana Ridge magmas are representative of the Kea component. However, such isotopic signatures associated with elevated high 3He/4He ratios precludes that the Kea component is a distinct endmember, such as recycled oceanic crust or lithospheric mantle. Alternatively, we propose that it is a common sub-component that is a mixture of Loihi endmember and recycled oceanic crust. Ne isotope ratios of the Hawaiian samples, including the Hana Ridge, show primordial signature irrespective of 3He/4He ratios. Such apparent decoupling of He and Ne isotopes may be also attributed to mixing of the Loihi component and recycled component in the mantle plume, either of which components needs to be elementally fractionated prior to mixing.
AB - In order to constrain the magma sources and the structural evolution of Hana Ridge, noble gas isotope ratios and 40Ar/39Ar ages were determined for this submarine extension of the east rift zone of Haleakala volcano. 40Ar/39Ar ages of ten lavas from Hana Ridge are bimodally distributed. Three samples have ages of 1.8-1.9 Ma and seven samples have ages of 1.4-1.5 Ma. The observation of older lavas overlying younger ones in two locations suggests that growth of Hawaiian rift zones occurs endogenously by continuous intrusion of magmas and patchy resurfacing at outbreak points. The 0.5 Ma age range for submarine Hana Ridge lavas, coupled with previously published K/Ar ages of 0.97-1.1 Ma for subaerial Honomanu lavas on the Haleakala Volcano, indicates that Haleakala shield volcanism persisted for nearly 1 My. Furthermore, the new 40Ar/39Ar ages, when considered with isotopic compositions of the lavas, suggests that the source for Hana Ridge magmas gradually shifted over a period of 0.5-1.0 My. The majority of samples from the ridge have relatively uniform 3He/4He ratios between 18 and 22 Ra, which is higher than 3He/4He of subaerial Honomanu tholeiites. 20Ne/22Ne and 21Ne/22Ne ratios define linearly correlated trend that overlaps with the Loihi-Kilauea trend. He-Ne systematics of the Hana Ridge indicate that the magmas comprising most parts of the ridge were derived from a source with a primordial less-degassed mantle component. Since Hana Ridge lavas predate the subaerial Honomanu lavas, temporal decrease of 3He/4He ratios suggests that contribution of this primordial component had decreased in the magma source during establishment of Hana Ridge and Haleakala volcano. Pb-Sr isotopes demonstrate that Hana Ridge magmas are representative of the Kea component. However, such isotopic signatures associated with elevated high 3He/4He ratios precludes that the Kea component is a distinct endmember, such as recycled oceanic crust or lithospheric mantle. Alternatively, we propose that it is a common sub-component that is a mixture of Loihi endmember and recycled oceanic crust. Ne isotope ratios of the Hawaiian samples, including the Hana Ridge, show primordial signature irrespective of 3He/4He ratios. Such apparent decoupling of He and Ne isotopes may be also attributed to mixing of the Loihi component and recycled component in the mantle plume, either of which components needs to be elementally fractionated prior to mixing.
KW - Ar/Ar dating
KW - Hawaii
KW - Mantle plume
KW - Noble gas
KW - Submarine ridge
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U2 - 10.1016/j.chemgeo.2006.09.008
DO - 10.1016/j.chemgeo.2006.09.008
M3 - Article
AN - SCOPUS:33847156928
VL - 238
SP - 1
EP - 18
JO - Chemical Geology
JF - Chemical Geology
SN - 0009-2541
IS - 1-2
ER -