https://repository.kopri.re.kr/handle/201206/5244 2026-04-07T05:39:35Z 2026-04-07T05:39:35Z Hahm, Doshik Erik H. Hauri Paterno R. Castillo Barry B. Hanan James W. Hawkins David R. Hilton https://repository.kopri.re.kr/handle/201206/8452 2022-03-24T07:13:31Z 2011-01-01T00:00:00Z

Title: Volatile systematics of the Lau Basin - resolving the effects of source variation, magmatic degassing and crustal contamination Authors: Hahm, Doshik; Erik H. Hauri; Paterno R. Castillo; Barry B. Hanan; James W. Hawkins; David R. Hilton Abstract: The Lau Basin erupts lavas with a range of geochemical features reflecting a complex history of interaction involving different mantle sources. The Valu Fa Ridge (VFR) and Mangatolu Triple Junction (MTJ) region has lavas with arc-like characteristics, Niuafo' ou Island (NV), Peggy Ridge and Central and Eastern Lau Spreading Centers (PR, CLSC and ELSC) erupt mid-ocean ridge basalt (MORB)-like volcanics, whereas the Rochambeau Bank (RB) has features akin to ocean island basalt (OIB). To characterize the volatile systematics of these various regions, we report a comprehensive study of 39 submarine lavas from these various eruptive centers encompassing analyses of the noble gases (He, Ne, and Ar) and carbon (CO2) – both isotopes and abundances - together with other major volatile phases (H2O, S, Cl, and F). Helium isotope ratios of the NV, MTJ, CLSC, and ELSC are MORB-like for the most part except for differentiated lavas that tend to have lower, more radiogenic 3He/4He values. The RB has considerably higher 3He/4He ratios (up to 23 RA in this work) which extend as far south as the PR. The influence of 'plume-like' sources in the RB is also apparent in Ne isotopes: RB samples follow a trend similar to Hawaiian basalts in 3- isotope neon space. However, RB lavas have lower 40Ar/36Ar (300-730) and higher [36Ar] than CLSC and ELSC, suggesting greater air contamination. Elemental He/Ne

2011-01-01T00:00:00Z Hahm, Doshik Park, Sung Hyun Lee, Yung Mi Hong, Soon Gyu https://repository.kopri.re.kr/handle/201206/8360 2022-03-24T07:13:49Z 2011-01-01T00:00:00Z

Title: Bacterial Diversity Change of the Surface Seawater from Dunedin, New Zealand to Australian-Antarctic Ridge (AAR) Authors: Hahm, Doshik; Park, Sung Hyun; Lee, Yung Mi; Hong, Soon Gyu Abstract: The prokaryotic microbial diversity of surface seawater from the Dunedin, New Zealand to the Australian-Antarctic Ridge (AAR), the largest unexplored expanse of the global mid- ocean ridge system was analyzed by pyrosequencing method.

2011-01-01T00:00:00Z K. Sims Park, Sung Hyun P. Michael N. Abe T. Plank Y. Orihashi https://repository.kopri.re.kr/handle/201206/8056 2022-03-24T07:13:37Z 2010-01-01T00:00:00Z

Title: Geochemical characteristics of off-axis lavas from the Chile Rise Authors: K. Sims; Park, Sung Hyun; P. Michael; N. Abe; T. Plank; Y. Orihashi Abstract: The Chile Rise, a divergent boundary between the Nazca and Antarctic plates, is unique because it is being subducted beneath the South American plate. Even though the ridge is located on the subducting slab, previous studies (e.g. Klein and Karsten, Nature,V374, 1995) of axial lavas have proposed that the easternmost part of ridge (Segment 1) might be contaminated by a young subduction component. The most plausible explanation for this posited subduction component is transport of the subduction components through a "slab window" from the mantle wedge. For this study, off-axis lavas from Segment 1 were obtained on board R/V Mirai, JAMSTEC in 2009. In contrast to axial lavas, which are sediment covered due to the high sedimentation rate of the near shore area, many of the off-axis lava flows were directly exposed on the seafloor, suggesting recent off-axis volcanic activity. These off-axis lavas were analyzed for major and trace element abundances to evaluate both the melting processes involved in this off-axis magmatism and the extent of mantle heterogeneity beneath this ridge-subduction environment. The off-axis lavas are primitive (MgO is 7.5~ 8.4) and similar to N-MORB in their major element compositions. Compared to published on-axis data for the Chile Rise basalts (Klein and Karsten, Nature,V374, 1995), they are slightly higher in TiO2 for a given MgO content, but have similar Na2O. H2O/Ce contents of the lavas are close to the Pacific MORB/OIB maximum (~220), but one sample is higher (>300). These off-axis lavas are also slightly enriched in fluid mobile elements such as K2O, Ba and Pb compared to N-MORB, suggesting their lava source was similarly influenced by subduction components. For example, a diagram of K2O/TiO2 vs. K2O/H2O shows a trend that is oblique to the Pacific MORB trend, but may be going towards a subduction component. Trends towards a subduction component are less pronounced in off-axis lavas than those seen among the axial lavas; none-the-les

2010-01-01T00:00:00Z