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Major Element, Volatile, and Stable Isotope Geochemistry of Hawaiian Submarine Tholeiitic Glasses
| Content Provider | Semantic Scholar |
|---|---|
| Author | Michael García David Kwesi Aggrey |
| Copyright Year | 2007 |
| Abstract | Tholeiitic glasses were dredged from the submarine rift zones of the five volcanoes comprising the island of Hawaii and Loihi Seamount. The major element composition of the glasses follows a systematic trend that is related to the stage of evolution of the volcano. Glasses from Loihi Seamount (the youngest Hawaiian volcano) are enriched in Fe, Ca, Ti, Na, and K and depleted in Si and A1 relative to the glasses from the other, older volcanoes. Kilauea is intermediate in age and its glasses are intermediate in composition between those from Loihi and Mauna Loa, the largest and oldest of the active Hawaiian tholeiitic volcanoes. The volatile contents (H20, GO2, S, F, G1) of the glasses from these volcanoes follow the same trend (highest in Loihi; lowest in Mauna Loa). Glasses from Hualalai Volcano are similar in composition to those from Mauna Loa; those from Kohala Volcano are similar to Kllauea; Mauna Kea glasses range from Mauna Loa-like to Kilauea-like. The observed systematic variation in composition of Hawaiian tholelites may be related to the progressive melting and depletion of the source of these volcanoes during their growth. Oxygen and hydrogen isotope analyses were made on many of the glasses from each volcano. The 6180 values of Hawaiian tholelites are distinctly lower than those of mid-ocean ridge basalt (MORB) (averages: 5.1 versus 5.7). These low values are probably a distinct feature of hot spot lavas. The 6D values for these glasses (-88 to -61) are typical of mantle and MORB values. Thus the H20 in the Hawaiian glasses is probably of magmatic origin. Previous isotopic and trace element data indicate that the source of Hawaiian tholelites contains two distinct source components. Based on the results of this study, the plume component in the source for Hawaiian tholelites is characterized by moderate 87Sr/86Sr (0.7035-0.7037) and 2ø6pb/2ø4pb ratios (18.6-18.7), a low 6180 value (~5.0), and greater contents of volatiles, Fe, Ca, Ti, Na and K relative to the MORB source. 1Also at Department of Chemistry, University of Hawaii, Honolulu. Copyright 1989 by the American Geophysical Union. Paper number 89JB00894. 0148-0227/89/89JB-00894505.00 Introduct ion Trace element, rare gas, and isotopic data indicate that Hawaiian lavas (including shield and posterosional lavas) and other oceanic island basalts (OIB) evolved by mixing melts from several geochemically distinct sources. However, the number and compositions of the mixing end-members and the relationship of these components to specific mantle sources remain points of controversy (see Zindler and Hart [1986] for a review). The source for Hawaiian tholelites apparently consists of two principal components based on Pb, Sr and Nd isotope data [Tatsumoto, 1978; Tatsumoto et al., 1987; West et al., 1987]. One of these components is thought to be from a plume but there is little agreement on the nature of the nonplume component (for example, 100 Ma oceanic lithosphere [Stille et al., 1986]; recycled oceanic lithosphere [Hofmann et al., 1986]). Isotopic end-members can be identified among Hawaiian tholeiites. Kilauea is considered one end-member and Koolau has been considered the other with tholelites from other volcanoes in between. However, new data for Kahoolawe and Lanai tholelites show that Koolau is no longer unique (as suggested by Tatsumoto et al. [1987]) and that the range of Hawaiian tholelites must be extended [West et al., 1987]. In order to complement previous studies and more fully evaluate the nature of compositional variation among Hawaiian tholelites, we undertook a comprehensive geochemical study of submarine glasses from each of the five volcanoes comprising the island of Hawaii (Mauna Kea, Mauna Loa, Kilauea, Kohala and Hualalai) and Loihi Seamount (Figure 1). This is the first such study where the geochemistry of a single suite of Hawaiian lavas is thoroughly documented. Fresh submarine glasses were used to avoid the effects of alteration and crystal accumulation. Such glasses may represent virtually unmodtfied magmatic liquids. Furthermore, submarine erupted glasses may contain preeruption concentrations of volcanic gases [Moore, 1970; Moore and Schilling, 1973] which provide another important parameter in the evaluation of the source of Hawaiian lavas. Finally, since all the glasses analyzed from each of the volcanoes are tholeiitic, we were able to study lavas that are broadly representative of the shield-building stage of development for each of the volcanoes. This would not be possible if only subaerial lavas |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.soest.hawaii.edu/GG/FACULTY/garcia/publications/Garcia_etal_1989_Hawaiian_submarine_glasses.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Complement System Proteins Composition Copyright CpG Islands Depletion region Document completion status - Documented Duvalius lanai Eyeglasses Field electron emission Gases Hawaiian Herbal Medicine Hydrogen International System of Units Ions Iron Isotopes Largest Lead Liquid substance Lithosphere Loa (invertebrate) Loa loa Mantle Megabalanus volcano Numerical aperture Opaepele loihi Oxygen Plume (fluid dynamics) Population Parameter Progressive scan Recycling Shield Device Component Sodium Stable angina Stunt Island Thyrocopa kea Tilapia mossambica Titanium Trace Elements Tree accumulation contents - HtmlLinkType |
| Content Type | Text |
| Resource Type | Article |
