| Abstract: | From 1994 through 1998, the eruption of Ki??lauea, in Hawai‘i, was dominated by steady-state effusion at Pu‘u ‘O??‘??o that was briefly disrupted by an eruption 4 km uprift at Np??au Crater on January 30, 1997. In this paper, I describe the systematic relations of whole-rock, glass, olivine, and olivine-inclusion compositions of lava samples collected throughout this interval. This suite comprises vent samples and tube-contained flows collected at variable distances from the vent. The glass composition of tube lava varies systematically with distance and allows for the "vent-correction" of glass thermometry and olivine-liquid KD as a function of tube-transport distance. Combined olivine-liquid data for vent samples and "vent-corrected" lava-tube samples are used to document pre-eruptive magmatic conditions. KD values determined for matrix glasses and forsterite cores define three types of olivine phenocrysts: type A (in equilibrium with host glass), type B (Mg-rich relative to host glass) and type C (Mg-poor relative to host glass). All three types of olivine have a cognate association with melts that are present within the shallow magmatic plumbing system during this interval. During steady-state eruptive activity, the compositions of whole-rock, glass and most olivine phenocrysts (type A) all vary sympathetically over time and as influenced by changes of magmatic pressure within the summit-rift-zone plumbing system. Type-A olivine is interpreted as having grown during passage from the summit magmachamber along the east-rift-zone conduit. Type-B olivine (high Fo) is consistent with equilibrium crystallization from bulk-rock compositions and is likely to have grown within the summit magma-chamber. Lower-temperature, fractionated lava was erupted during non-steady state activity of the Na??pau Crater eruption. Type-A and type-B olivine-liquid relations indicate that this lava is a mixture of rift-stored and summit-derived magmas. Post-Na??pau lava (at Pu‘u ‘O?? ‘o) gradually increases in temperature and MgO content, and contains type-C olivine with complex zoning, indicating magma hybridization associated with the flushing of rift-stored components through the eruption conduit. |
| Genre: | Article |
| ProdID: | 70023640 |
| Citation Author: | Thornber, C. R. |
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| Citation End Page: | 266 |
| Citation Issue: | 2 |
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| Citation Language: | English |
| Citation Larger Work Title: | Canadian Mineralogist |
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| Citation Number Of Pages: | 28 |
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| Citation Search Results Text: | Olivine-liquid relations of lava erupted by Kilauea volcano from 1994 to 1998: Implications for shallow magmatic processes associated with the ongoing east-rift-zone eruption; 2001; Article; Journal; Canadian Mineralogist; Thornber, C. R. |
| Citation Start Page: | 239 |
| Citation Volume: | 39 |
| Citation Year: | 2001 |
| Type: | citation/reference |
| Text: | Olivine-liquid relations of lava erupted by Kilauea volcano from 1994 to 1998: Implications for shallow magmatic processes associated with the ongoing east-rift-zone eruption; 2001; Article; Journal; Canadian Mineralogist; Thornber, C. R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Mon, 1 Jan 2001 00:00 -0600 |
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