The oxygen isotopes of albite, quartz, and zeolites from the Hokonui Hills, New Zealand, constrai... more The oxygen isotopes of albite, quartz, and zeolites from the Hokonui Hills, New Zealand, constrain crystallization temperatures and the type of pore fluids present during diagenesis. A section of altered vitric tufts in this region contains an extremely sharp reaction boundary between a heulanditechlorite assemblage containing fresh detrital plagiodase and a laumontite-albite-quartz assemblage. A laumontite vein follows the local joint pattern and forms the reaction boundary, suggesting that laumontitization occurred as a result of fracturing and increased fluid flow during uplift. The albite (~80 = + 15.0)-quartz (6~80 = + 19.9 to + 20.5) geothermometer constrains the temperature of alteration between 145 ~ and 170"(2 with a pore water 6isO of + 1.8 to + 3.5. The tuff was buried to an estimated maximum temperature of about 225*(2, indicating that alteration occurred after maximum burial.
The oxygen isotopes of albite, quartz, and zeolites from the Hokonui Hills, New Zealand, constrai... more The oxygen isotopes of albite, quartz, and zeolites from the Hokonui Hills, New Zealand, constrain crystallization temperatures and the type of pore fluids present during diagenesis. A section of altered vitric tufts in this region contains an extremely sharp reaction boundary between a heulanditechlorite assemblage containing fresh detrital plagiodase and a laumontite-albite-quartz assemblage. A laumontite vein follows the local joint pattern and forms the reaction boundary, suggesting that laumontitization occurred as a result of fracturing and increased fluid flow during uplift. The albite (~80 = + 15.0)-quartz (6~80 = + 19.9 to + 20.5) geothermometer constrains the temperature of alteration between 145 ~ and 170"(2 with a pore water 6isO of + 1.8 to + 3.5. The tuff was buried to an estimated maximum temperature of about 225*(2, indicating that alteration occurred after maximum burial.
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