Siliceous sublacustrine spring deposits around hydrothermal vents in Lake Taupo, New Zealand

Brian Jones*, C. E.J. De Ronde, R. W. Renaut, R Bernhart OWEN

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

Chimneys around hydrothermal vents at a depth of c. 140 m in the Horomatangi Reefs area in Lake Taupo, New Zealand, are composed of amorphous silica (opal-A) with lesser amounts of Mn-, Fe-, and Hg-rich precipitates. Detrital quartz and feldspar grains are found in the surrounding sediments. The associated biota includes fish, bacteria, sponges, crayfish, amphipods, copepods, ostracodes, annelids, and other unidentified organisms. Much of this biota, however, is not preserved in the opal-A deposits. Instead, the silicified biota includes filamentous microbes and diatoms, scattered coccoid microbes, fungal hyphae and spores, rare sponge spicules, and rare worm(?) tubes. The diatoms, coccoid microbes, and fungi were brought into the area with the detrital sediment. In ancient successions, distinction between sublacustrine, terrestrial, and some marine hot spring deposits may be difficult because the precipitates share many similarities. Distinction based on the biota is viable only if palaeoecological information can be inferred from accurately identified organisms. Unfortunately, silicification commonly disguises microbes and precludes their accurate identification. Diagenetic transformation of opal-A to its more stable polymorphs also destroys many original depositional fabrics and silicified microbes. Distinction between the different types of spring deposit may therefore depend on the interpretation of their overall sedimentological and stratigraphic setting.

Original languageEnglish
Pages (from-to)227-242
Number of pages16
JournalJournal of the Geological Society
Volume164
Issue number1
DOIs
Publication statusPublished - Jan 2007

Scopus Subject Areas

  • Geology

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