Acceleration of sinter diagenesis in an active fumarole, Taupo Volcanic Zone, New Zealand

Show simple item record Lynne, Bridget en Campbell, KA en Perry, RS en Browne, Patrick en Moore, JN en 2012-06-26T03:21:13Z en 2006 en
dc.identifier.citation GEOLOGY 34(9):749-752 01 Sep 2006 en
dc.identifier.issn 0091-7613 en
dc.identifier.uri en
dc.description.abstract Siliceous sinters form where nearly neutral pH, alkali chloride waters discharge at the surface (<100 °C). They may preserve biogenic and abiogenic material and therefore archive paleoenvironmental settings. Freshly precipitated sinters undergo diagenesis through a five-step series of silica mineral phase changes, from opal-A to opal-A/CT to opal-CT to opal-C to quartz. Transformation rates vary among sinters because post-depositional conditions can accelerate or retard diagenesis, meanwhile preserving or destroying biosignals. We monitored alteration and diagenesis of newly precipitated, filamentous microbe-rich sinter during a two-year field experiment, where sinter was suspended inside a fumarole at Orakei Korako, Taupo volcanic zone, New Zealand. Patchy and complex diagenesis resulted from changes in environmental conditions, including variations in temperature, pH, and the intermittent deposition of sulfur. Throughout the experiment, opal-A was dissolved by acidic steam condensate, and reprecipitated locally. Quartz crystals grew on the sinter surface within 21 weeks. Previous reports of transformation rates from opal to quartz are on the order of thousands of years in duration. Thus, our results show that fumarolic overprinting accelerates diagenesis. Microbial preservation was not favourable because primary filamentous fabrics were obscured by deposition of opal-A microspheres, smooth silica infill, and sulfur. If ancient hydrothermal systems were among the likely places where early life flourished, it is necessary to distinguish between depositional features and those inherited during diagenesis. This near–real time experiment enabled observations on environmental controls of diagenetic change in silica minerals and illustrated the variability of conditions that can occur in nature during this complex process. en
dc.publisher Geological Society of America en
dc.relation.ispartofseries Geology en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. Details obtained from en
dc.rights.uri en
dc.title Acceleration of sinter diagenesis in an active fumarole, Taupo Volcanic Zone, New Zealand en
dc.type Journal Article en
dc.identifier.doi 10.1130/G22523.1 en
pubs.issue 9 en
pubs.begin-page 749 en
pubs.volume 34 en
dc.rights.holder Copyright: Geological Society of America en
pubs.end-page 752 en
dc.rights.accessrights en
pubs.subtype Article en
pubs.elements-id 66735 en Engineering en Engineering Science en
pubs.record-created-at-source-date 2010-09-01 en

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