The silicification of trees in volcanic ash - An experimental study

Ballhaus, Chris; Gee, Carole T.; Bockrath, Conny; Greef, Karin; Mansfeldt, Tim; Rhede, Dieter

doi:10.1016/j.gca.2012.01.018

Cited by 60 publications

(31 citation statements)

References 37 publications

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“…The presence of diatom fossils in the lakebed sediment is evidence that dissolved silica was available, and mineralization of the wood with calcium phosphate rather than silica is probable evidence that that Eh/pH conditions within the buried tissue were not favorable for silica precipitation. This is consistent with experimental evidence [78] demonstrating that when obsidian powder is used as a silica source, dissolved Si levels were elevated at pH values > 9. For wood that contained absorbed silica, a decrease in pH caused breakdown of hydrogen bonds between silica complexes and organic molecules, releasing silica back into aqueous solution.…”

Section: Mineralization Processsupporting

confidence: 91%

“…This mode of occurrence is evidence that unique geochemical conditions were present within the buried plant tissue. The hyaloclastic lake sediment would have potentially provided an abundant source of dissolved silica: pumice and volcanic ash are commonly associated with silicified wood, and experimental studies have shown obsidian to be a good source of dissolved silica for wood mineralization [78]. The presence of diatom fossils in the lakebed sediment is evidence that dissolved silica was available, and mineralization of the wood with calcium phosphate rather than silica is probable evidence that that Eh/pH conditions within the buried tissue were not favorable for silica precipitation.…”

Section: Mineralization Processmentioning

confidence: 99%

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The Bruneau Woodpile: A Miocene Phosphatized Fossil Wood Locality in Southwestern Idaho, USA

et al. 2017

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Abstract:The Bruneau Woodpile site has long been popular among fossil collectors; however, the deposit has received scant attention from scientists. Our research reveals that the fossilized wood was deposited ca. 6.85 Ma, within the Chalk Hills Formation, and was mineralized with carbonate-fluorapatite. The diverse assemblage of conifers and hardwoods is representative of the warm temperate forests that flourished in southwest Idaho, USA during the late Miocene. Limb and trunk fragments preserved in a single thin sandstone bed appear to represent woody debris that was transported by streams. One possible explanation is that wood, pumice, and sandy volcaniclastic sediment arrived separately as a result of ordinary stream action, and later were combined into a single assemblage during a subsequent high-energy sedimentation event. We favor an alternate hypothesis: a catastrophic event (e.g., a windstorm) damaged trees on slopes bordering the ancient lake. Branches and small trunk fragments were carried by wind and rain into local streams and ponds where they became waterlogged. After a delay that allowed pumice and wood to become saturated, storm water transported these materials, along with finer volcaniclastic sediment, into a lake. The resulting density current produced a fining-upward sedimentary cycle where wood was preserved in the lowest, coarsest stratum.

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Section: Mineralization Processsupporting

confidence: 91%

Section: Mineralization Processmentioning

confidence: 99%

The Bruneau Woodpile: A Miocene Phosphatized Fossil Wood Locality in Southwestern Idaho, USA

et al. 2017

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“…[2,3] cf. [71,72]). For this reason, wetland plants and aquatic elements of the fauna are by far the most likely to be preserved in geothermal environments.…”

Section: (E) Taphonomic Featuresmentioning

confidence: 99%

A review of active hot-spring analogues of Rhynie: environments, habitats and ecosystems

Channing¹

2017

Phil. Trans. R. Soc. B

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The Lower Devonian Rhynie chert formed as silica sinter entombed an early terrestrial ecosystem. Silica sinter precipitates only from water flowing from alkali-chloride hot springs and geysers, the surface expression of crustal-scale geothermal systems that form low-sulfidation mineral deposits in the shallow subsurface. Active alkali-chloride hot springs at Yellowstone National Park create a suite of geothermally influenced environments; vent pools, sinter aprons, run-off streams, supra-apron terrace pools and geothermal wetlands that are habitats for modern hot-spring ecosystems. The plant-rich chert, which makes Rhynie internationally famous, probably formed in low-temperature environments at the margins of a sinter apron where frequent flooding by geothermal water and less frequent flooding by river waters created ephemeral to permanent wetland conditions. Here, the plants and associated microbes and animals would be immersed in waters with elevated temperature, brackish salinity, high pH and a cocktail of phytotoxic elements which created stresses that the fossil ecosystem must have tolerated. The environment excluded coeval mesophytic plants, creating a low-diversity hot-spring flora. Comparison with Yellowstone suggests the Rhynie plants were preadapted to their environment by life in more common and widespread environments with elevated salinity and pH such as coastal marshes, salt lakes, estuaries and saline seeps.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'.

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“…Fundamental studies and experiments [12][13][14][15], both under natural conditions and in the laboratory, have contributed towards the understanding of quartz precipitation, plant tissue impregnation and the related time frame [2,[16][17][18]. However, many fossil woods and their occurrences cannot be explained though uniformitarian comparisons, such as postvolcanic hotsprings [19,20].…”

Section: Introductionmentioning

confidence: 99%

Deciphering Silicification Pathways of Fossil Forests: Case Studies from the Late Paleozoic of Central Europe

2018

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The occurrence and formation of silicified wood from five late Paleozoic basins in Central Europe was investigated. Fossil wood from diverse geological settings was studied using field observations, taphonomic determinations as well as mineralogical analyses (polarizing microscopy, cathodoluminescence (CL) microscopy and spectroscopy). The results indicate that silicification is either a monophase or multiphase process under varying physico-chemical conditions. In particular, CL studies revealed complex processes of silica accumulation and crystallization. The CL characteristics of quartz phases in silicified wood can mostly be related to blue (390 and 440 nm), yellow (580 nm), and red (650 nm) emission bands, which may appear in different combinations and varying intensity ratios. Yellow CL is typical for initial silicification, reflecting quick precipitation under oxygen-deficient conditions caused by initial decay of the organic material. Blue CL is predominantly of secondary origin, resulting from replacement of precursor phases by a secondary hydrothermal quartz generation or subsequent silicification of wood. The red CL can be related to a lattice defect (non-bridging oxygen hole center—NBOHC).

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The silicification of trees in volcanic ash - An experimental study

Cited by 60 publications

References 37 publications

The Bruneau Woodpile: A Miocene Phosphatized Fossil Wood Locality in Southwestern Idaho, USA

The Bruneau Woodpile: A Miocene Phosphatized Fossil Wood Locality in Southwestern Idaho, USA

A review of active hot-spring analogues of Rhynie: environments, habitats and ecosystems

Deciphering Silicification Pathways of Fossil Forests: Case Studies from the Late Paleozoic of Central Europe

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