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

Steffen Trümper,Ronny Rößler,Jens Götze

doi:10.3390/min8100432

Steffen Trümper, Ronny Rößler + Show 1 more

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https://doi.org/10.3390/min8100432

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Abstract

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).

Highlights

Both permineralized and petrified plants with preserved cellular details are among the most fascinating remains of the flora and their evolution during Earth history [1,2,3,4]
The latter is caused by a green mineral phase occupying the former cell walls or partially filling the cell lumina (Figure 4e)
Since 2000, several studies have demonstrated the vital contribution of CL microscopy in type of embedding host rock (Figure 14)

Summary

Introduction

Both permineralized and petrified plants with preserved cellular details are among the most fascinating remains of the flora and their evolution during Earth history [1,2,3,4]. Corresponding fossil occurrences are distributed worldwide in sedimentary and volcanic rocks encompassing million year timespans, beginning with the colonization of the terrestrial realm by higher plants in the Devonian [5]. Volcanically-affected landscapes [7], which might be expected to be more prone to rapidly preserve plant remains, are commonly represented in the fossil record. In epiclastic sedimentary environments petrifactions frequently occur, even in quite unexpected cases, such as low latitude tropical rainforests, which usually show the largest recycling rates of any organic matter [8]. Most permineralized or petrified wood is silicified, viz. preserved by

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