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Fig. 4. Samples from the Swiss Jura Mountains site. (a) SEM photograph showing a tubular-like structure resembling
an organic filament (e.g. a fungal hypha) and composed by nanofibres (cotton-ball-like NFC associated with decaying
organic matter). (b-d) Sample from coatings on a cryoclast associated with decaying fungal strands. (b) SEM
photograph showing a network of intertwined nanofibres oriented in two main directions (white rectangle). White star
indicates a NFC crystal. (c) TEM photomicrograph showing a section of a circular structure interpreted as a possible
organic filament (e.g. a fungal hypha) and composed by nanofibres. (d) TEM photomicrograph showing a network of
intertwined nanofibres oriented in two main directions. Also note the presence of a circular section similar to the one
shown in Figure 2c (stars).
contain organic material (Fig. 6a, b) and organized
meshes do contain organic matter (Fig. 6c, d).
organic filaments, that is, nanofibres 'cannot be
fully attributed to direct organic activity' (Jones &
Ng 1988); 'nanofibres show microstructures that
are typical of inorganic, crystalline material'
(Borsato et al. 2000)]. Therefore, the origin of
terrestrial accumulations of nanofibres remains
controversial.
The nanofibres discussed in this paper are similar
to those described in Phillips & Self (1987), based
on their size and flexibility. It is important to note
that they identified the organic filaments associated
with nanofibres as fungi, and the same conclusion is
drawn in this study, based on their size and mor-
phology, as well as presence of macrostructures
Discussion
The presence of nanofibres in various vadose
environments has been widely observed. Their
origin is either attributed to a biogenic factor
('probably rod-shaped calcified bacteria' Phillips
& Self 1987; Ould Mohamed & Bruand 1994;
'microrod attributed to bacteria or nuclei in gel'
Verrecchia & Verrecchia 1994; Loisy et al. 1999)
or physicochemical processes ['precipitation from
pore filling fluids', sometimes assoicated with
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