Geology Reference
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Fig. 6. (a) Limestone and copper tablets (small arrows)
at the L´ ˇky top point completely covered with tufa after
120 days of exposition, March 2003; (b) tablets at the
Z´zriv´ site, left hand pair after 122 days of exposition,
right-hand pair after 429 days of exposition, the much
more encrustation of the limestone tablet than paired
copper one is visible; the tablets are dry owing to
low-flow condition, October 2003; big arrows indicate
direction of water flow.
Fig. 7. Growth rate of tufa on tablets exposed at Karw´w
and Z´zriv´ sites.
tufa-depositing streams in Europe (e.g. Golubi´
1967; Penetcost & Spiro 1990; Merz-Preiß &
Riding 1999; Arp et al. 2001; Pentecost 2003,
2005). Several species of Phormidium inhabit the
studied sites (T. Mrozi´ska, pers. comm., 2003).
Thus, the filaments forming radiate fans probably
represent this genus. However, other filaments of
similar size may be related to any filamentous
cyanobacteria.
The third type of filaments comprises short
forms up to 40 mm in length. Diameter of individual
filament varies and maximally reaches 7 mm
(Figs 12c & 13a - b). Filaments of this type are pre-
served as irregularly curved moulds. Their dimen-
sions and co-occurrence with diatom frustules
suggest that they represent diatom stalks (cf. Wins-
borough & Golubi´ 1987; Freytet & Verrecchia
1998). Under SEM they are visible as pits in faces
of sparrry crystals (Fig. 13c - d; cf. Pedley 2000).
however, they do not seem to serve as nucleation
surfaces (Fig. 12a). The filament moulds form paral-
lel or upward radiating elongated inclusions, which
in some cases are arranged in horizons within sparry
crystals (Fig. 12b, c). Analogous preservation of
filamentous algae in modern tufa was reported
from Oklahoma by Love & Chafetz (1988) and
from the British Islands by Pedley (1994, fig. 20).
Filaments belonging to this type are variously
oriented. They may form fans composed of several
upward radiating filaments (Fig. 12d - f ). The fila-
ments do not seem to exhibit branching, however
the number of filaments in the fan top appears to
be larger than at the base.
Biological affinity of this type of filaments is not
clear. Their size implies that they belong to cyano-
bacteria. Upward radiating orientation of filaments
shares an affinity with some species of Phormidium.
Freytet & Verrecchia (1998) depicted and illustrated
Phormidium incrustatum and P. faveolarum which
are characterized by alike radial arrangement of fila-
ments. Both cyanobacteria are noted from many
Desmid Oocardium stratum. Sparitic tubes build-
ing
complicated,
upward
branching
bushes
are
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