Factors controlling growth of modern tufa: results of a field experiment - Tufas and Speleothems: Unravelling the Microbial and Physical Controls - page 182

Folk (1994) from La Zitelle spring fall approxi-
mately within the same range. Slightly lower
values, varying from 2.8 - 56.5 cm a 21 , were
reported by Bargar (1978, 13) from Mammoth Hot
Springs. Guo & Riding (1992) measured thickness
of laminae in Terma San Giovanni and accepted
daily character of lamination. Since a lamina is
0.5 mm thick one can calculate the thickness of
annual increment to c. 18 cm. The measurements
carried out during the present experiment are
based predominantly on mass increment, which
impedes direct comparisons. However, the
maximum thickness of tufa formed within 14
months at the L ´ ˇ ky site is 24 mm. It is lower than
the above quoted values for travertines. The tufa
growth rate at the L ´ ˇ ky site is therefore
intermediate between the values typical of tufas
and travertines. This may be explained by the
origin of water feeding the studied tufa at L ´ ˇ ky.
The stream water is a mixture of shallow and deep
circulating components. Consequently, the water
feeding the tufa abounds in TDS, including bicar-
bonate ions and dissolved CO 2 , which results in
relatively high SI calc. values, reaching 1.27
(Table 3). Chemical composition of water is thus
responsible for the unexpectedly high rate of tufa
growth at L ´ ˇ ky.
Slightly lower is the rate of growth of the Hunag-
long travertine complex in China, which also is fed
by a mixture of waters from deep and shallow circu-
lation. The mean growth rate of travertine in a fast-
flow setting equals there 0.9252 mg/cm 2 /day
according to recalculated data by Liu et al. (1995).
Lu et al. (2000) gave slightly higher values for tra-
vertine growth rate in a fast-flow setting in Hunag-
long, which ranged from 0.75 to 5.4 mg/cm 2 /day.
Another travertine depositing system fed by a
mixture of different waters has been described by
Liu et al. (2006) from Yunnan province in China.
The travertine growth varies there between 6.5 and
10.2 mm a 21 .
Regardless of the origin of water, the tufa
recently precipitated at the L´ ˇ ky site is similar in
texture to tufas fed exclusively by water from
shallow karst aquifers. The same is true for the
Pleistocene tufa at L´ ˇ ky (Gradzi ´ ski et al. 2008).
Fig. 27. Relationship between mean annual growth rate
of tufa and mean annual air temperature as well as
selected physicochemical parameters of feeding water;
mean annual growth rate for Karw ´ w, L ´ ˇ ky and H ´ j
sites is calculated as mean increment on yearly or longer
than seasonally exposed limestone tablets (see Table 3);
data on Huanglong and Tartare sites, from Liu et al.
(1995) and Bono et al. (2001) respectively, are multiply
by 4 to unify the methods of calculation with the
present data