Geology Reference
In-Depth Information
Basics: Paleokarst
Bosak, P., Ford, D.C., Horacek, I., Glazek, J. (eds., 1989):
Paleokarst - a systematic and regional review. - Devel-
opments in Earth Surface Processes,
1
, 726 pp., (Artia)
Choquette, P.W., James, N.P. (eds., 1988): Paleokarst. -
416 pp., New York (Springer)
Choquette, P.W., James, N.P. (1988): Introduction. - In:
Choquette, P.W., James, N.P. (eds.): Paleokarst. - 1-21,
New York (Springer)
Ford, D.C. (1988): Characteristics of dissolutional cave sys-
tems in carbonate rocks. - In: Choquette, P.W., James,
N.P. (eds.): Paleokarst. - 25-57, New York (Springer)
Ford, D.C. (1995): Paleokarst as a target for modern karst-
ification. - Carbonates and Evaporites,
10
, 138-147
Ford, D.C., Williams, P.W. (1989): Karst geomorphology and
hydrology. - 601 pp., London (Unwin)
Playford, P. (2002): Palaeokarst, pseudokarst, and sequence
stratigraphy in Devonian reef complexes of the Canning
Basin, Western Australia. - In: Keep, M., Moss, S.J. (eds.):
The sedimentary basins of western Australia,
3
. - Pro-
ceedings of the Petroleum Exploration Society of Austra-
lia Symposium, Perth, 763-793
Reinhold, C. (1998): Ancient helictites and the formation of
vadose crystal silt in Upper Jurassic carbonates (southern
Germany). - Journal of Sedimentary Research,
68
, 378-390
Schönlaub, H.P., Klein, P., Magaritz, M., Rantitsch, G.,
Scharbert, S. (1991): Lower Carboniferous paleokarst in
the Carnic Alps (Austria, Italy). - Facies,
25
, 91-118
Smart, P.L., Whitaker, F.F. (1991): Karst processes, hydrol-
ogy, and porosity evolution. - In: Wright, V.P. (ed.): Palaeo-
karsts, and palaeokarstic reservoirs. - Postgraduate Re-
search Institute of Sedimentology, Occasional Publication
Series,
2
, 1-55
Wright, V.P. (1991): Palaeokarst. Types, recognition, controls
and associations. - In: Wright, V.P. (ed.): Palaeokarsts,
and palaeokarstic reservoirs. - Postgraduate Research In-
stitute of Sedimentology, Occasional Publication Series,
2
, 56-88
Further reading:
K031. An 'Atlas of Speleothem Micro-
fabrics' by L. Bruce Railsback, including a glossary of rel-
evant terms and a bibliography, can be found in the Internet
(www.gly.uga.edu/railsback/speleoatlas).
cements beneath unconformities seem to be of mete-
oric-phreatic or deeper-burial origin. Shallow phreatic
cements are clear, iron-poor, blocky or sparry calcite
(Pl. 129/4, 5), commonly non-luminescent with thin
zones of bright luminescence. Burial cements are iron-
rich and commonly inclusion-rich blocky calcite with
dull, variably zoned cathodoluminescence.
• Calcretes and silcretes:
Many paleokarst surfaces
are overlain by calcretes. Siliceous breccias and layers
of white weathered cherts on top of surface karst have
been interpreted as silcretes (Mustard and Donaldson
1990; Schönlaub et al. 1991). Diagnostic criteria of
significant dissolution and successive pervasive silica
cementation are (a) abundant micropores, (b) needle
fiber fabrics, (c) a network of anastomosing walls, and
(d) composite void fillings by euhedrally terminated
megaquartz, radiating chalcedony and coarse mosaic
quartz in the center of voids.
15.2.2 Significance of Paleokarst and Cave
Carbonates
Karstification may affect various types of carbon-
ate buildups, including carbonate platforms, reefs, car-
bonate ramps and pelagic swells. Paleokarst structures
assist in
• recognizing unconformities, subaerial exposure and
stratigraphic breaks (Mussman et al. 1988; Vanstone
1998; Haas 1999; Turgeon and Lundberg 2001),
• correlating stratigraphic units (Charcosset et al.
2000),
• evaluating sea-level fluctuations (Satterley et al.
1994; Calner 2002; compare the case study, Pl. 129),
• identifying paleoclimates. Paleokarst, used in con-
junction with other subaerial exposure features (spe-
cifically paleosols of humid and semiarid phases) to
be distinguished can be critically compared with mod-
ern karst phenonema, to provide an excellent indicator
of paleoclimatic conditions (Jimenez de Cisneros et al.
1993; Wright 1980, 1982, 1988; Burns et al. 1998).
However, because of the complex history of subaerial
weathering processes, paleo-data regarded as indica-
tors should be analyzed within a detailed microstratig-
raphic setting. High-resolution of paleoclimatic varia-
tions are possible by comparing annual variation pat-
terns in speleothems (Railsback et al. 1994; Shopov et
al. 1994; Genty and Quinif 1996).
• understanding hydrological conduits (Klimchouk et
al. 2000). Paleokarst features describe the long-range
effect of descending and ascending waters.
• exploring hydrocarbon reservoir rocks and mineral
deposits (see Chap. 17).
15.3 Travertine, Calcareous Tufa and
Calcareous Sinter
Travertine and calcareous tufa are freshwater carbon-
ates.
The criteria and origin of travertines (layered car-
bonates deposited from mineralized waters at thermal
springs) and tufas (porous carbonates deposited from
cool running waters at springs, in creeks, in zones of
ascending groundwater) were discussed in Sect. 2.4.1.6.
Calcareous sinter is characterized by well developed
lamination and a lack of porosity.
These freshwater carbonates were already known
in the Precambrian, but the number of Phanerozoic
records is low, except for the Quaternary and Tertiary.
Techniques used to study travertines and tufa include
