Carbonate Depositional Environments - Microfacies of Carbonate Rocks - page 10

Rao, C.P. (1996): Modern carbonates. Tropical, temperate,
polar. - 206 pp., Howrah (Carbonates)
Reading, H.E. (1996): Sedimentary environments, processes,
stratigraphy. Third edition. - 688 pp., Oxford (Blackwell)
Scholle, P.A., Bebout, D.G., Moore, C.H. (eds., 1983): Car-
bonate depositional environments. - Amer. Ass. Petrol.
Geol. Mem., 33 , 708 pp.
Scoffin, T.P. (1987): An introduction to carbonate sediments
and rocks. - 274 pp., Glasgow (Blackie)
Tucker, M.E., Wright, V.P. (1990): Carbonate sedimentology.
- 482 pp., Oxford (Blackwell)
Varney, M. (1996): The marine carbonate system. - In:
Summerhayes, C.P., Thorpe, S.A. (eds.): Oceanography.
An illustrated guide. - 182-194, New York (Wiley)
Walker, R.G., James N.P. (eds., 1992): Facies models. Re-
sponse to sea level change. - 409 pp., Ottawa (Geol. Ass.
Canada)
Wilson, J.L. (1975): Carbonate facies in geologic history. -
471 pp., Berlin (Springer)

(corresponding to oceanic environments below about
4 000 m), and hadopelagic zone.
-> Note that the boundaries of the benthic and pe-
lagic depth zones are not fixed accurately. These bound-
aries reflect the situation in modern oceans that are not
necessarily equivalent to depth zones visualized for an-
cient oceans.

2.3.2.2 Horizontal Zonations

The lateral distribution of pelagic organisms with re-
spect to their distance from the coast characterizes two
major zones of the ocean: The neritic zone is the water
that overlies the continental shelf, today generally with
water depth less than 200 m and covering about 8% of
the ocean floor. The term oceanic zone refers to the
water column beyond the shelf break, overlying the
slope and the deep-sea bottoms, generally with water
depths greater than 200 m and down to more than
10 000 m.

2.4 Review of Modern Carbonate
Depositional Environments

The following review is focused on the definitions, main
cr iteria and subdivisions of carbonate settings. The cri-
teria that help recognize these settings and the evalua-
tion of paleoenvironments in ancient carbonate rocks
are discussed in Chap. 12 and 15.

-> Again, keep in mind that these water depths are
not compatible with the situation in many ancient
oceans. Note that the term 'neritic' is often used to de-
scribe sea bottom environments below the neritic wa-
ter column, or shallow-marine environments charac-
terized by significant terrigenous influx.

2.4.1 Non-Marine Carbonate Environments

Basics: Classification of carbonate environments and
obligatory reading
Classification
Edwards, A.R. (1979): Classification of marine paleoenviron-
ments. - Geol. Soc. New Zealand Newsletter, 48 , p. 48
Hedgpeth, J. (1957): Classification of marine environments.
- In: Hedgpeth, J.E. (ed.): The treatise on marine ecology
and paleoecology. Vol.1, Ecology. - Geol. Soc. America
Mem., 67 , 17-28
Kennett, J. (1982): Marine geology. - 813 pp., Englewood
Cliffs (Prentice Hall)
Nybakken, J.W. (1993): Marine biology. An ecological ap-
proach. Third edition. - 462 pp., New York (Harper
Collins)
Summerhayes, C.P., Thorpe, S.A. (eds., 1996): Oceanogra-
phy. An illustrated guide. - 352 pp., New York (Wiley)

Non-marine carbonates originate in terrestrial and
aquatic environments without marine influence. These
carbonates, formed by abiotic and/or biotic processes
differ in many aspects from marine carbonates, which
are much better known to geologists. These carbonates
are formed in terrestrial subaerially exposed settings
and in submerged aquatic settings (Fig. 2.3). The ma-
jor non-marine carbonate environments are listed in
Box 2.2.

Non-marine carbonates formed in terrestrial subaeri-
ally exposed settings comprise pedogenic carbonates,
palustrine carbonates, cave carbonates, eolian carbon-
ates and glacial carbonates.

Obligatory reading
Bathurst, R.G.C. (1994): Carbonate sediments and their di-
agenesis. 2nd enlarged edition - Developments in Sedi-
mentology, 12 , 660 pp., Amsterdam (Elsevier)
Bosellini, A. (1991): Introduzione allo studio delle rocce
carbonatiche. - 317 pp., Ferrara (Italo Bovolenta)
James, N.P., Kendall, A.C. (1992): Introduction to carbonate
and evaporite facies models. - In: Walker, R.G., James
N.P. (eds.): Facies models. Response to sea level change.
- 265-275, Ottawa (Geol. Ass. Canada)
Milliman J.D. (1974): Marine carbonates. - 375 pp., Berlin
(Springer)

2.4.1.1 Pedogenic Carbonates, Paleosols, and
Caliche/Calcretes

Terminology: The term pedogenic refers to soil gen-
esis. Most pedogenic carbonates are formed within soils
rich in calcium carbonate. The term paleosol describes
'a buried soil horizon of the geologic past ' but is often