Lacustrine and palustrine carbonate petrography : an overview

Details

Serval ID
serval:BIB_2A88555B16C5
Type
Article: article from journal or magazin.
Collection
Publications
Title
Lacustrine and palustrine carbonate petrography : an overview
Journal
Journal of Paleolimnology
Author(s)
Freytet P., Verrecchia E.P.
ISSN
0921-2728
Publication state
Published
Issued date
2002
Peer-reviewed
Oui
Volume
27
Pages
221-237
Language
english
Abstract
Lacustrine limestones were formerly identified by their faunistic (limnea, planorbis) and floristic (Charophytes) content. For 30 years, indications of pedogenesis have been found in many lacustrine deposits, and consequently the concept of palustrine limestone was defined. Lacustrine fabrics are not that numerous: Varved, laminated, homogeneous, peloidal, brecciated, gravelly, bioturbated (burrows), bioclastic, algal, and stromatolitic. Detrital beds are sometimes present and are interpreted as bottomset deposits. Palustrine fabrics result from exposure and pedogenesis of lacustrine mud. The main processes involved in this evolution are: Cracking, with planar, curved, craze and skew planes, colonization by plants resulting in root traces, marmorization (redistribution of iron due to water table fluctuation), and redistribution of carbonates (needles, subspherical or cylindrical vertical nodules, carbonate coatings, early and late diagenetic crystals, Microcodium). Carbonate palustrine features can be associated with other minerals: Palygorskite, gypsum, or silica. Alternation of lacustrine sedimentation and exposure/pedogenesis leads to the pseudo-microkarst facies resulting from enlargement of the complex network of root traces and horizontal cracks. The voids in the pseudomicrokarst facies are infilled with a polyphased internal sediment composed of carbonate and vadose silt and phreatic and vadose cements. Traces of exposure and pedogenesis are less in evidence in lacustrine bioclastic sands and algal-stromatolitic limestones. Finally, under certain conditions, the surficial laminar horizon and its associated perlitic crust (ooids) develops on palustrine muds and form a desert stromatolite.
Keywords
Calcretes, Nonmarine carbonates, Paleolakes, Pedogenesis, Petrography, Stromatolites
Create date
12/01/2010 13:16
Last modification date
20/08/2019 13:10
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