Microfacies Data: Matrix and Grains - Microfacies of Carbonate Rocks - page 133

Location 1 2 3 4 5 6 7 8

Depositional Wackestone Wackestone Wackestone Grainstone Packstone Wackestone Floatstone Grainstone

texture Packstone Packstone Packstone Rudstone Rudstone Floatstone Packstone

Bindstone Floatstone Floatstone Wackestone

Associated Peloids Bioclasts Bioclasts Cortoids Bioclasts Bioclasts Bioclasts Peloids

grains Cortoids Peloids Bioclasts Lithoclasts

Stromatolites Intraclasts

Birdseyes

Associated Foraminifera Mollusks Foraminifera Foraminifera Reef biota Mollusks Ammonites Planktonic

fossils Algae Foraminifera Reef biota Calcar. algae Echinoderms foraminifera

Algae Mollusks

Type Simple Simple Simple Simple Simple Simple Simple Simple

of oncoid Multiple Multiple

Prevailing 10 50 mm < 2 mm 2 >10 mm 2 10 mm 2 20 mm 10 20 mm 30 300 mm 1 2 mm

size 5 60 mm

Growth type Concentric Lobate Concentric Concentric Concentric Elliptical Concentric Concentric

Lobate Concentric Radial Inverse Radial

Radial Lobate Inverse

Basic types of M Por > Sp Por > Sp Sp Por M Sp M

oncoids Por > Sp M Comp M Comp M

Comp Comp

Foraminifera

Cortex:
Laminated L L L L L L L

Nonlaminated NL NL NL NL NL

Lamination 1, 2, 5 1, 2, 3 1, 2, 4, 5 1, 3, 4, 5 4, 3 1, 3 1

type
Biotic Calcimicrobes Calcimicrobes Calcimicrobes Calcimicrobes Calcimicrobes Calcimicrobes Microbes Microbes

composition Algae Serpulids Highly diverse Lowdiverse Serpulids

Foraminifera metazoans metazoans Mollusks

Borings + + + -- -- + -- --

Nucleus Lithoclasts Bivalves Corals Corals Corals Cephalopods Cephalopods Peloids

Algae Corals Sponges Mollusks Echinoderms Echinoderms Lithoclasts

Echinoderms Mollusks Algae Mollusks

Echinoderms

Remarks Mixed types -- -- -- -- Glauconite Ferruginous Ferruginous

Eroded and coatings + glauconite

broken coatings

oncoids

Fig. 4.17. Depositional environments and characteristics of Late Jurassic (Oxfordian-Kimmeridgian) oncoids. The criteria
are ordered according to their frequency in about 15 case studies. Although there are many deviations from this scheme,
differences between shallow- and deeper-water oncoids are evident. Associated fossils, shapes and growth types, the lamina-
tion patterns and the type of the bioclasts forming the nuclei are of particular interest. Oncoid sizes reflect changing environ-
mental conditions rather than specific depositional sites. Information on oncoids is provided by studies of the Late Jurassic
'Hauptmumienbank', which can be followed in northern Switzerland and France for at least 100 km. These studies indicate
paleowater depths of a few meters for lagoonal oncoids, about 50 m for oncoids formed on the upper slope, and > 100 m for
basinal oncoids. Based mainly on Dahanayake (1983), Fezer (1988), Gasche (1956), Gasiewicz (1983), Gygi and Persoz
(1987), Gygi (1992), Kutek and Radwanski (1965), Leinfelder and Schmid (2000), Massari (1983), Pümpin (1965), Scherze
(2001) and Schmid (1996).
Comp = composite oncoid, M = micritic oncoid, Por = porostromate oncoid, Sp = Spongiostromate oncoid.