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Slide # 1

Carbonate Rock Components

Grains (fossils, ooliths, pellets,

intraclasts)

Matrix (carbonate mud)

Cements (chemical precipitate in

pores)

Pores

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Slide # 2

Carbonate Grain Types

Fossils and fossil fragments

Pellets and pelloids

Coated grains: ooliths, pisoliths etc.

Intraclasts

Lithoclasts

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Slide # 3

FOSSILS -

Volumetrically very important

component of carbonate rocks

Provide clues to environment of

deposition

recognized by external shape and by

internal microtextures/structures

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Slide # 4

Living things:

Monera (bacteria)

Protista (algae, forams, radiolarians,

dinoflagellates) Fungi

Plants

Metazoan Animals Invertebrates

Vertebrates

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Slide # 5

CYANOBACTERIA

also known as cyanophytes or as

blue-green algae

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Slide # 6

Cyanobacteria

filamentous, slimy

found in fresh water and shallow marinetoday

long geologic record, from early Precambrian

photosynthetic

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Slide # 7

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Slide # 8AAPG Memoir 27

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Slide # 9

Bathurst, Robin (1975), "Carbonate

Sediments and their Diagenesis" Elsevier

note this alternative interpretation

Gi ll

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Slide # 10

Girvanella

Scholle, P.A. (1978), "A Color Illustrated Guide to Carbonate Rock . . ." AAPG Memoir 27.

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Slide # 11

Filamentous cyanobacterium,

Western Australia,

3.5 billion years old

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Slide # 12

Cyanobacteria are important

because . . . Source of atmospheric oxygen

Micrite envelopes

Algal mats

Stromatolites

Oncoliths Mineralization controls

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Slide # 13

Blue-green photosynthetic

agents reflect blue-green light

and absorb red light.

Red light does not penetrate

far into the water, so the

cyanobacteria are confined

to shallow water.

Conversely, red algae use blue

light and can live in muchdeeper water.

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Slide # 14

J.L. Wray, in Haq and Boersma

(1978), "Introduction to Marine

Micropaleontology" Elsevier

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Slide # 15

Cyanobacteria

form slimy film on most sea-floor objects

combination of borings and adhered surfacedebris creates micrite envelopes

micrite envelopes survive considerable

diagenesis, including recrystallization,dissolution, preserving grain outlines,permitting petrographic analysis.

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Slide # 16

B th t R bi (1975) "C b t

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Slide # 17

Bathurst, Robin (1975), "Carbonate

Sediments and their Diagenesis" Elsevier

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Slide # 18

"Algal" mat

[= cyanobacterial mat]

sediment binding

flexible and tough

crinkly surface

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Slide # 19

Milliman (1974)

"Marine Carbonates"

Springer-Verlag.

Figure 20.

l l t B ffi B T

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Slide # 20

algal mat, Baffin Bay, Texas

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Slide # 21

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Slide # 22

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Slide # 23

crinkly lamination (algal mat) Jurassic England

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Slide # 24

crinkly lamination (algal mat) Jurassic, England.

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Slide # 25

Stromatolites

mound-shaped buildups created

by cyanobacteria

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Slide # 26

Wray J L (1977) "Calcareous Algae" Elsevier

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Slide # 27

Wray, J.L. (1977), Calcareous Algae Elsevier

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Slide # 28

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Slide # 29

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Slide # 30

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Slide # 31

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Slide # 32

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Slide # 33Toomey, D.F., and J. A. Babcock, (1983), Colorado School of Mines Professional Contributions #11.Conophyton-type stromatolites, Precambrian, Allamoore Formation, West Texas

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Slide # 35

Shark Bay

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Slide # 36

Hamelin Pool

Modern stromatolites, Shark Bay, Australia

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Slide # 37

Modern stromatolites, Shark Bay, Australia

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Slide # 38

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Slide # 39

Stromatolite reefs

Cyanobacteria are capable of forming

"reefs" particularly in the Precambrian

and Early Paleozoic

Examples from the Athapuscow

Aulacogen of Arctic Canada

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Slide # 40AAPG Memoir 33, page 377

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Slide # 41AAPG Memoir 33, page 382

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Slide # 42

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Slide # 43

Oncoliths

spherical, encrusting algal balls

around shells or other nuclei

oncoliths

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Slide # 44

oncoliths

Flagstaff Formation, Utah.

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