sedimentary rocks a virtual practical i.g.kenyon

Sedimentary Rocks

A Virtual Practical

I.G.Kenyon

The following slides are all sedimentary rocks

From the information displayed

Decide if the rock is: clastic, organic or chemical

Identify each rock as accurately as possible

Suggest a sedimentary environment in which it may have formed

Identify this Sedimentary Rock 1

1cmPoorly Sorted

40% Muddy Matrix

Rock Fragments

Mineral Grains


2cm

Reacts with dilute hydrochloric acid

Comprises over 70% broken bivalve shells

Remainder of rock is silt and iron oxides


2cm

Comprises entirely clay minerals and carbonaceous material

Well preserved graptolites are found in the rock

Splits into thin layers easily (Fissile)


1cm


Comprises entirely of spherical grains 0.5–1.0mm in diameter


1cmMade up entirely of clay minerals such as kaolinite, illite and bentonite

Homogenous or massive with no

trace of bedding or laminations


4cm

Comprises angular fragments 0.5mm – 8cm in diameter

All parts of the rock react with dilute hydrochloric acid


Comprises mainly sub angular quartz and feldspar grains

20% of the rock has fragments 2 - 4mm in diameter

5mm


1cm

Fibrous appearance

Very low density

Clearly visible remains of organic matter

Rich in carbon


2cm

Composed entirely of silica

Broken surfaces show conchoidal fracture


Comprises some clay minerals such as kaolinite and illite

Has a gritty feel when rubbed on the teeth, >10% quartz present

1cm


Well rounded flint pebbles 8mm – 6cm in diameter

Cement does not react with dilute hydrochloric acid


Rich in carbon, makes a black mark on paper

No recognisable traces of organic material evident


Comprises almost entirely clay minerals, chiefly kaolinite

No bedding or laminations evident. Plastic when wet

1cm

Grain size <1/256mm


Comprises well rounded quartz grains 0.25 – 0.5mm in diameter

Weak iron oxide cement-crumbles in the fingers (friable)

1cm



Rock is made up of coccoliths

Fossil replaced by flint2cm



Made up mainly of broken crinoid stems

1cm


Comprises entirely well rounded quartz grains 0.25–0.75mm in diameter

Very well cemented together by silica

1cm


Does not react with dilute hydrochloric acid

Has a distinct banded appearance

1cm


1cm

Comprises angular to sub angular grains of quartz and feldspar

Contains more than 25% feldspar

Iron oxide cement


1cmParticle size varies

from 1mm – 4cm

Comprises fragments of limestone, basalt,

slate and quartz

All particles are angular

Red iron oxide cement


1cm

Comprises quartz and muscovite grains

Splits readily into slabs 3-6cm thick


Reacts with dilute hydrochloic acid

Made up entirely of angular shell fragments 0.5-3mm

1cm


Has a woody ‘ring’ to it when tapped

Rich in carbon

Low density

Organic structure clearly visible

1cm


Made up entirely of hydrated calcium sulphate

This variety is called Desert Rose

2cm


Contains some clay minerals, chiefly kaolinite

Over 10% quartz present plus mica flakes

Feels gritty when rubbed on the teeth

Mica flakes concentrated on

lamination surfaces

1cm


Jet black colour

Contains over 95% carbon

Vitreous lustre

Marks paper

No recognisable traces of any

organic matter1cm


Made up entirely of clay minerals, chiefly kaolinite

No obvious laminations or bedding present

Contains well preserved trilobite pygydium

2cm


2cm


Has an internal concentric banded structure

Specimen obtained from the roof of a limestone cave

2cm


All parts of the rock react with dilute hydrochloric acid

Contains spherical grains of calcium carbonate over 2mm in diameter

5mmSpherical grains with internal

concentric structure


Composed entirely of sodium chloride

Occurs in thin, near horizontal beds

Often grey, white colourless, orange or

brown

Tastes salty

1cm


Composed entirely of silica

Breaks with a flat or even fracture

Specimen above has been fashioned into a cutting tool

1cm


Comprised of clay minerals and carbonaceous material

Lacks distinct laminations

Contains well preserved plant fragment

1cm


Comprises mainly quartz grains <0.25 in diameter

Brown colour due to 10-15% clay content

Contains external moulds and casts of brachiopods

1cm


1cmContains a high

percentage of sub-rounded to rounded

quartz grains

Some rock fragments

Poorly sorted, particle size ranges from <0.5mm – 1cm

Finer matrix makes up 15-20% of the rock

No reaction with dilute hydrochloric acid


Rich in iron, hence brownish colour (limonite)

Cannot be found forming anywhere on earth today

1cm

Name this Sedimentary Rock 36

Reacts with dilute hydrochloric acid Contains corals preserved

in life position


Reacts with dilute hydrochloric acid Made up of coccoliths

1cm


1cm

Particle size 1mm up to 8mm, quite poorly sorted

Mineralogy mainly sub-angular to sub-rounded quartz and feldspar


Reacts with dilute hydrochloric acid May contain a small

percentage of clay minerals

1cm


1cm

Comprises quartz grains 0.25 – 0.75mm in diameter

Moderately well cemented by glauconite, a pale green mineral

Answers 1.

1. Greywacke 11. Conglomerate

2. Bioclastic Limestone 12. Bituminous Coal

3. Black Shale 13. Clay

4. Oolitic Limestone 14. Desert Sandstone

5. Mudstone 15. Chalk

6. Limestone Breccia 16. Crinoidal Limestone

7. Millstone Grit 17. Orthoquartzite

8. Peat 18. Chalcedony

9. Flint 19. Arkose

10. Siltstone 20. Breccia

Answers 2.

21. Micaceous Sandstone 31. Chert

22. Calcareous sandstone 32. Mudstone

23. Lignite(Brown Coal) 33. Fine Sandstone

24. Rock Gypsum 34. Conglomerate

25. Micaceous Siltstone 35. Ironstone

26. Anthracite 36. Coral Limestone

27. Mudstone 37. (Red) Chalk

28. Tufa 38. Grit

29. Pisolitic Limestone 39. Micrite/Marl

30. Rock Salt 40. Orthoquartzite

The End

sedimentary rocks a virtual practical i.g.kenyon

Documents

rock splits

diameter slide

sedimentary rocks

dilute hydrochloric

carbon slide

sedimentary environment

kenyon slide

fissile slide