Transcript Slide 1

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
1cm
Poorly Sorted
40% Muddy Matrix
Rock Fragments
Mineral Grains
Identify this Sedimentary Rock 2
Reacts with dilute
hydrochloric acid
Comprises over 70%
broken bivalve shells
Remainder of rock is
silt and iron oxides
2cm
Identify this Sedimentary Rock 3
2cm
Comprises entirely clay minerals and carbonaceous material
Well preserved graptolites are found in the rock
Splits into thin layers easily (Fissile)
Identify this Sedimentary Rock 4
1cm
Reacts with dilute hydrochloric acid
Comprises entirely of spherical grains 0.5–1.0mm in diameter
Identify this Sedimentary Rock 5
Made up entirely
of clay minerals
such as kaolinite,
illite and bentonite
Homogenous or
massive with no
trace of bedding
or laminations
1cm
Identify this Sedimentary Rock 6
4cm
Comprises angular fragments 0.5mm – 8cm in diameter
All parts of the rock react with dilute hydrochloric acid
Identify this Sedimentary Rock 7
5mm
Comprises mainly sub angular quartz and feldspar grains
20% of the rock has fragments 2 - 4mm in diameter
Identify this Sedimentary Rock 8
Fibrous appearance
Very low density
Clearly visible remains
of organic matter
Rich in carbon
1cm
Identify this Sedimentary Rock 9
2cm
Composed entirely of silica
Broken surfaces show conchoidal fracture
Identify this Sedimentary Rock 10
1cm
Comprises some clay minerals such as kaolinite and illite
Has a gritty feel when rubbed on the teeth, >10% quartz present
Identify this Sedimentary Rock 11
Well rounded flint pebbles 8mm – 6cm in diameter
Cement does not react with dilute hydrochloric acid
Identify this Sedimentary Rock 12
Rich in carbon, makes a black mark on paper
No recognisable traces of organic material evident
Identify this Sedimentary Rock 13
1cm
Grain size <1/256mm
Comprises almost entirely clay minerals, chiefly kaolinite
No bedding or laminations evident. Plastic when wet
Identify this Sedimentary Rock 14
1cm
Comprises well rounded quartz grains 0.25 – 0.5mm in diameter
Weak iron oxide cement-crumbles in the fingers (friable)
Identify this Sedimentary Rock 15
2cm
Fossil replaced
by flint
Reacts with dilute hydrochloric acid
Rock is made up of coccoliths
Identify this Sedimentary Rock 16
1cm
Reacts with dilute hydrochloric acid
Made up mainly of broken crinoid stems
Identify this Sedimentary Rock 17
1cm
Comprises entirely well rounded quartz grains 0.25–0.75mm in diameter
Very well cemented together by silica
Identify this Sedimentary Rock 18
1cm
Does not react with dilute hydrochloric acid
Has a distinct banded appearance
Identify this Sedimentary Rock 19
Comprises angular to
sub angular grains of
quartz and feldspar
Contains more than
25% feldspar
Iron oxide cement
1cm
Identify this Sedimentary Rock 20
Particle size varies
from 1mm – 4cm
Comprises fragments
of limestone, basalt,
slate and quartz
All particles are angular
Red iron oxide cement
1cm
Identify this Sedimentary Rock 21
1cm
Comprises quartz and muscovite grains
Splits readily into slabs 3-6cm thick
Identify this Sedimentary Rock 22
1cm
Reacts with dilute hydrochloic acid
Made up entirely of angular shell fragments 0.5-3mm
Identify this Sedimentary Rock 23
Has a woody ‘ring’
to it when tapped
Rich in carbon
Low density
1cm
Organic structure
clearly visible
Identify this Sedimentary Rock 24
2cm
Made up entirely of hydrated calcium sulphate
This variety is called Desert Rose
Identify this Sedimentary Rock 25
Mica flakes
concentrated on
lamination
surfaces
1cm
Contains some clay minerals, chiefly kaolinite
Over 10% quartz present plus mica flakes
Feels gritty when rubbed on the teeth
Identify this Sedimentary Rock 26
Jet black colour
Contains over
95% carbon
Vitreous lustre
Marks paper
No recognisable
traces of any
organic matter
1cm
Identify this Sedimentary Rock 27
2cm
Made up entirely of clay minerals, chiefly kaolinite
No obvious laminations or bedding present
Contains well preserved trilobite pygydium
Identify this Sedimentary Rock 28
2cm
2cm
Reacts with dilute hydrochloric acid
Has an internal concentric banded structure
Specimen obtained from the roof of a limestone cave
Identify this Sedimentary Rock 29
5mm
Spherical grains with internal
concentric structure
All parts of the rock react with dilute hydrochloric acid
Contains spherical grains of calcium carbonate over 2mm in diameter
Identify this Sedimentary Rock 30
1cm
Composed entirely
of sodium chloride
Occurs in thin, near
horizontal beds
Often grey, white
colourless, orange
or brown
Tastes salty
Identify this Sedimentary Rock 31
1cm
Composed entirely of silica
Breaks with a flat or even fracture
Specimen above has been fashioned into a cutting tool
Identify this Sedimentary Rock 32
1cm
Comprised of clay minerals and carbonaceous material
Lacks distinct laminations
Contains well preserved plant fragment
Identify this Sedimentary Rock 33
1cm
Comprises mainly quartz grains <0.25 in diameter
Brown colour due to 10-15% clay content
Contains external moulds and casts of brachiopods
Identify this Sedimentary Rock 34
Contains a high
percentage of subrounded 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
1cm
Identify this Sedimentary Rock 35
1cm
Rich in iron, hence brownish colour (limonite)
Cannot be found forming anywhere on earth today
Name this Sedimentary Rock 36
Reacts with dilute hydrochloric acid
Contains corals preserved in life position
Identify this Sedimentary Rock 37
1cm
Reacts with dilute hydrochloric acid
Made up of coccoliths
Identify this Sedimentary Rock 38
1cm
Particle size 1mm up to 8mm, quite poorly sorted
Mineralogy mainly sub-angular to sub-rounded quartz and feldspar
Identify this Sedimentary Rock 39
1cm
Reacts with dilute hydrochloric acid
May contain a small percentage of clay minerals
Identify this Sedimentary Rock 40
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