THIS IS A NEW SPECIFICATION
ADVANCED SUBSIDIARY GCE
F792
GEOLOGY
Rocks – Processes and Products
* O C E / 1 3 8 0 4 *
Candidates answer on the Question Paper
OCR Supplied Materials:
None
Wednesday 13 January 2010
Afternoon
Duration: 1 hour 45 minutes
Other Materials Required:
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Electronic calculator
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Ruler (cm/mm)
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9
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INSTRUCTIONS TO CANDIDATES
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Write your name clearly in capital letters, your Centre Number and Candidate Number in the boxes above.
Use black ink. Pencil may be used for graphs and diagrams only.
Read each question carefully and make sure that you know what you have to do before starting your answer.
Answer all the questions.
Do not write in the bar codes.
Write your answer to each question in the space provided, however additional paper may be used if
necessary.
INFORMATION FOR CANDIDATES
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The number of marks is given in brackets [ ] at the end of each question or part question.
The total number of marks for this paper is 100.
Where you see this icon you will be awarded a mark for the quality of written communication in
your answer.
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This document consists of 16 pages. Any blank pages are indicated.
© OCR 2010 [H/500/8417]
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Turn over
2
Answer all the questions.
1
Descriptions and thin section drawings of different rocks A to F are shown below.
thin section drawing of rock B
mica
description of rock A
•
coarse grained crystalline
texture
•
quartz is prominent
•
contains K feldspar with
some mica
2 mm
thin section drawing of rock D
quartz
grains
description of rock C
•
coarse grained crystalline
texture
•
quartz is prominent
•
mainly plagioclase feldspar
with some K feldspar
•
some mafic minerals
quartz
cement
1 mm
thin section drawing of rock F
description of rock E
•
fragmental texture
•
fine grained (<0.0625 mm)
•
layering is visible
matrix
pink mineral
with cleavage
planes
1 mm
(a) (i)
Identify the six rocks A to F.
A …………………………………
B ……………………………………..
C …………………………………
D ……………………………………..
E …………………………………
F ………………………………………
[6]
(ii) Name the texture shown in rock B.
...................................................................................................................................... [1]
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(iii)
Describe the grain shape and sorting in rock D.
grain shape.........................................................................................................................
sorting ........................................................................................................................... [2]
(iv)
Describe the environment in which rock F was deposited.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(b) (i)
State the silica content of mafic and silicic igneous rocks.
mafic ................................................... %
(ii)
silicic .................................................. % [2]
The data table below shows the characteristics of some rock forming minerals.
name
composition
specific
gravity
3–3.5
colour
black, often greenish
hornblende
Ca2(MgFeAl)5(SiAl)8O22(OH)2
calcite
CaCO3
2.7
white or colourless
K feldspar
KAlSi3O8
2.6
often pink, may be white or grey
plagioclase feldspar NaAlSi3O8 to CaAl 2Si2O8
2.6–2.8
white or grey
garnet
Fe3Al 2Si3O12
3.6–4.2
usually red or brown
muscovite mica
KAl 2(AlSi3)O10(OH)2
2.8–2.9
colourless, white or silvery
biotite mica
K(FeMg)3(AlSi3)O10(OH)2
2.8–2.9
black or dark brown
olivine
(MgFe)2SiO4
3.2–4.4
green, yellow or brown
augite
(CaMgFeAl)2(SiAl)2O6
3.4
black or greenish black
quartz
SiO2
2.65
usually white or colourless
Complete the table below with ticks to classify the minerals as mafic or felsic. Two have
been done for you.
mineral
mafic
felsic
augite
biotite mica
K feldspar
muscovite mica
✓
olivine
✓
quartz
[3]
(iii)
Using the data table, name one mineral that forms limestone.
...................................................................................................................................... [1]
[Total: 17]
© OCR 2010
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4
2
The list and the table below contain information about igneous processes and products.
(a) Complete the table by writing the correct number, 1 to 9, chosen from the list.
list
1
2
3
4
5
6
7
8
9
vesicles
the incorporation of country rock into a magma by melting
xenolith
plutonic
hypabyssal
some of the minerals in a rock melt to form a magma
the emission of magma onto the Earth’s surface where it forms a lava flow
fluid non-explosive lava
a layer of dense early formed minerals at the base of an intrusion
processes and products
definitions
extrusion
piece of country rock that is detached
and settles into the magma
assimilation
igneous rocks formed at relatively
shallow depths below the surface
effusive, low viscosity
holes formed by gases trapped in lava
partial melting
[6]
(b) (i)
Draw and label a cross section diagram to show a shield volcano.
[2]
© OCR 2010
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(ii)
Draw and label a cross section diagram to show a strato volcano.
[2]
(c) The diagram below shows a cross section through a convergent plate boundary where two
continents moved towards each other.
mountains
Earth’s surface
0
10
continental crust
20
32 km depth
temperature 850°C
(i)
(ii)
30 km
On the diagram:
• shade the area where partial melting occurs
• draw the likely position of a batholith.
[2]
Calculate the geothermal gradient at this boundary in °C/km. Show your working.
............................................................................................................................°C/km [2]
(d) Describe how a metamorphic aureole forms around a batholith.
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[Total: 16]
© OCR 2010
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3
(a) (i)
On the diagram below, shade and label where the following types of metamorphism take
place:
• contact
• regional
• burial
8
6
pressure / kbar
4
2
200
0
400
600
800
temperature / °C
(ii)
(b) (i)
[3]
Shade and label where diagenesis takes place.
[1]
Define the term polymorph.
...........................................................................................................................................
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The graph below shows an Al 2SiO5 polymorph phase diagram.
20
6
5
15
4
3
10
pressure / kbar
depth / km
2
5
1
0
200
400
600
800
temperature / °C
(ii)
Complete the diagram by writing the names of the three polymorph minerals in the
correct places.
[2]
(iii)
If all three minerals are found together in the same rock at equilibrium, state the
temperature and pressure at which metamorphism of the rock occurred.
temperature .................................................. pressure ................................................ [2]
© OCR 2010
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(c) (i)
Define the term index mineral.
...........................................................................................................................................
...................................................................................................................................... [1]
The map below shows index minerals in an area of shales that have undergone regional
metamorphism.
(ii)
Complete the map by drawing isograds to show the metamorphic zones.
GG
G
G
H
H
J
K
J
K
H
N
K
G
H
K
K
L
H
J
H
J
J
H
K
K
H
G
H
key to index minerals
L
L
J
J
K
L
J
H
J
K
K
K
K
G G
L: sillimanite
K: kyanite
J: garnet
H: biotite
G: chlorite
L
K K
H
2 km
[3]
(iii)
Complete the table below by writing the name of the rock type in which the index minerals
will be found.
index mineral
rock type
sillimanite
garnet
chlorite
[3]
[Total: 16]
© OCR 2010
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8
4
The maps below show the same part of a meandering river in 1998 and 2008.
flow
direction
N
600 m
flow
direction
N
600 m
1998
(a) (i)
(ii)
2008
Draw and label on the 2008 sketch map where erosion and deposition will have changed
the course of the river by 2018.
[2]
Explain the processes that have caused the river channel to change position.
...........................................................................................................................................
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...................................................................................................................................... [2]
(b) The diagram below shows a sedimentary structure found in a stream bed.
2 cm
stream bed
(i)
Name the sedimentary structure.
...................................................................................................................................... [1]
(ii)
Describe how it formed.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
© OCR 2010
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(c) (i)
Use a labelled diagram to explain how cross bedding can be used as a palaeocurrent
indicator.
[2]
(ii)
The table below shows measurements of cross bedding taken in sandstones to determine
the palaeocurrent direction. Complete the rose diagram by shading the appropriate
areas.
orientation (degrees
from North)
number of cross
bedding readings
1–30°
10
31–60°
15
61–90°
2
91–120°
8
121–150°
6
151–180°
4
181–210°
2
211–240°
0
241–270°
0
271–300°
0
301–330°
0
331–360°
1
rose diagram
330°
0°
15
30°
10
300°
60°
5
270°
90°
240°
120°
150°
210°
180°
[3]
(iii)
State the palaeocurrent direction.
...................................................................................................................................... [1]
(d) (i)
Draw scale diagrams to show ripple marks formed in a river channel and ripple marks
formed on a beach.
river channel
5 mm
(ii)
beach
[2]
5 mm
Draw arrows for each diagram to show the current direction.
[1]
[Total: 16]
© OCR 2010
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10
5
The diagram below shows methods of transport in water.
water surface
current
M
N
P
sediment bed
grains of sediment
(a) (i)
Name the methods of transport M, N and P.
M …………………...........………
N …………………...........………
P …………………...........………
(ii)
[3]
Name one method of transport not shown on the diagram.
...................................................................................................................................... [1]
(iii)
Name the grain sizes transported by methods M and N.
method M .......................................................................
method N ........................................................................
(b) (i)
[2]
Describe and explain the characteristics of sediments transported by ice.
...........................................................................................................................................
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...................................................................................................................................... [3]
(ii)
Name a product of deposition by ice.
..................................................................................................................................... [1]
© OCR 2010
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(c) The diagram shows grains in a sediment.
1 cm
(i)
Describe the grain shape.
...................................................................................................................................... [1]
(ii)
Draw in the box below a poorly sorted sediment.
[1]
(iii)
Explain how the roundness of grains is related to the length of time they were
transported.
...........................................................................................................................................
...........................................................................................................................................
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...................................................................................................................................... [2]
(iv)
Explain why quartz grains survive transport better than mica grains.
...........................................................................................................................................
...................................................................................................................................... [1]
[Total: 15]
© OCR 2010
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6
Describe any three of the following weathering processes:
•
burrowing
•
carbonation
•
exfoliation
•
hydrolysis
In your answer you should make clear how the rocks are broken down by each process.
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[Total: 10]
7
Describe and explain the differences between sills and lava flows. Use diagrams to illustrate your
answer.
In your answer you should make clear the comparison between these two features.
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[Total: 10]
END OF QUESTION PAPER
© OCR 2010
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Optional extension sheet. If you use this lined page to complete an answer to any question, the question
number must be clearly shown.
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