Oxford Cambridge and RSA Examinations

GCE

Geology Advanced Subsidiary GCE

Unit F791: Global Tectonics

Mark Scheme for June 2012

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F79

1 M

ark

Sch

em

e Ju

ne

2012

1

An

no

tati

on

s

A

nn

ota

tio

n

Mea

nin

g

co

rrec

t res

pons

e

in

corr

ect r

espo

nse

be

nefit

of t

he d

oubt

be

nefit

of t

he d

oubt

no

t gi

ven

er

ror

carr

ied

forw

ard

in

form

atio

n om

itted

ig

nore

re

ject

Hig

hlig

htin

g is

als

o av

aila

ble

to h

ighl

ight

any

par

ticul

ar p

oint

s on

the

scrip

t.

F79

1 M

ark

Sch

em

e Ju

ne

2012

2

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

1

(a)

(i)

Con

serv

ativ

e

1

(ii)

San

And

reas

(F

ault)

/ st

rike

slip

/ tr

ansf

orm

1 A

LL

OW

Ha

ywar

d (F

ault)

or

any

othe

r co

rrec

tly n

amed

faul

t

(iii)

as

sho

wn,

Pac

ific

plat

e m

ovin

g N

W a

nd N

Am

eric

an p

late

mak

ing

SE

1 ne

ed t

wo

cor

rect

arr

ows

in c

orre

ct

dire

ctio

n A

LL

OW

bo

th a

rrow

s to

the

NW

but

ne

eds

a la

bel s

how

ing

Pac

ific

fast

er

than

the

Nor

th A

mer

ican

pla

te O

R

Pac

ific

arro

w la

rger

(iv)

(Nor

th)

Am

eric

an p

late

to th

e ea

st o

f the

faul

t P

acifi

c pl

ate

labe

lled

to th

e w

est o

f the

faul

t O

R a

nyw

here

in th

e oc

ean.

1 ne

ed b

oth

corr

ect f

or o

ne m

ark

as o

n th

e m

ap a

bove

(b

) (i)

(s

eism

ic)

tom

ogra

phy

1 D

O N

OT

AL

LO

W to

pogr

aphy

Pac

ific

plat

e N

orth

Am

eric

an p

late

F79

1 M

ark

Sch

em

e Ju

ne

2012

3

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

(ii

) (h

ot)

conv

ectio

n cu

rren

ts r

ise

OR

(ho

t) c

onve

ctio

n cu

rren

ts d

iver

ge O

R (

hot)

co

nvec

tion

curr

ents

pul

l pla

tes

apar

t OR

(ho

t) c

onve

ctio

n cu

rren

ts c

ause

di

verg

ent p

late

mar

gins

OR

rid

ge p

ush

push

es p

late

s ap

art

OR

ris

ing

mag

ma

push

es p

late

s ap

art

(col

d) c

onve

ctio

n cu

rren

ts c

onve

rge

and

sink

OR

(co

ld)

conv

ectio

n cu

rren

ts

caus

e co

nver

gent

pla

te m

argi

ns O

R s

lab

pull

mov

es p

late

s ap

art

AL

TE

RN

AT

IVE

AN

SW

ER

ho

t ris

ing

conv

ectio

n cu

rren

ts a

nd c

old

falli

ng c

onve

ctio

n cu

rren

ts

idea

of l

ithos

pher

e be

ing

mov

ed b

y th

e co

nvec

tion

curr

ents

OR

sla

b pu

ll an

d rid

ge p

ush

1

1

1 1

mar

k an

nota

ted

diag

ram

s as

text

if

men

tion

conv

ectio

n cu

rren

ts ju

st r

ise

and

sink

then

1 m

ark

ma

x lo

catio

n an

d ef

fect

= 1

(c

) (i)

ar

ea o

f the

man

tle w

hich

is e

xces

sive

ly h

ot O

R r

isin

g m

agm

a fr

om d

eep

in th

e m

antle

OR

mas

s of

mag

ma

risin

g th

roug

h th

e m

antle

1

acce

pt m

agm

a ris

ing

from

a s

peci

fic

dept

h in

the

man

tle b

etw

een

100

– 29

00 k

m

(ii

) vo

lcan

ic a

ctiv

ity a

t a fi

xed

poin

t OR

hot

spot

poi

nt a

bove

a m

antle

plu

me

OR

st

atio

nary

man

tle p

lum

e O

R e

rupt

ion

of la

va fo

rms

volc

anic

isla

nds

OR

vo

lcan

ic

activ

ity a

t a h

otsp

ot

plat

e m

oves

ove

r th

e m

ant

le p

lum

e O

R id

ea o

f isl

ands

mov

ing

away

fro

m th

e ho

tspo

t pro

duce

s a

line

of in

crea

sing

ly o

ld v

olca

noes

OR

sea

mou

nts

are

old

erod

ed v

olca

noes

OR

sea

mou

nts

are

sunk

en v

olca

nic

isla

nds

1 1

mar

k di

agra

ms

as te

xt

AL

LO

W a

nno

tatio

ns o

n m

ap

(d)

(i)

10 c

m/y

ear

+/-

0.8

cm

/yea

r co

rrec

t wor

king

di

stan

ce

510

km o

r 51

000

000

cm

t

ime

5.

1Ma

or

5 1

00 0

00 y

ears

1 1 If

470k

m th

en 9

.2

if 48

0km

then

9.4

if

490k

m th

en 9

.6

if 50

0km

then

9.8

if

510k

m th

en 1

0.0

if 52

0km

then

10.

2 if

530k

m th

en 1

0.4

if 54

0km

then

10.

6 if

550k

m th

en 1

0.8

F79

1 M

ark

Sch

em

e Ju

ne

2012

4

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

(ii

)

arro

w p

oint

ing

to N

W

1

(ii

i) ba

salt

1 A

LL

OW

ma

fic /

basi

c / b

asal

tic

To

tal

14

dire

ctio

n of

pl

ate

mov

em

ent

F79

1 M

ark

Sch

em

e Ju

ne

2012

5

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

2

(a)

(i)

colle

ctio

n of

sam

ples

of r

ock

/ soi

ls /

dust

OR

sam

ples

cou

ld b

e da

ted

OR

sa

mpl

es c

ould

be

anal

ysed

OR

sam

ples

com

posi

tion

dete

rmin

ed O

R s

how

ed

the

surf

ace

was

mad

e of

bas

alt O

R m

appe

d th

e cr

ater

s O

R e

vide

nce

of v

olca

nic

activ

ity

1 A

LL

OW

an

orth

osite

as

rock

type

(ii)

mar

ia O

R d

ark

area

da

rk a

rea

OR

(ba

salt)

lava

flow

s O

R lo

w ly

ing

flat a

reas

OR

cra

tere

d ar

ea

high

land

s O

R li

ght a

rea

light

col

oure

d O

R p

lagi

ocla

se r

ich

rock

OR

ano

rtho

site

OR

mou

ntai

nous

are

a

1 1

both

are

as n

amed

= 1

O

R c

orre

ct r

ock

in c

orre

ct a

rea

= 1

O

R n

am

e an

d de

scrip

tion

= 1

da

rk a

nd li

ght w

ith n

o na

me

then

1 m

ax

only

acc

ept d

ark

area

and

ligh

t are

a on

ce

(b)

(i)

aste

roid

bel

t 1

mus

t be

corr

ectly

spe

lt

(ii)

m

eteo

rite

type

m

eteo

rite

desc

riptio

n ca

rbon

aceo

us c

hond

rite

co

ntai

ns w

ater

and

org

anic

com

poun

ds

iron

co

mpo

sed

of a

met

allic

allo

y

ston

y

com

pose

d of

sili

cate

min

eral

s

-

2 1

OR

2 c

orre

ct =

1 m

ark

3

corr

ect =

2 m

arks

(c

)

man

tle

core

1 1

AC

CE

PT

ou

ter

or in

ner

core

T

ota

l8

F79

1 M

ark

Sch

em

e Ju

ne

2012

6

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

3

(a)

ov

erla

p du

e to

dep

ositi

on O

R o

verla

p du

e to

form

atio

n of

del

tas;

ga

p du

e to

ero

sion

; se

a le

vel c

hang

es;

fit is

at t

he e

dge

of th

e co

ntin

enta

l she

lf O

R 2

00 –

100

0 m

sub

mar

ine

cont

our

OR

at b

otto

m o

f con

tinen

tal s

lope

;

2 an

y 2

AC

CE

PT

du

e to

ero

sion

OR

dep

ositi

on

linke

d to

cha

nge

in s

hape

er

osio

n an

d de

posi

tion

with

no

deta

il =

1

max

(b)

cr

aton

s O

R s

hie

lds

OR

are

as o

f met

amor

phic

roc

ks fo

und

on b

oth

cont

inen

ts

mat

ch o

r jo

in u

p;

age

2000

– 1

000

Ma

OR

sam

e ag

e ro

cks

OR

Pre

cam

bria

n;

glac

ial d

epo

sits

OR

tilli

tes

foun

d on

bot

h co

ntin

ents

mat

ch o

r jo

in u

p;

300

- 35

0 M

a ro

cks

OR

sam

e ag

e O

R C

arbo

nife

rous

; sa

me

age

sequ

ence

of s

edim

enta

ry r

ocks

OR

lake

cla

ys O

R e

vapo

rites

OR

coa

l O

R d

eser

t san

dsto

nes

foun

d on

bot

h co

ntin

ents

mat

ch o

r jo

in u

p;

form

ed in

a d

iffer

ent c

limat

ic z

one

show

s m

ove

men

t;

2

Do

not a

war

d a

mar

k fo

r ju

st s

tatin

g th

ey

join

up

any

2 2

mar

ks m

ax

if tw

o ro

ck ty

pes

desc

ribed

1

mar

k m

ax

for

ages

A

CC

EP

T a

ny

othe

r re

ason

able

roc

k ty

pe

(c

)

sam

e tr

end

/ orie

ntat

ion

/ dire

ctio

n / a

lignm

ent /

pat

tern

of m

ount

ain

belts

acr

oss

the

join

of t

he c

ontin

ents

; st

ruct

ures

suc

h as

fold

s O

R fa

ults

mat

ch u

p;

sam

e ro

ck ty

pes

in th

e m

ount

ain

belt

mat

ch u

p fo

ld m

ount

ains

dra

wn

and

labe

lled

on th

e m

ap c

ontin

uous

ly o

n bo

th c

ontin

ents

1 1

any

1 m

ark

for

desc

riptio

n D

o no

t aw

ard

a m

ark

for

just

sta

ting

they

m

atch

or

join

up

1 m

ark

for

draw

ing

and

labe

lling

on

map

A

CC

EP

T a

ny

reas

onab

le a

rea

draw

n ov

er th

e jo

in

(d

)

dire

ctio

n of

str

iatio

ns s

how

s m

ove

men

t of i

ce O

R s

tria

tions

out

war

ds s

how

s m

ove

men

t fro

m ic

e ca

p;

1

any

1 m

ark

for

desc

riptio

n

F79

1 M

ark

Sch

em

e Ju

ne

2012

7

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

C

arbo

nife

rous

ice

shee

t acr

oss

Afr

ica

and

Sou

th A

mer

ica

OR

bot

h co

ntin

ents

w

ere

clos

er to

the

pole

; dr

awn

and

labe

lled

on th

e m

ap b

y a

rrow

s ra

diat

ing

out o

r po

intin

g w

est

1 1

mar

k fo

r dr

awin

g an

d la

belli

ng o

n m

ap

mus

t be

dra

wn

only

in s

outh

ern

part

s of

th

e tw

o co

ntin

ents

(e

)

Gon

dwan

alan

d 1

mus

t be

spel

led

corr

ectly

A

LL

OW

Gon

dwan

a

(f

) (i)

2 1

2 -

5 po

ints

cor

rect

= 1

mar

k 6

- 7

poin

ts c

orre

ct =

2 m

arks

1

mar

k fo

r cu

mul

ativ

e fr

eque

ncy

curv

e

(ii)

the

cont

inen

tal s

lope

labe

lled

from

just

bel

ow s

ea le

vel (

200m

) to

abo

ut 3

km

dept

h th

e ab

yssa

l pla

in la

belle

d fr

om 3

km –

6km

dep

th

1 1

as o

n th

e gr

aph

T

ota

l14

abys

sal

plai

n

cont

inen

tal s

lope

-

F79

1 M

ark

Sch

em

e Ju

ne

2012

8

Qu

esti

on

A

nsw

er

Mar

ks

Gu

idan

ce

4 (a

) (i)

sy

mm

etric

al s

ynfo

rm O

R s

ymm

etric

al s

yncl

ine

both

lim

bs d

ippi

ng a

t 40°

OR

with

a d

ip o

f 40°

bot

h si

des

fold

axi

s tr

endi

ng N

W -

SE

OR

fold

axi

al p

lane

trac

e tr

endi

ng N

W –

SE

;;

open

fold

; up

right

fold

axi

s;

1

1

for

nam

e A

LL

OW

1 m

ark

for

desc

riptio

n of

age

re

latio

nshi

ps

any

1

(ii)

co

mp

ress

ion

OR

com

pre

ssio

nal

1 D

O N

OT

AL

LO

W

com

pres

sive

(b

) (i)

st

rike

slip

OR

tear

faul

t si

nist

ral O

R le

ft la

tera

l; fa

ult t

rend

s N

E –

SW

;

1 1

AL

LO

W 1

mar

k fo

r de

scrip

tion

of a

ge

rela

tions

hips

an

y 1

(ii

) 51

m +

/- 1

8 m

1

this

ran

ge c

over

s m

easu

rem

ent

s us

ing

sand

ston

e or

igne

ous

rock

s an

d us

e of

all

poss

ible

di

visi

ons

of th

e sc

ale

(c

)

hors

t sho

ws

upth

row

n bl

ock

betw

een

2 fa

ults

gr

aben

sho

ws

dow

nthr

own

bloc

k be

twee

n 2

faul

ts

1 1

labe

ls c

ould

be

arro

ws

to

show

upt

hrow

and

do

wnt

hrow

th

e fa

ults

mus

t be

obvi

ous

show

ing

a cl

ear

disp

lace

men

t A

LL

OW

1 m

ark

ma

x fo

r tw

o co

rrec

t dia

gram

s w

ith n

o la

bels

fo

r 2

mar

ks n

eed

2/3

of

faul

ts, a

rrow

s or

mar

ker

bed

show

n fo

r 1

mar

k ne

ed 1

/3

norm

al

faul

ts

grab

en

ho

rst

F79

1 M

ark

Sch

em

e Ju

ne

2012

9

Qu

esti

on

A

nsw

er

Mar

ks

Gu

idan

ce

(d

) (i)

bo

th a

xial

pla

nes

mus

t be

draw

n an

d at

leas

t one

labe

lled

1 ax

ial p

lane

line

s m

ust e

xten

d th

roug

h a

min

imum

of t

hree

be

ds

(ii)

see

diag

ram

abo

ve

cres

t at t

op o

f ant

iform

tr

ough

at b

otto

m o

f syn

form

/ at

low

est p

oint

of t

he fo

ld

limb

on s

ides

of f

old

2

limb

in a

ny p

art o

f fol

d th

at is

no

t the

cre

st o

r tr

ough

1-

2 co

rrec

t =1

mar

k 3

corr

ect =

2 m

arks

(iii)

Wes

t 1

AL

LO

W le

ft

(iv)

over

fold

1

cres

t tr

ough

ax

ial p

lane

F79

1 M

ark

Sch

em

e Ju

ne

2012

10

Qu

esti

on

A

nsw

er

Mar

ksG

uid

ance

(e)

corr

ect s

hape

for

both

(ci

rcul

ar o

r ov

al)

= 1

ol

dest

and

you

nges

t cor

rect

for

both

= 1

at

leas

t 3 c

orre

ct d

ip a

rrow

dire

ctio

ns fo

r bo

th =

1

3

if a

cros

s se

ctio

n is

dra

wn

then

max

1 if

ant

iform

dra

wn

for

dom

e A

ND

syn

form

dr

awn

for

basi

n if

a 3D

dia

gram

is d

raw

n th

en m

ax 1

if d

ome

and

basi

n ar

e co

rrec

t

T

ota

l16

old

est

youn

gest

youn

gest

youn

gest

old

est

old

est

old

est

olde

st

F79

1 M

ark

Sch

em

e Ju

ne

2012

11

Qu

esti

on

A

nsw

er

Mar

ks

Gu

idan

ce

5

co

nve

rgen

t p

late

mar

gin

des

crip

tio

n

B

enio

ff zo

ne O

R li

near

zon

e of

ear

thqu

akes

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the

plat

e m

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n O

R b

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fo

ld m

ount

ains

at c

ontin

enta

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sh

allo

w fo

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(0-7

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to th

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at t

he to

p of

the

subd

uctio

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R

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p fo

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m th

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(70

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hallo

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hallo

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bel

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oc

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tow

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how

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MO

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an

y 2

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max

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dive

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t m

argi

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T

ota

l8

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