Station 1: Bathymetric and Radiometric Evidence of Seafloor Spreading

pointdepressedMechanics

Feb 22, 2014 (3 years and 6 months ago)

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SEAFLOOR SPREADING


Station 1: Bathymetric and Radiometric Evidence of Seafloor Spreading

Observation Statements:

1.

Examine Graph 1 of the distance from the Mid
-
Ocean ridge and the ocean depth.
Provide an interpretation of what the graph is indicating.

2.

Examine Graphs 2A and 2B of the crust age and the distance to the ridge. Provide
an interpretation of what the graph is indicating.

3.

Compare Graphs 2A and 2B of the crust age and the distance to the ridge. Are there
any differences between the shapes of th
e curves? If so, provide an explanation as
to what is causing the difference.

4.

Examine Graphs 3A and 3B of the crust age and ocean depth. Provide an
interpretation of what the graph is showing.

5.

Compare Graphs 3A and 3B of the crust age and ocean depth. Ar
e there any
differences between the shapes of the curves? If so, provide an explanation as to
what is causing the difference.


Observation statement: Using the equation

of velocity, calculate in centimeters

per year:
1) the spreading rate of the

Pacific R
idge and 2) Atlantic Ridge. Use

data provided to
you earlier in Station 1

for the Pacific and Atlantic Ocean. Show

all work and do not
forget your units.

1.

Spreading rate of seafloor at Atlantic

Ridge

2.

Spreading rate of seafloor at Pacific Ridge


Observation
statement: Using the data obtained from the sea

floor depth and age
plotted graphs you will need to estimate the

AGE of the ocean crust in the Pacific using
the line of best fit in

Graph 3B. (Approximate years only.)

Depth



Age

3,000 m/9,840 ft

________
______________________

3,300 m/10,827 ft

______________________________

3,600 m/11,811 ft

______________________________

3,900 m/12,795 ft

______________________________


Station 2: Use of Sediment Thickness Patterns as Supporting Evidence of
Seafloor
Spreading

Observation Statements

1.

After completing the plot of sediment thickness and distance from

the ridge what
pattern do you observe?

2.

After completing the plot of sediment thickness and sediment age

what pattern did
you observe?


Analysis of Results:

Interpret and analyze your results for each Station by answering the following questions.

Station 1: Bathymetric and Radiometric Evidence of Seafloor Spreading

1.

Based on the plotted graphs you constructed, provide an

explanation as to what is
causing the
age of the crust to

increase the further away from the ridge.

2.

Provide a possible cause that explains the difference in spreading rates between the
Atlantic and Pacific mid
-
ocean ridges.

SEAFLOOR SPREADING


3.

Provide an explanation as to why the seafloor increases in

depth away

from the
ridge, and why it tends to level out at

great distances away from the ridge.

Station 2: Use of Sediment Thickness Patterns as Supporting Evidence of
Seafloor Spreading.

1.

Provide an explanation of the sediment thickness pattern you observed in your
graph from Station 2.

2.


Would you expect the sediment thickness away from the ridge to perfectly show the
sedimentation rate based on age? For example if the sediment rate is 1mm

every
1000 years would you expect that a 100,000
-
year
-
old crust would have exactly 100
mm of sediment on top of it?

Station 3: Paleomagnetic Banding as Supporting Evidence of Seafloor Spreading

1.

Provide an explanation that supports the magnetic banding o
bserved in the profile
you drew in Station

3


2.

Why does the magnetic banding profile show such strong

evidence for seafloor
spreading?

3.

Based on the observed data of magnetic reversals
,

what seems to be the average
number of years between the actual flips?

4.

Based on your magnetic profile do you think that mid
-
ocean ridges around the world
would show magnetic profiles that would be exactly the same? Explain your answer.


Conclude and Communicate:

1.

Present an explanation that would account for the differences in the plotted data
graphs between the Pacific and Atlantic data that was provided to you.

2.

If a mid
-
ocean ridge was to stop its production of oceanic crust, in other words the
ridge becomes dor
mant or dies out, what would you expect to observe with the
sediment thickness at the site of the ridge? Explain.

3.

If new ocean floor is constantly being produced at mid
-
ocean ridge systems, then
how is it that our planet's crust is not gett
ing larger and
the magma in the
asthenosphere is not being emptied as time progresses?

4.

Recently magnetic banding patterns have been found on the surface of Mars by
orbiting probes carrying magnetometers. What conclusions can be made by this
discovery?

5.

How important is
it that we have found some evidence of

dynamic crusts on other
worlds? Does this strengthen or

weaken the support for seafloor spreading and
continental

drift on Earth? Explain.

6.

Write two new research questions based on what you learned from this activity.