Plate Motions and Triple Junction
Insure that you understand the difference
between relative and absolute plate motions. For this lab
we will deal with the relative motions between pairs of plates.
You may do this lab individually or in groups. You will be tested on it
during a quiz next week.
- Change program version to
- Open the help file, and read the section on
Junctions Computations. It contains analyses
of the Indian Ocean triple junction. and the
Gulf of California
triple junction. Note that it describes
using geometric and analytic solutions . You should
use the geometric option.
- File, Structural Geology lab, triple junctions.
- Analyze the following triple junctions. You
should do this with the HS3-NUVEL-1A plate model since it has more
plates included. You can verify the motions with a
web plate motion calculator.
- The Nazca--Cocos--Pacific triple junction
- The triple junction at S45, W76.
Charlotte Triple Junction, in British Columbia, at about N51. You can use the Juan de Fuca
Plate motion since none of these models includes the Explorer plate.
Plate motion calculators,
if you want to check results or use an alternative method.
Deliverables: each triple junction you should
- Velocity stability diagram. It should be approximately
correct; you can estimate the velocities and angles.
- Nature of the triple junction (ridge-ridge-ridge, etc.)
- Is the triple junction stable, and if so, will it be
migrating. If it is not stable, how large a change would be
required to make it stable.
- Include a map with the ages of the seafloor, and an elevation map from
ETOPO1 to explain the relationships.
Triple junctions used in previous semester
The Philippine--Pacific--Eurasian triple junction
SE of Japan. Some scientists think the
Eurasian--North American plate boundary is west
of its location on the map in MICRODEM (for instance Map of the plates), and that this triple
junction is actually Philippine--Pacific--North
America. Repeat the calculations for this
configuration, and does it make much difference
(i.e. what are the relative plate velocities
between North America and Eurasia in this
region?) Repeat the calculations for the APKIMA
Last revision 9/29/2015