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Hawaiian hotspot and plume - Coggle Diagram
Hawaiian hotspot and plume
magnetic filings
rock magnetism recorded plate movement
magnetism from magnetic minerals in igneous rocks
magnetite
titanomagnetite
can be recorded by
magnetic field reversals
creates stripes of rocks with different polarities and ages
time and distance data to calculate direction and speed
earth's magnetic field
declination(horizontal)
inclination(vertical)
directly related to latitude
can find minimum distance travelled
difficulties
many young islands whose rocks aren't old enough
can drill into ocean floor
having to drill into the ocean floor(may run into financial issues)
false positives may surface from tilting of crust
can confirm flatness using seismic data
measuring magnetization remotely may see interference
magnetometers can be calibrated against sample rocks to an extent
wide latitude
reports of movement of the hotspots in 1970s
studied stripes in rock, island chains
prediction was not accurate
refined by another team, gaining agreeing results
other geologists did not agree, stated possible issues
movement traces back 60 million years
new magnetic analysis conducted on existing rock sample using new technology (shielded superconducting quantum interference device)
sample JUST about enough to determine location
matching these results with existing results from previous teams' works from other institutions supported the argument of moving seamounts
pole position
polar wander
definition: the concept where the earth's magnetism and spin is stationary in space, and that it is landmass and matter that moves
this concept assumes that hotspots are fixed in space, allowing reconstruction of plate movement and be able to accurately predict where locations would have been from the earth's spin
data from this suggested that landmass migrated 20 degrees over 130 million years
now that hotspot fixity is disproven, it implies that past data may be wrong, and that hotspots may not be accurate for plate movement reconstruction
hotspot position may be stationary in deep mantle, but fluid from what can be proven
past theories and explanations cannot be simply disproven due to new findings, more research must be done on both plate and hotspot movement to determine roles and contributions
new expedition to get new rock samples
seismic survey's conducted to ensure flat orientation of rocks
multiple researchers from different institutes gathered
magnetism was surveyed on the ship
allowed rough findings in early stages
findings had to be confirmed over several months after expedition
consensus was mostly reached upon return
findings show that the researched hotspot was moving south quickly at a rate of more than 4cm a year
no traces of corals at some sites proved that the islands didn't form around the latitude at which it currently is
sediments did not match the expected carbon-rich composition of hotspots created in that area
initial observations
unable to locate cone where it usually would be
initial thoughts
plate tectonics?
hotspot did not move, tectonic plates did