#Erosion in Ocean Basin
11 messages in this thread
Hi, Kamron–
>> Its also strange that the deep trenches haven't filled with sediment.
It is not surprising if the sediments in the trenches are continually being
pulled under with the subducting plate. The interesting question is how fast
do the sediments accumulate vs. how fast are they subducted.
–Doug
Doug
>> It is not surprising if the sediments in the trenches are continually being
pulled under with the subducting plate. The interesting question is how fast
do the sediments accumulate vs. how fast are they subducted. <<
There is a lot of variation in the sediments if the basin charts I am looking
at are true. Near the trenches around Japan there looks like a pile of
sediment on the basin side of the trench but the trench is not filled…I guess
it could be very light sediment that drifted a long way before settling.
The subduction pulling the sediment down with it is a stretch. The process
must have a very tight seam or magma would flow out so it seams as though the
sediment would be mostly scraped off and fill the trench and result in a pile
of sediment where the trenches are located.
Kamron
Hi, Kamron–
I was mostly talking about new sediment, since we were talking about rivers
from Alaska and the Aleutian trench. I do not know whether that would get
dragged under by subduction, being loose, but it would not greatly surprise me.
Bits of ooze may get caught in between where the "seal" between plates is being
formed, while most is being scraped off as you expect (but ready to try to get
caught again).
Older, deeper sediments would be lithified and just as good as the next rock at
resisting being scraped off. That has to be the bulk of the near-Japan stuff.
–Doug
Hi, Kamron–
I was mostly talking about new sediment, since we were talking about rivers
from Alaska and the Aleutian trench. I do not know whether that would get
dragged under by subduction, being loose, but it would not greatly surprise me.
Bits of ooze may get caught in between where the "seal" between plates is being
formed, while most is being scraped off as you expect (but ready to try to get
caught again).
Older, deeper sediments would be lithified and just as good as the next rock at
resisting being scraped off. That has to be the bulk of the near-Japan stuff.
–Doug
I have seen an idealised rendering of layers along the deepest NW Pacific
Trenches. I would expect a dense to fine stratification. What's your take on
them?
I remember reading of weir studies on the deposition rate of various rivers it
of earth. The measurements of the time it took to deposit the sediments were
5500 years to 11,000 for a few. Do you know of these studies?
Hi, Kamron–
Since ocean floors away from continents should collect sediments more slowly,
and because the oldest, deepest seafloors will generally have had their
carbonates redissolved, I expect thin layers for given geologic periods
compared to continental sediments.
I am not familiar with much of any river sedimentation-rate studies. Why do
you call them "weir[d] studies"?
–Doug
>> I am not familiar with much of any river sedimentation-rate studies. Why
do you call them "weir[d] studies"? <<
They are studies using weirs (troughs to divert water) for measurements of
flow and sediment content.
they found only a few thousands of years of deposits at the current rates,
which due to Man trashing the environment have probably greater sedimentation
rates than the past except of course the Great Catastrophe.<g>
Kamron
Hi, Kameron,
(If anyone else receives this message, please repost for
Kameron and let me know that my software is still wonky).
I have been thinking about your catastrophe model. The
one with an object 10 solar masses about 2 AU away. It won't
explain the formation of continents.
The tidal force of the sun right now is too weak to form
continents, right. Using inverse cube law (applicable to tidal
forces), the tidal strength of your object is only 1.25 times the
current tidal force of the sun. No rock will splinter with that!
The monopole part, which changes orbits, would be (for your
object) 2.5 times the current pull of the sun. The earth would
change orbits drastically, but not the earth's shape. Similar
analysis shows that almost any object more than a few earth diameters
away could not change the shape of the earth in any significant
fashion, and close collisions would drastically change the orbit.
Greetings David
>> I have been thinking about your catastrophe model.<<
Great! It needs all the help it can get.
The one with an object 10 solar masses about 2 AU away.<<
2 AU from the sun but it may have come within 1.25 to 1.5 AU of the earth and
Mars and much closer to the planet that was where the asteroid belt is now.
>>The tidal force of the sun right now is too weak to form
continents, right. Using inverse cube law (applicable to tidal
forces), the tidal strength of your object is only 1.25 times the
current tidal force of the sun. No rock will splinter with that!<<
If it came within 1 AU of earth then the force would be 10 times what earth
normally has. How does this look to you? The distortion of the shape of the
crust even a tiny bit would cause the fracturing.
>> Using the The monopole part, which changes orbits, would be (for your
object) 2.5 times the current pull of the sun. The earth would
change orbits drastically, but not the earth's shape. Similar
analysis shows that almost any object more than a few earth diameters
away could not change the shape of the earth in any significant
fashion, and close collisions would drastically change the orbit. <<
I think the overall mass of the earth moon system increased a tiny bit and the
orbital time increased also from 360 days to the current.
With all this in mind what do you think the sequence needs to be?
I see something like this. The star approaches reaching closest as it enters
the orbit of the asteroid belt. The earth is slowed a bit while it becomes
rerouted toward the star. As it is pulled outward the south pole at the time
was somewhere in mid pacific. The swirling oceans and mud first swirled off the
pole. Then the crust having been fractured at the old equator completley
wrenched off like the skin of a ripe fruit.
It pulled with it liquid metals from the earths interior. This put the inner
core out of balance and caused the tumbling and rapid magnetic reversals.
The removed crust or Moon closed around the metals leaving the mascons and
Mares on one side. The earth still attracted by the passing star now begins to
accelerate back up to and past the original orbital speed. The star at high
speed doesn't capture the earth or moon and they settle into the current orbit.
So any help with a set of logistics that would produce this event would be
appreciated.
I have also considered a huge meteor as the source of the catastrophe but
there is so much catastrophe evident in the solar system a huge stellar
interloper seams to solve the problem better.
10 times the tidal force currently produced by the sun on
the earth does not look strong to me. The tidal pull of the sun
is much less than the tidal pull of the moon on the earth. Rock tides
can be demonstrated (barely, by a SMALL displacement) but have never
been shown to break up any rock. We on earth hardly notice the change
in weight caused by tidal forces. 10 times is still a very weak force.
The idea of this force pulling metals, mantle, etc., around is funny.
Furthermore, with gravity, dipole (i.e., tidal) forces always
come with monopole (orbit changing) forces. I think the earth would be
pulled from its orbit.
David
>> I think the earth would be pulled from its orbit. <<
It must of been slowed and pulled out of orbit then re accelerated back into a
similar orbit.
If the star approached below the plane and closest approach to earth was
during transit with the earth ahead on approach and inbetween the Sun and star
at closest approach, then the earth could be reaccelerated and still not
achieve enough speed to leave orbit.
Kamron