For quite some time, we have been missing some silicon.
I guess, this need some explanation. Scientists have a quite good understand of which elements should be on this earth. They derived this information from meteorites and some theoretical constructs on how earth formed from the solar nebula.
But as it’s often the case: Earth wouldn’t behave the way, models suggestes it should behave. From observation and those constructs, Earth has been missing some silicon and this has been the reason for many arguments. But geophysicists from Japan say, they’ve got an answer. Maybe you remember the post on seismic transition zones (http://on.fb.me/MQC5hv). These scientists went into the laboratory and observed seismic transition zones in the lab. Using different compositions of possible mantle material. Then they compared their findings to seismic field data (i.e. from earthquakes).
This research suggest that the earth’s mantle might be separated even stronger than it was thought until now. Nevertheless, there are large uncertainties in the temperature measurements, leaving a lot of space for argument. But maybe they found our missing silicon, buried deep deep in the lower mantle.
Read more: http://bit.ly/KV6V3T