What does siderophile mean?

Definition of siderophil. : having so little affinity for oxygen and sulfur that in a molten mass the greatest concentration (as of an element) would be found in the metallic phase (as in the iron of a blast furnace) - compare chalcophile, oxyphile.

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And another question, where are chalcophile elements found?

The term chalcophile (derived from the Greek for copper-loving) was originally introduced by Goldschmidt (1923) to describe the group of elements that are concentrated in sulfide minerals in meteorites. Traditionally this group is defined as the elements Ag, As, Bi, Cd, Cu, Hg, In, Pb, S, Sb, Se, Te, Tl, and Zn. Correspondingly, which crust is thicker? continental crust Earth's crust is generally divided into older, thicker continental crust and younger, denser oceanic crust.

Moreover, does lithosphere have the same thickness everywhere?

Lithospheric plates do not have same thickness everywhere because the plates changes its thickness due to intense heat in the Earth's core as these plates move from Earth's crust and upper mantle to a deeper plasticine mantle. The lithospheric plates are thick at high elevated areas and thin at deep oceans. You can also ask why is the oldest ocean floor only 200 million years old? Most oceanic crust is less than 200 million years old, because it is typically recycled back into the Earth's mantle at subduction zones (where two tectonic plates collide).

Accordingly, why is the oldest ocean floor only 180 million years old?

If the Earth is 4.6 billion years old, why is the oldest ocean floor only 180 million years old? Because the oldest crust is destroyed at subduction zones.