EESA06H3 Lecture Notes - Lecture 4: Eurasian Plate, Olivine, Polymerization
Document Summary
Lecture 4: how oceans form: the east african rift. How continents break up and oceans open: to break apart continents, new oceans need to form. America, got smoothed and became embedded in the continent. Plates on top of them are moving though. Crust is thinned and a rift valley forms: basalt pushes crust down, red sea continent breaks into two. Basalt eruptions form oceanic crust: atlantic ocean (mature) (cid:272)o(cid:374)ti(cid:374)e(cid:374)t sedi(cid:373)e(cid:374)ts (cid:271)la(cid:374)ket the su(cid:271)sidi(cid:374)g (cid:862)passi(cid:448)e(cid:863) (cid:373)a(cid:396)gi(cid:374)s to fo(cid:396)(cid:373) continental shelves. Ocean widens and a mid-ocean ridge (mor) develops, as in the atlantic. Ocean: thick salt deposits are often found in ancient rifts, salt (cid:862)tight(cid:863), i(cid:373)pe(cid:396)(cid:373)ea(cid:271)le as it does(cid:374)(cid:859)t allo(cid:449) oil a(cid:374)d gas to es(cid:272)ape to ea(cid:396)th(cid:859)s su(cid:396)fa(cid:272)e (often why they are found under salt deposits) Decompression melting of a plume head: hot rock becomes molten magma forcing crust apart, when rocks get warm (cid:449)a(cid:374)t to (cid:396)ise.
