Lecture ONE Introduction

Introduction

The composition of the Earth:

-Lithosphere (5-70 km, solid and rocky, 5 km thick under the oceans and up to 70 km thick under the continents). It composes of:

- sedimentary cover (10 km)

-Sial (granitic in composition)

-Sima (basaltic in composition)

-Mantle Asthenosphere (250 km thick, molten rocks, 780 °C)

-Mantle Mesosphere (2550 km thick, Si, O, Fe, Mg)

-Outer core (2200 km thick, Thick liquid, Fe, Ni)

-Inner Core (1228 km thick, Solid, Fe and Ni)

Rock cycle

RocksRocksRocks are defined as a component of the Earth’s crust, composed of one are defined as a component of the Earth’s crust, composed of one or more minerals with geologic extensionor more minerals with geologic extension

Rocks are classified intoRocks are classified into::

- - PrimaryPrimary - Igneous rocks- Igneous rocks

- - SecondarySecondary - Sedimentary rocks- Sedimentary rocks

- Metamorphic rocks- Metamorphic rocks

-The metamorphic rocksThe metamorphic rocks are secondary rocks formed from pre-are secondary rocks formed from pre-existing igneous, sedimentary, and/or prior metamorphic rocks, which are existing igneous, sedimentary, and/or prior metamorphic rocks, which are subjected to physicochemical conditions (subjected to physicochemical conditions (P, T, and chemical active fluidsP, T, and chemical active fluids) ) higher than that at the earth’s surface. The yielded metamorphic rocks differ higher than that at the earth’s surface. The yielded metamorphic rocks differ than the original ones in than the original ones in mineralogy, structure (textures), and/or chemical mineralogy, structure (textures), and/or chemical

compositioncomposition. . Note:Note: Metamorphism should be occur in solid state Metamorphism should be occur in solid state..

-Due to higher P-T conditions, metamorphic rocks undergo partial melting Due to higher P-T conditions, metamorphic rocks undergo partial melting and a hybrid rock between igneous and metamorphic, know as and a hybrid rock between igneous and metamorphic, know as

migmatitesmigmatites, could form. , could form.

Continental drift

Plate boundaries

Plate boundaries

Plate Motions

Types of the Plate motion

Plate boundaries includes:

i- Divergent plate boundaries (i- Divergent plate boundaries ():):

- Formation of the Red Sea and Atlantic Ocean

Ii- Convergent plate boundaries (Ii- Convergent plate boundaries ())

-Oceanic-continental convergence (Oceanic Nazka – S American plate)

- Oceanic-oceanic convergence (Pacific plate – Philippine plate)

-Continental-continental convergence (Indian plate- Eurasian plate)

iii- Transform or shear plate boundaries:iii- Transform or shear plate boundaries:

- The San Andreas fault zone, and Gulf of Aqaba fault

i- Divergent plate boundaries

i- Divergent plate boundaries, Cont.

i- Divergent plate boundaries, Cont.

ii- Convergent plate boundaries

ii- Convergent plate boundaries, Cont.a) oceanic-oceanic subduction

ii- Convergent plate boundaries, Cont.b) Oceanic-continental subductionb) Oceanic-continental subduction

ii- Convergent plate boundaries, Cont. c) Continental - continental collisionc) Continental - continental collision

iii- Transform or shear plate boundaries

iii- Transform or shear plate boundaries, Cont..

Why we study metamorphic rocks?

Goals of study metamorphic petrology includes:

- Academic goals: to deduce the followingAcademic goals: to deduce the following

- Protolith (original rock) composition

- Grade and conditions of metamorphism

- Tectonic setting under which the metamorphism have done

- Applied goals:- Applied goals: Metamorphic rocks like other rock types hosted

mineral resources e.g:

- Graphite, Talc, Magnesite, Asbestos, Corundum, vermiculites,

garnets, etc.

- They used also as ornamental stones as Slates, Marbles,

gneisses, metaconglomerates, greenstones and others