Dokumen Tentang Geokimia 1

Geokimia

Pustaka Bacaan:

• Geochemistry, Brownlow, A.H. (1996)

• Introduction to Geochemistry, Krauskopf, K.B.

dan Bird, D.K. (1995)

• An Introduction to the Rock Forming Mineral, Deer, W.A., Howie, R.A., dan Zussman, J. (1978)

• Principles of Geochemistry, Mason, B. (1958)

• Majalah Ilmiah yg membahas geologi dan kimia

• Geokimia, Bronto, S. (1999)

What is unique about the Earth?

Earth is a Dynamic and Evolving Planet

• changes in its surface

• changes in life

Start of Sun-driven part of Rock Cycle: WEATHERING

 Two forms: Mechanical – fragmentation by physical process but does not change its chemical composition

Chemical – Minerals in the rock are chemical altered or changed

.

Minerals make up rocks.

Natural compounds and elements combine to form minerals.

Elements combine to form the natural compounds.

Rocks make up the Earth.

There is a hierarchy to the elements of Geology

Atoms make up elements.

Elements can be arranged, based on their identifiable properties, into the Periodic Table

Atomic Theory proposes that all matter is

composed of the atoms of about 100 different chemical elements. It further proposes that chemical

compounds are formed by the combination of the atoms of different chemical elements.

Only

eight

elements make up over

98%

of the earth’s crust

!

Na Mg K

O Al Si

Fe Ca

Geochemistry

Using rock compositions to understand their origin and evolution

• Major elements (not very useful, same information as mineralogy!)

• Trace elements

• Isotopes

Identifying magmatic processes

… using geochemistry

Definisi:

• pemerian sebaran unsur-unsur di dalam material bumi dan alasan terhadap sebaran tersebut.

• ilmu pengetahuan yg mempelajari kimia bumi

sebagai satu keseluruhan dan bagian-bagiannya.

Tujuan Geokimia:

• Mengetahui penyebaran dan kelimpahan unsur- unsur kimia dan isotop di dalam bagian-bagian bumi dan formasi geologi, baik secara kualitatif maupun kuantitatif.

• Mencari aturan/prinsip yg berlaku terhadap

distribusi dan kelimpahan unsur-unsur tersebut.

• Memahami kemungkinan adanya perubahan- perubahan aturan distribusi dan kelimpahan sebagai akibat evolusi bumi.

Cabang Geokimia:

• Atmogeokimia, mempelajari kimia atmosfer bumi

• Hidrogeokimia, mempelajari kimia air

• Biokimia, mempelajari kimia makhluk hidup

• Litogeokimia, mempelajari kimia litosfer bumi

• Kosmogeokimia, mempelajari kimia benda-benda luar bumi atau benda-benda luar angkasa

about 7,000^oC 57million psi

Not to scale

CoreMantle ?

Continental Crust

Base of lithosphere Oceanic

Crust

Atmosphere

Ocean

Plume

Mid- ocean Ridge

Relationships of volcanic activity to plate tectonics.