geochemistry 2012
TRANSCRIPT
Tanta University Faculty of Science
Department of Geology
Geochemistry 2012 4th year- 2nd term
Submitted byMohamed Mahmoud Ahmed El-Shora
Isotopes
REE
Mineral Chemistry
Geochemistry
Isotopes
IsotopesMineral Chemistry
REE
Radioactivity (Isotope)
• Isotope analysis• Isotope: are atoms having the same atomic number “Z” but different
masses “A” due to difference in number of neutrons “N”.• Ex:
• Isobars: atoms having the same mass “A” but different “Z” and “N”.• Ex:
• Isotones: atoms having the same “N” but different “A” and “Z”.• Ex:
Isotopes
Stable isotopes
Unstable isotopes
Stable isotopes
• Atoms do not change into other atoms, but the only change is the number of “N”
• Have low life time • Ex: O, H, S, C, N• عدد في لتغير نتيجة العنصر لنفس نظائر ايالنيترونات
• Parent atom is changed into daughter atom U……….P
• Associated with the emission of α, β, µ• Have great life times• Ex: Sr, Rb, U, Pb• Present decay process• لعملية نتيجة اخر لعنصر عنصر من يتغير العنصر اياالشعاع
Unstable isotopes
Geochronology • Another importance of
radiogenic isotopes is usage of them is age dating of rocks.
• This can be done using the isochron diagram.
• Rubidium – Strontium system
Parent atom is changed into daughter atom U……….P
Isochron diagram
• τ= 1/λ ln ( slope +1)• Where: τ the age λ the decay constant
Ex:
القيم عمودمتشابهه الغير
المتشابهه القيم عمود
Select data, then press insert
Press Scatter
Right-click on the points
The Result
• τ= 1/λ ln ( slope +1)
• القانون هذا عوضفيالعمر هو والناتج
The End Of Isotopes
REE
Mineral Chemistry
Isotopes
REE
Man
tle Residual“HREE”
Melt“LREE”
Partly melting
Types of melting
• 1- Fractional Melting When melt leave magma chamber without react with residualSo HREE ˃ LREE• 2- Batch Melting When melt still in magma chamber and react with residualSo LREE ˃ HREE
1Fractional Melting
HREE ˃ LREEشديد الخط انحدار
BATCH MELTINGLREE ˃ HREE
خفيف الخط انحدار
Normalization
EuLa Lu
LREE HREE
Normalization = conc in rock / conc in PM
PM : Primitive Mantle
1Enrichment
Depletion
Metasomatism“Rock was attacked by
Melt”
REE
1
2
1
2
Press here
1
2
After inserting the the value of
each element
press "Enter"
1
2
After inserting the the value of
each element
press "Enter"
1
2
1
2
3
1Fractional Melting
HREE ˃ LREEشديد الخط انحدار
BATCH MELTINGLREE ˃ HREE
خفيف الخط انحدار
Normalization
EuLa Lu
LREE HREE
Normalization = conc in rock / conc in PM
PM : Primitive Mantle
1Enrichment
Depletion
Metasomatism“Rock was attacked by
Melt”
Enrichment
Depletion
Metasomatism
BATCH MELTING
BATCH MELTING
Mineral Chemistry
Isotopes
REE
Calculate the general formula of group of mineral “Manual”
• The following steps must be performed:• 1-calculation of the molecular proportion (M.P) M.P=(WT%/Mwt)*1000• 2-atomic proportion (ATP) ATP=M.P*no of (O) oxygen atoms in oxide• 3-Factor (F) F=no of (O) in general formula/Sum of ATP• 4-Number of anions = F*ATP• 5-Number of Cations = no of anions*(no of cations/no of (O) in each oxide)
Notes
• 5-Number of Cations = no of anions*(no of cations/no of (O) in each oxide) EX
• (no of cations/no of (O) in each oxide)= 1/2
SiO2
General Formula• Pyroxene Group
• Feldspar Group
• Amphibole Group
Pyroxene Group
Feldspar Group
Types of Feldspar:
General Formula
Feldspar Group
Feldspar Group
Amphibole Group
Example for Amphibole Group
Sample 2 Sample 1 Oxides
52.05 53.44 SiO2
0.21 0.23 TiO2
2.02 1.29 Al2O3
12.24 9.11 FeO
0.27 0.16 MnO
10.52 15.25 MgO
23.75 20.24 CaO
0.44 0.51 Na2O
Example for Pyroxene Group
Example for Feldspar GroupSample 2 Sample 1 Oxides
64.1 65.98 SiO2
- - TiO2
22.66 19.58 Al2O3
0.14 - Fe2O3
0.17 - FeO
- 0.21 MnO
0.25 0.12 MgO
3.26 0.49 CaO
9.89 5.9 Na2O
0.05 7.88 K2O
Minpet 2.02
To Create File
Enter the data for the sample No. one
After inserting the the value of
each element
press "Enter"
Enter the data for the sample No. two
After inserting the the value of
each element
press "Enter"
or
To calculate the general formula from minpet
Press here
T=Z , M1=Y , M2=X
5-Number of Cations = no of anions*(no of cations/no of (O) in each oxide)
T=Z , M1=Y , M2=X
P-T Condition In Pyroxene sample
Ca
FeMg
Cations بـــــ بشتغل
recalculation
In Pyroxene sample
PL-Amphiboleالقانون في بيها واعوض طلعت اللى الكاتيون نسبة باخد
الرسم في واوقع
PL-Amphibole
Amphibole onlyWt%
Amphibole only
• Wt% بـــــــ بنشتغل• العينة هي التقاطع نقطة• الـــ واشوف انزل• Temp & Pressure• يكون ان البد التوقيع
للخطوط موازي.األساسية
IsotopesMineral Chemistry
REE
Best RegardsMohamed M Elshora
President of AAPG-TUSCPhone (+2)01112078926 OR (+2)01280048933Mail : [email protected]