1. Arcs & continents

2. Updates/questions Wednesday review, midterm on April 2nd Topics:
Systematics for:
Arcs
Some continental rocks

3. Trace Elements: REEs Enriched Depleted
Figure After Wilson (1989) Igneous Petrogenesis. Kluwer.

4. MORB-normalized Spider Diagrams
Figure Winter (2001) An Introduction to Igneous and Metamorphic Petrology. Prentice Hall. Data from Sun and McDonough (1989).

5. Trace Elements

6. Isotope Geochemistry
Isotopes do not fractionate during partial melting of fractional melting processes, so will reflect the characteristics of the source
OIBs only cross oceanic plate, limiting contamination (<-> continent); good estimate of mantle

7. Sr Isotope Evolution
Figure After Wilson (1989). Igneous Petrogenesis. Unwin Hyman/Kluwer.

8. Sm-Nd: Evolution opposite to Rb - Sr
Ctl Crust (enriched) = hi 87Sr/86Sr, lo 143Nd/144Nd
147Sm143Nd
by alpha decay
half life 106 Ga
Daughter more
incompatible
143Nd/144Nd = (143Nd/144Nd)o
+ (147Sm/144Nd)(elt-1)

9. MORB Sr - Nd Isotopes
Figure Data from Ito et al. (1987) Chemical Geology, 62, ; and LeRoex et al. (1983) J. Petrol., 24,

10. } MORB+OIB: Sr - Nd Isotopes Range in compositions = mantle array
Every composition by mixing end-members:
DM -depleted
mantle
EM 1&2 -
enriched mantle
HIMU - high m
= 238U/204Pb
238U -> 206Pb
So high 206Pb/204Pb DM
MORB }
OIB (colors)
HIMU
BSE
EM2
EM1

11. A Model for Oceanic Magmatism
Continental
Reservoirs DM
OIB
EM and HIMU from crustal sources (subducted OC + CC seds)
Figure Nomenclature from Zindler and Hart (1986). After Wilson (1989) and Rollinson (1993).

12. Arc Magmatism Volcanism in arc-shaped region of volcanoes
Different because:
Composition more diverse and silicic
Basalt generally occurs in subordinate quantities
Also more explosive than the quiescent basalts
Strato-volcanoes are the most common volcanic landform
Result of subduction: H2O melting

13. Arc occurrence

14. Structure of an Island Arc

15. Major Elements and Magma Series

16. A multi-stage, multi-source process
NOAA Ocean Explorer

17. Continental Arcs

18. Andes arc: north, central, south

19. Andes trace elements

20. Granitoid Rocks

21. Types of granites

22. Melting and composition