1. THE DISTRIBUTION OF RARE EARTH AND TRACE ELEMENTS IN FRACTIONS OF MARINE SHALE Janet Frey D. E. Grandstaff Department of Geology Temple University Philadelphia, PA

2. Why Shale ? Shales comprise 60% or more of sedimentary rocks Shale reactions are important as sources and sinks for trace elements.

3. Element Groups (Families) Alkali EarthAlkaline EarthTransition Metals Rare EarthOther MetalsMetalloids Non-MetalsHalogensNoble Gases

4. Why Rare Earth Elements? Not much is know about mobility of REE elements in earth surface systems. REE have commonly been considered conservative in natural waters – water mass tracers. However, REE may interact with sediments. REE as analogs in nuclear waste disposal (Neptunium, Americium) Radioactive REE in short-term waste release

5. REE concentrations in bulk shales are fairly well known. However trace elements may be contained in a variety of phases: Ion exchange sites on clays Ion exchange sites on clays Adsorbed on hydrous ferric oxides Adsorbed on hydrous ferric oxides Adsorbed to organic matter Adsorbed to organic matter Co-precipitated in carbonates Co-precipitated in carbonates Bound in crystalline minerals Bound in crystalline minerals The phase in which they are contained determines their environmental mobility. (pH, redox, ionic strength)

6. Method of sequential extraction (Tessier et al., 1979) 1 gram of powdered rock EXCHANGEABLE1 m MgCl 2 CARBONATE1 m NaOAc HFO0.04m NH 2 OH·HCl - HOAc ORGANIC0.02m HNO 3 – H 2 O 2 CRYSTALLINEHF – HClO 4

7. Shale samples: Pierre Shale (K) South Dakota Navesink (K)New Jersey Hornerstown (K-T)New Jersey

8. La VA25-a VA25-b VA25-c Pb VA25-a VA25-b VA25c U VA25-a VA25-b VA25-c Replicate Analyses Ex Car HFO ORGXTL 0 2 4 6 8 10 12 14 ppm 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 ppm 0 2 4 6 8 10 ppm

9. Verendrye Total XTL Org Car Hfo La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 1 0.1 0.01 (REE/NASC)

10. Sharon Springs Sum Exch Org XTL Hfo Car La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu REE / NASC 0.01 0.1 1 10

11. Navesink Total XTL Org Hfo Car Ex La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 10 1 0.1 0.01 0.001 REE / NASC

12. Verendrye

13. 1010 30 Shale Fractionation Variable Exch Carb HFO OrganicXtl Smectite Illite Lanthanum (LREE) ppm SD-25 SD-24 VA-25 VA-24

14. ppm SD-25 SD-24 VA-25 VA-24 Gadolinium (MREE) EX Car Hfo Org Xtl

15. ppm Glauconite Ex Carb HFO OrgXtl

16. ppm

18. Sharon Springs La Gd Yb Org Ex XTL car Hfo Carb Smectite

19. La Verendrye Gd Yb org XTL car hfo Illite

20. Hornerstown La Gd Yb org XTL hfo Glauconite

21. SD-25 SD-24 VA-25 VA-24 Yttrium 0 10 20 30 40 50 ppm JHB-2 JHA-1 JN-1 0 5 10 15 20 ppm EX Car Hfo Org XTL

22. Th SD-25 SD-24 VA-25 VA-24 0 5 10 15 20 25 ppm U SD-25 SD-24 VA25 VA24 0 50 100 150 200 250 300 ppm 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 ppm EX Car Hfo Org XTL

23. U Th JN-1 JHA-1 JHB-2 JN-1 JHA-1 JHB-2 0 1 2 3 4 5 6 7 8 9 10 ppm 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 ppm

24. Conclusions Fractionation of REE/TE in shales is highly variable Depends on mineralogy, organic content In some cases <50% of REE in refractory phases Carbonate, HFO, Organic and Exchangeable fractions may provide a source of REE and TE that become mobile due to environmental changes in redox, pH and ionic strength. LREE may be less conservative than HREE; not reliable tracers. These reactions should be considered in waste disposal scenarios.

25. Thanks for listening!