Mineral recorders of pegmatite internal evolution: REE contents of tourmaline from the Bob Ingersoll pegmatite, South Dakota

Journal Article · Sat Aug 01 04:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90272-9· OSTI ID:5127719

Jolliff, B L; Papike, J J

Trace rare earth elements (REE) have been determined by radiochemical neutron activation analysis for tourmaline samples from an internally zoned, rare-element, granitic pegmatite, located in the Black Hills, South Dakota. The Total REE concentrations range from 40 ppm-0.2 ppm, and are highest in tourmaline from the exomorphic halo (country rock) and pegmatite border zone. Chondrite-normalized patterns are highly fractionated from light REE to heavy REE; and REE concentrations decrease in tourmaline from the outer wall zone and first intermediate zone, through the inner wall zone and third intermediate zone, to lowest levels in the pegmatite core. The REEs, as recorded by tourmaline, appear to behave compatibly in this pegmatite system due to early crystallization of apatite and other possible REE-sink minerals. The large range of REE concentrations and differences in slopes of chondrite-normalized patterns probably also reflect significant changes in the structural state of the pegmatite melt, caused by changes in pH/sub 2/O and other volatiles (B, F, P) as crystallization progressed. Tourmaline samples that appear to have been fluid-derived are HREE-depleted relative to coexisting silicate-melt-derived tourmaline. Tourmaline does not exhibit any strong preference for specific REEs, rather its REE content appears to reflect the REE content of the medium from which the tourmaline crystallized.

• Research Organization: South Dakota School of Mines and Technology, Rapid City (USA)
• DOE Contract Number: FG01-84ER13259; AC06-76RL01830
• OSTI ID: 5127719
• Journal Information: Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 51:8; ISSN GCACA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
ACTIVATION ANALYSIS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BORON COMPOUNDS
BORON SILICATES
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
CRYSTALLIZATION
ELEMENTS
FEDERAL REGION VIII
GEOCHEMISTRY
GRANITES
IGNEOUS ROCKS
METALS
MINERALOGY
MINERALS
NORTH AMERICA
OXYGEN COMPOUNDS
PEGMATITES
PHASE TRANSFORMATIONS
PLUTONIC ROCKS
RARE EARTHS
ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SOUTH DAKOTA
TOURMALINE
TRACE AMOUNTS
USA