Mass transfer during wall-rock alteration: An example from a quartz-graphite vein, Black Hills, South Dakota

Journal Article · Fri Jul 01 00:00:00 EDT 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90014-2· OSTI ID:5181330

Galbreath, K C; Duke, E F; Papike, J J ^[1]; Laul, J C ^[2]

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1. South Dakota School of Mines and Technology, Rapid City, SD (USA)
2. Pacific Northwest Laboratories, Richland, WA (USA)

Mass transfer and fluid-rock interaction have been evaluated along two sample traverses in low-sillimanite grade quartz-mica schist adjacent to a synmetamorphic quartz-graphite vein in the southern Black Hills, South Dakota. In an {approximately}17 cm halo between apparently unaltered schist and the vein contact is an outer zone of cryptic alteration and three inner zones of visible alteration. The cryptic zone consists of the original prograde metamorphic mineral assemblage plus anomalously high amounts of tourmaline. The outermost visible zone contains abundant graphite. The second visible zone is defined by intensive bleaching of the schist. The innermost visible zone, immediately adjacent to the vein, is tourmaline + quartz + plagioclase + limonite + graphite. The vein is composed almost entirely of quartz, but also contains trace amounts of graphite. Mass balance calculations indicate that Al was essentially inert. The predominant chemical changes during wall-rock alteration were addition of B and C from the vein-forming fluid along with loss of K from the wall rocks, corresponding to precipitation of tourmaline and graphite, and the progressive destruction of microcline, biotite, and muscovite toward the vein. In addition, the elements V, Cr, Cu, Zn, Pb, As, Sb, W, and Au were introduced into the country rock, whereas Si, Rb, Ba, and Cs were removed. Fluid-rock interaction modeling suggests that between one and four equivalent masses of fluid interacted chemically with the most altered mineral assemblages. In addition, greater than one equivalent mass of reactive fluid penetrated to distances of at least 5 cm from the vein contact.

• DOE Contract Number: FG01-84ER13259; AC06-76RL01830
• OSTI ID: 5181330
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 52:7; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
SCHISTS
CHEMICAL COMPOSITION
HYDROTHERMAL ALTERATION
MINERALOGY
SOUTH DAKOTA
GEOCHEMISTRY
GEOLOGIC HISTORY
GRAPHITE
MASS BALANCE
MASS TRANSFER
PETROGENESIS
QUARTZ
ROCK-FLUID INTERACTIONS
CARBON
CHALCOGENIDES
CHEMISTRY
ELEMENTAL MINERALS
ELEMENTS
FEDERAL REGION VIII
METAMORPHIC ROCKS
MINERALS
NONMETALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
ROCKS
SILICON COMPOUNDS
SILICON OXIDES
USA
580000* - Geosciences