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Title: The boron isotope systematics of the Yellowstone National Park (Wyoming) hydrothermal system: A reconnaissance

Journal Article · · Geochimica et Cosmochimica Acta; (USA)
 [1];  [2]
  1. Bristol Univ. (England)
  2. Argonne National Lab., IL (USA)

Boron concentrations and isotope compositions have been measured in fourteen hot spring waters, two drill hole waters, an unaltered rhyolite flow, and hydrothermally altered rhyolite from the geothermal system in Yellowstone National Park, Wyoming. The samples are representative of the major thermal areas within the park and span the range of fluid types. For the fluids, the B concentrations range from 0.043-2.69 mM/kg, and the {delta}{sup 11}B values range from {minus}9.3 to +4.4{per thousand}. There is no relationship between the dissolved B concentrations or isotope compositions with the concentration of any major element (other than Cl) or physical property. Each basin is characterized by a restricted range in B/Cl ratios and {delta}{sup 11}B values. Hot spring waters from the Norris Basin, Upper Geyser Basin, Calcite Springs, and Clearwater have {delta}{sup 11}B values close to that of unaltered rhyolite ({minus}5.2{per thousand}) and are interpreted to have derived their B from this source. Waters from Mammoth Hot Springs, Sheepeater, and Rainbow Springs have lower {delta}{sup 11}B values close to {minus}8{per thousand}. These lower values may reflect leaching of B from sedimentary rocks outside the Yellowstone caldera, but they are similar to the {delta}{sup 11}B value of hydrothermally altered rhyolite ({minus}9.7{per thousand}). Hence, the light boron isotope compositions recorded in these hot spring waters may reflect leaching of previously deposited hydrothermal minerals. Cooler springs along the Yellowstone River just outside the park boundary have lower B concentrations and higher {delta}{sup 11}B values that may reflect mixing with shallow meteoric water.

OSTI ID:
6026682
Journal Information:
Geochimica et Cosmochimica Acta; (USA), Vol. 54:10; ISSN 0016-7037
Country of Publication:
United States
Language:
English