Experiments on the element distribution between the granodiorite JG-1a and 2M NaCl hydrothermal solution at temperatures of 300 to 800°C and a pressure of 1 kb

Etsuo Uchida, Takuro Haitani, Takayuki Suetsugu, Takahiro Kashima, Ken Tsutsui

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The distribution of Na, K, Ca, Mg, Mn and Fe between the granodiorite JG-1a, one of the geochemical standard rocks, and 2M NaCl aqueous solution was experimentally determined at temperatures of 300 to 800°C and a pressure of 1 kb using standard cold seal-type pressure vessels. The solid run products melted partially at 800°C. Only K shows a significantly different behavior from the experiments using the basalt JB-1a (Uchida and Tsutsui, 2000) due to the presence of orthoclase in the JG-1a. The transition elements tend to be preferably partitioned into the aqueous chloride solutions with increasing temperature. At 800°C and 1 kb, the Fe concentration of the aqueous chloride solutions reached up to 5,000 ppm, and the Mn concentration up to 350 ppm. The distribution coefficient, KD,i = Ci,sol/Ci, rock, is in the order of Na>K≈Mn≈Ca> Fe≈Mg at 300°C, but changed in the order of Mn>N≈K≈Fe>Ca>Mg at 800°C. The distribution coefficients of the divalent cations for the JG-1a are higher than those for the JB-1a. The distribution coefficient of the transition elements, Fe and Mn, increases significantly with increasing temperature. The thermodynamic analysis for aqueous speciation revealed that this is attributable to the formation of the tri-chloro complexes of the transition elements at higher temperatures.

Original languageEnglish
Pages (from-to)155-161
Number of pages7
JournalResource Geology
Volume53
Issue number2
DOIs
Publication statusPublished - 2003 Jun

Keywords

  • Aqueous speciation
  • Chloride complex
  • Element partition
  • Granodiorite
  • Hydrothermal solution
  • Supercritical condition

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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