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<p>Field observations from an unusual goethite orebody in northern Oman suggested that the metasedimentary host rocks were not linked to the origin of this orebody, prompting further research. Ore and surrounding carbonaceous schists were sampled along two short profiles perpendicular to the orebody (12 samples), 14 random ore samples were extracted as supplements. All materials were examined by transmitted and reflected light microscopy for their minerals and textures, semi-quantitative X-ray diffraction for the mineralogical setup, and X-ray fluorescence for their chemical compositions. The almost monomineralic nature of the ore and its appearance do not conform well to other iron deposits world-wide. Although set in a retrograde metamorphic stratigraphy, corresponding minerals are missing. However, there is ample evidence for a replacement-style ore. Field surveys and petrographic analysis show that the schists were selectively replaced along particular layers, in which calcite and most silicates were destroyed (except muscovite). The ore-forming fluids appear to have been acidic, saline, (sub-)oxic, low PT, and Fe-dominant. Chromium accumulation in the ore points to nearby mafic sills/dikes and eclogite as source rocks. This metamorphogenic goethite body likely derived from the retrograde dehydration of these rocks during exhumation. Consecutive fluid infiltration and interaction with the host rocks then precipitated the ore.</p>

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Nature and origin of the metamorphogenic as Sīfah goethite orebody (NE Oman)

  • 期刊论文

  • 发表日期：

    2026年4月8日

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  • Bernhard Pracejus,
  • Saif Al-Farsi,
  • Badar Al-Haji,
  • Norhamizah Ishak,
  • Nina Kamis,
  • Abdullah Al-Mufargi,
  • Amjid Al-Salmi

摘要

Field observations from an unusual goethite orebody in northern Oman suggested that the metasedimentary host rocks were not linked to the origin of this orebody, prompting further research. Ore and surrounding carbonaceous schists were sampled along two short profiles perpendicular to the orebody (12 samples), 14 random ore samples were extracted as supplements. All materials were examined by transmitted and reflected light microscopy for their minerals and textures, semi-quantitative X-ray diffraction for the mineralogical setup, and X-ray fluorescence for their chemical compositions. The almost monomineralic nature of the ore and its appearance do not conform well to other iron deposits world-wide. Although set in a retrograde metamorphic stratigraphy, corresponding minerals are missing. However, there is ample evidence for a replacement-style ore. Field surveys and petrographic analysis show that the schists were selectively replaced along particular layers, in which calcite and most silicates were destroyed (except muscovite). The ore-forming fluids appear to have been acidic, saline, (sub-)oxic, low PT, and Fe-dominant. Chromium accumulation in the ore points to nearby mafic sills/dikes and eclogite as source rocks. This metamorphogenic goethite body likely derived from the retrograde dehydration of these rocks during exhumation. Consecutive fluid infiltration and interaction with the host rocks then precipitated the ore.