The origin of the hydrothermal fluids in the iron-rich skarn of Colmenar-Santa Bárbara (Ossa Morena Zone)

Oxygen and carbon isotopes o f the hydrothermal minerals in the Colmenar-Santa Bárbara skarn suggest that fluids of the main hydrothermal stage (grandite/clinopyroxene and actinolite+magnetite) are of likely magmatic origin. There is only a minor input of modified surficial fluids during the late hydrothermal stages.S 34S values of sulphides indicate that sulphur derives from the hosting volcanosedimentary pile, the likely origin of most of the iron in the skarn. During hydrothermal circulation, magmatic fluids were able to recrystal Tizate and reconcentrate the magnetite and sulphides in the host rock, but without changing their major geochemical signature