Easily altered minerals and reequilibrated fluid inclusions provide extensive records of fluid and thermal history: gypsum pseudomorphs of the Tera Group, Tithonian-Berriasian, Cameros Basin
This study reports a complex fluid and thermal history using petrography, electron microprobe, isotopic analysisand fluid inclusions in replacement minerals within gypsum pseudomorphs in Tithonian-Berriasian lacustrine de-posits in Northern Spain. Limestones and dolostones, formed in the alkaline la...
| Autores: | , , |
|---|---|
| Formato: | artículo |
| Fecha de publicación: | 2012 |
| País: | España |
| Recursos: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/43082 |
| Acesso em linha: | https://hdl.handle.net/20.500.14352/43082 |
| Access Level: | acceso abierto |
| Palavra-chave: | 549.76 Fluid inclusions Ypsum pseudomorphs Cameros Basin Thermal reequilibration. Mineralogía (Geología) 2506.11 Mineralogía |
| Resumo: | This study reports a complex fluid and thermal history using petrography, electron microprobe, isotopic analysisand fluid inclusions in replacement minerals within gypsum pseudomorphs in Tithonian-Berriasian lacustrine de-posits in Northern Spain. Limestones and dolostones, formed in the alkaline lakes, contain lenticularly shapedgypsum pseudomorphs, considered to form in an evaporative lake. The gypsum was replaced by quartz andnon-ferroan calcite (Ca-2), which partially replaces the quartz. Quartz contains solid inclusions of a preexistingnon-ferroan calcite (Ca-1), anhydrite and celestine.High homogenization temperatures (Th) values and inconsistent thermometric behaviour within secondary fluidinclusion assemblages in quartz (147-351◦C) and calcite (108-352◦C) indicate high temperatures after precipita-tion and entrapment of lower temperature FIAs. Th are in the same range as other reequilibrated fluid inclusionsfrom quartz veins in the same area that are related to Cretaceous hydrothermalism.Gypsum was replaced by anhydrite, likely during early burial. Later, anhydrite was partially replaced by Ca-1associated with intermediate burial temperatures. Afterward, both anhydrite and Ca-1 were partially replacedby quartz and this by Ca-2. All were affected during higher temperature hydrothermalism and a CO2-H2O fluid.Progressive heating and hydrothermal pulses, involving a CO2-H2O fluid, produce the reequilibration of the FIAs,which was followed by uplift and cooling |
|---|