Inclusions in salt beds resulting from thermal metamorphism by dolerite sills (eastern Siberia, Russia)
Grishina, Svetlana; Dubessy, Jean; Kontorovich, Alexis; Pironon, Jacques
European Journal of Mineralogy Volume 4 Number 5 (1992), p. 1187 - 1202
published: Oct 14, 1992
manuscript accepted: Feb 14, 1992
ArtNo. ESP147050405025, Price: 29.00 €
Abstract Cambrian rocks in the Siberian platform, represented by carbonate-sulphate and halite beds, are intruded by numerous basaltic sills. The evolution of the fluid chemistry is described as a function of the thickness of the intrusion (h) and the distance of the sample from the contact with the intrusion (d). Four inclusion associations were found in halite as a function of the d/h ratio. The extent of the influence of intrusion is marked by the disappearance of chevron structures in halite which occurs at greater distances above than below the intrusions. For d/h less than 0.9 above the intrusion, CaCl2, CaCl2∙KCl and nCaCl2∙mMgCl2 solids occur in association with water-free and liquid- CO2 inclusions, with H2S, SCO and orthorhombic or glassy S8. For d/h between 0.2 and 2 above the intrusion, H2S-bearing liquid-CO2 inclusions are typical with various amounts of water. Sometimes, carbonaceous material and orthorhombic S8 are found. For d/h between 1 and 5 above the intrusion, the vapour phase is always a low-density CO2-bearing vapour with a volume fraction of a few percent. All these associations also occur to a smaller extent below the intrusions, indicating mainly conductive heating below the intrusions and upward vertical fluid circulation above the intrusions. This clear zonation pattern of fluid and solid inclusions as a function of d/h is probably due to the rather dry environment.