Hydrothermal alteration and fluid inclusion study of the Lower Cretaceous porphyry Cu–Au deposit of Tiámaro, Michoacán, Mexico

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• 作者：Carlos Garza-Gonz&#xe1 ; lez ; Antoni Camprub&#xed ; Eduardo Gonz&#xe1 ; lez-Partida ; Germ&#xe1 ; n Arriaga-Garc&#xed ; a and Fernando Rosique-Naranjo
• 关键词：Ti&#xe1 ; maro ; Mexico ; Porphyry Cu– ; Au ; Hydrothermal alteration ; Fluid inclusions
• 刊名：Journal of Geochemical Exploration
• 出版年：2006
• 出版时间：April-June 2006
• 年：2006
• 卷：89
• 期：1-3
• 页码：124-128
• 全文大小：364 K

文摘

The Tiámaro deposit in Michoacán state has been dated as Lower Cretaceous (Valanginian), though most of the porphyry deposits in central Mexico were dated or have an attributed Eocene–Oligocene age. The host rocks belong to a volcanoplutonic complex overlain by red conglomerates. These rocks were intruded by pre-Valanginian plutonic and hypabissal rocks. Propylitic, phyllic, and argillic alteration assemblages developed, and their superimposition draws the evolution of the deposit. Stage I is represented by propylitic assemblages, stage II contains the main ore forming stockworks and both phyllic and argillic assemblages, and stage III contains late carbonatization assemblages. The obtained temperatures and salinities from inclusion fluids are low for a porphyry-type deposit, but we interpret that the known part of the deposit represents the shallow portion of a bigger deposit. The evolution of mineralizing fluids draws a dilution trend of brines from “porphyry-like” to “epithermal-like” stages. The richest ore zone is roughly located between the 300 and 350 °C isotherms, though unnoticed resources may occur at depth.