ABSTRACT
The paragenetic sequence of an ore deposit is the order of formation of the minerals. Normally it gives the time succession (i.e. oldest to youngest or earliest to latest) of events which gave rise to and affected that deposit or ore field. It should also describe the conditions under which each phase was formed or was re-equilibrated. In addition to the ore minerals, the paragenetic sequence should note the time at which the gangue minerals started to be deposited and the duration of their deposition. The sequence of events is often represented as a bar-chart diagram or flow diagram (Fig. 6.1). Picot and Johan (1982), and other European authors, use the term paragenesis as a synonym for the mineral assemblage and/or mineral associations. In this book, however, it is used only to describe a time succession. Not all ore deposits are capable of being paragenetically interpreted. For example, an ore deposit may have been subjected after its initial deposition to either prograde or retrograde metamorphism. The original depositional features may have either been destroyed or so altered as to mask or mislead an investigator studying the deposit. Some lead-zinc deposits, which are classified as being of a high-temperature origin, may in fact have deposited in a low-temperature regime, but due to subsequent metamorphic effects all the original features of a low-temperature origin may have been destroyed. Arguments as to the true nature of the initial deposition may never be resolved. Three methods, (a), (b) and (c), of representing a paragenetic sequence of ore minerals (after D.J. Vaughan and R.A. Ixer 1980; R.D. Hagni and O.R. Grawe 1964; and J.P.N. <xref ref-type="bibr" rid="ref_2">Badham <italic>et al</italic>. 1972</xref>). https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315841205/5ba85c6a-c650-48a2-85ad-93c3c6d81204/content/fig6_1_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
