Sedex (sedimentary exhalative) Pb-Zn

The following sedimentologic/diagenetic/meta-evaporite criteria clearly separate the three deposit styles tied to evaporite associated seder deposits, namely; 1) the nature of the associated CaSO4 (depositional beds versus burial diagenetic verses hydrothermal in an igneous-rich matrix), 2) tectonic settings that facilitate thick bedded halite deposits- thick halite cannot precipitate at open ocean basalt ridges. At continent-continent proximal young-oceanic ridges , the halite must be halokinetic - as in the hydrothermal Atlantis II deep, 3) solution chemistry and characteristics of sulphide and non-sulphide cements in the associated breccias in the immediate vicinity of ore lenses (warm in diagenetic (<200-250°C; versus hot >250-300°C) in igneous VMS associations. The differences in these three factors are indicators of the specific ore system; as is the nature of the surrounding non-ore matrices, as well as the type and geometry of the alteration residues. In addition, differences in ionic proportions seen in the hydrochemical details, captured in fluid inclusions, are pointers to the ultimate brine source. In combination, all these factors can be used to separate the three deposit styles (see Warren, 2016; Chapter 15).


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