What is low sulfidation?
What is low sulfidation?
Low-sulfidation deposits form from near-neutral pH, reduced, gas-rich hydrothermal fluids. The fluids are dominated by meteoric water, but a magmatic component may play a significant role, particularly as a source of metals and ligands for metal transport in the hydrothermal solutions.
What does high sulfidation mean?
The term high-sulfidation (HS) (Hedenquist 1987) is now widely used; the term was proposed originally to refer to a fundamental genetic aspect, the relatively oxidized state of sulfur contained in the hydrothermal system (i.e., initially SO2-rich).
What is sulfidation state?
McKinstry (1959, 1963) and Barton (1970) applied the terms “sulfur content” and “sulfidation state”, respectively, to denote the relative values of the chemical potential of sulfur implied by sulfide mineral assemblages in ore deposits.
What is epithermal mineralization?
➢ Epithermal gold mineralization typically forms close to volcanic and geothermal hot spring activity, such as hot springs or geysers (Figure 3): these are the surface expression of hydrothermal systems and also, therefore, of epithermal systems.
What does epithermal mean?
Definition of epithermal 1 : deposited from warm waters at rather shallow depth under conditions in the lower ranges of temperature and pressure —used of mineral veins and ore deposits — compare hypothermal, mesothermal.
What is vuggy quartz?
A vug, vugh, or vugg (pronounced /vʌɡ/) is a small to medium-sized cavity inside rock. It may be formed through a variety of processes. Most commonly, cracks and fissures opened by tectonic activity (folding and faulting) are partially filled by quartz, calcite, and other secondary minerals.
What is a high sulphidation deposit?
High sulphidation gold systems are a unique and increasingly important type of mineral deposit. These systems are formed within a vertical continuum from shallow epithermal environments to the upper portions of porphyry copper/gold deposits.
What is an epithermal vein?
Epithermal veins are the dominant structurally controlled style of mineralization. Veins mark faults and other open fractures through which hydrothermal fluids flowed and precipitated hydrothermal phases, most commonly quartz or other silica phases and carbonate minerals.
What does arsenopyrite look like?
Arsenopyrite (IMA symbol: Apy) is an iron arsenic sulfide (FeAsS). It is a hard (Mohs 5.5-6) metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases elemental sulfur.
What does Vuggy mean?
1. adj. [Geology] Containing vugs, which are cavities, voids or large pores in a rock that are commonly lined with mineral precipitates.
What is vuggy silica?
High-sulphidation deposits result from fluids (dominantly gases such as SO2, HF, HCl) channeled directly from a hot magma. The fluids interact with groundwater and form strong acids. These acids rot and dissolve the surrounding rock leaving only silica behind, often in a sponge-like formation known as vuggy silica.
What is a low sulphidation epithermal deposit?
Low sulphidation epithermal deposits represent the uppermost (or most distal) parts of intrusion-related hydrothermal systems. They generally form within 500 metres of surface but may occasionally form between 1-2 kilometres deep. Metals are deposited at temperatures below 250
What is the pH of low sulfidation fluids?
Unlike the muddy acid waters of high sulfidation systems, the low sulfidation fluids are usually crystal clear and have a neutral to slightly alkaline pH. They look good enough to drink but often have high silica, mercury and arsenic contents along with the gold.
What is a low sulfidation vein?
Low sulfidation veins are usually well banded often with alternating layers of silica and carbonates and they frequently show brachiation or open-space filling. More importantly the nature of plates silica replacing calcite which indicates that the fluid boiled.
What are the characteristics of the lowest mineralized levels of epithermal?
The lowest mineralized levels of a LS epithermal is dominated by lead and zinc sulphides where they may form massive quartz-poor base metal-dominant veins. Due to confining pressure at these depths stockwork and breccia development is limited, unless porous lithologies permit lateral and upward flow of fluids away from the main feeder structure.
