NExUS Professional Development Workshops: Field assessment of gossans and leached outcrops
NExUS Professional Development Workshops
Online Workshop
Field assessment of gossans and leached outcrops
(Theory, general procedures and specialised techniques).
Date & Time
4th May 2021
(Limited to 30 places)
The proposed online workshop will include 4 x 90 minute sessions covering
Presented by
Dr Roger Taylor and Dr. Richard Lilly
Dr Roger Taylor has been involved with the exploration industry for over 50 years operating as a practicing exploration/mine geologist and academic as Director of the Economic Geology Research Unit at James Cook University (1993-1998).
More recent activities include international consulting to numerous global mining companies, further development of a range of professional development courses, and petrological services.
Major publications include books on tin deposits, ore textures-breccias, and gossans/leached outcrops.
Major interests are magmatic related deposits, including tin, wolfram, porphyry copper, IOCG, and epithermal systems.
Dr. Richard Lilly is a senior exploration geologist with over 20 years’ experience spanning the industry-academia boundary. Working for Mount Isa Mines (2007-2015) and as an Embedded Research Fellow at the University of Adelaide he has coordinated and supervised >50 applied research investigations on a diverse range of ore deposits from North West Queensland to South Australia.
The proposed online workshop will include 4 x 90 minute sessions covering
- The principles and practices required for the visual field-scale assessment of leached outcrops for a range of deposit types.
- Special emphasis is placed on the surface expression of porphyry copper styles and their related oxide zones.
- Gossan/leached caps general.
- Basic principles of oxidizing profiles above ore zones.
- Types of gossans and leached cappings – recent discoveries.
- Coping with limonites: styles, compositional effects of neutralizing wall rocks, indigenous versus transported.
- Secondary mineral recognition and factors governing their formation. Emphasis on copper
oxide grouping. Interpretation of assemblages (Cu, Pb, Zn, Fe, Ni, Ag)
- Boxworks recognition, mode(s) of development, overprinting effects. Rock versus sulphide
styles
Session 1: General Broad Scale Aspects.
- Theoretical perspectives.
- Types of leached capping and gossans.
- Structural preservation.
- Limonite types and terminology.
Session 2: Secondary Minerals and their interpretation.
- Fe,Mn.
- Cu,Pb,Zn, As.
- Ni,Co,As,Sb,Mo,Bi,W,A,U.
Session 3: Boxworks and related features.
- Model(s) of development,
- Overprinting effects.
- Rock versus sulphide styles.
- False boxworks.
Session 4: Porphyry Copper-Leached cap assessment
- Supergene enrichment, factors controlling profile development, relationships to leached
caps, influence of overprinting high-sulphidation systems.
- Surface expressions (mature versus immature profiles).
- Examples from arid (Escondida) and tropical (Grasberg) environments.
- Oxide zones, factors governing development, different types of oxide zones, mineral
recognition.
- Approach to assessment-limonite style interpretation.
- Overview of approach and expectation.
REGISTRATION FEES
Full Registration: $250
AIG Members: $200
Students: $50
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