Mapping Acid-Generating Minerals using Imaging Spectroscopy. Graham Ferrier Departments of Physics and Geography, University of Hull, United Kingdom

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1 Mapping Acid-Generating Minerals using Imaging Spectroscopy Graham Ferrier Departments of Physics and Geography, University of Hull, United Kingdom

2 Rationale Acid Mine Drainage impacts the quality of drinking water and health of riparian ecosystems. Identifying sources and effects of acid rock drainage is costly and time consuming Remote sensing offers potential as a rapid, low-cost monitoring tool.

3 Acid Mine Drainage Pyrite oxidation at surface produces acidic water that gradually neutralises as it drains away from the waste, depositing different Fe-bearing secondary minerals in roughly concentric zones. Fe-bearing minerals are indicators of the geochemical conditions under which they form These secondary Fe-bearing minerals spectrally unique

4 Objectives of Overall Project To determine : the optimum spatial and spectral resolutions for identifying the key iron (and clay) species the evolutionary pathways of the acid generating minerals. the relationships between heavy metal and ferruginous species Two Study Sites - Exhibiting Climate Extremes

5 Parys Mountain Extensive legacy of pits, waste tips, slag, settling ponds, and remnant natural outcrop.

6 Site 1 : Parys Mountain,Anglesey, Wales, U. K. (with Dr A. Lamb, Infoterra Ltd.) World s s largest copper producer at end of 18th Century, ceasing in Orebody displays range of exposed mineralogy typical of Volcanogenic Massive Sulphide orebodies.

7 Parys Mountain Has very high rainfall and good drainage resulting in significant dispersion of toxic material into adjacent rivers and coastal environments. Currently Largest source of heavy metals to Irish Sea Extensive Underground Workings from 16th Century onwards in very poor condition Imminent collapse of mine workings predicted with consequent dramatic increase in heavy metal output

8 Parys Mountain : Dataset Airborne Remote Sensing Hymap : SHAC m pixel resolution CASI, CASI-SWIR & ATM : & 3 m pixel resolution 3-Dimensional Digital Geological Model of Deposit 3-dimensional Map of Mine Workings

9 Airborne Remote Sensing Dataset : In 2000 : Hymap (3m) In 2002 : CASI & CASI-SWIR (1& 3m) Study Sites

10 Objectives of Parys Mountain Project Determine utility of Hyperspectral RS data in mapping mine waste mineralogy Sensitivity of spatial/spectral resolution of RS data in mapping mine waste mineralogy. CASI-SWIR vs vs HyMap Integrating surface mineralogy maps, underground mineral and mine working maps and hydro-geological models to determine localities of highest acid mine water generation

11 Study Site 2 : Rodalquilar Mining Area Epithermal Gold Deposit : mined extensively in 1950s, Last stage of exploitation involved Leachate technique

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16 Dam 1 500m Dam million m 3 of mine waste

17 Dam 1 : looking west

18 Dam 1

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20 Dam 1 Dam 2

21 Dam 2

22 Rodalquilar Mining District : Dataset Airborne Remote Sensing AVIRIS : m pixel resolution CASI & ATM : & 3 m pixel resolution * Coincident Field Spectra & Sun Photometer data

23 Processing of AVIRIS Data Atmospheric correction applied using ELT and Radiative Transfer modelling. Unmixing analysis carried out using Linear Unmixing & Matched Filter Analysis Species Spectral Identification carried out using Cross Correlation Maximum & SAM techniques

24 Total Iron Content derived from AVIRIS data

25 AVIRIS derived spectra from river

26 Unmixing Results : Mine Endmember-Jarosite

27 Spectral Analysis of AVIRIS data : Tailings Dump Endmember (m)

28 Unmixing Results : Tailings Dump Endmember - Hematite

29 Preliminary Geochemistry Results : Possible Relationships between Iron Species and Trace Metals Good Correlations between Pb and Cu & Fe concentrations from stream sediments (replicates Schwertmann & Taylor, 1989 lab. results)

30 Ba & Rb stream sediment concentrations much higher nearer to tailings dump

31 Preliminary Geochemistry Results Distribution of Sb in Stream Sediments

32 Cyanide concentration (mg/kg) Cyanide Concentration in Stream Sediments Series Sample Location Cyanide Concentrations Very high mg/kg adjacent to tailings dump

33 Rodalquilar - Preliminary Results Identified mine waste dispersion using total iron maps Differentiated iron species distributions Preliminary Geochemistry Results suggest Possible Relationship between Total Iron (and different iron species) and certain Trace metals.

34 Further Objectives of Rodalquilar Project Compare results of very high spatial resolution CASI data with AVIRIS results Understand the geomorphological/remediation history of study area Investigate the geomorphological/geochemical interactions Investigate the role and identification of clay species