Energy Critical Elements in the English - , North

Giulio Solferino & Nathan Westwood

3rd International Critical Metals Conference – Edinburgh, April 29 –May 03, 2019 Contents

‐ Introduction

‐ Scar Crags and Dale Head North

‐ Geology

‐ Minerals & Paragenesis

‐ A story of magma and sediments

‐ Oddities Introduction

2017 Critical Raw Materials Antimony Fluorspar LREEs Phosphorus Baryte Gallium Magnesium Scandium Beryllium Germanium Natural graphite Silicon metal Bismuth Hafnium Natural rubber Tantalum Borate Helium Niobium Tungsten Cobalt HREEs PGMs Vanadium Coking coal Indium Phosphate rock

Taken directly from the European Commissions most recent (2017) critical materials review.  27 different raw materials are now considered to be ‘critical’ according to the Commission which has increase by 9 from the last review (2014) Introduction

Olivetti, E. A., Ceder, G., Gaustad, G. G., Fu, X., Joule (2017), 1, 229. Introduction

• The UK relies almost entirely on EU and other international sources for its Co supply. Yet, there might be viable sources within the British Isles.

• Noticeably, in the Lake District several Co‐bearing https://www.euchems.eu/wp‐ mineralisations were flagged (back in the seventies and content/uploads/2019/01/The‐Periodic‐Table‐and‐ us‐Handley‐European‐Commission.pdf eighties) Introduction

Why? Lake District is host to a vast network of high quality mineral deposits which have not been studied for a number of years. Also, easily accessible.

Many of the mineral deposits are unique and have very unusual geochemistry

W (wolframite and scheelite at Carrock Mine), Sb (Stibnite and berthierite at the Robin Hood and Wet Swine Gill veins) and pure graphite (C, in the form of nodules within metamorphosed veins at Seathwaite/). Introduction Scar Crags and Dale Head North

Where? Northern ‘English Lake District’ Scar Crags and Dale Head North Group Formations  Early‐mid mostly epiclastic sedimentary rocks

Borrowdale and Eycott volcanics  Mid‐late Ordovician mostly volcanics (lava, tuff, ignimbrite)

Largely concealed batholith  Late‐Ordovician to Mid‐Devonian

Map inspired by: Earthwise.bgs.ac.uk, 2017 Fault Geology Scar Crags: Hosted by Kirkstile Fm. ()

Siltstone and mudstone

‘Bleached’ shales Metasomatic aureole of intrusive synchronous to the Shap Granite.

Causey Pike Fault Geology

Dale Head North: Hosted by Fm. (Skiddaw Group) Siltstone, mudstones, and sandstones.

 Fluids that forms veins must cross through all surrounding/underlying rocks

 At DHN some of those rocks are tuffs and ignimbrites (BVG) Minerals & Paragenesis

New findings:

 Sulpharsenides are solid‐solutions of Co‐Fe‐Ni  There are REE minerals  Gold  Bismuth in large amounts

So, what critical elements? As, Bi, Co, REE, Sb, Se*, Te*

*There are some unidentified Bi‐Te and Bi‐Se Qz Minerals & Paragenesis Cpy Aln

Chl Aln Microphotograph: RL, XPL Sph

All 0.5 mm

Apy Gla Microphotograph: RL, PPL Cob

All All

1 mm Minerals & Paragenesis Minerals & Paragenesis Sulpharsenides –S‐bearing Silicates, etc. –S‐free A story of magma and sediments

Pieces of the jigsaw puzzle:

 Similarities of minerals (sulpharsenides, chlorite, quartz, bismuth)  Underlying batholith/intrusives  Exaggerated geothermal gradient (Caledonian Orogeny + intrusion of ‘Lake’ batholith)  strong convection of meteoric and/or connate waters  Mineralisation emplaced as fault plane infill (both)

 Diverse structural settings: SC –Causey Pike Fault vs DHN –no thrust fault  Metasomatic aureole at SC [NOTE: No disseminated sulphides  S‐free magmatic fluids?]  First stage ‘early’ precipitation of silicates, oxides, and phosphates at DHN [S‐free (magmatic) fluids?]  Diverse host (and underlying) rocks: SC – epiclastic siltstone vs DHN – volcaniclastic, tuffs A story of magma and sediments THE STORY THEN:

Scar Crags: Thrust fault controls emplacement of intrusion (raised dome and/or stock‐like ridge) and it fluxes lots of S‐free magmatic fluids into the relatively porous siltstones (metasomatic aureole) Early stage:

Dale Head North: A near‐vertical fault plane acts as preferential pathway for magmatic fluids resurgence, leading to vein‐type mineralisation (S‐free, silicates, oxides, phosphates)

Scar Crags: A near‐vertical fault develops and become the preferential trap for magmatic fluids resurgence (focussing of flow) and ‘catchment’ of circulating connate/meteoric waters (these contains metals and Late stage: sulphur scavenged by surrounding rocks) = MIXED FLUID ORE Dale Head North: The near‐vertical fault remains the preferential trap for magmatic fluids resurgence (focussing of flow) but by now it also act as ‘catchment’ of circulating waters = MIXED FLUID ORE A story of magma and sediments: Early STAGE (t1)

Magmatic fluid mineralisation (S‐free) Magmatic fluid metasomatism (S‐free) A story of magma and sediments: Late STAGE (t2)

Mixed fluids mineralisation: Magmatic + Meteoric/Connate During late stage the convection of meteoric/formation water is much more developed Oddities: 1. Probably Ce‐Bastnaesite

BSE image

50 μm EDS spectrum Oddities: 2. Probably Xenotime

100 μm BSE images

20 μm EDS spectrum Thank you for your attention Questions?

My typical style is to finish with a ‘thing of beauty’ –This time: The Ferrari Monza SP2 FUTURE PROGRESSES (limited by funds availability):

‐ Thin sections of host rock (petrography, effects of ‘bleaching’) ‐ Whole rock X‐ray fluorescence: Non‐bleached vs. bleached siltstone ‐ O, H stable isotopes on quartz (possibly also chlorite) ‐ S stable isotopes on sulpharsenides ‐ Fluid inclusion study (quartz) ‐ LA‐ICP‐MS on fluid inclusions Sb elemental map –up to 5 wt% Alloclasite with a cobaltite inclusion