Blog

This blog will provide informal updates on the HiTech AlkCarb project, written by different researchers highlighting fieldwork, lab studies, conferences and Expert Council meetings. Keep track by following our Twitter account (@HiTech_AlkCarb) and sign up to our monthly newsletter.

Posts

HiTech AlkCarb Open Day and fieldtrip at Kaiserstuhl, October 2017

Children learning about the Earth at the Kaiserstuhl Open Day.
Ben Walter presenting an overview of the geology of the Kaiserstuhl at the end of the Open Day.
The centre of the town of Staufen showing damage to the Rathaus and nearby buildings from past drilling activities.
The HiTech AlkCarb team at the Teufelsgrund mine.
View from the Rasthaus Lenzenberg.
The HiTech AlkCarb team at the Orberg carbonatite quarry.

In October 2017, after nearly 20 months of work conducted at the Kaiserstuhl, the HiTech AlkCarb team decided it would be a good time to provide some feedback to the general public. Hence, on Sunday 8 October the HiTech AlkCarb project invited members of the public to an Open Day at the Naturzentrum Kaiserstuhl in Ihringen (http://www.naturzentrum-kaiserstuhl.de). It was planned to introduce the geological and geophysical findings of the work conducted at the Kaiserstuhl. The exhibits focused on the geophysical work, water sampling and geology. The public was introduced to the general uses of rare earth elements (REE) and what importance carbonatites have as hosts for REE deposits, and also to a wider understanding of geological processes. The day offered activities for children such as building your own 'earth' and finding hidden magnets, and opened with a live mini–volcano welcoming the attendees. The Open Day was advertised in the local municipality newspapers and in local newspapers. On the day some 150 people came to the Naturzentrum Kaiserstuhl to interact with the HiTech AlkCarb team. The day ended with a talk by Dr. Ben Walter, giving a detailed overview of the geology of the Kaiserstuhl, in the Rathaus conference hall.

Mr. Kai Kircheldorff from the Badische Zeitung interviewed Prof. Frances Wall and Dr. Ben Walter, and a very positive article was published in the newspaper on 10 October 2017 (http://www.badische-zeitung.de/ihringen/der-kaiserstuhl-ist-eine-beispielregion-fuer-seltene-gesteine--143196319.html).

The Open Day was followed by the Kaiserstuhl Natural Laboratory fieldtrip and workshop, which was organised by the team from Eberhard Karls University Tübingen and Terratec Geophysical Services. Some 20 participants of the HiTech AlkCarb team were present, together with four external invited experts. All participants met in the evening on Monday 09 October 2017 at the Kapuzinergarten Hotel in Breisach and the Kaiserstuhl Natural Laboratory fieldtrip was opened by an introduction by Prof. Dr. Gregor Markl.

At the beginning of day 1 the participants were shown the structural damage to the buildings at the town of Staufen, which has led to a generally negative public perception of borehole drilling in the area around the Kaiserstuhl. In Staufen seven boreholes were drilled to establish borehole heat exchangers (BHE). Unfortunately, at one of the boreholes water entered layers of anhydrite which reacted with water and became gypsum. This can lead to up to a 61% increase in volume of the layers. The damage caused by this process is visible in the Town hall and adjacent buildings in Staufen.

The first day focused on outcrops of mineralised veins along faults which separate the Triassic sedimentary rocks (part of the Rhinegraben Mesozoic sequence) from the gneissic and granitic Variscan basement rocks of the Black Forest inlier. This was followed by a visit to the Teufelsgrund mine (Münstertal), which is a typical representative of the vein related fluorite–barite–galena quartz–dominated veins formed by fluid mixing. The mine is nowadays open to the public. The day ended at the Almgaststaette Kälbelescheuer where presentations on carbonatites and alkaline rocks by invited experts Dr. Anton Chakhmouradian and Dr Stefano Salvi were followed by supper.

The second day started with an introduction of the geology of the Kaiserstuhl by Dr. Ben Walter. The field day was dedicated to the extrusive rocks of the Kaiserstuhl. We visited outcrops showing tephrites, phonolite satellite intrusions at the Kirchberg, tephritic ash layers, carbonatite lapilli and lava, as well as monchiquite and limburgites (olivine nephelinites and basanites). This was a perfect hot autumn day which ended at the Rasthaus Lenzenberg with the most stunning views over the Rhinegraben towards the South. After the HiTech AlkCarb management meeting, a superb buffet of local specialities fed the hungry participants.

The third and final day was dedicated to the intrusive rocks including the carbonatites of the Kaiserstuhl. The different rocks were seen while walking a 10 km traverse from the east to the west of the Kaiserstuhl centre. We were able to investigate the sheeted nature of the intrusions around the margins of the Kaiserstuhl carbonatite; understanding this contact zone is very important for development of the HiTech AlkCarb geomodels. Entertaining and lively discussion was order of the day with Anatoly Zaitsev, Anne McCafferty and Klaus Brauch ending the day with presentations. Excellent supper at our wonderful host Ingelbert Kai's establishment finished the tour in an admirable fashion.

A well organised fieldtrip, during which many fruitful discussions were held, ended on Friday morning when everybody departed to incorporate the new ideas and findings into their work.

Alex Speiser and Pete Siegfried


Second HiTech AlkCarb field visit to Mongolia, September 2017

HiTech AlkCarb team members Kate Moore and Kathryn Goodenough with invited experts Franco Pirajno, Guillaume Estrade, Martin Smith and Wei Chen, at Mushghai Khudag
The camp at Mushghai Khudag
HiTech AlkCarb team members Kate Moore and Kathryn Goodenough with invited experts Franco Pirajno, Guillaume Estrade, Martin Smith and Wei Chen, at Mushghai Khudag
The whole expedition team at the Mushghai Khudag camp
Banded pegmatite intrusions, Khan Bogd

The alkaline and carbonatite complexes in Mongolia are an extremely important natural laboratory for HiTech AlkCarb, and so the project team decided that a second trip to the country would be essential. This trip took place in September 2017, led by Jindrich Kynicky. Arrival of many team members was delayed due to storms in Amsterdam, but those that it made it on time were able to participate in a half–day workshop on the Mongolian alkaline complexes. The next morning, the whole team assembled in Ulaan Baatar, and we set off to the Gobi Desert in a convoy of eleven vehicles. Members of the HiTech AlkCarb project were joined by invited experts from Australia, the UK, France, China and Russia, as well as collaborators from German, Czech and Mongolian universities. The logistics of the trip were very ably organised by the Mongolian Society of Economic Geologists, who provided impressive transport and catering as well as organising accommodation.

The first day was spent driving south across the vast and empty Mongolian landscape, with only the occasional yurt or camel to enliven the view. After a night in a roadside hotel, we arrived at the Mushghai Khudag complex at lunchtime. This is an excellent example of the shallow levels of an alkaline–carbonatite complex, with trachytic lavas cut by shallow–level intrusions of rhyolite, trachyte, carbonatite, and apatite–magnetite rock, and associated fluoritite veins. It will provide crucial information for the shallow–level plumbing part of the geomodels to be developed by the project. Our logistics team set up a great field camp in the middle of the complex, and we were able to spend two days studying the geology. An extra highlight was the superb display of stars at night, with no light pollution around the camp.

From Mushghai Khudag we drove to the Southern Gobi Rift Zone, crossing mile after mile of open gravel plains before passing the Oyu Tolgoi copper–gold mine, one of the world's largest copper–gold deposits. That evening we settled in to a small hotel in Khan Bogd village, our home for the next few nights.

The Khan Bogd pluton is a huge peralkaline granite pluton, some 40 km across, and easily visible on satellite images of the Gobi Desert. It is very well exposed, with a landscape of granitic tors separated by gravelly hollows, standing above the surrounding desert. A distinctive feature of this pluton is the abundance of roof pendants of country rock, forming some of the higher hills. Around the margins of the pluton and the roof pendants, stunning pegmatitic intrusions can be seen in the granite. Many of these intrusions have a banded form, with alternating pegmatitic and aplitic layers. Rare zirconosilicate minerals such as elpidite and armstrongite are common, and at one locality we were lucky enough to find the very rare mongolite. Where the pegmatites intrude country rock, they have caused extensive metasomatism (fenitisation).

After three days on Khan Bogd, we drove back to Ulaan Baatar, where a final day was spent at the Museum of Geology in the Mongolian University of Science and Technology, packing up samples and preparing them for shipment. Our colleagues in Mongolia are now undertaking a lengthy permitting process, and we look forward to the arrival of the samples in the near future!

Kathryn Goodenough

Buddhist monastery on the Khan Bogd pluton
Hunting for mongolite in a sandstorm

HiTech AlkCarb fieldtrip to Greenland, June 2017

Iceberg in the fjord
Iceberg in the fjord
Gregor Markl for scale on magmatic layering in kakortokites, Ilímaussaq. Black layers are arfvedsonite-rich, red layers eudialyte-rich, and grey layers are alkali feldspar and nepheline-rich.

Representatives from the HiTech AlkCarb project and invited experts, Tom Andersen from the University of Oslo and Paul Boon from the University of Tübingen, visited the Gardar province in SW Greenland in June 2017 on a field trip organised by Sam Weatherley from GEUS. The theme of this fieldtrip was to review some classic examples of layering in magmatic systems with the aim of fuelling discussion on their formation mechanisms. Another aspect of the HTAC project is to understand the processes that occur in the roof zones of large intrusions, particularly in relation to the volatile activity, and the Gardar is an excellent place to study this. Renowned for spectacular geological exposure, agpaitic rocks (see Marks and Markl, 2017 for a review) and gorgeous eudialyte, the group was incredibly excited to (re)visit some of the world's most infamous rocks!

The trip commenced in Narsarssuaq where we joined the Kisaq, our vessel for the two weeks. Kisaq means anchor in Greenlandic – very reassuring for those of us without sea legs! The group sailed west to Grønnedal–Ika and travelled east over two weeks visiting both carbonatites and alkaline igneous intrusions.

First stop was the Grønnedal–Ika carbonatite–syenite Complex – here the group looked at one of the few carbonatites in the region and its relationship to the syenite. Adjacent to this is the Ivittuut peralkaline granite which was worked in the past for cryolite – historically used as a flux for processing bauxite for alumina. The group shared outcrops with an equally surprised cruise ship of tourists! In the Ikka Fjord the group sailed in a zodiac to see submarine tufa columns that form on alkaline springs by abiotic precipitation of the metastable, cold water marine ikaite (CaCO3.6H2O). The alkaline springs are sourced from meteoric water that have percolated through the Grønnedal–Ika complex. Once removed from cold water the mineral degrades to other carbonates over a period of hours.

Having admired some giant feldspar dykes en route, the group arrived at the infamous Ilímaussaq Complex. This multiphase alkaline to peralkaline intrusion displays some incredible magmatic layering, and is host to two of the most significant potential REE deposits in Greenland. To the north of the Tunalliarfik Fjord lies the Kvanefjeld (REE–U–Zn) deposit owned by Greenland Minerals and Energy Ltd., while the privately owned TANBREEZ Kringlerne REE deposit lies to the south.

The group travelled by helicopter to the Motzfeldt intrusion, which has a preserved roof zone – this was slightly cut short due to the weather closing in and a planned trip to see the inverted layering at Klokken the following day was unfortunately not possible.

The trip concluded with a day on the Qassiarsuk carbonatite that has both extrusive and intrusive facies preserved. This is a spectacular coastal exposure of lavas and a diatreme facies on the site where Eric the Red settled in Greenland.

Eimear Deady


Michael Marks and Gregor Markl admiring the distant Greenland Minerals and Energy deposit at Kvanefjeld, from the town of Narsaq.
An enormous clast from the carbonatite volcano exposed in the coastal section at Qassiarsuk.

Helicopter pick up from Motzfeldt.
The HTAC group and crew of the Kisaq in Narsarssuaq harbour before heading home.

HiTech AlkCarb work in the laboratory

HollyElliott

After the excitement of collecting your samples in the field, a lot of behind the scenes lab work is undertaken before you achieve publishable results. These results allow us to better understand the geological processes that occur within igneous complexes, and contribute to the developing HiTech AlkCarb geological models. The aim is for these models to be eventually utilised by exploration companies, to more efficiently pinpoint important deposits of critical metals such as the rare earth elements (REE) and niobium (Nb).

Amphibole fenite vein

The first step along this road is the obligatory radiation checks to see whether your samples are actually allowed in the labs, and the subsequent documenting (labelling, photos etc), before the samples can be submitted for preparation. The result of preparation can be a polished thin section, polished block, powder or whatever your analysis of choice requires.

Cathodoluminescence

My samples are fenites, which are metasomatised country rocks that have been altered by fluids expelled by cooling and crystallising carbonatite or alkaline–silicate intrusions. Once I have my thin sections made I undertake what I like to call 'recce work'. This involves investigating the mineralogical changes that the fluids have caused using petrological, cathodoluminescence and scanning electron microscopes. Petrological microscopy allows you to get a basic overview of the sample, but apart from determining (for example) that your feldspars are altered or that you have overprinting carbonate phases, you can only really determine your main mineral phases and textures using this method. These are very important observations and necessary for identifying areas of interest, but once you put the thin section under cathodoluminescence you see your sample in an entirely different light (pardon the pun). Using this method, different stages of fluid flow can be tracked, for example as zones in apatites or variations in carbonate colour. Fenitising fluids add ferric iron to the rocks, which can clearly be seen in the feldspars as a red colouration and is indicative that fenitisation has occurred. A scanning electron microscope can then be used as a quick and dirty method to determine the chemistry of individual mineral phases. This allows identification of unknown phases and also enrichments/depletions related to the fenitisation process. Images taken during all these processes are periodically posted on Twitter.

Scanning electron microscope

If the 'recce work' identifies any interesting trends or features these are then investigated further using a variety of different methods depending on the required outcome of the analysis. For example, fingerprinting fluid pulses may require zones in a sample to be analysed using a microprobe or laser ablation ICP–MS, whereas the identification of intergrown and similar mineral phases such as those in an amphibole/pyroxene vein may require XRD analysis. This is just scratching the surface of the techniques and methods available to geologists and chemists to allow us to investigate the effect of geological processes on our samples. Mapping the passage of fluids can be achieved using a technique called QEMSCAN, which essentially maps mineral phases and their chemistry; this can be useful to determine where REE minerals are within a sample. Isotope analysis of carbonates can determine their origin and indicate whether they have a 'true' carbonatite source or are the result of hydrothermal processes. For more information on these techniques please visit: http://emps.exeter.ac.uk/csm/facilities/

Data obtained by all these techniques are interpreted to identify trends that can be used in developing geological models. These not only further our academic understanding of igneous complexes and geological processes but also allow us to identify and understand the processes which cause enrichment of critical metals such as REE and Nb. In turn, these models are valuable tools for industrial partners allowing them to more efficiently pinpoint economic deposits. However there is a long road between the world of field work and sample collection, and the end result, that is rarely seen or understood.

Holly Elliott, September 2017


REE deposit road trip, Northern Gobi Rift Zone, Mongolia

Mongolia is a vast country, and one that is richly endowed in natural resources, including copper, coal, gold, uranium and rare–earths. The minerals sector accounted for 17.6% of the GDP in 20141. Most of this contribution is realised through exploitation of coal, copper, fluorspar, molybdenum, silver and cement. Although not currently exploited, there are according to the USGS, 9 known deposits of alkaline– and carbonatite–hosted REEs in Mongolia. Many of these complexes are concentrated in areas along the Northern Gobi Rift Zone (NGRZ) and the South Gobi Fold Belt (SGFB).

In September 2016 Jindřich Kynický led a group of HiTech AlkCarb partners and expert collaborators Dr. Wei Chen (Chinese University of Geosciences), Yondon Majigsuren and Prof. Enkhbat (Mongolian University of Science and technology) on an expedition to the NGRZ to study some of the carbonatite and alkaline complexes within this natural laboratory. Key targets for the group on this 10–day, 1500 km off–road adventure into the heart of the Gobi Desert included Khotgor, Bayan Koshu, Mushgai Khudag, Durbent Doritu and Chetzu Teeg. An important point for the HiTech AlkCarb project is that these complexes are exposed at various erosion levels that correlate with the uppermost portions of alkaline and carbonatite systems.

The expedition began by stocking our trucks with water, dried food, camping equipment, several kilos of banknotes, and then a 550 km journey from Ulanbataar to the NGRZ. The first geological stop was Khotgor, a syenitic and alkali granitic intrusive centre, complete with its own shaman shrine and ancient petroglyphs. It is the largest known REE deposit in Mongolia, enriched in both silica and heavy REEs. The complex has experienced Na metasomatism, which induced extensive remobilisation of REEs, and generated an extensive set of fluorite–carbonate veins.

The next complex, Bayan Khoshu, was eroded further into the alkaline system, revealing late Jurassic – early Cretaceous monazite and syenite plutons, together with trachytic dykes and lava flows. Friable, mica–rich fenites formed here adjacent to multiple stages of carbonatite intrusions. REE mineralization at Bayan Khoshu is hosted within monazite associated with a late stage silicification event.

Mushgai Khudag, the most extensive and best exposed of the complexes we visited, is the second largest REE deposit in Mongolia. There we examined altered nelsonite (apatite + magnetite) within the uppermost parts of the intrusive system, and heavily fluoritized and brecciated country rock. Previous exploration work has showed that the apatite and fluorite are the primary hosts of the REE mineralization, containing up to 17 wt. % REO.

Minimal levels of erosion at both Durbent Doritu and Chetzu Teeg reveal extrusive volcanic rocks. Lava, pyroclastic sequences and epiclastics such as large debris flows are well exposed in these locations. The underlying magma chamber at Durbent Doritu is very much a mystery, therefore it is hoped that geochemical analysis of xenoliths collected from the lava flows will determine whether any REE enrichment has occurred. At Chetzu Teeg the ring structure of this volcanic complex is still clearly visible, intruded into granites of Permian age, making this a good example of a young magmatic system exploiting the pathways created by older magmatic activity.

This exciting mixture of sites allowed us to investigate the alkaline systems at a variety of depths, helping us to visualize and understand their 3D characteristics and patterns of REE mineralization. Study of these complexes and samples collected will generate much data and theories that, in years 3 and 4 of the project, will feed into new geomodels for REE mineralizing systems in alkaline and carbonatite rocks.

The expedition was a brilliant adventure in addition to a spectacular insight in to the Mongolian magmatic systems, a truly epic experience. The team camped each night under the stars without any sources of water, therefore wet wipe showers were a must. Evenings were spent digging up and burning dung in camp fires, learning traditional Mongolian songs and discussing our ideas about the geological sites we visited during the day.

In addition to first class geology (many thanks to Jindřich), the memories of Mongolia will also be of adventure and the warm welcome and much appreciated logistical support of our Mongolian collaborators. A second team from HiTech AlkCarb will visit further alkaline and carbonatite complexes in September 2017 to collect additional field observations and samples that will be used to address key science questions and in the construction of the geomodels. We wish them luck on their adventure!


Holly Elliott and Sam Weatherley


1Xun, S. 2017. The Mineral Industries of Mongolia, In: 2014 Minerals Yearbook, Mongolia, USGS. Accessed 20/July/2017.


Fieldwork in the NW Scottish Highlands and Expert Council Three in Edinburgh

Participants (L to R) E. Deady, G. Gunn (both BGS) and H. Elliott (CSM) admiring fenite in the snow at Ledmore Marble Quarry.
All field trip participants at the UK's only carbonatite on the shore of Loch Urigill.

The fantastic scenery of the Scottish Highlands is undoubtedly the best place to observe the large–scale geological processes that shaped Britain during and after the Caledonian Orogeny (Cambrian to Devonian). Eleven intrepid HiTech AlkCarb members and three expert councillors (Gus Gunn, BGS; Ian Parsons, University of Edinburgh; and Anatoly Zaitsev, St Petersburg State University), set out from Edinburgh in April to visit key localities for Scottish alkaline intrusive rocks.

Hosted by Kathryn Goodenough, Eimear Deady and Gus Gunn of the British Geological Survey, the aim of this fieldtrip was to investigate the possibility that the Loch Borralan Complex could be used as a plutonic analogue for volcanism observed during Expert Council One, in the Italian Apennines. Braving horizontal snow and high winds, the group visited a classic Moine Thrust locality at Knockan Crag. Walking up through the stratigraphy, Kathryn delivered a tectonic overview allowing everyone to orient themselves in the geological setting. Following a teashop stop and narrowly missing a ferocious hail storm, the team headed to Ledmore marble quarry, where pseudoleucite syenite and nepheline syenite bodies (the so–called 'borolanite') intruded dolostone. The resulting metasomatic reactions and breccia bodies were spectacular! Many samples and one broken rucksack later, the team went in search of (and eventually found) Alan Woolley's fabled REE–enriched fenites within pseudoleucite syenites in a small waterfall described in his 1972 paper.

Well–rested and well–fed, the following day involved visiting the disused Allt a'Mhuilinn Quarry – the 'borolanite' type locality, before heading along a forestry track in search of 1980's excavations showing pyroxenite and nepheline syenite intruding quartzites. On the shores of Loch Urigill, the team visited the UK's only carbonatite, associated with the intrusion of the Loch Borralan pluton.

On route to the Loch Loyal Complex, the group engaged in some geo–tourism, visiting an Archaean layered mafic intrusion at Scourie More and the infamous Laxford Bridge road cutting. Arriving at Cnoc nan Cuilean on the shores of Loch Loyal, the team set to work finding the REE and Th enriched hydrothermal veins cutting syenites described by Hughes et al., 2013. Although the main exposure had collapsed into the waterfall, smaller veins and brilliant magma mingling textures were observed within the syenites and melasyenites.

Returning to Edinburgh, via the Edradour whiskey distillery, the fieldtrip gang were joined by consortium partners for a two–day Expert Council workshop at the Surgeons Hall. Experts in the fields of roof zone volatiles in carbonatites and alkaline rocks, in addition to sustainable mining were invited to present. Day one focused on roof zone volatiles, with overviews of current research being undertaken at two of our natural laboratories – Greenland, presented by postdoctoral researcher Will Hutchinson, and Kaiserstuhl, Germany delivered by postdoc Ben Walters. Our geophysical partner, Terratec Geoservices, delivered their latest update on the geophysical interpretation of surveys conducted at Kaiserstuhl during late 2016. The second day addressed the 'advancing sustainability' work package and saw several round table discussions. These pertained to the potential issues of mining carbonatites and alkaline complexes, and the information that can be provided by geologists to further sustainable development of potentially exploitable deposits.

Completing a fantastic week, a final bank holiday geologising day was spent at the well–exposed Elie Ness diatreme on the East Fife coastline. Here the remaining few sought the 'Elie Rubies', aka garnets within mantle xenoliths hosted in the diatreme fill.

Holly Elliott and Eimear Deady, May 2017

Airborne geophysical survey of the Kaiserstuhl complex and project presentation by  ”terratec

Talk of M. Tauchnitz (terratec) given at the DGG conference in Potsdam, Germany.
Interpreted model Resistivity section of Line_4 extracted from the 3D model.

The airborne magnetic and radiometric survey of the Kaiserstuhl Complex, one of the main natural labs for HiTech AlkCarb, has been completed by terratec geophysical services. 3600 line kilometres were flown and processing of the data is underway. Terratec would like to thank the team for the great work done and special thanks to Kai Naujokat from HTC Germany for flying this difficult survey.

In March 2017 Michael Tauchnitz (terratec) gave a talk with the title "Geophysical Investigation at the Central Carbonatite Complex Kaiserstuhl" at the German Geophysical Society (DGG) conference in Potsdam. The HiTech AlkCarb project, the test site of the central carbonatite complex in the Kaiserstuhl, the geophysical methods applied, and the preliminary results obtained were presented to the audience. The focus of the presentation was the joint data processing and 3D modelling/inversion of the high resolution near-surface and deep (approx. 300 m) Resistivity and Induced Polarization (IP) measurements. As a preliminary result, the interpreted model resistivity depth section of line_4 showing a good correlation to the known geology was shown and discussed.


Expert Council Two – Malawi – Fenite and Geophysics as Exploration Tools

View of the fenite breccia ring dyke from the central carbonatite at Tundulu.
Group photo of HiTech AlkCarb workshop attendees in gardens of Sunbird Kuchawe Hotel.
Monazite crystals (green) within dolomite carbonatite at Kangunkunde.
Small herd of elephants on the bank of the River Shire, Liwonde National Park.

The Chilwa Province, Malawi is famous for its early Cretaceous carbonatitic and alkaline volcanism in addition to excellent exposure of fenites (metasomatically altered rocks), providing a perfect destination for another HiTech AlkCarb Expert Council. Project partners from Mkango Resources Ltd, Alex Lemon and Will Dawes, teamed up with SoS RARE partner, Sam Broom–Fendley (Camborne School of Mines) to lead 50 expert geoscientists on fieldwork to six volcanic complexes. This was the largest geological research conference ever held in Malawi.

Lying at the southern end of the East African Rift, the Chilwa Alkaline Province displays a range of rocks including carbonatites, nepheline syenites and peralkaline granites in a Precambrian gneiss and granulite basement. The igneous complexes have been shallowly eroded, exposing intrusions and breccia above the magma chamber. Therefore the only way to understand deeper processes is to analyse surface exposures of intrusions and fenites or to use geophysical techniques.

After many attendees had journeyed over 48 hours, they showed their commitment listening to the first seminar session. Dr Alan Woolley, a world renowned carbonatite specialist, opened the talks introducing the geology of Malawi, followed by Sam Broom–Fendley acquainting us with Songwe Hill and Will Dawes (Mkango) providing an exploration company's perspective on Malawi prospects.

The first site was Songwe Hill, the flagship deposit of Mkango Resources, visiting trenches which revealed an outcrop of synchysite–rich carbonatite named 'the tip of the iceberg' by the Mkango team. Fenite breccias and late stage REE rich carbonatite intrusions were also viewed on site followed by a rare opportunity to view Songwe halved drill core.

Although evenings were filled with seminar sessions, one day was spent at the hotel for talks regarding the workshop subject – geophysics and fenites. Pete Siegfried opened talks by discussing how geophysical techniques play a role in the search for and understanding of alkaline complexes. After lunch, the fenite session convened with talks from specialists such as Sven Dahlgren, who has conducted significant research on Fen, Norway – the fenite type site.

Our break from fieldwork was followed by a visit to Kangankunde. Upon arrival geologists reverted to kids, hammering boulders of monazite–bearing carbonatite to find shiny green monazite crystals. That afternoon, the team were privileged to visit the core shed of Mota–Engil and spent happy hours inspecting Tundulu breccias and intrusions. The phosphate mine at Tundulu was visited the next day, where an Optichem employee showed the group where apatite rich carbonatites were mined for fertilizer.

After the last field day, visiting Nkalonje's fenite breccias and carbonatite intrusions, the workshop attendees dressed up in their glad rags to attend the gala dinner. Starting off formally with speeches from Prof Frances Wall, Alex Lemon and the Honourable Bright Msaka SC (Minister for Natural Resources, Energy and Mining), the night ended with dancing along to Malawian music celebrity Lucius Banda.

Whilst the majority of the workshop delegation flew home on day 8, a small hard–core group of geologists remained on for a 10 day fenite sampling mission. After a much needed afternoon off hippo, elephant and crocodile spotting on the Shire River, the team re-visited and sampled each complex. Data produced from the 190 kg collected, will be fed into a HiTech AlkCarb geomodel of alkaline and carbonatite systems. Read a longer account of the trip.

Holly Elliott, November 2016


Greenland fieldwork July–August 2016

The University of St Andrews team in the field, including Adrian Finch (left), Nicola Horsburgh (middle) and Will Hutchison (right).
Roof zone of the Ilimaussaq intrusion. The contact between the layers of country rock (predominantly black units, dipping to the right of the image) and alkaline intrusion (light grey) is visible in the centre left.

In July and August 2016 members of the HiTech AlkCarb project team (from the University of St Andrews) visited the Gardar Province in South Greenland. The Gardar is an ancient rift zone that was volcanically and tectonically active between 1300 and 1100 million years ago. Although the province is no longer active, it is of major interest to geologists because the subsequent uplift and glacial erosion have cut deep into the rift and exposed the rocks and magma chambers that once lay well below the surface.

Magma that stalled at upper crustal levels in the Gardar rift evolved to very extreme compositions. This generated high concentrations of incompatible elements, including uranium, thorium, niobium and tantalum, in the tops of these magma chambers. As a result the Gardar Province hosts some of the world's best mineralised magma bodies and our field work aimed to identify the roof zones of these alkaline complexes and understand more about the processes that concentrate the so–called 'rare–earth elements' (REE).

Our focus was the roof zones of the alkaline complexes Ilímaussaq and Motzfeldt. These complexes are only 50 km apart, host significant REE resources and yet their composition and magmatic evolution appears to be quite different. By comparing and contrasting these two unique complexes we wanted to understand whether or not the same underlying processes were taking place.

We were fortunate to have 5 weeks of glorious weather and this allowed spectacular views of the intrusions and detailed sampling surveys to be undertaken. We also had breathtaking views of the fjords, glaciers and mountain ranges of South Greenland. Intriguingly, despite the compositional differences between the Ilímaussaq and Motzfeldt complexes, we found that the magmatic processes taking place in the roof zones were very similar. In both cases we were able to identify sinuous alkaline dykes and sheets penetrating the country rock, and comparable chemical alteration textures were visible around the margins of each intrusion. We collected a range of geological samples and our next objective is to characterise rigorously their mineralogy and alteration using petrographic and microanalytical geochemical tools. We will develop a set of geochemical indicators for alkaline roof zones and use these new tools to evaluate other complexes in Europe (e.g., Kaiserstuhl, Germany) and understand whether or not these prospects might offer comparable REE resources to those in the Gardar.

HiTech AlkCarb – Expert Council One – Italy

June 15th saw the first expert council meeting of the HiTech AlkCarb team and associated expert council members. Attendees travelled from around the world to Italy to examine some examples of volcanic carbonatites and alkaline rocks, whilst being treated to Italian culture and food. The first expert council was convened to review the first five months work on the EU funded project and to focus on questions relating volcanic expressions of carbonatitic and alkaline rocks to the processes operating at depth.

Why Italy?

The group examining an outcrop at San Venanzo.

The Università degli Studi "G. d'Annunzio" Chieti–Pescara team are leading the research linking volcanic rocks to economic mineral–forming processes within the crust. The meeting aimed to bring the group together to see some examples of Italian carbonatites and alkaline rocks. We had two days in the field examining a phosphate–rich deposit that overlies a carbonatite, where a herd of cows seemed as interested in the rocks as we were. On day two of fieldwork we visited the volcanic complex at San Venanzo, and the diatremeic volcano at Polino. The fieldwork was complemented with plentiful, delicious Italian feasts and on the third day we arrived in Chieti ready for some serious discussions.

The village of Torrevecchia Teatina just outside the city of Chieti was the location for our presentation and discussion sessions. The morning session consisted of talks by team members on their research so far. The invited expert councilors (Marie Edmonds, Jock Harmer, Stefano Salvi, Tony Mariano Snr and Tony Marino Jnr) gave presentations on related aspects of the science or exploration as it currently stands. The afternoon was spent on 'sand–pit' discussions, which aimed to get us out of our comfort zones discussing a range of topics, with a range of different people from the group.

The fantastic trip was organized by Prof. Francesco Stoppa, Dr. Gianluigi Rosatelli and Dr. Andrea Tranquilli who brought together a mixture of geology, food and culture, leaving us all with very fond memories of Italy and stimulated to get back to the labs to continue our research.


The cows at Pianciano carbonatite and phosphate deposit. Photo courtesy of Alex Speiser.
Prof. Stoppa leads a discussion about the San Venanzo complex at a wall in the town which is built upon part of the pyroclastic material from one eruption.

Ground geophysics under way at Kaiserstuhl

Terratec have started the ground geophysical work at the Badberg location in the Kaiserstuhl, with two Electrical Resistivity Profiles looking down to approx.100 m. The data are very good quality, and promise well for the deeper investigations planned to start on the 25th of July. The terratec team was accompanied in the field by Björn Heincke from GEUS. As an outcome of this field work and the discussions we had, we will fine tune the future profiles and methodologies for ground geophysics. The airborne geophysical work is also under preparation.


Carrying out ground geophysics, Kaiserstuhl.
Carrying out ground geophysics, Kaiserstuhl.
Carrying out ground geophysics, Kaiserstuhl.


First meeting with the mayor of the Vogtsburg Gemeinde and heads of councils to introduce the anticipated scientific programme at the Kaiserstuhl alkaline-carbonatite volcano, Germany

View from Eichstetter viewing tower of the Badberg  (middle) and Haselschlachter Buck.

On 13 April 2016 the HiTech AlkCarb project team held a first meeting with the mayor and heads of local councils in Oberbergen at the Kaiserstuhl, Germany. During the meeting, partners of the project (from the University of Tübingen, terratec Geophysical Services GmbH & Co. KG, and A. Speiser Environmental Consultants) introduced the scientific programme and explained why we would like to work at the Kaiserstuhl.

The Kaiserstuhl alkaline-carbonatite volcano is an ideal project area in which to gain in-depth knowledge about how rare earth elements and other critical metals have become enriched in some volcanic rocks during the active volcanic phase. Over the past centuries plenty of scientific work has already been conducted, but now new and more advanced geophysical methods have been developed that will allow us to acquire more details during the project. This information will be used to meet the overall goal of developing new geo-models for international critical metal exploration programmes.

The initial fieldwork entails taking rock samples with a hammer from existing rock exposures and old quarries. Additionally, geophysical surveys will be conducted along tracks. The main focus of these activities will be at the centre of the Kaiserstuhl (Badberg and Ohrberg). This will be followed by an airborne survey during which magnetic and radiometric data will be collected using a helicopter. The area which will be investigated is approximately 12 x 12 km.

Finally, it is anticipated that a borehole will be drilled to obtain a continuous core of rock down to a depth of a few hundred metres. The final location can only be decided once the ground geophysical and airborne data have been analysed. The core will provide samples that we can analyse to study the enrichment of rare earth elements and other critical metals in the rocks at depth.

The mayor and heads of councils are very interested in this scientific research project. However, work can and will commence only once all necessary authorisation documents and permits have been obtained from the local government institutions. The mayor raised concerns following on from previous drilling in the area. Previously, in the village of Staufen, anhydrite layers started to expand after water leaked into that stratigraphic layer during and after drilling, resulting in damage to houses in the area. In Basel hydro-thermal drilling, where water was pumped into the borehole, resulted in some small earthquakes. We explained that the geology at the Kaiserstuhl is totally different to that in Staufen and Basel and that such issues should not occur at the Kaiserstuhl. Furthermore, we are only drilling to obtain a drill core and after further downhole measurements the hole will be sealed off. The University of Tübingen offered to provide a written statement stating that none of the above raised concerns will happen at the Kaiserstuhl. We mentioned that the only problem occurring during the drilling could be that we hit water. If so, we will take care of that and ensure that the borehole is sealed off correctly. Finally, the mayor asked us to provide him with proof of liability from the drilling company and with a long-term liability, which will be arranged by our project team.

To inform the wider public of the Kaiserstuhl area, the mayor suggested that we write a short notice for the local municipality newspaper in which we explain the project. This has been done and was placed in the edition of 22 April 2016.

Subsequently, the documents for the permit to conduct the initial geological fieldwork and geophysical surveys were submitted to the 'Landesbergdirektion' (relevant authority to grant such permits). On 27 April we received an answer that we can go ahead, as no permission needs to be granted in regard to the existing legislation, because the project is only for scientific work. Our geological research at the Kaiserstuhl will get underway in early summer 2016.

Alexandra Speiser 5 May 2016

HiTech AlkCarb kick–off meeting 22–23 Feb 2016 | Mission for Improved Mineral Exploration Underway!

The HiTech AlkCarb project kicked off in London, 22-23 February 2016, at the Natural History Museum. 29 participants attended the meeting, representing each of the 12 project partners. Special guest Michael Le Bas was also present, to guide and encourage improvements from his 1977 model, still considered the standard in understanding carbonatite complexes (see below).

Diagram of a carbonatite-alkaline rock complex (Le Bas 1977) based on observations in Kenya.

The project will:

  • Develop new geomodels to explore for 'hi-tech' raw associated with alkaline rocks and carbonatites, including exploration indicators to target mineralisation at depths to 1 km.
  • Improve and develop of geophysical and downhole exploration techniques.
  • Transfer into Europe expertise gained in African exploration.
  • Give Europe world-leading expertise in critical raw material exploration.

Day One was a project overview, with presentations from Frances Wall, the European Commission Officer, and work package leaders: Kathryn Goodenough (British Geological Survey), Pete Siegfried (Geo-Africa Prospecting Services), Klaus Brauch (Terratec Geophysical Services), and Alexandra Speiser (A. Speiser-Environmental Consultants). Plans for fieldwork this year in Greenland and Mongolia were discussed, as well as the first two Expert Council meetings, one in Italy in June 2016, and the second in Malawi in October.

The theme of Day Two was 'The Science' and started off with a review by Alan Woolley based on his series 'Alkaline Rocks and Carbonatites of the World', the most comprehensive catalogue available.

Presentations

Presentations and discussion then followed six key geological questions:

  • How can we predict what intrusive rocks are present at depth by using volcanic carbonatites and alkaline rocks exposed at the surface?
    Michael Marks and Gregor Markl
  • How can we relate mineralisation in shallow volcanic and sub-volcanic carbonatite and alkaline systems to predict richer deposits at depth?
    Gianluigi Rosatelli
  • How can we better understand the plumbing systems down to 1–2 km (the most important environment for mineralisation)?
    Jindŕich Kynický
  • Can we use the geochemistry and mineralogy of fenite (alteration around carbonatites and alkaline rocks) as an exploration indicator?
    Frances Wall and Holly Elliott
  • How can volatile elements in the roof zones of alkaline complexes (F, Cl, OH, S) be used to indicate if there is a prospective deposit below?
    Adrian Finch
  • Is the unusual element enrichment in scandium in carbonatites found at Glenover, RSA a potential economic resource?
    Pete Siegfried

The final presentation focused on the scientific research site in Germany. By acquiring new geophysical in combination with surface geological data, it will be the most detailed study ever of a carbonatite-alkaline complex.

HiTech AlkCarb kicks off at the Natural History Museum.

Dylan McFarlane 2 March 2016

@HiTech_AlkCarb