INSIDE: Shale gas developments in the Karoo Basin · 2020-05-26 · Maphuti Kwata Sustainable Resources and Environment +27 (0)12 841 1387 [email protected] The all new Young

VOLUME 47 . DECEMBER 2016

INSIDE:

Shale gas developments in the Karoo Basin I 1Doug Cole/Haajierah Mosavel

Characterisation of surface dust and trapped dust samples around some asbestos mine dumps in Mpumalanga Province, South Africa I 3Maphuti Kwata

The all new Young Geoscientists’ Network I 4Refilwe Shelembe

First South Africa–Canada Bilateral Collaboration Workshop I 5Refilwe Shelembe

New book on the Bushveld Complex I 7Maria Atanasova

Annual Conference 2017 I 8

Laboratory Services – new instrumentation I 8

Shale gas developments in the Karoo Basin

In 2015 and 2016, the Council for Geoscience undertook a collaborative project with the Karoo Research Initiative (KARIN) under the auspices of CIMERA (DST-NRF Centre of Excellence for Integrated Mineral and Energy Resource Analysis) with a view to investigating the shale gas potential and the properties and distribution of shallow and deep groundwater in the Karoo Basin.

Methane gas is known to occur in the Ecca Group shale of the Karoo Basin. The Whitehill Formation provides the best target for shale gas since it has similar total organic carbon contents to several gas-producing shales in the USA and maturity levels conducive to the production of dry gas.

The investigation focussed on core retrieved from two deep boreholes in the Tankwa Karoo (KZF-1) and the vicinity of Willowvale (KWV-1) in the Eastern Cape Province. Carbonaceous shale from the Ecca Group was sampled for desorbed gas in the field and sealed for

subsequent laboratory measurements of residual gas and Rock-Eval analysis. Shallow groundwater was sampled from wind pumps within a 10 km radius of borehole KZF-1 and from boreholes and rivers within a 10 km radius of borehole KWV-1. Artesian water emanating from depths of between 560 and 670 m in borehole KZF-1 was sampled, but no deep artesian water was encountered in borehole KWV-1.

Borehole KZF-1 which had been drilled to a total depth of 671 m intersected 657 m of Ecca Group shale overlying 14 m of Dwyka Group diamictite at the base of the borehole. No dolerite was encountered. Black carbonaceous shale of the Whitehill Formation was intersected at three intervals due to tectonic duplication caused by thrusting. Thicknesses from the top downwards were 19.5 m, 36.25 m and 2.45 m.

The desorbed gas measurements are very low for the Ecca Group shales, with the highest value being 0.047 m3 of gas

Core logging team at borehole site KWV-1 near Willowvale in the Eastern Cape (left to right): Cecil Tivani (UJ),

Claire Geel (UCT), Haajierah Mosavel and Doug Cole.

CGS 2016_ Geoclips - Vol 47_ December 2016_ 21-11-2016_ v1.indd 1 2016/11/30 01:39:17 PM

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Drilling rig and core boxes at the KWV-1 site near Willowvale.

Grey shale containing abundant lighter-coloured tuff beds of the Collingham Formation overlying black

carbonaceous shale of the Whitehill Formation at 420.46 m depth. A sample of the Whitehill Formation was

removed for gas analysis.

Shallow groundwater sampling from a borehole near Willowvale with Kate Robey, Doug Cole and Haajierah

Mosavel.

per tonne per day from the Whitehill Formation. Only the Whitehill Formation was sampled for residual gas, with the highest value recorded being 0.56 m3 of gas per tonne, with methane contributing 86 %. The results of the Rock-Eval analysis indicated that the shales are overmature and have a low potential for shale gas.

Borehole KWV-1 was drilled to a total depth of 2 353 m and intersected 410 m of dark-grey shale of the Fort Brown Formation, 13 m of black carbonaceous shale of the Whitehill Formation and 31 m of dark-grey shale of the Prince Albert Formation overlying 15 m of Dwyka Group diamictite at the base of the borehole. 1 245 m of sandstone, rhythmite and shale of the Ripon Formation occur between the Fort Brown and Whitehill Formations. Several dolerite sills up to 150 m intrude the entire Karoo succession. Gas contents are very low with no residual gas present. The highest total gas value recorded was only 0.2 m3 of gas per tonne, derived from a sample of carbonaceous shale from the Ripon Formation. The results of the Rock-Eval analysis indicated that the shales are overmature, probably as a result of deep burial and thermal metamorphism associated with dolerite intrusion.

The quality of the shallow groundwater around the KZF-1 borehole site was found to vary significantly, ranging from good-quality potable water to brackish water with elevated Na, Cl and HCO3 concentrations. The shallow groundwater and surface water in the vicinity of the KWV-1 borehole site was found to be of good quality, based on pH and electrical conductivity measurements. The deep artesian groundwater sampled from borehole KZF-1 consisted of good-quality groundwater emanating from brecciated Prince Albert Formation shale at 560 m depth and brecciated Dwyka Group diamictite at 671 m depth, interspersed with sulphurous groundwater from brecciated Prince Albert Formation pyrite-rich shale at 634.44–637.44 m depth.

The shale gas potential of the Ecca Group shales, including the Whitehill Formation in the two boreholes, was found to be minimal. The shales were found to be overmature owing


GeoClips I 3Geoclips - Volume 47 - December 2016

For more information contact:Doug Cole/Haajierah MosavelMapping Geology+27 (0)21 943 [email protected]@geoscience.org.za

Characterisation of surface dust and trapped dust samples around some asbestos mine dumps in Mpumalanga Province, South AfricaThe mining of asbestos in South Africa started in the 1800s and ceased in 2002 because of environmental and health reasons. Large operations of asbestos mining in South Africa took place in the Northern Cape, Limpopo and Mpumalanga Provinces. It is an environmental concern that numerous asbestos mine dumps situated in close proximity to human settlements in the Mpumalanga Province have remained unrehabilitated. Asbestos particles are microscopic in size and can be lifted from ground-based sources by wind erosion or during excavation processes. The purpose of this investigation is to characterise surface dust and trapped dust samples around human settlements that are close to ownerless and abandoned mine dumps. Thus, samples were collected from five sites, with three of these sites (A, B and C) situated close to Mbombela (previously named Nelspruit), the capital city of Mpumalanga Province. A fourth site, D, is close to Malelane on the eastern side of Mbombela near the Mozambique border gate, while Site E is located to the southwest of Mbombela.

The geochemistry results indicate the presence of oxides of Si, Ti, Al, Fe, Mn, Mg, Na, K, P and Cr metals which confirms the predominance of silicate minerals, as indicated by the following measurements: SiO2 (28.78 to 62.3 %), Fe2O3 (9.61 to 38.45 %) and MgO (14.94 to 41.2 %).

The dominant minerals measured were chlorite (Mg,Fe,Li)6AlSi3O10(OH)8,

to tectonometamorphic overprinting associated with the Cape Fold Belt in the case of KZF-1 and deep burial and thermal metamorphism from dolerite in the case of KWV-1.

This research is important, as it allowed for the sampling of in situ

deep groundwater for the first time. This will be a requirement for future regulations, should hydraulic fracking for shale gas proceed. Knowledge of the deep groundwater properties will facilitate empirical investigations into the possible contamination of the shallow groundwater.

Location of the sampling sites in the Mpumalanga Province.

Mineralogy data.

Calcite

Plagioclase

Quartz

Chlorite

Amphibole

Serpentine

Talc

Sampling points

m/m

%


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For more information contact:Maphuti Kwata Sustainable Resources and Environment+27 (0)12 841 1387 [email protected]

The all new Young Geoscientists’ Network The new committee of the Young Geoscientists’ Network (YGN) (formerly the Young Science Forum (YSF)), was elected early in 2016. This presented an ideal opportunity to re-establish and rebrand the network. A new logo was designed by the YGN executive committee and refined by graphic designer Jane Abraham to reflect the values of the network.

Geochemistry data for sites in the Mpumalanga Province.

Composition A B C D ESiO2 37.17 28.78 33.62 62.3 33.41

TiO2 0.21 0.4 0.05 0.59 0.02

Al2O3 4.87 5.32 1.96 13.4 1.39

Fe2O3 4.48 38.45 9.61 8.01 6

MnO 0.247 0.279 0.079 0.159 0.114

MgO 32.02 14.94 40.94 2.2 41.2

CaO 0.84 0.35 0.01 1.39 0.37

Na2O <0.01 <0.01 <0.01 1.08 <0.01

K2O 0.02 0.23 <0.01 0.74 <0.01

P2O5 0.046 0.144 0.02 0.176 0.014

Cr2O3 0.387 0.393 0.644 0.205 0.229

Total 99.64 99 99 99.9 100.2

quartz (SiO2), plagioclase (NaAlSi3O8) and serpentine (Mg3(OH)4(Si3O5). The other minerals detected in low concentrations were calcite (CaCO3) and talc ((Mg3[Si4O10](OH)2).

The shapes of the amphibole and serpentine minerals detected were granular, semitriangular and

semirectangular. The size particle range measured 70 µm to 100 µm for granular, 100 µm to 200 µm for semitriangular and 200 µm to 500 µm for semirectangular minerals.

The SEM-EDS data confirmed the presence of quartz (SiO2), serpentine (Mg3(OH)4(Si3O5)), amphibole (NaCa2

(Mg,Fe,Al)5(Al,Si)8O22(OH)2) and mica (KAI2(Si3AIO10)(OH)2. The non-silicate minerals were calcite (CaCO3), feldspar ((KAISQ3O8)-(CaAI2Si2O8)), dolomite (CaMg(CO3)2 and clinopyroxene ((Ca, Mg, Fe, AI)2(Si ,Al)2O6)).

The results confirm the predominance of silicate minerals in trapped and surface dust samples. The significant levels of amphibole and serpentine asbestos minerals measured suggest an increased risk of contamination to the nearby communities.

Scroll – The symbolic award of success in education and research (similar to obtaining a graduation certificate after hard work, commitment and determination)

Stars – Excellence applied in research

Y – Bonds and molecules of elements found in minerals

Wiggle in the G – Waves generated from a seismograph

Last segment of the N – Geological pick hammer

All these symbols indicate the inclusiveness of the YGN and pillars of excellence and hard work to which YGN members aspire. Anyone up to the age of 40 is welcome to join the network.

Old logo. New logo.



For more information contact:Refilwe ShelembeYGN Executive Committee +27 (0)12 841 [email protected]

MISSION

To create a strong network of active young geoscientists in the CGS and South Africa

VALUES

• Encourage development through participation in projects and programmes

The development and progression of education and innovation in the National Development Plan 2030 of South Africa are the pillars of the YGN vision, mission and values.

VISION

To help create sustainable professional development for young geoscientists at the CGS.

• Encourage excellence in participation in projects and programmes

• Invest in commitment and diligence• Uphold principles of continual

improvement

First South Africa–Canada Bilateral Collaboration WorkshopThe Council for Geoscience (CGS) hosted the first workshop on Mineralising Systems of South Africa and Canada from 17 to 28 October 2016. This was the result of the signing of a Memorandum of Understanding and the Implementing Agreement between the CGS and the Geological Survey of Canada (GSC). The main objective of these agreements is professional development through knowledge exchange, sharing and building. The themes of the workshop covered layered mafic intrusions, Bushveld-related granites, greenstone belts, structure-controlled gold mineralisation and characterisation, craton history and impact structures, to name a few.

The launch of the Mineralising Systems Workshop, which was inaugurated by the opening address of the COO, Dr Mosidi Makgae, mainly featured the rich geology of South Africa. A few presentations on similar Canadian themes were undertaken by the delegates from the GSC. The kick-off to the workshop presented the current projects and MTEF tasks of the CGS, such as the prospectivity of the Tugela Terrane, shale gas in South Africa, regional geochemical element distributions in the Bushveld Complex and rare earth elements in the Bushveld Complex. All presentations (except those concerning mines) were given by experts of the CGS and the GSC and these resulted in interesting and thought-provoking discussions. The seven-day excursion

of the workshop was characterised by early morning starts, late nights and winding roads in the Mpumalanga and Limpopo Provinces. The team left for the Nkomati Nickel Mine where the models of emplacement, crystallisation and other controlling factors of the Ni-Cu sulphide mineralisation of the Uitkomst Layered Intrusion are believed to be coeval and cogenetic with the Proterozoic Bushveld Complex. The excursion also included noteworthy discussions around the intrusive contact between the Transvaal rocks and the Rustenburg Layered Suite (RLS) and its contact metamorphic

aureole. The large and extensive Transvaal calc-silicate xenoliths in the RLS at type localities visited provided evidence of this type of contact. The typical extensive chromitite layers (Upper Group (UG) 1, UG 2, UG 3 and the Middle Group chromitites) visited at the Modikwa Platinum Mine and the Dwars River National Monument characterise the RLS and indicate the injection and mixing of new and old magmas. The Canadian Black Thor-Double Eagle Intrusive Complexes of the Ring of Fire are also classic examples of chromitite (and Ni-Cu-PGE) deposits. The workshop

Participants of the workshop prior to the commencement of the field excursion.


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group also visited the platinum reef which had been discovered by Hans Merensky in 1924. Today, the adit is still remarkably intact. The pegmatoidal pyroxenites and chromitite stringers found in the adit are good indicators of the position of the platinum reef. Although younger and a product of a meteorite impact event, the major lithologies of the Sudbury Igneous Complex in Canada are similar to those of the RLS.

Gold mineralisation observed at the Sheba Gold and Stibium Mopani Mines and in the Golden Quarry was discovered in the 1800s. These deposits are hosted in the classic Archaean Barberton and Murchison Greenstone Belts respectively and were controlled by brittle and ductile deformation. Pillow lava structures and spinifex textures in the komatiites are classic indicators of the volcanic setting in which the formations in the basal Onverwacht Group of the Barberton Greenstone Belt had been emplaced. The world-class Barberton Greenstone Belt, which is the largest of the fourteen greenstone belts in South Africa, and the Canadian Abitibi Greenstone Belt, are classic volcanosedimentary sequences which are remarkably similar.

Some of the interesting type localities visited during the excursion that also showcased the geology of South Africa included the Palabora Copper Mine which is the largest open-pit mine in South Africa, hosted by the Phalaborwa Carbonitite Complex (coeval with the Bushveld Complex), the giant stromatolites (stromatolites on steroids) in the dolomitic Malmani Subgroup of the Transvaal Supergroup along the Sudwala Pass and gold reefs in the Pilgrim’s Rest area in Mpumalanga. The visit to the renowned Vredefort Impact Structure, the oldest and second largest in the world, was the last trip of the workshop excursion. Deformation indicators such as shatter cones and pseudotachylitic breccias indicate the size and direction of the Vredefort impact event and how the rocks of the Witwatersrand Supergroup were overturned. The highlight of the workshop was an investigation into the historical development and the links between the Kaapvaal Craton in South

1. Group at open pit of Nkomati Nickel Mine; 2. In the abyss of the Golden Quarry; 3. Younging direction in

pillow structures along the Komati River; 4. Transvaal calc-silicate xenolith in the Rustenburg Layered Suite;

5. Giant stromatolites of the Malmani Subgroup along the Sudwala Pass in Mpumalanga; 6. Classic UG 1

chromitite layer in the Dwars River National Monument; 7. Studying borehole core in the Stibium Mopani Mine;

8. Pseudotachylitic breccias from the Vredefort Impact Structure.

Africa and the Superior Craton which forms the core of the Canadian Shield in North America. The dyke swarms on the Kaapvaal and Superior Cratons are evidence that these two (and a few others), which may have been rotated, were once fragments of a much larger stable platform.

The close of the workshop was marked by the identification of and agreement on common areas of collaborative research between the CGS and the GSC. The success of this Mineralising Systems Workshop marks the standing scientific relationship of these two surveys which will run from 2016 to 2020.

1



For more information contact:Refilwe Shelembe Mapping Geology+27 (0)12 841 [email protected]

The workshop organisers wish to thank everyone who contributed towards making this workshop a success. The workshop participants were R. Shelembe (organiser), R. Netshitungulwana (organiser), N. Baglow (organiser),

J.P. Hunt, M. Bensid, V. Mothetha, P. Bosch, T. Dhansay, G. de Kock, C. Hatton, J. Elsenbroek, L. Mutele, V. Nxumalo, S. Hlatshwayo, A. Billay, W. Bleeker, M. Houlé (GSC), P. Mercier-Langevin (GSC) and C. Lawley (GSC).

New book on the Bushveld Complex Microminerals of the Bushveld Complex South Africa

by

Maria Atanasova1, Bruce Cairncross2 and Wolfgang Windisch3

1Council for Geoscience, Pretoria; 2Department of Geology, University of Johannesburg; 3932 Crots Street, Pretoria

Microminerals of the Bushveld Complex South Africa

Maria T. Atanasova Bruce Cairncross

Wolfgang R. Windisch

The Bushveld Complex is world famous for its spectacular geology and platinum-chromium deposits. It covers an area of approximately 65 000 km2 and is therefore the largest layered complex in the world. It is equally well known for its esoteric platinum-group mineralogy. Apart from these commodities the Bushveld Complex is a source of secondary mineralisation. The main objective of this book is to document and publish the occurrence of these secondary minerals that occur as microminerals.

For several years, Maria Atanasova and Wolf Windisch have been collaborating in identifying some of the more unusual and interesting minerals from several Bushveld localities. Bruce Cairncross is well known for his mineral work and co-authored and edited the book.

Valuable SEM data and SEM images have been generated in this process and stockpiled for future use. The methodology followed has been that of traditional mineralogical research: Positive and quantitative identification of minerals using SEM and XRD; fieldwork to document the settings of the mineralised sites; the utilisation of geological and soil geochemical databases to compile locality maps using GIS software, and literature surveys to establish a database of previous work and gaps in the literature that should be focussed on.

THE BOOKThe book is in full colour, illustrating the magnificent beauty of the microscopic world of minerals that the Bushveld

Complex has to offer. Another important aspect of this work is that the documentation and publishing of these microminerals give an insight into the diversified mineralogy of the Bushveld Complex other than the well-known platinum and chrome deposits.

Target group readers include researchers of the Bushveld Complex and mines in the region, micromount specialists, local and international persons interested in the Bushveld Complex and members of the public who would be attracted by the beauty of these tiny crystals. This book will be a valuable addition to the library of any academic or researcher working in Bushveld type layered complexes worldwide. The book is illustrated profusely with colour photographs and SEM micrographs of microminerals, locality photographs, geological and

soil geochemical maps and historical photographs and maps.

For more information contact:

Thelma SwartCouncil for Geoscience+27 (0)12 841 [email protected]

Council for Geoscience+27 (0)12 841 [email protected] http://www.geoscience.org.za280 Pretoria Street, Silverton, Pretoria, 0184

LIMITED PRINT RUN!

437 PAGES

OVER 1 000 FIGURES

PHOTOGRAPHS

SEM IMAGES

35 SPECIES FIRST IDENTIFIED FOR SOUTH AFRICA

DETAILED REFERENCE LIST

GLOSSARY


If you are not on our mailing list and you would like to receive a copy of GEOclips, please send an e-mail to:Mahlatse Mononela, Go to Market, [email protected]

Private Bag X112, Pretoria 0001, South Africa / 280 Pretoria Street, Silverton, PretoriaTel: +27 (0)12 841 1911 / Fax: +27 (0)12 841 1221 / www.geoscience.org.za

“GEOSCIENCE FOR A CHANGING WORLD” A TWO-DAY MINI

CONFERENCE PRESENTED BY THECOUNCIL FOR GEOSCIENCE, PRETORIA

FROM 2–3 MARCH 2017

The CGS conference will bring together national and international

scientists under one roof to discuss matters of geoscientific interest.

Within the broad geological mandate of the Council for Geoscience,

special emphasis will be placed on prospectivity mapping, marine geological

mapping, seismic microzonation, modern methods in geological mapping and

aquifer recharge. Internationally renowned experts will participate as keynote

presenters and scientists from the Council for Geoscience will present research

undertaken for various national programmes. With this annual conference, the Council

for Geoscience hopes to provide its stakeholders with insight into all the nationally funded

research programmes it has been tasked to undertake. Four pre-conference workshops will

also be held dealing with prospectivity mapping, marine geological mapping and seabed mineral

exploration, the seismic microzonation of Johannesburg and global events in the South African

stratigraphic record.

Follow the website for new developments: http://geoscience.org.za/cgs/

Annu

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Conf

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Laboratory ServicesThe Petrography Section is proud to announce the addition of a new Olympus Petrographic Microscope fitted with a 5 megapixel camera to its inventory of instrumentation. This means that we are now able to add good-quality photomicrographs to our petrographic reports. Depending on the client’s publication requirements, the photomicrographs are available in TIF or JPEG formats. In addition, the Petrography Section offers concise and detailed petrographic descriptions. These descriptions include macroscopic descriptions of the specimen, the rock type, the mineral phases present, abundances and textural relations. Detailed petrographic descriptions take this further by adding X-Ray Diffraction (XRD) results, the interpretation of these results in relation to petrographic findings and high-resolution photomicrographs depicting the sample as seen under the microscope.

For more information contact: [email protected]


INSIDE: Shale gas developments in the Karoo Basin · 2020-05-26 · Maphuti Kwata Sustainable Resources and Environment +27 (0)12 841 1387 [email protected] The all new Young

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