VOLUME 53

. JUNE 2018

Handover of groundwater boreholes to INSIDE: the

Handover of groundwater boreholes to the Beaufort West Municipality I 1 Mahlako Mathabatha

Ingress control activities in the East Rand goldfield of the Witwatersrand Basin I 3 Kefyalew Tegegn

The Superior Golden Loop I 5 Taufeeq Dhansay

Geoscientists receive doctorates I 7 Nontobeko Scheppers

Field transportation of geologists from the early 1900s up to 1930 I 7 Rehan Opperman Two boreholes with good-quality groundwater were handed over to the Beaufort West Municipality.

The Council for Geoscience and the purposes. With these quantities, Department of Mineral Resources this intervention by the Council for hosted a ceremony in Beaufort West on Geoscience and the Department of Tuesday, 13 February 2018 to hand over Mineral Resources will significantly two high-yielding groundwater boreholes contribute towards alleviating the water to the Beaufort West Municipality. crisis plaguing the Beaufort West area. The handover was initiated after the announcement by the former Minister A Memorandum of Understanding of Mineral Resources, Mr Mosebenzi was signed by representatives of the Zwane at the official opening of the Department of Mineral Resources/ Mining Indaba on 5 February 2018 Council for Geoscience and the Beaufort where he alluded to the good-quality West Municipality, followed by an groundwater that had been discovered official handover of the boreholes by by the Council for Geoscience in the the Director-General of the Department Province, particularly of Mineral Resources, Advocate Thabo in the Beaufort West area. Pump tests Mokoena, to the Mayor of the Beaufort on the two high-yielding boreholes West Municipality, Councillor Jeffrey van indicated a combined monthly supply der Linde alongside the Chairperson of of about 33 million litres of water, which the CGS Board, Dr Humphrey Mathe will sustainably cater for approximately and the Chief Executive Officer, Mr Mosa 44 938 people. Laboratory tests Mabuza. These boreholes were drilled indicated that the water is of good quality during a five-year geoenvironmental suitable for domestic and agricultural baseline study in the area in 2 I GeoClips

South Africa that is currently in progress. yielding scientific results in response to of the Council for Geoscience in its The main purpose of this study is to societal issues. research of the Beaufort West area. He identify possible environmental impacts furthermore applauded the team behind from anticipated shale gas exploration Councillor Jeffrey van der Linde this project for their excellent work. and exploitation. As part of groundwater conveyed his gratitude to the Council research and monitoring, the Council for for Geoscience for bringing water to the Geoscience drilled five boreholes to a Beaufort West community during the For more information contact: maximum depth of 169 m in the Beaufort period of drought. Dr Mathe thanked Mahlako Mathabatha West area. According to Minister Zwane, the Beaufort West Municipality for their Marketing and Communication this is a result of the multidisciplinary support and commitment during the +27 (0)12 841 1220 and integrated approach to geoscience period of exploration and urged the [email protected] mapping in the country, which is community to continue their support Geoclips - Volume 53 - June 2018 GeoClips I 3

Ingress control activities in the East Rand goldfield of the Witwatersrand Basin

Background A B

The ingress of surface water into underground mine workings has been identified as a significant hazard in the goldfields of the Witwatersrand. The cessation of operations at the gold mines of the Witwatersrand has led to the flooding of underground workings that may result in uncontrolled discharge of acid water from the underground C D workings to the surface, if not properly managed. As a result, pump stations and associated treatment plants have been developed to alleviate this problem. However, these solutions are costly to operate and, therefore, reducing the volume of ingress will reduce the long- term operating costs of these plants.

The Council for Geoscience initiated Surface conditions and monitoring of the surface conditions and ingress in the Modderbee crack. a study in 2002 to identify the ingress points into the Witwatersrand goldfields. Sealing of Modderbee crack To date, this study has attempted to quantify the amount of ingress for each point by applying different methods to measure direct inflow and outflow. 5 m

One of the main activities of the 2016/17 financial year in the ingress control task entailed assessing, checking and monitoring the current condition of previously identified ingress points. The task focussed mainly on the East Rand goldfield in view of updating or modifying recommendations that had been made by previous studies. However, given the probability that the surface conditions of the identified ingress points may have changed since these studies were carried out (owing to natural processes and anthropogenic Proposed design for sealing the Modderbee crack. activities such as the reworking of the mine dumps), it was deemed necessary about 1.5 m deep and plunges to the the Modderbee ingress area was dry to verify the existing ground conditions west where the ingress point is situated and there was no flow of water into the at these sites once more. at the margin. crack. By 13 February 2017, the surface opening had been filled to the level of Identification of the Modderbee crack The Modderbee crack ingress has been the surrounding wetland, suggesting that as an ingress point monitored on an annual basis to cover the rate of downward water flow is not at least one hydrological cycle. On sufficient to drain the water flowing into A new ingress point was identified south 4 April 2016, a small volume of water the crack. of Modder Road at the geographical was observed to be entering the crack. coordinates of latitude 26.17530°S and On 20 May 2016, using the bucket and Possible methods to stop the ingress of longitude 28.38437°E. The crack is stopwatch method, the flow of water was water into this crack were proposed and 25 m long, 5 m wide at the surface and measured at 6 L/s. On 5 August 2016, a working sketch was prepared. 4 I GeoClips

Sealing of the Modderbee crack (bidm 6) was placed below the HDPE The top 0.25 m of the excavated ground (construction) impermeable plastic followed by the top above the impermeable membrane was geomembrane (bidm 6) to cover the also covered by compacted sandy silty The road excavation indicated that the entire prepared surface over a width clay. The final step for sealing the crack overburden soil, with a thickness of of 12 m and a total length of 25 m, was to rehabilitate the site and to fix a more than 80 cm, consists of remnants including the area beyond the crack. hazard warning post. of slimes material left over from the removal of historical mine dumps. This material was cleared beyond the perimeter of the planned 12 m crack sealing surface. The first level of excavation to a width of 12 m around the crack continued to a depth of 0.40 m within the same slimes material. For the second level of excavation, the width was reduced to about 3.20 m, still keeping the crack at the centre, while excavation continued using manual labour to cover the next 0.50 m.

The third level of excavation was reduced to a width of 1.2 m around the crack, gradually reduced to 0.10 m up to the base of the crack. The first part Base of the crack exposed and ready for sealing. of this bottom excavation was within the contact layer of the top soil and A B C the underlying weathered quartzite that gradually hardens becoming very difficult to excavate manually. Finally, the crack, situated on hard quartzite rock continuing down to an unknown depth (at this stage), was prepared for sealing.

At this point, the field team identified an underground channel when they heard the sound of water flowing through the crack. Geophysical tests were conducted with additional investigation D E F methods being recommended to investigate the depth of the crack and the possible underground channel. It is proposed that four percussion boreholes be drilled to a maximum depth of 50 m when site conditions allow the team to access the site with the drilling machine.

Upon completion of the excavation work, sealing of the crack started from the bottom up to ground level by plugging the crack with cobbles and gravels. A 1.2 m x 0.6 m deep formwork was prepared over the entire length of the crack. A. Concrete filling. For more information contact: B. Completed concrete work. Concrete of 25 Mpa was poured into Kefyalew Tegegn the formwork and compacted to reduce C. Protective membrane (bidm 6). Engineering Geoscience and voids. The top of the concrete was D. Impermeable membrane (HDPE). Geohazards covered by a well-compacted silty clay +27 (0)12 841 1508 soil up to a level of 0.4 m to reach the E. Upper protective membrane (bidm 6). [email protected] ground surface. A bottom geomembrane F. Completed ground. Geoclips - Volume 53 - June 2018 GeoClips I 5

The Superior Golden Loop

Overview

The Council for Geoscience and the Geological Survey of Canada have an ongoing Memorandum of Understanding and Implementing Agreement. This agreement aims to promote the exchange of institutional knowledge and to explore possible areas of collaborative research between the two organisations. Collaboration officially began in October 2016 when the Council for Geoscience hosted several scientists from the Geological Survey of Canada for a workshop and field trip. The workshop covered various aspects of mineralising systems research being undertaken by the respective organisations and was followed by a geological field trip and tour of several mines in the Limpopo and Mpumalanga Provinces. (For more information refer to Geological map of Canada simplified according to lithological ages. The insert shows a map of the field trip Geoclips Volume 47 of December 2016.) with stars indicating various locations of interest.

The reciprocal part of this bilateral entered the Superior Province, which has of hydrothermal fluids that are typically rich agreement occurred in October 2017 several similarities to Archaean rocks of in remobilised precious metals such as when the Geological Survey of Canada the Kaapvaal Craton. The team also paid gold, silver, copper, lead and zinc. Several hosted several scientists from the Council a brief visit to the Appalachian Orogen, of these mineralised systems were visited for Geoscience. Similarly, this trip began which has a similar tectonic setting and throughout the Abitibi. with a workshop discussing various areas age to the Saldanian Belt. of research and a tour of the central office The field trip included a visit to the Sudbury of the Geological Survey of Canada in Superior Province region. This area is particularly noteworthy Ottawa, Ontario. The tour included a visit for the Sudbury Igneous Layered Intrusion, to the laboratories of the survey to view The ca 2750–2687 Ma Abitibi Greenstone which hosts significant nickel deposits. The the ID-TIMS (isotope dilution thermal Belt was the main focus area of the field trip emplacement of this large igneous complex ionisation mass spectrometer), SHRIMP across the Superior Province. The Abitibi is linked to a ca 1850 Ma extraterrestrial (sensitive high-resolution ionisation may be subdivided into several sections impact that formed an approximately microprobe) and simultaneous multi- based on its characteristic geochemical 200 km wide basin. After formation, this collector and quadrupole LA-ICPMS and geochronological signatures. The basin was rapidly filled by an impact- (laser ablation inductively coupled plasma rocks of the Abitibi consist of a lowermost related melt sheet. The large volume of mass spectrometer). These instruments succession of ultramafic to mafic volcanic the melt sheet provided a significant heat enable an exstensive range of analytical rocks often interlayered with felsic source enabling the development of a measurements and ultra-high-resolution volcanoclastic rocks. There is a gradual hydrothermal system and the remobilisation geochronological investigations. increase in the occurrence of sedimentary and concentration of nickel-rich melt. The derived siliciclastic rocks in the overlying extent of this impact event can be traced The workshop was followed by a field trip sequences, which are often capped by a for several hundred kilometres and is to some of the most famous geological thick layer of conglomerate. apparent with evidence of pseudotachylite and mineralised exposures of Canada. melt segregation and brecciation, and the Several notable similarities to South The Abitibi is surrounded and intruded by widespread development of shatter cones. Africa’s own geology were apparent and several plutonic bodies and intersected discussions ensued on the various types by an array of faults that run parallel to Grenville Province of research being undertaken on these the overall trend of the greenstone belt. geological terrains. The team visited Geochemical differences across major The regions surrounding the Superior deposits of the St Lawrence Platform, fault structures suggest that some of Province are defined by several high-grade which is similar in age to the Cape Basin, these probably represent ancient tectonic orogenic zones. One of the most prominent crossed the Grenville Province, which boundaries signifying accretionary orogenic zones crossed during the field trip has a similar tectonic setting and age to processes. The structures also provided was the Grenville Province. This province the Namaqua-Natal Belt, and eventually conduits for the transport and concentration forms a high-grade orogenic belt along 6 I GeoClips

A B C D

Stromatolite (A) and carbonate with brachiopod (B) of the St Lawrence Platform and migmatitic paragneiss of the Grenville Province (C and D).

A B C D

E F Various lithologies highly organic-rich sequences notable for around the Superior petroleum and natural gas resources. Province: A. Sudbury impact breccia with Future work pseudotachylite and overprinted by later The workshop and field trip in Canada glacial striations; B. concluded the first phase of the bilateral Impact shatter cones; agreement between the Council for C. Timiskaming Geoscience and the Geological Survey conglomerate; D. Porcupine turbidite; of Canada. Several themes were E. Tisdale sheared discussed, including the development pillow lavas; F. Kid and management of an accessible and Munro komatiite with a dynamic geodatabase and the importance spinifex texture. and applicability of an extensive analytical isotope laboratory. In addition, several the southwest boundary of the Superior peraluminous and rare earth element potential areas of joint research were Province, which formed during the mid– bearing plutonic rocks. defined with the aim of gaining a better late Proterozoic amalgamation of Rodinia understanding of the evolution and and comprised several fragments of older St Lawrence Platform mineralising systems operational during Archaean volcanosedimentary rocks. The the Archaean. Both institutions will now tectonometamorphic history of the Grenville Overlying the southern extent of the work towards realising the various defined highlights several periods of deformation Grenville Province and extending up to, themes in view of initiating applicable joint linked to progressive accretion. This and also overlying, the foreland of the research projects. began as early as ca 1710–1600 Ma, with Appalachian Mountains, is the St Lawrence peak metamorphism at ca 1080–980 Ma. Platform. The field trip briefly explored For more information contact: Postcollisional magmatism from ca 985– the St Lawrence units around Ottawa, Taufeeq Dhansay 955 Ma marked the end of accretion and Quebec City and on the flanks of the Mapping Geoscience the beginning of Rodinia breakup. The Grenville Province. These mostly comprise +27 (0)12 841 1075 postcollisional magmatism also includes Cambrian to late Ordovician carbonate [email protected] several phases of extensively mined and siliciclastic units, which also include Geoclips - Volume 53 - June 2018 GeoClips I 7

Geoscientists receive doctorates

The Council for Geoscience wishes to transformation of exploration/ congratulate two of its staff members, exploitation in the Earth’s Critical Zone Nigel Hicks and Taufeeq Dhansay, whose hard work has paid off, earning each of Dr Dhansay investigated how brittle them a doctoral degree. features in the upper crust control important Earth system processes The seismic stratigraphy, geological such as the concentration of energy evolution and CO2 storage potential of and natural resources (i.e. geothermal, the offshore Durban Basin, . gold and natural gas) and how dynamic kinematic modelling can be used to Dr Hicks undertook a basin-scale manipulate these brittle features for assessment of the Mesozoic basin fill sustainable exploration/exploitation. within the offshore Durban Basin on the east coast of South Africa. Carbon capture and storage (CCS) is a short- to medium-term climate change strategy designed to reduce CO2 emissions from large-scale emitters. South Africa, like many countries worldwide, is heavily reliant on fossil fuels for energy supply and is a significant contributor (in terms Dr Nigel Hicks received his PhD degree from the of per capita emissions) to CO2 emissions University of KwaZulu-Natal. on a worldwide scale. Storage of 2 anthropogenic (man-made) CO2 is a key entailed a basin-scale (10 000 km ) mitigation technique for the reduction of evaluation of the geology and structure Dr Taufeeq Dhansay (left) at the graduation ceremony global emissions. Successful storage of of the offshore Durban Basin in order to of the Nelson Mandela University in Port Elizabeth.

CO2 has been undertaken internationally identify, categorise and rank potential in a number of geological mediums storage media that may have the capacity For more information contact: such as depleted oil or gas reservoirs, to store carbon dioxide. Nontobeko Scheppers unmineable coal beds, deep saline Human Resources water saturated aquifers and basaltic On the evolution and mechanics of the +27 (0)12 841 1201 formations, in onshore and offshore brittle upper crust below South Africa: [email protected] environments. Dr Hicks’s PhD project Implications towards the sustainable

Field transportation of geologists from the early 1900s up to 1930

Browsing through some old photographs in donkeys rather than horses. In the Lowveld, used for killing snakes in and around the the archives of the Council for Geoscience this was likely due to the presence of the camp, hunting small game for fresh meat in Pretoria provides one with insight in what tsetse fly, with donkeys believed to be less and to protect the donkeys from animals the geologists of yesteryear had to endure susceptible to diseases caused by the of prey at night — a real threat in the early during their travels to do fieldwork. tsetse fly than horses. years of geological mapping!

In the early 1900s, the wagon was the main Wagons were mostly used to haul supplies The smaller buggy or spider carriages were means of transport (photograph A). Travel with a smaller spider or buggy wagon often used for activities of leisure as can be times were long and fieldwork trips often being used for general travel and leisure. seen in the photograph of people standing extended for up to six months or more. On some photographs it would seem in front of a baobab tree near Leydsdorp Roads and shops were sparse in large parts that wagons were sometimes used for (photograph C). An almost exact photo, but of rural South Africa and geologists often accommodation and as kitchens as well. with a person standing next to the baobab had to be self-sufficient for long periods in for scale, appears in Memoir 6 (1912) of between visits to shops. Water supplies In photograph B, camp was set up near the then Geological Survey. for human and animal consumption were what could have been a shop with a obtained from streams or fountains. During buggy carriage in the near distance. By the early 1920s, motorcars seemed to the early 1900s, geological mapping in For interest’s sake, what appears to be have been fully adopted by the Geological the former Transvaal mainly focussed on a double-barrelled shotgun (see insert) Survey. However, roads were often non- the Bushveld Complex and the Lowveld is visible to the left of the woman in the existent and wagon tracks were used as areas. The wagons were mostly drawn by photograph. The shotguns were probably roads in rural areas. Photograph D was A B taken on 30 January 1922 during the Shaler Memorial Expedition. The caption of the photo reads “Donkeys pulling motorcars over deep sands of the ”. It would seem donkeys were still ruling the roads in parts of South Africa. It must have been quite a mission showing South Africa to overseas visitors utilising dry riverbeds as roads! The dates in the photo album showed that the photos at and the Gamkaskloof were taken two days apart. It likely took most of C the day to travel the approximately 120 km between the two locations.

By the late 1920s, travelling by motorcar seemed much easier and photos taken by the well-known Dr A.L. Hall showed motorcars traversing rivers far and wide via ponts at places such as the Olifants River Pont — Sekukuniland (photograph E), and the Komati River near Swaziland.

D In photograph F, a person is shown riding a motorbike that had most likely been used as a means of private transportation by one of the Geological Survey geologists residing in Pretoria during a local field trip. The photo was taken from a locality approximately where the present- day Mayville in Pretoria is situated, facing northwards towards Wonderboompoort. It seems wicker-style sidecar bodies were E F very popular during the 1920s.

From here on the photographic record of motor vehicles used by the old Geological Survey is sketchy. Hopefully, more historical images will be found of the modes of transportation during fieldwork.

For more information contact: Rehan Opperman Economic Geology and A. Donkey-drawn wagon used for fieldwork. B. Wagon and buggy with double-barrelled shotgun shown in the Geochemistry +27 (0)12 841 1121 insert. C. Baobab tree near Leydsdorp. D. Donkeys pulling the motorcars over deep sands, Gamka River, [email protected] 1922. E. Crossing the Olifants River in 1929. F. Motorbike with wicker-style sidecar.

If you are not on our mailing list and you would like to receive a copy of GEOclips, please send an e-mail to: Mahlako Mathabatha, Marketing & Communication, [email protected] Private Bag X112, Pretoria 0001, South Africa / 280 Pretoria Street, Silverton, Pretoria 0184, South Africa Tel: +27 (0)12 841 1911 / Fax: +27 (0)12 841 1221 / www.geoscience.org.za