Gold Deposits of Suriname: Geological Context, Production and Economic Significance
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Netherlands Journal of Geosciences — Geologie en Mijnbouw |95 – 4 | 429–445 | 2016 doi:10.1017/njg.2016.40 Gold deposits of Suriname: geological context, production and economic significance Nicole M. E. Kioe-A-Sen1,2,∗, Manfred J. van Bergen2, Theo E. Wong1 & Salomon B. Kroonenberg3 1 Department of Geology and Mining, Anton de Kom University of Suriname, Paramaribo, Suriname 2 Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands 3 Delft University of Technology, Delft, The Netherlands ∗ Corresponding author. Email: [email protected] Manuscript received: 21 June 2016, accepted: 17 September 2016 Abstract Gold has been a major economic asset for Suriname for more than a century. The long history of gold mining, concentrated in large parts of a greenstone belt in the northeast of the country, began with small-scale artisanal extraction activities and has recently seen the development of major open-pit operations. Despite the range of mining activities, Suriname’s gold deposits and occurrences are under-explored from a scientific point of view. Primary gold mineralisations in the greenstone belt occur in multiple forms, and although their origin is commonly related to the Palaeoproterozoic Trans-Amazonian orogeny, the controls of ore formation in specific cases often remain obscure. This contribution presents an abridged overview of currently available information on the geological setting and characteristics for some of the main deposits where gold is extracted. In view of the consistent link between gold metallogeny and granitoid–greenstone belts in the northern Guiana Shield, the mineralised settings in Suriname are discussed in a regional context. Keywords: gold, mineral exploration, mining, Suriname Introduction which c.46% was produced by the Rosebel mine and the re- mainder by artisanal miners. Gold is currently one of the most important commodities for Despite the increasing gold production and interest in the Suriname. Starting from the 1800s this noble metal has always gold sector, there is still a lack of geological knowledge about had a significant impact on the country’s economy. Most of the the origin and evolution of deposits in Suriname, mainly due gold deposits are located in the NW–SE-stretching Marowijne to the inaccessibility of the tropical rainforest and the deeply Greenstone Belt in the eastern part of Suriname (Fig. 1). They weathered overburden. This paper presents a general overview formed during the Palaeoproterozoic Trans-Amazonian orogeny of currently available information on gold mineralisation in following the collision of the Archaean nuclei of the Guiana Suriname, and discusses recent developments in a regional ge- Shield and the West African Craton (2260–2080 Ma; Delor et al., ological context. 2003; Kroonenberg et al., 2016). The style of gold mineralisation has been classified as syn- to late orogenic (Voicu et al., 2001; Daoust et al., 2011). Currently, gold is being mined at various Gold exploration and mining in Suriname locations by small-scale operations as well as major companies. The Rosebel mine, the first large-scale open-pit mine in Suri- An extensive review of the history of gold exploration and name, has been in operation since 2000. In 2013, total annual mining in Suriname can be found in De Vletter & Hakstege gold production in Suriname was estimated at 807,500 oz, of (1998). The exploration for gold in the Guianas started at the C Netherlands Journal of Geosciences Foundation 2016 429 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.58, on 01 Oct 2021 at 22:14:31, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/njg.2016.40 Netherlands Journal of Geosciences — Geologie en Mijnbouw Fig. 1. Map of Suriname showing the main gold occurrences in the NE greenstone belt. end of the 17th century with the search for the mythical gold of industrial archaeology remain (Fig. 2). Subsequent small- region El Dorado along the imaginary Lake Parima. scale mining continued at a low level until serious interest in Suriname’s indigenous people had no knowledge of gold at exploration resumed in the 1970s through the activity of the that time, so early expeditions by the Dutch colonising powers Geological and Mining Service of Suriname. in 1687–1688 and 1720 were unsuccessful. In 1736, 0.5 kg of Since the beginning of the 1990s a new gold rush has de- gold dust was exported to the Netherlands, probably from the veloped, involving intensive, often illegal artisanal mining of Van den Bempdenberg along the Suriname River. Serious gold lateritic and alluvial deposits in many major creeks in the green- exploration started in the second half of the 19th century, and stone belt, as well as dredging in the Marowijne River and the the years 1874–1912 saw a real gold rush in the interior of Afobaka storage lake (Fig. 3). At the same time, the first large the country, of which now only heavily overgrown monuments open-pit gold mine was opened in the Gros-Rosebel savannah 430 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.58, on 01 Oct 2021 at 22:14:31, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/njg.2016.40 Netherlands Journal of Geosciences — Geologie en Mijnbouw Fig. 2. Steam kettle remaining from gold exploration in the early 20th century at Sara Creek (from De Vletter & Hakstege, 1998). Fig. 3. A scalian (gold dredge) in Afobaka hydropower lake (photograph courtesy of Ronny Asabina). area, c.80 km south of Paramaribo (Figs 4 and 5). It is oper- duction of 325,000 oz was noted at the end of 2014 (Iamgold ated by Rosebel Goldmines N.V., a subsidiary of the Canadian Corporation, 2014). The mine consists of eight separate pits. Iamgold company. Commercial production commenced in 2004. The US-based Newmont company is planning to open a second The total proven and probable reserves in 2014 were estimated large open pit by the end of 2016 in the Merian area north of at 8.6 million ounces at a grade of 1.3 g t−1, and an annual pro- the Nassau Mountains (Newmont Mining Corporation, 2014). 431 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.58, on 01 Oct 2021 at 22:14:31, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/njg.2016.40 Netherlands Journal of Geosciences — Geologie en Mijnbouw Fig. 4. Pay Caro pit in 2012 (photo: N. Kioe-A-Sen). A range of smaller foreign and domestic companies (e.g. years. The share of gold in total exports more than doubled Golden Star, Canarc, Wylap, NanaResources, Suparna Gold, in the first decade of this century. In 2014 its contribution Hunter Bay Minerals) have been active in exploring and ex- was 54.5%, significantly more than alum earth (16.5%) and oil ploiting gold mineralisations in many parts of inland Suriname (15.1%) (De Vletter et al., 1998; Centrale Bank van Suriname, since the 1990s. The small-scale gold operations are also con- 2014a,b). centrated in the greenstone belt. The intensity of activities fluctuates with the gold price. Seventy to eighty per cent of the artisanal miners are Brazilians (garimpeiros), and a minority Gold deposits in Suriname are mostly local maroons (Heemskerk, 2009). They usually mine placer deposits, and use a hydraulicing (sluice boxes) method In Suriname, the Guiana Shield comprises the 2.26–2.09 Ga (Figs 6 and 7) and mercury to recover the gold (Fig. 8). Marowijne Greenstone Belt and two 2.07–2.05 Ga high-grade N.V. Grassalco, a state-owned mining company, has an opera- metamorphic belts, the Bakhuis Granulite Belt and Coeroeni tion in the Maripaston area, Paradistrict, where tailings (bakas- Gneiss Belt, surrounded mainly by granite and gneiss bodies anti) from former small-scale operations are mined and pro- and felsic metavolcanics. A remnant of the sub-horizontal Ro- cessed, using mercury-free gravity concentration equipment raima Formation is located at Tafelberg in the centre of the (crushers, grinders, hydrocyclones and shaking tables) to re- basement area. Proterozoic and Early Jurassic dolerite dikes in- cover the gold (Figs 9 and 10). This modern operation started truded into the whole basement (Bosma et al., 1977, 1984;De production in 2014 (Grassalco, 2016). Vletter, 1984a,b; Kroonenberg et al., 2016) The current significance of gold for the economy of Suri- Gold mineralisation is essentially restricted to the name can be gauged from its contribution to the country’s Marowijne Greenstone Belt, which contains three main exports. More than 80–90% of exports come from the mineral metavolcanic–metasedimentary formations. The Paramaka For- sector, and the importance of gold has grown rapidly in recent mation consists mainly of ocean-floor metabasalts, locally with 432 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.58, on 01 Oct 2021 at 22:14:31, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/njg.2016.40 Netherlands Journal of Geosciences — Geologie en Mijnbouw Fig. 5. Mining at the Pay Caro Pit (photo: N. Kioe-A-Sen). pillow structures, and a series of island-arc meta-andesites to Secondary or placer accumulations occur as colluvial and al- metarhyolites and intercalated volcanogenic and chemical sed- luvial deposits from weathered material in terraces of recent iments. The Armina Formation is composed of a series of or abandoned rivers and streams (Dalhberg, 1984; De Vletter & metagreywackes and phyllites and minor conglomerates, de- Hakstege, 1998).