This special issue of the Netherlands Journal of Geosciences / Geologie en Mijnbouw contains the proceedings of the Conference on the Economic Geology of Suriname, held on 16 January 2015 in The Hague, the Netherlands, to honour Dr Eddie Jharap (Fig. 1), founder and former Chief Executive Officer of Staatsolie, Suriname. At this conference the President of the Royal Netherlands Geological and Mining Society (KNGMG), Drs Lucia van Geuns, awarded him the prestigious Van Waterschoot van der Gracht Medal, the highest honour available to an earth scientist in the Netherlands. Dr Jharap expressed his gratitude in a warm and humble speech which highlighted both his strong personal motivation to contribute to the development of Suriname, and his astonishing accomplishments since the 1980s in founding and developing Staatsolie.

Staatsolie Maatschappij Suriname N.V., together with the gold mining industry, has gradually become a major contributor to the Surinamese economy since the decline of the alumina industry. In the last 35 years, about 110MMbbls (million barrels) of crude oil have been produced. Staatsolie is now in the early stages of fulfilling its VISION 2030, which is not only aimed at increased exploration and production but also at power generation, further diversification and regional expansion. The basis for achieving these goals is accelerated on- and offshore exploration, followed by growth in production. The offshore region remains a frontier area, with only a few wells drilled. Current production is about 17,000bopd (barrels of oil per day). Between 2007 and 2014, Staatsolie has spent about US$120 million on exploration. An integrated study for the Suriname–Guyana Basin carried out by Staatsolie in 2009 demonstrated the upside potential of this basin from a source rock potential perspective, which has been proven by both the Liza-1 oil discovery offshore of Guyana in 2015 and the Zaedyus-1 oil discovery offshore of French Guiana in 2011.

Staatsolie is now focusing its efforts on the near-shore area, where it recently concluded a five-well drilling programme, following a 3-D seismic survey. In the deep offshore area, international oil companies (IOCs) are actively pursuing the next discovery in the Atlantic Margin, partly driven by the conjugate-margin theory geologically linking South America and West Africa.

Staatsolie is also attempting to increase recovery from the most mature and largest oilfield, the Tambaredjo Field, through Enhanced Oil Recovery (EOR) technologies of which polymer flooding is deemed the most suitable, with estimated potential incremental recovery of up to 12%.

Staatsolie recognises the role of a highly skilled and motivated workforce and therefore continues investing in its people through internal as well as external training. Thirty-five years after it was founded by Mr Eddy Jharap, a geologist by training and the first Managing Director of the company, it can be stated that Staatsolie has taken its place in Surinamese society as a significant contributor to the economy, a preferred employer, a nucleus for industrial spin-off and an example for other companies.

The Suriname–Guyana and Ghana–Ivorian Basins exhibit strong geological similarities which are of interest from a petroleum exploration point of view. These include (1) a well-developed system of Late Cretaceous erosional canyons allowing coarse-grained shallow-water clastics to enter the deep marine basin to form attractive turbidite exploration targets; (2) a broad shelf with strong longshore currents which sort and transport coarse clastics into the canyon heads; (3) an organic-rich Cenomanian–Turonian hydrocarbon source rock which is thermally mature in the centre of the basin; and (4) a series of extensional fault-networks along the shelf margin that extend upwards from the Rift Sequence into the overlying Drift Sequence and which, along with the canyon geometries, enable migrating oil and gas to accumulate in combination structural and stratigraphic traps. In June 2007, Tullow and its partners made an important discovery in offshore Ghana, at Mahogany, which subsequently became the giant Jubilee field. Tullow is currently applying the same geoscientific technologies in offshore Suriname in the search for analogous subtle combination traps.

Bauxite, the raw material of aluminum, has been one of the economically vital natural resources for Suriname. Mining operations started about a century ago, and subsequent development of a refinery industry and hydro-electric power made Suriname one of the foremost bauxite and alumina producers worldwide for a long period of time. This paper presents a concise survey of the main geological attributes of its bauxite deposits and examines significant aspects in the development of mining in the country where alumina dominated the export revenues until a decade ago. The lateritic bauxite deposits are spread across the northern part of the country and developed on various parent rocks during Late Cretaceous–Early Tertiary times. Bauxites in the coastal lowlands formed on Cenozoic sedimentary deposits, whereas plateau bauxites originated on various crystalline rocks in inland regions of the Precambrian Guiana Shield. The composition of parent rocks and timing of bauxitisation point to a genetic correspondence with West African bauxites and a strong control of paleoclimatic conditions on the distribution and properties of bauxite in both regions. The more accessible bauxite deposits in the coastal lowlands are almost mined out, whereas the plateau bauxites have been extensively explored but have not been brought into production to date. For economic and environmental reasons, the future of the bauxite industry in Suriname is currently uncertain.

Humans have played an important role in fluvial systems because of the impact of their land-use activities, frequently leading to degradation of environmental conditions. Rivers, which are the primary agents in sediment transport, have thus been subject to changes in sediment fluxes. The Suriname River has been affected by anthropogenic activities since colonial times, and has experienced strong discharge and sediment-load changes since the construction of the Afobaka Dam in 1964. The river's estuary sediments largely consist of fine-grained sediments, originating, ultimately, from the Amazon River and transported by the strong tidal current. The influence of this tidal current is diminished at the head of the estuary, allowing the river flow to become dominant. Also remarkable is the interaction of the Suriname River and the westward-migrating mudbanks which is evident in the changing magnitude and volume of Braamspunt, a mudcape located at the mouth of the estuary. The regulated discharge of the river results in a change of the river's morphology, resulting, among other things, in the growth of river bars.

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.

This article investigates the origin of a rare occurrence of kyanite quartzites in the Palaeoproterozoic greenstone belt of Suriname. The rocks form elongated hills in the Bosland area, Brokopondo district, where they are associated with meta-sedimentary, meta-volcanic and granitic lithologies. Their mineral content and unusual Si- and Al-rich chemical composition are inferred to be the result of advanced argillic alteration of felsic volcanic tuffs and a later overprint by regional metamorphism up to lower amphibolite facies during the Trans-Amazonian orogeny. Structurally, the Bosland area seems centred within a contractional strike-slip duplex of a major dextral fault system. The alteration was probably associated with a high-sulphidation environment and involved significant to almost complete removal of alkali and alkaline earth elements. Pseudosection modelling and textures suggest that the precipitation–temperature (P–T) history of the kyanite quartzites started with shallow (<2kbar) hydrothermal alteration of the acidic tuffaceous volcanics, possibly in the andalusite stability field (T>350°C), and ended in peak metamorphic conditions in the kyanite–staurolite stability field (P>4kbar and T=500–650°C). Alteration events that preceded the peak of Trans-Amazonian metamorphism may be more common in the rock record of Suriname's greenstone belt, which lends support to the hypothesis that gold mineralisations in the region can be pre-orogenic.

The sedimentological, metamorphic, petrographic and geochemical characteristics of the Armina Formation, part of the Paleoproterozoic Greenstone Belt of Suriname in South America, are described, based on field, geochemical and petrographic evidence obtained through fieldwork along the Marowijne River and study of diamond drill cores from Rosebel Gold Mine (RGM). The metagreywackes show characteristic features of deposition by turbidity currents: coarse-grained, poorly sorted graded greywackes, covered by fine-grained, parallel-laminated phyllitic beds, often with convolute structures and climbing ripples. Their immature character and composition suggest deposition in an arc-trench environment. In the Marowijne River three different facies of metagreywackes are distinguished: (1) the greyish Bonnidoro Falls facies, characterised by common red millimetre-sized pseudomorphs after siderite in the finer beds, (2) the green Paroe Tabiki metagreywacke facies, with decimetre-sized calcsilicate nodules, both metamorphosed in the lower greenschist facies with chlorite as the main mafic mineral, and (3) the grey Armina Falls metagreywacke facies, geochemically similar to the Bonnidoro type but of higher metamorphic grade with biotite as the main mafic mineral. The metagreywackes from the Marowijne River show a predominance of quartz, plagioclase and lithic (tonalitic) clasts, suggesting exhumation of tonalite–trondhjemite–granodiorite plutons before deposition of the turbidites. There is a slight increase in maturity from (1) to (3), suggesting increasing weathering in the source areas. The metagreywackes of the RGM (JZone) have a predominantly metavolcanic origin, suggesting that they have a different provenance area than the Marowijne metagreywackes. Geochemically the spread in composition within each facies is larger than between the facies because of the wide range in grain sizes in each turbidite sequence. A large part of the rocks from the RGM, classified by previous authors as arenites, are geochemically and petrographically metagreywackes. Only a few RGM samples are real arenites, and plot as a separate cluster in geochemical factor score plots because of their low Fe and Na contents.

The Proterozoic basement of Suriname consists of a greenstone–tonalite–trondhjemite–granodiorite belt in the northeast of the country, two high-grade belts in the northwest and southwest, respectively, and a large granitoid–felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U–Pb and Pb–Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2–1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.