Abstract This volume is a collection of papers authored by senior managers and heads of Geological Survey organizations (GSOs) from around the world in an attempt to provide a benchmark on how GSOs are responding to national and international needs in a rapidly changing world. GSOs face an uncertain future and need to understand global trends. Whereas population trends are somewhat predictable, societal responses to change are much less so and technological change is fundamentally disruptive and chaotic. As countries adopt sustainable development principles and the public becomes increasingly (but not necessarily reliably) informed about environmental issues using social media, the integration of resource development and environmental stewardship becomes increasingly important. GSOs will continue to provide key information about Earth systems, natural hazards and climate change in this context. This introduction comprises a short review of the global trends affecting GSOs, a snapshot of the state of GSOs, examples of how GSOs are adapting their activities to the modern world, including the growing use of big data, and an examination of international collaboration between GSOs. The time is perhaps ripe to reinforce international collaborations through a global network of GSOs. To achieve this will require leadership and a focus on the big picture of global sustainability.

Abstract In the first decade of the 21 st century, surface exploration drilling around the Boliden Tara mine at Navan, Ireland, aimed at ~1-km-deep targets, was becoming ineffective. During 2010, the extensive geologic knowledge of the existing Navan orebody was leveraged in an Experts Meeting to promote near-mine discovery. Two ideas, of many, were of relevance to this paper: (1) undiscovered mineralized fault-related zones were predicted south of the orebody, and (2) seismic surveys could locate subsurface faults. By late 2012, seven 2D seismic lines (totaling 101 km) had been acquired, processed, and initially interpreted. Pre-stack time migration images were used for interpretation, augmented by diamond drill core data where available. The seismic imaging proved a “game changer” in terms of subsurface visualization and a priority target was identified 2 km south of the mine on the footwall crest of a large south-dipping basin-margin fault. The first hole intersected 34 m of mineralized rock with 14% Zn + Pb, but at greater depth than anticipated. Follow-up drilling was initially successful but proved to be challenging. The first hole intersected a deep structurally complex section of the newly discovered zone that required more drilling to establish its location and attitude. Further drilling, utilizing extensive navigational deflection technology, outlined a mineralized zone similar in nature to the Navan 5 Lens at depths of 1 to 2 km. Inferred resources through 2016 were estimated at 10.2 Mt grading 8.5% Zn and 1.8% Pb. Underground exploration development of this zone commenced in April 2017, and will allow accurate delineation of this significant discovery.

Abstract Sediment-hosted stratiform copper deposits comprise disseminated to veinlet Cu and Cu-Fe sulfides in sili-ciclastic or dolomitic sedimentary rocks. Sediment-hosted stratiform copper deposits are extremely common though economically significant deposits are rare. They account for approximately 23 percent of the worlds’ Cu production and known reserves in addition to being significant sources of Co and Ag. Three sedimentary basins (the Paleoproterozoic Kodaro-Udokan in Siberia, the Neoproterozoic Katangan in central Africa, and the Permian basin of central Europe) contain supergiant (>24 million metric tons (Mt) contained Cu) deposits. Sediment-hosted stratiform copper deposits are the products of evolving basin-scale fluid-flow systems that include source(s) of metal and S, source(s) of metal- and S-transporting fluids, the transport paths of these fluids, a thermal and/or hydraulic pump to collect and drive the fluids, and the chemical and physical processes which result in precipitation of the sulfides. Metal sources are undoubtedly red-bed sedimentary rocks containing Fe oxyhydroxides capable of weakly binding metals. Sulfur may be derived from marine or lacustrine evaporites, reduced seawater, or hydrogen sulfide-bearing petroleum. Metals appear to have been transported at low to moderate temperatures in moderately to highly saline aqueous fluids, with the temperature of the fluid largely dependent on the time of fluid migration in the basin’s burial history. These basinal fluids were focused to potential metal precipitation sites by thinning of the red-bed sequence at basin margins, by faults, by differentially permeable sedimentary units, by paleotopography within the basin, or along the margins of salt diapirs. Fluid movement produced widespread, basin-scale alteration that has commonly been overlooked but can form an important exploration guide. Sulfide precipitation occurred due to reduction, typically caused by reaction with carbonaceous rocks or petroleum. The amount of sulfides present at any deposit may be either metals or sulfide limited or could have been controlled by the amount of available reductant (e.g., petroleum). While understanding of sediment-hosted stratiform copper ore genesis at the deposit scale is relatively robust, there are still significant questions in regards its position in terms of basin evolution. A wide variety of basin architectures and processes can lead to the formation of sediment-hosted stratiform copper deposits. Despite general agreement that sulfides postdate sedimentation, the absolute age of mineralization in many deposits has been difficult to document and the available evidence suggests that deposits can form throughout a basin’s evolution from early diagenesis of ore host sediments to basin inversion and metamorphism. Supergiant and giant deposits formed in basins which underwent prolonged periods of fluid flow and in which unique conditions allowed for the accumulation of large amounts of metal-bearing fluid, sufficient reduced S, and large amounts of reductants.

Abstract The Zambian Copperbelt accounts for approximately 46 percent of the production and reserves of the Cen tral African Copperbelt, the largest and highest grade sediment-hosted stratiform copper province known on Earth. Deposits in the Zambian Copperbelt are hosted by the Neoproterozoic Katangan Supergroup, a rela tively thin (~5 km) basinal succession of predominantly marginal marine and terrestrial metasedimentary rocks that lacks significant volumes of igneous rocks. The stratigraphic architecture of the Katangan Supergroup in the Zambian Copperbelt is comparable to that of Phanerozoic rift systems. The basal portion of the sequence (Lower Roan Group) contains continental sandstones and conglomerates deposited in a series of restricted sub-basins controlled by extensional normal faults. These largely terrestrial sediments are abruptly overlain by a re gionally extensive, variably organic rich marginal marine siltstone/shale (Copperbelt Orebody Member, or “Ore Shale”) that contains the majority of ore deposits. This horizon is overlain by laterally extensive marine car bonates and finer grained clastic rocks that evolved through time into a platformal sequence of mixed carbon ate and clastic (Upper Roan Group) rocks with abundant evaporitic textures, including widespread breccias thought to record the former presence of salt, now dissolved. Rocks of the overlying Mwashia and Kundelungu groups are dominantly shallow marine in origin. Three significant tectonic events affected the basin. Extension associated with early rifting led to the devel opment of isolated fault-controlled basins and subsequent linkage of these basins along master faults at the time of Copperbelt Orebody Member deposition. A later period of extension occurred during late Mwashia to early Kundelungu time (~765–735 Ma) and is associated with limited mafic magmatism. Basin inversion and later compressive deformation (~595–490 Ma) culminated in upper greenschist-facies metamorphism (~530 Ma) in the Zambian Copperbelt. The majority of ore deposits in the Zambian Copperbelt occur within a 200-m stratigraphic interval centered on the rocks of the Copperbelt Orebody Member. Deposits are broadly stratiform and are grouped into argillite- (70% of ore) and arenite-hosted (30% of ore) types. The distribution, geometry , and size of deposits are fundamentally controlled by early subbasin fault architecture and the availability of both in situ and mobile reductants, the distribution of which is linked to basin structures. Argillite-hosted deposits occur within rela tively dark and locally carbonaceous siltstones and shales, suggesting the former presence of an in situ organic reductant. These deposits are laterally extensive with strike lengths up to 17 km. Arenite-hosted deposits occur in both the footwall and hanging wall of the Ore Shale and have maximum strike lengths of 5 km. They occur at sites that were geometrically favorable for mobile hydrocarbon or sour gas accumulation. Both argillite- and arenite-hosted deposits contain so-called barren gaps of weakly to unmineralized strata that are typically asso ciated with the fault-bounded shoulders of early subbasins. Two mineralization assemblages occur in the Zambian Copperbelt. The volumetrically dominant type con sists of prefolding disseminated and lesser vein-hosted Cu-Co sulfides. The most typical sulfide assemblage in the deposits is chalcopyrite-bornite with subsidiary chalcocite and pyrite. The Zambian Copperbelt is unusual among sediment-hosted stratiform copper districts in having abundant Co and low Ag, Zn, and Pb. The Cu-Co sulfide carrollite is widespread in the district, although cobalt is present in economic quantities in only some deposits on the western side of the district. The Zambian Copperbelt also contains ubiquitous, but volumetri cally minor, Cu-U-Mo-(Au) mineralization in postfolding veins. Cu-Co sulfides display complex textural relationships that are best explained by multistage ore formation. Diagenetic to late diagenetic mineralization is indicated by the typically nonfracture-controlled distribution of both sulfide and gangue phases, replacive textures of Cu-Co sulfides after diagenetic cements and pyrite, and an approximate 815 Ma Re-Os isochron age for sulfide precipitation at the Konkola deposit. Brines ca pable of mobilizing metals were most likely generated during development of evaporitic environments in units of the Upper Roan Group, and/or subsequent dissolution of these evaporites to form the Upper Roan Group breccias. Late diagenetic to early orogenic mineralization is recorded by prefolding bedding-parallel veinlets and tex turally and compositionally comparable disseminated Cu-Co sulfides. An Re-Os isochron age on Cu-Co sul fides from two arenite- and one argillite-hosted deposits of 576 ± 41 Ma is consistent with early orogenic hy drocarbon or sour gas production. The minor Cu-U-Mo-(Au) mineralization event occurred following postpeak metamorphism, at approximately 500 Ma. The Zambian Copperbelt ore province is characterized by stratigraphically and laterally widespread meta somatism that records a protracted history of basinal brine migration. Although the alteration history is com plex, it can be broadly categorized into an early Ca-Mg-SO 4 , anhydrite- and dolomite-dominant stage involv ing brine reflux below the level of Upper Roan Group evaporites; a second, K-dominant stage characterized by widespread and commonly intense development of K-feldspar and locally sericite, best developed in rocks of the Lower Roan Group and associated with ore; and a third, Na-dominant stage characterized by development of albite, commonly at the expense of earlier-formed K-feldspar. Albite dominates in Upper Roan Group brec cias and Mwashia-Lower Kundelungu strata. It is also locally associated with a late Cu-U-Mo-(Au) vein event. Although none of these alteration types are direct guides to ore, they demonstrate widespread brine circula tion within the lower parts of the Katangan Supergroup.