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The productivity of milling circuits is sensitive to the size of mill feed. Uncertainty about the size of caved ore presents unique challenges to forecasting and controlling mill throughput rates. Part I of this paper showed how fragmentation size and hang-up frequency relate to geology, proximity of drawpoints to the cave boundary and the height of draw at the New Afton mine. The second part, presented here, investigates the impact of varying caved fragment size on mill performance. Analysis of historical mine and mill data showed that mill feed size and subsequently mill throughput are sensitive to the areas being mucked within the cave. Fragmentation measurements of drawpoint muck, comminution tests and calibrated mill models were used to assess the impact of variations in feed size and hardness on New Afton mill performance. Image-based size analyses of drawpoint muck and comminution tests showed that coarser material generally contained harder rock. [ABSTRACT FROM AUTHOR]

This paper relates developments in the science of geology to forms of governmental rationality in Canada during the late nineteenth century. By so doing it opens for discussion a topic rarely broached by political theorists: the role that the earth sciences played in the historical evolution of forms of political rationality. The paper contests theoretical approaches that understand the relation between scientific knowledge and state rationality as only instrumental. Instead, the paper demonstrates how attending to the temporality of science (as evident in the emergence of specifically geological ways of seeing nature during the period) helps us understand the ways in which science is constitutive of political rationality, rather than merely its instrument. This argument is developed through a critique of Michel Foucault’s concept of ‘governmentality’, a concept that historicizes political rationality, yet remains silent on how the physical sciences contributed to its varied forms. The paper concludes with reflections on the implications of such an argument for theories of the social production of nature. [ABSTRACT FROM AUTHOR]

In this paper, we briefly describe the Argus spectrometer and its mission. We then focus on the process to determine the geolocation of the spectrometer's flight data. For the Canadian Advanced Nanospace eXperiment 2 (CanX-2) Argus flight, we have used Simplified General Perturbations 4 (SGP4) propagation for position determination. Two sets of flight data are presented as examples. We estimate the uncertainty in the geolocation of Argus data using this method and investigate potential improvements for future Argus flights. [ABSTRACT FROM AUTHOR]

Abstract: The Archean western Superior Province in Canada represents the nucleus of the North American continent whose origin has been speculated to be the result of widespread crustal accretion some 2.7Ga ago. In this paper, crustal and upper-mantle seismic discontinuities beneath the western Superior Province of the Canadian shield are imaged with teleseismic P-to-S and S-to-P converted phases using the receiver function method. Three crustal discontinuities are observed: the Moho, ranging in depth between 38 and 47km and dipping to the south; and two intra-crustal discontinuities having depths of approximately 15 and 30km. The crustal discontinuities undulate laterally and often lose continuity, possibly indicating an imbricated structure and/or regions of velocity gradients. In the shallow lithosphere, a positive discontinuity is imaged at approximately 65km depth and is consistent with earlier refraction and wide-angle reflection results. Additionally, two zones of negative receiver function amplitudes at 55km depth are observed and are coincident with a region of anomalous tomographic low P- and S-wave velocities as well as a zone of high electrical conductivity. The images for the crust and shallow upper-mantle, when integrated with previous geophysical studies, are consistent with ideas of continental root formation due to imbrication of Archean subducted material and accretion of island arcs observed in surface geology. [Copyright &y& Elsevier]

Mountain building in the western part of the Archean Superior Province culminated with the formation of regional strike-slip faults. This paper reports on the kinematics and timing of several major faults at the juncture between the Uchi, English River, Winnipeg River, and western Wabigoon subprovinces. Sinistral-oblique mylonitization along the northeast-striking Miniss River fault occurred at 2681 [ABSTRACT FROM AUTHOR]

Canadian society faces a significant decline in the number of active mines and in the discovery rate of base and precious metal deposits. Exploring in the shadows of active and former mines with improved metallogenic models and new technologies is one way to address this problem. Another way is to diversify mineral exploration outside known mining camps and target prospective but underexplored settings and nonconventional mineral deposits. In Canadian terms, diversifying exploration commonly translates into targeting gneissic and granitic terrains where modern geoscience knowledge may be rare or only at reconnaissance scale and where key regional and local indicators and vectors to ore may be missing in the geological record. Though underexplored settings abound in Canada, only one orogen has an aura that discourages exploration: the Grenville Province. Consequently, even though the Grenville Province provides the best model of a deep continental-collision zone so far studied anywhere on Earth and constitutes a microcosm of continental accretion, it remains underexplored, underprospected, undermapped and underestimated. It is thus essential to revisit the mineral potential of the most accessible orogen of the Canadian Shield, search for its missing volcanic belts, reexamine its ore deposits and mineral occurrences, and explore new research avenues using the best remote-sensing device on Earth: human eyes. This special issue captures advances associated with regional field investigations by government that played a special role in opening up frontier areas for mineral exploration. Papers stemming from academia and government–university–industry consortiums investigate further some of the topics covered by these and earlier surveys and others contribute structural and metamorphic insights that will be valuable in future mapping projects. The advances reported here for the Grenville Province may provide impetus to revisit other Grenville-age terrains worldwide, just as metallogenic models developed in other countries have provided the means to look in a different manner at the Grenville orogen for mineral deposits. Collectively all the various approaches presented in this volume help us to revamp our way of looking at the mineral potential of the Grenville orogen. [ABSTRACT FROM AUTHOR]

The Fire Lake formation of the Yukon-Tanana terrane in the Finlayson Lake region, Yukon, Canada, consists primarily of Late Devonian (ca. 365–360 Ma) mafic metavolcanic rocks and smaller volumes of mafic and ultramafic subvolcanic metamorphosed intrusions. In this paper, field, geochemical, and Nd isotope attributes of these rocks are presented in an attempt to understand their tectonic setting, the magmatic processes involved in their formation, and their roles in Cordilleran crustal growth. The mafic rocks of the Fire Lake formation exhibit a wide diversity of geochemical signatures and are classified into seven chemically defined suites: (1) backarc-basin basalt, (2) enriched mid-oceanic-ridge basalt (E-MORB), (3) oceanic-island basalt (OIB), (4) Th-rich OIB, (5) boninite, (6) island-arc tholeiite, and (7) fight rare earth element (LREE)—enriched island-arc tholeiite. The diversity of geochemical signatures is interpreted to represent variable mixtures of asthenospheric (MORB-type) mantle, subarc mantle wedge, and lithospheric (OIB-type) mantle with or without elemental contributions from the subducted slab and/or continental crust. These suites of rocks are also associated with fine-grained basinal sedimentary facies, variations in metavolcanic and metasedimentary unit thickness, extensional synvolcanic faults, and apparent extensional-fault—controlled emplacement of mafic intrusive rocks and hydrothermal volcanic-hosted massive sulfide mineralization. The suites also exhibit a broad spatial distribution; those with “arc” signatures (Nb/Thmn. < 1; mn—normalized to primitive mantle values) are located primarily in the western parts of the formation, and suites with “nonarc” signatures (Sb/Thmn ≥ 1) are located primarily within the eastern parts of the formation. Collectively, these geologic and geochemical attributes are interpreted to stem from the transition from arc magmatism to the initiation of an extensional backarc basinal environment associated with an east-dipping subduction zone. The initiation of backarc-basin magmatism recorded in the Fire Lake formation was part of a much larger Late Devonian backarc basinal system forming along the western edge of the margin of North America. The Fire Lake formation is interpreted to represent (1) the commencement of Yukon-Tanana arc rifting and separation from the North American cratonic margin, and (2) the initiation of a marginal (backarc) basin (now the Slide Mountain terrane) inboard of the Yukon-Tanana arc system. This tectonic evolution likely occurred either as a result of slab rollback toward the west within the convergent margin responsible for Yukon-Tanana arc activity or as a result of the propagation of the Slide Mountain backarc-basin spreading ridges into the Yukon-Tanana arc system. This Yukon-Tanana arc rifting episode was also broadly coincident with rifting and hydrothermal activity within rocks of the North American craton. The geochemical and isotopic signatures of magmatic rocks in the Fire Lake formation have some features similar to intraoceanie arc rocks (e.g., boninites, island-arc tholeiites), and many have juvenile Nd isotope signatures (i.e., εNd(t) > 0; most have εNd(t) > +5), suggesting that the pericratonic terranes of the northern Cordillera have a significant juvenile component. If this is the case throughout the Yukon-Tanana terrane, then the pericratonic terranes may have contributed much more juvenile material to Cordilleran crustal growth in the Phanerozoic than has previously been considered. [ABSTRACT FROM AUTHOR]

The remote-sensing study of an exhumed upper Paleozoic surface in the southern Gaspé Peninsula of Quebec has provided indirect evidence for the presence of a previously unidentified post-Acadian (post—Middle Devonian orogeny) graben-fill unit. Subsequent work on stratigraphic sections in that area confirms that the graben-fill unit, the new Saint-Jules Formation, is indeed petrographically distinct and older than previously documented upper Paleozoic strata in that area, which were collectively assigned to the Viséan (Upper Mississippian) Bonaventure Formation. Paleogeographic reconstruction from sedimentary facies, paleocurrent, and provenance studies concurs with the geometric detail that was provided by the preliminary geomorphic study. The present paper therefore presents the case study of an upper Paleozoic stratigraphic unit that was first inferred by geomorphic constraints prior to being recognized in the field through the study of stratigraphic sections. The study underlines the stratigraphic relevance of analyzing exhumed paleosurfaces at the margins of ancient sedimentary basins. [ABSTRACT FROM AUTHOR]

There are two unreconciled interpretations for the age and character of the boundary separating the Cambrian–Ordovician Potsdam and Beekmantown groups that underlie the Ottawa Embayment in eastern Ontario. These stratal groups consist of interior facies of the central Laurentian Platform. As exposed in the type section of the Nepean Formation (upper Potsdam Group), located in the City of Ottawa, the boundary was previously interpreted to be conformable and of Early Ordovician age. This intepretation was of enormous impact on subsequent regional geology compilations that showed a diachronous boundary across the platform interior. From recent subsurface analysis across eastern Ontario, the contact was interpreted to be disconformable, a sequence boundary separating Late Cambrian and Early Ordovician strata. This paper reexamines the type section. Lithologically, the group boundary should be repositioned downsection by ~1.5 m. The contact now lies coincident with a disconformity that has a paleorelief of < 10 cm. The proposed revision is geologically significant. Previous collections of Early Ordovician conodonts from the type section, used to define the age of what had been interpreted to be upper Potsdam strata, now fall entirely within the lower Beekmantown Group. Nepean (Potsdam) strata exposed in the type section remain undated. Regional correlation of the disconformity across the Laurentian platform suggests that Nepean strata at the type section are likely of Late Cambrian age. There now exists a regionally coherent separation of Cambrian and Ordovician sedimentation patterns in the Ottawa Embayment. [ABSTRACT FROM AUTHOR]

A petroleum pool, that has a common petroleum/water contact and a distinctive pressure regime, is a fundamental unit of petroleum accumulation, and can be treated as a natural object. The prediction of the undiscovered petroleum pool locations can be performed employing a method similar to that used to predict sand channels in a clastic reservoir formation. This paper presents an example for the prediction of possible locations of undiscovered petroleum pools in the western Sverdrup Basin, Arctic Canada using an object-based model. This model simultaneously considers the information from the basic geological conditions for the formation of petroleum pools and the spatial correlation among the pools. The simulated results indicate that the object-based model improves predictions of petroleum occurrences by incorporating spatial correlation information into the model and by checking the consistency of the model with geological constraints. [Copyright &y& Elsevier]

Although alkalic porphyry Au--Cu deposits are much less common than their calc-alkalic counterparts, they represent attractive exploration targets both due to their occurrence as, locally concealed, clusters and their high Au contents. In this paper, the geology of the Mt. Milligan Au--Cu deposit, Canada, and its geophysical footprint on magnetic and AEM data is used as a case-study for the exploration and discovery of concealed alkalic porphyry Au--Cu deposits. The Cole-Cole parameters in the AEM data are extracted using an improved Airborne Induced Polarization (AIP) mapping algorithm. We propose that the subtle electromagnetic signatures of disseminated sulfides around the intrusive porphyry stocks at Mt. Milligan could be mapped by the m τ product, where m is AIP apparent chargeability, and τ the Cole-Cole time-constant, provided that the depths of the alteration zone does not exceed 75 m. The product is called Tau-Scaled Chargeability or TSC. In order to improve the exploration success in the search for concealed alkalic porphyry Au--Cu deposits, we propose to: (1) concentrate the exploration on known and well-endowed mineral districts; and (2) apply innovative digital data-processing techniques capable of extracting weak and subtle signatures from airborne geophysical data and, subsequently, to utilize DCIP ground surveys in the follow-up of anomalies, ideally in combination with enzyme-leach soil sampling. • Alkalic porphyry Au-Cu deposits are attractive exploration targets due to their high Au contents. • They occur in clusters, typically above fractionating magma chambers in the upper crust. • AIP mapping can define pyrite halos around concealed intrusive stocks at Mt. Milligan. • AIP mapping can be used as a vectoring tool. [ABSTRACT FROM AUTHOR]