Article: Time Scales of Porphyry Cu Deposit Formation: Insights from Titanium Diffusion in Quartz
Authors: C.N. Mercer, M.H. Reed, C.M. Mercer
Publication: Economic Geology, Vol. 110, No. 3, p. 587-602
This study brings a new quantitative interpretation of quartz zoning, a feature commonly observed in hydrothermal ore deposits, using trace element titanium diffusion profiles to reconstruct time scales of porphyry deposit mineralization. Diffusion modeling is commonly used in igneous petrology, but this study represents one of the first, if not the first, time it has been applied to hydrothermal processes. Thus, it adds a new dimension to our understanding of the duration of ore-forming events, and demonstrates insightful and effective application of a variety of state-of-the-art analytical tools to hydrothermal research. The work represents innovative science applied to a practical problem of great interest to numerous researchers and explorationists. This paper will surely have a lasting impact in the field of economic geology.
Article: The Anatomy of a Buried Submarine Hydrothermal System, Clark Volcano, Kermadec Arc, New Zealand
Authors: C.E.J. de Ronde, S.L. Walker, R.G. Ditchburn, F. Caratori Tontini, M.D. Hannington, S.G. Merle, C. Timm, M.R. Handler, R.J. Wysoczanski, V.M. Dekov, G.D. Kamenov, E.T. Baker, R.W. Embley, J.E. Lupton, P. Stoffers
Publication: Economic Geology, Vol. 109, No. 8, p. 2261-2292
This innovative study uses integrated submarine mapping, mineralogy, radiogenic and stable isotopes to model extinct and currently active hydrothermal activity as a function of volcano extension and growth. The paper has important implications for the longevity and cyclicity of VMS hydrothermal systems and illustrates the role that submarine volcanic environment plays on the nature of mineralization. The work has implications for global resource assessments as we have likely underestimated the abundance of mineralization in modern environments.
Article: The Metal Content of Silicate Melts and Aqueous Fluids in Subeconomically Mo Mineralized Granites: Implications for Porphyry Mo Genesis
Authors: L. Lerchbaumer, A. Audétat
Publication: Economic Geology, Vol. 108, No. 5, p. 987-1013
This innovative study provides compelling evidence for the origin of granite-hosted molybdenum mineralization including the critical conclusion that barren granitic systems do not necessarily have lower molybdenum contents, relative to those of productive granites. It judiciously uses modern analytical techniques on melt inclusions coupled with experiments and a thoughtful analysis of the existing data on molybdenum and associated metals distribution in magmatic systems.
Article: Hydrologic, Magmatic, and Tectonic Controls on Hydrothermal Flow, Taupo Volcanic Zone, New Zealand: Implications for the Formation of Epithermal Vein Deposits
Authors: J.V. Rowland, S.F. Simmons
Publication: Economic Geology, Vol. 107, No. 3, p. 427-457
This carefully constructed and elegantly written paper with superb graphics excels in its technical excellence, innovation, and likely lasting impact that it will have in the field of economic geology — all attributes valued in the Brian J. Skinner Award selection process. The research relies on basic observations and integrates the tectonic, volcanic, and hydrothermal histories of the Taupo Volcanic Zone into a cohesive model that explains the evolution of permeability and fluid flow in the region as it relates to epithermal mineralization. The work has important implications for the exploration for epithermal ore deposits.
Article: A Carbonaceous Sedimentary Source-Rock Model for Carlin-Type and Orogenic Gold Deposits
Authors: R.R. Large, S.W. Bull, V.V. Maslennikov
Publication: Economic Geology, Vol. 106, No. 3, p. 331-358
This beautifully written paper excels in its technical excellence, innovation, and likely lasting impact that it will have in the field of economic geology – all attributes valued in the Brian J. Skinner Award selection process. The research integrates modern, cutting-edge analytical techniques with tectonic, geochemical, and isotopic insights to address a problem that has perplexed economic geologists for decades. The combination of basic science and practical application of this work is to be commended. This paper will fundamentally change our ideas about processes involved in the formation of orogenic and Carlin-type gold deposits.
Article: Evolution of Calc-Alkaline Volcanism and Associated Hydrothermal Gold Deposits at Yanacocha, Peru
Authors: A.A. Longo, J.H. Dilles, A.L. Grunder, R. Duncan
Publication: Economic Geology, Vol. 105, No. 7, p. 1191-1241
Fantastic paper that integrates field mapping, regional stratigraphy, local stratigraphy, and alteration with geochronology and petrology to provide a true understanding of the setting and timing of mineralization and associated alteration at this important epithermal system, and also provides key constraints on how these systems form, their timing, and longevity.
Article: Cordilleran Epithermal Cu-Zn-Pb-(Au-Ag) Mineralization in the Colquijirca District, Central Peru: Deposit-Scale Mineralogical Patterns
Authors: R. Bendezú, L. Fontboté
Publication: Economic Geology, Vol. 104, No. 7, p. 905-944
This beautifully written paper with superb graphics excels in its technical excellence, innovation, and likely lasting impact that it will have in the field of economic geology—all attributes valued in the Skinner Award selection process. The research, spanning scales of observation from deposit to microscopic scale, intelligently uses district-scale mapping and geochemistry to provide new insight to the geological and geochemical processes that formed the deposit. The integration of field and laboratory investigations leads to the recognition of a complex paragenesis and multi-stage evolution of this epithermal setting and provides understanding directly applicable to exploration.
Article: Fluid Inclusion Evidence for Magmatic-Hydrothermal Fluid Evolution in the Porphyry Copper-Molybdenum Deposit at Butte, Montana
Authors: B.G. Rusk, M.H. Reed, J.H. Dilles
Publication: Economic Geology, Vol. 103, No. 2, p. 307-334
This paper presents a thorough and innovative approach to investigating a challenging topic—the hydrothermal evolution of a complex, world class porphyry copper system. The authors elegantly document, through detailed fluid inclusion studies, the importance of physical and chemical changes in the evolution a single, low salinity hydrothermal fluid rather than invoking multiple fluids as has been proposed for numerous other porphyry systems. Their study further describes how differing precipitation mechanisms account for the copper and molybdenum mineralization. Finally, their results suggest that Butte formed at some of the greatest depths known for economic porphyry copper-style mineralization—a thought provoking conclusion.
Article: The LaRonde Penna World-Class Au-Rich Volcanogenic Massive Sulfide Deposit, Abitibi, Québec: Mineralogy and Geochemistry of Alteration and Implications for Genesis and Exploration
Authors: B. Dubé, P. Mercier-Langevin, M. Hannington, B. Lafrance, G. Gosselin, P. Gosselin
Publication: Economic Geology, Vol. 102, No. 4, p. 633-666
This paper is one of the few detailed studies of a world-class gold-rich volcanogenic massive sulfide deposit, the LaRonde-Penna deposit, which arguably may be the “type example” for this economically important style of mineralization. The study is an eloquent integration of geological, mineralogical, and geochemical information that provides concrete recommendations for exploration. The authors present compelling evidence bearing on one of the classic debates in economic geology regarding magmatic versus non-magmatic (seawater) contributions to VMS systems. They propose a new model for the relationship between low- and high-sulfidation sea-floor systems, and in contrast to earlier models suggest that both end-members can form in the same district or even within a single hydrothermal system.
Article: Igneous Geology of the Carlin Trend, Nevada: Development of the Eocene Plutonic Complex and Significance for Carlin-Type Gold Deposits
Authors: M.W. Ressel, C.D. Henry
Publication: Economic Geology, Vol. 101, No. 2, p. 347-383
This paper is the product of a significant effort to increase the awareness of igneous rocks and magmatic activity in the Carlin Trend. It characterizes and contrasts Jurassic, Cretaceous, Eocene, and Miocene intrusions in the northern Great Basin using a diverse data set of emplacement styles, mineralogy, compositions and hard-won Ar-Ar ages. These data provide a comprehensive temporal framework for igneous rocks that are spatially associated with more than 40 gold deposits of the Carlin Trend. The paper integrates a large amount of new and previously published information and succeeds in the technically and conceptually challenging task of combining geological mapping, geochronology, igneous petrology and geophysics to address a major question in economic geology.
Article: Evolution of a Submarine Magmatic-Hydrothermal System: Brothers Volcano, Southern Kermadec Arc, New Zealand
Authors: C.E.J. de Ronde, M.D. Hannington, P. Stoffers, I.E. Wright, R.G. Ditchburn, A.G. Reyes, E.T. Baker, C.J. Massoth, J.E. Lupton, S.L. Walker, R.R. Greene, C.W.R. Soong, J. Ishibashi, G.T. Lebon, C.J. Bray, J.A Resing
Publication: Economic Geology, Vol. 100, No. 6, p. 1097-1133
This paper presents an elegant and detailed dissection of an active submarine hydrothermal system in a critical transitional geologic environment. Economic geologists have long recognized the significance of volcanic arcs as favorable terrains for mineralization. However, ore deposits typically form a bimodal distribution with end members divided between terrestrial and submarine representatives. The innovative combination of geologic and geochemical studies that form the basis of this contribution provides unique insights of the interplay between magmatic fluids and evolved seawater in ore-forming systems on the sea floor.
Article: Henderson Porphyry Molybdenum System, Colorado: I. Sequence and Abundance of Hydrothermal Mineral Assemblages, Flow Paths of Evolving Fluids, and Evolutionary Style
Authors: E. Seedorff, M.T. Einaudi
Publication: Economic Geology, Vol. 99, No. 1, p. 3-37
This paper presents a comprehensive and detailed analysis of the geology, alteration and mineralization of a classic and economically significant porphyry molybdenum deposit. The geological mapping, core logging and paragenetic studies that form the basis of this paper reflect the careful field and laboratory observations necessary to constrain the history of mineralization and to present a full and complete picture of a complex mineralizing system. The body of observations on Henderson clearly show how multiple overprinting hydrothermal events lead to the formation of world-class orebodies. Together with the companion paper on the geochemical evolution of the Henderson system, this work provides new insight into the essential processes that form porphyry deposits and sets a new standard for their documentation.
Article: Geology of the Bajo de la Alumbrera Porphyry Copper-Gold Deposit, Argentina
Author: J.M. Proffett
Publication: Economic Geology, Vol. 98, No. 8, p. 1535-1574
This paper presents an exhaustive descriptive account of the geology, alteration and mineralization of a complex, economically significant porphyry copper-gold deposit. The geological mapping, which forms the basis for this contribution, exemplifies the type of careful fieldwork and observations necessary to reliably constrain the history of these deposits and to present a full and complete picture of the mineralizing process. The body of observations in this paper is the result of an exceptional effort, both in the field and in the preparation of the accompanying maps. It is an example of how detailed geological observations underpin the interpretation of ore-forming systems and how our science relies on this effort. The carefully prepared maps are expected to have a significant impact in both research and teaching and are an important milestone for the journal. They set a high standard of technical excellence for future contributions of this type.
Article: Miocene Landscape Evolution and Geomorphologic Controls on Epithermal Processes in the El Indio-Pascua Au-Ag-Cu Belt, Chile and Argentina
Author: T. Bissig, A.H. Clark, J.K.W. Lee, C.J. Hodgson
Publication: Economic Geology, Vol. 97, No. 5, p. 971-996
This paper presents an integrated study of the geochronology, mineralization and landscape evolution in the El Indio-Pascua belt. Taking advantage of the superb exposures of the Andes, the authors combine innovative geomorphologic reconstructions (aided by GIS technology), high-precision geochronology, and ore deposit geology to show how changing landscape can influence fluid evolution and affect mineralizing processes. Despite the implied importance of the paleosurface in epithermal environments, the means to link landscape evolution to mineralizing processes has eluded economic geologists. The approach presented in this paper is considered both innovative and provocative and hopefully stimulate new discussion and research on the role of surface evolution in the paleohydrology of ore-forming systems.