Implications of metal dispersion from submarine hydrothermal systems for mineral exploration on mid-ocean ridges and in island arcs

Nature ◽  
1976 ◽  
Vol 262 (5569) ◽  
pp. 567-569 ◽  
Author(s):  
D. S. CRONAN
Keyword(s):  
Mineral Exploration ◽  
Hydrothermal Systems ◽  
Metal Dispersion ◽  
Island Arcs ◽  
Ocean Ridges ◽  
Submarine Hydrothermal Systems

The Ferguson Lake deposit: an example of Ni–Cu–Co–PGE mineralization emplaced in a back-arc basin setting?

2018 ◽  
Vol 55 (8) ◽  
pp. 958-979 ◽  
Author(s):  
P. Acosta-Góngora ◽  
S.J. Pehrsson ◽  
H. Sandeman ◽  
E. Martel ◽  
T. Peterson
Keyword(s):  
Mineral Exploration ◽  
Ultramafic Rocks ◽  
Geodynamic Setting ◽  
Ocean Ridges ◽  
Tectonic Environment ◽  
Pge Mineralization ◽  
Extensional Tectonic ◽  
Basaltic Composition ◽  
Greenstone Belts ◽  
Back Arc

The world’s largest Ni–Cu–Platinum group element (PGE) deposits are dominantly hosted by ultramafic rocks within continental extensional settings (e.g., Raglan, Voisey’s Bay), resulting in a focus on exploration in similar geodynamic settings. Consequently, the economic potential of other extensional tectonic environments, such as ocean ridges and back-arc basins, may be underestimated. In the northeastern portion of the ca. 2.7 Ga Yathkyed greenstone belt of the Chesterfield block (western Churchill Province, Canada), the Ni–Cu–Co–PGE Ferguson Lake deposit is hosted by >2.6 Ga hornblenditic to gabbroic rocks of the Ferguson Lake Igneous Complex (FLIC), which is metamorphosed up to amphibolitic facies. The FLIC has a basaltic composition (Mg# = 31–72), flat to slightly negatively sloped normalized trace element patterns (La/YbPM = 0.7–3.5), and negative Zr, Ti, and Nb anomalies. The FLIC rocks are geochemically similar to the 2.7 Ga back-arc basin tholeiitic basalts from the adjacent Yathkyed and MacQuoid greenstone belts (Mg# = 30–67; La/YbPM = 0.3–3.0), but the Ferguson Lake intrusions appear to be more crustally contaminated. We interpret the FLIC to have formed in an equivalent back-arc basin setting. This geodynamic setting is rare for the formation of Ni–Cu–PGE occurrences, and only few examples of this tectonic environment (or variations of it, e.g., rifted back-arc) are found in other Proterozoic and Archean sequences (e.g., Lorraine deposit, Quebec). We suggest that back-arc basin-derived mafic rocks within the Yathkyed and other Neoarchean greenstone belts of the Chesterfield block (MacQuoid and Angikuni) could represent important targets for future mineral exploration.

Near-Bottom Magnetic Signatures of Submarine Hydrothermal Systems at Marsili and Palinuro Volcanoes, Southern Tyrrhenian Sea, Italy

2014 ◽  
Vol 109 (8) ◽  
pp. 2119-2128 ◽  
Author(s):  
F. Caratori Tontini ◽  
G. Bortoluzzi ◽  
C. Carmisciano ◽  
L. Cocchi ◽  
C. E. J. de Ronde ◽  
...  
Keyword(s):  
Hydrothermal Systems ◽  
Tyrrhenian Sea ◽  
Magnetic Signatures ◽  
Submarine Hydrothermal Systems ◽  
Southern Tyrrhenian Sea

The effect of geometry on the gravitational instability of a buoyant region of viscous fluid

1989 ◽  
Vol 202 ◽  
pp. 577-594 ◽  
Author(s):  
John R. Lister ◽  
Ross C. Kerr
Keyword(s):  
Growth Rate ◽  
Stokes Equations ◽  
Gravitational Instability ◽  
Cube Root ◽  
Scaling Analysis ◽  
Island Arcs ◽  
Layered Systems ◽  
Ocean Ridges ◽  
The Difference ◽  
The Stability

The low-Reynolds-number stability of a region of buoyant fluid surrounded by denser fluid is analysed in two situations. In the first study, the buoyant fluid lies in a thin layer sandwiched between two denser and much deeper layers. The growth rate and wavelength of the most unstable sinusoidal perturbation are calculated and the effects of the viscosity ratios and density differences between the fluids are investigated. It is found that if the buoyant fluid is much less viscous than the overlying fluid then, in quite general circumstances, both the most unstable wavelength and the corresponding growth rate are inversely proportional to the cube root of the viscosity of the buoyant fluid. A physical explanation of this result is given by scaling analysis of the total dissipation. In the second study, the buoyant fluid takes the form of a cylinder rising through a uniform environment. The eigenmodes of small perturbation about this state of motion are found for each axial wavenumber in terms of Fourier series of separable solutions to the Stokes equations. In contrast to the first study, it is found that the most unstable wavelength and growth rate are asymptotically independent of the viscosity of the buoyant fluid when this viscosity is small.The difference between the results of the two studies is of importance, particularly for geophysical applications in which viscosity ratios are very large. Previous models of linear regions of volcanism at mid-ocean ridges and at island arcs have assumed that results obtained in simple two-layered systems can be generalized to other geometries. The conclusions of these models are discussed in the light of the stability results for a cylindrical (and hence linea.

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