Lithological and spatial controls on the distribution of quartz veins in andesite- and rhyolite-hosted epithermal Au-Ag deposits of the Hauraki Goldfield, New Zealand

Brathwaite, Robert L.; Cargill, Hugh; Christie, Anthony B.; Swain, Andrew

doi:10.1007/s001260050282

Cited by 37 publications

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“…The vein thickness data from Cornwall and Vung Tau are consistent with those reported for vein systems in other igneous lithologies (McCaffrey et al 1993;Braithwaite et al 2001;Gudmundsson et al 2001). A power-law exponent of 0.8 was given as the mode for 1-D samples through veins developed in a range of metamorphic and sedimentary lithologies (Gillespie et al 1999).…”

Section: Fracture Size Datasupporting

confidence: 83%

“…In igneous rocks, vein spacing distributions reported by Braithwaite et al (2001) show non-power-law spacing distributions. For sedimentary and metasedimentary rocks, the observed spacing distribution appears to vary as a function of the type of fracturing, the host-rock lithology and the conditions of deformation (Gillespie et al 1999(Gillespie et al , 2001.…”

Section: Fracture Spacing Datamentioning

confidence: 98%

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Fracture formation and evolution in crystalline rocks: Insights from attribute analysis

McCaffrey

Sleight

Pugliese

et al. 2003

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Fractures are ubiquitous in crystalline rocks and control the strength and geophysical and fluid transport characteristics of the Earth's upper crust. A quantitative description of fracture attributes may constrain models of fracture formation and evolution. In this study, fracture attributes collected from one-dimensional samples across exposures of typical crystalline rocks show comparable variability in fracture size and spacing to sedimentary rocks. Vein thickness and fracture aperture data show predominately power-law distributions. Vein and fracture spacing data are best described by exponential distributions with negative slopes and appear to vary with composition in intrusive rocks. The fracture systems exhibit a range of anti-clustered to clustered patterns, and densities are an order of magnitude higher for joints compared to veins. Fracture clustering data can be used in conjunction with the spatial distributions to provide information on the controlling processes of fracture spacing. We suggest that exponential spacing distribution is produced as a sampling effect for both periodic-spaced and clustered fracture sets. In the examples given here, thermal stress-related joint patterns are distinguishable from tectonic-related fractures in plutonic rocks and fracture density and clustering is increased towards a major reactivated basement fault.

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Section: Fracture Size Datasupporting

confidence: 83%

Section: Fracture Spacing Datamentioning

confidence: 98%

Fracture formation and evolution in crystalline rocks: Insights from attribute analysis

McCaffrey

Sleight

Pugliese

et al. 2003

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“…Similar morphological zonation has also been discovered in epithermal deposits (Brathwaite et al, 2001) and porphyry deposits (André-Mayer and Sausse, 2007).…”

Section: Accepted M Manuscriptmentioning

confidence: 70%

Fluid focusing and its link to vertical morphological zonation at the Dajishan vein-type tungsten deposit, South China

Liu

Xing

Zhang

2014

Ore Geology Reviews

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Five-floor vertical zonation in vein morphology is a common phenomenon in exo-contact vein-type tungsten deposits of South China and has been widely applied for practical exploration, but the causative mechanisms are poorly understood. We combine fractal methods and finite element based numerical analysis to investigate the link between the fluid focusing and the vertical morphological characteristics at the Dajishan tungsten deposit and to determine vein growth mechanisms. Fractal analysis of vein morphology indicates that the growth mechanisms of veins in the lower part of ore bodies were mainly controlled by growth rate. Anisotropic permeability tensor method is applied to evaluate the anisotropic flow behaviours in joints. Numerical experiments on permeability ratio and aspect ratio controlled by stress state indicate that the NWW-striking joints in the host rock significantly affect the fluid focusing in these joints and the other potential conduits.The higher permeability and aspect ratios in the lower levels of the joint systems lead to the more fluid focusing in the lower part of ore bodies, which delivers more fluids required for precipitating silica. The five-floor zonation at this deposit is related to the regional tectonic evolution from the Indosinian (257~205 Ma) to Yanshanian (205~135 Ma) in South China. This paper may also help to better understand the vertical morphological zonation in this type of tungsten deposits in China.

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“…56, no. 1, 2006 Statistical and Johnston, 1996; Gillespie et al, 1999;Loriga, 1999;Roberts et al, 1999;Brathwaite et al, 2001), cumulative frequencies of vein thickness obey the power-law distributions. They indicate a positive feedback process (Manning, 1994;Clark et al, 1995).…”

Section: Stage Of Vein Developmentmentioning

confidence: 99%

“…Physico-chemical environments of the fracture systems (i.e., tectonic setting, host rock type, temperature and pressure) affect their evolution (e.g., Paterson, 1978;Scholz, 1990). Statistical features of fracture systems (e.g., cumulative profile, size-frequency distribution and fractal size: e.g., Turcotte, 1997;Bonnet et al, 2001) are useful for elucidating the timing during their evolution (e.g., Rives et al, 1992;Cowie et al, 1995;Ackermann et al, 2001) and their physico-chemical environments (e.g., Velde et al, 1993;Gillespie et al, 1999;Brathwaite et al, 2001). Vein systems, which are of the fracture systems filled by minerals at their formation stages, could be argued by the same manner.…”

Section: Introductionmentioning

confidence: 99%

Statistical Features of Vein Systems in the Hishikari Epithermal Gold Deposit, Japan

Sasaki¹

2006

Resource Geology

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Abstract:The Hishikari epithermal gold deposit consists of parallel vertical veins hosted by the Quaternary volcanic rocks (QVR) and Cretaceous sedimentary rocks (CSR) at the shallow and deep levels, respectively. In order to reveal the lithological influence on the evolution of vein systems in the Hishikari field, vein density, width, spacing and position were statistically examined using cores sampled from three boreholes.The statistical features of the veins identified were summarized as follows. The feature (i) indicates higher ductility of the QVR against fracturing than the CSR. The feature (ii) implies that large deformation was accumulated in rocks themselves (e.g., alteration zones) in addition to the veins examined in the QVR compared to only the veins in the CSR. The feature (iv) suggests that the vein systems in the CSR reached a stage at which the several selected large veins grew as main conduit, that potentially provided pathways for ore-forming fluids to ascend from deep levels. The coefficients of variation of vein spacing and fractal dimensions of vein position (features v and vi) indicate clustered distribution of the veins in the field.This study might be helpful for a better understanding of lithological influence on the evolution of vein systems not only in the Hishikari field but also in other fields.

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Lithological and spatial controls on the distribution of quartz veins in andesite- and rhyolite-hosted epithermal Au-Ag deposits of the Hauraki Goldfield, New Zealand

Cited by 37 publications

References 0 publications

Fracture formation and evolution in crystalline rocks: Insights from attribute analysis

Fracture formation and evolution in crystalline rocks: Insights from attribute analysis

Fluid focusing and its link to vertical morphological zonation at the Dajishan vein-type tungsten deposit, South China

Statistical Features of Vein Systems in the Hishikari Epithermal Gold Deposit, Japan

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