Theoretical analysis of the role of groundwater flow in the genesis of stratabound ore deposits; 1, Mathematical and numerical model

Garven, Grant; Freeze, R. Allan

doi:10.2475/ajs.284.10.1085

Cited by 321 publications

(113 citation statements)

References 0 publications

Supporting

Mentioning

110

Contrasting

Unclassified

Order By: Relevance

“…Pelo menos em parte, tais fluidos parecem ter percolado a unidade argilo-dolomítica superior, indicando fluxo descendente dos fluidos. Assim a migração de fluidos mais superficias, frios (< 100 o C), reduzidos e ricos em enxofre no sistema hidrotermal pode ter sido controlada pela topografia e gravidade, de modo análogo ao proposto para depósitos do tipo Mississippi Valley (Garven & Freeze 1984). A mistura desses fluidos com fluido metalífero mais quente (> 200 o C), que teria circulado pelas partes mais profundas da bacia, poderia explicar a tendência de covariância isotópica definida pela dolomita hidrotermal.…”

unclassified

Sistemática de isótopos de oxigênio e carbono aplicada ao estudo da evolução metalogenética do depósito de Zn-Pb de Morro Agudo (MG)

Rubo

Monteiro

2010

RBG

View full text Add to dashboard Cite

Resumo A Faixa Vazante-Paracatu representa o distrito mineral responsável por toda a produção de zinco do Brasil. Nessa faixa ocorrem depósitos com tipologias distintas de minério, com predominância de sulfetos (esfalerita, galena, pirita, marcassita), como em Morro Agudo, ou de silicato de zinco, como a willemita, em Vazante. No depósito de Zn-Pb de Morro Agudo as rochas hospedeiras (brechas dolomíticas e dolarenitos) apresentam evidências de dolomitização precoce, diagênese marinha, meteórica e de soterramento. Nesse depósito, três episódios de mineralização foram identificados, sendo associados a processos de (1) substituição da rocha hospedeira por esfalerita fina, (2) preenchimento de bolsões e veios por esfalerita, galena, pirita, marcassita, quartzo, dolomita hidrotermal e betume, e (3) formação de veios e vênulas tardios com esfalerita associada a estruturas rúpteis. As assinaturas isotópicas de oxigênio e carbono da dolomita diagenética indicam processos de interação fluido-rocha envolvendo os fluidos mineralizantes. A composição isotópica da dolomita hidrotermal, associada aos sulfetos, indica contribuição de fontes de carbono reduzido à evolução do sistema hidrotermal. Isso sugere a participação de fluidos que interagiram com a unidade argilo-dolomítica estratigraficamente superior aos dolomitos hospedeiros das mineralizações que contém carbono orgânico. Isso implicaria em participação de fluidos hidrotermais descendentes, mais frios e reduzidos, além dos fluidos ascendentes, quentes e metalíferos para a gênese das mineralizações de Zn-Pb. As composições isotópicas calculadas para os fluidos em equilíbrio com dolomita hidrotermal sugerem que tais fluidos ascendentes e descendentes seriam predominantemente formacionais semelhantes aos associados à gênese de depósitos de Pb-Zn do tipo Mississippi Valley.Palavras-chave: depósito de Zn-Pb, isótopos estáveis, rochas carbonáticas, Grupo Vazante. Abstract Oxygen and carbon isotopic systematic applied to the metallogenetic evolution of the ZnPb Morro Agudo deposit, MG, Brazil. The Vazante-Paracatu region represents the mineral district respon-sible for all the Brazilian zinc production. In this region, mineral deposits are characterized by predominantly sulphide-rich ores (sphalerite, galena, pyrite, marcasite), as in Morro Agudo, and silicatic ores with willemite at Vazante. In the Morro Agudo deposit, the host rocks (dolomitic breccias and dolarenites) have evidence of early dolomitization, besides marine, meteoric and burial diagenesis. Three mineralization episodes have been defined and are associated with processes of (1) replacement of host rock by fine-grained sphalerite, (2) open-space filling in vugs and veins by sphalerite, galena, pyrite, marcasite, quartz, hydrothermal dolomite and bitumen, and (3) formation of late veins and veinlets with sphalerite within brittle structures. The isotopic signatures of the diagenetic dolomite indicate processes of interaction with mineralizing fluids, while the isotopic composition of the hydrothermal dolomite, a...

show abstract

unclassified

Sistemática de isótopos de oxigênio e carbono aplicada ao estudo da evolução metalogenética do depósito de Zn-Pb de Morro Agudo (MG)

Rubo

Monteiro

2010

RBG

View full text Add to dashboard Cite

show abstract

“…Such numerical simulation issues may include: (1) an issue caused by the difference between an element used in the finite element method and a particle used in the distinct element method; (2) an issue resulting from using the explicit dynamic relaxation method to solve a quasistatic problem; and (3) an issue stemming from the inappropriate loading procedure used in the particle simulation method. Although some aspects of these numerical simulation issues were briefly discussed previously [29][30][31][32], we will discuss them in great details so that their impacts on the particle simulation results of spontaneous crack generation problems within large-scale quasi-static systems can be thoroughly understood.…”

Section: Introductionmentioning

confidence: 99%

“…Because of the ever-increasing demand for mineral resources in the contemporary world, exploration for new mineral resources has become one of the most priorities for many industrial countries. For this reason, extensive studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14] have been conducted to understand the detailed physical and chemical processes that control ore body formation and mineralization within the upper crust of the Earth. Since cracks play an important role in the creation of mineral-bearing fluid channels, the numerical simulation of spontaneous crack generation in brittle rocks within the upper crust of the Earth has become an important research topic in the field of computational geosciences.…”

Section: Introductionmentioning

confidence: 99%

Particle simulation of spontaneous crack generation problems in large‐scale quasi‐static systems

Zhao

Hobbs

Ord

et al. 2006

Numerical Meth Engineering

View full text Add to dashboard Cite

SUMMARYTo extend the application range of the distinct element method from a laboratory scale into a large scale such as a geological scale, we need to deal with an upscale issue associated with simulating spontaneous crack generation problems in large-scale quasi-static systems. Toward this direction, three important simulation issues, which may affect the quality of the particle simulation results of a quasi-static system, have been addressed in details in this paper. The first simulation issue is how to determine the particle-scale mechanical properties of a particle from the measured macroscopic mechanical properties of rocks. The second simulation issue is that the fictitious time, rather than the physical time, is used in the particle simulation of a quasi-static problem. The third simulation issue is that the conventional loading procedure used in the distinct element method is conceptually inaccurate, at least from the force propagation point of view. A new loading procedure is proposed to solve the conceptual problem resulting from the third simulation issue. The proposed loading procedure is comprised of two main types of periods, a loading period and a frozen period. Using the proposed loading procedure, the parameter selection problem stemming from the first issue can be somewhat solved. Since the second issue is an inherent one, it is strongly recommended that a particle-size sensitivity analysis of at least two different models, which have the same geometry but different smallest particle sizes, be carried out to confirm the particle simulation result of a large-scale quasi-static system. The related simulation results have demonstrated the usefulness and correctness of the proposed loading procedure for dealing with spontaneous crack generation problems in large-scale quasi-static geological systems.

show abstract

“…Although the fluid mass flux rate was widely used to describe the metamorphic fluid flow in the crust of the Earth, it is a derived and therefore non-unique quantity to describe the consequence of a resulting fluid flow. As we mentioned above, the fluid mass flux rate can be the consequence of a topography induced fluid flow [23,24], a buoyancy driven fluid flow (i.e. free convection flow) [14][15][16][17], a metamorphic fluid flow [7][8][9][10][11]13] and so forth.…”

Section: Introductionmentioning

confidence: 99%

Analysis of steady‐state heat transfer through mid‐crustal vertical cracks with upward throughflow in hydrothermal systems

Zhao

Hobbs

Mühlhaus

et al. 2002

Num Anal Meth Geomechanics

View full text Add to dashboard Cite

SUMMARYWe conduct a theoretical analysis of steady-state heat transfer problems through mid-crustal vertical cracks with upward throughflow in hydrothermal systems. In particular, we derive analytical solutions for both the far field and near field of the system. In order to investigate the contribution of the forced advection to the total temperature of the system, two concepts, namely the critical Peclet number and the critical permeability of the system, have been presented and discussed in this paper. The analytical solution for the far field of the system indicates that if the pore-fluid pressure gradient in the crust is lithostatic, the critical permeability of the system can be used to determine whether or not the contribution of the forced advection to the total temperature of the system is negligible. Otherwise, the critical Peclet number should be used. For a crust of moderate thickness, the critical permeability is of the order of magnitude of 10 À20 m 2 ; under which heat conduction is the overwhelming mechanism to transfer heat energy, even though the pore-fluid pressure gradient in the crust is lithostatic. Furthermore, the lower bound analytical solution for the near field of the system demonstrates that the permeable vertical cracks in the middle crust can efficiently transfer heat energy from the lower crust to the upper crust of the Earth.

show abstract

Theoretical analysis of the role of groundwater flow in the genesis of stratabound ore deposits; 1, Mathematical and numerical model

Cited by 321 publications

References 0 publications

Sistemática de isótopos de oxigênio e carbono aplicada ao estudo da evolução metalogenética do depósito de Zn-Pb de Morro Agudo (MG)

Sistemática de isótopos de oxigênio e carbono aplicada ao estudo da evolução metalogenética do depósito de Zn-Pb de Morro Agudo (MG)

Particle simulation of spontaneous crack generation problems in large‐scale quasi‐static systems

Analysis of steady‐state heat transfer through mid‐crustal vertical cracks with upward throughflow in hydrothermal systems

Contact Info

Product

Resources

About