Mass transfer and preferred orientation development during extensional microcracking in slate‐belt folds, Elura Mine, Australia

Roo, J. A. de

doi:10.1111/j.1525-1314.1989.tb00599.x

Cited by 12 publications

(1 citation statement)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The literature on structurally controlled vein-style mineral deposits, e.g., [7,8], has provided a number of theoretical concepts that link vein orientation and geometry with respect to the tectonic stresses. However, only a few studies have integrated regional tectonic context, vein shape and internal vein texture [19][20][21].…”

Section: Methodology: Structural Analysis Applied To Metallogenymentioning

confidence: 99%

Structural Control of Ore Deposits: The Role of Pre-Existing Structures on the Formation of Mineralised Vein Systems

Chauvet

2019

Minerals

View full text Add to dashboard Cite

The major role played by pre-existing structures in the formation of vein-style mineral deposits is demonstrated with several examples. The control of a pre-existing decollement level on the formation of a crustal extension-related (collapse) gold deposit is first illustrated in the Quadrilátero Ferrífero from Brazil. Shear zone and decollement structures were also examined and shown to control veins formation by three distinct processes: (i) re-aperture and re-using of wrench shear zones in the case of Shila gold mines (south Peru); (ii) remobilisation of metal in volcanic-hosted massive sulphide (VHMS) deposit by subsequent tectonic events and formation of a secondary stockwork controlled by structures created during this event (Iberian Pyrite Belt, Spain); (iii) formation of economic stockwork by contrasting deformation behaviours between ductile black schist versus brittle more competent dolomite (Cu-Ifri deposit, Morocco). Two examples involve changing of rheological competence within zones affected by deformation and/or alteration in order to receive the mineralisation (case studies of Achmmach, Morocco, and Mina Soriana, Spain). The last case underscores the significance of the magmatic-hydrothermal transition in the formation of mesothermal gold deposits (Bruès mine, Spain). All these examples clearly demonstrate the crucial role played by previously formed structures and/or texture in the development and formation of ore deposits.Minerals 2019, 9, 56 2 of 22 improve mining exploration strategies. I will present and discuss seven case studies of metal-bearing veins with different modes of formation that highlight the role of pre-existing features on their development. This aspect seems to be frequently underestimated, at least in the case of vein deposits, and this work aims to demonstrate its significance in the development of exploration and exploitation programs. The re-using of some previously formed structures has, in that case, a significant but passive role with respect to the formation of the economic feature. This concept is already exemplified in another contribution of this volume [18]. Each of the seven cases presented herein include a brief overview of the regional geology and deformation history, followed by a detailed geometrical and textural analysis of ore-bearing veins and a regional-scale genetic model that integrates these data. The relationships between neo-formed structures versus pre-existing ones will be highlighted in each case as well as its implications for regional vein distribution and, consequently, exploration programs.

show abstract

Section: Methodology: Structural Analysis Applied To Metallogenymentioning

confidence: 99%

Structural Control of Ore Deposits: The Role of Pre-Existing Structures on the Formation of Mineralised Vein Systems

Chauvet

2019

Minerals

View full text Add to dashboard Cite

show abstract

Regional fluid and metal mobility in the Dalradian metamorphic belt, Southern Grampian Highlands, Scotland

Craw

1990

Mineral. Deposita

View full text Add to dashboard Cite

Abstract.A prominent set of veins was formed during post-metamorphic deformation of the Caledonian Dalradian metamorphic belt. These veins are concentrated in dilational zones in fold hinges, but apophyses follow schistosity and fold axial surface fractures. The veins are most common in the cores of regional structures, especially the Dalradian Downbend and consist of quartz, calcite, chlorite and metallic sulphides and oxides. Metals, including gold, have been concentrated in the veins. The fluid which formed the veins was low salinity (1 -5 wt% NaC1 and KCI) COg-bearing (3-16 wt% CO2) water of metamorphic origin. The fluid varies slightly in composition within and between samples, but is essentially uniform in composition over several hundred km 2. Vein formation occurred at about 350+50~ and 200-300 MPa pressure. Further quartz mineralization occurred in some dilational zones at lower temperatures (160-180 ~ This later mineralization was accompanied by CO2 immiscibility. Dilution and oxidation of the metamorphic fluid occurred due to mixing with meteoric water as the rocks passed through the brittle-ductile transition. A similar metamorphic fluid is thought to have been responsible for gold mineralization in the nearby Tyndrum Fault at a later stage in the Dalradian uplift.Late Caledonian, post-metamorphic, metalliferous veins commonly occur in the Caledonian Dalradian metamorphic belt. Many of these veins are clearly associated with magmatic processes (Plant et al. 1983;Alderton 1985), but for others, the origin of the mineralizing fluid is not so clear (Pattrick et al. 1988). It is the purpose of this paper to show that metamorphic fluids formed an important part of the hydrothermal fluid flux through the Dalradian rocks in late Caledonian times, that these fluids carried metals, and that at least some of the post-meta-* Present address: Geology Department, University of Otago, P.O. Box 56, Dunedin, New Zealand morphic metalliferous deposits, particularly Au-bearing ones, may have been formed from such fluids.Fluid movement during uplift of a metamorphic belt is a well-established phenomenon. Fluids have been investigated in active mountain belts (Pecher 1979;Craw 1987;Holm et al. 1989), and in more deeply eroded belts (Hollister and Burruss 1976;Crawford et al. 1979), principally by fluid inclusion studies of veins. In most such studies, vein formation occurred throughout the uplift history of the metamorphic belt, representing long-continued fluid mobility. Thus numerous veins and generations of veins cross-cut earlier veins in a complex pattern of fluid pathways. Metallic mineralization commonly accompanies one or more of these vein generations (Kerrich and Fyfe 1981;McKeag and Craw 1989).In contrast to the above situation, portions of the Dalradian metamorphic belt of Scotland show only minor vein formation in the early and late stages of uplift. Instead, vein formation is concentrated into a relatively narrow part of the uplift history. This vein generation coincides with the formation of a set of struc...

show abstract

Fluid inclusion and sulphur isotope evidence for syntectonic mineralisation at the Elura mine, southeastern Australia

Seccombe

1990

Mineral. Deposita

View full text Add to dashboard Cite

Abstract. Fluid inclusion and sulphur isotope data for the discordant, metasediment-hosted massive sulphide deposit at Elura are consistent with a syntectonic origin of the orebodies. Thermometric and laser Raman microprobe analyses indicate that two-phase, primary fluid inclusions are low salinity and HzO-CO2-CH 4 types. Inclusion fluids from quartz in ore yield homogenisation temperatures (T0 ranging from 298 ~ to 354~ (mean 320 ~ They are likely to have been trapped close to the solvus of the H20-COz-(CH4-NaC1 ) system and thus should give temperatures of the mineralising fluid. An additional, low T h population of later fluid inclusions is recognised in quartz from ore and syntectonic extension veins in the adjacent wallrock. Th'S for these low CO2-bearing inclusions range from 150 to 231~ (mean 190 c~C), and should be considerably lower than true trapping temperatures. Sulphur isotopic composition (~34S) of pyrite, sphalerite, pyrrhotite and galena ranges from 4.7 to 12.6%o and indicates a sulphur source from underlying Cobar Supergroup metasediments. An average temperature of 275 ~ from the sphalerite-galena sulphur isotopic thermometer suggests isotopic re-equilibration below peak metamorphic temperatures.

show abstract

Mass transfer and preferred orientation development during extensional microcracking in slate‐belt folds, Elura Mine, Australia

Cited by 12 publications

References 43 publications

Structural Control of Ore Deposits: The Role of Pre-Existing Structures on the Formation of Mineralised Vein Systems

Structural Control of Ore Deposits: The Role of Pre-Existing Structures on the Formation of Mineralised Vein Systems

Regional fluid and metal mobility in the Dalradian metamorphic belt, Southern Grampian Highlands, Scotland

Fluid inclusion and sulphur isotope evidence for syntectonic mineralisation at the Elura mine, southeastern Australia

Contact Info

Product

Resources

About