The giant quartz-breccia veins of the Tyndrum–Dalmally area, Grampian Highlands, Scotland: their geometry, origin and relationship to the Cononish gold–silver deposit

2012 ◽  
Vol 103 (1) ◽  
pp. 51-76 ◽  
Author(s):  
P. W. Geoff Tanner
Keyword(s):  
Open Space ◽  
Fluid Pressure ◽  
Silver Deposit ◽  
Pore Fluid Pressure ◽  
Quartz Veins ◽  
Gold Silver ◽  
Coulomb Model ◽  
High Level ◽  
Transcurrent Faults ◽  
Cyclic Injection

ABSTRACTThe area lies within a ∼15 km-wide compartment of polyphase-deformed Dalradian (Neoproterozoic) rocks, bounded by the NE-trending Tyndrum and Ericht–Laidon transcurrent faults. Sinistral movement on these faults caused a periclinal structure, the Orchy Dome, to develop from flat-lying Dalradian rocks. This dome controlled the spatial distribution of lamprophyre intrusions and explosion breccia pipes, before being cross-cut by a network of near-vertical faults. Some of these faults are host to giant, segmented, quartz-breccia veins up to 5 km long and 19 m thick, formed by cyclic injection of over-pressured Si-rich fluid into newly-formed faults. The quartz-breccia bodies consist of a plexus of quartz veins with cockade and vuggy textures, indicative of open-space, high-level crystallisation. The faults comprise a NE-trending set of mineralised veins, including the Cononish Au–Ag deposit, and two pairs of conjugate [NW- and NE-trending] and [NNW- and NNE-trending], generally non-mineralised, faults. Their geometry is that predicted by the Coulomb model for Riedel R and R′ shear fractures, modified by variations in pore fluid pressure. They were active c. 430–425 Ma ago, coincident with emplacement of the Lochaber Batholith, whose buried extension, together with the mantle, probably provided the bulk of the fluid needed to form the veins.

Structural setting and timing of hydrothermal veins and breccias on Hurd Peninsula, South Shetland Islands: a possible volcanic-related epithermal system in deformed turbidites

1994 ◽  
Vol 131 (4) ◽  
pp. 465-483 ◽  
Author(s):  
Robert C. R. Willan
Keyword(s):  
Open Space ◽  
Hydrothermal Activity ◽  
South Shetland Islands ◽  
Shetland Islands ◽  
Quartz Veins ◽  
Intrusive Rocks ◽  
Extensional Faulting ◽  
High Level ◽  
The Antarctic ◽  
Main Vein

AbstractQuartz veins and vein-breccias in a greywacke-shale sequence of ?Carboniferous-Triassic age were previously regarded as mesothermal silicified fault breccias, and related to an adjacent Eocene granodiorite pluton. New mapping of vein assemblages and textures, and their structural and cross-cutting relationships, demonstrates that the steeply dipping, sheeted, epithermal-textured vein array was hydraulic in origin and possibly Cretaceous in age. The main vein and breccia swarm trends for 14 km NNE along-strike and 2 km across-strike, cutting large irregular areas of silicified and brecciated sandstone, and patchy areas of pyritic, propylitic and K-feldspar alteration. Angular vein fabrics and hydraulic disruption textures indicate wedging by hydrothermal solutions, hydraulic rupture, brecciation and fragment transport, followed by open-space precipitation, in veins generally < 15 cm thick and breccias up to a few metres thick. Hydrothermal quartz, chlorite, calcite and chalcedony predominate, with variable amounts of chalcopyrite, galena, sphalerite and pyrite. Epidote, arsenopyrite, K-feldspar and andradite garnet are conspicuous in places. Breccias were pre-and syn-mineralization, whereas mineral precipitation was pre-, syn- and post-breccia formation. Hydrothermal activity was simultaneous with extensional faulting, striking NNE, and accompanied by intrusion of dacitic dykes. There followed conjugate shearing on east- and ESE-striking faults, intrusion of high-level tonalite stocks, and several phases of basaltic andesite dyke intrusion. These hypabyssal rocks were probably coeval with the Antarctic Peninsula Volcanic Group dominating Livingston Island, dated between 130 and 75 Ma. Minor copper and iron sulphide-bearing veins occur in adjacent volcanic and hypabyssal intrusive rocks. The Hurd Peninsula veins may, therefore, form part of a volcanic-epithermal hydrothermal system (adularia-sericite-quartz type), of Cretaceous age, rather than a porphyry-related system of Eocene age.

Structural controls and origin of gold–silver mineralization in the Grampian Terrane of Scotland and Ireland

2014 ◽  
Vol 151 (6) ◽  
pp. 1072-1094 ◽  
Author(s):  
P. W. GEOFF TANNER
Keyword(s):  
Open Space ◽  
Hot Springs ◽  
Ground Surface ◽  
Maximum Principal Stress ◽  
Structural Controls ◽  
Quartz Veins ◽  
Dehydration Reactions ◽  
Gold Silver ◽  
Rhynie Chert ◽  
Fault Valve

AbstractGold-bearing mineral deposits occur over a strike distance of >300 km within the Grampian Terrane of Scotland and Ireland. This terrane consists of Neoproterozoic–Lower Ordovician rocks of the Dalradian Supergroup that were polyphase deformed and metamorphosed during the c. 470 Ma Grampian Orogeny. Sulphide-rich Au–Ag deposits occur in Scotland at Calliachar–Urlar Burn, Tombuie, Tyndrum and Cononish, and in Ireland at Curraghinalt (Omagh), Cavanacaw, Croagh Patrick, Cregganbaun and Bohaun. They are hosted by 0.1–6 m thick quartz veins and have a similar overall mineralogy, including native gold, As, Cu, Fe, Pb and Sn sulphides, with hessite, tetrahedrite and electrum present in the first six localities above. The mineralized quartz veins, which are characterized by open-space textures, crystallized at c. 3–5 km depth in the crust. All of the deposits were structurally controlled and, apart from Curraghinalt, occur within second-order Riedel R, R′ and T fractures resulting from a regional N–S-trending maximum principal stress. These deposits are of Upper Silurian to Lower Devonian (post-Scandian) age, and are inferred to have crystallized from hot, silica-rich metamorphic fluids derived from dehydration reactions at the greenschist/amphibolite-facies boundary. Curraghinalt is an older, Grampian, thrust-related deposit. Plutonic igneous rocks (mainly granitoid) contributed in part to the fluids, which were channelled into major orogen-parallel, strike-slip faults, to be injected by fault-valve pumping into the damage zones and fault breccias of newly formed Riedel fractures. Any residual fluid probably percolated to the ground surface to form Rhynie chert-type hot-springs.

scholarly journals Correction to: Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Kodai Nakagomi ◽  
Toshiko Terakawa ◽  
Satoshi Matsumoto ◽  
Shinichiro Horikawa
Keyword(s):  
Fluid Pressure ◽  
Pressure Control ◽  
Pore Fluid ◽  
2016 Kumamoto Earthquake ◽  
Pore Fluid Pressure ◽  
Seismicity Rate ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Seismicity Rate Changes

An amendment to this paper has been published and can be accessed via the original article.

scholarly journals Thermo-hydro-mechanical processes in fractured rock formations during a glacial advance

2015 ◽  
Vol 8 (7) ◽  
pp. 2167-2185 ◽  
Author(s):  
A. P. S. Selvadurai ◽  
A. P. Suvorov ◽  
P. A. Selvadurai
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fluid Pressure ◽  
Computational Modelling ◽  
Fracture Zones ◽  
Saturated Rock ◽  
Rock Formations ◽  
Geological Formation ◽  
High Level Nuclear Waste ◽  
High Level

Abstract. The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach that takes into account thermo-poroelasticity of the intact geological formation and the presence of a system of sessile but hydraulically interacting fractures (fracture zones). The modelling considers coupled thermo-hydro-mechanical effects in both the intact rock and the fracture zones due to contact normal stresses and fluid pressure at the base of the advancing glacier. Computational modelling provides an assessment of the role of fractures in modifying the pore pressure generation within the entire rock mass.

scholarly journals Mineragenic Position and Geological Potential of Technogenic- Mineral Formations of the Gold-Silver Deposit Valunistoe (Сhukotka Autonomous Region)

2021 ◽  
Vol 20 (2) ◽  
pp. 172-191
Author(s):  
V.N. Goldyrev ◽  
◽  
V.A. Naumov ◽  
O.B. Naumova ◽  
◽  
...  
Keyword(s):  
Industrial Development ◽  
Mineral Resources ◽  
Silver Deposit ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Chemical Parameters ◽  
Useful Components ◽  
Gold Silver ◽  
Solid Part ◽  
Physical And Chemical

In the coming years, the mine of LLC "Rudnik Valunisty" developing the gold and silver Valunistoe and Gornoye deposits will exhaust economically justified reserves. One of the ways to extend the life of the mine and increase the profitability of production should be the extraction of man-made secondary mineral resources. The purpose of the study is to identify the main types of solid and hydromineral form of technogenic-mineral formations at the Valunistoe Deposit, as well as to estimate the possibility of their industrial development. The useful components content was determined and calculated. The results of theoretical modeling of physical and chemical parameters of hypergenic mineral formation of the solid part of technogenic-mineral formations are shown. Objects of formation of technological waters are given. The conditions of concentration of gold and other metals are considered.

The Fluid-Solid Coupling Seepage Mathematical Model of Shale Gas

2013 ◽  
Vol 275-277 ◽  
pp. 598-602
Author(s):  
Wei Jun Shen ◽  
Xi Zhe Li ◽  
Jia Liang Lu ◽  
Xiao Hua Liu
Keyword(s):  
Mathematical Model ◽  
Shale Gas ◽  
Continuity Equation ◽  
Fluid Pressure ◽  
Seepage Flow ◽  
Stress Equation ◽  
Pore Fluid Pressure ◽  
Seepage Field ◽  
Fluid Coupling ◽  
Realistic Significance

In this paper, the stress equation is available by introducing the principle of effective stress in porous media into fluid-solid coupling seepage and considering the conditions of equilibrium. According to the continuity equation of fluid mechanics, considering the interactions between shale gas and rock-soil body, the differential equation of seepage flow is obtained. Through introducing the velocity component of rock particles into the seepage field, the pore fluid pressure in seepage field is introduced into the deformation field, so as to realize the interaction between the fluid-solid coupling seepage. Based on auxiliary boundary conditions in the above equations, the paper establishes the integrated fluid-coupling seepage mathematical model of shale gas, and it will provide the corresponding theoretical and realistic significance in the development of shale gas.

Age and Genesis of the Pokrovskoe Gold–Silver Deposit (Russian Far East)

2021 ◽  
Vol 62 (1) ◽  
pp. 134-143
Author(s):  
A.A. Sorokin ◽  
A.Yu. Kadashnikova ◽  
A.V. Ponomarchuk ◽  
A.V. Travin ◽  
V.A. Ponomarchuk
Keyword(s):  
Russian Far East ◽  
Far East ◽  
Volcanic Complex ◽  
Silver Deposit ◽  
Volcanic Zone ◽  
Granitoid Magmatism ◽  
Gold Silver ◽  
Igneous Complexes

Abstract ––We present results of geochronological studies of rocks from different igneous complexes and of hydrothermally altered volcanics with Au–Ag mineralization from the Pokrovskoe deposit. The age of the ore-hosting granites of the Sergeevsky pluton of the Upper Amur complex is estimated at ~129 Ma. The primary age of dacites of a sill-like body is within 128–125 Ma and is close to the age of volcanics of the Taldan complex. Propylitization processes superposed on these dacites are dated at ~122–119 Ma. Taking into account the commercial contents of gold and silver in these rocks, we believe that the age of the hosted orebodies is in the same interval. The period 122–119 Ma is also the time of formation of the Gal’ka volcanic complex in the Umlekan volcanic zone, which was accompanied by granitoid magmatism. This suggests that the formation of the Pokrovskoe deposit was associated with the accumulation of the Gal’ka complex.

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