scholarly journals Mineralogical Constraints on the Potassic and Sodic-Calcic Hydrothermal Alteration and Vein-Type Mineralization of the Maronia Porphyry Cu-Mo ± Re ± Au Deposit in NE Greece

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 182 ◽  
Author(s):  
Vasilios Melfos ◽  
Panagiotis Voudouris ◽  
Margarita Melfou ◽  
Matías G. Sánchez ◽  
Lambrini Papadopoulou ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Fluid Phase ◽  
Aqueous Fluid ◽  
Gas Content ◽  
Magmatic Fluid ◽  
Brittle Deformation ◽  
Fluid Circulation ◽  
Magmatic Rocks ◽  
Vein Type ◽  
Host Rocks

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A- and B-type veins.

scholarly journals The Gersdorffite-Bismuthinite-Native Gold Association and the Skarn-Porphyry Mineralization in the Kamariza Mining District, Lavrion, Greece

Minerals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 531 ◽  
Author(s):  
Panagiotis Voudouris ◽  
Constantinos Mavrogonatos ◽  
Branko Rieck ◽  
Uwe Kolitsch ◽  
Paul Spry ◽  
...  
Keyword(s):  
Base Metal ◽  
Hydrothermal Fluid ◽  
Native Gold ◽  
Magmatic Fluid ◽  
Mining District ◽  
Sulfur Fugacity ◽  
Vein Type ◽  
Late Evolution ◽  
Initial Deposition ◽  
Host Rocks

Vein-type Pb-Ni-Bi-Au-Ag mineralization at the Clemence deposit in the Kamariza and “km3” in the Lavrion area, was synchronous with the intrusion of a Miocene granodiorite body and related felsic and mafic dikes and sills within marbles and schists in the footwall of (and within) the Western Cycladic detachment system. In the Serpieri deposit (Kamariza area), a porphyry-style pyrrhotite-arsenopyrite mineralized microgranitic dike is genetically related to a garnet-wollastonite bearing skarn characterized by a similar base metal and Ni (up to 219 ppm) enrichment. The Ni–Bi–Au association in the Clemence deposit consists of initial deposition of pyrite and arsenopyrite followed by an intergrowth of native gold-bismuthinite and oscillatory zoned gersdorffite. The zoning is related to variable As, Ni, and Fe contents, indicating fluctuations of arsenic and sulfur fugacity in the hydrothermal fluid. A late evolution towards higher sulfur fugacity in the mineralization is evident by the deposition of chalcopyrite, tennantite, enargite, and galena rimming gersdorffite. At the “km3” locality, Ni sulfides and sulfarsenides, vaesite, millerite, ullmannite, and polydymite, are enclosed in gersdorffite and/or galena. The gersdorffite is homogenous and contains less Fe (up to 2 wt.%) than that from the Clemence deposit (up to 9 wt.%). Bulk ore analyses of the Clemence ore reveal Au and Ag grades both exceeding 100 g/t, Pb and Zn > 1 wt.%, Ni up to 9700 ppm, Co up to 118 ppm, Sn > 100 ppm, and Bi > 2000 ppm. The “km3” mineralization is enriched in Mo (up to 36 ppm), Ni (>1 wt.%), and Co (up to 1290 ppm). Our data further support a magmatic contribution to the ore-forming fluids, although remobilization and leaching of metals from previous mineralization and/or host rocks, through the late involvement of non-magmatic fluid in the ore system, cannot be excluded.

Hydrothermal and Magmatic Fluid Flow in Asteroids

Asteroids IV ◽  
2015 ◽  
Author(s):  
L. Wilson ◽  
P. Bland ◽  
D. Buczkowski ◽  
K. Keil ◽  
A. N. Krot
Keyword(s):  
Fluid Flow ◽  
Magmatic Fluid

Perovskite, loparite and Ba-Fe hollandite from the Schryburt Lake carbonatite complex, northwestern Ontario, Canada

1994 ◽  
Vol 58 (390) ◽  
pp. 49-57 ◽  
Author(s):  
R. Garth Platt
Keyword(s):  
Fluid Phase ◽  
Ultramafic Rocks ◽  
Subsequent Reaction ◽  
Carbonatite Complex ◽  
Silicate System ◽  
Northwestern Ontario ◽  
Intimate Association ◽  
Free Mica ◽  
Host Rocks ◽  
Light Rare Earth Elements

AbstractWithin a suite of felsic-free, mica-rich alkaline ultramafic rocks of the Schryburt Lake carbonatite complex of northwestern Ontario, loparite and Ba-Fe hollandite occur in intimate association with perovskite. The host rocks have variable modal proportions of Mg-olivine, phlogopite, magnetite, ilmenite, apatite and carbonate (generally calcite) with minor Mg-salite. Thus, they correspond to ultramafic lamprophyres (i.e. aillikites), in the sense of Rock (1990) or the lamprophyric facies of the melilitite clan, in the sense of Mitchell (1993).Perovskite is the principal titanate phase, forming both euhedral and anhedral grains, the latter showing evidence of marginal resorption. It exhibits complex zonal patterns due principally to variations in the light rare earth elements, Na and Nb. In the nomenclature suggested, they may be termed perovskite and cerian perovskite. Loparite forms as small euhedral overgrowths on corroded perovskite cores. Chemically they are essentially solid solutions of loparite, lueshite and perovskite. Consequently, they may be termed calcian-loparite, calcian niobian loparite, niobian calcian loparite, loparite and niobian loparite. Titanates of the hollandite group are rare accessory minerals whose composition closely approach that of the septatitanate BaFe2+Ti7O16.The complex zoning of the perovskite grains has been attributed to the periodic introduction of carbonatite-derived fluids enriched in REE, Na and Nb into the silicate system during perovskite crystallization. Subsequent reaction of the early perovskite with F-bearing fluids leads to a localized environment enriched in Ti, Na, Nb and REE derived from both the fluid phase and the unstable perovskite. Loparite subsequently crystallizes from these micro-chemical environments.

scholarly journals Saline aqueous fluid circulation in mantle wedge inferred from olivine wetting properties

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yongsheng Huang ◽  
Takayuki Nakatani ◽  
Michihiko Nakamura ◽  
Catherine McCammon
Keyword(s):  
Fluid Transport ◽  
Mantle Wedge ◽  
Aqueous Fluid ◽  
High Electrical Conductivity ◽  
Interconnected Network ◽  
Fluid Circulation ◽  
Wetting Properties ◽  
Mantle Fluid ◽  
Conductivity Anomalies ◽  
Electrical Conductors

AbstractRecently, high electrical conductors have been detected beneath some fore-arcs and are believed to store voluminous slab-derived fluids. This implies that the for-arc mantle wedge is permeable for aqueous fluids. Here, we precisely determine the dihedral (wetting) angle in an olivine–NaCl–H2O system at fore-arc mantle conditions to assess the effect of salinity of subduction-zone fluids on the fluid connectivity. We find that NaCl significantly decreases the dihedral angle to below 60° in all investigated conditions at concentrations above 5 wt% and, importantly, even at 1 wt% at 2 GPa. Our results show that slab-released fluid forms an interconnected network at relatively shallow depths of ~80 km and can partly reach the fore-arc crust without causing wet-melting and serpentinization of the mantle. Fluid transport through this permeable window of mantle wedge accounts for the location of the high electrical conductivity anomalies detected in fore-arc regions.

Streaming Potential Induced by Canaliculi Fluid Flow: A Fluid-Filled Thick-Walled Cylinder Osteon Model Subjected to Axial Loading

2010 ◽  
Vol 34-35 ◽  
pp. 117-122
Author(s):  
Xiao Gang Wu ◽  
Wei Yi Chen
Keyword(s):  
Fluid Flow ◽  
Streaming Potential ◽  
Axial Loading ◽  
Fluid Phase ◽  
Form Solution ◽  
Solid Matrix ◽  
Intraosseous Pressure ◽  
Elastic Transverse ◽  
Close Form ◽  
Walled Cylinder

Based on the physiological structure of osteon, a single fluid-filled osteon model under only time-dependent axial loading is modeled for calculating the streaming potential induced by canaliculi fluid flow. Solid matrix is modeled as an elastic transverse isotropic thick-walled cylinder and fluid phase is considered as an incompressible Newtonian fluid. Close-form solution of the streaming potential for a single osteon model was obtained and used to study the electromechanical properties on intraosseous pressure and potential distribution. The solution can also be used as a benchmark for numerical studies of other osteon models.

Fracture-fluid relationships: implications for the sealing capacity of clay layers – Insights from field study of the Blue Clay formation, Maltese islands

2014 ◽  
Vol 185 (1) ◽  
pp. 51-63 ◽  
Author(s):  
Yves Missenard ◽  
Audrey Bertrand ◽  
Pierre Vergély ◽  
Antonio Benedicto ◽  
Marc-Edward Cushing ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Co2 Storage ◽  
Complex Deformation ◽  
Potential Host ◽  
Maltese Islands ◽  
Sealing Capacity ◽  
Fracture Fluid ◽  
Clay Layers ◽  
Clay Formation ◽  
Host Rocks

Abstract Sealing capacity of clay layers is a key parameter in many fields of geoscience, such as CO2 storage, hydrocarbons trapping, and waste disposal. In the context of deep geological disposal of radioactive waste, clayey formations are studied as potential host rocks. This work deals with tectonic fracturing, fluid flow, and the sealing capacity of clay layers in an outcropping formation sharing similarities to these potential host rocks. The Blue Clay formation (Maltese islands) outcrops between two limestones affected by slight extensional tectonics. Zones of oxidation around fractures are interpreted as evidence of palaeofluid circulation, and are used to assess the role of joints and faults in controlling the hydrological communication between adjacent layers. Joints and small faults (displacement < 5 m) seem to die out quickly up-section within the Blue Clays, and appear to have played an insignificant role in the palaeohydrology of the area. In contrast, large faults (displacement > 50 m) display clay smear structures, and the lack of oxidized zones around them suggests they served as barriers to fluid flow. Intermediate-sized faults die out up-section into complex deformation zones comprised of irregular joints that are filled with gypsum and surrounded by oxidation zones. These observations indicate that these intermediate-sized faults, usually considered as sealed by classical predictive methods such as “Shale Smear Factor”, may have played a significant role in the local palaeohydrology.

scholarly journals Metamorphic and Metasomatic Kyanite-Bearing Mineral Assemblages of Thassos Island (Rhodope, Greece)

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 252 ◽  
Author(s):  
Tarantola ◽  
Voudouris ◽  
Eglinger ◽  
Scheffer ◽  
Trebus ◽  
...  
Keyword(s):  
Crystal Size ◽  
Near Infrared ◽  
Coarse Grained ◽  
Fluid Circulation ◽  
Large Crystal ◽  
Northern Greece ◽  
Quartz Veins ◽  
Mineral Assemblages ◽  
Mineral Compositions ◽  
Host Rocks

The Trikorfo area (Thassos Island, Rhodope massif, Northern Greece) represents a unique mineralogical locality with Mn-rich minerals including kyanite, andalusite, garnet and epidote. Their vivid colors and large crystal size make them good indicators of gem-quality materials, although crystals found up to now are too fractured to be considered as marketable gems. The dominant lithology is represented by a garnet–kyanite–biotite–hematite–plagioclase ± staurolite ± sillimanite paragneiss. Thermodynamic Perple_X modeling indicates conditions of ca. 630–710 °C and 7.8–10.4 kbars. Post-metamorphic metasomatic silicate and calc-silicate (Mn-rich)-minerals are found within (i) green-red horizons with a mineralogical zonation from diopside, hornblende, epidote and grossular, (ii) mica schists containing spessartine, kyanite, andalusite and piemontite, and (iii) weakly deformed quartz-feldspar coarse-grained veins with kyanite at the interface with the metamorphic gneiss. The transition towards brittle conditions is shown by Alpine-type tension gashes, including spessartine–epidote–clinochlore–hornblende-quartz veins, cross-cutting the metamorphic foliation. Kyanite is of particular interest because it is present in the metamorphic paragenesis and locally in metasomatic assemblages with a large variety of colors (zoned blue to green/yellow-transparent and orange). Element analyses and UV-near infrared spectroscopy analyses indicate that the variation in color is due to a combination of Ti4+–Fe2+, Fe3+ and Mn3+ substitutions with Al3+. Structural and mineralogical observations point to a two-stage evolution of the Trikorfo area, where post-metamorphic hydrothermal fluid circulation lead locally to metasomatic reactions from ductile to brittle conditions during Miocene exhumation of the high-grade host-rocks. The large variety of mineral compositions and assemblages points to a local control of the mineralogy and fO2 conditions during metasomatic reactions and interactions between hydrothermal active fluids with surrounding rocks.

Sign in / Sign up

Export Citation Format

Share Document