fluid Inclusions Research Papers - Academia.edu (original) (raw)

The Mesoproterozoic Kaimur Group belonging to upper part of Vindhyan Supergroup, conformably overlies the carbonate sequence of Semri Group (Lower Vindhyan) in the Son Valley, central India. The Upper Kaimur Group consists of Dhandraul... more

The Mesoproterozoic Kaimur Group belonging to upper part of Vindhyan Supergroup, conformably overlies the carbonate sequence of Semri Group (Lower Vindhyan) in the Son Valley, central India. The Upper Kaimur Group consists of Dhandraul sandstone, Scarp sandstone and Bijaigarh shale. The detrital contents of the Dhandraul and Scarp sandstones are mainly composed of several varieties of quartz followed by feldspar, rock fragments, micas and heavy minerals. Fluid inclusion studies are carried out on the detrital and recrystallized quartz grains of the Dhandraul and Scarp sandstone to know about the fluid phases already present in the source rock and / or introduced in the recrystallisation process. Fluid micro-thermometry reveals the presence of two types of fluids: (i) bi-phase low saline aqueous inclusions, (ii) bi-phase high saline aqueous inclusion. These fluids were trapped during the development of grain and recrystallization processes. The salinity of these inclusions in the quartz grain is in the range of 5.7 to 13.4% suggests that initially there was good proportion of marine water during the initiation of sedimentation.

The world's largest mined rare-earth element deposits are associated with alkaline magmatism, making it important to understand the mechanisms leading to magmatic and hydrothermal element enrichment. We present results from... more

The world's largest mined rare-earth element deposits are associated with alkaline magmatism, making it important to understand the mechanisms leading to magmatic and hydrothermal element enrichment. We present results from late-differentiation-stage hydrothermal veins of the Jbel Boho alkaline complex in the district of Bou Azzer in the Anti-Atlas of Morocco, which show high light-REE enrichments. The REE mineralized veins occur around a syenitic pluton at the centre of the complex and consist of quartz-jasper and quartz veins which contain at least two silica generations. Only the second quartz generation is associated with LREE mineralization. The predominant REE-host mineral is the Ca-LREE-fluorcarbonate synchysite-(Ce), mainly present as anhedral crystals up to 200 μm. Some very small anhedral rhabdophane-(Ce) grains were also found in a synchysite-bearing quartz vein. Thermometric studies on mainly liquid-vapour-solid fluid inclusions in quartz crystals in the synchysite-bearing veins suggest very high salinity (32 to 37 wt% NaCl equiv.) of the mineralizing fluid. Homogenization temperatures from 150° to 250 °C provide the minimum temperature conditions in which the quartz veins were formed.
Based on recent experimental data, we propose a model for the formation of hydrothermal REE-Ca-F carbonate deposits in the veins, involving the transport of REE as chloride complexes at low pH conditions in the presence of fluoride ions. The deposition of synchysite is proposed to result from neutralization of this fluid by mixing of hydrothermal ore fluids with carbonate-rich meteoric water or by interaction with already existing carbonates in the vein, As well as raising the pH, this interaction also provides the Ca+ and CO32– ions needed for REE precipitation as Ca-F carbonates.
The barren veins show two types of mineralogy and REE patterns: quartz-carbonate veins with enrichment of LREE over HREE and iron-rich jasper-bearing veins with quite flat REE pattern and high HREE. The LREE/HREE fractionation in these veins seems to be controlled by an interplay of two factors: 1) a low activity of ligands like Cl, which favours LREE transport and (2) the mineralogical control, by which HREE having similar ionic radii to Fe2 + will be preferred over LREE.

BSTRACT The Cenozoic Urumieh-DokhtarMagmaticBelt (UDMB) of Iran is a major host to porphyry Cu-Mo-Au deposits (PCDs),represented by the world-class Sarcheshmeh deposit and Miduk deposit in the south and the Sungun deposit in the north.... more

BSTRACT
The Cenozoic Urumieh-DokhtarMagmaticBelt (UDMB) of
Iran is a major host to porphyry Cu-Mo-Au deposits (PCDs),represented by the world-class Sarcheshmeh deposit and Miduk deposit in the south and the Sungun deposit in the north. Vein type, base and/or precious metal deposits are also common and
some are spatially associated with PCDs. Latala and Chahmessi
are vein type, base and precious metal deposits in the north and southwest Miduk deposit. The area is covered mainly by PaleoceneEocene volcanic and pyroclastic rocks of basaltic, basaltic-andesitic and trachy-andesitic compositions, and minor marls and limestones.
The volcanic and pyroclastic rocks are intruded by Miocene shallow intrusions of quartz diorite, quartz monzonite and granodiorite compositions.The rocks are host to a set of ore-bearing quartz veins.
Mineralization in both the Chahmessi and Latala deposits are controlled by faults and fractures. The role of the ring structures and faults in the distribution of hydrothermal alteration zones and
mineralization is important in the Latala deposit. In these veins,euhedral quartz with sulfide mineralization occurs as open space fillings, minor replacement bodies and hydrothermal breccia. The veins consist of quartz, calcite, pyrite, chalcopyrite, galena, sphalerite, bornite and minor sulfosalts, particularly enargite.
According to studies based on fluid inclusions in the Miduk porphyry, three types of fluids are responsible for mineralization.
Homogenization temperatures and salinity in porphyry-type fluids vary from 566 to 162 °C and 61.3 to 1.2 wt% NaCl equiv. For the Latala vein type base and precious metals deposit, homogenization temperature and salinity vary from 380 to 131 °C and 10.6 to 0.17
wt% NaCl equiv. The gas phase in fluid inclusions of Latala is dominated by CO2 but also shows the presence of CO and H2, characterizing reducing conditions associated with ore deposition.
The change from lithostatic to hydrostatic regime, boiling and fluid
dilution associated with the introduction of meteoric fluids provides an explanation for the widespread Th and salinity data. Calculated pressure for examples of Miduk fluid inclusions varies from 700 to 200 bars. These pressures correspond to depths of 2500 to 1500
metres for porphyry mineralization. The three-phase fluid
inclusions, corresponding to magmatic fluid, show the highest pressure. The Latala base and precious metals deposit has formed at pressures between 200 and 100 bars, corresponding to a depth of less than 1 km. Sphalerite mineralization occurs in shallow
parts of the sedimentary-volcanic sequence from magmatic fluids diluted by meteoric fluids and also occurs in more distal parts of the porphyry. The sulphur isotopic composition for sulfide minerals
varies between -9.8 and -1.0‰, which correspond to values of magmatic sulfur. This suggests that magmatic water was responsible for transportation of metals in Latala. Epithermal mineral precipitation occurred upon dilution of the low-salinity magmatic fluid with meteoric water, which entered thehydrothermal system as it cooled and successively diluted during continued magmatic fluid ascent.

Ore deposits: Mt Isa Inlier

Fluid inclusions are small volumes of paleofluid trapped in minerals which provide indispensable information about geological processes, from high temperatures at depth towards low temperatures near the Earth’s surface. The... more

Fluid inclusions are small volumes of paleofluid trapped in minerals which provide indispensable information about geological processes, from high temperatures at depth towards low temperatures near the Earth’s surface. The inclusions are trapped gases, liquids or crystals, either trapped singularly (one-phase) or as a heterogeneous mixture of more than one phase (multi-phase) in a single cavity. Depending upon the timing of entrapment of liquid in the crystals, fluids are classified as primary, secondary or pseudosecondary. The inclusions occur either isolated, clustered, or trail bound; those occurring in groups form the Group of Synchronous Inclusions (GSI) having similar composition and time of entrapment. The composition of trapped fluid varies greatly; commonly detected constituents include H2O, CO2, CH2, H2S, Cl, Br, F, I, N2, S, Na, K, Ca, Mg and Fe. There are several instruments used in the study of fluid inclusions, but the basic study is carried out using heatingfreezing stages and Laser Raman Microprobe. The study of f luid inclusions reveal geologically important information such as temperature, pressure, salinity, density and depth of trapping; and thereby provide direct information about the conditions at which given minerals and rocks are formed.

Over the last 25 years, the gem industry has seen an increasing number of reports by associates and laboratories indicating a tremendous proliferation of synthetic quartz at all levels of the market. The stones reported were most often of... more

Over the last 25 years, the gem industry has seen an increasing number of reports by associates and laboratories indicating a tremendous proliferation of synthetic quartz at all levels of the market. The stones reported were most often of the finest colors and with excellent clarity, often eye-clean. In recent years, there has been more material seen in colors without a natural counterpart.

Ali Javad porphyry copper-gold deposit is located in Arasbaran porphyry copper belt at northwestern Iran, some 20 km east of Sungun Mine. Porphyry mineralization at the Ali Javad deposit occurred in post-Oligocene quartz monzonite bodies... more

Ali Javad porphyry copper-gold deposit is located in Arasbaran porphyry copper belt at northwestern Iran, some 20 km east of Sungun Mine. Porphyry mineralization at the Ali Javad deposit occurred in post-Oligocene quartz monzonite bodies which intruded in the Eocene volcanic rocks. Mineralization occurred as veins, veinlets and dissemination both as hypogene and supergene type. Several types of veinlets were distinguished during the study of the deposit. Fluid inclusion studies on fluids trapped in quartz which were taken from drill core samples indicated a wide range of homogenization temperature in the veinlets from 138˚C to 565˚C which their salinity demonstrated 33-61 wt% NaCl equivalent. Mineralizing fluids density at the deposit was 0.8-1.2 g/cm 3. Fluid inclusion studies suggested that Ali Javad deposit is an Au-rich porphyry copper deposit ; its fluid inclusion features were comparable with other porphyry deposits.

The Gushfil stratabound Zn-Pb-(Ag-Ba) deposit is hosted by an Early Cretaceous siliciclastic-carbonate sequence deposited in an extensional back-arc basin setting in the Malayer-Esfahan Metallogenic Belt in the southern part of the... more

The Gushfil stratabound Zn-Pb-(Ag-Ba) deposit is hosted by an Early Cretaceous siliciclastic-carbonate sequence deposited
in an extensional back-arc basin setting in the Malayer-Esfahan Metallogenic Belt in the southern part of the Sanandaj-Sirjan
Zone, Iran. Mineralization is mainly hosted in dolostone and black siltstone. Based on petrographic studies there are three sulphide
ore facies: feeder zone, bedded and massive. Textures observed within these styles are semi-massive, massive, framboidal, colloform,
laminated and vein-veinlet. Sulphide minerals are predominantly sphalerite, galena, tetrahedrite, chalcopyrite and pyrite,
with lesser bornite. Barite, dolomite and quartz are major non-sulphide gangue minerals. Based on microscopic studies, sulphide
mineralization in the Gushfil deposit was emplaced in two stages: stage I (pre-ore) is comprised of barite and fine-grained, framboidal,
colloform and laminated pyrite and minor sphalerite and galena, and stage II (main) comprises coarse-grained, semi-massive
to massive, and vein/veinlet sphalerite, galena, tetrahedrite, chalcopyrite, pyrite and lesser bornite. Dolomitization, silicification
and sericitization are the major hydrothermal alteration styles in the Gushfil deposit, and they occur in all host rocks, but only in
the immediate vicinity of the Gushfil-Baghabrisham syn-sedimentary normal fault (GBF) that served as the main conduit for the
mineralizing fluids. High contents of redox sensitive elements such as Mo, V, and, U in the black siltstone host rocks indicate that
mineralization formed in an anoxic ambient environment. The enrichment of LREE compared to HREE (high ration of LaN/YbN)
and the ƩREE content of dolomitized limestone host rocks of the Gushfil deposit indicate inter action of hydrothermal fluids with
marine limestone. The host rocks lack Ce anomalies, in marked contrast to the mostly negative Ce anomalies of oxic seawater, also
indicating deposition under reduced conditions for the siltstones and a reduced hydrothermal fluid overprint on the dolostone host
rocks that occurred concomitantly with ore deposition.
Sphalerite from the feeder zone have 160 to 239 °C trapping temperature with salinities ranging from 8.7 to 23.3 eq. wt.% NaCl
whereas, those of sphalerite from the massive ore ranges from 125 to 220 °C, with salinities ranging from 16.8 to > 23.3 eq. wt.%
NaCl. The data suggest that ore fluid temperatures decreased with increasing distance from the feeder zone (in the GBF) and toward
massive ore. Abundant pyrite framboids, interlaminated organic matter (bitumen) with sulphide minerals, and negative sulphur isotope
values of sulphides collectively indicate that sulphur was sourced from bacterially reduced seawater sulphate. Sulphide minerals
precipitated due to mixing of this fluid with metal-bearing higher temperature hydrothermal fluid. Collectively, the host rocks,
structural setting, ore styles (bedded, feeder zone, and massive), mineralogy, textures, and fluid inclusion micro-thermometric data
indicate that Gushfil is a SEDEX-type deposit in which sulphide minerals were formed below the seafloor during sedimentation
through early diagenesis.

The Late Paleozoic Kairagach epithermal gold deposit belongs to the high-sulfidation (acid–sulfate) type. It is located at the northern slope of the Kuramin Ridge in the central Tien Shan, 3.5 km northwest of the Kochbulak deposit, being... more

The Late Paleozoic Kairagach epithermal gold deposit belongs to the high-sulfidation (acid–sulfate) type. It is located at the northern slope of the Kuramin Ridge in the central Tien Shan, 3.5 km northwest of the Kochbulak deposit, being confined to the volcanic andesite–dacite sequence (C2–3) composing the northeastern segment of the Karatash caldera. Volcanogenic sequences are intruded by subvolcanic dacite–porphyry and diorite–porphyry intrusions, as well as granodiorite–porphyry and porphyritic diabase dikes of the northeastern strike. The gold–sulfide–selenide–telluride mineralization of the Diabazovaya zone, which encloses the main gold resources, associates with these dikes. Unlike typical epithermal deposits of the high-sulfidation type with Au–Cu geochemical specialization of ores, the Kairagach deposit is characterized by distinct Au–Sn–Bi–Se–Te mineralization, which includes over 80 ore minerals, including new and rare ones. This paper discusses data on the geological structure of the deposit, ore geochemistry, variations in chemical composition, mode of occurrence and parageneses of native elements (Au, Ag, Te, Sn, Bi); sulfides of Fe, Cu, Pb, Zn, and Ag; fahlores of the tetrahedrite–tennantite–annivite–goldfieldite series; bismuthinite–aikinite, junoite, and pavonite sulfosalts; Cu and Fe sulfostannate; various Au, Ag, Pb, Fe, Hg, Bi, and Sb tellurides and Bi sulfoselenides; and Fe and Sn oxides. The chemical composition of ordinary, high-grade, and bonanza ores and the vertical and lateral (including hidden) mineralization zoning, as well as the succession of mineral parageneses, P–T parameters, composition of mineral-forming fluids, and main factors and mechanisms responsible for the formation of goldproductive mineral associations, are considered. The variations in the S, C, O, and H compositions of ore minerals are used to define probable sources of water and ore components in ore-forming fluids. The results of thermodynamic modeling of probable gold occurrence and transportation in the mineral-forming solution are also discussed.

Instrumental Analyses in Economic Geology-Fluid Inclusion

The Arak basin in the northern part of the Malayer-Esfahan metallogenic belt (MEMB) of Iran hosts 9 Zn-Pb sulfide deposits within a Jurassic sedimentary succession of black, fine-grained sandstone, siltstone and shale. This succession was... more

The Arak basin in the northern part of the Malayer-Esfahan metallogenic belt (MEMB) of Iran hosts 9 Zn-Pb sulfide deposits within a Jurassic sedimentary succession of black, fine-grained sandstone, siltstone and shale. This succession was deposited in an extensional back-arc environment between the Sanandaj- Sirjan Zone (SSZ) and the Central Iranian microcontinent. Two of the 9 deposits (Western Haft-Savaran and Hossein-Abad) are the focus of study. Here, three ore facies can be distinguished, based on the morphology of the orebodies and the sulfide mineralogy and textures: (a) stockwork, (b) massive, and (c) bedded mineralization. The stockwork and massive mineralization are interpreted to have formed in the subsurface, whereas bedded mineralization was sedimented on the seafloor. The Fe contents of sphalerites from massive and stockwork mineralization from the two deposits, together with the presence of pyrrhotite inclusions, indicate that sphalerite precipitated from relatively low fS 2 (< 10 −11 ) fluid. Homogenization temperatures of fluid inclusions in sphalerite, quartz and siderite in massive mineralization range from 105 to 309 °C, and average 208 °C, with salinities between 4.03 and 11.1 wt% NaCl eq., and averaging 5.77 wt% NaCl eq. These widely ranging salinities and homogenization temperatures reflect mixing of shallow connate water with venting metalliferous fluid that is of deep basinal origin, and deposition of mineralization predominantly below the seafloor. Collectively, the host rock types, ore facies and textures, deposition in an reduced ambient environment, fluid inclusion temperatures and salinities, and mineralizing fluid behaviour at the seafloor are all compatible with a vent-proximal sedimentary exhalative (SEDEX) origin for the Western Haft-Savaran and Hossein-Abad deposits.

Mineralized NYF and LCT pegmatites occur throughout the northeast-trending Neoproterozoic Damara Belt, Namibia. Mineralization in the pegmatites varies geographically, from the northeast, where they are enriched in Li-Be, to the... more

Mineralized NYF and LCT pegmatites occur throughout the northeast-trending Neoproterozoic Damara Belt, Namibia. Mineralization in the pegmatites varies geographically, from the northeast, where they are enriched in Li-Be, to the southwest, where they also contain notable Sn and U. Similar fluid inclusion populations occur throughout the pegmatites, regardless of their respective metal enrichments, and primary fluid inclusion textures were destroyed by continued fluid activity. Pseudosecondary to secondary inclusions are aqueo-carbonic, carbonic, and aqueous in composition, and have been divided into five types. The earliest populations are saline (>26.3 eq. wt.% NaCl), homogenizing at temperatures in excess of 300 °C. Their carbonic phase is composed of CO 2 , with minor CH 4 , and micro-elemental mapping indicates they contain trace metals, including Ca, Fe, Zn, Cu, and K. Type 3 inclusions formed later, homogenize at ~325 °C, and are less saline, with a carbonic phase composed of CO 2. Type 4 carbonic inclusions are composed of pure CO 2 , and represent the latest stages of fluid evolution, while Type 5 aqueous inclusions are believed to be unrelated to the crystallization of the pegmatites, and rather the result of regional Cretaceous magmatism, or the ingress of meteoric water. The similarities in fluid inclusion populations observed in the pegmatites suggest that differences in mineralization were driven by magma composition rather than fluid activity alone, however saline fluids facilitated the enrichment and deposition of metals during the late stages of crystallization. Furthermore, the similarities between fluid inclusion populations in different pegmatites suggests they share a similar fluid evolution.

Dazhuangzi gold deposit lies in Pingdu city, Shandong province, China. Tectonically, it is located at the southwestern border of Jiaobei terrain, across which is the Mesozoic Jiaolai basin, and to the west, it is adjacent to the Yishu... more

Dazhuangzi gold deposit lies in Pingdu city, Shandong province, China. Tectonically, it is located at the southwestern border of Jiaobei terrain, across which is the Mesozoic Jiaolai basin, and to the west, it is adjacent to the Yishu fault zone. The ore bodies, which were hosted in metamorphic rocks of Paleoproterozoic Jingshan Group, can be divided into two types, namely the “altered cataclasite or mylonite type” and “quartz vein type”. Microthermometric investigation reveals that gold precipitation occurred at 240~280℃ from CO2-rich, low salinity (7~8wt.%NaCl) hydrothermal fluids in which there were no other volatiles except H2O and CO2. More importantly, phase separation is recognized and firmly believed to be responsible for the main stage mineralization. Results of hydrogen and oxygen isotope study suggest that ore-forming fluids were a mixture of magmatic water, which might have originated from degassing of mafic magmas deep underneath the region, and meteoric water. Sulfur isotope study demonstrates that sulfides have a δ34S value range of 7.9~11.3‰, which is quite similar to that of metamorphic rocks of Jingshan Group, thus indicating that sulfur in the ore-forming fluids was dominantly derived from the metamorphic rocks of Jingshan Group.

Freezing-point depression was measured in aqueous fluid inclusions to determine salinities in six samples of jadeitite and jadeite-rich rock from the Jagua Clara serpentinite mélange of the Rio San Juan Complex, Dominican Republic. The... more

Freezing-point depression was measured in aqueous fluid inclusions to determine salinities in six samples of jadeitite and jadeite-rich rock from the Jagua Clara serpentinite mélange of the Rio San Juan Complex, Dominican Republic. The mélange represents a fossil subduction-zone channel from a cold, mature subduction zone with a geothermal gradient of ~6 °C/km. One hundred and twenty-five determinations of salinity in primary inclusions hosted in jadeite, quartz, apatite and lawsonite range between extremes of 1.2 and 8.7, but yield a well-defined mean of 4.5 ± 1.1 wt% (±1 s.d.) NaCl equiv, slightly higher than mean seawater (3.5 wt%). In one sample, eight additional fluid inclusions in quartz aligned along grain boundaries yield slightly lower values of 2.7 ± 1.3 wt% NaCl equiv. Homogenization temperatures were also measured for 47 fluid inclusions in two samples , but primary entrapment densities are not preserved. It is significant that the suite includes two types of samples: those precipitated directly from an aqueous fluid as well as examples of metasomatic replacement of a pre-existing magmatic rock. Nevertheless, the results indicate identical salinity for both types and suggest a much stronger genetic link between the two types of jadeitite and jadeite-rich rock than has previously been assumed. Based on the results of conductivity measurements in modern subduction zones, we envision a pervasive fluid in the subduction channel that evolved from salinity levels lower than those in seawater up to the measured values due to ongoing but largely completed serpentinization in the subduction channel. The present data represent a reference marker for the subduction channel of the Rio San Juan intra-oceanic subduction zone at 30–50 km depth and after 50–60 Myr of operation.

The Lamego orogenic gold deposit (440,742oz gold measured reserves and 2.4milliont measured resources, with an average grade of 5.71g/t Au and a cut-off grade of 2.15g/t Au; AngloGold Ashanti Córrego do Sítio Mineração S/A (AGA) personal... more

The Lamego orogenic gold deposit (440,742oz gold measured reserves and 2.4milliont measured resources, with an average grade of 5.71g/t Au and a cut-off grade of 2.15g/t Au; AngloGold Ashanti Córrego do Sítio Mineração S/A (AGA) personal communication, 2014) is located in the 5km-long trend that includes the world-class Cuiabá deposit. It is hosted in the Neoarchean metavolcano–sedimentary rocks of the Rio das Velhas greenstone belt, Quadrilátero Ferrífero, Brazil. Mineralization is associated mainly with metachert–banded iron formation (BIF) and carbonaceous phyllites in the reclined Lamego fold, in which the Cabeça de Pedra orebody represents the hinge zone. Mineralization is concentrated in silicification zones and their quartz veins, as well as in sulfide minerals, product of BIF sulfidation. Hydrothermal alteration varies according to host rock, with abundant sulfide–carbonate in BIF, and sericite–chlorite in carbonaceous phyllite. Quartz vein classification according to structural relationships and host rocks identified three vein systems. The V1 system, mainly composed of smoky quartz (Qtz I) and pyrite, is extensional, crosscuts the bedding plane S0 of BIF, and is parallel to the fold axis. The V2 system, of the same composition, is represented by veins that are parallel to the S1–2 foliation and S0. This system is also characterized by silicification zones in the BIF–carbonaceous phyllite contact that has its maximum expression in the hinge zone of folds. The V3 system has milky quartz (Qtz II) veins, which result from the recrystallization of smoky quartz, located mainly in shear zones and faults; these veins form structures en echelon and vein arrays. The most common ore minerals are pyrite, As-pyrite and arsenopyrite. Fluid inclusion-FI trapped in all quartz veins present composition in the H2O–CO2 ±CH4–NaCl system. Fluid evolution can be interpreted in two stages: i) aqueous–carbonic fluid trapped in Qtz I, of low salinity (~2% equiv. wt.% NaCl), and ii) carbonic–aqueous fluid, of moderate salinity (average 9eq.wt.% NaCl) hosted in Qtz II. Both stages are characterized by decrepitation temperatures in the range of 200 to >300°C, and suggest a fluid of metamorphic origin. Applying an arsenopyrite geothermometer, the calculated formation temperature for the Cabeça de Pedra orebody is 300 to 375°C. The vertical intersection of the isochors allows a minimum pressure calculation of 2.6kbar. The composition of individual FIs of this orebody, obtained by LA-ICP-MS analyses, compared with results of FIs for the Carvoaria Velha deposit, Córrego do Sítio lineament, highlights a standard composition typical of metamorphic fluids with Na>K>Ca>Mg, which increase or decrease in concentration as a function of salinity in both deposits. Trace elements vary according to fluid–rock reactions, and are directly related to the host rock composition. The comparison of data sets of the two deposits shows that the Cabeça de Pedra FIs have a higher enrichment in Zn, while Cu, As and Sb are richer in Carvoaria Velha, suggesting influence of the host rock geochemistry. The suggested mechanisms for gold precipitation at the Cabeça de Pedra orebody, Lamego gold deposit are: i) hydrolysis of the carbonaceous matter of phyllite and BIF, affecting fO2, destabilizing sulfur complexes and enhancing gold precipitation; ii) replacement of BIF iron carbonates by sulfides; and iii) continuous pressure changes that lead to silica precipitation and free gold. Other than playing the long-recognized role of the carbonaceous phyllites as a fluid barrier, the data highlight their importance as a source of metals.

The Mergui Belt of Myanmar is endowed with several important orogenic gold deposits, which have economic significance and exploration potential. The present research is focused on two gold districts, Modi Taung-Nankwe and Kyaikhto in the... more

The Mergui Belt of Myanmar is endowed with several important orogenic gold deposits, which have economic significance and exploration potential. The present research is focused on two gold districts, Modi Taung-Nankwe and Kyaikhto in the Mergui Belt comparing their geological setting, ore and alteration mineralogy, fluid inclusion characteristics, and ore-forming processes. Both of the gold districts show similarities in nature and characteristics of gold-bearing quartz veins occurring as sheeted veins, massive veins, stockworks to spider veinlets. These gold deposits are mainly hosted by the mudstone, slaty mudstone, greywacke sandstone, slate, and slaty phyllite of Mergui Group (dominantly of Carboniferous age). The gold-bearing quartz veins generally trend from NNE to N-S, whereas some veins strike NW-SE in all deposits. The gold-bearing quartz veins are mainly occurred within the faults and shear zones throughout the two gold districts. Wall-rock alterations at Shwetagun are mainly silicification, chloritization, and sericitization, whereas in Kyaikhto, silicification, carbonation, as well as chloritization, and sericitization are common. At Shwetagun, the gold occurred as electrum grains in fractures within the veins and sulfides. In Kyaikhto, the quartz-carbonate-sulfide and quartz-sulfide veins appeared to have formed from multiple episodes of gold formation categorizing mainly as free native gold grains in fractures within the veins or invisible native gold and electrum within sulfides. At Shwetagun, the ore minerals in the auriferous quartz veins include pyrite, galena, and sphalerite, with a lesser amount of electrum, chalcopyrite, arsenopyrite, chlorite, and sericite. In Kyaikhto, the common mineralogy associated with gold mineralization is pyrite, chalcopyrite, sphalerite, galena, pyrrhotite, arsenopyrite, marcasite, magnetite, hematite, ankerite, calcite, chlorite, epidote, albite, and sericite.

The Bou Dahar Pb–Zn–Ba (±Sr) is hosted in the Lower and Middle Liassic carbonate platform in the oriental High Atlas of Morocco. The paragenetic sequence includes quartz–pyrite–melnicovite–sphalerite–galena– calcite–barite ± fluorite– ±... more

The Bou Dahar Pb–Zn–Ba (±Sr) is hosted in the Lower and Middle Liassic carbonate platform in the oriental High Atlas of Morocco. The paragenetic sequence includes quartz–pyrite–melnicovite–sphalerite–galena– calcite–barite ± fluorite– ± celestite. Fluid-inclusion studies were conducted on sphalerite (early mineralizing stage) and barite, and celestite (late mineralizing stage). These studies reveal two end-member fluids, a hot (~143 °C) and saline fluid (~23 wt.% NaCl eq.) and a cooler (b50 °C) and diluted fluid (~5 wt.% NaCl eq.). Based on fluid-inclusion and C–O–S isotope studies, a conclusion is reached that the Bou Dahar ore deposits were formed by the mixing of two fluid — a diluted, SO2−4-rich fluid, and an 18O-enriched basinal brine that car- ried Pb, Zn, and Ba. The sulfur required for the precipitation of sulfides was generated by the thermochemical sul- fate reduction of dissolved sulfate (SO24−) of the Mesozoic seawaters, and delivered to the site of ore deposition. The sulfur of sulfate minerals was derived directly from these dissolved SO24. The Pb isotope compositions are ho- mogenous with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios ranging from 18.124 to 18.183, 15.630 to 15.634, and 38.325 to 38.440 respectively. This Pb isotope composition is indicative of an upper crust and orogene reser- voirs as the source of lead and other metals. The emplacement of mineralization occurred during the Eocene– Miocene Alpine orogeny, and tectonic burial and compression were the driving forces behind the circulation of the orogenic-brines. These ore-forming fluids migrated, along thrusting regional E–W and NE–SW deep-seated faults, to the confined carbonate-Liassic reservoir.

Ore deposits: Orogenic gold

The origin of salinity in crustal fluids can be deduced from their Cl, Br and Na concentrations and associated Cl/Br and Na/Br ratios. Here, a protocol for quantitative analysis of Cl, Br and Na concentration in individual fluid... more

The origin of salinity in crustal fluids can be deduced from their Cl, Br and Na concentrations and associated Cl/Br and Na/Br ratios. Here, a protocol for quantitative analysis of Cl, Br and Na concentration in individual fluid inclusions of variable size, bulk salinity, Cl, Br and Na contents is presented. It combines microthermometry and laser ablation — inductively coupled plasma mass spectrometry (LA-ICPMS) analysis.The method is based on: (i) microthermometric measurement of ice melting, hydrate melting, halite dissolution and sylvite dissolution temperatures in fluid inclusions; (ii) calibration of LA-ICPMS signals of Br by analyzing Na–Br–Cl standard solutions loaded in silica glass capillaries; (iii) calculation of solute (Cl, Na, Ca, K, Mg) concentration based on LA-ICPMS intensities and the Pitzer thermodynamic model (for inclusions of salinity below 23 wt.% equivalent NaCl), or a charge-balance approach (for higher salinity inclusions) and (iv) calculation of uncertainty on Cl, Br and Na concentration and Cl/Br and Na/Br ratios in the fluid.This method is applied to natural fluid inclusions with variable Cl, Br and Na contents as previously determined by microthermometry and bulk crush-leach coupled with ion chromatography analysis. The studied materials consist of: i) low-salinity inclusions from Alpine quartz veins and ii) high-salinity inclusions from the Trimouns talc deposit and from Athabasca Basin uranium deposits. Molar Cl/Br and Na/Br ratios range from 140 ± 50 to 1200 ± 400 and 17 ± 6 to 880 ± 290 in the analyzed inclusions. The calculated uncertainty on Cl/Br and Na/Br ratios in individual fluid inclusions is between 30 and 38%, regardless of the salinity. It appears that the analysis of individual inclusions coupled with uncertainty calculation allows the identification of significant variation of Cl/Br and Na/Br ratios within individual samples that could not be identified from previous bulk crush-leach and ion chromatography analyses. Because Br is a minor solute (molar Cl/Br is between ~ 100 and ~ 10000 in most crustal fluids), and because of its high first ionization energy, the determination of Br concentration in individual inclusion by combining microthermometry and LA-ICPMS analysis is most readily achievable for large (> 50 μm in diameter) inclusions. For smaller inclusions (10 to 50 μm in diameter), the applicability of the present method is more sensitive to the Br concentration.

Abstract —Melt and fluid inclusions were investigated in minerals from igneous rocks and ore (Au–Ag–Pb–Zn) veins of the Stiavnica ore field in Central Slovakia. High H2O (7.1–12.0 wt %) and Cl (0.32–0.46 wt %) contents were found in... more

Abstract
—Melt and fluid inclusions were investigated in minerals from igneous rocks and ore (Au–Ag–Pb–Zn) veins of the Stiavnica ore field in Central Slovakia. High H2O
(7.1–12.0 wt %) and Cl (0.32–0.46 wt %) contents
were found in silicate melt inclusions (65–69 wt % SiO2 and 5.2–5.6 wt % K2O ) in plagioclase phenocrysts
(
An
68–36) from biotite–hornblende andesites of the eastern part of the caldera. Similar high water contents are
characteristic of magmatic melts (71–76 wt %
SiO
2
and 3.7–5.1 wt %
K
2
O
) forming the sanidine rhyolites of
the Vyhne extrusive dome in the northwestern part of the Stiavnica caldera (up to 7.1 wt %) and the rhyolites
of the Klotilda dike in the eastern part of the ore field (up to 11.5 wt %). The examination of primary inclusions
in quartz and sanidine from the Vyhne rhyolites revealed high concentrations of
N
2
and
CO
2
in magmatic fluid
(8.6 g/kg
H
2
O
and 59 g/kg
H
2
O
, respectively). Fluid pressure was estimated as 5.0 kbar on the basis of primary
CO
2
fluid inclusions in plagioclase phenocrysts from the Kalvari basanites. This value corresponds to a depth
of 18 km and may be indicative of a deep CO
2
source. Quartz from the granodiorites of the central part of the
Stiavnica–Hodrusa complex crystallized from a melt with 4.2–6.1 wt % H
2
O and 0.24–0.80 wt % Cl. Magmatic
fluid cogenetic with this silicate melt was represented by a chloride brine with a salinity of no less than 77–
80 wt % NaCl equiv. Secondary inclusions in quartz of the igneous rocks recorded a continuous trend of temperature,
pressure, and solution salinity, from the parameters of magmatic fluids to the conditions of formation
of ore veins. The gold mineralization of the Svyatozar vein system was formed from boiling low-salinity fluids
(0.3–8.0 wt % NaCl equv.) at temperatures of 365–160
°
C and pressures of 160–60 bar. The Terezia, Bieber,
Viliam, Spitaler, and Rozalia epithermal gold–silver–base metal veins were also formed from heterogeneous
low-salinity fluids (0.3–12.1 wt %) at temperatures of 380–58
°
C and pressures of 240–10 bar. It was found that
the salt components of the solutions were dominated by chlorides (high content of fluorine, up to 0.45 mol/kg
H
2
O
, was also detected), and sulfate solutions appeared in the upper levels. The dissolved gas of ore-forming
solutions was dominated by
CO
2
(0.1–8.4 mol %, averaging 1.3 wt %) and contained minor nitrogen (0.00–
0.85 mol %, averaging 0.05 mol %) and negligible methane admixtures (0.00–0.05 mol %, averaging
0.004 mol %). These data allowed us to conclude that the magmatic melts could be sources of H
2
O, Cl, CO
2
,
and N
2
. The formation of the epithermal mineralization of the Stiavnica ore field was associated with the mixing
of magmatic fluid with low-concentration meteoric waters, and the fluid was in a heterogeneous state.

The El Cobre deposit is located in eastern Cuba within the volcanosedimentary sequence of the Sierra Maestra Paleogene arc. The deposit is hosted by tholeiitic basalts, andesites and tuffs and comprises thick stratiform barite and... more

The El Cobre deposit is located in eastern Cuba within the volcanosedimentary sequence of the Sierra Maestra Paleogene arc. The deposit is hosted by tholeiitic basalts, andesites and tuffs and comprises thick stratiform barite and anhydrite bodies, three stratabound disseminated up to massive sulphide bodies produced by silicification and sulphidation of limestones or sulphates, an anhydrite stockwork and a siliceous stockwork, grading downwards to quartz veins. Sulphides are mainly pyrite, chalcopyrite and sphalerite; gold occurs in the stratabound ores. Fluid inclusions measured in sphalerite, quartz, anhydrite and calcite show salinities between 2.3 and 5.7 wt% NaCl eq. and homogenisation temperatures between 177 and 300°C. Sulphides from the stratabound mineralisation display δ 34 S values of 0‰ to +6.0‰, whilst those from the feeder zone lie between −1.4‰ and +7.3‰. Sulphides show an intra-grain sulphur isotope zonation of about 2‰; usually, δ 34 S values increase towards the rims. Sulphate sulphur has δ 34 S in the range of +17‰ to +21‰, except two samples with values of +5.9‰ and +7.7‰. Sulphur isotope data indicate that the thermochemical reduction of sulphate from a hydrothermal fluid of seawater origin was the main source of sulphide sulphur and that most of the sulphates precipitated by heating of seawater. The structure of the deposit, mineralogy, fluid inclusion and isotope data suggest that the deposit formed from seawater-derived fluids with probably minor supply of magmatic fluids.

The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T) conditions of (ultra) high-temperature... more

The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T) conditions of (ultra) high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones (high-pressure metamorphic setting), and vertically by accumulation of mantle-derived magmas at the base of the crust (high-temperature metamorphic setting). Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H 2 O-activity fluids including high-density CO 2 and concentrated saline solutions (brines). These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust. This accumulation causes tectonic instability, which together with the heat input from the sub-continental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation. Ó 2015, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Unconformity related uranium mineralisation occurs in Banganapalle Formation of Palnad Sub-basin, Cuddapah Basin. Several evidences of hydrothermal activity exist in both basement granite and the cover sediments in Koppunuru and Rallavagu... more

Unconformity related uranium mineralisation occurs in Banganapalle Formation of Palnad Sub-basin, Cuddapah Basin. Several evidences of hydrothermal activity exist in both basement granite and the cover sediments in Koppunuru and Rallavagu Tanda (R.V. Tanda) uranium prospects of Palnad Sub-basin. Profuse development of fracture filled veins consisting of epidote–quartz, chlorite–quartz and quartz is observed at various depths above and below unconformity. Fluid–rock interaction during the formation of these veins has resulted in the alteration of feldspars and mafic minerals of granite and arkosic quartzite into a mineral assemblage consisting of various proportion of illite, chlorite, muscovite and pyrite, with the intensity of alterations being highest near to the unconformity. Pyrite is often associated with illite dominant alteration zone. We infer that circulation of basinal brine through basement granite and cover sediments was responsible for mobilising uranium from granite and its precipitation at favourable locations in cover sediments. Increase in pH of ore fluid due to illitisation and chloritisation of wallrock together with availability of carbonaceous matter and pyrite as reductant have controlled the localisation of uranium mineralisation in Banganapalle Formation.

The Holocene evaporite sequence in the Ras Shukeir area conformably overlies marine shell banks and cross-bedded to graded-bedded beach sands and gravels. The evaporite sequence is represented by gypsum-anhydrite layers that are... more

The Holocene evaporite sequence in the Ras Shukeir area conformably overlies marine shell banks and cross-bedded
to graded-bedded beach sands and gravels. The evaporite sequence is represented by gypsum-anhydrite layers that are
interbedded with mudstone layers. Field and petrographic investigations of the evaporite deposits revealed two facies types,
laminated evaporite facies (primary) and nodular to enterolithic anhydrite facies (diagenetic). The laminated evaporite
facies is subdivided, from the bottom to top, into regular laminated evaporite, chevron gypsum-algal micrite laminations
and wavy algal laminated evaporite. Based on their textures and fabrics, the regular and wavy laminated evaporite facies
are interpreted as primary deposits in a coastal lagoon and salina environment. The chevron gypsum-algal micrite facies
formed by the growth of chevron gypsum at the sediment-water interface within a shallow subtidal lagoonal environment
that was characterized by extensive benthic algal mats. The nodular to enterolithic anhydrite facies is secondary and formed
diagenetically within a siliciclastic supratidal sediment.
Some of the laminated evaporite facies have been diagenetically altered in a supratidal sabkha environment as evidenced
by the following: (1) the partial formation of nodular evaporite instead of laminated evaporite; (2) disruption of gypsum
laminations by plant roots and rootlets as well as by precipitation of lenticular gypsum on the root wall; and (3) partial
dissolution of halite laminae and the formation of wavy anhydrite laminae.
Consequently, the Holocene evaporites in the Ras Shukeir area were deposited in a shallow semi-closed to closed basin
that was separated from the Gulf of Suez trough. Changing sea level led to progradation of the evaporite facies from
subtidal to intertidal lagoon and salina to a supratidal sabkha.

Estimating values of permeability (k), efficient porosity (P) and hydraulic conductivity (K) by analysing field outcrops as analogue of geothermal reservoirs, is a timely theme useful for predictions during geothermal exploration... more

Estimating values of permeability (k), efficient porosity (P) and hydraulic conductivity (K) by analysing field outcrops as analogue of geothermal reservoirs, is a timely theme useful for predictions during geothermal exploration programs. In this paper we present a methodology providing k, P and K values, based on geometric analysis of quartz-tourmaline faults-vein arrays hosted in micaschist exposed in southeastern Elba Island (Tuscan Archipelago, Italy), considered as the analogue of rock hosting the so-called "deep reservoir" in the Larderello geothermal field. The methodology is based on the integration among structural geology, fluid inclusions results and numerical analyses. Through a detailed structural mapping, scan lines and scan boxes analyses, we have reconstructed three superposed faulting events, developed in an extensional setting and framed in the Neogene evolution of inner Northern Apennines. Geometrical data of the fault-veins array were processed by reviewing the basic parallel-plate model equation for k evaluation. Fluid inclusion analyses provided those salinity and pressure-temperature values necessary for defining density and viscosity of the parent geothermal fluids. Then, permeability, density and viscosity were joined to get hydraulic conductivity (K). Permeability is estimated between 5 × 10 −13 and 5 × 10 −17 m 2 with variations among the different faults generation, while the hydraulic conductivity is encompassed between 1.31 × 10 −8 and 2.4 × 10 −13 m/s. The obtained permeability and hydraulic conductivity values are comparable with those from several geothermal areas, and in particular from the Larderello geothermal field. The main conclusion is that the proposed integrated approach provides a reliable methodology to obtain crucial values, normally obtained after drilling, for developing numerical flow models of geothermal fluid path in active geothermal systems by field and laboratory analyses of analogue, exhumed, geothermal systems.

Lherzolite xenoliths containing fluid inclusions from the Ichinomegata volcano, located on the rear-arc side of the Northeast Japan arc, may be considered as samples of the uppermost mantle above the melting region in the mantle... more

Lherzolite xenoliths containing fluid inclusions
from the Ichinomegata volcano, located on the rear-arc side
of the Northeast Japan arc, may be considered as samples
of the uppermost mantle above the melting region in the
mantle wedge. Thus, these fluid inclusions provide valuable
information on the nature of fluids present in the subarc
mantle. The inclusions in the Ichinomegata amphibolebearing
spinel–plagioclase lherzolite xenoliths were found
to be composed mainly of CO2–H2O–Cl–S fluids. At equilibrium
temperature of 920 °C, the fluid inclusions preserve
pressures of 0.66–0.78 GPa, which correspond to depths
of 23–28 km. The molar fraction of H2O and the salinity
of fluid inclusions are 0.18–0.35 and 3.71 ± 0.78 wt%
NaCl equivalent, respectively. These fluid inclusions are
not believed to be fluids derived directly from the subducting
slab, but rather fluids exsolved from sub-arc basaltic magmas that are formed through partial melting of mantle
wedge triggered by slab-derived fluids.

Radioactive granitoids and cherty cataclasites are delineated in Thadisaoli–Khatgaon and Shahpur–Sujayatpur sectors in southeastern part of Nanded district, Maharashtra, which have recorded anomalous radioelemental contents (Granites:... more

Radioactive granitoids and cherty cataclasites are delineated in Thadisaoli–Khatgaon and Shahpur–Sujayatpur sectors in southeastern part of Nanded district, Maharashtra, which have recorded anomalous radioelemental contents (Granites: upto 1% U3O8 and 0.20% ThO2; Cherty cataclasites upto 0.11% U3O8 and <0.005% ThO2) and enrichment in trace element and rare metal and rare earth element concentration (Nb: upto 146ppm, Y: upto 226ppm, Zr: upto 559ppm and total REE: upto 2010ppm). The mineralised granitoids are affected by profuse pegmatitic/quartzo-feldspathic, quartz and epidote venations and mainly confined along the NE–SW and NNE–SSW faults/shear zones. Radioactive phases are represented by discrete uranium/thorium ore minerals (uraninite, -uranophane and thorite) and high content of resistates viz., apatite, zircon, allanite, sphene, cerianite, monazite and ilmenite.
Fluid inclusion studies of the mineralised and sheared granites, quartzo-feldspathic veins (QFVs) and quartz veins indicate the presence of 6 to 32µm size aqueous and carbonic inclusions of three principle types and represented by six phases viz., aqueous mono-, bi- and poly-phase, aqueous-carbonic, carbonic mono- and poly-phase. Aqueous biphase inclusions show wide range of salinity (0.71 to 19.99 wt.% eNaCl) and homogenisation temperatures (Th: 127.5–280.8ºC ) while aqueous-carbonic inclusions exhibit restricted salinity (5–8.4 wt.% eNaCl ) and Th (28.3–30.9ºC). The composition of these aqueous fluids varies from NaCl–KCl dominant in quartz veins and radioactive granite to MgCl2 dominant in sheared radioactive granite. Similarly, co-eval aqueous biphase and aqueous-carbonic inclusions have yielded 678–958 bar pressure and 201–233ºC temperature in quartz vein samples while higher values of 1120–1550 bar and 304–360ºC are indicated by sheared granite. The presence of more than one population without much change in fluid composition signifies their origin at different stages of deformation. Besides, mixing of a moderate temperature and low salinity fluid (meteoric/basinal brine) with a comparatively high temperature and hypersaline fluid (magmatic/evolved brine) might have also played important role in inclusion characteristics. Based on these fluid inclusion characteristics, it appears that multi-episodic hydrothermal activity under extensional tectonic regime in this fertile granitic province has led to precipitation of uranium along suitable structural aureoles from uraniferous hydrotherms.

The Saheb Fe (Cu) skarn deposit is located along the northwestern end of the Sanandaj-Sirjan Zone. This deposit occurs over an approximately 2 km distance along the contact zone between the Upper Cretaceous causative granite and the Upper... more

The Esfordi iron - apatite ore in Central Iran is located in Bafq metallogenic province. Stratigraphically most of the rock units belong to Precambrian and Cambrian sequences which the sedimentary and volcanic series are the most... more

The Esfordi iron - apatite ore in Central Iran is located in Bafq metallogenic province. Stratigraphically most of the rock units belong to Precambrian and Cambrian sequences which the sedimentary and volcanic series are the most spreading rock types and mineralization took place just within the volcanic-sedimentary unit of the mentioned
series. Study of REE contents of apatite in Esfordi iron-apatite ore shows high concentration of these elements. Zonal distribution of some REEs, e.g. La, is identified
which varies from center to the rim of apatite single crystal. Absence of negative Eu anomaly makes the Esfordi apatite distinctive from the igneous types and may indicate a
hydrothermal origin for Esfordi apatites .

Analyses of halogen concentration and stable chlorine isotope composition of fluid inclusions from hydrothermal quartz and carbonate veins spatially and temporally associated with giant unconformity-related uranium deposits from the... more

Analyses of halogen concentration and stable chlorine isotope composition of fluid inclusions from hydrothermal quartz and carbonate veins spatially and temporally associated with giant unconformity-related uranium deposits from the Paleoproterozoic Athabasca Basin (Canada) were performed in order to determine the origin of chloride in the ore-forming brines. Microthermometric analyses show that samples contain variable amounts of a NaCl-rich brine (Cl concentration between 120,000 and 180,000 ppm) and a CaCl2-rich brine (Cl concentration between 160,000 and 220,000 ppm). Molar Cl/Br ratios of fluid inclusion leachates range from ∼100 to ∼900, with most values between 150 and 350. Cl/Br ratios below 650 (seawater value) indicate that the high salinities were acquired by evaporation of seawater. Most δ37Cl values are between −0.6‰ and 0‰ (seawater value) which is also compatible with a common evaporated seawater origin for both NaCl- and CaCl2-rich brines.Slight discrepancies between the Cl concentration, Cl/Br, δ37Cl data and seawater evaporation trends, indicate that the evaporated seawater underwent secondary minor modification of its composition by: (i) mixing with a minor amount of halite-dissolution brine or re-equilibration with halite during burial; (ii) dilution in a maximum of 30% of connate and/or formation waters during its migration towards the base of the Athabasca sandstones; (iii) leaching of chloride from biotites within basement rocks and (iv) water loss by hydration reactions in alteration haloes linked to uranium deposition.The chloride in uranium ore-forming brines of the Athabasca Basin has an unambiguous dominantly marine origin and has required large-scale seawater evaporation and evaporite deposition. Although the direct evidence for evaporative environments in the Athabasca Basin are lacking due to the erosion of ∼80% of the sedimentary pile, Cl/Br ratios and δ37Cl values of brines have behaved conservatively at the basin scale and throughout basin history.

The motion of fluids which are incompressible could be described by the Navier-Stokes differential equations. However, the three-dimensional Navier-Stokes equations for modelling turbulence misbehave very badly although they are... more

The motion of fluids which are incompressible could be described by the Navier-Stokes differential equations. However, the
three-dimensional Navier-Stokes equations for modelling turbulence misbehave very badly although they are relatively simple-looking. The solutions could wind up being extremely unstable even with nice, smooth, reasonably harmless initial conditions. A mathematical understanding of the outrageous behaviour of these equations would greatly affect the field of fluid mechanics. In this paper, which had been published in an international journal in 2010, a reasoned, practical approach towards resolving the issue is adopted and a practical, statistical kind of mathematical solution is proposed.