Tertiary Mineralization Research Articles

ЭФФЕКТИВНОСТЬ КОМБИНАЦИЙ СРЕДСТВ ГИГИЕНЫ ПОЛОСТИ РТА У ДЕТЕЙ ПРИ РАЗНОМ УРОВНЕ АНТРОПОГЕННОЙ НАГРУЗКИ

Prevention of dental caries in children occupies one of the first places in pediatric dentistry. Indeed, during the period of tertiary mineralization of the enamel, it is necessary to pay special attention to the mineralization of the enamel of the teeth. The most urgent issue is the prevention of dental caries at this time. Correctly selected basic and additional oral hygiene products have a preventive effect. Dental caries has a multifactorial etiology. It can be a genetic factor, eating of carbohydrate foods and sugars in large amounts , poor oral hygiene,ecology and others. It has been proven that the technogenic load of the environment negatively affects the dental health of children. The children are most sensitive to environmental influences. The purpose of this work was to determine the most effective preventive action of the selected combinations of oral hygiene products for children of primary school age who were born and live in areas under different anthropogenic loads.
 Methodology. Various combinations of basic and additional oral hygiene products for primary school children, containing fluorine and amorphous nanohydroxyapatite, have been proposed. Studied: enamel caries resistance, oral fluid pH, oral fluid microcrystallization, tooth electrical conductivity, etc. According to the results of the study, the most effective combinations of oral hygiene products were selected for dental caries prevention of the primary school children who were born and live at different levels of anthropogenic load. The children and their parents were trained in the correct methodology for oral care and proper nutrition.

Experimental investigation on strength and durability properties of concrete using bauxite residue and metakaolin

From the previous barely any decades, various scientists are dealing with concrete by diffusing a few substances, for example, modern squanders and regular pozzolanic material to diminish the contamination just as efficient. Consequently, to decrease the natural' sway because of modern waste, the present work is started. This exploration paper educates about the alteration of concrete by adding two diverse mineral admixtures to it and inspects how mechanical properties of cement. Bauxite buildup (B&R) and Metakaolin (M&K), which are better than customary Portland concrete, are presented as optional and tertiary mineral admixtures. Aside from typical solid, four [BR&MK concrete blends are set up by in part supplanting the concrete with BR&MK mix at interims of 2.5%, 5%, 7.5%, 10%, 12.5%, and 15%. BR&MK mix is set up by including bauxite buildup and metakaolin in equivalent extents. Droop cone test, compressive, flexural and split elasticity tests are directed to realize the usefulness just as mechanical obstruction of cement. Results are demonstrating that BR&MK solid blend in with a 10% substitution level has indicated a more prominent improvement in mechanical properties of cement.

Airborne electromagnetic signature of a paleochannel uranium deposit

SUMMARY Reptile Uranium, a wholly owned subsidiary of Deep Yellow Ltd., has been actively exploring four exclusive prospecting licenses (EPLs) in Namibia since 2007. Prior exploration of this area in the 1970’s and 80’s resulted in the discovery of extensive Tertiary uranium mineralization hosted by paleochannels. Detailed airborne radiometric data acquired in 2007 shows good correlation with known surficial mineralization, but provides no depth information about the known channels, and does not identify potential buried channels. In 2008, Aeroquest Surveys completed an AeroTEM helicopter time domain electromagnetic (HTEM) survey over the four EPLs. The electromagnetic (EM) data proved to be an excellent tool for mapping the conductive material associated with both near-surface and buried paleochannels. There is generally good correlation between the stronger AeroTEM responses and the known mineralization. The HTEM data were inverted using a 1D layered earth algorithm to model the distribution of conductivity laterally and with depth. The modeled data effectively describe the lateral extent, thickness and relative conductivity of the paleochannels and have been found to be very useful in directing the ongoing drill program both for the delineation of known paleochannels and for the drilling of previously unknown paleochannels. Successful trenching and drill results from the Tubas-Oryx-Tumas paleochannel system clearly illustrate the important role that the HTEM data has played in the ongoing exploration on this project.

Clinical and morphological characteristics of enamel during pigment hypoplasia of tooth tissues.

Background. Dystrophic changes in enamel and dentin occur as a result of metabolic disturbances in the hard tissues of the tooth and are characterized by its insufficient formation and mineralization, or excessive accumulation of pigments in the form of spots. The accumulation of pigment (qualitative and quantitative) is irreversible, that is, pigmentary dystrophy has no reverse development and remains in the enamel for life. Objectivе. To analyze the structural changes in tooth enamel in case of pigmentary dystrophy. Methods. After extraction, the teeth were embedded with Epon-812 epoxy. After polymerization, the obtained block was cut with a separating disk on thin sections 0.25 mm thick, an aluminum layer was applied to the preparations in vacuum and examined on a scanning electron microscope REM - 102E with an accelerating voltage of 30 kV. Results. It has been established that in case of chronic discolorites the enamel is partially fragmented, the phenomena of lysis of the enamel are determined. Lacunae are observed on the enamel-dentin border. Enamel preparations with congenital discolorations revealed a thickening of enamel prisms, mosaic expressiveness of Retzius lines. In exogenous pigmentary dystrophy, the main changes are established on the enamel surface. The phenomena of focal fragmentation, diffuse thinning of enamel prisms (atrophic changes) were observed. In endogenous pigmental dystrophy, the main changes are determined by the enamel-dentin boundary. Prisms are thinned and fragmented. Conclusion. Congenital dystrophy of pigment has a diffuse nature and affects the entire thickness of the enamel, which is caused by disorders in the process of histogenesis. With acquired discolorites, the localization of pathological changes depends on the etiology - endogenous, or exogenous. In endogenous pigmental dystrophy, morphological changes are found in the surface layers of enamel, developing as a result of disruption of the tertiary mineralization process, which create favorable conditions for the penetration of pigments by reducing the content of inorganic substances. In endogenous pigmental dystrophy, major changes develop in the deep layers of enamel adjacent to the dentine-enamel border. The source of pigment in this case is enamel spindles, which have a low content of inorganic substances and penetrate into the enamel on 1/3 of its thickness.

The Hydrothermal Fluid Evolution of Vein Sets at the Pipeline Gold Mine, Nevada

The origin of sediment-hosted Nevada gold deposits has been highly debated, especially regarding the relative contribution of multiple mineralizing events, particularly relating to the Cretaceous. We examined the Pipeline gold mine in north-central Nevada, focusing on data from the four vein sets in this atypical deposit where there is evidence for Cretaceous gold mineralization. Only the third, a quartz-sericite-pyrite-calcite vein set, has any link with the alteration styles and gold mineralization within the Pipeline deposit. Our geochemical results from fluid inclusion microthermometry and gas analysis show that the fluids from which quartz deposited were sourced from condensing magmatic volatiles and were trapped at ~300 °C and 2 kbar lithostatic pressure (~8 km). 40Ar/39Ar dating of sericite demonstrates that the quartz-sericite-pyrite veins formed at ~92 Ma, matching the dates of gold-associated epigenetic illite. Ore fluids enriched in CO2 and H2S caused decarbonation thereby releasing Fe2+ that reacted with H2S to form pyrite. Decreasing H2S destabilized gold bisulfide complexes and deposited gold. We conclude that this process can occur in a single Cretaceous event in advance of potential Tertiary mineralization.

MINERALOGY OF NEUTRAL MINE DRAINAGE IN THE TAILINGS OF SIDERITE-Cu ORES IN EASTERN SLOVAKIA

This work presents the results of investigation of the primary minerals and their weathering products of two tailing ponds near the villages of Rudňany and Slovinky in eastern Slovakia. The tailings are near-neutral or slightly alkaline (pH = 7.2–8.8) because the acidity generated by the decomposition of the sulfides is efficiently neutralized by the abundant carbonate minerals. The most frequent primary gangue minerals are siderite, quartz, barite, and muscovite. The prevailing primary sulfide minerals in both tailing ponds are pyrite and chalcopyrite; less common are tetrahedrite and arsenopyrite. The most frequent secondary and tertiary ( i.e. , formed in the tailings, not in the oxidation zone of the deposits) minerals at both localities are iron oxides, either goethite or poorly crystalline hydrous ferric oxide. Other minerals (cuprite, malachite, delafossite; identified by X-ray microdiffraction or Raman spectroscopy) are minor or rare and occur only in Slovinky. The iron oxide minerals are enriched in a suite of elements, including Cu, Si, Ca, Zn, As, Mg, and Mn. The transformations of the poorly crystalline hydrous ferric oxide to goethite and maturation of goethite is controlled by both high-valence tetrahedral cations (Si, As, P) and lower-valence octahedral cations (Cu), as shown by the measurements of the size of coherently diffracting domains in goethite and the chemical composition of goethite. The iron oxide minerals, by virtue of their adsorption capacity, prevent separate minerals of many metals and metalloids (Cu, Ca, As, Sb) from nucleating and growing, and therefore control the entire neutral mine drainage (NMD) system. Geochemical modeling of the discharged waters shows that all common Cu and ferric arsenate minerals are strongly undersaturated, confirming the central role of iron oxide phases in the NMD system.

Petrogenesis of Granitoids, U-Pb zircon geochronology, Sr-Nd Petrogenesis of granitoids, U-Pb zircon geochronology, Sr-Nd isotopic characteristics, and important occurrence of Tertiary mineralization within the Lut block, eastern Iran

توده های نفوذی ترشیری (گرانیتوئیدها) در مناطق مختلفی از بلوک لوت در استان‌های خراسان رضوی و جنوبی مورد مطالعه قرار گرفت. عمده توده ها از نوع نیمه‌عمیق با بافت پورفیری بوده و ترکیب آنها از دیوریت تا گرانیت متغیر است، ولی غالبا مونزونیتی هستند. این توده ها (به استثنای هیرد) متعلق به سری مگنتیت (نوع I) بوده و به‌طور عمده از نوع متاآلومینوس هستند. اغلب توده‌های نفوذی که کم و بیش نیز همراه با کانی سازی هستند از نوع غنی از پتاسیم هستند، در حالی که توده های نفوذی بدون کانی سازی نجم آباد از نوع سدیک است. ماگمای نجم آباد با توجه به مقدار Nb 30، نسبت 87Sr/86Sr اولیه کمتر از 7053/0 و مقدار eNd در حدود 16/5+ در زون فرورانش و از اعماق بیشتر منشأ گرفته و کمترین آلودگی با پوسته قاره ای را داشته است، در حالی که توده های منطقه کیبرکوه با بالاترین مقدار 17 ppm Nb >، نسبت کم < 2 Zr/Nb، نسبت 87Sr/86Sr اولیه بیش از 707/0 و مقدار eNd کمتر از 3- بیشترین اختلاط با پوسته قاره ای را نشان می دهد. تهی‌شدگی شدید عناصر HREE در توده های نفوذی نجم آباد و نسبت (La/Yb)N بیش از 17 تا 23 نشان‌دهنده تشکیل ماگما در عمق پایداری گارنت است. برپایه الگوی REE و مقدار Eu/Eu* بین 8/0 تا 1، توده های مناطق ماهرآباد، خوپیک، چاه شلجمی، ده‌سلم و کوه شاه، کالک‌آلکالن هستند و ماگمای آنها در شرایط اکسیدان تشکیل شده است، ولی کیبرکوه با مقدار Eu/Eu* کمتر از 8/0 با پوسته قاره ای احیایی آلوده شده است. توده های نفوذی همه مناطق غیر از نجم آباد در محدوده مشترک ماگمای کالک‌آلکالن نرمال با آداکیتی قرار دارد، ولی توده های نجم آباد به ترکیب ماگمای آداکیتی شباهت دارند. سن گرانیتوئیدها بین ائوسن میانی تا الیگوسن تحتانی بوده و از 3/43 میلیون سال در کیبرکوه در شمال تا 3/33 میلیون سال در چاه‌شلجمی در جنوب کاهش می یابد. مقدار نسبت 87Sr/86Sr اولیه نیز از شمال به جنوب همراه با کاهش سن توده های نفوذی از کیبرکوه به‌طرف چاه‌شلجمی، از 7077/0 به 7047/0 کاسته می شود. توده های نفوذی ماهرآباد، خوپیک، ده سلم و چاه شلجمی مقدار eNd بین 5/0+ تا 49/2+ و مقدار نسبت 87Sr/86Sr اولیه کمتر از 7055/0 دارند که نشان‌دهنده ماگمای مشتق‌شده از ذوب بخشی پوسته اقیانوسی است. سن سنگ منشأ گرانیتوئیدها (TDM) که براساس ایزوتوپ های Sm-Nd محاسبه شده است، نشان می دهد که توده های نفوذی از پوسته های اقیانوسی با سن‌های متفاوتی منشأ گرفته اند، به‌طوری‌که ماگمای منطقه کیبرکوه از قدیمی‌ترین پوسته اقیانوسی در حال فرورانش (840 میلیون سال)، نشأت گرفته و بیشترین آلایش پوسته ای را در طی صعود متحمل شده است. ولی توده های نجم آباد از یک پوسته اقیانوسی جوان‌تر (سن 360 میلیون سال) منشأ گرفته و کمترین آلودگی را با پوسته دارند. ماگمای مناطق ده‌سلم و چاه‌شلجمی نیز که در برخی موارد ژئوشیمی متفاوتی با ماگمای مناطق ماهرآباد و خوپیک نشان می دهند، از پوسته‌های اقیانوسی جداگانه ای منشأ گرفته اند که حدود 200 میلیون سال با یکدیگر اختلاف سنی داشته اند. فاصله زمانی بین 42 تا 33 میلیون سال قبل (ائوسن میانی تا اوایل الیگوسن)، مهمترین پنجره زمانی کانی سازی در شرق ایران و محدوده استان خراسان جنوبی است. انواع کانی سازی مس- طلا پورفیری، طلای مرتبط با توده های نفوذی احیایی، طلای اپی ترمال سولفید بالا، اسکارن آهن، رگه های Pb-Zn-Sb و IOCG شناسایی شده اند. لذا گرانیتوئیدهای تشکیل شده در محدوده زمانی 42 تا 33 میلیون سال که در بلوک لوت و شمال آن قرار دارند، برای این مجموعه کانی سازی پتانسیل دارند.

Geochemical signature of surface water and stream sediments of a mineralized drainage basin at NE Chalkidiki, Greece: A pre-mining survey

The geochemical characteristics of surface water and stream sediments in Asprolakkas drainage basin, an area of Tertiary mineralization within amphibolite, located at NE Chalkidiki peninsula, Greece, were investigated in order to establish the geochemical baseline conditions prior to any type of new mining activities. The area represents the only example of active mining and processing of base metal sulfide ore in Greece and also includes an unmined porphyry Cu–Au ore deposit at Skouries. In a wider context, this research represents a pre-mining baseline geochemical study that can be used as an analog for similar metallogenetic provinces in areas with a Mediterranean type climate.Concentrations of dissolved major ions and trace metals displayed wide variability within the study area. Kokkinolakkas stream, draining the exploited Pb–Zn (±Ag) ore bodies, is strongly influenced by chemical weathering of sulfide minerals and presents elevated levels of SO4 (429–857mgl−1), Pb (4–64μgl−1), Zn (290–1350μgl−1), Mn (1680–7899μgl−1), Ni (12–50μgl−1), Cd (2–8μgl−1), As (8–45μgl−1) and Sb (9–16μgl−1). Stream water of unmined areas demonstrated a different chemical composition with elevated values mainly for Pb (up to 45μgl−1) and As (up to 141μgl−1). Hydrological conditions highly influence the behavior of major elements and metals. Stream bed sediments from Kokkinolakkas and Tsarkia Lakkos, located at the head waters of Asprolakkas basin, have anomalous values in Pb (1165–3439mgkg−1), Zn (1368–4538mgkg−1), As (964–2714mgkg−1), Sb (30–70mgkg−1), Cd (3.8–21.6mgkg−1) and Mn (6811 up to >10,000mgkg−1). Mobility of selected trace metals was investigated through the application of a 5-step sequential extraction procedure. Results show that, despite the high total metal content, the majority of analyzed elements are mainly bound to relatively immobile operationally defined geochemical phases of amorphous to poorly crystalline Fe and Mn oxides and the residual fraction. Considering the planned mining developments in the area, the results of this study may assist mine planners to set realistic goals for monitoring and remediation programs.

A mineralogical, geochemical, and microbiogical assessment of the antimony- and arsenic-rich neutral mine drainage tailings near Pezinok, Slovakia

The mineralogical composition of mining wastes deposited in voluminous tailing impoundments around the world is the key factor that controls retention and release of pollutants. Here we report a detailed mineralogical, geochemical, and microbiological investigation of two tailing impoundments near the town of Pezinok, Slovakia. The primary objective of this study was the mineralogy that formed in the impoundment after the deposition of the tailings (so-called tertiary minerals). Tertiary minerals include oxyhydroxides of Fe, Sb, As, Ca and are present as grains and as rims on primary ore minerals. X-ray microdiffraction data show that the iron oxyhydroxides with abundant As are X-ray amorphous. The limiting (lowest) Fe/As (wt/wt%) ratio in this material is 1.5; beyond this ratio, the hydrous ferric oxide does not retain arsenic. The grains with less As and little to moderate amounts of Sb are goethite; the grains where Sb dominates over Fe are poorly crystalline tripuhyite (FeSbO4). Even the most heavily contaminated samples (up to 29 wt% As2O5) are populated with diverse communities of microorganisms including typical arsenic-resistant heterotrophic species as well as iron reducers and sulfur oxidizers. Several recovered clones cluster within phylogenetic groups that are solely based on environmental sequences and do not contain a single cultivated species, thus calling for more work on such extreme environments.

Lead-isotope and trace-element geochemistry of Paleoproterozoic metasedimentary rocks in the Lead and Rochford basins (Black Hills, South Dakota, USA): Implications for genetic models, mineralization ages, and sources of leads in the Homestake gold deposit

Mixed, silicate–carbonate–sulfide facies, banded iron formations with elevated detrital components were deposited in the Northern Black Hills during middle Paleoproterozoic time, between 2.012 and 1.974 Ga (Homestake Iron Formation and equivalents) and at ≤1.887 Ga (Rochford Iron Formation). These iron formations, deposited atop shales and basalts in intracontinental rifted basins separated in time by ∼80–130 Myr, are the hosts of extensive, late Paleoproterozoic gold mineralization. Gold/sulfide ore bodies occur within dilated segments of late-stage ductile–brittle shears that formed after isoclinal folding related to Wyoming–Superior continental collision. Lead stepwise leaching (PbSL) data for monazite-bearing garnet separated from a sample of Homestake Iron Formation has yielded an isochron age of 1746 ± 10 Ma (2 σ; MSWD = 0.42), which represents a maximum age for both the isoclinal folding and subsequent gold mineralization. Monazite-bearing garnet from a nearby “Harney Peak”-type granitic pegmatite, believed to be coeval with latest-stage, semibrittle shears and quartz veins that crosscut Homestake ore bodies, has yielded a PbSL isochron age of 1713 ± 10 Ma (2 σ, MSWD = 4.1), which probably represents a minimum age for the gold event. Pb isotopes of sulfides from “replacement ore” and “shear ore” within the Homestake Iron Formation cannot distinguish between these distinct ore types. However, both Pb isotopes and REY (rare earth and yttrium) abundances indicate slight disequilibrium between the ore sulfides and the barren iron formation, thus revealing an epigenetic (sensu stricto) component to the gold mineralization. The Pb-isotope characteristics of the ore further reflect an admixed component with low 232Th/ 204Pb and variable Th/U ratios in addition to compositions directly derived from BIF-typical leads. This added component corresponds to Pb from the anoxic metasedimentary rocks directly underlying the iron formations and from the nearby pegmatitic granite. The apparent Pb-isotopic match between ore and granite is further consistent with the PbSL data for “shear ore”-type arsenopyrite, which define an isochron age of 1719 − 45 + 38 Ma (2 σ, MSWD = 0.2), and by a striking overlap of the Pb-isotopic data fields defined by the Homestake galenas and pegmatitic feldspars. The Precambrian ore leads are therefore best explained as mixtures of magmatic-hydrothermal and host-rock-mobilized leads. The Lead area also contains significant gold-bearing deposits of Tertiary age, which are hosted in both Paleoproterozoic and Phanerozoic rocks. Tertiary mineralization was temporally and spatially related to coeval plutons emplaced during Laramide uplift of the Black Hills and represents the final mineralization event recognized in the Homestake Mine area. Like the Precambrian galena leads, the leads of Tertiary galena hosted by middle Paleoproterozoic rocks (including the Homestake Iron Formation) define a trend best explained by mixtures of Pb derived from magmatic fluids exsolved from Tertiary intrusives and Pb leached from the same country rocks that contaminated the granite-derived hydrothermal fluids ascending through them during the much earlier shearing-and-mineralization event inferred at ∼1730–1715 Ma.

Contamination of surface waters by mining wastes in the Milluni Valley (Cordillera Real, Bolivia): Mineralogical and hydrological influences

This study is one of very few dealing with mining waste contamination in high altitude, tropical-latitude areas exploited during the last century. Geochemical, mineralogical and hydrological characterizations of potentially harmful elements (PHEs) in surface waters and sediments were performed in the Milluni Valley (main reservoir of water supply of La Paz, Bolivia, 4000 m a.s.l.), throughout different seasons during 2002-2004 to identify contamination sources and sinks, and contamination control parameters. PHE concentrations greatly exceeded the World Health Organization water guidelines for human consumption. The very acidic conditions, which resulted from the oxidation of sulfide minerals in mining waste, favoured the enrichment of dissolved PHEs (Cd > Zn » As >> Cu ∼ Ni > Pb > Sn) in surface waters downstream from the mine. Stream and lake sediments, mining waste and bedrock showed the highest PHE content in the mining area. With the exception of Fe, the PHEs were derived from specific minerals (Fe, pyrite; Zn, Cd, sphalerite, As, Fe, arsenopyrite, Cu, Fe, chalcopyrite, Pb, galena, Sn, cassiterite), but the mining was responsible for PHEs availability. Most of the PHEs were extremely mobile (As > Fe > Pb > Cd > Zn ∼ Cu > Sn) in the mining wastes and the sediments downstream from the mine. pH and oxyhydroxides mainly explained the contrasted availability of Zn (mostly in labile fractions) and As (associated with Fe-oxyhydroxides). Unexpectedly, Pb, Zn, As, and Fe were significantly attenuated by organic matter in acidic lake sediments. Hydrological conditions highly influenced the behaviours of major elements and PHEs. During wet seasons, major elements were diluted by meteoric waters, whereas PHEs increased due to the dissolution of sulfides and unstable tertiary minerals that formed during dry seasons. This is particularly obvious at the beginning of the wet season and contributes to flushes of element transport downstream. The high altitude of the study area compensates for the tropical latitude, rendering the geochemical behaviour of contaminants similar to that of temperate and cold regions. These results might be representative of geochemical processes in ore deposits located in the high Andes plateau, and of their influence on PHE concentrations within the upper Amazon basin. Although mining activities in this region stopped 10 years ago, the impact of mining waste on water quality remains a serious environmental problem.

U–Pb isotopic constraints on diachronous metamorphism in the northern Monashee complex, southern Canadian Cordillera

U–Pb isotopic data from the northern Monashee complex, one of the deepest structural exposures in the southern Canadian Cordillera, indicate that the age of metamorphism varies according to structural position in a 6 km thick section. This metamorphism resulted in an unusual sequence in which rocks with the lowest‐grade mineral assemblage (kyanite–sillimanite–staurolite–muscovite) are underlain and overlain by higher‐grade rocks. Xenotime and monazite U–Pb dates vary progressively from 64 Ma in the structurally highest rocks to 49 Ma in the deepest rocks. Discordant U–Pb ages from Proterozoic and Cretaceous monazite and titanite are used to interpret the thermal significance of the early Tertiary dates. The discordant analyses define linear arrays with lower intercepts that broadly overlap with early Tertiary, and the amount of discordance varies with structural level; it is least in the deeper rocks and greatest in higher rocks. Electron microprobe work showed that the monazite discordance in the deeper rocks resulted from Tertiary mineral overgrowth and recrystallization rather than Pb diffusion. We use previous studies of Pb diffusion and the fact that Proterozoic monazite and titanite suffered only negligible to moderate amounts of diffusive Pb loss to contend that elevated temperatures (c. 600–650 °C are inferred from pelitic mineral assemblages) existed in the deeper rocks for a short duration, perhaps a few million years. The downwards younging 64–49 Ma U–Pb dates are interpreted as closely reflecting xenotime and monazite growth ages rather than cooling ages or substantially reset ages based on the lack of Pb diffusion in monazite and the previously obtained 40Ar/39Ar data which suggest that rapid cooling occurred immediately after the U–Pb dates. In addition, growth ages are interpreted as thermal peak ages based on U–Pb dates from coeval kyanite‐bearing leucosomes, the consistent nature of the U–Pb dates throughout the study area, and petrographic relationships which suggest that monazite grew before or during development of the syn‐metamorphic foliation. These interpretations lead us to conclude that metamorphism was diachronous according to structural level, with higher rocks attaining peak temperatures and cooling rapidly while deeper rocks were heating towards a thermal peak that was attained a few million years later. This thermal scenario requires that higher rocks cannot have been the heat source for the deeper metamorphism, as was previously proposed.

Tertiary mineralization and magmatism, East Greenland: lead isotope evidence for remobilization of continental crust

Well-defined lead isotope signatures of sulphides from mineral occurrences associated with Tertiary igneous rocks in East Greenland fall in two distinct groups: (1) sulphide samples from the region south of Scoresby Sund (Kangerlussuaq igneous complex) have lead characterized by retarded uranogenic evolution and slightly elevated thorogenic isotopic ratios; (2) sulphide samples from the region north of Scoresby Sund (Werner Bjerge, Kap Simpson and Kap Broer Ruys igneous complexes) have lead compositions typical of modern average terrestrial lead. These distinct signatures in both conventional and 208 Pb/ 204 Pb – 207 Pb/ 204 Pb diagrams lie within linear trends defined by previously published lead isotope data for unmineralized Tertiary basalts and intrusive rocks. The linear trends are mixing lines between the lead in the Tertiary mantle-derived magmas and lead remobilized from continental crust. Tertiary magmas in the region south of Scoresby Sund remobilized and incorporated lead from low- μ, high- 208 Pb/ 204 Pb crustal sources similar in isotope composition to Archaean high-grade metamorphic gneisses exposed in the area. Non- to sub-parallel, distinct lead mixing lines in the 208 Pb/ 204 Pb – 206 Pb/ 204 Pb diagram for the Tertiary igneous complexes in this region suggest strong heterogeneity of the remobilized crust. More than one-half of the lead from sulphide mineral occurrences within the Kangerlussuaq alkaline intrusive complex may be derived from local continental crust. In the region north of Scoresby Sund the Tertiary magmas remobilized moderately radiogenic lead from local basement and sedimentary basins: Palaeoproterozoic–Mesoproterozoic gneisses, Neoproterozoic–Ordovician sediments, Caledonian granites and Palaeozoic–Mesozoic sediments. These crustal rocks lack the very low 206 Pb/ 204 Pb and 207 Pb/ 204 Pb ratios typical of the gneisses from the Kangerlussuaq region, and mixing trends between mantle-derived and crustal lead are therefore much less extensive. However, because the mantle-derived magmas had very low total lead contents, even small additions of crustal lead are traceable. Sulphide-mineralized alkaline intrusive complexes are shown to be highly contaminated with crustal lead, and it is further shown that the pre-Tertiary rocks of North-East Greenland are likely local crustal sources of lead for contaminated Tertiary plateau basalts. Many stratabound, sediment-hosted hydrothermal base metal occurrences in the Palaeozoic–Mesozoic Jameson Land Basin are thought to be Tertiary in age, but do not appear to contain Tertiary, igneous-derived lead. On the contrary, the hydrothermal alteration zones associated with several of the mineralized Tertiary igneous complexes attest to extensive fluid/rock mass transfer; lead and other base metals were leached from the country rocks, homogenized, and incorporated into sulphide minerals.

Modeling Stduy of Effects of Short-Lived Radionuclide Fixation on Decay Chain Radionuclides Migration.

Abstract Effects of a short lived radionuclide fixation to minerals during alteration process from a primary mineral (Ml) to tertiary mineral (M3) through secondary mineral (M2) on a decay chain radionuclides migration (DCRM) have been studied based on mathematical simulation studies. The mathematical migration model in which a daughter radionuclide, N2, corresponds to a short lived radionuclide and is fixed to M2 during alteration from Ml to M2, is proposed. Also, a fraction of the granddaughter radionuclide, N3, is assumed to be released from M2 into a solution during the alteration process from M2 to M3. The model studies lead the delay in the migration of N3, with the delay becoming remarkably enhanced if the fixation rate constant of N2 is greater than the decay constant of N2. Whereas, the delay is reduced by the release of N3 with a faster rate than the decay constant of N3. Therefore, it is important clarify decay chain radionuclides fixation and release mechanisms during an alteration process.

MINERAL ORE CO-PRODUCT (IRON OXIDE) AS A GROWTH MEDIUM COMPONENT

The utility of Ironrich (IR), a tertiary mineral co-product from TiO2 production, as a growth medium component was investigated. All complementary bulking components (10 to 50% volume) gave reduced shoot fresh weights of tomato, impatiens or perennial ryegrass relative to Fairgrow (FG, co-composted solid waste and sewage sludge). Shoot fresh weights of impatiens and tomato grown in 50% IR with FG were similar to those grown in commercial peat-lites. When provided 200 mg N litre-1 daily, chard shoot fresh weights, beet root fresh weights, and tomato fruit fresh weights from plants grown in 50% IR plus 50% FG were not significantly different from those grown in 50% silt loam plus 50% FG. Tissue Cd, Cr, Ni, and Pb concentrations from plants grown in 50% combinations of FG with IR or silt loam were below the limits of detection. IR plus FG with N-P-K fertilization provided a satisfactory greenhouse growth medium. We project that IR + FG will constitute a satisfactory synthetic topsoil.

Incompletely reset RbSr systems from a Cambrian red-rock granophyre terrane, Florida Mountains, New Mexico, U.S.A.

A zircon separate from a syenite from the Florida Mountains, near Deming, southwest New Mexico, yields a 514 ± 3-Ma concordia upper-intercept age. However, RbSr isochron dates from syenite and other igneous core rocks in the Florida Mountains range from ∼ 519 to ∼ 381 Ma. The RbSr dates are based on scattered linear arrays suggestive of open-system conditions for the rocks. Calculated initial 87 Sr 86 Sr ratios are highly variable for presumably coeval rocks, and some are anomalous values below 0.699. KAr dates from these igneous core rocks range from 555 to 418 Ma, while an andesite dike, possibly associated with Tertiary mineralization in the area, yields a date of 2.7.9 Ma. The zircon UPb concordia age can be reconciled with the available stratigraphic controls that require a pre-Middle-Ordovician age for some granite and syenite core-rock exposures. Collectively, the geochronologic data argue for Early Paleozoic plutonism at ∼ 510–550x Ma, with a resetting event affecting the RbSr and KAr systematics in the syenite and alkali granite in the Tertiary. The resetting mechanism may have involved Sr loss, possibly through ion-exchange reactions between feldspar and moderately heated fluids, as well as loss of Ar and/or addition of K in the syenites, alteration of the Th/U ratio in the syenite and granite, and production of brick-red K-feldspars due to the incorporation of minute hematitic inclusions. δ 18O-values for several whole-rock samples range between + 5.8 and + 9.2‰, consistent with a high water/rock ratio and alteration temperatures of ⪅ 300°C. World-wide, red-rock granophyre terranes commonly yield discordant RbSr and UPb dates, with RbSr dates scattered and systematically younger than UPb ages. We suggest that red-rock granophyres are inherently undatable by the RbSr technique because of Sr loss from K-feldspars during penetration of Fe-oxidizing solutions.

Early Late Cretaceous-early Tertiary gold mineralization; a galena lead isotope study of the Bridge River mining camp, southwestern British Columbia, Canada

The Bridge River gold camp, 180 km north of Vancouver, Canada, produced more gold than any other camp in British Columbia over its 70 years of operation (130 metric tons or 4 million oz), mainly from the Bralorne and Pioneer deposits. A compilation of new and existing lead isotope ratios from 20 widespread and diverse deposits in the Bridge River camp shows a distinct clustering of data. This is interpreted to be the expression of a single protracted but episodic mineralizing event coinciding with the emplacement of the Coast Plutonic Complex during early Late Cretaceous to early Tertiary time (90-45 Ma). The timing of this event is constrained at Bralorne by a premineral albitite dike set (91.4 + or - 1.4 Ma by U-Pb on zircon) and a late intramineral hornblende porphyry dike set (85.7 + or - 3 Ma by K-Ar on hornblende). Late lamprophyre dikes that crosscut the mineralized veins, dated at 43.5 + or - 1.5 Ma by K-Ar on biotite, set a lower age limit for the mineralization. The host rocks, the Bralorne intrusions, have no genetic relation to the mineralization since they are Early Permian (270 + or - 5 Ma by U-Pb on zircon).The conclusion that all mineralization is related to a coherent event is in accord with recognition of a districtwide mineral zoning scheme by Woodsworth, Pearson, and Sinclair. In this scheme, a sequence from high-temperature Au-As-W-Mo through intermediate Sb-Ag-Au-As to low-temperature Sb-Hg vein assemblages as generated from southwest to northeast within the thermal aureole of the Coast Plutonic Complex. Stable isotope and temperature data from other workers support this northeastly decreasing gradient in mineralization temperature.Clustered lead isotope data define a trend that plots between model Pb isotope curves of Doe and Zartman for the upper crust and the mantle. This trend is interpreted to be a mixing line, between primitive mantle-type lead and more radiogenic lead, by one or a combination of two postulated processes: between two groups of rocks (more primitive oceanic volcanics and more radiogenic upper crustal volcanic arc-clastic rocks) by a meteoric thermal system generated by the emplacement of the Coast Plutonic Complex, or between less and more radiogenic magmas during the emplacement of the Mesozoic-Cenozoic volcanics and intrusion hosting the deposits. The accreted nature of the host oceanic and arc terranes is emphasized by the differences between the model proposed and the upper crustal shale curve model of Godwin and Sinclair, which represents much of the locally adjacent autochthonous portion of the Canadian Cordillera.

The Zacatecas mining district; a Tertiary caldera complex associated with precious and base metal mineralization

The Zacatecas mining district is located in north-central Mexico, at the transition of the Sierra Madre Occidental and Mesa Central physiographic provinces. The existence of a deeply eroded caldera is evidenced by concentric and radial fracture systems, a ring fracture zone, a thick pile of ash-flow tuffs, several subvolcanic plugs, a lava-flow dome, two partially superimposed asymmetric collapse features, and a resurgent dome. The prevolcanic floor of the caldera is represented by a Late Cretaceous microdiorite laccolith which intruded metasediments of possible Triassic age, all overlain by a continental red conglomerate of Paleocene age.The volcanic center is spatially associated with economic mineralization and exerted strong structural control on the formation of the deposits. Three groups of veins are recognized, varying in ore assemblage and structural position: (1) the most important and extensive is the Ag-(Pb, Zn, Cu, Au) system, occurring in concentric and tangential faults and fractures that cut precaldera rocks; (2) the Au-Ag(Se) system, located in radial fractures that were emplaced in the caldera-fill host rocks; and (3) the F system, subparallel to the other margin of the caldera and also located in caldera-fill lithologies. Silver, the dominant precious metal, occurs mainly as acanthite, silver sulfantimonides, such as freibergite, and native silver. Free gold and electrum were identified optically, and aguilarite (Ag 2 SeS) was identified for the first time in the district. Pyrite, sphalerite, galena, and chalcopyrite are also present. Gangue minerals are mainly quartz and calcite.Preliminary fluid inclusion data on samples from the Cantera vein system, which contains precious and base metals, fall in the temperature range of 300 degrees to 160 degrees C. The early Tertiary mineralization in the district is epithermal and controlled by volcanotectonic features, modified by erosion, oxidation, and supergene enrichment.

Determination of radiogenic isotopes ( [formula omitted], [formula omitted] and [formula omitted]) in fluid inclusion waters: An example from the Bluebell Pb-Zn deposit, British Columbia, Canada

Rb, Sr, Pb, Nd and Sm isotopes were determined in fluid inclusion waters extracted from quartz samples of the Bluebell Pb-Zn deposit, British Columbia. The results demonstrate that radiogenic isotopes in fluid inclusion waters can constitute useful geochronological and genetic tools when applied in conjunction with geological, geochemical and other geochronological studies. Rb Sr isotopes of fluid inclusion waters and of mineralized marbles hosting the deposit indicate a Tertiary mineralization age of 19.2 ± 5.9 Ma, and an initial 87Sr 86Sr ratio of 0.7143. This Rb Sr date is in general agreement with a Cenozoic age suggested by geologic field relations described by Irvine (1957) and Fyles (1967). Pb isotope data suggest two isotopically distinct fluids, one less radiogenic and similar to values measured on galenas, and the other more radiogenic. This is in agreement with Ohmoto and Rye's (1970) hypothesis of two-meteoric-hydrothermal fluids, and Lecouteur's (1973) convection cell model. Nd and Sm isotope also suggest mixing of fluids. Both Pb Pb and Nd Sm data suggest very old lower and upper crustal materials as possible source of the metals.

The mineral occurrences of central East Greenland

The present monograph on the mineral occurrences of central East Greenland is the result of an agreement between Nordisk Mineselskab A/S and the Mineral Resources Administration of Greenland (Råstofforvaltningen for Grønland) on compilation of the mineral-exploration activity carried out in central East Greenland by Nordisk Mineselskab A/S during the period 1952- 1984. The main aim is to present geological descriptions of all known mineral occurrences and to compile most of the existing geochemical data in a manner applicable to future exploration in the area. More than 200 individual mineral occurrences are described and many in great detail. Geochemical data are presented for scheelite and for 16 elements relevant to the evaluation of the mineral potential of the area. The data are presented as single-element anomaly maps for both rock samples and panned heavy-mineral concentrates and include data from a file consisting of more than 10 000 rock samples and close to 4000 panned heavy-mineral samples.&#x0D; Mineralization in central East Greenland occurs in rocks of Archaean to Oligocene age and has tentatively been grouped into several periods when mineralization took place.&#x0D; Mineralization hosted in Archaean-Lower Proterozoic rocks includes magnetite and chromite accumulations and iron-sulphide segregations associated with ultramafic and mafic igneous assemblages, volcanogenic massive-sulphide occurrences, titaniferous magnetite and ilmenite occurrences associated with original plutonic anorthositic massifs, banded iron-formations, gold-bearing quartz veins, a complex copper-skarn occurrence, and uranium and gold-uranium occurrences of unknown origin.&#x0D; Mineralization hosted in Middle and Upper Proterozoic rocks is restricted to lead-zinc and tungsten skarns and stratiform copper occurrences.&#x0D; Mineralization hosted in Lower Palaeozoic rocks is in general believed to be associated with Caledonian orogenic activity. It comprises tungsten skarn occurrences mainly associated with granodiorite intrusions, base-metal and tungsten mineralization associated with late-kinematic probably calc-alkaline granite, tin-tungsten-arsenic quartz veins associated with late-kinematic probably mildly alkaline granites, gold-bearing quartz veins associated with late-kinematic granite, uraniferous veins in probably Devonian alkaline granite, tungsten-antimony-gold and silver-bearing base-metal veins in low-grade metamorphic sediments, uranium-fluorite veins in Devonian felsic volcanic rocks and strata-bound uranium occurrences hosted in Devonian elastic rocks.&#x0D; Mineralization hosted in Upper Palaeozoic sediments (Carboniferous - Permian) includes base-metal quartz-baryte veins locally enriched in precious metals, goldbearing quartz veins. uraniferous veins, carbonate-hosted strata-bound baryte base-metal occurrences, carbonate-hosted strata-bound celestite occurrences, stratiform base-metal showings of Kupferschiefer type and strata-bound red-bed copper occurrences.&#x0D; Mineralization hosted in Mesozoic sediments is represented by Triassic stratiform and strata-bound base-metal occurrences of red-bed type and Jurassic placers rich in zirconium and rare-earth elements.&#x0D; Tertiary mineralization includes a major porphyry-molybdenum occurrence, granite roof-zone molybdenum mineralization, niobium mineralization associated with alkaline intrusive rocks, lead-zinc skarn occurrences, a minor magnetite-skarn showing, lead-zinc-bearing quartz veins and precious-metal, base-metal, molybdenum and fluorite mineralization associated with fumarolic volcanic activity.&#x0D; The location of all mineral occurrences is shown on a separate map: Mineral Occurrences in Central East Greenland.