The laser ablation technique, coupled with the use of quadrupole ICPMS equipment, proved a powerf... more The laser ablation technique, coupled with the use of quadrupole ICPMS equipment, proved a powerful tool for determination of trace elements in minerals. At the University of São Paulo, the technique was implemented for the study of minerals such as olivines, pyroxenes and biotites. The main problem to be tackled is the availability of proper multi-element reference materials usually prepared synthetically as glasses with various compositions by NIST and fused rock glasses by the Max Planck Institute (MPI) and USGS (basalts, andesite, quartz diorite, komatiites). The best tested ones are the NIST glasses, with good homogeneity and reliable compositional data for over 40 elements. Results are here presented that test additional RM's. NIST 612 and 610 were used for calibration purposes. The best results were obtained for rock glasses USGS basalts BHVO-2G, BIR-1G and BCR-2G (better homogeneity and recommended values). Our contribution tests especially the MPI komatiites glasses GOR-128 and GOR-132G, basalts KL-2G and ML-3BG, andesite StHs-6/ 80G and quartz diorite T-1G, discussing homogeneity issues and providing new data. There is a need for additional preparation of reliable reference materials.
ABSTRACT Quartz crystals from the Batatal site, Minas Gerais, southern Brazil, were used to deter... more ABSTRACT Quartz crystals from the Batatal site, Minas Gerais, southern Brazil, were used to determine quantitatively primary contamination when submitting the samples to milling processes. Crushing devices used were a primary steel jaw crusher (br1), a secondary tungsten carbide (WC) crusher (br2) and a hydraulic press with stainless steel plates (pr). Fragments with suitable sizes were then ground in different Fritsch planetary mills, equipped with agate, WC and chromium-steel rings for 7, 4 and 3 min respectively. Solutions of the powders were analysed initially with the TotalQuant™ method in a quadrupole ICP-MS instrument, providing semi-quantitative results for seventy-five elements. Contamination with crushers and mills were visible in major and minor elements such as Fe and Mn and Ti, and noticeable in trace elements such as Cr, Co, Ni, Cu, also V, Zr, Sc; significant contamination was observed with W, Mo, Co, and Ta and Nb (mainly by use of the WC devices). Little or no contamination was observed in Pb, REE, Sr and Rb, elements that are important in routine isotopic determinations. Cross contamination was tested grinding either a granite or a basalt sample, followed by conventional cleaning with mica-free quartz sand, before the working quartz powder was prepared.This article is protected by copyright. All rights reserved.
... Available online 12 March 2002. Abstract. The present contribution shows the results of tests... more ... Available online 12 March 2002. Abstract. The present contribution shows the results of tests on geological materials for determination of the rare-earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Y and Sc. ...
The Amazonian Craton comprises an Archean domain surrounded by four successively younger Proteroz... more The Amazonian Craton comprises an Archean domain surrounded by four successively younger Proterozoic tectonic provinces. Within the Rio-Negro-Juruena province the Serra da Providência Intrusive Suite (1.60 and 1.53 Ga) consists of A-type rapakivi granites, charnockites and mangerites genetically associated with diabase dikes, gabbros and amphibolites. The original mafic melts were derived from a depleted mantle source (! Nd(T) +2.5 to +2.8; ! Sr(T) -12.1). Underplated mafic magma induced melting of a short-lived felsic crust, thus originating coeval felsic-mafic magmatism in a continental intraplate setting. The Colorado Complex, assigned to the Rondonian-San Ignacio province, comprises 1.35-1.36 Ga intrusive bimodal magmatism represented by monzonite gneisses associated with amphibolite, gabbro and metadiabase dikes intercalated with metasediments with detrital zircon that yield U-Pb ages of 1.35 to 1.42 Ga. Mafic samples display juvenile signatures (! Nd(T) 0.0 to +5.2; ! Sr(T) -5.0 to -30.7) and are less contaminated than the Serra da Previdência and Nova Brasilândia ones. The generation of the basaltic magma is related to the subduction of an oceanic slab below the peridotite wedge (intraoceanic arc setting). Fluids and/or small melts from the slab impregnated the mantle. The Nova Brasilândia Sequence (Sunsas-Aguapeí province) comprises a metasedimentary sequence intruded by 1.10-1.02 Ga metadiabases, gabbros, meta-gabbros, and amphibolites associated with granitic plutons (bimodal magmatism). The original tholeiitic magmas, derived from a depleted source (! Nd(T) , in a proto-oceanic setting, underwent subsequent contamination by the host rocks, as indicated by the isotopic and trace element data.
The removal of Pb 2? from aqueous solution by two Brazilian rocks that contain zeolites-amygdaloi... more The removal of Pb 2? from aqueous solution by two Brazilian rocks that contain zeolites-amygdaloidal dacite (ZD) and sandstone (ZS)-was examined by batch experiments. ZD contains mordenite and ZS, stilbite. The effects of contact time, concentration of metal in solution and capacity of Na ? to recover the adsorbed metals were evaluated at room temperature (20°C). The sorption equilibrium was reached in the 30 min of agitation time. Both materials removed 100% of Pb 2? from solutions at concentrations up to 50 mg/L, and at concentrations larger than 100 mg/L of Pb 2? , the adsorption capacity of sandstone was more efficient than that of amygdaloidal dacite due to the larger quantities and the type of zeolites (stilbite) in the cement of this rock. All adsorbed Pb 2? was easily replaced by Na ? in both samples. The analysis of the adsorption models using nonlinear regression revealed that the Sips and the Freundlich isotherms provided the best fit for the ZS and ZD experimental data, respectively, indicating the heterogeneous adsorption surfaces of these zeolites.
Dentre os metais pesados existem aqueles classificados como essenciais (macro e micronutrientes),... more Dentre os metais pesados existem aqueles classificados como essenciais (macro e micronutrientes), contudo, são considerados tóxicos e perigosos à população e ao meio ambiente quando em concentrações relativamente elevadas.
... pulve-rizadas até a granulometria inferior a 200 mesh, respec-tivamente, em moinhos de ágata ... more ... pulve-rizadas até a granulometria inferior a 200 mesh, respec-tivamente, em moinhos de ágata e em ... Hernández MA, Corona L., Rojas F. 2000. ... Caracterização tecnológica das zeólitas naturais associadas às rochas eruptivas da Formação Serra Geral, na região de Piraju ...
The capacity of natural zeolites and its host rock (dacite) to remove Pb2+ and Cr3+ from aqueous ... more The capacity of natural zeolites and its host rock (dacite) to remove Pb2+ and Cr3+ from aqueous solutions has been investigated. Results showed that both samples prefer to remove Pb2+ instead of Cr3+. Almost 100% of Pb2+ was removed from solutions with concentration until 50 mg L-1 and 100 mg L-1 of this metal, respectively by dacite and zeolite. The equilibrium of metals adsorption process was reached during the first 30 min by both materials. Na+ can be used to recover Pb2+, but not to remove Cr3+ from the treated samples. The Sips model showed a good fit for experimental data of this study.
The determination of FeO of geologic materials by modern instrumental methods (such as atomic abs... more The determination of FeO of geologic materials by modern instrumental methods (such as atomic absorption spectroscopy (AAS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), etc.) cannot distinguish between different oxidation states of elements. In many cases, the oxidation state of Fe has to be known in order to perform several chemical calculations (norms, etc.) and discuss the
Zircon recrystallization is a common process during high-grade metamorphism and promotes partial ... more Zircon recrystallization is a common process during high-grade metamorphism and promotes partial or complete resetting of the original isotopic and chemical characteristics of the mineral and thus complicates U-Pb geochronological interpretation. In Central Brazil, this complexity may be illustrated by three composite mafic-ultramafic intrusions metamorphosed under amphibolite-to-granulite conditions. Their ages of emplacement and metamorphic ages have been a matter of controversy for the last thirty years. The Serra da Malacacheta and Barro Alto complexes make up the southernmost of these layered bodies and four samples from distinct rock types were investigated in order to verify the consequences of metamorphic alteration of zircon for U-Pb dating. Cathodoluminescent imaging reveals internal features which are typical of concomitant dissolution-reprecipitation processes, such as convolute zoning and inward-moving recrystallization fronts, even in samples in which partially preserved igneous textures are observed. Due to this extensive alteration, LA-ICPMS U-Pb isotopic analysis yielded inconclusive data. However, in situ Hf isotopic and trace-element analyses help to clarify the real meaning of the geochronological data. Low Lu/Hf (<0.004) and homogeneous 176 Hf/ 177 Hf t values imply that the zircon populations within individual samples have crystallized in a single episode, despite the observed variations in age values. Trace element signatures of zircon grains from garnet-bearing samples reveal that they were unreactive to the development of the peak metamorphism mineral assemblage and, thus, the main chemical feature in such grains is attributed to a coupled dissolution-reprecipitation process. However, in the Cafelândia amphibolite an additional alteration process is identified, probably related to the influx of late-stage fluids. Combined isotopic and geochemical investigation on zircon grains allowed the distinction of two magmatic events. The first corresponds to the crystallization of the Serra da Malacacheta Complex and characterizes a juvenile magmatism at ∼1.3 Ga. The younger episode, recognized in the Barro Alto Complex, is dated at ca. 800 Ma and is represented by mafic and ultramafic rocks showing intense contamination with continental crust, implying that the emplacement took place, most likely, in a continental back-arc setting. Altered zircon domains as well as titanite grains date the metamorphic event at ca. 760-750 Ma.
The contents of volatile elements in geological materials are usually determined by the non-selec... more The contents of volatile elements in geological materials are usually determined by the non-selective method of "loss of ignition" performed in a furnace at around 1000 °C, the results indicating the amounts of H 2 O + and CO 2 but also sulfur and other less abundant volatiles, such as Cl and F. The classical methods previously developed for the direct determination of H 2 O and CO 2 are tedious and very cumbersome (see references in Potts 1987; for historical background, see Thorburn Burns 1993).
The rare earth elements (REE), from lanthanum to lutetium, present similar physical and chemical ... more The rare earth elements (REE), from lanthanum to lutetium, present similar physical and chemical properties as a result of their particular electronic configurations. In spite of their similar behaviour these elements can be fractionated by a number of geological processes, depending on small differences in their ionic size in relation to the large number of coordination sites that exist in minerals. Interest in the geochemical behaviour of REE has increased steadily in the last few decades, since their occurrence and degree of fractionation can be a valuable tool in the interpretation of geological processes. At the same time, recent Vol. 32 -N°2 p . 1 6 7 -1 8 0 Tests are described showing the results obtained for the determination of REE and the trace elements Rb, Y, Zr, Nb, Cs, Ba, Hf, Ta, Pb, Th and U with ICP-MS methodology for nine basaltic reference materials, and thirteen basalts and amphibolites from the mafic-ultramafic Niquelândia Complex, central Brazil. Sample decomposition for the reference materials was performed by microwave oven digestion (HF and HNO 3 , 100 mg of sample), and that for the Niquelândia samples also by Parr bomb treatment (5 days at 200 °C, 40 mg of sample). Results for the reference materials were similar to published values, thus showing that the microwave technique can be used with confidence for basaltic rocks. No fluoride precipitates were observed in the microwave-digested solutions. Total recovery of elements, including Zr and Hf, was obtained for the Niquelândia samples, with the exception of an amphibolite. For this latter sample, the Parr method achieved a total digestion, but not so the microwave decomposition; losses, however, were observed only for Zr and Hf, indicating difficulty in dissolving Zr-bearing minerals by microwave acid attack.
The laser ablation technique, coupled with the use of quadrupole ICPMS equipment, proved a powerf... more The laser ablation technique, coupled with the use of quadrupole ICPMS equipment, proved a powerful tool for determination of trace elements in minerals. At the University of São Paulo, the technique was implemented for the study of minerals such as olivines, pyroxenes and biotites. The main problem to be tackled is the availability of proper multi-element reference materials usually prepared synthetically as glasses with various compositions by NIST and fused rock glasses by the Max Planck Institute (MPI) and USGS (basalts, andesite, quartz diorite, komatiites). The best tested ones are the NIST glasses, with good homogeneity and reliable compositional data for over 40 elements. Results are here presented that test additional RM's. NIST 612 and 610 were used for calibration purposes. The best results were obtained for rock glasses USGS basalts BHVO-2G, BIR-1G and BCR-2G (better homogeneity and recommended values). Our contribution tests especially the MPI komatiites glasses GOR-128 and GOR-132G, basalts KL-2G and ML-3BG, andesite StHs-6/ 80G and quartz diorite T-1G, discussing homogeneity issues and providing new data. There is a need for additional preparation of reliable reference materials.
ABSTRACT Quartz crystals from the Batatal site, Minas Gerais, southern Brazil, were used to deter... more ABSTRACT Quartz crystals from the Batatal site, Minas Gerais, southern Brazil, were used to determine quantitatively primary contamination when submitting the samples to milling processes. Crushing devices used were a primary steel jaw crusher (br1), a secondary tungsten carbide (WC) crusher (br2) and a hydraulic press with stainless steel plates (pr). Fragments with suitable sizes were then ground in different Fritsch planetary mills, equipped with agate, WC and chromium-steel rings for 7, 4 and 3 min respectively. Solutions of the powders were analysed initially with the TotalQuant™ method in a quadrupole ICP-MS instrument, providing semi-quantitative results for seventy-five elements. Contamination with crushers and mills were visible in major and minor elements such as Fe and Mn and Ti, and noticeable in trace elements such as Cr, Co, Ni, Cu, also V, Zr, Sc; significant contamination was observed with W, Mo, Co, and Ta and Nb (mainly by use of the WC devices). Little or no contamination was observed in Pb, REE, Sr and Rb, elements that are important in routine isotopic determinations. Cross contamination was tested grinding either a granite or a basalt sample, followed by conventional cleaning with mica-free quartz sand, before the working quartz powder was prepared.This article is protected by copyright. All rights reserved.
... Available online 12 March 2002. Abstract. The present contribution shows the results of tests... more ... Available online 12 March 2002. Abstract. The present contribution shows the results of tests on geological materials for determination of the rare-earth elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Y and Sc. ...
The Amazonian Craton comprises an Archean domain surrounded by four successively younger Proteroz... more The Amazonian Craton comprises an Archean domain surrounded by four successively younger Proterozoic tectonic provinces. Within the Rio-Negro-Juruena province the Serra da Providência Intrusive Suite (1.60 and 1.53 Ga) consists of A-type rapakivi granites, charnockites and mangerites genetically associated with diabase dikes, gabbros and amphibolites. The original mafic melts were derived from a depleted mantle source (! Nd(T) +2.5 to +2.8; ! Sr(T) -12.1). Underplated mafic magma induced melting of a short-lived felsic crust, thus originating coeval felsic-mafic magmatism in a continental intraplate setting. The Colorado Complex, assigned to the Rondonian-San Ignacio province, comprises 1.35-1.36 Ga intrusive bimodal magmatism represented by monzonite gneisses associated with amphibolite, gabbro and metadiabase dikes intercalated with metasediments with detrital zircon that yield U-Pb ages of 1.35 to 1.42 Ga. Mafic samples display juvenile signatures (! Nd(T) 0.0 to +5.2; ! Sr(T) -5.0 to -30.7) and are less contaminated than the Serra da Previdência and Nova Brasilândia ones. The generation of the basaltic magma is related to the subduction of an oceanic slab below the peridotite wedge (intraoceanic arc setting). Fluids and/or small melts from the slab impregnated the mantle. The Nova Brasilândia Sequence (Sunsas-Aguapeí province) comprises a metasedimentary sequence intruded by 1.10-1.02 Ga metadiabases, gabbros, meta-gabbros, and amphibolites associated with granitic plutons (bimodal magmatism). The original tholeiitic magmas, derived from a depleted source (! Nd(T) , in a proto-oceanic setting, underwent subsequent contamination by the host rocks, as indicated by the isotopic and trace element data.
The removal of Pb 2? from aqueous solution by two Brazilian rocks that contain zeolites-amygdaloi... more The removal of Pb 2? from aqueous solution by two Brazilian rocks that contain zeolites-amygdaloidal dacite (ZD) and sandstone (ZS)-was examined by batch experiments. ZD contains mordenite and ZS, stilbite. The effects of contact time, concentration of metal in solution and capacity of Na ? to recover the adsorbed metals were evaluated at room temperature (20°C). The sorption equilibrium was reached in the 30 min of agitation time. Both materials removed 100% of Pb 2? from solutions at concentrations up to 50 mg/L, and at concentrations larger than 100 mg/L of Pb 2? , the adsorption capacity of sandstone was more efficient than that of amygdaloidal dacite due to the larger quantities and the type of zeolites (stilbite) in the cement of this rock. All adsorbed Pb 2? was easily replaced by Na ? in both samples. The analysis of the adsorption models using nonlinear regression revealed that the Sips and the Freundlich isotherms provided the best fit for the ZS and ZD experimental data, respectively, indicating the heterogeneous adsorption surfaces of these zeolites.
Dentre os metais pesados existem aqueles classificados como essenciais (macro e micronutrientes),... more Dentre os metais pesados existem aqueles classificados como essenciais (macro e micronutrientes), contudo, são considerados tóxicos e perigosos à população e ao meio ambiente quando em concentrações relativamente elevadas.
... pulve-rizadas até a granulometria inferior a 200 mesh, respec-tivamente, em moinhos de ágata ... more ... pulve-rizadas até a granulometria inferior a 200 mesh, respec-tivamente, em moinhos de ágata e em ... Hernández MA, Corona L., Rojas F. 2000. ... Caracterização tecnológica das zeólitas naturais associadas às rochas eruptivas da Formação Serra Geral, na região de Piraju ...
The capacity of natural zeolites and its host rock (dacite) to remove Pb2+ and Cr3+ from aqueous ... more The capacity of natural zeolites and its host rock (dacite) to remove Pb2+ and Cr3+ from aqueous solutions has been investigated. Results showed that both samples prefer to remove Pb2+ instead of Cr3+. Almost 100% of Pb2+ was removed from solutions with concentration until 50 mg L-1 and 100 mg L-1 of this metal, respectively by dacite and zeolite. The equilibrium of metals adsorption process was reached during the first 30 min by both materials. Na+ can be used to recover Pb2+, but not to remove Cr3+ from the treated samples. The Sips model showed a good fit for experimental data of this study.
The determination of FeO of geologic materials by modern instrumental methods (such as atomic abs... more The determination of FeO of geologic materials by modern instrumental methods (such as atomic absorption spectroscopy (AAS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), etc.) cannot distinguish between different oxidation states of elements. In many cases, the oxidation state of Fe has to be known in order to perform several chemical calculations (norms, etc.) and discuss the
Zircon recrystallization is a common process during high-grade metamorphism and promotes partial ... more Zircon recrystallization is a common process during high-grade metamorphism and promotes partial or complete resetting of the original isotopic and chemical characteristics of the mineral and thus complicates U-Pb geochronological interpretation. In Central Brazil, this complexity may be illustrated by three composite mafic-ultramafic intrusions metamorphosed under amphibolite-to-granulite conditions. Their ages of emplacement and metamorphic ages have been a matter of controversy for the last thirty years. The Serra da Malacacheta and Barro Alto complexes make up the southernmost of these layered bodies and four samples from distinct rock types were investigated in order to verify the consequences of metamorphic alteration of zircon for U-Pb dating. Cathodoluminescent imaging reveals internal features which are typical of concomitant dissolution-reprecipitation processes, such as convolute zoning and inward-moving recrystallization fronts, even in samples in which partially preserved igneous textures are observed. Due to this extensive alteration, LA-ICPMS U-Pb isotopic analysis yielded inconclusive data. However, in situ Hf isotopic and trace-element analyses help to clarify the real meaning of the geochronological data. Low Lu/Hf (<0.004) and homogeneous 176 Hf/ 177 Hf t values imply that the zircon populations within individual samples have crystallized in a single episode, despite the observed variations in age values. Trace element signatures of zircon grains from garnet-bearing samples reveal that they were unreactive to the development of the peak metamorphism mineral assemblage and, thus, the main chemical feature in such grains is attributed to a coupled dissolution-reprecipitation process. However, in the Cafelândia amphibolite an additional alteration process is identified, probably related to the influx of late-stage fluids. Combined isotopic and geochemical investigation on zircon grains allowed the distinction of two magmatic events. The first corresponds to the crystallization of the Serra da Malacacheta Complex and characterizes a juvenile magmatism at ∼1.3 Ga. The younger episode, recognized in the Barro Alto Complex, is dated at ca. 800 Ma and is represented by mafic and ultramafic rocks showing intense contamination with continental crust, implying that the emplacement took place, most likely, in a continental back-arc setting. Altered zircon domains as well as titanite grains date the metamorphic event at ca. 760-750 Ma.
The contents of volatile elements in geological materials are usually determined by the non-selec... more The contents of volatile elements in geological materials are usually determined by the non-selective method of "loss of ignition" performed in a furnace at around 1000 °C, the results indicating the amounts of H 2 O + and CO 2 but also sulfur and other less abundant volatiles, such as Cl and F. The classical methods previously developed for the direct determination of H 2 O and CO 2 are tedious and very cumbersome (see references in Potts 1987; for historical background, see Thorburn Burns 1993).
The rare earth elements (REE), from lanthanum to lutetium, present similar physical and chemical ... more The rare earth elements (REE), from lanthanum to lutetium, present similar physical and chemical properties as a result of their particular electronic configurations. In spite of their similar behaviour these elements can be fractionated by a number of geological processes, depending on small differences in their ionic size in relation to the large number of coordination sites that exist in minerals. Interest in the geochemical behaviour of REE has increased steadily in the last few decades, since their occurrence and degree of fractionation can be a valuable tool in the interpretation of geological processes. At the same time, recent Vol. 32 -N°2 p . 1 6 7 -1 8 0 Tests are described showing the results obtained for the determination of REE and the trace elements Rb, Y, Zr, Nb, Cs, Ba, Hf, Ta, Pb, Th and U with ICP-MS methodology for nine basaltic reference materials, and thirteen basalts and amphibolites from the mafic-ultramafic Niquelândia Complex, central Brazil. Sample decomposition for the reference materials was performed by microwave oven digestion (HF and HNO 3 , 100 mg of sample), and that for the Niquelândia samples also by Parr bomb treatment (5 days at 200 °C, 40 mg of sample). Results for the reference materials were similar to published values, thus showing that the microwave technique can be used with confidence for basaltic rocks. No fluoride precipitates were observed in the microwave-digested solutions. Total recovery of elements, including Zr and Hf, was obtained for the Niquelândia samples, with the exception of an amphibolite. For this latter sample, the Parr method achieved a total digestion, but not so the microwave decomposition; losses, however, were observed only for Zr and Hf, indicating difficulty in dissolving Zr-bearing minerals by microwave acid attack.
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