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Contribution to the Crystal Chemistry of Beryl

Sampaio Filho, H. de Almeida; Sighinolfi, G. P.; Galli, E. (Contributions to Mineralogy and Petrology, 1973)

Chemical analyses and crystallographic and some optical data have been obtained for 28 samples of beryl from Bahia State, Brazil. The larger range of variability in the chemical composition is sho~m by Mg, Fe and Li. Sodium ...
Thallium in deep-seated crustal rocks

Sighinolfi, G.Paolo; Santos, Adelaide M. (Geochimica et Cosmochimica Acta, 1974)

A Precambrian granulite terrain of the Brazilian shield presents an average Tl content of 350 ppb, very near to Shaw’s figure for the lower continental crust. Thallium, &8 in other rock types, shows close coherence with ...
Uranium and thorium in potash-rich rhyolites from western Bahia (Brazil)

Sighinolfi, G.Paolo; Sakai, Tereza (Chemical Geology, 1974)

The U and Th distribution in K-rich acid metavolcanics affected by postmagmatic processes has been studied. Th (20 ppm) and U (2.41 ppm) average abundances are well within the normal ranges for granitic rocks, but the Th/U ...
Petrology and Chemistry of Preeambrian Alkaline Rhyolites from Western Bahia (Brazil)

Sighinolfi, G. P.; Concegao, Theodora M. L. (Tschermaks Min. Petr. Mitt., 1975)

The petrology and chemistry of alkaline rhyolites from Western Bahia State are investigated. Original mineralogy and bulk chemistry are modified by secondary processes (cataclastic metamorphism, hydrothermal leaching). The ...
Geochemistry of gold in Archean granulite facies terrains

Sighinolfi, G.Paolo; Santos, Adelaide M. (Chemical Geology, 1976)

Gold distribution in Archean--Precambrian granulite facies terrains from Bahia state, Brazil, is investigated by means of flameless A.A. spectroscopy. The average Au content for 105 samples is 1.51 ppb, which is appreciably ...
Magnetotelluric Profiling of Vertical Conductors

Sampaio, E. S. (Pure and Applied Geophysics, 1976)

The presence of lateral contrasts of electrical conductivity modifies the original pattern of electromagnetic fields radiated from remote sources. A magnetic transverse plane wave field, interacting with a vertical conductive ...
Determination of Gold in Geological Samples at Parts Per Milliard Levels by Flameless Atomic-Absorption Spectroscopy

Sighinolfi, Gian Paolo; Santos, Adelaide M. (Microchimica ActaBrasil, 1976)
Determination of Cadmium in Silicate Materials by Flameless Atomic Absorption Spectroscopy

Sighinolfi, Gian Paolo; Santos, Adelaide M. (Microchimica ActaBrasil, 1976)
A note on the induced polarization of the bunter sandstone

Barker, R. D. (Geoexploration, 1976)

Laboratory investigations of the induced polarization of the Bunter Sandstone of northwest England have furnished values of frequency effect higher than those normally measured as the background effect in mineral surveys. ...
Resistivity surveys employed to study coastal aquifers in the state of Bahia, Brazil

Leite, J. L.; Barker, R. D. (Geoexploration, 1978)

Resistivity sounding surveys are currently employed by members of the Programa de Pesquisa e Posgraduação em Geofísica at the Federal University of Bahia, Brazil, in the study of groundwater problems. The tripotential ...
The chemistry of some Brazilian soils: Element mobility during intense weathering

Kronberg, B. I.; Fyfe, W. S.; Leonardos Junior, O. H.; Santos, A. M. (Chemical Geology, 1979)

Chemical data for 56 elements in soils from three regions of Brazil (Bahia, Amazon, Goias) indicate that intense chemical weathering leads to a product soil essentially in the system, SiO~--AI20 ~ --F%O3--H~O. The major ...
Determination of tellurium in geochemical materials by flameless atomic-absorption spectroscopy

Sighinolfi, G.Paolo; Santos, Adelaide M.; Martinelli, Giovanni (Talanta, 1979)

method is described for the determination of tellurium at nanogram levels in rocks and in other complex materials by the use of flameless atomic-absorption spectroscopy. A very selective organic extraction procedure is ...
Terrestrial heat flow in the tertiary basin of central Sumatra

Carvalho, Humberto Da Silva; Purwoko, Siswoyo; Thamrin, M.; Vacquier, Victor (Tectonophysics, 1980)

Heat flow at 170 locations in the Central Tertiary basin of Sumatra was determined from thermal gradients obtained from the extrapolated oil well bottom hole formation temperature and the assumed temperature of 80°F at the ...
Geochemistry and Petrology of the Jequie Granulitic Complex (Brazil): An Archean Basement Complex

Sighinolfi, G. P.; Figueredo, M. C. H.; Fyfe, W. S.; Kronberg, B. I.; Oliveira, M. A. F. Tanner (Contributions to Mineralogy and Petrology, 1981)

The Jequie granulitic complex is part of the extensive high-grade metamorphic terrain located within the Sao Francisco craton of northeastern Brazil. Some Jequie rocks appear to have been formed in the middle Archean (~3.1 ...
Brazil-Africa geological links

Torquato, Joaquim Raul; Cordani, Umberto G. (Earth-Science Reviews, 1981)

In this work, the main evidence and conclusions regarding geological links between Brazil and Africa are summarized, with emphasis on the geochronological aspects. Taking into account the geographical position, as well as ...
Effects of exponentially decaying spatial patterns on the probability distribution of anomalous values

Björklund, A. (Journal of Geochemical Exploration, 1983)

The nature of geochemical anomalies is discussed on a speculative basis. Anomalies are classified as independent or as additive, depending on their spatial relation to the background population. The additive anomalies, ...
Listric normal fault profiles: calculation using bed-length balance and fault displacement

Davison, Ian (Journal of Structural Geology, 1986)

A bed-length balance technique is presented to calculate listric normal fault trajectories using roll-over geometry and fault displacements. The technique can also be applied to subsidiary tistric normal fault fans above ...
Normal fault geometry related to sediment compaction and burial

Davison, Ian (Journal of Structural Geology, 1987)

Field observations are presented on meso-scale normal faults and sandstone dikes which cross-cut turbidites in the petroliferous Rec6ncavo Basin situated in Bahia, NE Brazil. Two discrete phases of normal faulting occurred. ...
Basement control and transfer tectonics in the Recôncavo-Tucano- Jatobá rift, Northeast Brazil

Davison, Ian; Milani, Edison José (1988)

The Reôncavo-Tucano-Jatobá rift consists of a series of asymmetric grabens which are separated by basement highs and transfer faults. Opening of the rift took place in a NW direction oblique to the N-S rift trend. Well ...
The rio Itapicuru greenstone belt, Bahia, Brazil: structure and stratigraphical outline

Davison, Ian; Teixeira, João Batista Guimarães; Silva, Maria da Gloria da; Rocha Neto, Manoel Barreto da; Matos, Fernando Martins Vieira (Precambrian Research, 1988)

The Rio Itapicuru greenstone belt is situated within the Silo Francisco craton, and is the largest of a series of N-S trending volcanosedimentary sequences surrounded by gneisses and granitoids. Pb-Pb and Rb-Sr dating of ...

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