Firing Tests on Clay-Rich Raw Materials from the Algarve Basin (Southern Portugal): Study of Mineral Transformations with Temperature

2010 ◽  
Vol 58 (2) ◽  
pp. 188-204 ◽  
Author(s):  
Maria José Trindade ◽  
Maria Isabel Dias ◽  
João Coroado ◽  
Fernando Rocha
Keyword(s):  
Raw Materials ◽  
Southern Portugal ◽  
Algarve Basin ◽  
Mineral Transformations ◽  
Firing Tests

Constraining the age of the first pulse of continental rifting associated with the breakup of Pangea in Southwest Iberia

2021 ◽  
Author(s):  
Margarida Vilas-Boas ◽  
Niall W. Paterson ◽  
Zélia Pereira ◽  
Paulo Fernandes ◽  
Simonetta Cirilli
Keyword(s):  
Financial Support ◽  
Depositional Environment ◽  
Late Triassic ◽  
The North ◽  
Low Diversity ◽  
Southern Portugal ◽  
Palynological Study ◽  
Algarve Basin ◽  
Central Atlantic ◽  
Red Bed

<p>The Algarve Basin is a Mesozoic sedimentary basin located in southern Portugal. The basin was initiated by rifting associated with the opening of the North and Central Atlantic Ocean during the initial breakup of Pangea. Sedimentation commenced with continental red beds, which unconformably overlie folded and faulted late Carboniferous strata. The red bed succession (Silves Sandstones) consists mainly of sandstones and conglomerates at the base, overlain by variegated mudstones interbedded with siltstones and dolomites (Silves Mudstones, Siltstones and Dolomites). The sandstones were deposited in alluvial environments, and the mudstones in alluvial to shallow lacustrine environments. Upper Triassic (Carnian to Norian) macrofossils are scarce in the red bed succession, occurring predominantly in the upper beds of the succession above the Silves Sandstones, and do not accurately constrain the age of the beginning of the Algarve Basin.</p><p>A palynological study of a new road cut outcrop of Silves Sandstones, located in central Algarve, was undertaken in order to ascertain its age. A 3 m thick bed of grey siltstones located ca. 2.5 m above the unconformity yielded age-diagnostic palynomorphs, which date the onset of sedimentation in the basin. Samples from the latter bed yielded a moderately well preserved, low diversity palynomorph assemblage, which is dominated by <em>Aulisporites astigmosus, Converrucosisporites</em> sp. and <em>Tulesporites briscoensis</em>. Other taxa present in the assemblage include <em>Alisporites</em> sp., <em>Calamospora</em> sp., <em>Cycadopites</em> sp., <em>Deltoidospora</em> sp., <em>Ovalipollis</em> cf. <em>ovalis</em>, <em>Triadispora</em> sp., and <em>Vallasporites ignacii</em>.</p><p>The dominance of <em>A. astigmosus</em> together with <em>V. ignacii</em> is indicative of an early Carnian age based on comparison with independently dated sections described elsewhere in Europe. This new dating evidence thus constrains the beginning of sedimentation in the Algarve Basin to the earliest Late Triassic. The co-occurrence of <em>T. briscoensis</em> and <em>A. astigmosus</em> suggests a mixing of palynofloral elements typical of North American and central European Carnian assemblages respectively, which is consistent with the intermediate position of Portugal between those regions. The dominance of phytoclasts and the absence of marine palynomorphs confirms a continental depositional environment as also suggested by sedimentary lithofacies.</p><p><strong>Acknowledgements</strong></p><p>The authors would like to acknowledge the financial support of the Portuguese Foundation of Science and Technology (FCT) with the scholarship with the reference SFRH/BD/144125/2019 and would also like to acknowledge the financial support of the FCT to CIMA through UIDP/00350/2020.</p>

scholarly journals Analytical investigation of archaeological pottery fragments excavated from Porunthal, Tamil Nadu, India

Cerâmica ◽  
2020 ◽  
Vol 66 (379) ◽  
pp. 347-353
Author(s):  
G. Raja Annamalai ◽  
R. Ravisankar ◽  
A. Chandrasekaran
Keyword(s):  
Tamil Nadu ◽  
Raw Materials ◽  
Energy Dispersive Spectrometer ◽  
Analytical Data ◽  
Archaeological Site ◽  
Analytical Investigation ◽  
X Ray Diffraction ◽  
Pottery Production ◽  
Technological Study ◽  
Mineral Transformations

Abstract Within the framework of a technological study of pottery production of Porunthal, Dindigul district of Tamil Nadu, India, the chemical composition and mineralogy of the 7 potteries of different varieties from that archaeological site were studied using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), and scanning electron microscopy coupled with energy dispersive spectrometer (SEM-EDS). The analytical data obtained from several analyses were used to determine the mineral transformations during firing, such as quartz, feldspar, and iron oxides (hematite and magnetite), firing temperature, and firing conditions. The results of all the techniques confirmed that all the samples were manufactured by the artisans locally with the same raw materials and also were fired at the same temperature.

Organic maturation of the Algarve Basin (southern Portugal) and its bearing on thermal history and hydrocarbon exploration

2013 ◽  
Vol 46 ◽  
pp. 210-233 ◽  
Author(s):  
Paulo Fernandes ◽  
Bruno Rodrigues ◽  
Marisa Borges ◽  
Vasco Matos ◽  
Geoff Clayton
Keyword(s):  
Thermal History ◽  
Hydrocarbon Exploration ◽  
Southern Portugal ◽  
Algarve Basin

scholarly journals The Jurassic (Pliensbachian to Kimmeridgian) palynology of the Algarve Basin and the Carrapateira outlier, southern Portugal

2011 ◽  
Vol 163 (3-4) ◽  
pp. 190-204 ◽  
Author(s):  
Marisa E.N. Borges ◽  
James B. Riding ◽  
Paulo Fernandes ◽  
Zélia Pereira
Keyword(s):  
Southern Portugal ◽  
Algarve Basin

scholarly journals Presenting LusoLit: A lithotheque of knappable raw materials from central and southern Portugal

2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Telmo Pereira ◽  
Anne Farias ◽  
Eduardo Paixão
Keyword(s):  
Decision Making ◽  
Cognitive Abilities ◽  
Raw Materials ◽  
Early Stage ◽  
Human Behaviour ◽  
Raw Material ◽  
Human Populations ◽  
Archaeological Record ◽  
Human Decision ◽  
Southern Portugal

The knowledge of where past human populations collected their raw materials to produce stone-tools is crucial to understand subjects such as their territoriality, mobility, decision-making, range of acquisition, networks and, eventually, to infer their cognitive abilities and the adaptations to new environments, landscapes and territories. Therefore, the creation of lithic reference collections (lithotheque) is of utmost importance.In geological terms, Portugal is a highly complex and diversified region, with a plethora of igneous, sedimentary and metamorphic rocks dated from Proterozoic to present days. Such diversity might have influenced considerably the human decision-making on the choices of raw material and it might be one of the major reasons for the diversity seen throughout the diachrony of its archaeological record. Thus, sampling, cataloguing and mapping the raw material diversity in a territory with such variability allows to enrich the knowledge about it and, consequently to build stronger inferences about past human behaviour with more detail and less bias.In order to help the archaeological and anthropological research to better understand such archaeological record and past human behaviour in this territory, we started a reference collection for this region host in the University of Algarve: the LusoLit. Though in its early stages, this collection has already several hundred chert samples from Central and Southern Portugal. In this early stage, the raw material that we start collecting was chert because it is the least ubiquitous through the landscape and, consequently, that can provide better information. 

scholarly journals Callovian (Middle Jurassic) dinoflagellate cysts from the Algarve Basin, southern Portugal

2012 ◽  
Vol 170 ◽  
pp. 40-56 ◽  
Author(s):  
Marisa E.N. Borges ◽  
James B. Riding ◽  
Paulo Fernandes ◽  
Vasco Matos ◽  
Zélia Pereira
Keyword(s):  
Middle Jurassic ◽  
Dinoflagellate Cysts ◽  
Southern Portugal ◽  
Algarve Basin

scholarly journals Clayey materials from the Sierra de la Demanda Range (Spain): their potential as raw materials for the building ceramics industry

Clay Minerals ◽  
2005 ◽  
Vol 40 (1) ◽  
pp. 25-41 ◽  
Author(s):  
R. Artigas ◽  
M. Rodas ◽  
C. J. Sánchez ◽  
R. Mas ◽  
M. Dondi ◽  
...  
Keyword(s):  
Raw Materials ◽  
Clay Mineralogy ◽  
Mineralogical Composition ◽  
Raw Material ◽  
Clay Deposits ◽  
Ceramic Articles ◽  
Ceramics Industry ◽  
Firing Tests ◽  
Good Behaviour ◽  
Clayey Materials

AbstractThis work describes the possible use of thick Early Cretaceous clay deposits, which occur in the southern sector of the Sierra de la Demanda range, as raw materials in the manufacture of ceramic articles. The global mineralogical composition is characterized by high proportions of phyllosilicates and quartz with variable quantities of feldspars, carbonates and hematite. The clay mineralogy differentiates two types of raw materials: illitic clay and kaolinitic-illitic clay. A granulometric distribution in the 2–60 µm fraction, good behaviour during the drying stage and acceptable results in firing tests confirmed that most samples can be utilized as raw material in the building ceramics industry. The range of suitable firing temperatures for these materials is 950–1000°C, a temperature which needs to be raised for samples with a high percentage of kaolinite and quartz. Moreover, other materials with abundant calcite (20–30%) are suitable for use as modifiers of some properties or colour.

Loulé: the anatomy of a squeezed diapir, Algarve Basin, southern Portugal

2016 ◽  
Vol 174 (1) ◽  
pp. 41-55 ◽  
Author(s):  
Ian Davison ◽  
Pedro Barreto ◽  
Alexandre J. M. Andrade
Keyword(s):  
Southern Portugal ◽  
Algarve Basin

Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

1988 ◽  
Vol 46 ◽  
pp. 582-583
Author(s):  
C. J. Chan ◽  
K. R. Venkatachari ◽  
W. M. Kriven ◽  
J. F. Young
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Shape Change ◽  
Microstructural Characterization ◽  
Particle Size Effect ◽  
Dicalcium Silicate ◽  
Laser Melting ◽  
Uniform Size ◽  
Cell Shape Change ◽  
Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

Crystallization of barium hexaferrite

1992 ◽  
Vol 50 (1) ◽  
pp. 362-363
Author(s):  
Chung-kook Lee ◽  
Yolande Berta ◽  
Robert F. Speyer
Keyword(s):  
Size Distribution ◽  
Raw Materials ◽  
Barium Hexaferrite ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Promising Candidate ◽  
Crystallization Method ◽  
Temperature Heat ◽  
High Density Magnetic Recording ◽  
Temperature Heat Treatment

Barium hexaferrite (BaFe12O19) is a promising candidate for high density magnetic recording media due to its superior magnetic properties. For particulate recording media, nano-sized single crystalline powders with a narrow size distribution are a primary application requirement. The glass-crystallization method is preferred because of the controllability of crystallization kinetics, hence, particle size and size distribution. A disadvantage of this method is the need to melt raw materials at high temperatures with non-reactive crucibles, e.g. platinum. However, in this work, we have shown that crystal growth of barium hexaferrite occurred during low temperature heat treatment of raw batches.

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