Bean Grain Research Articles

Technological quality of common bean grains obtained in different growing seasons

The traits that provide technological quality to common bean grains exhibit genetic and environmental variation and variation in the genotype x environment interaction. In this context, the aim of this study was to assess the effect of different periods of the growing season on the technological quality of common bean grains. The experiment was conducted with 25 bean genotypes (carioca [beige with brown stripes] and black commercial group) that are part of the Value for Cultivation and Use (Valor de Cultivo e Uso - VCU) trials in three growing seasons, namely, the 2009/2010 rainy season, the 2010/2011 dry season and the 2010/2011 winter season, in a randomized block experimental design with three replications in which the following items were assessed: cooking time (CT), water absorption capacity before cooking (Peanc) and after cooking (Peapc), percentage of whole grains (PWG), total soluble solids in the broth (TSSb), volume expansion before cooking (EXPVbc) and after cooking (EXPVac), and dry grain density (DD), grain density after maceration (SD) and grain density after cooking (CD). Assessments showed that the different growing seasons for obtaining grains for the purpose of analysis of technological quality have an effect on the results and on differentiation among genotypes, indicating genotype x environment interaction. They also showed that the genotypes C2-1-6-1, C4-8-1-1, LP04-03, IAC-Imperador, P5-4-4-1 and Pr11-6-4-1-2 had the best results in relation to cooking time in the mean values of the three growing seasons. The use of early selection based on phenotypic correlations that exist among the technological features is not expressive, due to the variation of magnitude among the different growing seasons.

Chemical composition of three cultivars of Brazilian beans

Brazil is one of the largest producers and consumers of beans. The grains of beans fill the main dietary recommendations for good health because it provides essential nutrients. In this study, we selected different varieties of beans as IPR88 Uirapuru (Uirapuru), BRS Jalo (Jalo) and BRS Radiante (Cavalo), and compared the chemical composition of raw beans. The samples (10 Kg of each cultivar) were collected in 2012, February (Jalo and Cavalo: latitude -26º 8’ 46.78’’; longitude -52º 41’ 44.78’’) and March (Uirapuru: latitude -26º 7’ 30.79’’; longitude -52º 38’ 57.31’’) at Pato Branco, Paraná state, Brazil. The physicochemical parameters (lipids, crude protein, fixed mineral residue, humidity, carbohydrates), and minerals content followed the methods described by AOAC. All the analysis was made in triplicate. The mineral composition of the three cultivars studied presented values closed to each other, but IPR88 Uirapuru was distinguished by a greater protein value and a higher amount of calcium and phosphorus. The centesimal composition of the three varieties presented values closed to each other, distinguished BRS Jalo with higher content of fiber. The physical chemical composition showed that they become an excellent raw material for bakery industry and could be used for the development of specific food products.

REMOTE SENSING AS AN INDIRECT WAY TO ESTIMATE BIOPHYSICAL AND BIOCHEMICAL PROPERTIES OF BEANS CROP

Non-destructive monitoring of agricultural crops becomes more important to improve crop productivity. In site specific management, in-situ remotely sensed data is of significant importance for quantifying nitrogen deficiency and salinity stress effects on crops. In the reported research, the visible and near infrared portions of the electromagnetic spectrum were used to derive vegetation indices sensitive to nitrogen deficiency and salinity stress in beans (Phaseolus Vulgaris, L). Four nitrogen fertilization rates (0, 30, 60 and 100 kg/ha) and three water salinity levels (1.5, 3 and 5 dS/m) were used to subject plants to both stressors. Reflectance measurements were collected from beans plants under artificial illumination conditions at different growth stages and used to calculate 45 commonly used vegetation indices for predicting beans properties. Strong significant correlations between beans properties and different vegetation indices were observed. Crededge and R750/R700 ratio were found to be the optimum indices for predicting beans chlorophyll content (r = 0.657). R710/R760 ratio was also found to be the optimum index for predicting beans biomass (r = -0.582). PSNDb was found to be sensitive to beans grain yield (r > 0.595). The correlations with grain yield were found to be strongest at the R6 growth stage.

Soil physical attributes in integrated bean and sheep system under nitrogen levels

Integrated crop-livestock systems (ICLS) can promote higher grain and meat/milk yield as well as reduce soil degradation risks. Thus, this study aimed to evaluate the influence of grazing sheep with moderate intensity and nitrogen doses on soil physical attributes, and bean crop yield (Phaseolus vulgaris Lam.) under rotation with summer corn crop (Zea mays Lam.) and winter pasture with oats (Avena sativa Lam) and ryegrass (Lolium multiflorum Lam.) The experimental design was completely randomized blocks with split-plot; the plots were nitrogen doses and the split-plots were grazing presence or absence. The treatments were nitrogen doses of 0, 75, 150 and 225 kg ha-1 applied on ryegrass and white oat pasture in winter followed by bean crop. Soil density, macroporosity, microporosity and total porosity and bean grain yield were evaluated. When ICLS are managed under no-tillage with moderate grazing, sheep trampling did not affect negatively soil physical attributes, which did not reach critical levels for subsequent growth and development of the bean crop. The black bean yield in summer was not affected by antecedent presence of sheep grazing in winter.

Genetic control and estimation of genetic parameters for seed-coat darkening of carioca beans.

The maintenance of the light color of the grains of carioca beans is a requirement for the development of new cultivars of common beans because it enables the storage of grains for long periods so that they may be traded at a proper opportunity. Crosses of cultivar BRSMG Madrepérola, which presents slow grain darkening, were made to 10 elite lines presenting normal darkening to obtain information about the genetic control of the trait and estimates of phenotypic and genotypic parameters. Progenies at the tegument generations F3 and F4 and their parents were evaluated at the locations of Santo Antônio de Goiás and Ponta Grossa at 71, 106, and 155 days of storage for seed-coat darkening using a rank of scores ranging from 1 (very light colored grains) to 5 (very dark colored grains). Genotypic and phenotypic variances and broad-sense heritabilities were estimated for each population. The segregation ratios were subjected to the chi-square test to establish the genetic control. Some populations did not present consistent patterns of genetic control, while others presented monogenic or double-recessive digenic segregation, indicating that the trait is controlled by few genes. Six segregant populations were identified with both low means for darkening and high expected gain under selection. Despite the strong environmental influence on the expression of the traits and the occurrence of the genotype by environment interaction, the estimates of genotypic and phenotypic parameters indicate the possibility of successful selection to develop lines with slow seed-coat darkening.

NITROGEN USE EFFICIENCY IN DRY BEAN GENOTYPES

Dry bean is an important legume crop for Latin American people and nitrogen is one of the most yields limiting nutrients for bean crop. A greenhouse experiment was conducted to evaluate nitrogen (N) use efficiency of 20 dry bean genotypes. Genotypes were grown on an Oxisol and two N levels used were without N application (low level) and an application of 400 mg N kg−1 (high level). Shoot dry weight, grain yield and yield components, N concentration and uptake in shoot and grain were significantly affected by N and genotype treatments. Grain yield had a highly significant (P < 0.01) association with shoot dry weight, pod number, grains per pod and 100 grain weight. Among the 20 genotypes tested, Perola, CNFR 7847, CNFR 7865, CNFP 7777 and CNFM 6911 were found to produce reasonably good yield at low N rate as well as responded well to applied N. Whereas, some genotypes like BRS Radiante, CNFP 7624, CNFM 7875, CNFM 7886, CNFC 7813, CNFC 7827, CNFP 7677 and CNFP 7775 produced very good yields at higher N rate but very low yields at lower N rate. Hence, these genotypes are good for farmers using higher technology. Nitrogen concentration and uptake were higher in dry bean grains compared with shoot and 63% of N accumulated at zero N rate and 75% N accumulated at 400 mg N rate were translocated to grain across 20 genotypes. Nitrogen uptake efficiencies were having highly significant (P < 0.01) quadratic relationship with grain yield. This indicates that improving N uptake in dry bean plants can increase grain yield.

Physico-chemical properties of common beans under natural and accelerated storage conditions

The common bean is an important food in the human diet. Certain storage conditions, high temperatures and high humidity, cause a texture defect that reduces the acceptability of common beans. The present study aimed at evaluating the effect of storage on the physico-chemical properties of common bean grains and the relationship between accelerated aging at 40 °C and 76% RH and storage under natural conditions. Two varieties of common beans (Iapar 81 – carioca variety and Iapar 44 – black variety) were stored at 40 oC and 76% RH for 15, 30, 45, 60 and 75 days to accelerate aging. The same varieties were stored under environmental conditions (natural aging) for 3, 6, 9 and 12 months. For both storage conditions of each variety, fresh beans stored at 5 oC were used as a control group. In all of the samples, hardness, pH, acidity and the soluble protein percentage were analyzed. Both storage processes, in the natural and accelerated conditions, caused an increase in acidity (4.0 to 5.9 and 3.2 to 6.4 g acetic acid kg -1 ) and a decrease in cellular pH (6.65 to 6.45 and 6.65 to 6.45) and protein solubility (77 to 54 and 76 to 38%). The greatest percentage changes in the parameters of acidity, pH and soluble proteins were observed in the beans in the accelerated aging condition. Beans’ hardness during storage has a negative correlation with pH, which shows that it is a good indicator of grain quality. Natural storage for one year is equivalent to accelerated aging for 45 days at 40 °C and 76% RH. El frijol es un alimento importante en la dieta humana, cuyas condiciones de almacenamiento de alta temperatura y humedad provocan un defecto textural que reduce la aceptabilidad del frijol. El presente estudio tiene como objetivo evaluar el efecto de los metodos de almacenamiento a las propiedades fisicoquimicas de los granos de frijol comun y la relacion entre la aceleracion del envejecimiento a 40 °C y 76% humedad relativa (HR) y el almacenamiento en condiciones naturales. Se almacenaron dos variedades de frijol comun (IAPAR 81 - carioca variedad y IAPAR 44 - la variedad negro) a 40 oC y 76% HR durante 15, 30, 45, 60, 75 dias de envejecimiento acelerado. Las mismas variedades fueron almacenadas bajo condiciones ambientales (envejecimiento natural) durante 3, 6, 9 y 12 meses. Para ambas condiciones de almacenamiento de cada variedad, se almacenaron granos nuevos a 5 oC, los que se consideraron como control. En todas las muestras, se analizo dureza, pH, acidez y porcentaje de proteina soluble. En ambos almacenamientos se observo un aumento de la acidez (4.0 a 5.9 y 3.2 a 6.4 g de acido acetico kg -1 ) y una reduccion del pH celular (6.65 a 6.45 y 6.65 a 6.45) y solubilidad de la proteina (77 a 54 y 76 a 38%), para las condiciones naturales y acelerada, respectivamente. Los mayores cambios en los parametros del porcentaje de acidez, pH y proteinas solubles se observaron en el frijol en el envejecimiento acelerado. La dureza de los granos durante el almacenamiento tiene una correlacion negativa con el pH, lo que senala que este es un buen indicador de la calidad del grano. El almacenamiento natural de frijol durante un ano corresponde al envejecimiento acelerado de 45 dias a 40° C y 76% humedad relativa.

Potential Nitrogen Source from Field Bean for Rainfed Mediterranean Cropping Systems

Field bean (Vicia faba L. var. minor Beck) is cultivated in the Mediterranean basin in rotation with winter cereals for dry grain production for animal feed, green forage, hay, silage, or green manure. This study aimed to (i) quantify the field bean fixed N during 2 yr at two Italian locations under rainfed conditions, (ii) quantify the proportion of N and fixed N allocated by field bean to grain, straw, and recoverable roots, and (iii) estimate the potential contribution of field bean to the cropping system N balance. The mean N percentage derived from N2 fixation of field bean grain and straw was 76%, corresponding to 114 kg ha–1 of fixed N in the aboveground biomass. On average, field bean fixed 42, 12, and 9 kg N Mg–1 dry matter in grains, straw, and roots, respectively. Recoverable roots contributed &lt;5% of the total plant fixed N, but estimates did not take into account rhizodeposition and fine root turnover. The net N balance was positive for green manure (117 kg N ha–1) and grain field bean without straw removal (31 kg N ha–1) but negative (–31 kg N ha–1) when straw was removed. The N gain vs. a non‐fixing species was 79, 62, and 117 kg ha–1 yr–1 for field bean used as grain without straw removal, grain with straw removal, and green manure, respectively. Our study indicated that field bean can play a significant role as a N source in rainfed cereal‐based cropping systems.

Efecto de la cantidad de rastrojo de arroz sobre las malezas y el frijol.

The assay was conductedbetween June 2000 and January 2001 at the Fabio BaudritExperiment Station of the University of Costa Rica, locatedin the San Jose district, in Alajuela, Costa Rica. The objectiveof the trial was to assess the influence of 0; 1.85; 3.70; 5.60;7.40 and 11 metric tons/ha (mt/ha) of dry matter of ricestubble (Var. CR-5272) as dead mulch on the ground surface,on the weeds and on the yield of the Huasteco bean variety,planted with least tilling. It was found that the rice stubble, inamounts over 3.7 mt/ha on the ground, drastically diminishedthe number of weeds, due mainly to the reduction of thetemperature fluctuations and the percentage ofphotosynthetic active and total light that reached the soilsurface. Besides, it improved the moisture holding capacityof the soil. The favorable effects of these factors werereflected in a greater production of bean grains.

Adubação nitrogenada em feijoeiro em sucessão a cultivo solteiro e consorciado de milho e Urochloa ruziziensis

A expansão do sistema plantio direto, no Brasil, está diversificando, cada vez mais, as formas como os métodos de produção são implantados e manejados. O presente estudo objetivou avaliar a influência de culturas antecessoras como o milho e Urochloa ruziziensis, bem como o consórcio entre estas, na presença e ausência de inoculação de sementes com Azospirillum brasilense, e o fornecimento de nitrogênio em cobertura sobre o desenvolvimento do feijoeiro e de seus componentes de produção e produtividade de grãos. O trabalho foi desenvolvido em Selvíria (MS), na safra 2011/2012. O delineamento experimental foi o de blocos ao acaso, com quatro repetições, em esquema fatorial 8x4, cujos tratamentos foram constituídos pela combinação de restos culturais (associações de milho, U. ruziziensis e A. brasilense) e doses de nitrogênio em cobertura no feijoeiro (0 kg ha-1, 30 kg ha-1, 60 kg ha-1 e 90 kg ha-1). As culturas antecessoras apresentaram efeitos na produtividade do feijoeiro, sendo o consórcio de milho e Urochloa, ambos inoculados, a melhor opção. A população inicial do feijoeiro não foi afetada pelas culturas antecessoras. A aplicação de nitrogênio em cobertura não interferiu na produtividade do feijoeiro, em cultivo irrigado de inverno, sob plantio direto.

Nondestructive Determination Of Beans Water Absorption Capacity Using CFA Images Analysis For Hard-To-Cook Evaluation

Hard to cook (HTC) phenomenon is developed by storing bean grains under the adverse conditions of high temperature (≥ 25 °C ) and high humidity (≥ 65 %). Bean grains that have undergone this HTC phenomenon are characterized by loss of color lightness, development of browning and darkening, and decrease of Water Absorption Capacity (WAC). The objective of this study was to develop a CFA (Color Filter Array) image processing system to measure Water Absorption Capacity (WAC) of bean grains with high precision in short time intervals (10 min). The relationships between the CFA image features, extracted from raw images captured by CCD (charge coupled device) camera, and the measured WAC were established. The calibration models using multiple linear regression (MLR) were developed to predict WAC. The MLR models for prediction samples resulted in correlation coefficient (R2) in the range of 0.811 to 0.947, standard error of prediction (SEP) in the range of 7.587 to 11.669, and Fisher variable value (F) in the range of 52.300 to 221.690. Results indicate that computer vision system (CVS) based on CFA image analysis technique can provide an accurate, reliable and nondestructive measurement method of WAC to evaluate the hard to cook defect in bean grains. DOI: http://dx.doi.org/10.11591/ijece.v3i2.2149

Nondestructive Determination Of Beans Water Absorption Capacity Using CFA Images Analysis For Hard-To-Cook Evaluation

Hard to cook (HTC) phenomenon is developed by storing bean grains under the adverse conditions of high temperature (≥ 25 °C ) and high humidity (≥ 65 %). Bean grains that have undergone this HTC phenomenon are characterized by loss of color lightness, development of browning and darkening, and decrease of Water Absorption Capacity (WAC). The objective of this study was to develop a CFA (Color Filter Array) image processing system to measure Water Absorption Capacity (WAC) of bean grains with high precision in short time intervals (10 min). The relationships between the CFA image features, extracted from raw images captured by CCD (charge coupled device) camera, and the measured WAC were established. The calibration models using multiple linear regression (MLR) were developed to predict WAC. The MLR models for prediction samples resulted in correlation coefficient (R2) in the range of 0.811 to 0.947, standard error of prediction (SEP) in the range of 7.587 to 11.669, and Fisher variable value (F) in the range of 52.300 to 221.690. Results indicate that computer vision system (CVS) based on CFA image analysis technique can provide an accurate, reliable and nondestructive measurement method of WAC to evaluate the hard to cook defect in bean grains. DOI: http://dx.doi.org/10.11591/ijece.v3i2.2149

Effects of seed inoculation by Rhizobium strains on yield and yield components in common bean cultivars (Phaseolus vulgaris L.)

To study the effect of Rhizobium inoculation treatments (inoculation with strains number 133, 116 and their integrated application) and chemical nitrogen fertilizer application (based on soil analysis in form of Urea) on certain agronomic traits of three common bean cultivars (viz. Bahman, Darkhshan and Sayyad) a field experiment was conducted at Agricultural Research Farm of College of Agriculture, University of Tehran (Karaj, Iran) during 2010 and 2011 growing seasons. The treatments arranged as factorial based on a randomized complete block design with three replications. The characteristics such as seed yield, pods number per plant, 100 seed weight, harvest index and biological yield were measured. Inoculated bean cultivars by rhizobium strain 116 produced the highest bean grain yield (5791 kg/ha). Bahman cv. inoculated by rhizobium strains 133+116 produced the highest number of pods per plant (55.97 pods/plant). Sayyad cultivar inoculated by rhizobium strain 116 produced the highest seed yield. Under the environmental conditions of this experiment, application of rhizobium strains proved to have the capability to replace the chemical nitrogen fertilizer in bean production.

The effect of extrusion and drying on roller techniques concerning the rheological characteristics of rice-, corn-, sweet potato-, bean- and cassava root- and leaf- based composite flour

Promoting food security in Latin-America and the Caribbean is directly related to agricultural products. The region faces a food crisis which has reduced large population groups' access to food. This work contributes to the study of obtaining precooked composite flour made from biofortified crops using protein, vitamin A and/or minerals. This study evaluated the effect of precooked flour's composition and precooking on its solubility in water, water absorption capacity, consistency and viscosity; such flour was obtained by extrusion and drying on rollers. The composite flours were obtained from cassava roots, sweet potato tubers, corn, rice and bean grains and cassava leaves. Four composite flours were formulated taking four- to six-year-old children's daily nutrient requirements (protein, iron, zinc and beta-carotenes) as a basis. The extruder was operated at 90oC, 300 rpm screw rotation speed, 17.64 g/min feed flow, with 30% moisture mixture. The dryer rollers were operated at 4 rpm roller rotation speed, 90oC surface temperature and 1 mm separation between rollers. It was determined that flour dried on rollers led to more complete cooking and modified starch granule structure than precooking by extrusion, thereby producing flour having greater solubility in water, less water absorption, higher consistency and smaller viscosity, comparable to that of pattern flour.

Correlação entre a produtividade do feijoeiro no sistema de produção orgânica e atributos do solo

Objetivou-se, com este trabalho, identificar um conjunto de atributos do solo, físicos (AF), químicos (AQ) e biológicos (AB) correlacionados com a produtividade do feijoeiro, visando estabelecer as condições de solo mais adequadas ao cultivo desta leguminosa no sistema de produção orgânica. Foram utilizados, conjuntamente, dados de dois experimentos instalados em novembro de 2003 com a cultivar Pérola, um em semeadura direta e outro em preparo convencional do solo, em Santo Antônio de Goiás, GO, em Latossolo Vermelho distrófico, no delineamento de blocos ao acaso, com quatro repetições. Os tratamentos consistiram das plantas de cobertura crotalária, guandu, mucuna-preta, sorgo vassoura e pousio. Foram realizadas amostragens de solo na camada de 0,00-0,10 m, em 2007, para determinação dos AF, AQ e AB. A produtividade apresentou correlação linear positiva com a porcentagem de agregados com diâmetro maior que 2 mm (AGR), diâmetro médio ponderado dos agregados, carbono da biomassa microbiana (CBM) e quociente microbiano, e negativa com o quociente metabólico, respiração basal e teor de cobre disponível. Pela análise de regressão linear múltipla conclui-se que os atributos do solo que melhor explicaram, de maneira conjunta, a produtividade, foram AGR, CBM e teor de matéria orgânica.

Nitrogen topdressing on common bean cropped in winter-spring in three cropping systems.

The aim of this study was to evaluate the nitrogen topdressing influence in common bean irrigated (winter-spring), in the first year of no tillage implementation. The experimental design was split-plot with three replications in randomized blocks. The plots were formed by three types of ground cover, corn-grain, corn-grain intercropped with Brachiaria ruziziensis and only B. ruziziensis . The subplots were formed by five doses of nitrogen topdressing (0, 40, 80, 120 and 160 kg ha-1), using urea as nitrogen source. It was determined the dry mass of residue present as ground cover, the full flowering time, the leaf nitrogen content, the 100 grains mass, the grain yield, the processing income, the chemical soil properties and economic analysis of common bean grain yield. It was found the common bean grain productivity in succession to corn-grain was positively influenced by nitrogen fertilization, showing it is economically viable only when given 160 kg ha-1 of nitrogen and the intercropping corn-grain and B. ruziziensis use is the best option when the common bean is sown in succession.

Adubação nitrogenada de cobertura no feijoeiro de invernoprimavera em três sistemas de cultivo

The aim of this study was to evaluate the nitrogen topdressing influence in common bean irrigated (winter-spring), in the first year of no tillage implementation. The experimental design was split-plot with three replications in randomized blocks. The plots were formed by three types of ground cover, corn-grain, corn-grain intercropped with Brachiaria ruziziensis and only B. ruziziensis . The subplots were formed by five doses of nitrogen topdressing (0, 40, 80, 120 and 160 kg ha-1), using urea as nitrogen source. It was determined the dry mass of residue present as ground cover, the full flowering time, the leaf nitrogen content, the 100 grains mass, the grain yield, the processing income, the chemical soil properties and economic analysis of common bean grain yield. It was found the common bean grain productivity in succession to corn-grain was positively influenced by nitrogen fertilization, showing it is economically viable only when given 160 kg ha-1 of nitrogen and the intercropping corn-grain and B. ruziziensis use is the best option when the common bean is sown in succession.

An approach to the decomposition of interaction in a factorial experiment with five factors

Factorial experiments are widely employed in agricultural research. In these experiments, inferences related to the interaction between factors are fundamental. However, many researchers are still unable to analyze this type of experiment, and others do not consider the effect of interaction. This study aims to exemplify a scheme for unfolding the degrees of freedom and to demonstrate the relevance of this rearrangement when the interaction is significant. For these purposes, the response variable time of cooking bean grains was measured in minutes using a completely casualized experimental design, with two replications, arranged in a 2 x 2 x 3 x 2 x 2 factorial scheme (fivefold classification). The following factors were evaluated: bean genotypes (2 levels), salt type (2 levels), salt dose (3 levels), hydration time (2 levels) and storage time (2 levels). The results highlight the importance of unfolding the degrees of freedom of the interaction every time it is significant because the possibility of evaluating the interaction between factors leads to conclusions related to the dependence between the factors. These results are more coherent with biological systems, and the example shown provides a solid basis for minimizing errors in factorial experiments.

Bioactive Compounds in Velvet Bean Seeds: Effect of Certain Indigenous Processing Methods

Effect of different indigenous processing methods on the levels of certain bioactive compounds in the seed materials of velvet bean (Mucuna pruriens L. DC), a promising wild type legume collected from different agro-ecological locations of the world, was investigated. Ten different accessions of velvet bean seeds were found to contain appreciable levels of certain bioactive compounds, such as total free phenolics (5.24–8.65 g/100 g DM), tannins (1.77–3.49 g/100 g DM), L-Dopa (4.30–6.23 g/100 g DM), and phytic acid (1.17–2.37 g/100 g DM). In general, velvet bean accession with black coloured seed coat (collected from Zimbabwe, Mexico, and Guinea) registered high levels of total free phenolics and tannins, whereas the maximum level of L-Dopa was detected in Guatemala accession. Furthermore, among the different indigenous processing methods employed in the present study, sprouting and oil-frying can be considered as mild and suitable treatment for the consumption of velvet bean grains as a natural source of health promoting bioactive compounds.

Petrology of the Eureka Quartzite (Middle and Late Ordovician), Utah and Nevada, U.S.A.

The Eureka Quartzite is a sheet-like quartzarenite up to 200-m thick that was deposited on the eastern shelf of the Cordilleran miogeocline from Canada to California. It is the only sandstone lithosome from the Middle Cambrian through Devonian succession in the Great Basin and is remarkable in its purity of detrital and authigenic quartz, scarcity of bedding, and heterogeneity of both grain packing and quartz cement abundance. Sand sources ranged from the Peace River Arch in Canada to the Transcontinental Arch in mid-continental North America. The Eureka represents a third-order regressive–transgressive stratigraphic sequence, although whether the regression formed in response to eustasy or epirogenic uplift of western North America is unresolved. The near absence of detrital clay, body fossils, and subaerial features in addition to the presence of herringbone cross-beds indicate that the Eureka was deposited in intertidal and shallow subtidal environments except for minor eolian deposits. Bioturbation destroyed most primary stratification, although discrete burrows are rare. Textural features of quartz (superb roundness, bean grain shape, crescentic impact scars) indicate a prolonged episode of eolian abrasion prior to marine deposition. Regionally the detrital composition is 99.5 percent detrital monocrystalline quartz, 0.5 percent K-feldspar and carbonate allochems, and a trace of heavy minerals. From 2 percent to 4 percent feldspar and carbonate allochems that were initially present have been replaced by quartz during burial. The chief authigenic phases are quartz overgrowths with minor calcite (now dolomite) and illite. Spheroidal and amoeboid calcite-cemented concretions up to 3 cm in diameter formed at shallow burial depths, but all carbonate in the concretions has been leached in outcrop. The heterogeneity of grain compaction and amount of quartz cement resulted in beds that range from semifriable to sedimentary quartzites in the same outcrop. Compaction by the combination of grain rearrangement, pressure dissolution, and grain fracturing generated anomalously low intergranular volumes that average 14 percent in Nevada and 21 percent in Utah. The normal evolution of microquartz overgrowths ( 10 μm) during cementation was retarded; consequently, microquartz and mesoquartz cement (80 percent) dominate over macroquartz (20 percent), and they are the only cements in the least-cemented beds and laminations. Illite co-precipitated with microquartz and impeded quartz cementation by coating quartz crystal faces. Despite reaching temperatures >135° C for ∼100 million years, much of the Eureka, especially in Utah, remains incompletely cemented and retains porosity of ∼2 percent. The chief cause of cement heterogeneity appears to be authigenic illite abundance. Pressure dissolution of quartz at shale beds and clay drapes that formed stylolites was the most likely major source of silica for quartz cement. Invasion by hydrocarbons and hydrogen sulfide (H2S) resulted in the reduction of iron in hematite grain coats on quartz grains, a remnant of their eolian dune formation, the bleaching of beds, and the generation of pyrite (now hematite). The abundance of iron that now resides in pyrite/hematite suggests that red beds were once widespread. Outcrop and near-outcrop processes generated Liesegang bands of iron oxide, desert varnish, “pockmarks” where carbonate cement in centimeter-scale concretions dissolved, hematite pseudomorphs of pyrite, and minor opal cement.