Tuesday, 16 April 2013

What is the sand and it`s characteristics ?

What is the sand and it`s  characteristics ?

Sand random accumulation of small pieces of rock, with dimensions seeds ranged between 0.063 and 2 mm on a scale Wentworth. Sand divided by its inception, into three main groups:

Sand continental erogenous sands: produces from previous weathering of rocks and fragmented configuration where the bulk animated cajoling and transferred to the sedimentation basins.

Carbonate sand: a marine origin and author of Krboonatih particles formed within the sedimentation basin (Sriat, fossils structures, gestures Krboonati) which is not in ruins to Michcla from breaking rocks previous configuration.

Detrital sand firearms pyroclastic sands: produced from volcanic eruptions, which is rich in volcanic debris in the form of real detritus bullet or continental if brought out of the land of ancient volcanic.

The most crucial of these sands, in terms of the diversity and proliferation, continental sand, and operates approximately 30% of the sedimentary cover in the earth's crust and are deposited at different rates, in all depositional environments, so the next study will focus on them.

General characteristics

Fall quartz sand within sand continental group and constitute the bulk of them. And characterized fabric texture and structure structure different sets general characteristics, namely in terms of the strength of two types: sand; It rocks disjointed uncorrelated, consists of beads clastic not combined with material carnivorous, and sandstones; It rocks interdependent and consists of beads clastic collected material for carnivorous.

 Metallic composition and chemical: quartz sand consists mainly of metal quartz (quartz), followed in importance metals sheets (feldspar), then metals mica Algdharyh, in addition to other miscellaneous metals incidental. The proportions of these components vary from sand to another depending on several factors, most important rocks mothers. Thus characterized by sand and quartz sandstone of chemically control silica SiO2 and alumina Al2O3 and iron oxides Fe2O3.FeO.

Colors: characterized by sand and quartz sandstones generally light colors white, and are rarely grim result presence of metal Amonettit or organic materials, and the structure or red when an iron mortar. The sandstones Elsafahih are pink or red, while colored sandstone Algluckonettih colors green variety.

Grain characteristics: characterized by quartz sand with a grain of properties, vary according to the nature of the source rocks, and factors physical or chemical weathering, and transport Alriha or water, continental or marine sedimentation.

- Measurement berries: quartz sand is located, according to international classifications applicable, within Aleranat family crinite, as dimensions of the quartz grains vary between 0.63 and 2 mm. And divide the sand and quartz sandstones, depending on the dimensions, into five groups grain (Figure 1). And loving dimension has been set for the Sand Molder using a sieve placed over each other, scalable openings of 2 mm and below, or through the study of microscopic slides for cohesive sandy rocks.

- Forms of pills: take quartz beads different forms, is determined by the degree of sphericity and beads balled Tdorha roundness, where cross-balling for approaching the pill degree of spherical shape depending on the ratio between the three main axes of the bead. There spherical and cylindrical beads and paper and blade and Gudaibiya, but Altdor thus expressed the curvature of the corners of the pill. According scale Altdor adopted globally beads are divided into very Mzoah beads, Mzoah, under Mzoah, under round, round, very round 

Quartz grains also feature smooth surfaces or rough unmarked different lines and scratches and pits and terrain. These surfaces may be opaque or opaque luster shiny brilliant luster. And reflect the detailed study of the surface texture of the beads using a scanning electron microscope of this berry and its history.

- Classification loving sorting: It means the control of one measure of my love. Show gatherings sandy different degrees of classification loving as can be poor, medium or good rating (Figure 3), and identifies these factors overlap transport and deposition. General and the sand is formed in the troubled areas good corrosion and loving balling and classification, while the sand is the worst in terms of river wear and classification as a result of different speeds of the water stream. Worse sand river sand Saliyah, then come sands Heels hillsides. The deep-sea sand degree of erosion and the balled عاليين and degree rated medium.

Geographical distribution of sand and quartz sandstones

Formed sand and sandstone in different circumstances and by very different factors. And deposited in the depositional environments of all: continental, marine and mixed specifications reflect the characteristics of these environments.

In continental environments spread quartz sand widely in the form of deposits desert, river and lake ice.

The sediment the flat plains of the desert sands area of ​​up to 7,500 square kilometers (Selima in the Libyan desert sand) is composed of a few feet thick caps resting on rock the cradle, or in the form of deposits undulating (neem marks) resembles its appearance whales. But the most important forms of Todatha are sand dunes and desert dunes beach when the banks aquariums, which tees asymmetrical and with peaks sharp forms crescent (Brkhanat) or Sevah or asterisk or straight, are deposited sand quartz where the form of intersecting layers cross bedding ranged thickness between a few meters and tens of meters, and up to 300 m, as is the case in Iran.

The sediment lacustris are limited deployment and minimal thickness, and structure of marine sandstones, and usually contains impurities Clay and wrecks Msthathih.

The river sediment corrosion and balling and classification, oblique stratification, and are deposited in the form of belts towards the stream and river valleys or when cornering river.

And glacial sediment formed as a result of erosion depositions Almourih obsolete water melting glaciers, and is characterized by good Bastafa love and wear-rate, medium-and apply cross Sealy or rivers.

In mixed environments (beach) are quartz sand in the form of bars or linear ranges blankets extended parallel to the shore line at distances up to 40 km long and 4 km wide, while not exceeding 20 m thick, and you know sand beaches or 'beaches'. Also located near the beaches of the sediment problem ductal channels and marine barriers barriers length up to several hundred meters, and a width of up to several tens of meters, and at an altitude of more than ten meters. There are also the form interfaces lenses within sediments very soft Algdharyh.

In marine environments sand Vttoda in areas facets marine platforms in the form of barriers barres or submerged underwater dunes forms elliptical intermittent. While there are in the deeper areas of the sea in the form of large deposits and homogeneous cover dozens or hundreds of square kilometers represented deposits turbidity currents and deep-sea sand deep see fan deposited in layers with grain scalable characteristics.

Naming and classification of quartz sand

Quartz sand and are classified according to several foundations and in different ways. And summed up most of quartz sand in the categories used equilateral triangle approach, which uses components main sand: Quartz - sheets - clay or rocky contents (Figure 4). This is based classification use a maturity maturity chemist and physicist, where he describes maturity chemical degree fastness metals towards factors weathering and transport, while describing maturity physicist histological changes undergone by sand from the weathering until sedimentation, especially the degree of sorting loving and content of sand from sediment minute ( Ground matrix). And the general outcome of the chemical and physical maturity increases in the direction of the top of the triangle representing the fixed or quartz grains (Figure 5). Applying this approach can be classified quartz sand and stones into two basic types: Aleranat and Allowaki.
Use system equilateral triangle in clarifying how to infer the maturation of sand
Through its components.
Be physically mature sand based on the proportion of its contents from terrestrial sediments, and mature chemically
Based on the contents of the metals is fixed.
Division of sand and quartz sand based on the use of clay indication of the maturation of tissue and the sheets as a parameter for maturation of chemical

Containing stones Aleranat less than 15% of terrestrial sediments (clays), while containing stones Allowaki between 15-75% of this sludge. Thus can be divided customary quartz sand into three main groups based on the degree of maturity chemist and physicist, namely:

- Quartzite stones: and includes both sand pure Alkuartza and sand Alkuartza initial orthoquartizite + protoquartizite rich Balmarw or rigid quartz or disjointed, a mature tissue and chemically referred to Quartz Beranat, and formed in shallow marine environments.

- Alerkoz stones: It is made up of quartz and sheets, and mature physically and chemically immature and are found in fluvial facies neighboring layers of granite and marine basins fixed or disruptive.

Allowaki stones: and includes both Allowaki gray greywacke and quartz Oaqui quartzwacke.

Petrophysical characteristics of the sand and quartz sandstones

Enjoy pure quartz sand porosity initial porosity between high grain (Figure 6) ranged between 10% and 35%, and up to 45% in the loose sand. Quartz sand is classified depending on the porosity of the poor and weak, medium and good and high porosity. And take the spaces between the grains sizes and different forms depending on the formal qualities of the surrounding beads. As these initial porosity closely associated with fabric and style packaging packing berries, where landing porosity value of 48% in Almkobei system, which is the most fragmented, to 26% in rhomboid packaging system, which is the most cohesion. And affect the merger (Clinch) during and after deposition in the original porosity. So the porous clay be very high and during the time of deposition (85%), and decreases after the burial of this sludge because of the merger.
Produces porosity in quartz sand private permeability permeability that reflect the ability of the fluid to move into the middle and through porous channels and corridors with sinuous shapes and different sections. Sands are classified according to the values ​​permeability to weak, medium and good and high permeability. The suit permeability is proportional to the size of the grains vary the medium-sized box of pills and inversely proportional to the logarithm of coefficient rating loving. Permeability is also affected grains and packaged forms.

The economic importance of sand and quartz sandstones

Important Alkhoznip: lend porosity and permeability Graham Walter on the sand and quartz sandstones good Khoznah properties make it an important oil tanks allow the accumulation of hydrocarbons and positioned to contain a huge stockpile of crude oil and natural gas. If what Asttnint fields massive carbonate in the world, the sand and sandstones contain two-thirds of the world's oil reserves and natural gas. Not only is this important sand to contain a high stock of oil, but it also brings to the ease of detection compared with carbonate formations. The compounds of these silicate rocks are not affected by incidents physical and chemical transformation that lead to loss of porosity in carbonate rocks.

Sand reservoirs are classified according to the depositional environments in which they occur according to different groups, each with its own characteristics depositional and engineering, petrophysical and petroleum. These gatherings are important oil traps, especially in the fields of the North Sea and the Arab region.

In case it does not contain hydrocarbons reservoirs, or depletion of their content, it can be invested in underground storage operations for natural gas newly popular in the world. Is also a sand and sandstone important source of groundwater.

Industrial uses: quartz sand fall within the list of useful raw materials used in many industries. They constitute the main raw material used in the manufacture of glass. As intervention in different proportions in the manufacture of cement, ceramics and building materials, in addition to its use in polishing and grinding and water purification. Quartz sand are also used asphalt to get asphalt for paving roads

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