Heavy minerals full paper

Heavy minerals conference-2013

CONCENTRATION AND DISTRIBUTION PATTERN OF HEAVY MINERALS IN BEACH SANDS, INTERRELATIONSHIP OF TEXTURAL AND HEAVY MINERAL ABUNDANCE OF THE NERELLA VALASA TO

JALARA PETA VISAKHAPATNAM. ANDHRA PRADESH, INDIA.

Vadde Ramesh1, K.Lokeswara Rao2, V.V.Nageswara Rao3 and P.Bhanu Murthy3

Contact Author:

Full name: Vadde Ramesh

Designation: Research scholar

Organisation Name: Andhra University

Address: Department of Geology, AU College of Science and technology, Andhra University, Visakhaptnam-530003,AP,India.

Mobile:+91- 8500753406

Email: [email protected]

CONCENTRATION AND DISTRIBUTION PATTERN OF HEAVY MINERALS IN BEACH SANDS, INTERRELATIONSHIP OF TEXTURAL AND HEAVY MINERAL ABUNDANCE OF THE NERELLA VALASA TO

JALARA PETA VISAKHAPATNAM. ANDHRA PRADESH, INDIA.

Vadde Ramesh1, K.Lokeswara Rao2, V.V.Nageswara Rao3 and P.Bhanu Murthy3

1. Research scholarDepartment of Geology Andhra [email protected]

2. Research scholarDepartment of Geology Andhra [email protected]

3. ProfessorDepartment of Geology Andhra [email protected]

4. ProfessorDepartment of Geology Andhra UniversityVisakhapatnam-530003.

Extended AbstractVisakhapatnam city is situated on the east coast of Andhra Pradesh, India. The area of

investigation lies in between Narella valasa to Rushikonda and Latitudes 170461 to 170 541, Longitudes 830211 to 830 271 .at five stations from Nerella Valasa to Jalara peta 27 samples were collected at a distance of nearly 1 kilometer representing dune, backshore and fore shore environments respectively. At each station sediment sample weighing 250 grams were collected in each environment. To study the placer minerals in terms of their occurrence, distribution chemical composition, texture, provenances and to understand the transportation trends of sediments. A very few study were undertaken in micro environments of Indian beaches related it heavy mineral variation in respect of density and size. The weight percentage of heavy minerals ranges from 15 to 50% in the study area some sediment samples contain more than 50% of minerals. Based on study data the weight percentage of heavy minerals is very high in fraction and it decreases as the grain size of the particles of the particles increase, it can be concluded that heavy mineral fraction has good association with fine grained particles.

In this studies among the opaque mineral ilmenite and Magnetite are common. The concentration of opaque minerals is very high in fine fraction than in the medium and coarse fractions. The percentage of heavies decreases as the grain size increases. Studies of silliminite in study area suggest that, they are largely derived from the Khondalite occurring in the Eastern Ghats. The provenance of garnets is related to khondalite suite (GARNET-SILLIMANITE-GRAPHITE GENISSES AND SCHISTS)of Eastern Ghats some dark brown garnets are noticed in the present study.the the weight percentage of the Zircon in Dune environment of Coarse fraction ranges from 1.2 to 9% the concentration of Zircon in the medium fraction is from 1.7 to 9.5%. Monazites are present only in few samples in minor portions. The weight percentage of Monazite in dune environment of coarse fraction ranges from 0.5 to 10%. The concentration of the monazite in medium fraction is from 0.8 to 10%. In fine fraction their range is from 0.2 to 0.5%. Epidote is also one of the minor constituent of heavy minerals. Epidote is derived from low grade metamorphic rocks Khondalites and Pyroxene Granulites.

All the microenvironment viz Dune, Back shore, Foreshore from Jalara Peta to endada coast has similar heavy minerals assemblage, the heavy mineral assemblages consist of dominantly Opaque, Silliminite, Garnet Zircon, Epidote, Monazite, and Trace of Rutile, with some other minerals like Pyroxene, Amphiboles, Biotite,etc. the total heavy minerals content various from 1.5 to 60%.

INTRODUCTION:Many investigators have worked on east coast beaches to discriminate various environments (Roy and Biswas (1975), Chandramohan et al., (1981), Kshirasagar and Nagamalleswara Rao (1989), Sahu et al., (1997), Joseph et al., (1997), Mohan andRajamanickam (1998), Nagamalleswara Rao (1998), Nagamalleswara Rao et al., (1998)

and others).Studies on grain size statistics, dynamic conditions and morphological conditionsof east coast beaches were carried out by Prudviraj and Vaidyanadhan (1978), Vaidyanadhan (1987), Sundar and Sarma (1992), Chauhan (1992,1995) and Ramanujamet al., (1996). Chemistry and Radiometry of placer minerals along East Coast beacheswere examined by Ramamohana Rao et al., (1983), Kshirasagar and NagamalleswaraRao (1989), Nagamalleswara Rao (1994) and Lakshmipati Raju and Srinivasa Rao(1996).Mallik (1981), Sastry et al., (1981), Mohan (1995), and Hanamgond and Chavadi(1998) studied the distribution pattern of heavy minerals and estimated their percentages.The occurrence and concentration of heavy minerals were studied by Mahadevan and Satapathi (1948), Sastry et al., (1987), Nagamalleswara Rao (1994), Sahu et al., (1997), Reddy and Prasad (1997), Nagamalleswara Rao (1998), Reddy et al., (1998), Reddy andPrasad (1998) and Acharya et al., (1998).From an analysis of the profile data available with the Visakhapatnam portmanagement, Sriramdas (1948) noticed the long-term morphometric changes alongVisakhapatnam beach. Short and long term beach cycles along the Visakhapatnambeaches were studied by Lafond and Prasada Rao (1954), Prasada Rao (1954,1956),Prasada Rao and Mahadevan (1958), Vijayan et al., (1960), Ramanadhan andVaradarajulu (1967), Anantharam (1969), Subba Rao and Madhusudana Rao (1970),Ramanadhan and Varadarajulu (1972), Sastry et al., (1979), Dhanalakshmi (1980) andVasudev (1982).

PHYSIOGRAPHY OF THE AREA OF INVESTIGATION:

GeomorphologyThe shape of the shoreline, artificial and natural barriers that intercept the waves,currents, sediment drift on the beach and relief of the sea bottom in the near shore area affect the waves approaching the shore. Straight beaches are the simplest types of shoreline. However, natural features like rocky promontories, growth of deltas and small spits and barrier beaches, modify the alignment of the shoreline, leading to highly complex shapes and sometimes they give rise to coastal landforms, such as lagoons, bays, etc. They culminate in destruction of coastal property or creation of new land areas. The coastal stretch from Nerellavalasa to Jalara peta is a special physiographic setting. The Kailasa hill at the starting of the study area rose to height of 510 meters above the mean sea level. From the Eastern promontory the hill rapidly rises to higher levels towards the west. The continuity of the hill is broken up abruptly by a wind gap near Venkojipalem. North of the Kailasa hill and near the coast, various small-detached hills arepresent near Gudlavanipalem.

GEOLOGY OF THE STUDY AREA:The prominent Geological formations of the area belong to Archean and Quaternary periods. The Archeans include mainly; Khondalites, Leptynites, Charnockite, Granites,Pegmatite and Quartz veins. Quaternary sediments include; Laterite and Surficial deposits.

GEOLOGICAL SETTINGS OF THE AREA OF INVESTIGATION

SYSTEM AGE STRATIGRAPHICQuaternary Recent Surfacial deposits, Piedimont fansColluviums and red sediments.Sub recent Laterite/Lateritic gravel

Archeans Precambrian Quartz veins,Pegmatites, GranitesCharnockite, LeptyniteKhondalites and Sand

Fig.1 Sample locations of the study area (Nerellavalasa to Jalara peta).

HEAVY MINERAL ASSEMBLAGE:The various heavy mineral species present in a sediment or rock constitute the heavy mineral assemblage. An important aspect of interpretation involves comparison of these assemblages. Rock units in a vertical succession containing different assemblages are called heavy mineral zones. In the case of lateral variations with in a Lithologic unit, the various assemblages are known as heavy mineral association. Several related associations characterize a sedimentary petrologic province (Blatt et al., 1980).The important factors which control the heavy mineral assemblages are as follows.1) Source rock composition and dispersal. 2) Temporal variations in the source area.3) Selective sorting during transport and deposition. 4) Selective removal after deposition.Although most heavy mineral assemblages contain a variety of mineral species they rarely constitute more than 1% of the total volume of the sediment particles. Some minerals like Zircon and Rutile this may be applicable as they form minor constituents in the source rock. Some other minor abundant species like Amphibole and Pyroxene are relatively unstable in the source area and may not adequately represent in the heavy mineral suite. The origin of many heavy mineral species is limited to rather specific rock types. Heavy mineral assemblages in marine deposits are strongly influenced by major rivers and adjacent land masses with variable lithologic units of drainage basins. In fluvial sequences heavy mineral associations, which are largely controlled by the distribution of different rock types in the source area can provide clues to establish paleo history. Minerals present in the younger beds but absent in the older ones are commonly less stable species. This situation generally involves deposition through several geological epochs.

METHOD OF STUDY

FIELD WORK AND SAMPLE LOCATION:

At five stations from Nerellavalasa to Jalara peta 27 samples were collected. In each station 3 samples were collected at a distance of nearly 1 Kilo Meter representing Dune, Back shore and fore shore environments respectively. The location of the samples in the study area was shown on the location map (fig.1). “At each station sediment sample weighing 250 grams were collected in each environment.”

PROCEDURE:From nine locations 27 representative samples were processed for heavy mineral studies. The procedure outlined by Carver (1971) was adopted for heavy mineral studies and is presented here. It is given in the following sessions. Initially the samples were wet sieved through + 230 ASTM sieve mesh (0.062mm). The +230 mesh fraction was treated with Hydrogen Peroxide (H2O2) (15%) to remove organic matter and also treated with 10% Dilute HCl in order to remove the shell material. Then part of it was divided by dry sieving into +60 (0.25mm, Medium sand), +60 to +120 (0.25 to 0.125mm, Fine sand) and +120 to +230(0.125 to 0.062mm, Very fine sand) ASTM mesh size fractions. The procedure is briefly described in the following paragraphs. Out of the 250gm of the sediment sample a representative of 100gm of sample is considered after coning and quartering procedure. In the next setup 100gram sample is soaked in distilled waster, to dissolve salts, in H2O2 to dissolve carbonate material and in HCl to dissolve Shelly material for 12 hours respectively. Later the sample is soaked in NH3 to disperse the grains for a period of 12hours.Afterwards the sample is washed with distilled water for two or three times. After this the sample is divided into two fractions (i.e. sand plus silt and clay) with the help of 230 mesh. The sample which remained in 230 mesh is considered as sand and it is collected in beakers and dried in a oven for a couple of hours. The dry sample is placed in the uppermost sieve in a set of stacked sieves. The stack of sieves

arranged in a systematic order so that the coarsest sieve is at the top with finer ones below is placed in a sieve shaking machine (the sieve numbers are 18, 25, 35, 40, 60, 80, 120, 170, 230, and -230 respectively) and after 15 minutes of shaking the sand that remained on each sieve and the base pan is removed and weighed. From these values weight percentage of each mineral is found. The weight percentage and average weight percentage of heavies in each sample are given in the Table: 1.

METHODS OF SEPARATION AND ANALYSIS:Heavy minerals are separated from the more abundant light minerals by Gravity separation in a high density liquid. Most commonly used heavy liquids are listed below:NAME FORMULA Sp. Gr. at 2O0 CBromoform CHBr3 2.89, (Tribron – Methane), Acetylene Tetra bromide C2H2Br4 2.96,(Tetrabrom – Ethane),Methylene Iodide CH2I2 3.32.The light mineral fraction (i.e. Quartz, Feldspar, Calcite, and most Lithic grains) can be easily separated from the heavy fraction by using Bromoform or Acetylene Tetra bromide. After the initial separation, Methylene iodide may be used to segregate the heavy minerals whose specific gravity is less than 3.3 from those whose specific gravity is greater than 3.3. In the present investigation Bromoform (Sp.Gr. = 2.89) was considered as the separation liquid to separate the heavy minerals from the lighter minerals.Magnetic fraction of heavy minerals was separated with a horse shoe magnet and their weight percentage is directly added to the total heavy mineral percentage. PROCEDURE TO SEPERATE HEAVY MINERALS DISTRIBUTION OF HEAVY MINERALSIn India, beach sand mineral exploration and exploitation started in the beginning of the 20th century after the accidental discovery of monazite from the beach sands of Travinecore State by a German scientist, Schombery. Several scientists have made their attempts to study the placer minerals in terms of their occurrence, distribution, chemical composition, texture, provenance, and to understand the transportation trends of sediments. A very few studies were undertaken in microenvironments of Indian beaches related to heavy mineral variation in respect of density and size etc. This chapter, were deal with the heavy mineral characteristics and their distribution in the microenvironments of beach include Dune, Back shore and fore shore. The influence of hydraulic fractionation, by shape and density on total variability of heavy mineral concentration. Influence of accretional and erosional trends of the beaches to heavy mineral concentration was also being discussed. The weight percentage of heavy minerals ranges from 15 to 50% in the study area. Some sediment samples contain more than 50% of heavy minerals. In the Dune environment, the (+ 60) fraction weight percentage of heavy minerals ranges from 0.9 to 6.5%, in medium (+120) fraction the range is from 3 to 43% and in fine (+230) fraction range is from 3 to 26%. The weight percentage of the Heavy Minerals is given in the Table1.1. In the Back shore environment, the (+ 60) fraction weight percentage of heavy minerals ranges from 1.5 to 3%, in medium (+120) fraction the range is from 2 to 7.5% and in fine (+230) fraction range is from 2 to 63%. The weight percentage of the Heavy Minerals is given in the Table1.2.In the Fore shore environment, the (+ 60) fraction weight percentage of heavy minerals ranges from 1.1 to 1.8%, in medium (+120) fraction the range is from 0.6 to 3.5% and in fine (+230) fraction range is from 2.5 to 16%. The weight percentage of the HeavyMinerals is given in the Table1.3. Based on the data the weight percentage of heavy minerals is very high in fine fraction and it decreases as the grain size of the particles increase. It can be concluded that heavy mineral fraction has good association with fine grained particles.

OPAQUES:Among the Opaque minerals Illmenite and Magnetite are common. The Opaque are sub angular to sub rounded in shape and are black in colour and exhibiting Framboidal texture.The weight percentage of the opaque minerals in Dune environment of coarse (+60) fraction ranges from 15 to 44%. Opaques concentration in the medium fraction (+120) sediments varies from 15to 46%. In fine fraction (+230) the weight percentage of Opaques ranges from 84.29 to 91%. In Back shore environment

of coarse (+60) fraction ranges from 15 to 36%. Opaques concentration in the medium fraction (+120) sediments varies from 21 to 63%. In fine fraction (+230) the weight percentage of Opaques ranges from 77 to 90%. In Fore shore environment of coarse (+60) fraction ranges from 30 to 56%. Opaques concentration in the medium fraction (+120) sediments varies from 30 to 56%. In fine fraction (+230) the weight percentage of Opaques ranges from 0.4 to 1.2%. The concentration of Opaque minerals is very high in fine fraction than in the medium and coarse fractions. The percentage of heavies decreases as the grain size increases.

SILLIMANITE:Sillimanite is colourless splender, prismatic grains with perfect cleavage. They are Non – pleochroic and show straight extinction. Sillimanite shows angular edges some times rounded at termination. In some of the mineral Opaques, unidentified inclusions are noticed and few of the minerals showing step like structure and pits, these are showing moderate relief, all these are related to the effects of mechanical impact and chemical action (Mallik, 1986). Sillimanite is the second dominant mineral in non – opaque heavy minerals in the present study. In the Dune environment, the weight percentage of the Sillimanite in the coarse fraction (+60) is varying from 9 to 36%. In the medium fraction (+120) Sillimanites range isfrom 11 to 44%. In fine fraction (+230), the percentage of Sillimanite ranges from 0.4 to 7%.Sillimanite abundance in fine fraction is lower than the medium and coarse fractions. In the Back shore environment, the weight percentage of the Sillimanite in the coarse fraction (+60) is varying from 10 to 51%. In the medium fraction (+120) Sillimanites range is from 17 to 41% and In fine fraction (+230), the percentage of Sillimanite ranges from 2.7 to 17%. Sillimanite abundance in fine fraction is lower than the medium and coarse fractions. In the Fore shore environment, the weight percentage of the Sillimanite in the coarsefraction (+60) is varying from11 to 41%. In the medium fraction (+120) Sillimanites range is from 17 to 41% and In fine fraction (+230), the percentage of Sillimanite ranges from 5 to16%. Sillimanite abundance in fine fraction is lower than the medium and coarse fractions. Study of characteristics of Sillimanite in study area suggests that, they are largely derived from the Khondalites occurring in the Eastern Ghats. The prismatic character of the minerals (Sillimanite) also suggests their derivation from Khondalitic rocks (Murthy, 1966).

GARNETS:Garnets are colourless, pale pink and few are pink in colour. They exhibit angular to sub – angular and rounded forms with conchoidal fractures, some grains have etching spots breaked edges, pits and inclusions of Opaques. Garnets are distinguished from other heavy minerals by their Isotropic nature, high relief and often Iron oxides are associated. In Dune environment , the coarse fraction (+60) Garnets ranges from 25 to 47%. In medium fraction (+120), Garnet ranges from 13 to 63%. In fine fraction (+230) Garnets ranges from 0.4 to 6.5%. In Back shore environment, the coarse fraction (+60) Garnets ranges from 21 to 50%. In medium fraction (+120), Garnet ranges from 2 to 50%. In fine fraction (+230) Garnets ranges from 1.3 to 6%. In Fore shore environment, the coarse fraction (+60) Garnets ranges from 12 to 39%. In medium fraction (+120), Garnet ranges from 8 to 44%. In fine fraction (+230) Garnets ranges from 2.5 to 7%. Garnets are of two types, colourless and pale pink. The provenance of Garnets isrelated to Khondalite suite (Garnet – Sillimanite- Graphite Genisses and Schists) of Eastern Ghats, occasional dark pink Garnets are derived from Charnockite (Viswanathan 1965;Mallik 1968). Some dark brown Garnets are noticed in the present study.

ZIRCONS:Generally Zircons are Eu-hedral character but in the present study rounded to sub rounded Zircons are rounded which are, yellow and brown in colour with straight extinction. In some of the grains, inclusions of Opaques were present. Some varieties of Zircons show colorless nature. The weight percentage of the Zircons in Dune environment of coarse fraction ranges from 1.2 to 9%. The concentration of Zircon in the medium fraction is from 1.7 to 9.5%. In fine fraction they range from 0.5 to 4.5%. In some samples

Zircons are completely absent. In some samples rounded Zircons are present which indicates that the sediments are formed from reworked sediments. In Back shore environment of coarse fraction ranges from 1.5 to 4.5%. The concentration of Zircon in the medium fraction is from 2 to 7%. In fine fractionthey range from 0.9 to 5%. In Fore shore environment of coarse fraction ranges from 1.2 to 2%. The concentration of Zircon in the medium fraction is from 1.2 to 2.1%. In fine fraction they range from 0.9 to 1.7%.

RUTILE:The Rutile grains are red, thick red to brownish in colour with prismatic shape. But most of the Rutile grains in the present study are rounded nature and some samples exhibits kidney form. Some Rutiles in the study area are in anhedral form which indicates that the sediments are immature.The weight percentage of the Rutile, in Dune environment of coarse fraction is from1.5 to 8%. The concentration of Rutile in medium fraction is from 0.5 to 3%. In fine fraction their range is from 0.2 to1.2%. Presence of rounded Rutile in some samples indicates that they are sourced from reworked sediments. In some places anhedral Rutiles are also present. They are probably derived from the adjoining acidic and Igneous and Metamorphic rocks. In Back shore environment of coarse fraction is from0.6 to 3%. The concentration of Rutile in medium fraction is from 0.5 to 8.5%. In fine fraction their range is from 0.5 to1.2%. In Fore shore environment of coarse fraction is from 0.5 to15%. The concentration of Rutile in medium fraction is from 0.5 to 13%. In fine fraction their range is from 0.3 to 1.3%.

MONAZITE:The Monazite grains are colour less to yellow and are characterized by rounded to sub rounded shape. They are present only in few samples in minor proportions. The weight percentage of Monazite in Dune environment of coarse fraction ranges from 0.5 to10%. The concentration of monazite in medium fraction is from 0.8 to 10%. In fine fraction their range is from 0.2 to 0.5%. Presence of Monazites indicates that they are derived from charnockites. In Back shore environment of coarse fraction ranges from 0.8 to 13%. The concentration of monazite in medium fraction is from 0.8 to 12%. In fine fraction their range is from 0.1 to 1.1%. In Fore shore environment of coarse fraction ranges from 0.8 to 11%. The concentration of monazite in medium fraction is from 0.8 to 11%. In fine fraction their range is from 0.1 to0.5%.

EPIDOTE:Epidote is also one of the minor constituent of heavy minerals. Most of the grains are in colourless and some are Yellow, Greenish in colour with sub rounded shape and they show Pleochroism. The charted distribution maps show the variation of Epidote in three fractions. Epidote is derived from low grade metamorphic rocks like Khondalites (Mallik, 1968).and Pyroxene Granulites.The weight percentage of the Epidote in Dune environment of coarse fraction ranges from 0.5 to 2.7%. The concentration of Epidote in medium fraction is ranges from 1.4 to 2.5%. In fine fraction their range is from 0.2 to 0.6. In Back shore environment of coarse fraction ranges from 1.1 to 3.2%. The concentration of Epidote in medium fraction is ranges from 1.6 to 2.2%. In fine fraction their range is from 0.2 to 1.4%. In Fore shore environment of coarse fraction ranges from 0.5 to 1.5%. The concentration of Epidote in medium fraction is ranges from 0.6 to 1.5%. In fine fraction their range is from 0.3 to 1.5%.

T H I N S E C T I O N SIN PLANE POLARIZED LIGHT UNDER CROSSED NICOLS

INDEX: ILM: Ilmenite; SIL: Sillimanite; RD ZIR: Rounded Zircon;RUT: Rutile.IN PLANE POLARIZED LIGHT UNDER CROSSED NICOLS

INDEX: ILM: Ilmenite; SIL: Sillimanite; GAR: Garnet; RUT: Rutile.

IN PLANE POLARIZED LIGHT UNDER CROSSED NICOLS

INDEX: ILM: Ilmenite; SIL: Sillimanite; GAR: Garnet; HPY: HyperstheneIN PLANE POLARIZED LIGHT UNDER CROSSED NICOLS

INDEX: ILM: Ilmenite; SIL: Sillimanite; GAR: Garnet; MZ: Monazite; RUT: Rutile; ZIR: Zircon.

R E S U L T SThe results within the experiment varied with each sediment sample. The mineral distinctions with in each sample helped categorize each sample with its on area. Each sample was carefully studied and heavy minerals were identified to make sure the results were as accurate as possible.For all the samples first the weight percentage of the heavies were arrived by the procedure described in the Methodology, the weight percentage of the all samples is given in the Tables: 1.1,1.2&1.3.Due to certain natural difficulties, the weight percentage of the heavies in some sample is not equal to 5 grams which is a prerequisite to the heavy mineral studies. Hence among all only a few sample, which shows maximum and minimum percentage of the heavies are taken for the heavy mineral analysis.Total average weight percentage of the each heavy mineral in Dune, Back shore and Fore shore environments is given in the Tables: 2.1, 2. 2 & 2.3.. Finally PHI-charts are drawn to the weight percentage of the each samples. They are shown in the following sections. Through insight into the data sets reveal that the heavies are associated with fine (+230) fractions (very fine sand) and only three minerals opaque, Sillimanite and Garnets are presents in more than 85%. And other minerals constitute only 15%. In a few slides, grains have lost their original optical properties because of their transportation leading to certain difficulties to establish their precise identification and need supportive studies such as XRD to name them properly.

All the microenvironments viz dune, back shore and fore shore from Jalara peta to endada coast has similar heavy mineral assemblage. The heavy mineral assemblages consist of dominantly opaques, Sillimanites, garnets, zircons, Epidote, monazites and traces of rutile, with some other minerals like pyroxenes, amphiboles, Biotite etc.Thetotalheavy mineral content varies from 1.5 to 60%.

TABLE 1.1 WEIGHT PERCENTAGES OF HEAVY MINERALSIN DUNE ENVIRONMENT

Sl.No. Location In + 60 fraction In + 120 fraction In + 230 fraction1 Nerellavalasa 8 10 10.62 Kotturu 17.36 37.54 903 Hamsavaram 5.78 39.2 3.24 Rushikonda 7.12 30.6 53.45 Endada 6.28 43 21.026 Appughar 14 54.6 2.67 Jalari endada 0.9 6.8 23.028 Jalaripeta 3.78 18.12 26.72

TABLE 1.2 WEIGHT PERCENTAGES OF HEAVY MINERALSIN BACK SHORE ENVIRONMENT

Sl.No. Location In + 60 fraction In + 120 fraction In + 230 fraction1 Nerellavalasa 11.88 10.8 23.362 Kotturu 1.4 1.52 1.523 Hamsavaram 3.58 3.34 23.364 Rushikonda 1.66 2.08 05 Endada 2.56 2.68 63.26 Appughar 2.96 7.18 1.747 Jalari endada 2.02 1.68 36.148 Jalaripeta 1.52 1.78 27.56

TABLE 1.3 WEIGHT PERCENTAGE OF HEAVY MINERALSIN FORE SHORE ENVIRONMENT

Sl.No. Location In + 60 fraction In + 120 fraction In + 230 fraction1 Nerellavalasa 7.04 32.28 262 Kotturu 2.14 1.9 8.93 Hamsavaram 4.22 0.3 04 Rushikonda 1.56 0.76 5.75 Endada 1.12 1.42 15.226 Appughar 1.66 3.48 2.287 Jalari endada 1.76 1.56 3.98 Jalaripeta 1.16 0.6 15.74

Table2.1 Weight Percentage of Heavy Minerals in 60+ FractionStation Environment Sillimanite Garnet Epidote Zircon Monazite Rutile opaque UnknownNerellavalasa Dune 35.48 32.98 0.45 5.1 9.31 0 15.08 1.6Kotturu Dune 25.65 45.43 0.68 1.76 0 5.54 18.69 2.25Hamsavaram Dune 9.63 46.91 1.06 1.2 0.5 8.35 30.44 1.9Rushikonda Dune 32.76 28.15 0.59 5.54 1.3 3.61 25.88 2.16Endada Dune 19.27 34.13 1.3 3.08 2.81 8 29.71 1.7Appughar Dune 8.13 35.99 2.1 2.7 3.56 1.4 43.83 2.3Jalari endada Dune 21.62 24.61 2.43 3.14 4.05 6.05 35.88 2.21

Jalaripeta Dune 23.95 33.93 2.6 9.18 2.1 1.7 24.17 2.37Nerellavalasa Back shore 34.17 32.67 1.45 3.93 3.59 0 22.85 1.34Kotturu Back shore 27.67 24.5 1.2 1.58 12.1 2.5 29.85 0.6Hamsavaram Back shore 10.6 49.25 1.24 7.62 6.95 0.6 22.04 1.7Rushikonda Back shore 39.64 28.35 1.3 4.38 0.8 2.81 21.22 1.5Endada Back shore 33.02 29.23 1.13 3.96 3.61 2.53 25.05 1.47Appughar Back shore 50.92 25.36 1.9 2.34 0.78 2.11 14.35 2.24Jalari endada Back shore 33.77 22.43 2.28 2.45 11.08 1.6 24.31 2.07Jalaripeta Back shore 31.42 20.87 3.2 3.94 1.8 1.43 35.17 2.17Sivajipalen Back shore 26.91 29.78 2.17 2.6 1.34 1.7 33.56 1.94Nerellavalasa Fore shore 28.79 27.31 0.62 0 2.7 8.1 30.78 1.7Kotturu Fore shore 21.73 37.84 0.57 1.4 2.3 0.5 34.98 0.68Hamsavaram Fore shore 11.66 25.8 0.57 1.3 1.5 1.7 55.67 1.8Rushikonda Fore shore 40.57 13.47 0.73 1.2 0.93 13.31 28.43 1.36Endada Fore shore 32.9 11.65 0.78 1.4 2.88 0.96 48.6 0.83Appughar Fore shore 16.49 32.86 0.97 1.35 10.82 0.76 35.8 0.94Jalari endada Fore shore 44.5 19.7 1.23 1.53 0.85 1.35 29.99 0.86Jalarapeta Fore shore 10.79 33.45 1.16 1.56 9.44 0.9 40.86 1.84

Table2.2 Weight Percentage of Heavy Minerals in 120+ FractionStation Environment Sillimanite Garnet Epidote Zircon Monazite Rutile opaque UnknownNerellavalasa Dune 11.22 20.18498 1.56 5.1 9.31 1.13 15.08 1.3Kotturu Dune 32.8 25.61865 1.67 1.76 1.25 1.6 18.69 1.46Hamsavaram Dune 18.27 62.21847 1.83 2.07 0.84 2.11 30.44 1.46Rushikonda Dune 27.03 13.76059 1.73 5.54 0.98 2.53 25.88 1.45Endada Dune 29.71 13.12 1.86 3.08 2.81 2.81 44.93 1.68Appughar Dune 43.83 22.19 1.94 2.14 3.56 1.56 22.81 1.97Jalari endada Dune 35.88 17.27 2.35 2.65 4.05 0.9 34.79 2.1Jalarapeta Dune 24.17 22.27 2.16 9.18 2.1 0.59 37.57 1.96Station Environment Sillimanite Garnet Epidote Zircon Monazite Rutile opaque UnknownNerellavalasa Back shore 32.48 32.67 1.45 3.93 3.59 0.48 22.85 1.13Kotturu Back shore 32.96 24.5 1.48 1.74 2.1 6.05 29.85 1.25Hamsavaram Back shore 40.57 49.25 1.6 7.62 6.95 0.76 22.04 1.27Rushikonda Back shore 17.65 28.35 1.32 4.38 0.86 8 21.22 1.23Endada Back shore 25.05 7.87 1.54 3.96 3.61 3.61 52.89 1.47Appughar Back shore 14.35 8.21 1.85 2.23 0.87 8.35 62.28 1.86Jalari endada Back shore 24.31 9.95 2.17 2.35 11.08 5.54 42.73 1.87Jalaripeta Back shore 35.17 5.09 2.06 2.14 2.36 0.62 50.99 1.57Sivajipalen Back shore 33.56 1.97 1.87 1.93 1.27 0.75 57.22 1.43Nerellavalasa Fore shore 5.44 27.31 1.2 1.45 2.7 8.1 30.78 0.8Kotturu Fore shore 8.81 43.29 0.9 1.26 0.97 1.23 34.98 0.83Hamsavaram Fore shore 6.28 25.8 0.86 1.23 0.83 1.2 55.67 0.76Rushikonda Fore shore 9.84 13.47 0.63 0.85 1.32 13.31 28.43 0.76Endada Fore shore 29.77 12.45 1.13 3.15 2.88 0.97 48.6 1.05Appughar Fore shore 33.15 15.6 1.23 1.5 10.82 1.14 35.8 0.75Jalari endada Fore shore 47.03 16.28 1.56 2.08 1.56 0.54 29.99 0.96Jalara peta Fore shore 26.24 18.86 1.43 1.63 9.44 0.68 40.86 0.86

Table2.3 Weight Percentage of Heavy Minerals in 230+ FractionStation Environment Sillimanite Garnet Epidote Zircon Monazite Rutile opaque UnknownNerellavalasa Dune 0.39 0.35 0 4.91 0.52 0.52 91.21 2.1Kotturu Dune 1.68 1.67 0 3.42 0 0.92 90.25 2.06Hamsavaram Dune 2.24 1.3 0 3.02 0 0.92 90.54 1.97Rushikonda Dune 3.36 2.23 0 3.72 0 1.19 87.62 1.88Endada Dune 1.56 1.55 0 3.17 0 0.85 91.08 1.79Appughar Dune 2.44 2.16 0 2.15 0 0.18 91.34 1.73Jalari endada Dune 6.29 5.57 0.28 0.75 0.17 0.52 84.79 1.64Jalara peta Dune 2.1 4.72 0 1.13 0.35 0.69 89.42 1.59

Station Environment Sillimanite Garnet Epidote Zircon Monazite Rutile opaque UnknownNerellavalasa Back shore 4.44 5.74 1.02 0.69 0.79 1.1 84.45 1.76Kotturu Back shore 16.69 1.15 0.92 0 0 0.49 79.11 1.65Hamsavaram Back shore 0 0 0 0 0 0 0 0Rushikonda Back shore 0 0 0 0 0 0 0 0Endada Back shore 12.24 1.74 1.39 4.78 1.09 0.16 77.11 1.49Appughar Back shore 2.7 0.85 0.27 3.87 0.51 0.51 89.9 1.39Jalari endada Back shore 7.7 1.36 0.55 2.95 0.17 0.51 85.45 1.31Jalara peta Back shore 5.51 4.56 0.78 0.7 0.16 0.16 86.86 1.27

Nerellavalasa Fore shore 2.36 7.44 0.26 0.89 0 1.31 86.63 1.1Kotturu Fore shore 4.82 4.04 1.08 1.64 0.17 0.17 87.13 0.97Hamsavaram Fore shore 0 0 0 0 0 0 99.13 0.87Rushikonda Fore shore 5.25 1.57 0.14 0 0.52 0.52 91.26 0.76Endada Fore shore 6.82 6.09 0.79 0.89 0 0 84.7 0.71Appughar Fore shore 4.77 4.97 0.27 1.11 0.17 0.68 87.56 0.47Jalara endada Fore shore 7.81 4.25 0.41 1.1 0 0.34 85.74 0.36

D I S C U S S I O N SIn the study area the concentration of Heavy minerals varies in different size fractions of

the sediments, and an inverse relationship was noticed between gain sizedataandweightpercentage of the heavy minerals. Among the Heavy minerals, Opaques (Ilmenite+Magnetite) have higher concentration than Non – opaque they contain more than 50% ofHeavy minerals based on the weight percentage. In Non – opaque component Sillimanite and Garnets are the major proportions. Rutile, Epidote, Spinel, Zircon, Monazite, and Sphene are also present in some locations with very minor proportions. Opaques and Zircons are sourced from number of Rock types such as Acidic, Basic Igneous rocks. Garnets, Sillimanite, Bluish green Hornblende are typical in High rank metamorphic rocks like Pyroxene Granulites and Khondalites (Pettijohn, 1956). Rutile is from Basic Igneous rocks or from Reworked sediments; Monazites are characteristic of Acid Igneous rocks and Pegmatites, they are also derived from Charnockite. Major source of Zircons is from Charnockite rather than Khondalites (Viswanathan, 1965; Siddiquie and Viswanathan, 1968). This combination of minerals in the study area indicates that the “Provenance is a mixture of High grade Metamorphic and Igneous terrains”.

The major portion of total heavy mineral content was concentrated in the fine fraction (+230). The heavy mineral concentration as fine grained indicates that the selective transport of heavies by littoral currents, and waves from the adjacent ephemeral river inputs. The high concentration of opaques in fine fraction and some minerals like garnets Get concentrated in the coarse fraction. Indicates that different processes control the Concentration in different microenvironments. The concentration of heavy minerals in dune environment from Jalara peta to endada coastal sands is more pronounced due to physical differentiation by wind action. Concentration of heavies in dunes was reported by Komar and Wang, 1984; Kidwai and Wagle, 1975; Nayak, 1997; Reddy and Prasad, 1997. The concentration of heavies in back shore is influenced by the both Aeolian and marine action. The winnowing processes continuously effect the backshore region, the Concentration of heavies in this zone is function of wave energy flux and sand grain size (Jones et al., 1973). But in the foreshore regions, where marine influence is dominant, the upper foreshore region has higher concentration which gradually decreases towards lower foreshore. The upper foreshore which is continuously affected by swash and back wash processes. Because of this panning action at upper foreshore heavy minerals get concentrated and lighter minerals transported and get deposited in lower foreshore region. Similar observations were recorded by Komar and Wang (1984), Reddy and Prasad,(1998) and Hanamgond and Chavadi, (1999).

C O N C L U S I O N SIn this investigation, each heavy mineral was examined under the microscope toDetermine its type its percentage with in the mineral sample and the origin of each mineral.In each sample the minerals proved to be more or less similar provenance.1. In conclusion, assemblages of the heavy minerals are derived mainly from metamorphic suite or rocks (i.e.,) Eastern Ghats group of rocks and minor proportion from igneous rocks.2. Sediment grain size and heavy mineral weight percentage have inverse proportion. And they are highly associated with the fine fractions i.e. Very fine sand.3. The weight percentage of Illmenite and Sillimanite increases as the grain size decreases and also the weight percentage of garnet is in coarse fraction and it decreases as the grain size decreases.4. The distribution and concentration of heavy minerals were controlled by physical properties of heavy minerals, grain size of sediment and oceanographic conditions.5. Interpretation of data sets indicates that the Coastal sediment are well sorted and shows both positive and negative Skewness patterns. Basing on the Skewness (Positive) patterns it can be said that they belong to depositional episode.6. More opaques are observed in (+230) fraction of the sediments in study area.7. Among dune, back shore and fore shore environment high concentration of the heavy minerals are observed in Back shore and upper fore shore environments.8. The concentration of the heavy minerals decreases from left to right as, opaques, Sillimanites, Garnet, Zircon, Epidote, Monozite and Rutile and some of the other minerals like pyroxene, amphiboles and micas etc. in the study area.

ACKNOWLEDGEMENT: The authors are thankful to head of the department for providing necessary facilities. I Thankful to K. Sagar (L&T InfoTech, Chennai) and Y. Arun kumar Technical analyst, Dassalt company, Hyderabad. support direct and indirectly in this project.

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