Heavy Minerals and Granulometric Studies in Coastal Sediments from Keelakarai to Periyapattinam, Gulf of Mannar, East Coast of India (original) (raw)
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Journal of Sedimentary Environments, 2020
Placer mineral deposits and their limited occurrence have gathered worldwide attention for researchers and geologists to exploit new areas of deposition. This research aims to know the transportation and depositional environment of sediments, provenance and distribution of heavy minerals between Besant Nagar and Sathurangapattinam in the coastal region of Tamil Nadu (India). The sediment samples are collected for textural analysis, magnetic susceptibility (MS), petrographical and mineralogical (XRD) studies of sediment samples, including the heavy minerals studies. Grain size analysis showed fine to medium-grained sandy sediment with very well to moderately sorting indicate reworking of beach edges accompanied by unimodal to the trimodal distribution of sediment from the riverine and marine environment. Grains are mostly symmetrically skewed with platykurtic to leptokurtic nature, indicating low-to high-energy environment prevailing in the region where the deposition and erosion are equally balanced in the area. Bivariate and one percentile-median (CM) pattern plots indicated that most of the sediment is deposited by beach processes transporting sediment by bottom suspension and rolling. The amounts of magnetic or iron-bearing minerals are high in locations no. 1 (Besant Nagar beach), 5 (Injambakkam beach) and 12 (Tiger cave beach) interpreted using MS studies, whereas the heavy mineral weight percentage is higher in locations no. 11 (Pattipulam beach) and 12 (Tiger cave beach). The correlation plot of Heavy wt% vs MS showed positive correlation and in general plots deciphered that the locations with high wt% (Besant Nagar, Injambakkam and Tiger cave beach) showed higher MS indicating the presence of magnetic minerals and the correlation plot between individual mineral grain count% vs MS explicated that the locations were rich in magnetic minerals like ilmenite, magnetite (opaques) and epidote (medium magnetic). The petrographical study of heavy mineral and XRD analysis revealed that the study area contained a high percentage of opaques, garnet, zircon, rutile, chlorite, sillimanite, hypersthene, hornblende, tourmaline, possibly derived from charnockites, granulite gneiss, migmatites and basic dykes. The overall investigation concludes that the sediments are distributed at various locations by marine processes depositing sediment rich in magnetic and heavy minerals derived from various rock type sources transported by rivers and later driven by longshore currents of oceans flowing from S to N, N to S during different months and SW-NE monsoon play a vital role in the distribution of beach placers.
Integrated offshore investigations along selected segments off East Coast of India for port and harbors developmental activities have provided detailed information on the sea floor morphology and sediment characteristics. The data permits comparative evaluation of the region from northern parts to southern parts. The eastern continental margin of India is flanked by a narrow zone of onshore, offshore sedimentary basins with a sediment fill ranging from Early to Late Holocene. There are variations in sediment nature and geotechnical characteristics along the near shore sector of the east coast. An attempt is made to compare the geotechnical characteristics of the sediments in the near shore sector of the east coast along Andhra Pradesh and Pondicherry coasts. Detailed studies at port areas have been carried out by the East Coast Operations, Marine Wing, GSI, Visakhapatnam at selected sectors along the Andhra Pradesh and Pondicherry coasts for their development and also on case specific studies for single buoy mooring etc.
Thiruchendur coast of southern Tamilnadu, India has been studied for grain-size spectrum and textural parameters namely mean, sorting, skewness and kurtosis. The grainsize spectrum shows a marked variation in the berm, high tide line (HTL) and low tide line (LTL) stretches. Variation in energy condition is controlled by geomorphology of the sedimentary beach. Textural pattern shows complicated profile as a result of the fluctuation in the physicochemical conditions due to the sediments and the marine interactions. Abundance of the medium sand to fine sand shows the prevalence of comparatively moderate-to low-energy condition in the Thiruchendur area. Linear discriminate function of the samples indicates an aeolian, shallow marine deposition environment and less influence of fluvial (7 %) process. CM diagram (C 0 one percentile in microns M 0 medium in microns) of Thiruchendur coast sediments suggests that deposition takes place by (1) rolling, (2) bottom suspension, (3) graded suspension. This is also supported by the wave energy in different stretches in beach line and also tractive current figure implies the sediments disturbed by the tractive and turbidity currents. The heavy minerals are concentrated in the berm (average, 11.8 %) and high tide line (average, 11.2 %) because of highenergy condition and aeolian action. Quartz microtextures show the mechanical action due to high-energy condition in Manapad and Kuduthalai areas, the chemical action because of to low-energy condition along the Thiruchendur, Kallamozhi areas.
A study on sediments depositional mechanism at Nayakankuppam coast, Tamilnadu, India
Textural analysis carried out for the sediments of the Nayakkankuppam coast revealed that inlet part is dominated by fine sand, central part is dominated by medium sand and outlet part is dominated by coarse sand. The grain size parameters namely Mean size (MZ), standard deviation (σ1), skewness(Ski), and kurtosis (KG) of percentile values derived from the cumulative curves following Folk and Ward and the moment technique based upon grouped data are most widely used. It is observed that in Nayakkankuppam, most of the samples were fallen in the moderately well sorted to well sorted nature. Skewness measures asymmetry of frequency distribution and marks the position of mean with respect to median. The fine skewed nature of the sediments clearly exhibits sediment input from various sources of tributaries. The finely skewed nature is also implies a low velocity than normal, this skewness data indicated that the sediments are nearly symmetrical to fine skewed, the median class of the sediments dominate almost throughout their distribution. The kurtosis data indicated Mesokurtic to platykurtic. The CM pattern divulged that the sediments were transported bottom suspension and rolling as well as graded suspension. The comparison with the tractive current diagram, the berm samples fall in beach environment, the remaining samples fall in beach and tractive current environment.
Journal of Radiation Research and Applied Sciences, 2014
The main objectives of the present study are to understand the heavy mineral distribution, trace elemental distribution and to study the variation, if any, between the grain size and trace elemental distribution within the beach. Totally 20 stations have been collected and weight percentage of heavy minerals are identified. In the present study area most of the sands are fine and medium grained, indicates beach environment and most of the grains are positively skewed. The study area contained a high percentage of orthopyroxene (hypersthene) and garnet, rounded and broken zircons inferred to have been derived from charnockites and granulite gneiss of the study area. Overall from the geochemistry studies, it is observed that the Ni and Cr are more dominant and higher concentration in Panayar (station no. 2), Mahabalipuram (station no. 6), Kalpakkam (Station no. 7) and Perunthuravu (station no. 8). The present study has clearly indicated the multiple roles of tectonically controlled coastal blocks and their geomorphological influence in redistributing the sediments with favourable NEeSW configuration and wave energy conditions must have contributed to the formation of heavy minerals in a particular zone.
2023
The Chinnavilai and Erayumanthurai beach sediments of the Kanyakumari District consist of medium-grained, moderately well-sorted, unimodal, occasionally bimodal, mesokurtic, leptokurtic and platykurtic. The fine skewed and symmetrical nature of sediments implies the prevalence of high and low energy, entailing a mixed distribution of coarse and fine sediments. The washing and backwashing of waves cause the coarser sediments to retainment and entrapped amidst finer sediments. The heavy minerals distribution reflects that the less content in Erayumanthurai samples, whereas the Manavalakurichi, Enayam, Kurumpanai sediments comprise >60%. The oval shape zircon is devoid of inclusions, whereas, the euhedral zircons comprise subhedral inclusions. Distinct fractures in zircons are caused due to transportation by waves and currents. The garnet and zircon grains are well-rounded, implying the source for these sediments are an admixture of medium to high-grade metamorphic rocks, reworked sediments, charnockite, and granite gneisses.
The successive phases of marine transgression and regression, the aeolian, fluvial and beach processes are considered to be responsible for the varied nature of landscape of the coastal belt of Tamilnadu. The nature of sediments deposited are mainly a function of the type of coast, coastal morphology as well as the energy condition and energy fluctuations through space and time under which it has been deposited. Granulometric studies of the vertical pit samples reveals that in the Poompuhar region there is predominance of moderately well sorted fine sand. The sediments of Ambanar River Mouth region showed predominant fine sand, with predominant very well sorted to well sorted sediments. The skewness value shows that samples are mostly nearly symmetrical. The samples are mesokurtic to platykurtic in nature of distribution. In Tarangambadi region predominance of fine sand, exhibits moderately well sorted to well sorted sediments. Sediments are coarse skewed to near symmetrical and are leptokurtic to mesokurtic. Sediments at Poompuhar exhibit shallow marine condition in a fluvial/deltaic environment deposited under aeolian processes. But the sediments at Tarangambadi and Ambanar River Mouth exhibit aeolian/ beach processes under shallow marine turbid environment. .
International Journal of Engineering Research & Technology (IJERT), 2020
https://www.ijert.org/x-ray-diffraction-patterns-for-quantitativeanalysis-of-coastal-sediments-in-betweenmandapam-and-vembar-gulf-of-mannar-coast-south-india https://www.ijert.org/research/x-ray-diffraction-patterns-for-quantitativeanalysis-of-coastal-sediments-in-betweenmandapam-and-vembar-gulf-of-mannar-coast-south-india-IJERTV9IS040212.pdf Quantitative analysis was carried out to determine the major and minor constituent minerals present in sediment samples collected at the coastal region between in Mandapam and Vembar, Gulf of Mannar coast, South India by XRD technique. The grain-size distributions of sediments are studied in the study of grain size in relation to mechanism of sediments deposition. The composition of the coastal sediment is dominated by medium to fine sand. The distribution pattern and textural parameters of sediments vary regionally in the Ramanathapuram coastal sediment distribution. Based on the texture of sediments it can be said that the beach consists of medium to fine sand was domains. Sedimentological studies reveal that depositional patterns in the beach are mostly controlled by fluvial and marine processes. The deposition of medium to fine sands in the extreme in our study area attributed to the discharge Vembar and Gundar Rivers. Further, the representative sediment samples were analyzed by XRD technique to yield more information about the minerals. X-ray diffraction methods were non-destructive and can be used in the identification of mineralogical composition. These results confirmed that the applied techniques are relatively quicker and more reliable in mineral analysis. The X-Ray diffraction sediments sample analysis proved that the minerals of calcite, quartz, orthoclase, microcline, biotite, hypersthene, hornblende, albite, anorthite sepiolite, illite, chlorite, halloysite Montmorillonite, halite and heavy mineral garnet, zircon, sillimanite, topaz, cobaltite, kyanite, magnetite, hornblende and ilmenite. The followed by minerals are derived from Recent Alluvium and Southern Granulite Terrain in India.
Depositional environment of sediments along the Cuddalore coast of Tamilnadu India
Surficial sediments of beaches along the Cuddalore, central coast of Tamilnadu from Ponnaiyar estuarine to Thirumulaivasal were studied for their textural parameters namely Mean (Grain size) phi, Standard deviation, Skweness and Kurtosis and mineral percentages. Observed variation of energy conditions are controlled by the fluvial profile in the river channel. Textural analysis of medium sand shows the existence of comparatively high energy condition in the marine environment and low energy conditions in the fluvial zone. Linear Discriminant Function (LDF) analysis of the samples indicates a shallow marine environment origin for most of the samples and very few numbers of samples originated from fluvial environment. Heavy mineral content serves as an index for stratigraphic correlation of unfossilferrous strata. The lowest heavy mineral content indicates progradational activity and low energy wave conditions. These results show that reworked sediments, submerged during the Holocene marine transgression are being deposited on present day beaches by waves, currents and rivers in the study region.
Hydrodynamic Processes and Heavy Mineral Deposits of the Southwest Coast, India
The beaches of Chavara and Manavalakuruchi of the southwest coast of India have rich heavy mineral concentrations with distinctive spatial and temporal distributions. Both locations exhibit high concentrations of heavy minerals on the northern sides of the headlands, with practically no concentration on the southern sides. Cross-shore, the sediments become less rich in the heavy minerals offshore. During the rough monsoon when the winds are onshore the concentration of heavy minerals along the mid-tide line of the beaches is considerably higher than during the calm non-monsoon when swell prevails. The concentrations of heavy minerals alongshore were highest in zones where the beach with relict sediments of high mineral content is eroding. We find that the patterns observed in the heavy minerals along the Chavara coast can be explained by a single hypothesis dependent on the presence of a source and the winnowing of the more easily entrained low-density fractions. The pattern appears to be slightly different for Manavalakuruchi coast where the zone of hundred percent enrichment is adjacent to the river mouth, indicating an additional source of river input. Analysis of wave and current data showed the dominant role of waves over coastal currents in the transport of these sediments and the wave-induced thresholds for initiation of motion indicated that the heavy component is less easily moved than the white sand (quartz) constituent. We suggest that the patterns can be explained by winnowing of the white sands from the eroded beach sediments during the stormy monsoon leaving higher enrichment at the beach. In the swell period of the post-monsoon, the erosion ceases as the asymmetric swells re-establish the beach, bringing proportionally more of the more-easily entrained white sediment shorewards, thereby explaining the reduced enrichment at this time. The cross-shore reduction in heavy minerals may be simply explained as an inverse relationship to distance from the beach source. The longshore distribution is a response to the presence of the source of black sands on the northern sides of the headlands. The headlands may simply act to isolate the source, thereby explaining the tendency for high concentrations on one side only.