Quartz surface microtextural studies of Cauvery River sediments, Tamil Nadu, India
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ORIGINAL PAPER
Quartz surface microtextural studies of Cauvery River sediments, Tamil Nadu, India Natarajan Gobala krishnan 1 & Raghavendramurthy Nagendra 1 & Lakshmanan Elango 1
Received: 1 April 2015 / Accepted: 9 June 2015 # Saudi Society for Geosciences 2015
Abstract The spatially distributed sand samples of the Cauvery River sediments in Tamil Nadu were investigated with respect to their surface microtextural features in north-east (NE) and south-west (SW) monsoon rainfall seasons. The quartz grains show distinct surface microtextures with unique mechanical, chemical and morphological features with respect to the sedimentation process. The mechanical features like conchoidal fractures with arcuate steps indicate that the sand grains were derived from crystalline rocks. The abundance of angular grains supports that the grains were transported long distance by fluvial process. The silica globule, overgrowth and precipitation marks on the grain surfaces decipher the chemical process in silica saturated environment. Similarly, the solution pits in sand grains near Poombugar indicate the influence of sea water. The chatter mark trails suggest the wet tropical climate. The abundance of mechanical features and smooth surface microtextures suggest that the grains were transported in high-energy conditions. The NE monsoon sediments are coarse grained to medium grained and SW monsoon sediments are medium to fine sand size, which are attributed to the high and moderate energy conditions, respectively.
Keywords Quartz . Surface microtextural feature . Cauvery River
* Natarajan Gobala krishnan [email protected] * Raghavendramurthy Nagendra [email protected] 1
Anna University, Chennai, Tamil Nadu, India
Introduction The surface microtextural features of quartz grains are helpful in the interpretation of the sedimentary environments and potential transport mechanisms (Krinsley and Marshall 1987; Helland and Diffenda 1993; Mahaney et al. 2001, 2004; Alekseeva and Houndslow 2004). The mechanical and chemical processes affect the sediments during the transportation (Al-Saleh and Khalaf 1982), thus modifying the grain surfaces. The microstructure of the surface of the sand grain is a reflection of the depositional environment, and it helps to differentiate fluvial, marine, aeolian and glacial environments (Chakroun et al. 2009; Newsome and Ladd 1999). The sediments of Cauvery River have been studied with respect to their chronology (Alappat et al. 2010), chemical composition and suspension matter (Dekov, et al. 1997), heavy metal fraction in surface sediments, distribution of heavy metals (Dhanakumar et al. 2013; Venkatesh Raju et al. 2012; Vaithiyanathan et al. 1992), REE geochemistry of recent clastic flood plains (Sharma and Rajamani 2001) and palaeoflood records (Alappat et al. 2010). However, focus has not been on the microtextural studies of the Cauvery River sediments. This study records the surface microtextural features of the spatially distributed detrital quartz (sand) grains in the Cauvery River, Tamil Na
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