Chronology of red dune aggradations of South India and its Palaeo-environmental significance

Abstract

Abstract:Red sand dunes occur in the coastal plains of south east and west of Tamil Nadu, India between the co-ordinates of 8°00' to 9°30' N; 77°18' to 79° 00' E. OSL dating of these sands indicated aggradations between ~16-9 ka and ~9-3 ka in the west and east coasts respectively. Dating results from inland red dunes at the foothills of Western Ghats show a break in deposition at ~6 ka and aggradation since ~2 ka. The sand aggradations in the west coast occurred during the transition period when SW monsoon in the area was re-establishing. The dunes attained their stability by 9 ka. In the coastal region, the aggradations were controlled by sea level changes and a local recycling of earlier dunes (in the east coast). In the inland areas, the dune building was controlled by sand supply from fluvial sources.

Coastal landscape evolution in the Wilpattu National Park (NW Sri Lanka) linked to changes in sediment supply and rainfall across the Pleistocene–Holocene transition

“…Comparison of red dune sedimentary records from Sri Lanka (a: this study; d: Singhvi et al, 1986) and Tamil Nadu (b: Jayangondaperumal et al, 2012; c: Alappat et al, 2013, 2016) and their correlation with records of palaeo‐monsoon activity in Sri Lanka (e: Ranasinghe, Ortiz, Smith, et al, 2013; g: Premathilake & Gunatilaka, 2013) and with regional (1: Rein, Lückge, & Sirocko, 2004; Khider, Stott, Emile‐Geay, Thunell, & Hammond, 2011; 2: Kessarkar, Rao, Naqvi, & Karapurkar, 2013; 3: f: Tiwari, Ramesh, Somayajulu, Jull, & Burr, 2005) and global climatic events. The green vertical lines indicate radiometric ages and the dashed curves show the eustatic (A: Lambeck, Rouby, Purcel, Sun, & Sambridge, 2014) and regional (B: Katupotha, 2015) sea‐level records for the last deglaciation and Holocene [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…In southeastern Tamil Nadu, calcrete of the Poochikkadu Series is unconformably overlain by red sands (Teri Sands) that are considered as an equivalent of the Red Beds in Sri Lanka (Alappat et al, 2013; Jayangondaperumal et al, 2012; Wallace, 2016). As in Tamil Nadu, the calcrete succession at Point Kudrimalai (Bed 3) is terminated by an erosive surface with pronounced topography (Figures 1, 3, 5a and 6a).…”

“…The white modern dunes along the coast in this area formed since 2.3 ± 0.2 ka when the relative sea level stabilized at the present level and the region became persistently semi‐arid (Figure 7; Banerjee, 2000; Jayangondaperumal et al, 2012; Joseph et al, 1997; Joseph, Thrivikramji, & Anirudhan, 1999). In southwestern Tamil Nadu (Muttom area), a second stage of dune accretion (Terrace II) and subsequent reddening was identified at 4.5 ± 0.5 ka (Figure 7) and interpreted as the result of sand deposition in the backshore region also associated with a relative sea‐level highstand (Alappat et al, 2013, 2016). In Figure 7, we correlate the episodes of Near‐coastal Teri and Terrace II dune formation with the relative sea‐level curve of Sri Lanka (Katupotha, 2015) and it seems that these episodes of aeolian activity in southern coastal India coincide with relative sea‐level lowstands, which increased the source areas for sand at the coast, rather than with relative sea‐level highstands.…”

“…The basic concept in interpreting the depositional history of the red fossil dunes is that periods of sand accumulation are related to (semi‐)arid climatic conditions and the reddening occurred when the climatic conditions became more humid with enhanced precipitation (Gardner & Martingell, 1990). More recently, it has been shown that dune development in the coastal area of eastern Tamil Nadu was linked not only to dry climatic conditions but also to wind strength and supply or availability of sediment, controlled by vegetation cover and sea‐level changes (Alappat et al, 2016; Alappat, Seralathan, Shukla, Thrivikramji, & Singhvi, 2013; Jayangondaperumal, Murari, Sivasubramanian, Chandrasekar, & Singhvi, 2012; Kunz, Frechen, Ramesh, & Urban, 2010). Red palaeo‐dunes are widely distributed in the coastal area of South China (Old Red Sand) as well and have been used there as palaeo‐climate archive for investigating variations in the East Asian Winter Monsoon intensity during the late Quaternary (Hu et al, 2013).…”

Origin and Paleoenvironmental Significance of the Old Red Sand Along the Southeast Coast of China

“…Coastal dunes are common around the world and resulted from complex interactions related to prevailing winds, sand supply, climate changes and sea level fluctuations (Blumer et al, 2012). Red dunes are widespread in south Asia and east Asia, including Sri Lanka, India and the southeast coast of China, etc (Alappat et al, 2013). The "Old Red Sand" (ORS) refers to a Quaternary sediment of semi-cemented medium fine sand, mainly in red or brown red, and intermittently distributed along the southeast coast of China, its thickness can reach several meters to tens of meters (Wu et al, 1995;Zeng et al, 1999a;Li et al, 2012;Jin et al, 2018).…”