INTRODUCTION
Floodplains are regions of land adjacent to a river that stretches from the channel’s banks to the foot of the valley’s surrounding walls and is subjected to flooding during times of heavy flow with soil composition made up of clays, silts, sands, and gravels that have been left behind by floods. Due to their high soil fertility, they deposit nutrients and water in the form of organic matter and helped to provide some significant agricultural regions, such as the Mississippi river basin and the Nile (Aslan, 2003; Kovács, János, 2013). Fluvial geomorphological and biological processes both pioneer in shaping river landscapes (Aslan, 2003; Gurnell et al., 2012; van Oorschot et al., 2016; Kleinhans et al., 2018; Kleinhans et al., 2019). Due to the fertile nature of the soil and freshwater availability, both agricultural and urban sectors grow close to or on floodplains, the large rivers such as the Ganga, the Mississippi, and the Nile are typical examples (Aslan, 2003; Singh 1996; Tandon and Sinha, 2007; Jain and Tandon, 2010; Kovács, János, 2013;). The Ganga Basin along with its different tributaries is a magnificent example of a floodplain region with numerous geomorphic features in a foreland basin (Singh 1996; Tandon and Sinha, 2007; Jain and Tandon, 2010). Due to the high agriculture, urbanisation, with surface and ground water systems, the basin is well known on a global scale for its potential at variable scales. When paired with geomorphological information, the palynofacies (particulate organic matter) is an effective analytical tool that is used to evaluate the depositional environment and the potential for producing hydrocarbons (older successions) in both contemporary and historical samples (Traverse, 1994; Tyson, 1995; Batten 1996; Sebag et al., 2006; Mendonça Filho et al., 2011a; Carvalho et al., 2013; Mueller et al., 2014; Thakur et al., 2019). The analysis of palynological organic matter (palynofacies), entails a comprehensive examination of all aspects of the sediment, including the identification of the various particulate constituents and evaluation of their absolute and relative proportions, particle sizes, and preservation statuses (Sebag et al., 2006; Mendonça Filho et al., 2011a).
The term ’palynofacies’ was coined by Combaz (1964) and describes the total assemblage of particulate organic matter contained in sediments and sedimentary rocks after removing the carbonates and silica. Later, Tyson (1995) introduced the idea of modern palynofacies and its applied elements to identify a particular group of environmental importance and their relationship to hydrocarbon potential. Palynofacies is a significant unsoluble portion of the biotic component in any sedimentary environment, providing crucial information for interpreting process-driven changes both naturally and anthropogenically (Traverse, 1994; Sebag et al., 2006; Mendonça Filho et al., 2011a; Sridhar et al., 2020; Xenopoulos et al., 2021) enabling us to recognize, measure, and evaluate the state of preservation (Traverse, 1994; Tyson, 1995; Sebag et al., 2006; Mendonça Filho et al., 2011a). For multi-dimensional investigations such as climate change, hydrodynamic conditions, oxic-anoxic habitats, run-off-related processes, proximal-distal trends, palaeoenvironments, and archaeology study, both in continental and marine records, it is currently acknowledged as a reliable proxy (Tyson and Follows, 2000; Hoaen, 2000; Closas et al., 2005; Carvalho et al., 2013; Mueller et al., 2014; Sridhar et al., 2020) along with addressing the taphonomical biases (Tyson, 1995; Batten, 1996; Prasad et al., 2007; Prasad et al., 2013). The epicontinental samples and deposits of marine origin have been extensively studied using palynofacies and organic geochemistry techniques from Paleozoic (Mendonça-Filho, 1999; Mendonça Filho et al., 2011a), Mesozoic (Carvalho et al., 2006a; Iemini et al., 2007), and Cenozoic rocks (Del Papa et al., 2002; Menezes and Mendonça, 2011a). Principally it aids in inferring depositional environments from sedimentary/ lithofacies which may be unfossiliferous. When interpreting the mechanisms governing deposition, they also aid in understanding sedimentary sequences and developing sequence stratigraphic framework (Prasad et al., 2013).
Sebag et al. (2006) provide a detailed review of the major approaches for palynofacies characterization in recent terrestrial environments and is based on applied examples in surface deposits, soil profiles, wetlands, lacustrine ecosystems, and within catchments.
The present study takes into account the palynofacies constituents and sediment texture analyses on the surface sediments from the flood plain of the Gomati River to analyse the fate of biotic components. The modern analogue will serve as a representation of the sediment texture, distribution, and conservation of palynofacies. It looks for subtle variations in palynofacies and sediment texture variability in an environment with fluvial system (mostly the meandering stage). The goal is to comprehend the recent to sub-recent sediments from flood plain zones of Gomati River that are influenced by anthropogenic and natural factors. Their variation and correlation are related to environmental conditions and aims to gauge changes in the depositional system in the flood plains of the Gomati River in the Lucknow district, Uttar Pradesh, India. The study aims to ratify the modest changes of palynofacies that have not yet been explored in fluvial system studies elsewhere in the terrestrial domain. The Ganga plain, where the Gomati River runs, has very fertile soil since antiquity. With examples like Hulas Khera, Hariharpur, Zoharganj, Gopalpur, Saraiya, Brahamanpur, Krishnapur, and many more, it has also benefited archaeology (Upadhyay, 2019). Establishing human activities in the Middle Ganga Plain requires a major effort with integrated study of proxies such as palynofacies and sediment texture and others. The study also looks into the utilisation of ratios of burned and degraded charcoal, as well as cuticle and tracheids, to define the degradation and deterioration of organic matter in urban to suburban reaches. The processes governing the transport, deposition, and degradation of palynofacies in the terrestrial system and their fate by natural and anthropogenic agents, needs to be established (Tyson, 1995; Medeanic and Silva, 2010; Mendonça Filho et al., 2011a; Hoaen, 2000).