Rhizosphere: A fascinating paleovegetational and paleoclimatic new intermediary in the Quaternary fluvio-lacustrine set-up of the Purna alluvial basin, central India
Introduction
A preliminary investigation regarding the rhizospheres, a rounded to sub-rounded, calcretized, organo-sedimentary structures, is being hypothesized for the first time by reporting the same from the Quaternary fluvio-lacustrine sediments of Purna alluvial basin, central India. Initial studies on concretions and nodules of CaCO3, formed in various sedimentary environments, have been endeavored over a century back to facilitate identification and classification of the same (Barrel, 1913; Kindle, 1923), however, over the recent past years, these structures are to a great extent being investigated for paleoclimatic recreations (Srivastava, 2003; Achyuthana et al., 2007; Jha et al., 2020). Klappa (1980), for the first time, exhaustively reviewed the concretion created structures and authored the term ‘rhizolith’ particularly for the cylindrical bodies of the same and further revealed their five different types based on the shape, structure, and appearance, i.e., i) root molds, ii) root casts, iii) root tubules, iv) rhizocretions, and v) root petrifactions. As per Retallack (2001) and Kraus and Hasiotis (2006), there are two unmistakable varieties of rhizoliths i.e., drab holed root mottles and rhizohalos that are likely delivered by the anaerobic disintegration of buried organic matter. Based on the various approaches, Little and Field (2003) put forward these organo-sedimentary structures, addressed chiefly by rhizoliths and rhizospheres, are the participants of regoliths.
Another term ‘megarhizolith’ was designated by McNamara (1995) for a large calcified root framework facilitating columnar features from the Nambung National Park of Australia. Accreditations with regards to the term ‘mega’ for the large columnar structures exposed at the Canary Island have also been made by Alonso-Zarza et al. (2008). Accordingly, they opined that both rhizospheres and megarhizoliths are the common structures that have been noted from various sedimentary successions across the globe, however, overlooked and misinterpreted to date (Genise et al., 2011). Genise et al. (2011) considered rhizospheres as independent structures, however, certain similarities exist with the rhizoliths including their associated structures and advocated their formation by both living and dead plants especially in parched, semi-arid, and sticky environments. The rhizoliths having frequent occurrences in the basin area, are likewise well investigated from many other river settings of the Indian sub-continent and elsewhere and deciphered as a critical intermediary to comprehend climatic and monsoonal prevalences during the Quaternary period (Achyuthana et al., 2007, 2012; Williams et al., 2009; Agrawal et al., 2014; Bhattacharyya et al., 2014). Nonetheless, purposefully, it can not be precluded that the preservation of rhizospheres in the fluvio-lacustrine sediments of the Indian subcontinent, may be even in entire Asia, has yet not been reported even though these alluvial sediments of the continent witness extensive, multidimensional research works.
The basin being scrutinized has been addressed to issues up to specific limitations in the past to understand climate during the Quaternary period based on certain geological identities closely related with the climatic conditions of the region, i.e., Youngest Toba Tuff (YTT, ca 75 ka) (Srivastava and Singh, 2019a, b, 2020, 2021; Srivastava et al., 2020), vertebrate fossil remains (Thakur et al., 2018) and calcretes (Srivastava and Bansod, 2019; Srivastava et al., 2019, 2021). Nonetheless, still there are various issues in our insight from different perspectives including climatic reproduction. Our present focus on the rhizosphere is primarily due to its first report from India that may be extendable to entire Asia. Accordingly, we, hereby, tried to lay out a fundamental endeavor to comprehend the paleovegetation and paleoclimate in the basin area by detailing the rhizospheres. Present investigation works with its identification, morphological categorizations, lithological affiliations, and sidelong profiling.
Section snippets
Study area
The study area of the Purna basin, limited by 200 100 to 210 410 N and 760 00 to 770 550 E, constitutes a total area of 18,514 km2, of which, 6522 km2 is the alluvial tract distributed in the central part, whereas, the rest is covered with low to moderately and at places, highly dissected, basaltic terrain of the Deccan Trap (Kale, 2010). The alluvial store is predominantly areno-argillaceous, however, rudaceous lithounits are likewise perceptible. Stratigraphically, the succession consists of
Studied localities and their lithological set-ups
To explore the lithological set-ups and sedimentological ascribes, total 13 sites have been examined along the Purna river course viz., Kodori (77041′58″ E, 21016′49″ N), Kural (77040′30″ E, 21013′38″ N), Masod (77039′17″ E, 21013′41″ N), Asegaon (77034′40″ E, 21008′38″ N), Kholapur (77030′18″ E, 21057′14″ N), Parad (77016′02″ E, 20051′10″ N), Wadad (77007′39″ E, 20051′50″ N), Kapileshwar (77006′45″ E, 20051′31″ N), Gandhigram (76059′38″ E, 20052′02″ N), Andura (76051′09″ E, 20053′18″ N),
Macromorphology of rhizospheres
The intend to do macromorphology of rhizospheres was led for their detailed field investigations including preservational attributes, reasonable assortment, categorization, detailing of external features, photodocumentation, etc. These structures are represented by light gray to grayish-brown colored, lithified, solid to compact, calcretized bodies of 7–20 cm diameters. In specific cases, it shows a hole or notch of 3–5 cm diameter on the top. Infrequently, abundant, small-sized rhizoliths or
Lithological association, origin and depositional environment
The paleosols, having the rhizospheres, are represented by reddish-yellowish brown, mottled, massive to faintly laminated beds, constituting together a column of 3–5 m thickness in almost entire basin area (Srivastava et al., 2020) and has been assigned as Lower Pleistocene in age (Tiwari et al., 2010). Traditionally, the paleosols, have been widely portrayed as marker horizons because of having preservations of shreds of evidence related to environmental and climatological cycles along with
Conclusions
The rhizospheres in the Purna alluvial basin have been reported for the first time in the Indian subcontinent that are plentifully preserved in the paleosols of the Quaternary time frame. It has been hypothesized that the same is formed in the specialties created by the exercises between living and decaying plant roots and fungi. Later on, these were calcified with the solutions leached out from the host or encompassing rocks under the arid to semi-arid climate in the basin area. Based on the
Submission declaration and verification
We authors, hereby, declare and verify that the work described has not been published or submitted previously to any journal and has been approved by all authors. If the manuscript is accepted, it will not be published elsewhere in the same form either in English or in any other language including electronically without the written consent of the copyright holder.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work is financially supported by Science and Engineering Research Board (SERB), New Delhi, India in the form of a major research project (SB/S4/ES-692/2013) awarded to AKS. Thanks are extended to Dr. Mangla Bansod for her help in the preparation of line diagrams.
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Carbonate cementing minerals in rhizoliths from Badain Jaran Desert: Implication for pedo-diagenesis and environment of dune soil
2023, RhizosphereCitation Excerpt :Vaterite crystals have a hexagonal structure, and aragonite crystals show an orthorhombic structure, while calcite crystals present a rhombohedral structure (Liendo et al., 2022; Jimoh et al., 2018). Investigating the micro-morphology of calcium carbonate in soils, sediments and rocks can help in reconstructing past environmental conditions (Alonso-Zarza, 2018; Verrecchia and Verrecchia, 1994; Monger et al., 1991) The occurrence and morphology of pedogenic carbonates, including size, shape and distribution are valuable indices of pedo-environments and pedogenic processes (Singh and Srivastava, 2021; Golubtsov et al., 2021; Nyachoti et al., 2017; Durand et al., 2018; Diaz-Hernandez et al., 2018; Milliere et al., 2019; Eren et al., 2018). Calcium carbonate found specially in rhizosphere microecosystems shows a unique relationship with several factors such as organic matter, micro-organism and plant distribution, as well as moisture and leaching processes (Huguet et al., 2021; Casado et al., 2014; Becze-Deák et al., 1997).
Had Youngest Toba Tuff (YTT, ca. 75 ka) eruption really destroyed living media explicitly in entire Southeast Asia or just a theoretical debate? An extensive review of its catastrophic event
2022, Journal of Asian Earth Sciences: XCitation Excerpt :They proposed that the plains were covered with mixed C3-C4 plants between 80 and 20 ka duration, however, dramatic increase in C4 vegetation around 45 ka has been noticed as revealed by 13C values of C3 fatty acid. Remains of vegetational activity i.e., rhizospheres and rhizoliths have also been reported from the paleosol horizons developed in entire pre-tephra succession at the Kapileshwar locality of the Purna alluvial basin, Central India (Srivastava and Singh, 2019a, b; Singh and Srivastava, 2021). During further course of field work, the authors have found out preservation of rhizospheres and rhizolith, restricted to the silty-clayey paleosols of 3–5 m thickness, constituting lower part of the pre-tephra succession in entire alluvial basin that acts as a marker horizon (Srivastava et al., 2021).
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