Elsevier

Palaeoworld

Volume 29, Issue 3, September 2020, Pages 490-511
Palaeoworld

Organic walled microfossils from the Neoproterozoic Owk Shale, Kurnool Group, South India

https://doi.org/10.1016/j.palwor.2019.08.002Get rights and content

Abstract

An assemblage of organic walled microfossils (OWM) of 17 taxa belonging to 10 genera is reported from the Neoproterozoic Owk Shale of the Kurnool Group, South India. The assemblage comprises sphaeromorphs, colonial aggregates, filamentous forms, spiral cylindrical filaments belonging to cyanobacteria, problematic acanthomorphic acritarchs, Netromorphic, Sphaeromorphic and Acantomorphic groups. The assemblage includes cyanobacteria: Siphonophycus kestron, S. robustum, S. typicum, S. solidum, Polytrichoides lineatus; Netromorphic acritarch: Arctacellularia tetragonala, Navifusa majensis, Jacutianema solubila; Sphaeromorphic acritarch: Ostiana microcystis, Synsphaeridium spp., Leiosphaeridia minutissima, L. tenuissima, L. crassa, L. jacutica, L. ternate; and Acanthomorphic acritarch: Cavaspina aff. C. acuminata and Variomargosphaeridium aff. V. litoschum. The age conundrum of Kurnool Group (Mesoproterozoic versus Neoproterozoic) is discussed. On the basis of the reported OWM assemblage the age of the Kurnool Group is established as Neoproterozoic.

Introduction

Proterozoic microfossils not only provide a major source of palaeontological information, essential for understanding early life and evolution, but are also helpful in biostratigraphic correlations and palaeoenvironmental reconstructions of the Proterozoic successions (Butterfield and Chandler, 1992, Knoll et al., 2006, Sergeev et al., 2008, Sergeev et al., 2012, Knoll, 2009, Baludikay et al., 2016, Loron, 2016, Javaux and Knoll, 2017). The assemblage of microfossils comprising eukaryotes, colonial forms, processed acritarchs and spiral forms reveal the steps in the evolution, innovation, and patterns of diversification of different clades of life (Moczydłowska, 2005, Javaux, 2011, Butterfield, 2015, Javaux and Knoll, 2017). In the absence of absolute dating of Proterozoic sedimentary successions, some characteristic and index microfossils are used as a suitable tool to decipher the age of the fossil-bearing strata. In comparison to the Palaeoproterozoic fossil assemblages, microfossils of the Neoproterozoic Era (1000–541 Ma) are better preserved, diversified and quantitatively abundant (Butterfield and Chandler, 1992, Zang and Walter, 1992a, Zang and Walter, 1992b, Butterfield et al., 1994, Knoll et al., 2006, Sergeev et al., 2008, Sergeev et al., 2012, Knoll, 2009, Baludikay et al., 2016, Loron, 2016, Javaux and Knoll, 2017). The palaeobiological assemblages of the Neoproterozoic Era are characterized by the advent of large acritarchs, diversification of eukaryotes, the origin of multicellular individuality, and the occurrence of megascopic life and bio-mineralization (Moczydłowska, 2005, Javaux, 2011, Butterfield, 2015, Javaux and Knoll, 2017). Sixty years ago, the discovery of rich microfossil assemblages from the Neoproterozoic Bitter-Springs Formation of central Australia opened the window for microfossils studies (Schopf, 1968, Schopf and Blacic, 1971). Subsequent studies of the Neoproterozoic successions in different parts of the world revealed the diversity of biological forms present in the varied ecosystems of this era (Schopf, 1968, Schopf and Blacic, 1971, Knoll et al., 1991, Butterfield et al., 1994, Hofmann and Jackson, 1994, Knoll, 1996, Samuelsson, 1997, Sergeev and Schopf, 2010, Tang et al., 2015, Loron, 2016, Porter and Reidman, 2016).

In the southern part of India, two Proterozoic basins, the Kurnool and the Bhima are considered to be coeval as they have similar alternating clastic and carbonate successions (Figs. 1, 2). The Owk Shale of the Kurnool Group is correlated with the Halkal Shale of the Bhima basin. Laminated bands and nodules of the phosphorites are present both in the Owk Shale and the Halkal Shale at the similar stratigraphic level, which corroborates the fact that coeval sedimentation took place in these basins. Both these basins are traditionally regarded as Neoproterozoic (Raman and Murty, 1997; Sharma and Shukla, M., 1999; Ramkrishnan and Vaidyanathan, 2008; Sharma and Shukla, Y., 2012, 2016). The age of the Kurnool Group has been inferred to be <1.1 Ga. This age is assigned on the basis of (i) correlation of angular unconformity between the Cuddapah Supergroup and the Kurnool Group and occurrence of the diamondiferous Banganapalle Conglomerate at the base of Kurnool Group (King, 1872, Meijerink et al., 1984, Dongre et al., 2008, Chalapathi Rao et al., 2010a, Chalapathi Rao et al., 2010b); (ii) discovery of Obruchevella which prominently occurs in Ediacaran sediments (Sharma and Shukla, 2012, Sharma and Shukla, 2016) and poorly preserved Ediacaran Complex Acanthomorph Palynoflora (ECAP) type acritarchs from the Owk Shale. The occurrence of helically coiled microfossil Obruchevella and newly discovered fragments of ECAP acritarchs from the Owk Shale (Sharma and Shukla, 2012, Sharma and Shukla, 2016) together with the burrow structures in the underlying Narji Limestone (Arya and Rao, 1979) convincingly indicate a Neoproterozoic age for the Kurnool basin and challenge the otherwise assigned Mesoproterozoic age of the basin (Dongre et al., 2008, Chalapathi Rao et al., 2010a, Chalapathi Rao et al., 2010b). In the past, a few micropalaeontological studies were conducted on the Kurnool basin (Salujha et al., 1972, Sharma and Shukla, 2012, Sharma and Shukla, 2016). A detailed systematic palaeontological approach is, therefore, needed to constrain the age of the Kurnool basin and assess the importance of the assemblage in understanding evolutionary status.

The present work attempts to study the distribution of the microfossils and their biostratigraphic implications for the Kurnool basin. It is the first ever detailed systematic palaeontological investigation of the organic-walled microfossils preserved in fine-grained siliciclastic sediments of the Owk Shale of the Kurnool Group, south India. The study reveals a diverse and well-preserved assemblage of organic-walled microfossils, comprising filamentous and coccoidal microfossils and acritarchs, many of them are reported for the first time from the Kurnool basin.

Section snippets

The tectonic setting and stratigraphic framework

Cresent shaped configuration of rocks is prominently visible on any geological/geomorphological map or satellite imagery of India. This distinct geological feature noted in the southern part of the country is known as the Cuddapah Supergroup (Fig. 1a). King (1872) provided the first lithostratigraphical account of the rocks present in the Cuddapah basin which subsequently underwent the comprehensive revisions in the twentieth century (Meijerink et al., 1984, Nagaraja Rao et al., 1987). Broadly,

Material and methods

The Owk Shale exposed on the eastern part of the hillock 1445 situated in the village Ankireddipalle (15°07′N, 78°03′E) and Petnikota areas of the Kurnool district of Telangana state yielded fossils described in this paper. The exposed thickness of the Owk Shale at these localities is about 15 m and samples were collected through entire succession. Shale samples were macerated using a combination of standard and modified maceration methods devised by Grey (1999). Organic residues were mounted as

Systematic palaeontology


Cyanobacteria
Genus Siphonophycus Schopf, 1968, emend. Knoll and Golubic, 1979, emend. Knoll et al., 1991
Type species: Siphonophycus kestron Schopf, 1968.
Description: Unbranched, non-septate cylindrical filaments of different widths and broken ends sometimes with rare septa, occasionally solitary, but mostly gregarious in tangled masses.
Remarks: Siphonophycus tubes are considered as empty sheaths of Lyngbya, Phormidium and Plectonema (LPP) types of cyanobacteria (Rippka et al., 1979, Knoll and

The affinity of the Owk Shale assemblage

The Owk Shale contains abundant organic-walled microfossils of moderate diversity as well as common Proterozoic macrofossil compressions such as Chuaria circularis Walcott, 1899 (Sharma and Shukla, 1999). We have established an additional assemblage of distinct entities belonging to 17 taxa and 10 genera (Fig. 7), largely of sphaeromorphic and netromorphic acritarchs, ECAP and numerous remains of filamentous and coccoidal cyanobacteria. Large and distinctive filamentous and morphologically

Conclusions

The Neoproterozoic age of the Owk Shale microbiota is confirmed by the present study in recording the acanthomorphic acritarchs and four species of Obruchevella that are characteristic entities of Neoproterozoic and early Cambrian deposits. It is further supported by previously reported the late Neoproterozoic composition of the carbonaceous mega-remains and possible worm burrows in the lithostratigraphic unit underlying the Owk Shale. The entire assemblage clearly indicates its Neoproterozoic

Acknowledgements

We are grateful to the Department of Science and Technology, Government of India (INT/RUS/RFBR/P-278) and Russian Federation of Basic Research (RFBR 17-55-45081-IND) for supporting our studies. We are thankful to Dr. Qing Tang and an anonymous reviwer who made several constructive suggestions on our previous version of the manuscript. We acknowledge the permission by the Birbal Sahni Institute of Palaeosciences to publish this work (BSIP\RDCC\55-2018-19) and Directors of the BSIP and Geological

References (155)

  • A.M.J. Meijerink et al.

    Stratigraphic and structural development of the Precambrian Cuddapah Basin, SE India

    Precambrian Research

    (1984)
  • M. Moczydłowska

    Taxonomic review of some Ediacaran acritarchs from the Siberian Platform

    Precambrian Research

    (2005)
  • M. Moczydłowska

    The Ediacaran microbiota and the survival of Snowball Earth conditions

    Precambrian Research

    (2008)
  • M. Moczydłowska

    New records of late Ediacaran microbiota from Poland

    Precambrian Research

    (2008)
  • M. Moczydłowska et al.

    Ediacaran radiation of organic walled microbiota recorded in the Ura Formation, Patom Uplift, East Siberia

    Precambrian Research

    (2012)
  • J. Samuelsson et al.

    Organic-walled microfossils from the Proterozoic Thule Supergroup, Northwest Greenland

    Precambrian Research

    (1999)
  • V.N. Sergeev

    Microfossils in cherts from the Middle Riphean (Mesoproterozoic) Avzyan Formation, southern Ural Mountains, Russian Federation

    Precambrian Research

    (1994)
  • V.N. Sergeev

    The distribution of microfossil assemblages in Proterozoic rocks

    Precambrian Research

    (2009)
  • N.J. Butterfield

    A vaucheriacean alga from the middle Neoproterozoic of Spitsbergen: implications for the evolution of Proterozoic eukaryotes and the Cambrian explosion

    Palaeobiology

    (2004)
  • N.J. Butterfield

    Early evolution of the Eukaryota

    Palaeontology

    (2015)
  • N.J. Butterfield et al.

    Palaeoenvironmental distribution of Proterozoic microfossils, with an example from the Agu Bay Formation, Baffin Island

    Palaeontology

    (1992)
  • N.J. Butterfield et al.

    Paleobiology of the Neoproterozoic Svanbergfiellet Formation, Spitsbergen

    Fossils and Strata

    (1994)
  • N.V. Chalapathi Rao et al.

    Carbonate xenoliths hosted by the Mesoproterozoic Siddanpalli Kimberlite cluster (Eastern Dharwar Craton): Implications for the geodynamic evolution of southern India and its diamond and uranium metallogenesis

    International Journal of Earth Science

    (2010)
  • N.V. Chalapathi Rao et al.

    Petrogenesis of the Mesoproterozoic lamproites from the Krishna Valley, Eastern Dharwar craton, southern India

    Precambrian Research

    (2010)
  • P.A. Cohen et al.

    Large spinose microfossils in Ediacaran rocks as resting stages of early animals

    Proceedings of the National Academy of Science, USA

    (2009)
  • A. Combaz

    Un Microbios du Trémadocien dans un Sondage ďHassi-messooud

    Actes de la Société Linnéenne de Bordeaux, Série B

    (1967)
  • K.L. Cotter

    Neoproterozoic microfossils from the Officer Basin, Western Australia

    Alcheringa

    (1997)
  • A.R. Crawford et al.

    The age of the Cuddapah and Kurnool Systems, southern India

    Journal of the Geological Society of Australia

    (1973)
  • A. Dongre et al.

    Limestone xenolith in Siddanpalli Kimberlite, Gadwal Granite-Greenstone Terrain, Eastern Dharwar Craton, Southern India: Remnant of Proterozoic platformal cover sequence of Bhima/Kurnool age?

    Journal of Geology

    (2008)
  • C. Downie et al.

    On the interpretation and status of some Hystrichosphaera genera

    Palaeontology

    (1963)
  • A. Eisenack

    Microfossilienausdem Ordovizium des Baltikums. 1. Markasitschicht, Dictyonema-Scheifer, Glaukonitsand, Glaukonitkalk. Senckenbergian

    Lethaea

    (1958)
  • A. Eisenack

    Mikrofossilienausdem Silur Gotlands. Hystrichosphären, Problematika

    Neues Jahrburch für Geologie und Paläontologie Abhandlungen

    (1965)
  • T.R. Fairchild

    Size as a criterion for distinguishing probable eukaryotic unicells in silicified Precambrian microfloras

    Paleontologia et Estratigraphia

    (1985)
  • R.A. Fensome et al.

    Acritarchs and fossil prasinophytes: an index to genera, species and intraspecific taxa

    (1990)
  • M.B. Gnilovskaya et al.

    Pre-Ediacaran fauna from Timan (Annelidomorphs of the Late Riphean)

    Stratigraphy and Geological Correlation

    (2000)
  • I.N. Golub

    A new group of problematic microstructures in Vendian deposits of the Orshansk basin (Russian Platform)

  • E.Y. Golubkova et al.

    Lower Vendian microfossil assemblages of East Siberia: significance for solving regional stratigraphic problems

    Stratigraphy and Geological Correlation

    (2010)
  • V.K. Golovenok et al.

    The microfossils in the cherts from the Riphean deposits of the Turukhansk Uplift

    Stratigraphy and Geological Correlation

    (1993)
  • J.W. Green et al.

    Microfossils from silicified stromatolitic carbonates of the Upper Proterozoic Limestones–Dolomite ‘Series’, Central East Greenland

    Geological Magazine

    (1989)
  • K. Grey

    A modified palynological preparation technique for the extraction of large Neoproterozoic acanthomorph acritarchs and other acid-insoluble microfossils. Western Australia Geological Survey Record 1999/10

    (1999)
  • K. Grey

    Ediacaran palynology of Australia. Memoirs of the Association of Australasian Palaeontologists 31

    (2005)
  • T.N. Hermann

    Findings of mass accumulations of trichomes in the Riphean

  • T.N. Hermann

    Organic World Billion Year Ago

    (1990)
  • T.N. Hermann et al.

    On the nature of the Precambrian microfossils Arctacellularia and Glomovertella

    Paleontological Journal

    (2008)
  • H.J. Hofmann et al.

    Shale-facies microfossils from the Proterozoic Bylot Supergroup, Baffin Island, Canada

    Memoir, The Palaeontological Society

    (1994)
  • R.J. Horodyski

    Middle Proterozoic shale-facies microbiota from the lower Belt Supergroup, Little Belt Mountains, Montana

    Journal of Paleontology

    (1980)
  • T.V. Jankauskas

    New algae from the Upper Riphean of the southern Ural Mountains and Cis-Ural

    Paleontological Journal

    (1980)
  • T.V. Jankauskas

    Microfossils of the Riphean in the southern Urlas

  • T.V. Jankauskas

    Plant microfossils of the Urals

  • Cited by (0)

    1

    Deceased.

    View full text