Fossil bacteria from the Permotriassic Trappean strata of Siberia

46

ISSN 0031-0301, Paleontological Journal, 2009, Vol. 43, No. 8, pp. 46–54. © Pleiades Publishing, Ltd., 2009.

INTRODUCTION

The most ancient rocks which contain biomorphicmicrostructures have been recorded in the Archeangreenstone belts of western Greenland, South Africa,and Australia (Knoll and Barghoorn, 1977; Walter,1983; Schopf, 1983, 1993; Knoll, 1994; Westall andWalsh, 2002). These sections are dominated by volcan-ogenic and volcanogenic–sedimentary matter. Basedon the association of rocks, lithologic–facies and pale-ovolcanological data on the Archean belts, it has beenestablished that the comatiites–quartz arenites–stroma-tolites association corresponds to shoal conditions andthe pillow–basalts–turbidites association correspondsto more deepwater parts of the basins (Kozhevnikov,2000). Manifestation of microbial life is frequentlytightly connected with the boundaries of volcanogenicmatter and water.

It should be noted that a proportion of near-surfacelayers of the Earth are volcanic and almost all of themare exposed to either constant or temporary influence ofwater. The volcanogenic matter–water boundary sur-face is capable of maintaining various microbial com-munities that live along the surfaces, cracks, andbreaks. Microbes live both on the surface of wet cracksand drill inside the rock, producing burrows. Microbialactivity in igneous rocks produces characteristicchanges in volcanic glass and silicate matter. Depres-sions, tunnels, and irregular boundaries between theglass and palagonite (chlorite-like matter varying incomposition) are formed. The tunnels sometimes pene-trate for 200

µ

m deep into the glass and occasionallydisplay structures resembling cells ranging from 1

µ

mto several microns in diameter (extant material) (Fisket al., 1998). Tunnels are singular, branching, with

smooth-faced or irregularly pitted walls (Fisk et al.,2006a, 2006b; McLoughlin, 2007).

Microbial forms connected with pillow lavas,including extant (Fisk et al., 2006a), Early Proterozoic(Astafieva et al., 2008), and even Archean (Furnes et al.,2004) forms, have recently been studied. Therefore, thestudy of cyanobacterial and bacterial formations in volca-nogenic and volcanogenic–sedimentary matter of any ageis of great interest. The study of rocks from the regions ofthe trappean volcanism is particularly attractive.

Note that all Precambrian stromatolites have beenrecorded in ancient greenstone belts and they are tightlyconnected in distribution with the lava–water boundary.The oldest finds (3.5–3.2 Ga) come from the greenstonebelts of the Barberton Mountains in South Africa andSwaziland and the Pilbara Region in western Australia,with the prevalence of extensive sequences of mafic–ultramafic volcanic rocks, interbedding with sedimen-tary rocks, which were deposited during breaks in effu-sive activity. Presumed bioremains in these greenstonesections are mostly preserved in interbeds of silicifiedsediments in volcanic sections and include carbonaterocks, which contain in places structures resemblingfossilized cocci and filaments, deteriorated microbialmats, and stromatolites (Lowe, 2006). Thorough stud-ies have recently shown that these remains are confinedto certain conditions, and presumed mats, or, more pre-cisely, cyanobacterial films, are restricted to oceanicwaters, within the photic zone. Recent studies suggestthat organisms typical of these conditions includedanoxygenic photoautotrophic organisms, which inhab-ited oceans with a surface temperature of

±

55–85

°

C(these temperatures are reconstructed based on model-ing the data on oxygen isotopes) (Knauth and Lowe,2003). However, other speculations suggest that, at that

Fossil Bacteria from the Permotriassic Trappean Strata of Siberia

M. M. Astafieva

a

, A. Yu. Rozanov

a

, G. N. Sadovnikov

b

, and E. V. Sapova

a

a

Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997 Russiae-mail: [email protected]

b

Russian State Geological Prospecting University, ul. Miklukho-Maklaya 23, Moscow, 117873 Russia

Received April 15, 2008

Abstract

—The strata of the Permotriassic Trappean Complex of Siberia (Ilimpeya River and Kapchan locality)are studied. The water–lava and water–tuff boundaries are shown to be promising for bacterial paleontologicalstudies. The analysis of fossilized microbial communities shows that they vary depending on sedimentationconditions. This example is important for a better understanding of the prospects for the study of similar situa-tions in the Archean and Proterozoic.

DOI:

10.1134/S0031030109080085

Key words

: Stromatolites, microbes, bacteria, cyanobacterial mats, acritarchs, trappean complex.

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FOSSIL BACTERIA FROM THE PERMOTRIASSIC TRAPPEAN STRATA OF SIBERIA 47

time (3.5 Ga), the temperature was much lower, about40

°

C, and oxygen was necessarily present in the atmo-sphere (Rozanov, 2006).

We examined trappeans of Siberia, which weredated to the Triassic (

Resolution

…, 1981) or Permian(Sadovnikov and Orlova, 1994, 1997). They occupiedvast areas of central and northern parts of Western andCentral Siberia. In the opinion of one of the authors, theformation of volcanic plateaus of Siberia started at theend of the Late Permian. Near the Permian–Triassicboundary, the range of volcanites considerably increased,involving the whole of the Tunguska Syneclise, the Pla-teau continuously increased in height and exceeded1700 m (Fig. 1).

Fossil bacteria have been recorded in two regions.The first find was in the southeastern Tunguska Synec-lise, on the right bank of the Ilimpeya River (large left

tributary of the Nizhnyaya Tunguska River in its middlestream), 1.6 km upstream from the mouth of its largeleft tributary, the Dyukunna River. The volcanogenicformations are represented by the KonvunchanianGroup, which includes the Yuzhnochunskaya, Chichi-kanskaya, and Limptekonskaya formations (Table 1).Near the mouth of the Dyukunna River, there is mostlythe upper part of the Chichikanskaya Formation, whichis represented by greenish gray, gray, and dark graymedioclastic tuffs, with the fragments consistingmostly of light gray vitrobasalts interbedding with redhematite–carbonaceous matter, with a fine undulatinglaminated texture resembling stromatolites. Samplingwas performed in broken plates of red hematite–car-bonaceous matter.

The second find was on the southern slope of theKhatanga Depression at the lower reaches of the Kotui

Kara Sea

Tiksi

TuraNizhnyaya Tunguska

Olenek River

Vilyui River

Angara River

Lena River

Lake Baikal

100 110 120

0 400 800 km

1 2 3

8070

6090

60

130

140

70

Laptev Sea

Taimyr Peninsula

Norilsk

Kot

ui R

iver

Yeni

sei

Khatanga

Fig. 1.

The scheme of distribution of the Trappean Formation in central Siberia: (

1

–

2

) boundary of the distribution of volcanites:(

1

) in the Vyatkian Age (within most of the range, tuffs); (

2

) in the Taimyr Age (within most of the range, lavas); and (

3

) records ofbacterial communities.

48


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ASTAFIEVA et al.

River, on its left bank in the Kapchan (Truba) locality,between the mouths of the Ostuolba and Estilyakh riv-ers. Deposits of the Konvunchanian and Putoranagroups are exposed here. The Putorana Group is repre-sented by the Kogotoks Formation, which is composedof black basalt, forming a thin cover usually with well-pronounced mandelstone zones. The samples with fos-sil bacterial communities come from gray thin-layersiliceous inclusions in a basalt cover of the middle partof the Kogotoks Formation. These lenses are probablyfragments of sedimentary rock that was formed beforean eruption and was then broken off by a lava flow, wasengulfed by it, and then ascended in it.

The samples were studied with the aid of a Cam-Scan-4 scanning electron microscope, with a Link-860microanalyzer. Various biomorphic microstructureswere recognized, differing in the samples from tuffo-genic matter of Chichikanskaya Formation (IlimpeyaRiver) and from basalts of the Kogotoks Formation(Kapchan).

(1) Rocks on the right bank of the Ilimpeya River arebrick-red hematite–carbonaceous, with a complexundulating laminated texture, which is represented byalternation of peculiar cycles (Pl. 1, figs. 1, 2). In thechemical composition of these strata, calcium and iron(in varying proportions) prevail; in addition, silicon andaluminum are frequently present (Fig. 2).

Each cycle consists of alternating interbeds of fila-mentous biomorphic microstructures separated fromeach other by interbeds of clayey particles. The fila-mentous microstructures are usually covered with gly-cocalyx (Pl. 1, figs. 3–6).

The surface of each cycle is covered by a crust,which is probably composed of clayey particles. Some-times, the clayey surface is covered with the presum-ably fossilized biofilms, or the glycocalyx.

It should be noted that the microstructures from thetrappean strata are similar to the figures obtained by oneauthor of this paper (E.V. Sapova) during the study offossilization of cyanobacteria in clays (Pl. 2, figs. 1–5).

Table 1.

Stratigraphic chart of volcanogenic deposits in the eastern volcanic plateau of the Siberian Platform

Series Stage Horizon Group

Formation

AnabarRegion

Tunguska Syneclise

eastern southeastern

Tatarian? Taimyrian

Putorana PutoranaKogotoks

Kochechum –Kapchan

KhungtukunIgodekitsk

LimptekonskayaPirdinskaya

TatarianVyatkian Lebedev Tuton-

chan Korvuchansk KayalakhskayaChichikanskaya

Yuzhnochunskaya

Severodvinian Gagar’eostrovsk – Potokoisk Gagar’eostrovsk

Si

Au

Ca

Ca

Fe

Aug. 20, 2004

T-P SiberiaJ1925 ‹9phone

Aug. 20, 2004

T-P SiberiaJ19 03phone

Fe

Fe

Ca

Ca

Au

SiAl

Fig. 2.

Chemical composition of hematite–carbonaceous rocks on the right bank of the Ilimpeya River.


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Experiments on the fossilization of cyanobacteriawere performed both with mixed cultures of

Oscillato-ria terebriformis, Phormidium

sp., and

Mastigocladus

sp. and a culture of

Microcoleus chthonoplastes.

Thesecultures were grown on various media at a temperatureof 28–30

°

C and light exposure of 4–5 klx and were

treated variously by wet clay (smectite). The materialobtained was examined using a SEM (CamScan-4).

The pictures obtained during experiments arealmost identical to the samples from trappeans,although mineralization of both living and dead bacte-ria occasionally results in the development of mineral

1000

µ

m 1000

µ

m

100

µ

m 10

µ

m

3

µ

m 3

µ

m

(a) (b)

(c) (d)

(e) (f)

Plate 1

E x p l a n a t i o n o f P l a t e 1

Figs. 1 and 2.

Specimen PIN, no. 5082/1, (SEM, points 53 and 00, Aug. 26, 2004); alternation of peculiar cycles in rick-red hema-tite–carbonaceous matter; lamination in general view (up to ten layers) is seen.

Fig. 3.

Specimen PIN, no. 5082/1 (SEM, point 43, Aug. 25, 2004); magnified picture of one cycle.

Fig. 4.

Specimen PIN, no. 5082/1 (SEM, point 37, Aug. 25, 2004); crust overlapping a cycle, which is presumably composed ofclayey particles and probably covered by fossilized glycocalyx.

Fig. 5.

Specimen PIN, no. 5082/1 (SEM, point 39, Aug. 25, 2004); external surface of an underlying layer, which is probably alsorepresented by glycocalyx.

Fig. 6.

Specimen PIN, no. 5082/1 (SEM, point 42, Aug. 25, 2004); filamentous structures of an underlying cycle.

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ASTAFIEVA et al.

structures differing considerably from the initial condi-tion characteristic of living cells.

The photographs provided show the structuresclosely resembling trichomes of cyanobacteria in size.These structures are covered with leaflike scales, whichare probably formed of clayey minerals. Most of the

photographs show the same structural elementsarranged chaotically.

An important role in biomineralization is played bythe formation in unfavorable conditions by cyanobacte-ria of a protective cover (glycocalyx). The glycocalyxconsists mostly of polysaccharides, a substance towhich various mineral particles adhere, including

10

µ

m(a) 10

µ

m(b)

10

µ

m(c) 10

µ

m(d)

3

µ

m(e) 3

µ

m(f)

Plate 2


Figs. 1 and 2.

Mixed culture of the filamentous trichomic cyanobacteria

Oscillatoria aeroginosa

and

Phormidium

sp., obtainedthrough fossilization (material provided by E.V. Sapova).

Fig. 3.

Mastigocladus

sp. (material provided by E.V. Sapova).

Fig. 4.

Specimen PIN, no. 5082/1 (SEM, point 13, Aug. 26, 2004); filamentous microstructures of an interbed of hematite–carbon-aceous matter.

Figs. 5 and 6.

Specimen PIN, no. 5082/1 (SEM, points 19 and 21, Aug. 25, 2004); filamentous microstructures of an interbed ofhematite–carbonaceous matter.


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clayey particles. The pictures of the mixed culture of

Oscillatoria aeroginosa

and

Phormidium

sp. (Pl. 2,figs. 1, 2) obtained through fossilization of filamentoustrichomic cyanobacteria are closely similar to the fila-mentous microstructures covered by the glycocalyx,obtained in the present study (Pl. 2, figs. 3, 4). The pic-tures of

Mastigocladus

sp. (Pl. 2, fig. 5) show the same

filamentous microstructures as in an interbed of hema-tite–carbonate matter (Pl. 2, fig. 6).

Thus, it is possible to say rather confidently that thematter in question was probably formed under a consid-erable biogenic influence. The layers represented by fil-amentous microstructures, separated from each otherby biofilms or thin clayey interlayers, correspond to the

3

µ

m(a) (b) 10

µ

m

3

µ

m 3

µ

m

10

µ

m 3

µ

m

(c) (d)

(e) (f)

Plate 3


Figs. 1–3.

Specimen PIN, no. 5081/3 (SEM, points 15, 16, and 22, Sept. 6, 2004); acritarch-like microstructures.

Fig. 4.

Specimen PIN, no. 5081/3 (SEM, point 29, Sept. 6, 2004); coccoid structures, about 3

µ

m in diameter, surrounded by gly-cocalyx.

Fig. 5.

Specimen PIN, no. 5081/3 (SEM, point 04, Sept. 6, 2004); fragment of a filament about 3

µ

m in diameter, immersed in bio-film.

Fig. 6.

Specimen PIN, no. 5081/3 (SEM, point 02, Sept. 6, 2004); section of biofilm showing that they probably consist of coverscomposed of fossil coccoid structures at most 3

µ

m in diameter.

52


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ASTAFIEVA et al.

development or growth of filamentous cyanobacteria.As environments became unfavorable, cyanobacteriaprobably intensified the secretion of glycocalyx (hence,increasing adherence of clayey particles to bacteria). Asfavorable conditions returned, cyanobacteria continuedthe growth and a new layer in the cycles under studywas formed.

It is known that communities of microorganisms formstructures of certain morphology. It is possible to use thissynmorphology as a diagnostic character, including iden-tification of fossil specimens. It is possible to apply thisprinciple to any microbial community. This concerns stro-matolites and bioherms (Zavarzin, 1993).

We deal with a layered organogenic stromatolite-like structure. The structures investigated resemble fos-sil “cyanobacterial mats,” i.e., relict prokaryotic com-munities, which are usually compared to flat stromato-lites. They are most similar in morphology and size toArchean and Early Proterozoic mini- and microstroma-tolites (Hofmann, 2000; Raaben, 2005).

At present, cyanobacterial mats are preserved inextreme habitats, where the development of higherorganisms is complicated, in places of active volcanicactivity, littoral parts of seas, and dried basins, withhigh salinity and alkalinity (Gerasimenko and Zavar-zin, 1993).

Both halophilic and thermophilic cyanobacterialmats are benthic populations of microorganisms domi-nated by phototrophic bacteria, of which cyanobacteriaare the basic producers of organic matter and responsi-ble for the structure of mats. The physical and chemicalgradients within the mat, produced by vital functions ofthe microfloral community, result in vertical zonationof the mat.

All cyanobacterial communities form a distinct lam-inated structure, with distinctive alternation of thedevelopmental zones of certain microorganism groupsand mineral interlayers. Each community irrespectiveof its habitat usually contains three zones: aerobic, withthe development of cyanobacteria; strictly anaerobic,with the development of sulfidogenes and methano-

genes; and intermediate, with the development of facul-tative aerobes (Gerasimenko and Zavarzin, 1993;Zavarzin, 2003). The sulfate reduction in the lower(anaerobic) zone of the mat results in the deposition ofsulfides of poorly soluble heavy metals, primarily ofiron (Zavarzin, 1984).

In our case, chemical analysis shows the absence ofsulfur compounds, in particular, sulfides in the matterunder study; no framboidal structures have been foundeither. Consequently, it is impossible to take thesestructures for cyanobacterial mats in the strict sense ofthe word because the lower zone corresponding to theanaerobic zone of extant mats, which is characterizedby the development of sulfides, is absent or not pre-served. Nevertheless, the presence of fossilized glyco-calyx, distinct lamination of the structures in question,and their general pattern suggest that the stromatolite-like structures from the Permotriassic trappeans ofSiberia are a fossil “reduced cyanobacterial mat,” alaminated structure consisting of layers of cyanobacte-ria and clayey interlayers, or a thick cyanobacterial film.

(2) Fossil bacterial communities from the Kapchanlocality were found in samples from gray thin-layer sil-iceous inclusions in the middle part of the KogotoksFormation in a basalt cover, mostly in its massive lowerpart. In contrast to the samples from the right bank ofthe Ilimpeya River, the samples from Kapchan lackstructures corresponding to cyanobacterial formations(communities), which are characteristic of rocks fromthe right bank of the Ilimpeya River; an overlying layerof clayey particles is also absent.

In the samples from this locality, we have recordedacritarch-like structures (Pl. 3, figs. 1–3; Fig. 3). Theyare small spherical forms from 3 to 15

µ

m in diameter,with an uneven surface, which is presumably covered byglycocalyx. Accumulations of these structures under athick layer of a biofilm (?) are also observed (Pl. 3, fig. 3).

In addition, there are coccoid structures about 3

µ

min diameter surrounded by glycocalyx (Pl. 3, fig. 4).These structures are also covered with a thick layer ofpresumably silicified biofilm. The chemical composi-

M Al

Si

Au FeMg

AuCa

Si

Sept. 6, 2004Kapchan Zh-36globule 15 Sept. 6, 2004

Kapchan Zh-36globule 16

Fig. 3.

Chemical composition of siliceous rocks and fossilized microorganisms from the middle part of the Kogotoks Formationof Kapchan.


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tion of all samples from Kapchan consists of siliconwith an admixture of iron.

Filamentous forms are almost absent. It is possibleto presume the presence of a filament in the only case(Pl. 3, fig. 5). This is a fragment about 3

µ

m in diameter,which is also covered by a thick biofilm.

The sections of the structures (Pl. 3, fig. 6) regardedas biofilms show that they probably consist of layers offossil coccoid forms at most 3

µ

m in diameter.

CONCLUSIONS

Our study shows that contacts between tuff (lava)and water in volcanic regions provides favorable condi-tions for the development of bacterial communities andoccurrence of fossilized bacterial structures in the geo-logical record. The character of microbial communitiesin volcanic regions changes depending on conditions.Shallow-water marine communities connected with thepillow lava display all components of cyanobacterialmats, including cyanobacteria, purple bacteria, andframboidal structures (Astafieva et al., 2008). In theregions of trappean volcanism and associated continen-tal basins, conditions for the life of cyanobacteria wereprobably somewhat different. Thus, almost all volcano-genic rocks, particularly volcanogenic–sedimentaryrocks, are rather promising with reference to the dis-covery of fossil bacterial structures. Therefore, the factthat the earliest rocks of the Earth are mostly composedof volcanogenic matter should not be regarded as anobstacle in the search for fossil bacteria.

ACKNOWLEDGMENTS

We are sincerely grateful to L.M. Gerasimenko,E.L. Sumina, G.T. Ushatinskaya, and E.B. Naimark forvaluable advice and discussions of the manuscript andto A.V. Kravtsev and L.T. Protasevich for help with theCamScan-4 scanning electron microscope.

This study was supported by the Program of the Pre-sidium of the Russian Academy of Sciences “Origin ofthe Biosphere and Evolution of Geo-biological Sys-tems” (Subprogram 2), by the Russian Foundation forBasic Research, project no. 08-04-00484, and by the Pro-gram of the President of the Russian Federation for Sup-port of Leading Scientific Schools (NSh-4207.2008.5).

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Fossil bacteria from the Permotriassic Trappean strata of Siberia