Columnar stromatolites of the terminal Precambrian Porsanger Dolomite and Grasdal Formation of Finnmark, north Norway
JANINE BERTRAND-SARFATI & ANNA SIEDLECKA
Bertrand-Sarfati, J. & Siedlecka, A.: Columnar stromatolites of the terminal Precambrian Porsanger Dolomite and Grasdal Formation of Finnmark, north Norway. Norsk Geologisk Tidsskrift, Vol. 60, pp. 1-27. Oslo 1980. ISSN 0029-196X.
Nine horizons of algal stromatolites have been recognized in the Porsanger Dolomite: one new group, Gaaradakia, and five new forms, Line/la akkaniella, Eleonora laponica, Gaaradakia jacutophytonica, Line/la trollina and Inzeria sinopivarra are described. In the Grasdal Formation, lithostratigraphic correlative of the Porsanger Dolomite, three horizons of algal stromatolites are recognized and o ne new form described, Minjaria tana. The stromatolite assemblage of both formations is in general suggestive of a late U pper Riphean/V endian age. However, the Porsanger Dolomite and Grasdal F ormation have no stromatolite forms in common and it is tentatively concluded that the Grasdal Formation is slightly younger than the Porsanger Dolomite. The Porsanger Dolomite contains some stromatolite forms similar to !hose of the Eleonore Bay Group of East Greenland and the upper Middle Hecla Hoek of Spitsbergen. Affinities with Late Precambrian stromatolite assemblages of the USSR are Iimited.
J. Bertrand-Sarfati, Centre Geologique et Geophysique, Universite des Sciences, 34060 Montpellier, CEDEX, France. A. Siedlecka, Norges geologiske undersøkelse, P.O. Box 3006, 7001 Trondheim, Norway.
Two late Precambrian sedimentary sequences beds (Holtedahl 1918, FØyn 1937, Banks et al. consisting of essentially unmetamorphosed sedi 1971, Siedlecka & Siedlecki 1971). A Rb/Sr mentary rocks and exhibiting lithostratigraphic whole rock isochron age (recalculated according similarities occur in west and east Finnmark to 87Rb A= 1.42.10-11 a-1) of 650± 7 Ma B. P. (Fig. I). Both sequences, the Porsangerfjord has been obtained on shales of the Nyborg Group in the west and the Tanafjord Group in Formation located between the Smalfjord the east, are predominantly terrigenous and both (Lower) Tillite and the Mortensnes (Upper) Til contain carbonate strata at the top. The Tana lite, thus confrrming the V endian age of the fjord Group is autochthonous while the Por glacigene deposits (Sturt et al. 1975). A Rb/Sr sangerfjord Group occurs in an allochthonous whole rock isochron on sediments of the under position and forms a nappe, the Gaissa Nappe, lying VadsØ Group has indicated an age (recalcu thrust over autochthonous Vendian and Lower lated according to 87Rb A= 1.42. w-u a-1) of Cambrian strata. This nappe is itself overlain by 805± 19 Ma B. P. (Sturt et al. 1975). Based on the metamorphic Laksefjord Nappe and the the above figures the Tanafjord Group is gene Kalak Nappe Complex (FØyn 1960, 1967, White rally considered to be Upper Ripheån and/or ·1968, Gayer & Roberts 1971, Siedlecka & Vendian. A study of acritarchs suggestsVendian Siedlecki 1971, Roberts J. D. 1974, Roberts D. age for the whole of the Tanafjord Group (G. 1974). Vidal, pers. comm. 1978). The Tanafjord Group constitutes part of the The Tanafjord and the Porsangerfjord Groups Late Precambrian to Tremadocian sedimentary have been considered lithostratigraphically equi sequence of east Finnmark, resting with an ero valent because of their lithologic similarity sional contact on the crystalline basement. Var (FØyn 1937, Williams 1976). Consequently, their ious formations of the Tanafjord Group (and uppermost carbonate formations, the Porsanger subjacent beds of the VadsØ Group) are overlain Dolomite (of the Porsangerfjord Group) and the by Varangian tillites (Lower V estertana Group) Grasdal Formation (of the Tanafjord Group),
with a slight angular unconformity _ The tillites have also been taken to be correlative. are thought to be of Vendian age and a pre-Ven The geology of the c. 250 m thick Porsanger dian age has been suggested for the subjacent Dolomite has been studied in some detail by
l -GeologiskTidsskr. 1/80 2 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980)
......
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +[ + + Late [::::::::3 Digermul Group (Cambro-Ordovician) Løkvikfjell Group Precambrian � & Groups Vestertana Dividal Laksefjord Group Undifferentiated � (Vendian-L.Cambrian)
c=J Tanafjord & Porsan- Precambrian basement · · · -gerfjord Groups Presumed f-;·::::.;:)1 Vadsø G roup Upper Kalak Nappe Complex Riphean- Thrusts llliiiii!Il B arents Sea Group l Vendian 100km
Fig. l. Simplified geological map of Finnmark; A: location of Fig. 2, B: location of Fig. 17 a.
White (1969) and J. D. Roberts (1974). Both columnar stromatolites of both these formations, authors introduced, independent!y, stratigraphic and with this objective in mind the writers spent subdivisions of the formation and confirmed the August 1975 studying stromatolite forms in the presence in its members of columnar stromato field and collecting specimens for laboratory lites discovered earlier by Holtedahl (1918). Re examination by J. Bertrand-Sarfati. The aim of cently, the formation has been studied by Tucker the present paper is to describe the stromatolite (1977). forms, to evaluate their stratigraphic im The Grasdal Formation contains an areally portance, and to discuss the problem of correla restricted dolomite about 100 m thick. This for tion between the Porsanger Dolomite and the mation has been briefly described by Siedlecka Grasdal Formation. & Siedlecki (1971), who also reported the pre The material described embraces 60 samples sence of columnar stromatolites in the dolomite. and the bulk of it was collected by J. Bertrand This observation stimulated interest for a Sarfati from the Porsanger Dolomite in 1975. systematic description and comparison of the Additional samples were collected by A. NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 3
Siedlecka from the Grasdal Formation and the Porsanger Dolomite in 1975 and 1976. One sam ple was provided by S. Siedlecki. The collection is housed in the Centre Geologique et Geophysique, U niversite des Sci ences, Montpellier, France.
Porsanger Dolomite The stratigraphic subdivision of this formation introduced in the western Porsangerfjorden hea by White (1969) proved to be extremely useful while collecting the stromatolites. The eight un its A-H are easy to recognize and three of them, � D g Porsanger Dolomite Older Formations of the Kalok Nappe B, F, and H, contain horizons of discrete colum Porsangerfjord Group nar stromatolites and interconnected domal Fig. 2. Location map in Porsangerfjorden (after White 1969 forms which were described briefly by White and Roberts 1974, simplified). (1969). The domal forms are also present in unit l. Akkanholmen; 2. Gåradak S; 3. Gåradak N; 4. Kolvik S; G. As pointed out by Tucker (1977), the litho 5. Trollholmsundet; 6. ReinØya; 7. Hestnes-Sinopivarre; 8. Pavuscokka. stratigraphy introduced by White (1969) is also applicable in the eastern Porsanger. Dolomite (Fig. 3). diameter and up to 23 cm in height (Fig. 4). Interspaces are fllled with dolarenite containing clasts of dolomicrite, algal-mat flakes, and occa Unit B sional ooids (White 1969). This is a 3 m-thick stromatolite 'reef consisting Along the coastal section of western Por of discrete columnar stromatolites, 2.5-15 m in sangerfjordenand on northern Akkanholmen the
White� 1969228m 0 H 0 0 ® ø G jl H =' micrite �H edgewise breccia VIl 210 G G - chert � � G � r----1 oncolites? VIl o •• sandstone VI G G 170
Ill Ill V ® a VIl VIl � il 13 11 , .. < D E c B r�;;� A c c B B A A A Fig. 3. Succession of the stromatolite horirons in the Porsanger Dolomite with reference to White's units A-H. Not to scale. For localities, see Fig. 2. 4 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) stromatolites form a horizon of bioherms which sion of composite laminae (definition of Monty have no precise boundaries and which are 1976:195). Each lamina is composed of a superposed one upon the other without any clear dolomicrosparitic basal layer followed by a relationship (Akkanholmen). InfiJ.ling consists of micritic dark top layer. Boundaries between the dolointramicrite. Unit B is composed entirely of two layers and between superposed sets of a new stromatolite form belonging to the group laminae are indistinct. Micritic layers often Line/la Kry lov 1967. coalesce and diverge. In the micrite, molds of fiJ.aments (clear short tubes) can be seen. Carbo nate and cherty spherulites are frequently 'ridd ling' the laminae. Discontinuous fenestrae paral Group Linella Krylov 1967 lel to laminae are fiJ.led with clear dolosparite. Type form.- Line lia ukka Krylov 1967: 37. Infilling. - This consists of micrite which is Diagnosis. - Bumpy subcylindrical or tuberous, difficult to distinguish from that of the micritic more or less parallel columns with parallel to mats. Small-scale debris of peeling mats is scat slightly divergent branching, frequent projec tered randomly in the micrite. tions, often pointed. Comparisons. - L. akaniella is comparable to Age.- In U.S.S.R. Vendian, Upper Riphean. Gymnosolen, Patomia, and f.,inella, and seems best assigned to Linella. Patomia Krylov is straighter and has smaller and more regular surface bumps, while Steinman is Linel/a akkaniella f. nov. Gymnasa/en smoother, less often ramified with divergent Fig.4 active ramification(after the definitionofRaaben Name. - From Akkanholmen, an island where: 1969) and has enveloping laminae forming a there are good outcrops (Fig. 2). continuous wall. L. akaniella differs from L. Holotype.- n69. ukka Krylov, which is more bulbous and con Material. - Twelve samples were collected stricted before branching and exhibits abundant from three localities: (l) a coastal section on the ribs and bridges. It also differs from L. simica western side of Porsangerfjorden, ca. 2 km SW Krylov, which is characterized by frequent reg of Gåradak; (2) ca. l km SW of Gåradak; and (3) ular ribs, and from L. avis Krylov (in Walter on the northern side of the island Akkanholmen 1972), which has a continuous true wall of (Figs. l, 2 and 3). Two specimens from coalescing laminae. It closely resembles L. Pavuscokka (east side of Porsangerfjorden) are munyallina Preiss, which has similar parallel straighter than those from the other localities branching and unwalled columns, but exhibits a and show different microstructures. It is there more regular diameter. fore uncertain whether or not they represent the same form. Unit F Description. - Columns are generally vertical or inclined to the bioherm edges. They are sub According to White's (1969) investigations this cylindrical to slightly turbinate with a lobate unit is 21 m thick and contains the most promi horizontal section (Fig. 4). The column diamet nent columnar stromatolites associated with ers vary from l to 6 cm (most of them are 2-3 domal forms and with undulating continuous cm). Surfaces are bumpy and tuberous, some algal laminated beds. White (1969) has disting times with l>eaks. Branching is frequent, parallel uished two distinctive horizons of columnar to slightly divergent, and sometimes columns stromatolites separated by an algal laminated have niches in which there are small pointed interval about 5 m thick. Tucker (1977) referred projections. Coalescence between adjacent col to Unit F as second biostrome and proposed a umns is frequent. The surfaces of column mar formal name, the Skjaanes Member. gins are either ragged or marked by a thick Stromatolite horizons of Unit F crop out on non-laminated wall which shows no clear rela both sides of Porsangerfjorden. Unit F appears tionships with the laminae. The synoptic profiJ.e to be most complete in the coastal section south is variable; it tends to be highly convex where of Trollholmsundet (Figs. l, 2 and 3) where six the wall is developed but the laminae are only distinctive horizons of columnar stromatolites slightly convex. have been recognized (Figs. 3 and 5) as well as a Microstructure. - This is a repetitive succes- (seventh) horizon of huge domes at the top. NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 5 ,--- / l- - b - Fig. 4. Line/la akkaniella f.nov. a: bioherms of Line/la(Gåradak S, drawing from field photograph. Scale bar: 7 cm). b, c, d: reconstructions of såmples: A69 from Akkanholmen; n9 and n3from Gåradak N, respectively. Scale bars: l cm. e: straight columns from east Porsangerfjorden (Pavuscokka n37). Scalebar: l cm. Horizon I. - Large oncolites and short eroded Horizon Ill.- Columns having a well-defined straight columns embedded in a channel-fill de conical axial zone in the central portion which is posit about 0.5 m thick. This grades upward in to: encircled by branches arranged in a verticillate Horizon Il. - Straight subparallel columns manner. changing rapidly into turbinate and frequently Horizon IV.- Large straight columns passing ramified columns. There is a continuous tran to a flat to undulate laminated bed. sition to: Horizon V. -A conspicuous yellow-coloured 6 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) Trollholmsundet VIl ,! _, calcarenite VI -Y--T- micrite ... � chert ...... sandstone V Gåradak N Reinoya -- VIl IV � �� Gl��''- �(©' _, :-:·�.::!.:!. ,. . m •:.·.·.·.·.· ·.·.·� 5 - �· ·�·\.N � ".-':\, Ill ..,�., ccc 0, ftt�ul Ill 4m- � 6��p, )1 � 3m- p�� � ø --- �., '.39� lf�f(l�� 11 li Fig. 5. Stromatolite sequence in -���)J � P- ?l f'l � 2m- VJ �� �l\ \i.wll White's Unit F. Schematic sec- · ,. -p; t::»o tion from three localities: 1m-13 1l � ,...��- � Trollholmsundet, Gåradak N ,.� ... '· ..·' :.• ..· ,1.:. and ReinØya. stromatolite biostrome overlying a layer of Horizon VII. - Huge domes in a biostrome calcarenite flakestone. It consists of bulbous, composed of continuous laminae with complex highly ramified short columns. convolutions and high relief. The horizons IV, Horizon VI. Two superposed domed V, and VI are lacking in the other examined biostromes consisting of large bioherms (from 30 sections. cm to 1.2 m) of more or less large columns. Fig. 6. a, b: Onkolites and nodular stromatolites associated with small columnar forms occurring in a channel. Drawings from field photographs. a. East Porsangerfjorden near Hestnes. Scale bar: l O cm. b. Gåradak N. Scale bar: l cm. c-h: Eleonora laponica f.nov. c: short, oblique columns at the base of the bioherms. Eleonora occurs at the top of the reconstruction (sample n22 Gåradak N); d: small globular column at the base of the bioherm (sample N30 Gåradak N); e: holotype ofE. laponica from Gåradak (sample n4); f: sample collected by Siedlecka in 1973 from Hestnes, east Porsangerfjorden; g: horizontal section, drawing from field photograph, Trollholmsundet. Scale bar: 5 cm; h: base of bioherm showing rapid column enlargement (sample n31, Gåradak N). Scale bar for g: 5 cm, all other scale bars: l cm. Columnar s tromatolites from F"m nmark 7 8 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) Fig. 7. Eleonora /aponica f.nov. Drawings fromfield photo grapbs; a: Hestnes, east Porsan gerfjorden; b: Trollholmsundet. Scale bars: 3 cm. Horizon l nate breccias and erosively-based calcarenites, and oncolites are accumulated in these channel deposits. They areellipsoidal and measure about Oncolites and small columns 10-30 cm (or more) along their longest axis. The (Fig. 6a, b, Fig. 9d) asymmetrical development of laminae around Material. - Three samples were collected from most of the oncolites shows that there was little different localities. rotation during lamina accumulation: The Made of occurrence and description. - This growth of these oncolites was predominantly horizon occurs over the entire Porsangerfjorden lateral or sub-lateral with initial columnar area. The base of the unit is underlain by carbo- growth. NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 9 Microstructure. - This is of the alternating type and is constructed of three different, simple or composite mats. The first type consists of dolomicrospar with or without detrital particles (less than silt-size); the second is micritic with carbonate spherulites; and the third is a kind of thin micritic film exhibiting a network-like fabric parallel to the lamina surfaces and clearly visible in a tangential cut. Horizon Il Group Eleonora Bertrand-Sarfati 1976 Type form. -Eleonora ramosa, Bertrand-Sarfati & Caby 1976:22, fig. 13. Diagnosis. - Turbinate columns either vertical or oblique with many small ramifications around a central column. The branching is mar kedly divergent. Age. - Presumed to be V endian (Bertrand Sarfati & Caby 1976): Eleonora laponica f. nov. (Fig. 6c-h; Fig. 7a-b; Fig. 8; Fig. 15b) Holotype.- N 4. Name.- From 'Lapon', the French name for the native people of northern Scandinavia. Material. - Ten samples from east and west Porsangerfjorden. Made of occurrence. - Straight ramified col umns usually vertical but sometimes inclined. Near the base, above the oncolites ofHorizon l, some columns are nearly horizontal; these have probably fallen over from their vertical position. Description. - Short and globulous columns vertical to slightly oblique when ramifying. They are turbinate with lobate horizontal section, and the diameter varies greatly with sudden enlarge ments up to 10-12 cm just below ramifications. Fig. 8. Eleonora laponica f.nov. The branching is frequent and markedly di Fragment of a bioherm showing growth of E. /aponica, vergent; the new branches start growing hori Trollholmsundet. Drawing from field photograph. Scale bar: 7 cm. zontally before hending upwards to an erect position. The branches often thin upwards while the main column continues to enlarge forming folds resulting from irregular superposition and niches. Ramification is verticillate with 3-5 curling of leathery mats prior to lithification. branches around a central column. External Microstructure. - There is an alternation of surfaces of the branches are smooth and have a two different kinds of laminae: (l) dark thick wall of enveloping laminae. The laminae dolomicrosparitic followed by (2) anastomosing are convex with abundant disconformities and thin micritic fllms forming laminae of equal 10 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 11 thickness all over the surface of growth. In the around a central column exhibiting a conical overlapping portions of columns, the first type is central zone. This form may be included in a disrupted in juxtaposed cushions (a diagenetic cylinder. It is never associated with unramified and/or primary feature?). columns of Conophyton. Between the laminae there are flat sheet cracks ftlled with dolosparite. - Dolomicrite containing silt-sized Infilling. Gaaradakia jacutophytonica f.nov. fragments of peeling mats. (Fig. 9a, b, c, e; Fig. lOa-c; Fig. l I) Comparisons. - This form shows the general characteristics of the Tungussid supergroup. De Holotypf!. - N 18. tailed comparisons may be made with Inzeria Name. '..:..Fromlacutophyton which it resembles. groenlandica Bertrand-Sarfati, Baicalia bul6osa Material. Eight samples from various Bertrand-Sarfati, Tungussia wilkatanna Preiss, localities in east and west Porsangerfjorden. and Eleonora ramosa Bertrand-Sarfati. The Mode of occurrence. - This form arises di similarity to /. groenlandica is, however, re rectly from Eleonora laponica by exhibiting in stricted to the vertical sections visible in the creasingly convex laminae and then a true outcrop. Reconstructions of the considered form central zone. Bushes of ramified closely spaced show bushy ramification with pinching at the columns of Gaaradakia jacutophytonica form a base, absent in /. groenlandica. The bumpy conspicuous biostrome which is ubiquitous in surface, multiple ramification, and the presence the Porsanger Dolomite. of a smooth surface and of a wall make the dis Description. - This form consists of two distinct cussed form similar to T. wilkatanna; it differs, parts; the main column and the petal-like however, from the latter by the absence of lat branches. The main column is straight, vertical erally linked portions of columns. It differs from and with variations of diameter from 3 to 7 cm. B. bulbosa in the lack of multiple ramified Laminae are conical, inclined at ;:;. 40°, but never branches running around a globulous main col vertical. There is a central zone as in Conophy umn, in the rugged laminae margins and in the ton. This shows a distinct thickening of laminae microstructure. Eleonora fits well with the re and is not straight as in C. miloradovici and C. construction but the central column of E. ressoti but exhibits changes in the orientation of ramosa does not enlarge after ramification. In the axis. At the edges of columns the laminae addition, the microstructure of E. ramosa is exhibit interruptions which mark the beginning characterized by thin mats with no regular of branching. The branches are petal-like and in superposition of homogenous micritic mats and horizontal section appear like ribs superimposed by the absence of a distinct wall. on the circular section of the main column. Laminae of the branches are parallel to the peripheral laminae of the main column when the Horizon Ill branches grow vertically, and become increas ingly convex upwards. Ramification is markedly Group Gaaradakia gr. nov. divergent; the branches, obliquely oriented in Type form: - Gaaradakia jacutophytonica f. nov. the early stage of growth, reorient usually to a Name. - From the form type locality Gåradak. vertical position and prevent the growth of the Diagnosis. - Bushes of petal-like ramifications neighbouring columns because of the tight spac ing. Maximum relief is about 30 cm. The surface of the 'petals' is ragged without any kind of wall Fig. 9. Gaaradakiajacutophytonica f.nov. or enveloping laminae. a and b: horizontal section, (Gåradak N); a. general view, · hammer head: 18 cm; b: Scale bar: lO cm; c: vertical section of Microstructure. - There is a difference in the the central axial zone; notice thickening of laminae (nl7, microstructures of the two portions. The central Gåradak N; scale bar: 2,5 mm); e: curling of mats on a slope column shows an alternating succession of dark (nl4, Gåradak N, scale bar: 6 mm); c and e: negative prints of thin sections. thick micritic laminae and clear microsparitic Eleonora laponica laminae (like E. laponica except for the ftlms). d: base of bioherm, overlapping of laminae (N30, Gåradak N, Laminae are arranged in macrolaminae resulting negative print of thin section), scale bar: 6 mm. from the predominance of either microsparitic or Line/la tro/lina f: bushes of vertical or slightly oblique columns (Trollholm micritic laminae. Branches exhibit a banded sundet). Hammer head: 18 cm. microstructure of clear dolosparitic and dark 12 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) Fig. 10. Gaaradakiajacuto phytonica gr.nov., f.nov. a: base ofGaaradakia, oblique section: central part at the base, peripheralbranches at the top and to the right. Gåradak N; b: V ertical section of Gaaradakia showing changes of orientation of the axial conical zone during growth. Central col umn has a very variable size. Trollholmsundet; c: horizontal section (see Fig. 9 b); small central circular zone and large verticillate petal-like branches, inscribed in a circle. Gåradak N. Drawings from field photographs. All scale bars: 2 cm. microsparitic laminae without precise limits, and Georginia Walter. However, in contrast to with no macrolaminae developed. Recrystalliza Gaaradakia, Georginia possesses small con tion is more advanced in the branches than in the torted projections on branches and is associated central column. with isolated, cylindrical, non-ramified columns Infilling. -This is restricted to the deep depres of Conophyton (M. R. Walter, pers. comm. sions between branches. At the base a few 1977). There is also an obvious similarity be silt-sized carbonate grains are embedded in a tween the described form and Jacutophyton dolosparite, and this is followed by a micrite. Schapovalova. However, there is no clear de This is darker than the stromatolitic micritic finition of the latter available, and therefore mats and contains interwinned tubes, probably revision of the Jacutophyton is urgently needed. molds of fllaments. Similar micrite with flla Non-ramified columns or large portions of col ments occurs in patches in the infilling of Line/la umns with a high relief and a clearly defined akkaniella. central zone are generally accepted as typical of Comparisons. -The described form is similar to Conophyton and branches of Jacutophyton de- NORSK GEOL OGISK TIDSSKRI-FT l (1980) Columnar stromatolz'tesfirom znnmark g 13 · Fi l. g. l Gaaragr. nov.,daktajacuto- f.nov. phytonicaReconstruct' n, Gtu:adak N (holotype nl� Honzon Ill of Unit F. Sea! e )b. ar: cm. l . . . velop upon these co mcal column As observed with th'm layers of spante contai m small detri . · by Bertrand-Sarfati (1972) in the ;a hara, branch tal grains . B oundaries between t� e layers are ing always results in a flatteni� g of the central indistinct. Conophyto� colu n. In the e le from the � :: Porsanger te thece ;, nei ny flatten- ��m< � ing which co be related to b ranchmg n�r are discrete columns o f Conophyton fou nd m the . h a d�acent beds . In the described f;or m t ere is only one type of morphology p re sent from the bottom to the top of the growth··a con·>ea central . . 1 column an d the vert>eillate petal-lik� branches. Thecefore the new name Gaarada k za has been mtroduced. IV Horizon Large Stratght · Columns (Fig. t2) Material. - N29. Mode of occurrence . � A biostro:, e ompoa Microstruc�ure. - Thick m t consisting � � mainly of h omogenous dark micnte either di- rectly su perposed on each other or intercalated . 14 J. Bertrand-S arfatl & A . Siedlecka NORSKGEOLOGISK TIDSSKRIFT l (1980) e . Fig. 13. f . nov a·· UpperU part ne Ilaof trollma Horizon T ollholmsund e t (sample n28)· b: Middle part of Horizon (samp e c: holotyp� . ' . . collected by S1edl ec ka in 1973)�, d· . tlattened upper P arts of columns· eroded block (sample n26),1 e. n27). horlzontal sectlon'�""''"', sa mple F . V ' V 12. All scale bars. 1 cm. , NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 15 Fig. 14. f. nov. a: basal Line/lalayer of tro/linaHorizon scale bar: cm; b: middle ofHorizonV, (see 5Fig . 91), scale bar: 10 cmV. Drawings from field photo graphs, Trollholmsundet. umns are similar, exhibiting a more or less Horizon V globular shape and containing a variable amount of clayey material. They either grow directly on Group Line/la Krylov 1967 the calcarenite su rface or develop fromflat-lying Line/la trollina f. nov. laminae. Small channels (up to 0.4 m deep) filled with breccia locally cu t the basal stromatolite (Fig. 13a-e; Fig. 14a-b; Fig. 9; Fig. 15a) layer. _ Holotype. -Fl 2. Description. -Predominantly erect columns, in Material. - Seven samples from the same area places slightly oblique. The horizontal section is in west Porsangerfjorden. lobate. The columns are not closely spaced; they Name. -From Trollholmsundet where this layer frequently ramify and some enlargeafter ramify is well developed. ing while others cease to grow. Smooth bumps of occurrence. - Upon the calcarenites occur on the su rface. Ramification is parallel to Made which overlie Horizon IV (see above) there is a slightly divergent. Occasionally bridges of flat yellow biostrome of frequently ramified colum laminae overlie two adjacent columns which nar stromatolites forming three Jayers. All co!- become globular. Relief varies in height from O 16 J. Bertrand-Sarfati & Siedlecka NORSK GEOLOGISK TIDSSKRIFT (1980) A. l NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 17 to 4 cm. Laminae envelop the margins of col shape of laminae. However, there is a pro umns and are clearly defined within the thin nounced difference in the microstructures of L. wall. Surfaces of the laminae are smooth and trollina and L. ukka; the latter exhibits interlami the y show a pronounced asymmetry; on one side nar chains of pellets and indistinct boundaries of the column the laminae are flat while on the between laminae. other they are steeply inclined, with maximum convexity near the edge. Laminae show distinct Horizon VI (?seasonal) changes, disconformities, and trun cations, but are less folded than in Eleonora Domed biostromes laponica. Microstructure. - This is a repetitive compo Material. - One sample from the lower and site lamination. The clear dolosparite basal three samples from the upper biostrome. lamina grades upwards in to a dark micritic layer. Made of occurrence. - Two superposed This layer is either continuous and with equal domed biostromes, 4-4. 5 m thick consisting of thickness or, more commonly, disrupted into 0. 3-1.2 m large juxtaposed bioherms. An ero juxtaposed 'cushions'. No macrolaminae are sional surface separates the two biostromes. present and the micritic laminae are predomi Description of the lower biostrome. - Im nant. mediately upon the flat-lying laminae terminat lnfilling. - This consists of micritic carbonate, ing Horizon V there are ca. 0.3 m-thick domed comprising small grains at the base of each cyclic bioherms separated by minor channels ftlled layer and grading upwards into clear with muddy carbonate containing flake-shaped dolomicrosparite. clasts. The bioherms consist of small ramified Comparisons. - Erect turbinate columns with no columns. The size of the bioherms increases horizontal branches are similar both to Baicalia upwards and large bulbous or nodular columns Kry lov and to lnzeria Krylov. Linella trollina appear. These coalesce near the bioherm edges has a smooth surface and a discontinuous wall into a crust separating two adjacent bioherms. analogous to that of lnzeria but, unlike it, has no At the top of the biostrome there are nodular niches and exhibits asymmetric laminations. The isolated stromatolites similar to those of some microstructure of L. trollina resembles that of l. horizons in the Eleonore Bay Group on Green groenlandica Bertrand-Sarfati. The discussed land (Bertrand-Sarfati & Caby 1976, fig. 4, top of form differs from Baicalia capricornia - a form the basal left section). exhibiting characteristics of both the lnzeria and Microstructure. - The small columns at the the Baicalia groups - in having a less regularly base (N72, Fig. 15a) are composed of micritic banded lamination. mats with ftlamentous tubes very similar to Similarities with Linella ukka are most strik Linella trollina. The larger columns exhibit a ing, in particular in the tuberous shape of the microstructure similar to that of the upper columns, structure of the wall, and asymmetric biostrome (see below). Description of the upper biostrome. - At the base the upper biostrome contains small Fig. 15. UneUa tro/lina f.nov. bioherms of radiating walled columns. The se are a: columns showing lamination truncated hy enveloping laminae.Trollholmsundet, Fl2, sample collected by Siedlecka overlain by flat-laminated domes passing upward in 1973; scale bar: 3 mm. into large straight unramified columns or Eleonora laponica f.nov. pseudocolumns with unwalled surfaces. Small b: negative print of thin section showing a thick wall and channels containing flakes occur between the folding of mats. Hestnes, sample FlO collected by Siedlecka in 1973; scale bar: 3.5 mm. columns. lnzeria sinopivarra f.nov. Microstructure. - This is characterized by an c: part of the wall consisting of thick complex micritic laminae alternation of composite laminae arranged into (sample n34, east Porsangerfjorden on the coast), scale bar: 3 macrolaminae. Macrolaminae vary considerably mm. (I) Minjaria tana f.nov. but two principal types may be differentiated: d: enveloping laminae, variable thickness (sample Gr 13 a type dominated by micritic films with subordi Grasdal, collected by Siedlecki in 1971), scale bar: 2 mm. nate thick dolomicrosparitic laminae. Laminar e: unnamed stromatolite from Grasdal, Horizon I; very small sheet-cracks occur between the laminae; (2) a columns in a sandstone (sample 6 b Grasdal, collected by 3 Siedlecka in 1973). Scale bar: 1.1 cm. type dominated by up to mm-thick micritic All are negative prints from thin sections. laminae containing molds of ftlaments and grad- 2 -GeologiskTidsskr. 1/80 18 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT (1980) l ing downwards into su bordinate dolomicrospari below derive from the 'third' and 'fourth' tic laminae. U pper su rfaces of the micritic biostromes of Tu cker (1977). laminae are sharp. Desiccation cracks are visible Mode of occurrence. - Straight columns in a in these macrolaminae. 1.5 to 2 m thick biostrome. The columns grow on oncolitic calcarenite. The dimensions of the col Horizon VII umns increase upwards. The oncolites are su b spherical, about 5-6 mm across. The largest Huge domes examples have a core of diagenetic chalcedony in which remnants of an oolitic texture are Material. - Three samples from coastal sec clearly visible. Around this core there is an tions in east and west Porsangerfjorden. irregular fringe of rhombohedral crystals of Description. - The domes consist of massive secondary origin. This is followed by an ou ter algal constructions up to 7 metres high, com microspantic and pyrite-rich envelope which ex posed of horizontal to vertical often convolute hibits a bumpy su rface similar to that of the and recumbent discontinuous laminae with a Saharian 'crenulata' (Bertrand-Sarfati 1972). predominance of vertical and inverted layers. The uneven su rface may be the result of growth The relief of the laminae is around 20 to 50 cm. of filamentous algae on the oolite su rfaces. The Microstructure. - There is no regular lamina tu fts are either discrete or coalesce forming a superposition. The domes consist largely of continuous lamina. macrolaminae composed of several thin micritic laminae. The macrolaminae are discontinuous, separated by lenses of detrital carbonate and Group Inzeria Kry lov 1963 voids filled with dolosparite. The sets of Iaminae (Fig. 15c, Fig. 16a-c) often thicken laterally, separate and then merge together, and some become folded. This is typi Type form. - Inzeria tjomusi Krylov 1963:72. cal of an independent growth of Iaminae and Diagnosis. - Stromatolite with su bparalle1, su b macrolaminae and at variable growth rates. The cylindrical, usually ribbed columns. Ramifica resulting lenticular fabric is unknow n in other tion is parallel to slightly divergent and occurs in types of stromatolites. niches. Column su rfaces are either lacking walls or are walled. Age. - (?) Unit H U pper Riphean and V endian. According to White (1969) this unit consists of dolomicrites at the base and of calcarenites and Inzeria sinopivarra f.nov. edgewise conglomerates higher up. These are followed by a stromatolite horizon which is Holotype. - N34. poorly exposed in west Porsangerfjorden. In east Name. -From 'Sinopivarre', a hill on the east Porsangerfjorden the unit occurs about 30 m side of Porsangerfjorden (Fig. 3), the western above the large algal mounds (H orizon VII) slope of which constitutes the holotype locality. marking the top of Unit F. It has also been ·Material. - Four samples from east Porsanger recognized on the island ReinØya in a stratigrap fjorden and Reinøya. hic position some (?) 20 m above the algal Description. - Vertical to slightly oblique col mounds and qu artz sands which are present in umns, su bcylindrical to slightly tu rbinate after the uppermost portion of Unit F, and beneath ramifying. The diameter is variable with a gene dolomicrites constituting the typical lithology of ral increase in size from the base of the the base of Unit H. The northernmost ou tcrop of biostrome to the top (from 2-3 cm to 7-8 cm). this horizon occurs south of Kolvik where it also The horizontal section is ellipsoidal. Ramifica appears upon the algal domes and qu artz sands tion is slightly divergent. U su ally some of the of Unit F. The stratigraphic distance of this , columns enlarge above the branching point and horizon from the top of UnitF, i.e. the thickness overlap others preserved in niches. Column of Unit G, seems to vary considerably, bu t the su rfaces are smooth and bumpy with some small structure and composition of the biostromes are projections. A thick wall envelops the column very much the same throughout the area. It is su rface. Highly convex laminae are cu rled and not unlikely that the stromatolites described show disconformities. NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 19 Fig. 16. Inzeria sinopivarra f.nov. a: drawing from field photo graph; partial erosion of col umns, Unit H in east Porsanger fjorden. Scale bar: 3 cm. b: large columns, Unit H, coastal section in east Porsangerfjorden (sample n34). c: small columns, Unit H, on ReinØya, sample n65. b, c scale bars: l cm. Microstructure. - This consists of a repetitive and the straight attitude with parallel branching composite lamination. The relatively thick indi argue for /nzeria. Our form differs from/. multi vidual laminae are clear near the base. Higher up p/ex Preiss, /. tjomus i Kry lov, and ev en from the y consist of micrite with dolosparitic patches I. intia Walter and /. toctoguli Krylov (which and grains, quartz silt, ooids, and fine debris of both have walls) in having no ribs. The micritic mats. The laminae have probably re miCrostructure, the shape of the columns, and sulted from the growth of spaced bushes of erect the decrease of size before ramification are all fllaments. Interspaces between these bushes similar to Line l/a ukka (Kry lov 1967, pl. VI) but have been fllled either by debris, by in situ the latter form lacks niches. /. confragosa developed algal lumps (Monty 1976, fig. 18), or Semikhatov has few ribs and niches but has by sparite. more divergent ramification than our form. Infilling. - Poorly sorted, rounded detrital Some anastomosed micritic 'fllaments' like particles associated with ooids and larger frag those in our form are present in/. ny-frislandica ments of peeling mats. Raaben; however, these have a more regularly Comparisons. - Similarities to Inzeria Krylov banded microstructure. Apart from the patchy and to Baicalia Krylov are obvious and the wall, /. sinopivarra resembles/. djejimi in having presence of niches, walled marginal surfaces, the same kind of small projections and sudden 20 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) Ø Vestertono Group � Tillites I�I Grasdal Farmation gj[.l Older Formations of the Tana fjord Group l;SLJ 2km scree �Minjaria Dolomicrite & �-= llakestone interbeds �l brecc ia Ed� �\af:. :e Fig. 17. a: Location map of Grasdal area (after Siedlecka Fig. 18. Grasdal Formation. Small bushy columns of the first Siedlecki 1971, simplified). & horizon. Infilling is silty sandstone. Both the stromatolites and b: Schematic section of the Grasdal Formation dolomites from the flat floors are carbonates. Samples Gr 8b collected by ioner Grasdalen showing the distribution of the three Siedlecka in 1973. Scale bar: 3 mm. stromatolite horizons. enlargement of the columns. Our form is also vered with scree but there are three distinctive in comparable to groenlandica Bertrand-Sarfati situ stromatolite horizons (Fig. 17). which has a continuousI. wall and few ribs, but the sinopivarra sudden enlargement of columns of Horizon I after ramification and the microstructureI. consti (Fig. 18, Fig. l5e) tute the main differences. In addition, both forms differ considerably in size. This horizon is located about 10 m above the terrigenous beds marking a transitional zone from the lower to upper member of the forma Gras dal For mation tion. The stromatolite horizon is 1.8 m thick and consists entirely of bushy bioherms of irregularly The middle portion of this formation consists of radiating tiny columns. Six samples were col dolomite while terrigenous strata occur mainly in lected from this horizon. No name is introduced the lower and upper parts of the formation. The for this form because the collected material is Grasdal Formation has recently been redefined insufficient for a final diagnosis and because it and subdivided into two informal members. The shows equally important similarities to several stromatolite-bearing dolomite has been assigned other forms. - to the lower part of the upper member. The total Description. - Small columns, vertical or obli thickness of the redefinedGrasdal Formation is que, sometimes inverted but never horizontal. ca. 280 m (S. Siedlecki, written comm. 1978). They are subcylindrical with constrictions of The thickness of the dolomite is in excess of 100 diameter, which varies from 0.7 to l cm. Ramifi m according to S. Siedlecki, (pers. comm. 1978); cation is parallel to slightly divergent without however, it is nowhere continuously exposed. changes in diameter either before or after Large portions of the dolomite section in inner ramifying. Column margins are smooth, but Grasdalen examined by A. Siedlecka are co- laminae either terminate sharply at the column NORSK GEOLOGISK TIDSSKRIFT (1980) Columnar stromatolites from Finnmark 21 l surfaces or the columns are enveloped by a wall Minjaria Krylov 1963 showing a different structure. Convexity is usu ally high but can be as low as zero. Few bridges Type form. - Minjaria uralica Krylov 1963: 76- are present and there are also intercolumnar 81. discontinuous floors, some 5 cm vertically Diagnosis. -Stromatolites with even, subparal spaced, on which micritic algal mats grow di lel, subcylindrical columns. Ramification is in rectly upon the loose sand. frequent and generally parallel. The surface is Microstructure. - This is a composite repeti covered by a multilamellate wall. tive lamination. Each lamina is composed of a Age. -Lower Riphean (Australia), Upper Rip homogeneous micritic upper part, either of equal hean. thickness or forming juxtaposed cushions, and of a microsparitic lenticular basal part. V ariations in the lamination fabric are independent of the Minjaria tana f.nov. environment. (Fig. 19, Fig. 15d) lnfilling. - There is a distinct upward change in composition of the inf"illing, reflecting changes of Holotype. -G .S. 1970. the sedimentary environment. Fairly large plates Material. - Two samples from the same loc of micrite occur at the base (detached fragments ality. of algal mats) and are overlain by intrasparite Name. -After the locality on the eastern side of containing quartz grains exhibiting an upward Tanafjorden(Fig. 17). increase in degree of roundness. Quartz sand Description. - Subparallel subcylindrical col stone with little carbonate cement and small umns varying in diameter from 2.5 to 5--6 cm. No fragments of micritic laminae forms the upper ramification is visible either in the outcrop or in part of the biostrome·imllling. the two examined samples. Column surfaces · Comparison. - Bushy bioherms of small-size show no bridges or peaks; smooth depressions columns are very similar to those of Parmites and bumps with low relief are the only surface concrescens Raaben (Bertrand-Sarfati 1972), but features. A thick multilamellate wall outlines the the latter show quite flat laminae continuous surface. Laminae have relatively high relief and from one column to the other and exhibit a fllmy abundant unconformities. microstructure. Individual columns of Vetella Microstructure. - This is a composite repeti ushbasica Krylov are comparable to our form, tive lamination, not really different from the especially in the rapid changes in diameter lamination of the frrst horizon stromatolites. (Krylov 1967: 58, fig. 31 ). However, Vetella is Each lamina has a microsparitic basal part with essentially a pseudocolumnar form because of rare silt-sized debris, and a dark micritic upper the continuity of the evenly banded laminae from part of varying thickness and often showing a one column to the next. Jurusania minuta discontinuous succession of cushion-like Bertrand-Sarfati has sl ightly larger col umns, oc patches of micrite. This fabric suggests that curs in isolated bioherms and exhibits a com bushy fllaments are responsible for the Iamina pletely different tussocky microstructure. formation. Infilling. - This consists of muddy carbonate Horizon 2 containing small particles of micrite showing the same ragged surfaces as the stromatolite This horizon is situated approximately 5 m laminae. stratigraphically above the frrst horizon. It over Comparison. - Within the Gymnosolenid family ties an erosional surface of interbedded characterized by straight, parallel, ramified dolomicrite, intrasparite-flakestone, and flat forms, only Minjaria Krylov shows an absence pebble breccia which exhibits imbrication of or scarcity of ramification and a well outlined pebbles and bimodal cross-bedding indicative of wall. Jurusania Krylov is also straight and sub tidal current activity. cylindrical but its laminae typically exhibit a Mode of occurrence. - Straight unramified different pattern of ragged surfaces. Minjaria columns in a 0.25 m thick biostrome the ex tent of tana differs from pontifera Walter by the which is uncertain. absence of bridges M.and peaks and it has a totally different kind of microstructure from that of M. uralica Kry lov. 22 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT (1980) l f.nov. Fig. 19. . Large straightMinjaria columns, tana no visible ramifications. Sudden enlargement of the columns (central part of reconstruct10n). Sample Gr 13 collected by Siedlecki in 1971. Scale bar: cm. l Horizon 3 basis of the stratigraphic distribution of stromatolite groups described here and taking About 15 m stratigraphically above the second into account the simil arities to other forms of the stromatol ite horizon there is a stromatol ite bed same group, certain observations may be made about 20 cm thick consisting of short sol itary as follows: col umns and cabbage-sized domal forms. This Linella akkaniella. The Linella group (known horizon is developed upon a carbonate in Russia and Australia) is primarily Vendian, cemented quartz sandstone containing abundant but it is al so known in the U pper Riphean. Our micritic lithocl asts and imbricated flat pebbles. form is related to Linella munyallina Preiss, B imodal cross-bedding of the sandstone testifies which is presumed to be either Late Riphean or to activity of tidal currents during the accumula Vendian. The other form, L. tro/lina, is related tion of the sand. to L. ukka occurring in the Vendian in USSR but The stromatolites of the third horizon consist known from the U pper Riphean in Australia. of macrolaminae exhibiting an internat pattern Eleonora laponica. Eleonora (know n in Eleo analogous to that of the domal stromatolites nore Bay Group of East Greenland) is Vendian present in the upper part of Unit F in the (late Late Riphean according to Vidal 1976). The Porsanger Dolomite. Rounded quartz grains oc microstructures of both Eleonora ramosa andE. cur in interlaminar pockets. laponica are very similar. Gaaradakia jacutophytonica. The new group Gaaradakia has been created because of the Stratigraphic significance of the absence of the Conophyton single isolated col Jacutophyton stromatolite assemblage umns usually associated with Schapovalova (LoweF, Middle, and Upper Rip The described stromatolite assemblage consists hean and Vendian). G. jacutophytonica shows of five new forms and one new group. On the some similarities to Georginia Walter (Vendian NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolites from Finnmark 2.3 to Lower Cambrian) but this form also displays Conophyton- like columns. Inzeria sinopivarra. The group Inzeria is known from the U pper Riphean in USSR, Au stralia, Spitsbergen, Greenland, and Northem Africa. The morphology of l. sinopivarra is related to that of l. groenlandica (East Green land). Its microstructure is very similar to that of I. ny-frieslandica, which is present in the upper part of the Middle Hecla Hoek Series of Spits bergen (just beneath the Vendian). Minjaria tana. The group Minjaria is Ubper Riphean (USSR, Australia). M. tana exhibits no dose affinities with other forms. The above comparisons show that, at the group leve!, the assemblage is characteristic of Vendian and Upper Riphean age. The identified stromatolites belong to stratigraphically im portant taxa (Preiss 1976) with the exception of the new group Gaaradakia and of Eleonora, which is also a relatively new group and there fore of an as yet unknown stratigraphic signifi cance. Correlation on a form leve!, crucial for stratigraphic conclusions (Preiss & Walter 1975) cannot be carried out; however, it is worthwhile to note that the described new forms are mainly allied to V endian/Late U pper Riphean forms and, to a lesser extent, to older forms. Fig. 20. a and b: Dolomicrite with fragments of (7) shells. Grasdal Formation. Scale bar: 0.2 mm. Stratigraphic correlation between the Porsanger Dolomite and Gras dal F ormation stromatolites constitute a reliable tool in stratigraphic work as has been postulated by The overall lithologic similarity between the many investigators of these organosedimentary dolomites from the Porsangerfjorden area and structures. fromGrasdalen, Tanafjorden, is striking and was 2) The Porsanger Dolomite and Grasdal For first pointed out by Holtedahl (1918). Later, this mation are time-equivalent portions of one car similarity combined with the analogous bonate province and the totally different compo stratigraphic position of the formations - both sition of their respective stromatolite assem occuring in the upper parts of lithologically com blages reflects environmental differences, not parable terrigenous sequences - was a key factor stratigraphic. in their lithostratigraphic correlation (FØyn 1937 Although neither of these explanations can be and others). This study has clearly shown that really proven there are some indications sup there are no comparable stromatolite forms in porting the first alternative and suggestive of a these two lithostratigraphically equivalent for possibly younger age for the Grasdal Formation. mations. In the poorly washed, bioturbated dolointraspa There are two alternative explanations of this rite underlying the Minjaria tana horizon of the situation: Grasdal Formation, some unusual fragments l) The Porsanger Dolomite and Grasdal For were discovered. The fragments are either mation, though lithostratigraphically correlative, straight or curved, some exhibit angular zig are not exactly time-equivalent. This explana zag outlines, as if crushed by compaction, and tion is based on the assumption that columnar occasionally a 'shepherds crook'-like shape_ 24 J. Bertrand-Sarfati Siedlecka NORSK GEOLOGISK TIDSSKRIFT (1980) & A. l may be observed (Fig. 20 b). The fragments are and on the Kanin Peninsula (G olovanov flat-lying in a dolomicrite matrix. The length Raaben 1967). It has also been shown that forms& of these elements is about 0.2�.5 mm, the thick of Boxonia and Line/la groups are typical of ness is in the range of 50 microns, and they Vendian stromatolite assemblages (Semikhatov consist of a fme-crystalline dolomite mosaic 1976). On the other hand, range zones of the (Fig. 20). The crystalline texture of these frag various Riphean taxa have been outlined and it ments makes them incomparable to algal-mat appears that lnzeria, Minjaria, Katavia, and flakes. The fragments are, in fact, most reminis perhaps Gymnosolen are confined to the Late cent of shell debris. If this interpretation is cor Riphean, while Boxonia, Jurusania, and Line/la rect, it testifies to the existence of true shelly exhibit a Late Riphean to Vendian age range; in animals at the time of deposition of carbonates addition, the forms L. ukka andL. simica appear of the Grasdal Formation, animals quite different to be restricted to the Vendian (Krylov 1967, from the non-skeletal Precambrian Ediacran Semikhatov 1976). faunas. On the other hand, no shelly bioclastic In the Arctic outside the Russian territories, material has even been reported from the Por the Upper Riphean stromatolite assemblage has sanger Dolomite, even though much more work been identified on Spitsbergen in the Hunnberg has been done there than on the Grasdal Forma Formation of the upper Middle Hecla Hoek (the tion. Roaldtoppen Group) of Nordaustlandet The IUG S Precambrian/Cambrian Boundary (G olovanov Raaben 1967) and in the conference (Siberia 1973) and the Cowie Akademikerbreen& Group (upper portion of the Glaessner article(1 975) suggested the establish& Middle Hecla Hoek) in Ny Friesland (Semik ment of the base of Cambrian at the appearance hatov 1976). In addition to the typical forms, of shelly fossils. Raaben (1969) has described lnzeria hunn Preliminary results of studies of acritarchs bergiana from Nordaustlandet and l. ny from the Grasdal Formation suggest Vendian frieslandica from Ny Friesland, and Krasil and not Upper Riphean age (G. Vidal, pers. shchikov (1 973) has reported from the Hunn comm. 1977). There are as yet no data on the berg Formation Gymnosolen murchisonicus, ln microfossil assemblage of the Porsanger Dolo zeria chunnbergica (possibly a different speiling mite. of l. hunnbergiana), l. blingica, and Tungussia Summing up, we propose that the Porsanger sp. A subsequent identification ofPoludia russa, Dolomite and the Grasdal Formation constitute Boxonia aff allahjunica, and Conophyton sp. in parts of the same carbonate province but are not the Backlundtoppen Dolomite which forms the exactly time correlative. It would seem probable uppermost portion of the Middle Hecla Hoek that the carbonate province was first established (Akademikerbreen Group) in Ny Friesland has in the northwest where the Porsanger Dolomite been made by Raaben Zabrodin (1 972). This was deposited, and then later in south-eastem sugge sted a late Riphean/V& endian age for the areas. Backlundtoppen Dolomite although e.g. Krasilshikov (1969, 1970, 1973) and Sokolov (1973) considered the base of the overlying glacigene deposits as marking the beginning of Correlation with Vendian time. other Late Precambrian Varangian tillites overlying the late Pre For mations of the Arctic cambrian carbonates in Finnmark, north Nor way, were for many years also considered to Correlations of Late Precambrian rocks based mark the beginning of the V endian period, on stromatolites rely essentially on type sections mainly on the basis of correlation with data from in the southem Urals where several distinctive the coastal Kola Peninsula and Russian Platform assemblages have been identified in carbonate (e.g. Keller Sokolov 1960, Keller et al. & formations (e.g. Keller 1963; for a review see I963:l l0, Roberts 1974, Siedlecka 1975). On the Semikhatov 1976). An assemblage such as other hand, both the stromatolite assemblage Gymnosolen ramsayi, lnzeria djejimi, and Cono described in this paper and the assemblage of phyton miloradovici is typical of the U pper acritarchs (G. Vidal pers. comm. 1977, 1978, see Riphean of the Urals and has also subsequently pp. l, 24) indicate that the Riphean/Vendian been found in Polyudov Ridge, southem Timans, boundary in Finnmark does not coincide with NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromatolitesfrom Finnmark 25 the conspicuous lithostratigraphic boundary but ment of comparable assemblages of columnar is located within the subjacent sequences. This is stromatolites. Since this has not been the case in probably also the case in Spitsbergen. Similar the Arctic regions discussed here, a comparison ideas on the position of the Riphean/V endian of characteristics of stromatolites from the dif boundary in the discussed Arctic regions based ferent areas provides only a rough approxima on a variety of evidence are to be found in tion of their stratigraphic relationship and sug Raaben & Zabrodin (1969), Chumakov (1971) gests an U pper Riphean/Vendian age for the and others. investigated formations of Finnmark. The overall lithostratigraphic similarity be Similarities between the stromatolites of the tween the upper Middle Heda Hoek of Spits Eleonore Bay Group of East Greenland and bergen and the Tanafjord-Porsangerfjord those of the Porsanger Dolomite seem to be Groups of Finnmark is striking (e.g. Siedlecki much doser than the similarities with assem 1975). As shown above, the stromatolites pre blages of the above-discussed regions. The sent in the upper, carbonate formations of these Limestone-Dolomite Series constituting the top rock units indicate that they are also correlative. unit of the upper Eleonore Bay Group contains Accepting the idea that the Late Precambrian Jurusania sp., while in the underlying tillites mark a widespread glaciation (e.g. Wilson Multicoloured Series new forms of Poludia, & Harland 1964, Harland 1965) which was Eleonora, and Inzeria have been identified synchronous at least throughout the Arctic re (Bertrand-Sarfati & Caby 1976), an assemblage gions, it may be assumed that the top portions of generally suggestive of late Late Riphean age. the carbonate formations are time-equivalent. If On the basis of certain comparisons with Spits so, the differences in thickness between the bergen showing an absence in the Limestone carbonate formations in Spitsbergen and in west Dolomite Series of typical Riphean forms and a and east Finnmark ...:·all subjacent to Varangian dose similarity between the Poludia forms of glacigene deposits and ail representative of Spitsbergen and NE Greenland, it has been carbonate platform accumulations of approxi tentatively conduded that the stromatolite-bear mately the same rate of deposition - suggest that ing formations of NE Greenland are Vendian in a carbonate province was first established in age (Bertrand-Sarfati & Caby 1976). A final con Spitsbergen. The total thickness of the Back dusion cannot be reached yet, however, because lundtoppen Dolomite and the underlying Back there are no common forms in the Greenland and lundtoppen Oolite is ca. 600 m and the total Spitsbergen assemblages and comparisons were thickness of the upper Middle Hecla Hoek made only at the group levet. On the other hand, carbonates is in the range 1500-2000 m (Harland the acritarch assemblage is suggestive of Late 1961, Wilson 1961). Later carbonates started to Riphean age for the Multicoloured Series, latest accumulate in the site of deposition of the Riphean for the Limestone-Dolomite Series, and Porsanger Dolomite, ca. 200-250 m thick, and Vendian for the overlying Tillite Group (Vidal finally in east Finnmark represented by the 1976). Thus, the problem of the precise location Grasdal Formation. Further to the south-east, on of the Riphean/V endian boundary in NE Green the Aynov Islands, Rybachij Peninsula and land is, as yet, not finally resolved. It is worth Kildin Island, carbonates are even more re noting that there is a very dose relationship stricted (e.g. Keller & Sokolov 1960, Keller et al. between Inzeria groenlandica (upper Mul 1963, Bekker et al. 1970). This trend in the ticoloured Series) and l. sinopivarra, and be development of the carbonate provinces in the tween Eleonora ramosa (middle Multi Arctic regions seems to be reflected in the rela coloured Series) andE. laponica, and that the tive abundance and in the degree of variability of stromatolites of the upper Eleonore Bay Group the stromatolites. The most well-defined as and those of the Porsanger Dolomite exhibit the semblages and/or diagnostic forms are in Spits very same type of microstructure. The bergen and the least distinctive in east Finnmark stratigraphic implications of this latter feature and further to the south-east where, on Kildin are, however, not yet fully understood, although Island, only Gymnosolen (Collenia buratica the dose similarity between the algal stromato Maslov) has been described (Krylov 1959). This lites of these particular formations would suggest shows that not only the presence of correlative a common stratigraphic position for these rock carbonate provinces but also their considerable units. permanence are pre-requisites for the develop- In condusion, it is dear that even though the 26 J. Bertrand-Sarfati & A. Siedlecka NORSK GEOLOGISK TIDSSKRIFT l (1980) precise location of the Riphean/ V endian boun Bekker, Yu. R., Krylov, N. S. & Negrutsa, V. Z. 1970: The dary in the se Arctic regions is still uncertain, _the Hyperborean of the Aynov Islands, Barents Sea. Dokl. algal stromatolite assemblages testify to an ac A kad. Nauk SSSR 193, 80-83[In Russian]. Bertrand-Sarfati, J. 1972: Les stromatolites du Precambrien cumulation of Late Precambrian carbonates and supeneur du Sahara nord-occidental; inventaire, associated lithologies in a time span close to and morphologie et microstructure des laminations; correlations perhaps extending across this arbitrarily stratigraphiques. Publ. C.N.R.S.-C.R.Z.A., ser. Geo/. 14, established boundary. 240 p. Bertrand-Sarfati, J. & Caby, R. 1976: Carbonates et stromato lites du somme! du Groupe d'Eleonore Bay (Precambrien terminal) au Canning Land (Groenland oriental). Grøn. Geo/. Unders. 119, 51 p. Conclusions Chumakov, N. M. 1971: Wendian glaciation of Europe and the North Atlantic in the Late Precambrian. Dokl. Akad. Nauk The described stromatolite assemblage consists SSSR 198, 69-73[In Russian]. of five new forms and one new group. Cowie, J. W. & Glaessner, M. F. 1975: The Precambrian Among these forms none is common to the Cambrian boundary: a symposium. Earth Sei. reviews 11, Porsanger and Grasdal Formations. Based on 209-251. Føyn, S. 1937: The Eocambrian series of the Tana district, this observation and on other indications North Norway. Nor. Geo/. Tidsskr. 17, 65-161. (microfossils; debris of ? shells) it is concluded FØyn, S. 1960: Tanafjord to Lakselvfjord. 21• Internat. Geo/. that there is a difference in age between these Congr. Norden. Guide to AJ Exc. Nor. Geo/. Unders. 212a, two formations, the Grasdal Formation being the 45-54. Føyn, S. 1967: Big boulders of tillite rock in Porsanger, youngest. Northern Norway. Nor. Geo/. Unders. 247, 223-230. Comparisons of the Porsanger-Grasdal Gayer, R. A. & Roberts, J. D. 1971: The structural relation stromatolite assemblage with those of Late Pre ships of the Caledonian nappes of Porsangerfjord, W. Finn cambrian sections in USSR and Spitsbergen mark, N. Norway. Nor. Geo/. Unders. 269, 21-67. Golovanov, N. P. & Raaben, M. E. 1967: The counterparts of show that while it contains none of the typical the Upper Riphean in the Spitsbergen Archipelago. Dokl. U pper Riphean forms of the above-mentioned Akad. Nauk SSSR 173, 58-61[In Russian]. sections, some affinity with the Vendian of the Harland, W. B. 1961: An outline structural history of Spits Urals is detectable. bergen, InG. O. Raasch (ed.) Geology of the Arctic, Univ. Toronto Press, 68-132. Comparisons of the Porsanger-Grasdal Harland, W. B. 1965: Critical evidence of a great infra stromatolites with those of the Eleonore Bay Cambrian glaciation. Geo/. Rundschau 54, 45-61. Group in Eastern Greenland (presumed V en Hoffman, P. 1976: Stromatolite morphogenesis in Shark Bay, dian) reveal clear affinities. Western Australia. Developments in Sedimentology 20, 261- 271. Based on all the above considerations it is Holtedahl, O. 1918: Bidrag til Finnmarkens Geologi. Nor. concluded that the Porsanger and Grasdal For Geo/. Unders. 84, 314 pp. mations are of Vendian to late Late Riphean age. KeUer, B. M. 1963: Correlations of the Upper Precambrian sections of USSR with some sections abroad. In B. M. Acknowledgements. - The present paper is a result of a KeUer (ed.) Stratigrafia SSSR, Verhniy dokembriy, 604-608 research project carried out as part of IGCP Project No. 27 [In Russian]. 'Caledonide Orogen'. The work has been financially supported KeUer, B. M., Kopeliovich, A. V. & Sokolov, B. S. 1963: by Norges Geologiske UndersØkelse (AS), by Norges Almen Rybachiy and Sredniy peninsula and Kildin Island. In B. M. vitenskapelige Forskningsråd (field expenses of JBS) and by KeUer (ed.) Stratigrafia SSSR, Verhniy dokembriy, 103-113 Centre National de Recherche Scientifique (JBS). [In Russian]. We are indebted to Dr. S. Siedlecki for providing a sample KeUer, B. M. & Sokolov, B. S. 1960: Late Precambrian of the from the Grasdal Formation and for his guidance on outcrops northern part of Murmansk area. Dokl. Akad. Nauk SSSR of the stromatolite horizons in this formation, and to Drs. G. 113, no. 5, 1154-1157 [In Russian]. Vida! and M. R. Walter for their critical comments on the Krasilshchikov, A. A. 1970: Scheme for the Precambrian and manuscript. Mrs. R. Edwards and Dr. D. Roberts have kindly Lower Paleozoic stratigraphy of the Spitsbergen correctedthe English text. Archipelago. Dokl. Akad. Nauk SSR 194, no. 5, 97-100. November 1978 Krasilshchikov, A. A. 1973: Stratigrafia i paleotektonika Dokembria - rannego Paleozoia Spitsbergena. Tr. Nauchno International Geological Correlation Programme lssl. Inst. Geo/. Arktiki 172, 119 p. [In Russian]. Norwegian contribution No. 27 to Project Caledonide Krylov, l. N. 1959: Riphean stromatolites of the Kildin Island. Orogen Dokl. Akad. Nauk. SSSR. 127, no. 4, 888-891[In Russian]. Krylov, I. N. 1963: Stromatolites columnaires ramifies du Ripheen de l'OuralSud et leur importance pour la stratigrap References hie du Precambrien superieur. Tr. Geo/. Inst. Akad. Nauk SSSR 69, 133 p. Trad. B.R.G.M. 5431. Banks, N. L. et al. 1971: Late Precambrian and Cambro Krylov, I. N. 1967: Ripheah and Lower Cambrian stromato Ordovician sedimentation in East Finnmark. Nor. Geo/. lites of Tien·Shan and Karatau. Tr. Geol.lnst. Akad. Nauk Unders. 269, 197-236. SSSR 171,15 p[ln Russian]. NORSK GEOLOGISK TIDSSKRIFT l (1980) Columnar stromato/ites from Finnmark 27 Maslov, V. D. 1938: On tbe nature of the stromatolite Cono Serebriakov, S. N. 1975: Peculiarities of the formation and phyton. Problemy Paleont. 4, 325-328 [In Russian]. distribution of the Riphean stromatolites of Siberia. Tr. Monty,Cl. V. 1976: The origin and development of cryptalgal Geo/. Inst. Akad. Nauk SSSR 200, 173 p.[In Russian]. fabrics.Developments in Sedimentology 20, 193-259. Siedlecka, A. 1975: Late Precambrian stratigraphy and Playford, P. E. & Cockbain, A. E. 1976: Modem algal structures of the North-eastem margin of the Fennoscandian stromatolites at Hamelin Pool, a hypersaline barred basin in Shield (East Finnmark-TimanRegion). Nor. Geo/. Unders. Shark Bay, Western Australia. Developments in 316, 313-348. Sedimentology 20, 389-411. Siedlecka, A. & Siedlecki, S. 1971: Late Precambrian Preiss, W. V. 1973: The systematics of South Australian sedimentary rocks of the Tanafjord-Varangerfjord region of Precambrian and Cambrian stromatolites. Part Il. Trans. R. Varanger Peninsula, Northem Norway. Nor. Geo/. Unders. Soc. South Austral. 97, 91-125. 269, 246-294. Preiss, W. V. 1974: Tbe systematics of South Australian Siedlecki, S .. 1975: The geology of Varanger Peninsula and Precambrian and Cambrian stromatolites, PartIll. Trans. R. stratigraphic correlation with Spitsbergen and North-east Soc. South Austral. 98, 4, 185-208. Greimland. Nor. Geo/. Unders. 316, 349-350. Preiss, W. V. 1976: Intercontinental correlations. Develop Sokoiov, B. S. 1973: Vendian of Northem Eurasia. In Arctic ments in Sedimentology 20, 359-370. Geology,Am. Assoc. Pet. Geo/. Mem. I9, 204-218. Preiss, W. V. & Walter, M. R. 1975: Stromatolites of the Steinmann, G. 1911: Uber Gymnosolen ramsayi eine Co'elen Australian Precambrian: use in intra- and intercontinental terate von der Halbinsel Kanin. Bull. Soc. Geogr. Fin correlations. In Correlation of the Precambrian, Internat. lande, 3, 4, 18-23. Geo/. Correl. Progr. Symposium, Moscow 1975, 14-15. Sturt,B. A., Pringle, J. R. & Roberts, D. 1974: The Caledo Raaben, M. E. 1964: Upper Riphean stromatolites of the nian Nappe Sequence of Finnmark, Northem Norway and Polyudov Ridge and their vertical distribution. Bull. Soc. the timing of orogenic deformation and metamorphism. Nat. Moscou, Sec. Geo/. 39, 86-108 [In Russian]. Geo/. Soc. America Bull. 86, 710-718. Raaben, M. E. 1969: Stromatolity vierhnego Rifeja Tucker, M. E. 1977: Stromatolite biostromes and associated (Gymnosolenidy). Tr. Geo/. Inst. Akad. Nauk SSSR 203 [In facies in the Late Precambrian Porsanger Dolomite forma Russian]. tion of Finnmark,Arctic Norway. Palaeogeog. Palaeocl. Raaben,M. E. & Zabrodin, V. E. 1969: On the biostratigrap Palaeoecol. 21, 55-83. hic characteristics of the UpperRiphean of the Arctic. Dokl. Vida!,G. 1976: Late Precambrian achritarchs from the Eleo Akad. Nauk, SSSR 181, 671Hi79[InRussian]. nore Bay Group and tillite group in East Greenland. Prelimi Raaben, M. E. & Zabrodin,V. E. 1972: Algal problematic of nary report. Grøn. Geo/. Unders. Rap. 78, 19 p. the Upper Riphean (Stromatolites,oncolites). Tr. Geo/. Inst. Walter, M. R. 1972: Stromatolites and the biostratigraphy of A kad. Nauk SSSR 217, 129 p. [In Russian]. the Australian Precambrian and Cam'brian.Palaeonl. Assoc: Roberts, D. 1974: Hammerfest, beskrivelse til det l :250 000 London, Spee. pap. Palaeon/. Il, !90 p. berggrunnsgeologiske kart. Nor. Geo/. Unders. 301,66 p. White, B. 1968: The Porsanger Sandstone Formation and Roberts, J. D. 1974: Stratigraphy and correlation of Gaissa subjacent rocks in the Lakselv District, Finnmark, Northern sandstone formation and Børselv subgroup (Porsangerfjord Norway. Nor. Geo/. Unders. 255, 59-85. Group), South Porsanger, Finnmark. Nor. Geo/. Unders. White, C. B. 1969: The Stabbursnes Formation and Porsanger 303, 57-118. Dolomite Formation in the Kolvik District Northem Nor Schapovalova, I. G. 1968: On a new group of stromatolites way: the development of a Precambrian Algal Environment. Jacutophyton, from the Upper Proterozoic of the eastern Nor. Geo/. Unders. 258, 79-115. slopes of the Aldan anteclise. Dokl. Yakut. Fil. Sibir. Otd. Wilson,C. B. 1961: The upper Middle HeclaHoek rocks of Ny Akad. Nauk. SSSR 17, 97-103. Friesland, Spitsbergen. Geo/. Mag. 98, 89-116. Semikhatov,M. A. 1962: Riphean and Lower Cambrian of the Wilson,C. B. & Harland, W. B. 1964: The Polarisbreen Series Yenisei Ridge. Tr. Geo/. Inst. Akad. Nauk SSSR 68, 147 p. and otber evidences of late Pre-Cambrian lee Ages in [In Russian]. Spitsbergen.Geo/. Mag. 101, 198-219. Semikhatov,M. A. 1976: Experience in stromatolite studies in the USSR. Developments in Sedimentology, vol. 20 , 337- 357.