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Ediacaran from the Innerelv Member (late ) of the Tanafjorden area, northeastern Finnmark

J. FARMER*, H. P. A. of and Sciences, University of California. Los 405 Hilgard Avenue, CA 90024, U.S.A. Institute of University of Box 558, 22, Sweden fur Postfach 102148, I, Germany Department of and Palaeontology, University, 13, 62, Lund, Sweden P.O. Box Trondheim, Norway

(Received March 199I accepted 29 August 199I)

- An Ediacaran assemblage dominated by an unidentified species of 1947,along with species of Sprigg 1947, Sprigg 1947, Fedonkin 1982, and Fedonkin is described the first time from Innerelv of the Formation exposed in coastal outcrops west of on Peninsula, in northeastern Finnmark, northern Norway. The assemblage is dominated by discoidal which share certain affinities with the cosmopolitan genera. and However, our specimens differ from these and other discoidal Ediacaran fossils in the absence of radial sculpture. This, with a basically concentric organization, are characteristics shared with from the Dividal Group of northern Scandinavia, the White and northwestern , along with discoidal from the Supergroup, Forest, England, and the , , . Our discovery of an assemblage within the Middle Innerelv Member provides support for previous suggestions of a late age for this sequence. This conclusion is consistent with the occurrence of early taxa, including the and the problematicalforms and in basal portions of the Lower Formation, within the same stratigraphic section. The lowest faunal in northern Scandinavia Zone, on the of the fossil in Member (Middle Sandstone of the Group, Scandinavia. is a distinctly chambered form that was probably pelagic. In contrast, and genera of the so-called plexus, comprise an informal grouping of probably benthic, taxa that radial and/or concentric organization. In light the nature of taxa, present difficulties in taxonomic interpretation and correlation, and the abundance of cyclomedusoids many Ediacaran assemblages, we suggest that the concept of the Zone,as originally for northern be broadened to include the genera the plexus, of the occurrences in the Member described herein. It is our hope that additional fieldwork provide a basis for refined taxonomic evaluations and biozonation.

Fedonkin, press), understanding Introduction of its stratigraphicand spatial distribution is becoming Our knowledge of the pre-skeletal history of increasinglyrefined (Glaessner, 1979;Hofrnann, 1988 cellular rests exclusively published Hofmann & in press). descriptions of about one hundred species that of the Ediacaran assemblage were first comprise the Ediacaran fauna, an assemblage of described in by (1930) and by bodied fossil of complex organization that are 1972, 1973). However, the strati- presently known from about 25 localities on five graphic and age significance of the was continents (Glaessner, 1984 Sokolov Ivanovskiy, first brought to attention by Sprigg (1947, 1985; Morris, Hofmann, 1988; based on occurrences in the Ediacara Hills, Flinders Walter, Although the phylogenetic and evolu- Range, . The probable of the tionary significance of this unique fossil assemblage assemblage was subsequently established late remains controversial Glassner, 1984 Bergstrom, Vendian (Germs, Knoll & Vidal, 1986). Since that 1989 Valentine, 1489 Walter, 1989 time the list of species and localities has continued to grow, and the fauna is now considered be global in * Present address: Research Center, Field, CA U.S.A. distribution. Previous occurrences are J. FARMER AND

detail elsewhere (Glaessner, 1979, 1984; Hofmann, The Ediacaran fauna is dominated by discoidal 1988; Hofmann in press). forms that, until recently, were generally regarded With the exception of a recently reported occurrence pelagic 1947, Glaessner Wade, ; of fossils from inter-tillite beds in the see discussion by Narbonne Aitken, 1990, 953). Proterozoic Windermere Supergroup of northwestern. However, recent work suggests that many Ediacaran Canada Narbonne, 1990; Hofmann, discoidal forms (including the cyclomedusoids) Narbonne & Aitken, a consistent feature of the benthic (Seilacher, 1984; Fedonkin, 1985a, assemblage worldwide is that it postdates 1987; Jenkins, Narbonne Aitken. glacial deposits of the late Proterozoic (Glaessner, It also predates the first appearance of The preservation of soft-bodied organisms usually shelly fossils of early age. A extinction requires special environmental conditions. However, of most Ediacaran forms appears to have preceded the Glaessner 984) has emphasized that the Ediacaran early Cambrian radiation (Fedonkin, In the fauna is not Under conventional models, East European and in the the preservation of soft-bodied organisms requires first appearance of Ediacaran fossils is tillites early mineralization, controlled by representing the Proterozoic (Varangerian) glaci- rate, the abundance of organic matter, and salinity ation, but the first appearance the putative (Allison, But lithofacies associations, modes of foraminiferan, preservation, and the diversity inferred lifestyles Glaessner, 1979). represented argue against the importance of such The generally age of the processes in Ediacaran based radiometric dates, brackets it within the The late Proterozoic was a unique time in range Ma (Glaessner, 1979). However, un- evolution, with an absence of preda- published zircon dates an earlier age of tors. limited of sediment by burrowing 565 3 Ma for the fauna of the Mistaken organisms, and low levels of atmospheric oxygen Point Formation, Newfoundland (Benus, (Glaessner, 1979 Walter, 1989).Extrinsic factors Although knowledge does not support a account, in part, far many of the unusual biological detailed stratigraphic based an Ediacaran 1982) and features fossils, the widespread occurrence of this distinctive (Fedonkin, c) of the Ediacaran fauna. However: assemblage has proposals for the formal recent and functional suggest that recognition of a (see the Ediacaran organisms may have also possessed discussion by Mount, 1989) termed the intrinsic properties which favoured their preservation, Vendian 1972: Sokolov & Fedonkin, including having been composed of stiffer materials Ediacaran (Jenkins, (Cloud than comparable living species Glaessner. and the having possessed a body The (Varangerian) and Ediacarian architecture (Seilacher, 2989). In addition, microbial have also been proposed as stages of the Vendian mats were more widespread during the Vendian and (Sokolov. 1973). Guidelines of may have enhanced the preservation of soft-bodied boundary working group forms by promoting early (Gehling, suggest that the Ediacaran assemblage should be Gall, considered in age (Cowie, but formal stratigraphic nomenclature and type localities 2. are still under evaluation (Harland 1982 Morris, 1987; Narbonne The late Proterozoic to early Cambrian sequences of The Ediacaran fauna as a whole has been described northern Norway, consist of from a variety of (Glaessner, 5000 of and shallow-water including shallow and carbonate marine strata (Reading, 1965 Siedlecka Iithotopes (Goldring & 1967; Germs, 1972; 1967, 1971 Siedlecka, 1985). the Fedonkin, 1981; Gehling, 1983; Jenkins, Ford & (Fig. I the stratigraphic Gehling, 1983, and this report), muddy, basin interval is subdivided, oldest to youngest, as (Narbonne Aitken, and sub- follows: the Vendian ; marine fan (Ford, Anderson & 1981; Siedlecka, Morris, Gibson, Tetter Fedonkin. 1984; (Vendian), Vestertana (late Cambrian), Benus, 1989; Most occurrences and Groups ). are preserved as soft-bodied impressions in General stratigraphic and age relationships have been sequences as either low established by the correlation tillites within the casts (hyporeliefs) on the bases of beds, or as and Mortensnes formations (Fig. 2) of the on the upper surfaces of beds (Glaessner Lower Vestertana Group (Edwards, 1975, Wade, Glaessner, 1984; Seilacher, These tillites are correlated to the late Proterozoic Finnmark 183

(= Varangian, or glaci- transgressive, fining-upward sequence believed to ation, recognized throughout Scandinavia represent a transition to shallow conditions (Reading Walker, 1966; Banks, 1970, addition to the framework 1973b). described above, a generalized frame- The Member is by Innerelv work has also begun to emerge 1985;Siedlecka, Member with a contact marked by the based primarily on (Vidal, 1979, presence of several dark, pyritic mudstones and tine- strornatolites & Siedlecka, grained, lenticular sandstones. On Digermul Pen- trace fossils (Banks, 1970, a; Crimes, insula, the Innerelv Member is about 275 thick arid and the first appearance of consists of two shallowing-upward sequences, each and other shelly fossils 1967; representing a transition from offshore marine (quiet 1967; Glaessner, 1979). basin, below wave-base), to wave-influenced, The youngest division of the Proterozoic is the subtidal and intertidal deposition (Banks, 1973 Vendian Period (Sokolov & Fedonkin, erected basal part of the Innerelv Member consists of green for sequences underlying the . and red shales containing occasional Stratigraphic criteria for defining the base of interbeds of fine-grained, red sandstone. Near Vendian remain controversial. As defined, (Fig. I), the Middle Innerelv Member the beginning of Vendian Period was placed at consists of interbedded greenish-grey shales and fine- the base of the lowest Varanger (Sokolov grained, ripple cross-laminated sandstones. Near the Fedonkin, 1984). Jenkins (1981) later proposed an top of the cycle, exposed just Period, based on the earliest appearance of north mouth the creek, Manndraperelv (Map metazoans. Cloud & (1982) independently sheet UTM coordinates 428 proposed an Ediacarian Period, with the base being 3 the sequence also thick of defined by the top of the youngest strata. medium to coarse, parallel-laminated sandstone, in The latter proposal has apparently been the most some cases displaying rippled tops and extensive broadly applied in practice, although not without deformation due to loading and slumping some difficulty in the type area within the East 14 of Banks, Individual beds wedge European Platform (Vidal & Siedlecka, out over a distance of so along strike. Geochronological criteria for recognition of the Orientations of ripple marks suggest a base of the Vendian are poorly constrained, with southwesterly directions. These sand- estimates generally between and 670 Ma stones are interpreted to represent deposition in (Fsyn, 1985; but see Vidal Siedlecka, 1983 for an current swept {upper regime), wave-influenced alternative viewpoint). For example, the interglacial environment. Sedimentary structures suggest Nyborg Formation which lies between the two sedimentation, perhaps in shallow tidal channels, in the region has followed by slumping and load deformation of yielded a whole rock date of654 7 Ma (Sturt, saturated sands. This interval is overlain by 14 of & Roberts, 1975; see Pringle, 1973) that greenish-grey, parallel-laminated siltstone, inter- is consistent with an estimate of 670 Ma for shales just bedded with or less thick beds of above the late Proterozoic of grained, ripple-marked sandstone (Facies 12of Banks, Australia (Coats & 1973b), believed to represent sedimentation in quiet In our study area. the oldest outcrops to the water, below wave-base. Formation exposed on the island: In the study area, strata of the Innerelv Member Areholmen, east of the Digermul Peninsula (Fig. 1). strike between and with dips between 19 On Areholmen, the Mortensnes Formation is a and W. A prominent cleavage, between comprised of chiefly dolomite clasts (some with and dipping W, intersects presumably derived from the bedding, and in finer-grained obscures underlying Grasdal Formation {Edwards, 1915, 1984). sedimentary structures, arid tends to limit bedding The upper part of the sequence is a dark grey shale plane exposures. However, the cleavage is pro- containing dropstones. nounced in the and sandstones, and The post-glacial history of northeast- primary structures and bedding plane features are ern Finnmark commences with the Lillevatn Member often visible. of the Formation. The contact with the The Innerelv Member is overlain by the Mann- Mortensnes tillite is not exposed, and lies the interpreted to be a fjord between the island of Areholmen and the upward, turbidite sequence(Reading &Walker, Digermul Peninsula (Fig. However, on the Locally the Manndraperelv Member consists of 190 m to the northeast, the of red, and Member consists of a basal quartz conglomerate conglomerate, with interbedded greywacke and overlain by grey, sandstones in a stone. The contact with underlying Innerelv 184 J. FARMER AND OTHERS

sandstone upper part. This sequence overlain by red and green shales, capped by a coarse- grained sandstone which marks basal draperelv Member.

3. Fossil assemblages and localities this study, we describe an assemblage of discoidal from shoreline outcrops of the Member of the Stappogiedde Formation Group) exposed along the east of Peninsula near (Fig. 1). We also a description of and small burrows, from shallow water of the Middle Innerelv Member exposed along the side of Varanger Peninsula (locality Finally, trace fossils and problema including are described from levels 9 16 m above the base of the Lower exposed immediately south OR Figure Map of the region northeastern showing the of coastal outcrops of Peninsula (Fig. ; coordinates: 449, 334, Proterozoic to Cambrian sequences along topographical map sheet 22351 1, Peninsula. Innerelv assemblage Member is on Peninsula is marked by the presence of a dark grey, pyritic shale, An assemblage, comprised primarily of containing stringers of fine-grained sp. 1947, but including un-

EXPOSURE

LEVEL

LEVELS lo da ne

Parallel bedded - 80 Soft MUD

Figure 2. stratigraphic section (left) for the late Proterozoic to early Cambrian sequences on Peninsula. Expanded section (centre) indicates position of within the Middle Member of the Formation exposed of to the right indicates the stratigraphic sampled, of zones is indicated by elevations in above (+) the top or below (- ) the base of a reference sandstone at the top of the coarsening upward cycle in the Middle Member. Figure 3. (a) ‘Cyclomedusoid assemblage from upper bedding plane surface of sandstone in Middle Member, north of Manndraperelva. Level: +40 Scale = 2.0 cm. (b) ‘Cyclomedusoid’ float in Middle showing faint sculpture. Same location above, bar = 0.5 cm. sp. Collected as a Ioose block from Middle Member along shoreline just north of the creek, Manndraperelv on Peninsula, region, northeastern Norway, Scale bar 1.0 LO from lower bedding plane surface (overhang) of medium-grained sandstone within uppermost Middle Member, north of Manndraperelva. Level: Scale bar = 2.0 cm. identified species of 1947, collections of the Department of Geology 1947, Fedonkin 1982 and and Palaeontology, University of tund, Sweden. Fedonkin 1980, was discovered in sand- studies of living groups provide stones and siltstones of the Middle Member important constraints evaluating fossil taxa. expased immediately north of Manndraperelva Artificially-produced fossils of living show a (Fig. 1). broad range of variation As noted previously, sedimentary structures and comparable to that observed among many relationships suggest deposition in a shallow, forms 1989).In fossilization experiments, the marine environment. The details of musculature are not preserved, (Fig. 2) lies the upper portion of the suggesting the observed morphological differences lower oftwo successive cycles that between and may be largely characterize the Innerelv Member in region and not necessarily indicative of (Banks, Illustrated specimens, identified by phylogenetic relatedness. The demonstrated the prefix LO, been deposited in the type of induced morphological 186 FARMER AND OTHERS

Figure 4. (lower specimen) and corresponding specimen) from the Middle north Scale bar = 2.0 cm. - 14 LO showing concentric features araund central tubercle, perhaps due to compaction. Middle Innerelv Member, just north of Scale bar = 1 m. LO 6396. Enlargement upper specimen, Figure in sandstone. Middle Innerelv Member, just north of on Peninsula. Note intersections of rock cleavages are oriented parallel to long axis of specimen, suggesting that the elliptical form is secondary. Scale bar = 1.0 Level: - 14 LO

in living suggests the need for caution preserved as both epireliefs and hyporeliefs (upper in assessing taxonomic classification of and bedding plane surfaces, respectively) in fossils. Given the generally poor state ofpreservation fine-grained, greenish-grey sandstones and siltstones. of the fauna described in report, species level About individuals were measured and photo- assignments are considered problematic. graphed in the field from thirteen strati- most cosmopolitan of the graphic levels. Of these, were in occurrences, Ediacaran discoidal (Wade, 1972; while the remainder were found on loose blocks. assignment of Bedding plane assemblages at levels +40 and the most abundant Innerelv form ?a, is + 1425 cm (Fig. 2) account for more than of the considered problematic, it to be most closely measured specimens and individuals, 1947. The fossils are The fossils haw an elliptical outline, and are bedding surface Middle Innerelv Member. just north Note tentacle impressions in (a). Scale bar for (a) = bar for (b) = 1.0 cm. - 50.5 in float block fine-grained collected Member north of Manndraperelva. Scale bar from float derived from the lower Member, about 0.5 south Manndraperelva. Scale bar = cm. LO typically subdivided into two zones by a single species have been referred, is a circular to prominent concentric furrow or ridge elliptical that has a surface which surrounds a pit or characterized numerous fine grooves, along tubercle, averaging 2.1 (range 1-6 in with a variable number con- ameter. A faint radial ornamentation is observed in a centric furrows which subdivide the surface into few specimens Fig. but most specimens show distinct regions (Sun, However, radial struc- only concentric features. The long axis of the discs tures are not present in specimens. For example, averages 5.05 = range: 2.2-17.8 cm), paratypes of this species lack radial grooves and have the short axis averages 3.50 = 1.77; concentric ridges only near the periphery (Glaessner, range: 1.412.5 The orientation of long axes for 1984; Sun, of Sprigg the bedding plane (average range by Wade (1972, pl. 41, fig. 1) lack radial to is roughly the strike of striations, as do specimens of sp. the (average to described by Narbonne Aitken (1990, figs suggesting that the shape is a secondary 2, figs 3, 5). The presence of such features may feature. depend on preservation (Sun, and pending variations conspicuous within revision of this genus, it seems unrealistic to base the many Ediacaran discoidal fossils, and identification of genera on the presence of absence of been applied very features (Narbonne & Aitken, 1990, p. 959). (Glaessner, 1984). For example, the type species, Occurrences of in the Windermere (Sprigg, to which most Supergroup of the Wernecke and

Of {Narbonne 1987; The specimen exhibits the smooth, disc and Aitken, 1990) contain a mixture of middle zone typical of but the outer zone, that show both radial and concentric elements. if present at all, is only faintly preserved. Our The common from the specimen resembles hyporeliefs of reported Member is characterized by a general absence of previously from Australia (Glaessner Wade. radial sculpture, and the presence of one or more the Mountains, Canada (Narbonne prominent furrows that subdivide the disc into distinct Hofmann, 1987) and the White Sea region, regions. Typically, regionation is by a single deep (Fedonkin, 198I), is questionably assigned this furrow which divides the disc into two parts, genus pending further study. surroundinga central papilla. However, our specimens Two of our specimens (Fig. are to show neither the fine sculpture typical of Sprigg 1947 (Narbonne Hofmann, 1987; nor the fine concentric sculpture Narbonne Aitken, but differ in having of As noted above, whether absence of elliptical rather than circular outlines. The axis these features is due to preservation, or of of the specimens parallels exactly the strike of the actual taxonomic differences,remains uncertain. How- {Fig. suggesting that the elliptical form is ever, based on the above diagnosis, our specimens a secondary feature, Both surfaces are characterized appear to be allied most closely with the by a smooth, flat disc with a elevated margin, complex (Sun, and are provisonally placed surrounding a central papilla. The of any regular with that genus, pending further study. concentric or radial is (1990, 959) interpret although some of our specimens do exhibit as a conical form that concentric features which may be due to compaction with the surface permanently attached to the and flattening of the central papilla Fig. 4b). substrate at the position of the central Narbonne Nofmann (1987, 666) suggest that Interestingly, where large aggregations of individuals Beltanellifarmis-type discoidal fossils were originally are preserved on bedding planes in the in no globular forms that 'attached to the seafloor. case were the discs observed to cut across one another. Four specimens resembling Fedonkin This is suggestive that individuals have been 1982 were discovered on a single bedding surface in living attached to the bottom, rather than accumu- fine-grained siltstones at fossiliferous level -50.5 cm lating there passively before burial. The specimens are preserved as Iow 1947 is the largest and consist of a smooth central disc averaging 1 discoidal fossil known from the assemblage in diameter 0.85-1.2 surrounded by an (Glaessner Wade, 1966; Narbonne Hofmann, irregular fringe of overlapping tentacle impressions 1987). It is characterized by a basic tripartite organiz- (Fig. b). This genus was reported from ation in which the smooth surface is the of White Sea region (Fedonkin, 1982, subdivided equal portions by two prominent and furrows. In the type specimens, radial furrows are Discoidal fossils were also discovered south of present, but only on the surface. In Manndraperelva, in float derived from the Lower addition, their distribution is to the Innerelv Member. The discoidal, outer zone (Glaessner Wade, Sun, elliptical in outline and occur on the bases of The central region of the disc is smooth, slightly grained, red sandstones (Fig. They range in size elevated, and lacks the central papilla typically from 1.3 to 2.7 (long axis), and possess a well- observed in We recovered a single, defined outer ridge (range wide) sur- partial specimen (Fig. from float derived from the rounding a slightly depressed central area. Com- interval just north of parable fossils were also found in fine-gained sand-

Figure (a) Pseudofossils.Small pillar structures preserved in on upper surface offine-grained,ripple sandstone from the Middle Member, Kvalneset. west (Note that similar structures from this (Banks, were previously interpreted burrows). Scale bar = 0.5 (b)Transverse thin section of pillar structures shown in Figure reveals that the features penetrate several into underlying bed Orientation of clay stringers suggests fluidization and upward movement of sand into layer. Middle Member, Kvalneset. Scale bar = 0.5 cm. 6407. Pillar structures preserved on of ripple cross-laminated sandstone of Middle Innerelv Member, Kvalneset. Scale bar LO (d) Pseudofossils. Casts of structures similarto those in Figure preserved in on base offine-grained sandstone. Middle Member, Kvalneset. Scale bar = 0.5 LO (e) resembling (left) and (right). Enlargement of pillar structure in Figure (right) preserved on of fine-grained, ripple sandstone of Middle Innerelv Member at Kvalneset. Varangerfjorden. Scale = 0.5 cm. LO Thin section of large specimen shown to left in Figure 6e. in fine-gained sandstone show disrupted laminae in upper part and sand penetrating upward into overlying shale layer. Interpreted to be a structure formed by Innerelv Member, Kvalneset. Scale bar = 190 FARMER AND

stones of the Middle Member, north of thin section, the structures are filled with (Pig. The fossils from these grained sandstone derived from the underlying localities resemble They have shallow, cylindrical cross-sections described from the ‘Series’ of the White Sea deform the overlying shale in an region, and more recently from inter-tillite beds in the direction (Fig. Thecores structures Windermere Supergroup of Canada vertically oriented stringers which can Narbonne & Aitken, Pending traced downward into the underlying sandstone bed further study, we questionably assign our Lower or more. The features are interpreted to specimens to this genus. small-scale fluid-escape structures, or ‘pillars’ formed by the dewatering of water-saturated sands. This interpretation is consistent with the occurrence of climbing ripples with drapes, convolute bedding, The superficial similarities that exist between certain other features which suggest sedimentation classes of inorganic sedimentary structures and body ofwater-saturated sediment Lopiccolo, 1974: fossils of simple form are among the earliest 1975). in The proper assessment of Larger features, which resemble the origin is especially important in Precambrian (Glaessner & Wade, were rocks where record is non-skeletal. The re- collected from both and upper surfaces of fine- semblance of discoidal fossils grained sandstone beds at Komagenes (Fig. In to thin section, the features are underlain by zones of sedimentary features structures produced by disrupted lamination that penetrate several watering or sediment loading) has been noted pre- into the bed (Fig. these viously (Webby, 1970; Cloud, 1980: zones, shale been deformed and bent Sun, Within the of similar upward, apparently by the fluidization and upward precautions should be especially among movement ofthe sand prior to The zones trace which are typically simple. of deformation typically originate crests. small, non-branching found on bedding The association of these features with climbing ripples vertically structures resembling and convolute lamination argues strongly for an burrows are some bedding plant inorganic origin the dewatering of water-saturated exposures of the Middle Member which sediment. out along the shoreline on the side of the Varanger Peninsula, Kvalneset (locality Trace fossils and Komagenes 12; Banks, 1973 Vidal, The contact between the Manndraperelv Member and At the Member consists of Lower Breivik Formation is exposed in coastal fine sandstones (up to 20 thick) showing outcrops immediately south of (Fig. ripple cross-lamination, climbing ripples. and thin coordinates : 449, topographical map sheet mudstone interbeds 4 of Banks, Small 2235 The Upper Manndraperelv burrows, assigned to the ichnogenera Member is characterized by medium-grained red and were described previously sandstones, with ripple-marked tops, and thinner from at Kvalneset (Banks, 1970, interbeds of wavy-bedded, ripple cross-laminated. fine 1973 and are reportedly the oldest trace fossils sandstone and siltstone. The contact with the Lower in northeastern Finnmark (Crimes. 1989). Vertical Breivik is identified by several thick, burrows are in stratigraphic sequences massively bedded, medium- tocoarse-grained, older than Lower Cambrian, and presence in the green sandstones, with ball and pillow structures. Vendian of special interest in evaluating models for with thinner interbeds of sandstone the early ofthe (Valentine, 1989). showing cross-bedding, graded and wavy- The structures from Rvalneset are laminated, fine sandstone and siltstone. roughly circular in outline, 1-3 mm diameter, and Trace fossils are abundant the bedding surfaces thin shale partings between fine-grained, of bedded, fine sandstones and siltstones of the ripple cross-laminated sandstone beds (Fig. ‘The Upper Manndraperelv Member at association, and the absence of Rock cleavage, at a to other evidence of biological activity , makes of bedding surfaces difficult, bedding plane trace fossils, suggests the need for particularly in the thinner units. However, small caution in interpreting these structures. Oriented thin unbranched surface trails, and burrows sections of several representative specimens were oriented to bedding are prepared in order to evaluate better the origin of Ehe abundant at selected horizons on the lower bedding structures. surfaces of thin, fine-grained sand ripples in shale. I

191

About above the contact with the Lower Breivik Formation, trace assemblage is more diverse, and is dominated by larger forms, including and Our observations on the distribution of trace fossils in Manndraperelv and the Lower are in general agreement with previous published work for this region (Banks, 1970, However, new obser- vations suggest the following refinements: the burrow, known previously from the Middle Breivik, also occurs in the Lower Breivik; (2) the oldest undisputed trace fossils are small, burrows and simple surface that first appear in the Lower Manndraperelv Member. The latter conclusion is based on our evaluation of vertical reported from the Member, which we interpret to be inorganic. In addition to the trace fossil assemblage described above, filamentous, carbonaceous identified as were discovered on the upper surfaces of ripple-marked, fine sandstones about 10 above the basal contact of the Lower Breivik at along with carbonaceous annular tubes, tentatively assigned to (Fig.

4. Stratigraphic significance The lowest formally proposed faunal zone in northern Scandinavia is the Zone Glaessner, defined on the occurrence of the fossil medusoid, in Member (Middle Sandstone C) of the Group, northern Scandinavia & Glaessner, 1979). Glaessner Glaessner, is a chambered form that is separated, on that basis, from superficially similar forms comprising the (Sun, This species is com- parable to fossils which occur near the top of the Sandstone of central Australia and is probably late Glaessner, 1974; but see Jenkins, This is consistent with the first of the Lower Cambrian Eichwald in Member (Middle Shale of the Dividal Group 1967; 1967; Glaessner, and at a about above the base of the Lower Breivik Formation east of 1967) and on Peninsula (Banks, This

Figure 7. Carbonaceous tubes flattened by showing and rounded terminations. Discovered basal of the Lower Breivik Member Scales and specimen numbers: (a) scale bar = 1.0 LO 6402; bar = 0.5 LO scale = 1.0 LO 192 FARMER AND OTHERS

correlation is the first appearance described for the first time from the Innerelv of the early Cambrian and of the Stappogiedde Formation exposed in coastal in the Lower Breivik at outcrops on Peninsula, west of (Banks, 1970). in northeastern Finnmark. The assemblage Our discovery of an in the similarities to previously described occurrences of Middle and Lower Innerelv Member on Ediacaran fossils from the Charnwood Forest, Peninsula provides support for previous suggestions England (Ford, 1958, 1963, of a late €or this sequence, based on the Conception Group, acritarchs (Vidal, This general conclusion Newfoundland (Anderson & 1968 Anderson, also consistent with the occurrence of Lower Windermere Supergroup of the Cambrian taxa, including trace and Rocky Mountains of Canada and the problematical forms and (Narbonne Hofmann, 1987 Hofmann, Narbonne in basal portions of the Lower Breivik Aitken, 1990; Narbonne Aitken, 1990) and the Formation in the stratigraphic section. Dividal Group, northern The fauna of the Innerelv Member is dominated by Glaessner, and provides support for previously a discoidal that shares certain features with the described and correlations that suggest cosmopolitan genera, and but Vendian (late Ediacaran) age for the Innerelv Member which from and genera, in an (Siedlecka Siedlecki, 1971; Vidal, Within the absence of radial sculpture. These forms are included same sequence the earliest unequivocal trace fossils within the plexus (Sun, an occur within the lower part of the informal grouping of intergrading taxa that share a Member, consisting of small trails and common organization. burrows, preserved on the bases of and other discoidal forms Ediacaran fauna have thin sandstones. been variously regarded as medusae (Wade, This work is significant in providing a basis for 1968; Sun. as benthic ‘polyps’ (Fedonkin, more refined correlations of the stratigraphic interval Jenkins, 1988; Narbonne Aitken, as between the Mortensnes Formation (youngest the structures of sea-pens (Jenkins, and the first appearance of or as burrows of benthic (Seilacher, fossils In contrast, & Glaessner, 1979) is in the Lower (Banks, regarded as an unrelated pelagic (fur Fayn Glaessner, Based on the view see Seilacher, which possessed an occurrence of the along annular, chambered float similar to that of living with the problematic fossils, and chondrophorans, as (Jenkins, the boundary in 1984; Sun, 19860). These groups are generally study area is placed just above the basal of regarded as more primitive in organization than the Lower Breivik Formation. In the East European modern bilateral chondrophorans, and probably Platform, and precede the evolved during the early Ediacaran, appearance of and man by the Ediacaran (Jenkins, 1984). biotic components marking the In light of the present difficulties in taxonomic (Moczydlowska interpretation and present uncertainties in the cor- Vidal, 1986; Moczydlowska, However, the relation of the Ediacaran faunas of we ranges and suggest, as a working concept, that the extend well into the Lower Cambrian and overlap Zone, as originally defined with the ranges of both be broadened to include related form genera of the and the Avalonian Platform, the plexus, inclusive of the Innerelv earliest appearance of is taken to form described herein. It is our hope future work the base of the Cambrian (Narbonne al. will provide the needed data for a refinement of the 1987). However, the combined evidence from shelly biozonation of late Proterozoic sequences of north- and stable tope chemostratigraphy eastern Finnmark. et 1990 and work in progress) suggests that a higher boundary, located near the base Zone, may be preferable.

5. and conclusions Acknowledgements. The authors are grateful for critical comments on the manuscript by Simon Morris, An Ediacaran assemblage dominated by an un- F. identified discoidal form related to Guy M. and Malcolm Walter. Field and laboratory work was supported by generous grants from the Sprigg 1947, and including species of Natural Science Research Council for on-going 1947, Sprigg 1947. and research by Vidal, M. Moczydlowska, and P. Fedonkin 1982 and Fedonkin is and fieldwork by J. Farmer during August. 1989. NE I93

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