Lower Cambrian Trace Fossils from the Buen Formation of Central North Greenland: Preliminary Observations Ian D

Lower Cambrian trace fossils from the Buen Formation of central North Greenland: preliminary observations Ian D. Bryant and Ran K. Pickerill

The trace fossils Cruziana cf. C. stromnessi (Trewin, 1976), Curvolithus Fritsch, 1908, Hormosiroidea Schaffer, 1928, Monomorphichnus cf. M. bilinearis Crimes, 1970, Monomorphichnus lineatus Crimes et al., 1977, cf. Palaeobullia Gotzinger & Becker, 1932, Palaeophycus tubularis Hall, 1847, Phycodes pedum Seilacher, 1955, Psam michnites Toreli, 1870, Rusophycus Hall, 1852, Skolithos Haldeman, 1840 and cf. Zoophycos Massalongo, 1855 are recorded and briefly described from the Lower Cambrian Buen Formation, central North Greenland. Interbedded sandstones, silt stones and shales of the Buen Formation were deposited in a tide and storm dominated shallow marine shelf environment. Ichnofaunal diversity is low in mono lithologic cross-bedded sandstones, which characterise the basal portion of the se quence, and considerably higher in heterolithologic sandstones, siltstones and shales, which occur higher in the sequence.

I. D. B., Kon.lShell Exploratie Produktie Laboratorium, Postbus 60, 2280 AB Rij swijk (ZH), Nederland. Present address: Shell, BP & Todd ail Services Ltd., Private Bag, New Plymouth, New Zealand. R. K. P., Department of Geology, University ofNew Brunswick, Fredericton, N.B., Canada, E3B 5A3.

Seilacher (1956) was the first to recognise that trace This paper briefly describes aseleetion of trace fossils fossils could provide an important tool in correlating collected by I. D. B., as part of field work carried out by sparsely fossiliferous Precambrian to Lower Cambrian the Geological Survey of Greenland in 1984, from the sequences and potentially playan important role in the Buen Formation (middle to late Early Cambrian) ex establishment of the Precambrian-Cambrian boundary posed in the land area south of Nares Land, central on a global basis. Since then, more detailed analyses of North Greenland (fig. 1). Rusophycus marginatus Berg Precambrian and Cambrian ichnofaunas have been un str6m & Peel, 1988, reported by Bergstr6m & Peel dertaken from almost every continent apart from Ant (1988) from Peary Land, represents the only ichnospe arctica (see Crimes, 1987; Narbonne et al., 1987 for eies described previously from the Buen Formation. reviews). However, as noted by those authors, Pre However, Hurst & Peel (1979) illustrated Skolithos Hal cambrian and Lower Cambrian trace fossils are poorly demann, 1840 from Wulff Land and Peel & Christie known from Greenland. Cowie & Spencer (1970) de (1982) and Peel et al. (1982) also recorded its occur scribed aseleetion of Lower Cambrian trace fossils from renee in the stratigraphically equivalent Humboldt For the Bastion and Ella Island Formations of North-East mation of western North Greenland and the Dallas Greenland based on a few slabs collected during a re Bugt Formation of Inglefield Land. connaissance survey. Pickerill & Peel (1990) described a The present material comprises seven collections, significantly larger amount of material from the Bastion each carrying a Geological Survey of Greenland collec Formation and provided a taxonomic re-assessment of tion number (GGU prefix, Grønlands Geologiske Un the previous collections. Bergstr6m & Peel (1988) have dersøgeise). Figured specimens also bear a specimen also described several additional arthropod-produced number prefixed by MGUH and are housed in the trace fossils from the Lower Cambrian Dallas Bugt, Geological Museum, University of Copenhagen. In Buen and Humboldt Formations of northern Green view of the limited amount of available material, the land. To date, however, these are the only detailed trace fossils are not described using any rigorous or reports on Lower Cambrian trace fossils from Green formal taxonomic treatment. Rather, brief descriptions land. are given of the trace fossils present in individual sam-

Rapp. Grønlands geol. Unders. 147. 44-{j2 (1990) © GGU, Copenhagen 1990 45

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Fig. 1. Distribution af the Ruen Formation in North Greenland and gcographic location af IOCJlitics l and 2 as discusscd in thc (exl.

ples, which afe discussed stratigraphically. Examplcs of lian in northern Peary Land, in association with a di all ichnotaxa are figllfcd for future comparalive pur verse assemhlagc of poorly skeletised fossils (Conway poses. Morris el 11/" 1987; Blaker, 1988), Olenellids (Poulsen, 1974) and an undescribcd ncvadiid (J. S. Peel, personal Straligraphy communicatioll. 1989) occur in the upper part of the formation in southern Peary Land. indicaling thar the Cambrian shclf stratigraphy in North Grccnlancl is Buen Formation is af middle ro late Early Cam brian in reviewed by Peel (1982) and Higgins el al. (in press a, age. Overlying carbonates and siliciC!astics of the Brøn b). and describccl in detail by Tneson & Peel (in press). lund Fjord and Tavsens (skappe Groups yield trilobitc In southern Ordovician age. Protcrozoic clastics and carbonalcs. Tile formation At locality l. in lhe l::wd area south af Nares Land yields spira!!)' coiJed cyanobactcri<:l suggestive nf an (fig. J), lhe Bucn Formation comprises cross-bedded carly Carnbrian age (PeeL 1988) but fossils capable af glauconitic sandstones interbcdded with lhinly hedded providing a more precise age are lacking. Silicic!astic sandstones, siltstoncs and shales which pass upwards sediments af the overlying Buen Fonnation have into siltstoncs and shales (fig. 2). Dt:tailed palaeo-envi yielded Ilcvadiid trilobites near thc base of the forma- 1"01lt11ental interpretation af tbe succession is bcyond rhe 46

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Lithology

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~ Fig. 2. Scclion through part of fhe Buen • Formation. measured in an unnamed ~ " / land area south of Nares Land (fig. 1, "" '00 locality I). The oase of the seclion is 5 locatcd 1-2 m al10vc the base or the for W Illation. Samples discussed in tlle tcxt '" are indicafcd by GGU mlkctiOIl IlUlll "", hers.

sures adjacclll lU an unnamed glacier in an unnamed ~tratigr(lphically in vertical and bedding plane cxpo~ land arca south of Narcs Land (fig. I. iocality I). This ~urcs. A single dcscribed specimcn of the ichnogenus cf. sl'.rlion (fig. 2)

Fig. 3. Cruziana cf. C. srromnessi (Trewin, lY76) from GGU co!1cction 316939. a is MGUH 19.639 lInJ b is MGUH [9.640. Prcscf\'ation is in convcx hyporclicf. developed scratches or knobs which cxtcnd from the ured in Hiintzschel (1975. p. W09, fig. 43.3), is thc only axial furrow to the margins of the lobes. Rare examples ichnospecics of Hnrmosimidea in which the knobs ar arc smooth. Tht median furrow is clearly defillcd but pods are connceted by a narrow lhread af sediment. less deeply impressed lhan the lobes. A single canoe Crimes & Anderson (1985) therefore suggested two sllaped cxample (fig. 3a) attains il maximum width uf possibIe alternatives for tile mode af production af their 12.5 mm, which is uIlusual for an ichnospecies typically new ichnospecies N. canadensis Crimes & Anderson, less Ihan 5 ar 6 mm in width (Fillion & Pickerill, lY90). 19R5. In the first. tight vertieal meanders were arranged /-/ormosiroidea isp. (fjg. 4; GGU collcction 316939) is in Cl plane runIling through the line af burrows, \\lhile in preserved in concave cpirelief as Cl series af curved to Iheir second alternative a lower master burrow had slightly meandering disconncctcd dimples, 1 to 2 mm in vertient feeders. The material here suggests the former width and length and separated by 2 to 5 mm af undis alternative to be more plausible. Tn view af the limited lurbed sediment (fig. 4a). Tn convex hyporclierthe spec matcrial ([\VO examples) the trace is only identified at imens form a series af disconnected ar more rarcly tlle lchnogeneric level. Tile samples preserved in hypo~ connected pods af sediment; individual pods are l to 3 relief somewhat resemble Tllbercu/ichllllS Ksiq,zkicwicz, mm wide and up to IS mm in length but typically shaner 1977. However. according to the interpretation af (fig. 4b). As Iloted by Crimes & Anderson (1985) the Ksi,rzkiewicz (1977), [he pods in this ichnogcnus are not lype ichnospecies H. f/orenfiflQ Schaffer, 1928. as fig- connected so that there is 110 epirclicf cquiva1cnt and,

4 Rappon"r. [·n 50 51

Fig. 5. MonolJlorp!liclinlls cl'. M. biliflearis Crimcs, 1970; MG UH 19.642 and PaJaeophyws tIlbularis Hall, 1847; MGUH 19.643 from GGU collectioll 316939. Preservation is in convcx hypurelief an a sandstone sole. Note the thin lining (arrowcd), within P. !lI/mlaris, which c1carly posl-dales Morromorphichnus cf. M. bilinearis.

additionaHy, lhis ichnogenus is apparently restricted to the other, a feature that is uncommon in the material tlysch dcposits. Tbey alsa resemble .NeofJcreiles Sei here. Otherwise, the material is identical to M. bilinea lacher. 1960 figured by Fritz & Crimes (l98S, Pl

typical af Ihis icllJlogenus (see Hanrzschc1. 1975). ornamentcd, horizontal > thinly lined burrows up to I cm Monomorphichllus cf. M. bilif/earis (fig. 5; GGU col in diameter and 8 cm in length, with a burrow fill af lection 316939) is prcscrvcd in convex hyporelief and similar grain size to the enclosing sediment (fig. 5). A consists of straight to gently curved and paired parallel more detailed disClIssion of this ichnospccies may bc striae each approximately 1 mm wide and up to 7 cm in founu in Pcmberton & Frey (982). length. lndividual striae within a set are commonly Phycodes pedll!1l (fig. 6; GGU colleclion 316939) is equally, more rarely unequaIly, impressed and scpa prescl"\led in convex hyporelief. It consists uf straight, rated by I to 2 mm of undistllrbt:c1 sediment. lchnospec curved or looping, smootl1 burrow systems, each con ific assignment to MOllomOrphicllrllls cf. M. bilinearis is sisting af a main branch that bifurcates at short intervals Oll ly tentative because according to Crimes (1970) one 10 give minor branches; 'hese are l"alcate and pass stria within a set is typically morc deeply impresseJ than arolHld the main burraw and then upwards into the

Fig. 4. I--Jonnosiroidf'il isr,~ MG UH 19.041 from GGU collcction316939. a is tlle uppcr sllrt'ace ex pression whcrc prescrvlltion is in wncavc epirelid and Il is thc sole af the Sarthropods (see of the trace is consistent with an organism (?mollusc) fig. 6b). moving through the sediment just below the sediment Collection GGU 316935 was made almost 1 m higher water interface, thereby forming the median groove, in the section than GGU 316939, described above, and displacing sediment to either side and allowing some preserves a single example and a portion of a second of sediment to collapse back into the groove after its pas the ichnogenus Psammichnites Toreli, 1870, together sage. The second specimen consists of a small portion of with straight to curved epichnial grooves (see previous a single lobe (fig. 7a) and is not worthy of description. discussion of collection GGU 316930). Psammichnites GGU collection 316934 was made 0.9 m higher in the (fig. 7; GGU collection 316935) is preserved in positive sequence from a glauconite-rich, parallel-laminated, epirelief on the upper surface of a fine to medium fine to medium-grained sandstone (fig. 2). The lower grained, parallel-Iaminated sandstone. The beuer-pre surface possesses Palaeophycus preserved in convex hy served example consists of a 24 cm long bilobed trace, porelief similar to examples already described and also 2.3 to 3.2 cm in width and 3 to 4 mm in height, which possibie arthropod scratch traces. The upper surface of follows a straight to gently curving course (fig. 7). Indi the specimen exhibits narrow, short and unnamed ep viduallobes are smooth with steep outer margins which ichnial grooves and ridges, along with evidence of pri are slightly sinuous but clearly defined. Though typ mary current lineation and trace fossils tentatively iden ically smooth, a lobe at one end of the specimen exhibits tified here as cf. Palaeobullia Gotzinger & Becker, 1932 evidence of imbricated pads of sediment (fig. 7b). Each (sensu Miller & Knox, 1985) (figs 8, 9). The traces lobe is separated by an axial furrow, 3 to 4 mm in width comprise a series of gently curved to irregularly mean and up to 5 mm in depth and possessing a silty mudstone dering to looping and intersecting irregularly preserved infil!. The transverse cross-sectional shape is approxi epichnial grooves, 1 cm in diameter and of variable mately m-shaped. The longitudinal profile is slightly length. The grooves are only slightly impressed, U asymmetric as aresult of alternating more elevated and shaped and fianked by variably and irregularly devel more deeply impressed portions of the trace, similar to oped epichnial ridges, which in some instances assume specimens of P. gigas Toreli, 1870 recently described an almost lobate appearance (fig. 8). Weakly developed from the Lower Cambrian of New Brunswick, Canada, transverse ornament within the grooves is apparent in by Hofmann & Patel (1989). Though we assign this places, but only rarelyas they are more typically specimen to Psammichnites, we are reluctant to desig smooth. The fianking ridges vary in width from 1 to 3 nate an ichnospecific name in view of the fact that its mm. ichnospecies are in need of serious taxonomic revision. The traces are only tentatively identified as Palaeo In addition, the present material is limited and, perhaps bul/ia as they are generally nondescript furrows. This is more importantly, it is still not clear whether or not typical of Palaeobullia, however, when preserved as Torell's (1870) material is preserved in epirelief or hypo concave epireliefs (Miller & Knox, 1985). More typ relief (for discussion see Fillion & Pickerill, 1990). As ically, the ichnogenus, which Hiintzschel (1975, p. 106) such, Psammichnites may represent the senior synonym assigned to the morphologically variable 'Scolicia of Olivellites Fenton & Fenton, 1937 and possibly Lami group', possesses a well-developed median axis and nites Ghent & Henderson, 1966. However, it differs (cf. variably developed transverse ornamentation. How D'Alessandro & Bromley, 1987) from Aulichnites Fen ever, as discussed in detail by Knox & Miller (1985), the ton & Fenton, 1937 which does not possess alaminated presence or absence of these features is a refiection of

Fig. 6. Phycodes pedum Seilacher, 1955.; MGUH 19.644 (arrowed) from GGU collection 316939. a is a view of virtuaIly the complete slab and b is an enlargement of the upper central-Ieft portion. Note that although the minor branches are typically developed in a sinistral manner, some specimens develop a Treptichnus-Iike branching pattern. Smaller arrow denotes possibie arthropod scratch marks. Preservation is in convex hyporelief on a sandstone sole. 54 55

Fig. 8. d. Plllaeobullia isp.: MGUH 19.646 from GGU col1eccion 316934. Prcservation is in concave epirclicf on upper. currenl-lineatcd (arrowed) surfaee af il sandstone [ayer. Note thc al most lobe-like appearance af the outer ridges in one secliOll af thc trace (anowed). s,ubstrate consistency at the time af production by the bularis Hall, ]847, Rusophycus Hall. 1852 and Skolithos organislll \vhen moving across (he sediment surface. <.lnd J-1aldemann. 1840. Thesc are all illustrated in fig. IO. inJced. such features tTI<.lY or may not be present. Curvofithus isp. (fig. IO) consists af a curved trilobed Morphologi<:ally simiiar. though not identicaL lraces trace, 0.63 cm wicle and 2.6 cm in length. composcd af a have bccn observed from the Buen Formation lSO km srnooth central flattened area separated by very narrow to the ellst at the western end af Øvre Midsommersø, angular furrows from sharp and c\early defined margin Pcary Land, from npproximatdy SO m abovc its base (.J. al ridges, eaeh approximatcly just less than l mm in S. Peel. personal cornmullication, 1989; scc fig. Y) and width. Thc trace is smooth, lacking any ornamentalion. from the Dividal Group af arctic Norway (R. G. Brom Thc i(;hnogenus CurLJolithus is one that cxhibits consid ley, personal communil:<:ltioll, 1989). crable variation in form and prescrvational character Slightly less lhan 0.5 m higher in tbe seelion a speci· istics (e.g., see Heinherg, 1970. -1973) and is a candidate men reprcscnting l:ollectioll GGU 316938 was made for dctailcd taxonomil: revision (Fillion & Piekeril1, within parallel-laminatcJ. fine-grained sandstone (fig. 19(0). Thc IJnsiltisfactory taxonomic status and tlle faet 2). Thc sole af this spccimcn possesses several uni that only a single and smal! incomplctc specimen is dcntifiable biogenic struClures in addition to the foliow present in GGU collection 316938 predudes allY ieh ing ichnolaxa: Curvolithus Fritsl:h, 1905. Monomor nospccific assignment. phie/IIT/.1s fitJeatus Crimcs el al., 1977. Palaeophycus llI- Monon/orpllie/mus linearus (fig. IO) is also present as

Fig. 7. r.\'{I/lllnicilniles isp.: MGUH 19.645 from GGU collcClion 3]0935. Preservation is in convex cpirelicf an the upper surtaee of a sandstone layer; a exhibits the cornplct(; spccimcn ilnJ an incomplctc ponion ol' <-l single lobe at lIs top and b is an cnlargerncJlt ol' the Imver leff segment as observed in a. Note thc m-shapcd cross-section, the steep auler margins and the imiJricated ~cdirnent pllCls developcd in one ol' the lobcs (

Fig. 9. Fie Id photograph (courtesy of J. S. Pee!) ol' cf. PaJaeobuilia from ehe Bucn Formation at the western end af Øvre Midsommersø, Pcary Land, pre served in concave epirelief. Lens IlOOd is approximately 5 cm in dirHneler.

a single specimen, consisting af a single set af five mm in width, ol' variable length, parallel or sub-paralld isolated, straight to slightly curvcd ridges preserved in to stratification and preserved in positive hyporelief. An positive hyporelief. The ridges arc more ar Jess equally extremely thin silty mudstone lining contrasts markcclly spaced, each being approximately 18111111 in length and with the fine-graincd sanclstone infill, which is similar in the cBlire sct is approximately 22 mm wide. A detailecl grain size to the host rock. Tbe burrows intersect, giving discussion af the ichnogenus M0110tnmphichllus the impression of branching; otherwise. they are UI1 Crimes. L970 has recently been given in Fillion & Picke branchcd. [iII (1990) Rusophyc/ls (fig. IO) is present as a single poorly Pa/aeophyuls tubutaris (fig. 10) is present as a series prcscfV'ed and a single lTloderately preserved specimen. of straight. curvcd to sligbtly tortuous burrows, 2 to 6 both in convex hyporelief. The best examplc (fig. 10--4,

Fig. 10. Sandstone sole representing GGU collection 31693R. Presen'cd here are l. Cllrvolithus isp .. MGUH 19.647. 2. M01l01ll0rphidlf/l/s !ineatus Crirnes er al.. 1~77. MGUH [tJ.648, 3. PalaeophycliS Illbularis l-IalL 1847. MGLJH [9.649. 4. RIISOp!lYCII.\· isp .. MGUH 19.650 (upper right) and MGUH 19.651 and 5. Skolirlros isp.. MGUH 19.652. 57 58 below the scale) is an incomplete specimen, at least 49 long, 3 to 6 mm wide and possesses lamelIae composed mm in maximum width, and an incomplete length of 23 of alternating light and dark sandstone. The lamelIae mm. The specimen consists of two very shallowly im are variably developed along the length, are moderately pressed lobes, each possessing five or six more deeply to strongly arcuate and may attain a density of six per impressed transverse scratch traces, which extend over centimetre. In vertical section the structure is sub-verti the entire surface of the lobes. A single scratch is pos cal to inc1ined (c. 45°) and possesses avariably devel sibly bifido The median furrow is unfortunately not pre oped convex-upward spreite. The trace somewhat re served. The second specimen (fig. 10-4, upper right) is sembles Zoophycos Massalongo, 1855 to which it is 28 mm wide, at least 26 mm long, and similarly pos tentatively referred pending the availability of addi sesses at least six transversely oriented scratch markings tional material (R. G. Bromley, personal communi across the better defined lobe. This specimen has been cation, 1989). subsequently cut by the Curvolithus burrow. Both ex ampies are considered toa poorly preserved for ich Discussion and conclusions nospecific assignment. They are reminiscent of Ruso phycus avalonensis Crimes & Anderson, 1985, how The eleven ichnogenera recorded and briefly de ever, described from the Lower Cambrian of eastern scribed here represent the first trace fossils to be exam Newfoundland by Crimes & Anderson (1985) and Nar ined in any detail from the Buen Formation of central bonne et al. (1987) in that this ichnospecies is shallowly North Greenland apart from Rusophycus marginatus impressed, of 30 to 50 mm in width, and commonly has described previously by Bergstr6m & Peel (1988). The transverse bundles of five or more scratches. Specimens small amount of collected material and its rather var figured by these authors do not bear resemblance, how iable preservation has generally prec1uded ichnospecific ever, to the holotype of R. avalonensis (specimen GPIT assignment of most specimens and, in some instances, 1392/6, see Seilacher, 1970, fig. 7.3) selected by Crimes even confident identification at the ichnogeneric level & Anderson (1985) and more c10sely resemble R. latus has proven impossible. We feel that additional sam Webby, 1983 (Fillion & Pickerill, 1990). Accordingly, pling, particularly from different sections within the the specimens here also resemble R. latus and a taxo Buen Formation, would undoubtedly not only increase nomic reassessment of R. avalonensis seems necessary. the overall diversity of traces contained within the se Skolithos (fig. 10) is observed as isolated cylindrical quence, but would also perrnit a more accurate taxo and vertical unlined tubes, up to 8 mm in diameter, nomic assessment of the material described herein. intersecting the sandstone sole, with a structureless Nevertheless, the recorded assemblage compares fa sandstone fill of similar grain size to the enc10sing host vourably with other Lower Cambrian ichnoassemblages rock. The lack of longitudinal sections prec1udes ich reported from both Greenland (Pickerill & Peel, 1990) nospecific assignment (see Alpert, 1974). and elsewhere. GGU collection 316942, the stratigraphically highest The Lower Cambrian Bastion Formation of North sample collected from this heterolithic sequence (fig. 2), East Greenland has also yielded the ichnogenera Cru comprises a ripple-laminated glauconitic sandstone with ziana, Monomorphichnus, Palaeophycus, Phycodes, micaceous drapes. Trace fossils, possibly Palaeophycus Psammichnites, Rusophycus and Skolithos (Pickerill & tubularis, are preserved as straight to curved, isolated or Peel, 1990). Though Curvolithus, Hormosiroidea, cf. cross-cutting hypichnial ridges, 1 to 5 mm in width, of Palaeobullia and cf. Zoophycos have not been recorded variable length, and preserved in convex hyporelief. from the Bastion Formation, this latter sequence con Finally, as previously noted, a single specimen (fig. tains a far more diverse ichnoassemblage, probably be 11; GGU collection 271778) collected by J. S. Peel from cause of the much larger number of available and stud approximately 50 m above the base of the Buen Forma ied samples. With the exception of Palaeobullia, all of tion at the western end of Øvre Midsommersø, Peary the recorded ichnogenera have previously been re Land (fig. 1, locality 2), is also described herein. The ported from Lower Cambrian strata (see Crimes, 1987 specimen is an enigmatic penetrative plate-like spreiten for review). It is perhaps undcrstandable why Palaeo structure preserved on and within a fine to medium bullia has not been reported, as it is a morphologically grained sandstone. Hs upper surface (fig. Ub) is 52 mm variable ichnogenus resembling several other arthro-

Fig. 11. Specimens of cf. Zoophycos isp.; a. is a field photograph from øvre Midsommersø, Peary Land (courtesy of J. S. Peel). b, c, and d are various views of the same specimen (MGUH 19.653 from GGU collection 271778); b represents the upper surfaee expression and c and d lateral views. 59 60 pod-produced traces (Knox & Miller, 1985) and in ment typical of lower tidal flat and shallow subtidal cluded in the 'Scolicia group' by Ksicrzkiewicz (1970) environments possessed biogenic structures of a differ and Hiintzschel (1975). Scolicia de Quatrefages, 1849 ent morphology and lacking fine details in comparison sensu lato has been recorded from many Lower Cam to upper tidal flats, characterised by firmer substrates, brian sequences (Crimes, 1987, and references therein). which possessed contrasting traces (but produced by the The vertical distribution of the described trace fossils same organisms) that preserved fine morphological de is clearly related to lithofacies. Thus, the essentially tails (see also Pickerill et al., 1984, p. 435). A similar monolithologic cross-bedded sandstone lithofacies com example of the importance of substrate consistency in prising the basal portion of the sequence has only the controlof trace fossil morphology was given more yielded Skoljthos and Palaeophycus. Possibie reasons recently by Clausen & Vilhjålmsson (1986), from a for the low diversity have previously been outlined. Lower Cambrian sequence in Denmark. Indeed, at an Interestingly, the absence of funnel-shaped tops to the even broader level, Ekdale (1985) has suggested that Skolithos tubes (= Monocraterion Toreli, 1870) possibly even ichnofacies are substrate controlled. Although the suggests a subtidal rather than intertidal origin for much trace fossils described here are moderately well pre of the cross-bedded lithofacies (cf. Barwis, 1985; I. D. served, they do lack fine preservational details known Bryant and J. R. Ineson, unpublished information) or, from the same ichnogenera recorded in other sequences alternatively, may be aresult of truncation prior to which possibly suggests that substrates in the hetero deposition and stabilization of overlying sandstone sets lithic lithofacies were generally uncompacted and hence (cf. Goodwin & Anderson, 1974). possibly of subtidal origin. In contrast, heterolithologic sandstone, siltstone and shale lithofacies from higher in the sequence contain a moderately diverse ichnoassemblage, numerically dom Acknowledgments. The material was collected during the sum inated by dwelling (e.g. Palaeophycus) and foraging or mer of 1984 while I. D. B. was employed by the Geological feeding (e.g. Phycodes) structures. The influx of finer Survey of Greenland. F. SØrensen is thanked for his help in grained, particularly muddy material, and presumably a logging the described section and collecting the material. J. S. reflection of background lower energy conditions and Peellocated the section, provided us with additional material more stable substrates, was undoubtedly conducive to from the Buen Formation, photographed the specimens and exploitation by deposit-feeding organisms. Toponomic helped in the production of the manuscript. Technical assist preservation of their activity was presumably enhanced ance was provided by R. McCulloch, R. Northrup and D. Tabor of the Vniversity of New Brunswick. D. Fillion and R. by the availability of a variety of differing lithologies. G. Bromley read an early draught of the manuscript and for Skolithos is comparatively rare in this part of the se their constructive comments we are extremely grateful; use of quence compared to the cross-bedded sandstone litho isp. instead of ichnosp. as the standard abbreviation for ich facies, suggesting a relatively inhospitable environment nospecies follows the suggestion of R. G. Bromley. for infaunal filter feeders. The heterolithic lithofacies are interpreted to have been deposited on low relief, shallow subtidal areas between tidal shoals, or on intertidal sand flats (I. D. Bryant and J. R. Ineson, unpublished information). References Banks (1970), Crimes et al. (1977), Legg (1985) and Alpert, S. P. 1974: Systematic review of the genus Skolithos. J. Crimes & Anderson (1985) have described similar litho Paleont. 48, 661-669. facies associations from similar environments from Alpert, S. P. 1976: Trilobite and star-like trace fossils from the Lower Cambrian strata in, respectively, Finnmark, White-Inyo Mountains, Califomia. J. Paleont. 50, 226-239. Spain and Newfoundland, and all of which contain com Banks, N. L. 1970: Trace fossils from the late Precambrian and parable ichnocoenoses. Miller & Knox (1985) recorded Lower Cambrian of Finnmark, Norway. In Crimes, T. P. & a moderately diverse trace fossil assemblage from in Harper, J. C. (edit.) Trace fossils. Geol. J. Spec. Issue 3, terpreted tidal flat sequences in the Pennsylvanian of 19-34. Liverpool: Seel House Press. Barwis, J. H. 1985: Tubes of the modem polychaete Diopatra Tennessee. Vsing geological, present-day environmen cuprea as current velocity indicators and as analogs for Sko tal and experimental data, Miller & Knox (1985) and lithos - Monocraterion. In Curran, H. A. (edit.) Biogenic Knox & Miller (1985) elegantly demonstrated that syn structures: their use in interpreting depositional environ depositional sediment mass properties (particularly sed ments. Soc. Econ. Paleont. Min., Spec. Pub. 35, 225-235. iment consistency) varied between high and low tidal Bergstr6m, J. & Peel, J. S. 1988: Lower Cambrian trace fossils flat areas resulting in variable trace fossil morphologies. from northern Greenland. Rapp. Grønlands geol. Unders. They demonstrated that generally uncompacted sedi- 137,43-53. 61

Blaker, M. R. 1988: A new genus ofnevadiid trilobite from the and biogenic structures in environmental subdivision of a Buen Formation (Early Cambrian) of Peary Land, central Cambrian tidal sand body. J. Geo/. 82, 779-794. North Greenland. Rapp. Grønlands geol. Unders. 137, Gotzinger, G. & Becker, H. 1932: Zur geologischen Gliede 33-4l. rung des Wienerwaldflysches (Neue Fossilfunde). Geol. Clausen, C. K. & Vilhjålmsson, M. 1986: Substrate control of Bund. Wien Jahrb. 82, 343-396. Lower Cambrian trace fossils from Bornholm, Denmark. Hakes, W. G. 1977: Trace fossils in Late Pennsylvanian cy Palaeogeogr., Palaeoclimatol., Palaeoecol. 56, 51-68. clothems, Kansas. In Crimes, T. P. & Harper, J. C. (edit.) Conway Morris, S., Peel, J. S., Higgins, A. K., Soper, N. J. & Trace fossils 2. Geol. J. Spec. Issue 9, 209-226. Liverpool: Davis, N. C. 1987: A Burgess Shale-like fauna from the Seel House Press. Lower Cambrian of North Greenland. Nature 326, 181-183. Haldeman, S. S. 1840: Supplement to number one of'A mono Cowie, J. W. & Spencer, A. M. 1970: Trace fossils from the graph ofthe Limniades, and other freshwater univalve shelts late PrecambrianiLower Cambrian of East Greenland. In ofNorth America', containing descriptions ofapparently new Crimes, T. P. & Harper, J. C. (edit.) Trace fossils. Geol. J. animaIs in different classes and the names and characters of Spec. lssue 3,91-100. Liverpool: Seel House Press. the subgenera in Paludina and Anculosa, 3 pp. Philadelphia: Crimes, T. P. 1970: Trilobite tracks and other trace fossils from J. Dobson. the Upper Cambrian of North Wales. Geol. J. 7, 47-68. Hall, J. 1847: Palaeontology ofNew York, Volume I. Contain Crimes, T. P. 1987: ltace fossils and correlation of late Pre ing descriptions ofthe organic remains ofthe Lower Division cambrian and early Cambrian strata. Geol. Mag. 124, 97 of the New York System, (equivalent of the Lower Silurian 119. rocks of Europe). 338 pp. Albany: C. Van Benthuysen. Crimes, T. P. & Anderson, M. M. 1985: Trace fossils from late Hall, J. 1852: Palaeontology ofNew York, Volume II. Contain Precambrian - early Cambrian strata of southeastern New ing descriptions ofthe organic remains ofthe Lower Middle foundland (Canada): temporal and environmental implica Division of the New York System (equivalent in part to the tions. J. Paleont. 59, 310-343. Middle Silurian rocks of Europe). 362 pp. Albany: C. Van Crimes, T. P., Legg, I., Marcos, A. & Arboleya, M. 1977: Benthuysen. ?Late Precambrian - low Lower Cambrian trace fossils from Hiintzschel, W. 1975: Trace fossils and problematica. In Teich Spain. In Crimes, T. P. & Harper, J. C. (edit.) Trace fossils ert, C. (edit.) Treatise on Invertebrate Paleontology W. Mis 2. Geol. J. Spec. Issue 9, 91-138. Liverpool: Seel House celtanea, Supplement 1, 269 pp. Lawrence: Geo!. Soc. Am. Press. and Kansas Univ. Press. D'Alessandro, A. & Bromley, R.G. 1987: Meniscate trace Heer, O. 1876-1877: Flora Fossils Helvetiae. Die vorweltliche fossils and the Muensteria-Taenidium problem. Palaeontol Flora der Schweitz. 182 pp. Zurich: J. Wiirster & Co. ogy 30, 743-763. Heinberg, C. 1970: Some Jurassic trace fossils from Jameson Ekdale, A. A. 1985: Paleoecology of the marine endobenthos. Land (East Greenland). In Crimes, T. P. & Harper, J. C. Palaeogeogr., Palaeoclimatol., Palaeoecol. SO, 63-8l. (edit.) Trace fossils. Geol. J. Spec. Issue 3, 227-234. Liver Fenton, C. L. & Fenton, M. A. 1937a: Olivellites, a Pennsylva pool: Seel House Press. nian snail burrow. Am. Midi. Nat. 18,452-453. Heinberg, C. 1973: The internal structure of the trace fossils Fenton, C. L. & Fenton, M. A. 1937b: Burrows and trails from Gyrochorte and Curvolithus. Lethaia 6, 227-238. Pennsylvanian rocks of Texas. Am. Midi. Nat. 18, 1079 Higgins, A. K., Ineson, J. R., Peel, J. S., Surlyk, F. & Sønder 1084. ho1m, M. in press a: Cambrian to Silurian basin develop Fillion, D. & Pickerill, R. K. 1990: Ichnology of the Upper ment, North Greenland. In Trettin, H. P. (edit.) The In Cambrian(?) to Lower Ordovician Bell Island and Wabana nuitian region. The Geology of North America E. Ottawa: groups of eastern Newfoundland. Palaeontogr. canadiana (in Geo!. Surv. Canada. press). Higgins, A. K., Ineson, J. R., Peel, J. S., Surlyk, F. & Sønder Fritsch, A. 1908: Problematica Silurica. In Joachim Barrande, ho1m, M. in press b: Lower Palaeozoic Franklinian Basin of Systeme Silurien du centre de la Boheme (separate), 28 pp. North Greenland. Bult. Grønlands geol. Unders. Prague: Publ. from Barrande Fund by author and editor. Hofmann, H. J. & Patel, I. M. 1989: Trace fossils from the type Fritz, W. H. & Crimes, T. P. 1985: Lithology, trace fossils and 'Etcheminian Series' (Lower Cambrian Ratcliffe Brook For correlation of Precambrian-Cambrian boundary beds, Cas mation), Saint John area, New Brunswick, Canada. Geol. siar Mountains, north-central British Columbia, Canada. Mag. 126, 139-159. Geol. Surv. Canada Paper 83-13, 24 pp. Howard, J. D. 1966: Characteristic trace fossils in Upper Cre Gaillard, C. 1984: Bioturbation des sediments pelagiques du taceous sandstones of the Book Cliffs and Wasatch Plateau. Cretace inferieur dans le bassin Vocontien (Chaines subal Utah Geol. Mineral. Surv., Central Utah, Coal Bult. 80, pines merionales, France). Geobios, Mern. Special8, 205 35-53. 214. Hurst, J. M. & Peel, J. S. 1979: Late Proterozoic? to Silurian Ghent, E. D. & Henderson, R. A. 1966: Petrology, sedi stratigraphy of southern Wulff Land, North Greenland. mentation and paleontology of Middle Miocene graded Rapp. Grønlands geol. Unders. 91,37-56. sandstones and mudstone, Kaiti Beach, Gisborne. Trans. Ineson, J. R. & Peel, J. S. in press: Cambrian shelf strati Roy. Soc. N.Z., Ged/. 4, 147-169. graphy of North Greenland. Bult. Grønlands geol. Unders. Goodwin, P. W. & Anderson, E. J. 1974: Associated physical Knox, L. W. & Miller, M. F. 1985: Environmental controls of 62

trace fossil morphology. In Curran, H. A. (edit.) Biogenic Nares Strait: correlation between Inglefield Land and the structures: their use in interpreting depositional environ Bache Peninsula. In Dawes, P. R. & Kerr, J. W. (edit.) ments. Soc. Econ. Paleont. Min., Spec. Pub. 35, 167-176. Nares Strait and the drift of Greenland: a conflict in plate Ksi'J:zkiewicz, M. 1970: Observations on the ichnofauna of the tectonics. Meddr Grønland Geosci. 8, 105-115. Polish Carpathians. In Crimes, T. P. & Harper, J. C. (edit.) Pemberton, S. G. & Frey, R. W. 1982: Trace fossil nomencIa Trace fossils. Geol. J. Spec. Issue 3, 283-322. Liverpool: Seel ture and the Planolites-Palaeophycus dilemma. J. Paleont. House Press. 56, 843-881. Ksi,!zkiewicz, M. 1977: Trace fossils in the flysch of the Polish Pickerill, R. K. & Peel, J. S. 1990: Trace fossils from the Lower Carpathians. Palaeontogr. pol. 36, 208 pp. Cambrian Bastion Formation of eastern Greenland. Rapp. Legg, I. C. 1985: Trace fossils from aMiddle Cambrian deltaic Grønlands geol. Unders. 147 (this volume). sequence, north Spain. In Curran, H. A. (edit.) Biogenic Pickerill, R. K., Fillion, D. & Harland, T. L. 1984: Middle structures; their use in interpreting depositional environ Ordovician trace fossils in carbonates of the Trenton Group ments. Soc. Econ. Paleont. Min., Spec. Pub. 35, 151-165. between Montreal and Quebec City, St. Lawrence Lowland, Massalongo, A. B. 1855: Zoophycos: novum genus plantasum eastern Canada. J. Paleont. 58,416-439. fossilium. 52 pp. Verona: Antonelli. Poulsen, V. 1974: Olenel!acean trilobites from eastern North Miller, M. F. & Knox, L. W. 1985: Biogenic structures and Greenland. Bul/. geol. Soc. Denmark 23, 79-101. depositional environments of a Lower Pennsylvanian coal Quatrefages, M. A. de 1849: Note sur la Scolicia prisca (A. bearing sequence, northern Cumberland Plateau, Tennes De. Q.), annelide fossile de la Craie. Ann. Sci. Nat., ser 3, see, U.S.A. In Curran, H. A. (edit.) Biogenic structures: Zoo!. 12, 265-266. their use in interpreting depositional environments. Soc. Schaffer, F. X. 1928: Hormosiroideaflorentina n. g., n. sp., ein Econ. Paleont. Min. Spec. Pub. 35,67-97. Fucus aus der Kreide der Ungebung von Florenz. Palaont. Miller, S. A. 1889: North American geology and palaeontology Zeuschr. 10, 212-215. for the use ofamateurs, students and scientists. 664 pp. Cin Seilacher, A. 1955: Spuren und Lebensweise der Trilobiten; cinnati: Western Methodist Book Concern. Spuren und Fazies im Unterkambrium. In Schindewolf, O. Narbonne, G. M., Myrow, P. M., Landing, E. & Anderson, H. & Seilacher, A. (edit.) Beitriige zur Kenntnis des Kam M. M. 1987: A candidate stratotype for the Precambrian briums in der Salt Range (Pakistan). Akad. Wiss. Lit. Cambrian boundary, Fortune Head, Burin Peninsula, south Mainz, math.-nat. K!. 10, 11-143. eastern Newfoundland. Can. J. Earth Sci. 24, 1277-1293. Seilacher, A. 1956: Der Beginn des Kambriums als biologische Nicholson, H. A. 1873: Contributions to the study of the errant Wende. Neues Jahrb. Geol. Palaeont. Abhandl. 103, 155 annelides of the older Paleozoic rocks. Proc. Roy. Soc. 180. Lond. 21,288-290 (also Geo!. Mag. 10,309-310). Seilacher, A. 1960: Lebensspuren als Leitfossilien. Geol. Peel, J. S. 1982: The Lower Palaeozoic of Greenland. In Em Rund. 49, 41-50. bry, A. F. & Balkwill, H. R. (edit.) Arctic geology and Seilacher, A. 1970: Cruziana stratigraphy of 'non-fossiliferous' geophysics. Mem. Can. Soc. Petrol. Geo!. 8, 309-330. Palaeozoic sandstones. In Crimes, T. P. & Harper, J. C. Peel, J. S. 1988: SpirelIus and related helical!y coiled microfos (edit.) Trace fossils. Geo!. J. Spec. Issue 3,447--476. Liver sils (cyanobacteria) from the Lower Cambrian of North pool: Seel House Press. Greenland. Rapp. Grønlands geol. Unders. 137,5-32. Torrel!, P. 1870: Petrifacta Suecana Forrnationis Cambricae. Peel, J. S. & Christie, R. L. 1982: Cambrian-Ordovician plat Lunds Univ. Årsskr. 6, 1-14. form stratigraphy: correlations around Kane Basin. In Trewin, N. 1976: lsopodichnus in a trace fossil assemblage Dawes, P. R. & Kerr, J. W. (edit.) Nares Strait and the drift from theo Old Red Sandstone. Lethaia 9, 29-37. of Greenland: a conflict in plate tectonics. Meddr Grønland Webby, B. D. 1983: Lower Ordovician arthropod trace fossils Geosci. 8, 117-135. from western New South Wales. Proc. Linn. Soc. N.S. W. Peel, J. S., Dawes, P. R., Collinson, J. D. & Christie, R. L. 107, 59-74. 1982: Proterozoic - basal Cambrian stratigraphy across