GFF Lower Silurian (Llandovery-Middle Wenlock ...

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Lower Silurian (Llandovery-Middle Wenlock) Chitinozoa and biostratigraphy of the mainland of Sweden Yngve Grahn a

a b

Dept. of Geology and Geochemistry , Stockholm University , Stockholm, Sweden

b

Dept. of Palaeozoology , Swedish Museum of Natural History , Stockholm, Sweden Published online: 06 Jan 2010.

To cite this article: Yngve Grahn (1998) Lower Silurian (Llandovery-Middle Wenlock) Chitinozoa and biostratigraphy of the mainland of Sweden, GFF, 120:3, 273-283, DOI: 10.1080/11035899809453218 To link to this article: http://dx.doi.org/10.1080/11035899809453218

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GFF volume 120 ( 1 9 9 ~pp. ) ~ 273-283,

Article

Lower Silurian (Llandovery-Middle Wenlock) Chitinozoa and biostratigraphy of the mainland of Sweden YNGVE GRAHN

Downloaded by [Lund University Libraries] at 05:09 28 April 2015

Grahn, Y., 1998: Lower Silurian (Llandovery-Middle Wenlock) Chitinozoa and biostratigraphy of the mainland of Sweden. GFF, Vol. 120 (pt. 3, September),pp. 273-283. Stockholm. ISSN 1103-5897. Abstract: Lower Silurian (Llandovery-hliddle Wenlock) chitinozoans from the mainland of Sweden have been investigated from the provinces of Skihe, VBstergotland, Ostergijtland and Dalama. Altogether twenty-three species from twelve genera, of which one species, Elicoriochiririn praeclaviJoniiis, is described as new, and four species left in open nomenclature are commented upon. A chitinozoan biozonation, with eight zones and subzones, for the lower Silurian of Sweden is proposed and compared with the graptolite zones. Keywords: Lower Silurian, Sweden, Chitinozoa, chitinozoan zones, graptolite zones. Y. Grnhti, Dept. of Geology arid Geoclierriistry,Stockliolrri Uriiversity, Stodholtti, atid Depr. of Palaeozoology, Swedish hftriseirtii of Natirml History, Stockholrir, Svederi. Present cickiress: Universidnde do Estado do Rio de Jarieiro, Facirldade de Geologin, Snln 4029 - Bloco A, Riin Sao Fraricisco Xnvier 524 (hfarncarin),20559-900 Rio de Jarieiro, R.J., Brazil, e-moil gmhri @ rrerj.br.hfnriiiscript received 25 Septerrrber 1996. Revised riiaritrscript accepted 14 hfny 1998.

Silurian rocks of the mainland of Sweden are predominantly of Llandovery and Early Wenlock age, and younger Silurian beds are only known for certain from the province of Skine. Conodonts, chitinozoans and to some extent also graptolites, acritarchs and prasinophycean algae have been used in the Middle to Upper Silurian biostratigraphy of Sweden, and the graptolite biostratigraphy is well known from the Lower Silurian beds. IIowever, except for the Gotland sequences the Early Silurian chitinozoans from Sweden are virtually unknown. From the mainland of Sweden they have earlier only been mentioned by Laufeld (1971, pp. 295-296, 1974, p. 56) and Grahn (1978). In this study the Llandoverian to Middle Wenlockian chitinozoans from the mainland of Sweden are discussed, and a biozonation for Llandoverian and Wenlockian beds of Sweden is proposed.

formed in the Late Devonian. The Silurian stratigraphy was discussed by Tornquist (1874, 1879, 1881, 1890, 1892), Bulman (1932), Waern (1960), Hutt et al. (1970), Jannusson (1982). and Loydell (1991). In Viistergotland the Silurian rocks are present on terraced plateau hills covered by a cap of dolerite. The plateau hills were downfaulted and had a low relief close to the erosion base during the latest glaciation, which prevented erosion. Linnarsson (1 868, 1869, 1877), Holm (1899), Johansson et al. (1913), Tornquist (1899n), Westergird (1928, 1931), Waern (1948) and Bergstrom & Bergstrijm (1996) have described fossils and lithologies. Silurian rocks in Ostergotland occur in a faulted area north of Motala between the lakes of Boren and Viittern. The geology was discussed by Tornquist (1875, 1899n). Linnarsson (1877, 1881). Wikman et al. (1980), and Bergstrom & Bergstrom (1 996). The Lower Silurian of S k h e is extensively faulted and has a “patchy” occurrence. Outcrops are concentrated to the southeastern part of the province, in the F i g e l s h g area, Rostinga, and Nyhamnsliige. Lower Silurian rocks are also known from deep drillings in the Mesozoic area of southwestern Skine (e.g. Bjerreskov 1986). Tullberg (1880, 1882), Kurck (1882). Moberg (1 893, 1910). Tornquist (1 897, 18996), Troedsson (1936), Nilsson (1946, 1979), Regndll (1960), and Grahn (1978) have published on the geology and stratigraphy.

Material and methods In all, 403 samples from Llandovery and Lower Wenlock rocks from 19 localities in S k i m , ViistergBtland, Ostergotland, and Dalarna have been investigated (Fig. 1). Altogether about 56.000 specimens of Chitinozoa were recorded. In general, their state of preservation is excellent. The stratigraphic position of the samples is shown in Figs. 2-14. All preparations of the material used in this study are deposited in the collections of the Swedish Museum of Natural History (RM), Stockholm, Sweden. SEM photomicrographs were taken on a Philips 515 at 15 kV.

Geologic setting

Localities, samples and chitinozoans

The Lower Silurian rocks of the mainland of Sweden are preserved as local rcmnants, isolated by erosion, from the Caledonian frontal zone in Jiirntland to Skine in the south. The occurrences in northernmost Sweden are poorly known and not further discussed in the present paper. The Silurian stratigraphy and lithology is comparatively well known from the province of JYmtland (Winian 1893; Thorslund 1938; Boucot & Johnson 1963; Bassett et al. 1982; Cherns & Karis 1995) and southwards (Fig. 1). The Silurian rocks in Dnlarna occur in a circular complex of downfaulted rocks surrounding a central uplift of the Proterozoic Dala granite. The ring structure is due to an asteroid impact

The investigated localities (Fig. l), with the samples and the chitinozoans recorded in each sample, are described below in alphabetical order with- UTM coordinates. Sample weights are about 50 g. Djurkiilla 1, hergotland (VE9975 9300). Shallow percussion-drilling about 4900 n~S of Nykyrka church. Topographical map sheet 8F Linkoping NV. Geological map sheet Aa 102 hlotala and Af 119 Linkoping NV. The drilling site was situated south of the road, and about 500 rn west of Lake Illersjon. The youngest Silurian beds in Ostergotland are known from this drilling. A sample at 27.00-31.50 rn yielded the following chitinozoan species of Late Llandovery or earliest Wenlock age: Arrcyrochitina ancyrea s.1.. Ancyockitina prittiitiw s.1.. Angochitino longicollis, Conochitina praeprobosci/era. and Cunucliitina ais6~ensir.

274

GFF 120 (1998)

Grahri: Lower Silrrriari Cliitiriozoa arid biosrrafigropliy of flit ~riairilaridof SwerleJi KALLHOLN 1

% s

Jarntland

i

SWEDEN

NORWAY Dalarna

c Downloaded by [Lund University Libraries] at 05:09 28 April 2015

T

@ DENMARK

?

Fig. 1. hlap showing the investigated localities of the mainland of Sweden. 1, Djurkiilln 1. 2, GullerSsen-Sanden I . 3. Kallholn 1. 4. Ljungliusen drilling 1.5, Lovisefred drilling 1.6, Nederberga I. 7. NyhamnsIiige 1. 8. Osmundsberget 1.9. Ostra Tommarp 1-2. 10, Rostinga 2-5. 11, Smedsby GSrd drilling 1. 12, Sodra Sandby drilling 20 and 27. 13, Solbega 1. 14, Stora Asbotorp drilling 1.

0

18.80

Gullerdsen-Sanden 1, Dalarna (WH 1020 7160). Locality situated along the little strcam Bysjoh at Gullerasen-Sanden. and about 7300 m NNW of Bods church. Topographical and geOlOgiCa\ map shcct l4F RSltvik SV. The locality was described by Waem (1960) and Thorslund & Jaanusson (1960). Samples ivere talten from the base of the M. rerahrfirs (= C. c)phirs) Zone, 0.5 m above the base of the same zone, and 1 m above the base of the C. gregoriirs Zone. All of these samples ivere barren of chitinozoans. The youngest Silurian beds at the locality correspond to the S. rrrrricitlafrrsZone. Kallholn 1, Ilalarna (VN 84-40 8170). Quarry about 7100 m W S W of Skattunge chapel in Skattungbyn. Topographical and geological map sheet 148 hlora NO. This is the type locality of the Kallholn Formation. Silurian shales from the C. gregciriirs Zone and hf. orgcrrferrs Subrone to 0. spirolis Zone crop out in the south wall of the quarry (Fig. 2). The locality was described by Thorslund 6r Jaanusson (1960) and Loydell(1991).

Ijunghusen drilling 1, Sliinc (UB 6778 4073). Deep drilling situated on the Falsterbo Peninsula about 4650 m E of Falsterbo church. Topographical map sheet IC Trelleborg NVl2C hlalmo SV. Geological m3p sheet Aa 112 Skanor. Drilling (T.D. 2280.24 m) made by the Geological Survey of Sweden. The main part of the \\.ell was performed as rotary drilling, and coring was made only at selectcd intervals. Altogether 43.66 m core was takcn, of which 20.42 m in Silurian strata (Fig. 3). The diameter of the cores was 105 mm in the Palaeozoic sequence. The Silurian beds (0.spirulis and C. lopwodri zones) are overlain by Lo\ver Triassic (Bunter) strata at 2149.37 m. The graptolites bvert: investigated by Roland Skoglund (unpublished).

F:.

C. gregarius Zone M. argenleus Subzone

Fig. 2. Lithology and sample levels in Kallholn 1. Dalama. No corrections have been made for the dip of the shales. Legend in Fig. 3.

Lovisefred drilling 1, Skin, (UC 4975 3497). Deep drilling situated about 1750 m S of Brunnby church. Topographical map sheet 3B HiiganYs N013C Hekingborg NV. Geological map sheet 3B HoganSs N0/3C Iielsingborg N V and Aa 78 IIBganS. Core drilling (T.D. 530 m) made by the Geological Survey of Sweden. The diameter of the core is 45 mm. The drilling penetrated lower Cyrtograptus Shale (C. cerifrQirgits Zone) and continued downwards into a diabase in the lower Didymograptus Shale (f.dciisrrs Zone). An interval from the base of the S.firrricrrlu~ics Zone to the base of the hf. rewhrfits (= C. cjphits) Zone (Fig. 4) was sampled (282.50-306.60 m). The graptolites \ v e x investigated by Ragnu Nilsson (unpublished). h'ederberga 1, Dalarna (VH 85 10 8260). No longer accessible ditch-sections about GI00 m W S W of Skattunge chapel in Skattungbyn. Topographical and geological map sheet 14E hlora NO. This is the type locality of the Nederberga Formation. One ditch was excavated in 1946, from the road to a point situated about 140 m south of the school. The contact betiveen the Nedcrbcrga Formalion and the Orsa Sandstone Formation \vas exposed near the road. It has not been possible to reconstruct the sampling levels in the 1946ditch. but the chitinozoansprescnt (Fig. 7) indicate an age of the Nederberga Formation not younger than the C. mitrcliisoni Zone. Ttvo additional ditches were excavated in 19-17, from the top of the 1946 ditch in direction S2"W (Fig. 5). and thereafter in direction S14"E(Fig. 6).

GFF 120 (1998)

Grdzrz: Lon-erSiliirinri Clzitiirozon nnd biostrntigrqihy of the rizairzlmd of Swederi

275

LOVISEFRED DRILLING 1

WUNGHUSEN DRILLING 1

Graptoliles

Chitinozoans

282 00 m C. lapworthi Zone

285 00 rn

S. turriculatus Zone

--r

t

- - - - - - -

M. convolutus Zone

290 00 rn

2186 22

?

295 00 m

2244 98


C. gregarius Zone

-aJm

0. spiralis Zone

c In e a m

cn

30000rn

zl

0

___---

r, 0 305 00 m

M. revolutus Zone (C. cyphus Zone)

30661 rn

,,,,,

Ouaternary deposits

Mudslone

Limestone

Shale

Nodular limestone

Sandstone

Fig. 4. Lithology and sample levels in Lovisefred drilling 1, Skbne. Legend in Fig. 3.

56.55 m

8a

Limestone nodules

W

-

Discontinuity surface Bentonite

6

Fig. 3. Lithology and sample levels in Ljunghusen drilling 1, Skbne. Legend for symbols used i n Figs. 24,8-14.

N~lianinsllge1. S k i m (UC 4685 3665). Outcrop at the beach about 3150 m W S W of Brunnby church. Topographical map sheet 3 8 Hoganss NO. Geological map sheet Aa 78 Hoganiis. A shallow drilling \vas performed in immediate connection to an outcrop aith shales corresponding lo the N.perscirlprits or P. aciriiiiiiufirsZone (Fig. 8). The Silurian beds of the locality have been described by 1-undgren (1874, pp. 158-159), Tornquist (1875. p. 57). Lindstrijm (1880, p. 9) and Grahn (1378. p. 14).

Osniundsberget I , Dalarna (WH 1145 6870). Abandoned quarry about 4350 m N of Bod3 church. Topographical and geological map sheet 141: Rsttvik SV. Lower Silurian shales and limestones, from the Al. sedgivickii or S. ritrricirlatirs zones to the Al.

c r i s p s Zone, crop out on both sides of the track at

the north entrance of the quarry (Fig. 9). The graptolites have been discussed by Thorslund R: Jaanusson (1960) and Hut: et al. (1970). The locality was also described by Jaanusson (1982). &tra Tornrnarp 1-2, S k h e (VB 5180 54445150). T\vo no longer accessible ditch-sections ca. 370 to 380 m W S W of Ostra Tomrnarp church. Topographical map sheet 2E Simrishanin SV. Geological map sheet Aa 109 Sinuishamn. The localities are situated at an abandoned purification plant close to Jiirrestadsin (Fig. 10). The former ditch (Ostra Tommap 1) yielded mudstones and shales from the Dalmanitina Beds to the M. r:yhrrirs (= C. cjpliitr) Zone. At the latter ditch (Ostra Tommarp 2) only beds corresponding to the Noniinlogropfirs perscrrlpliir Zone \yere sampled.

Grahn (1978) described the t\vo localities and the chitinozoans. The graptolites were investigated by Ragnar Nilsson (Fig. 10 herein, unpubl. material). Rostanga 2, S k h e (UB 9353 0648). Section at the rivulet Biiljane3 about 1000 m S W of Rosthga church. Topographical map sheet 3C Helsingborg SO. Geological map sheet A3 87 Trolleholrn. Only a few decimetres in thickness remain of the outcrop, and the rest is covercd by vegetation. A shale sample yielded a few. poorly preserved specimens of Coriocliifbin sp. This locality is number 12 of Tullberg (1880). and comesponds to IV h of hloberg (1910, p. 126). The graptolites were described by Tullberg (1882. p. 7). The shales belong to the Zone of Al. riccarfoiieiisi~. R o s t h g a 3, S k i m (UB 9360 0610).Section along the rivulet Biiljanei about 1050 m S of R o s t h g a church. Topographical map sheet 3C Helsingborg SO. Geological map shcet Aa 87 Trolleholrn. This locality (Fig. 11) corresponds to IV i of hloberg (1910, p. 126). The graptolites were described by Tullberg (1882. p. 7). The shales belong 10the Zone of C. riginirs. Kiistnnga 4, S k h e (UB 9360 0630). Section at the northeastern p3rt of the pond and close to a diabase about 1150 m S of RBstinga church. Topographical map sheet 3 C Iielsingborg SO. Geological map sheet Aa 87 Trolleholm.

GFF 120 (1998) NEOERBERGA 1

NEDERBERGA 1

s 2" w

S 14" E

374 80 rn

300.00 rn

E

lL

((I

e, W

e

W -0 W

€

z

U

la


P W

% 'D W

z

430 ao rn

374.80rn

early Wenlock?

early Wenlock?

Fig. 6. Lithology and sample levels in Nederberga 1 (1937), ditch in direction S 14"E.Dalama. No corrections have been done for the dip of the rocks. Legend in Fig. 3.

Fig. 5. Lithology and sample levels in Nederberga 1 (1937), ditch in direction S2"W. Dalama. No corrections have been done for the dip of the rocks. Legend in Fig. 3.

This locality (Fig. 12) is number 13 ofTullberg (1880). and ivas mentioned by hloberg (1910, p. 126). The shales belong to the Zone of C. rigidis.

RostAiiga 5, SkBne (UR 9306 0623). Section at the rivulet KvambScken about 1400 ni SW of Rosthga church. Topographical map sheet 3C Helsingborg SO. Geological map sheet Aa 87 Trolleholm. This locality is number 17 of Tullberg (1880). hlost of the locality is now covered by waste and vegetation. and only half a metre in thickness remains of the outcrop. Samples were collected at the base and at the top. The sample from the base yielded Cirigrrlocliitina sp. 1, Dcsrnochirina densa, Eirconoclririna praeclavifonnis nsp.. and hfargarliitina niargariiana, m d that from the top Ancyrochitiria ancyren s.1.. Cirigrrlochiriria sp. 1 and Errconoclri~iriapraeclavijonnis nsp. The graptolites were described by Tullberg (1882, p. 7). The shales belong to the Zone of hl. riccartonensis.

Sniedsby Gird drilling 1, Oslergotland (WE 0050 9190). Deep drilling situated about 3850 m NW of hlotala church. Topographical map sheet 8F Linkoping NV. Geological map sheet Aa 102 hlotala and Af 1 19 LinkBping NV. Core drilling F . D . 120.34 m) made by the Geological Sumey of Stveden (Fig. 13). The diameter of the core is 60 mm. The drilling site is about 1450 m east of \\.here astream from Lake lllrrsjon runs into Lake Viittern. Shales up to the Zone of ,If. crispirs are present. The Silurian of the drilling core \vas described by Wikman el al. (1980. pp. 95-97. fig. 41).

Sodra Sandby drilling 27, Skine (UB 9500 7675). Shallow drilling about 850 m W N W of Slidra Sandby church. Topographical map sheet 2C hfalrno NO. Geological map sheet Aa 92 Lund. A 20 m deep drilling made by the Cementa Co. in 1961. The drilling site is situated 160m northwest of Lindegkd farm (Fig. 14). The core was described by Grahn (1978) and Nilsson (1979). A continuous sequence from the Ordovician to the Lower Llandovery R. extenriatiis (= C. vesicrilosiis) Zone is present. Another shallow drilling, quite close to this one (Sodra Sandby drilling 20), contains a sequence from the Jerrestad Formation to the l o w r part of the P. aciirninatus Zone. All samples from the perscrrlpttts and acirrriinarirs zones yielded here Ancjrocliirina ancjrea s.1. and Cyntlroclririna sp. aff. carriparrrrlnefonri~s. Solberga 1, Dalarna (WH 1180 61 18). Abandoned q u m y about 2300 m SSEof Boda church. Topographical and Geological map sheet 141:Riittvik SV. Lower Silurian shales with limestone nodules occur on the southern slopes of a limestone mound. One sample from a limestone nodule at the base of the Silurim shales yielded Ancyrochirina ancyrea s.1.

Stora Asbotorp drilling 1, Viistergotland (VE 7468 3135). Drillsite situated about 2400 m N W of Skovde church. Topographical map sheet 8D Skara NO. Geological map sheet Aa 121 Skofde. Core drilling (T.D. 96.80 m) made by the Geological Survey of Sweden in cooperation with the Gullhogen Kalkbmk AD in 1945. The drilling site is situated about 375 m southeast of the south end of Lake Asbotorpsjon. The diameter of the core is 70 mm. The Lo\ver Silurian shales (0.80-12.80 m) in this drilling weresampledat0.80,2.00.3.00,4.00,5.25,6.30,7.20,8.47,9.49, 10.31, 10.79. and 12.80 in. The sampled interval corresponds to the uppermost S. rirrricrrlatrrs Zone to the 0.spiralis Zone. None of the samples yielded chitinozoans. The Silurian of the drilling core was described by Waem (1948, pp. 433473).

GFF 120 (1998)

Grdiri: Lower Silirrinri Chitiriozon arid biostrntigrnplty of the rrinirilnrid of S\i'eden

277


Fig. 7. Samples and chitinozonn species list from Nederberga I (1936). Dalarna.

Palaeontological notes Classification and terminology follow the proposals of Paris et al. (in press). The chitinozoans present were described and discussed by Laufeld (1974), Nestor (1994) and Grahn (1996). The known stratigraphical ranges of the species present in the investigated localities (cf. also Grahn 1996) are shown in Fig. 15. Remarks for the species in open nomenclature and a description of Ei~otiochitirzaprcleclavifonriis n.sp. are made below. Selected chitinozoans are illustrated in Fig. 16.

Order Operculatifera Eisenack 1972; Family Desmochitinidae Eisenack 1931; Subfamily Desmochitininae Paris 1981; Genus Desiiiocliitiiin Eisenack 1931

Eiicoiiocliit illQ pmecln vifori,iis n.sp. Fig. 16C-D, H. Drritwtiori of rinnie. - Latin, prne, before, refers to the overall similarity to Cotiocliitiiin cl~iviforrtiisEisenack 193 I , and the earlier occurrence of Eircoriochitirin prneclaviforrtris n.sp. compared to this species. Holotype. - RM Ch 129 (Fig. 16C).

Tjpe intend orid locality. - Cyrtograptus Shale, Zone of Cyrtogrnptirs rigidirs at Rostbnga 4. Dingnosis. - Eiicotiocliitinn species with a cylindro-conical body and a cylindrical neck about half the total length.

Desitiochitiiia sp. Fig. 16A.

Description. - The body is almost cylindrical with a convex base. The margin is rounded, and the maximum width is somewhat aperturalwards of the margin. Shoulders slightly convex, and the flexure weakly developed. The neck is cylindrical and the aperture is straight. The vesicle wall is smooth.

Reninrks. - Specimens similar to D. riiirior occur in the transitional beds between Llandovery and Wenlock at Nederberga 1 (Fig. 6) together with 6!nrgachitirin rriargnritnrin, Desrriochitiria derisa, Cythochitirin sp. aff. cnrii~~arzirlnefoniiis and others.

Diitieiisions (in pm, 260 specimens). - Total length 350-720 (holotype 7 10); greatest width (coeff. 0.7) 72-120 (holotype 119); width of aperture (coeff. 0.7) 76-1 16 (holotype 77); length of neck 160-300 (holotype 300).

Subfamily Pterochitininae Paris 1981; Genus Ciiigiilocliitiiin Paris 1981 Ciiigiilocliitiiin sp. 1 Fig. 16B. Retnnrk. - Specimens referred to C. sp. 1 have been described from the ceritrifigirs to the rigidirs zones in Bohemia as C. sp. A by D u k a et al. (1995) and Dufka (1995). Cirigirlochitirin sp. 1 occurs in the M. riccartorierisis Zone at Rostbnga 5, Skbne.

Order Prosomatifera Eisenack 1972; Family Conochitinidae Eisenack 1931; Subfamily Conochitininae Paris 1981; Genus E~icoriochitirinTaugourdeau 1966 restrict Paris et al. (in press).

Reninrks. - Eiicortochitiria prneclnvifontiis differs from Coriochitiria clnviforriiis and species in the Coriochitirin proboscifern group in not having a mucron. The species was included in the Coriochitirin aff. proboscifern coniplex by Laufeld (1974, p. 72). Nestor (1994) reported it as C. clriviforrriis pars. from contemporary beds in Estonia and north Latvia. It should be noted that C. clnviforrrris S.S. is a Late Silurian species. Occirrrence. - From the M. riccnrtoiietisis to the S. cliiitiner(i Zone in Skbne. A similar range is probably present on Gotland (cf. Laufeld 1974). Estonia and north Latvia (cf. Nestor 1994).

Subfamily Ancyrochitininae Park 1981; Genus Aiicyocliitiiin Eisenack 1955 Aiicyrochitiiin sp. aff. micyren A Fig. 16E. Retrinrks. - Aricyroclritirin sp. aff. (iricyren A occurs in the S.

278

Grnhri: h i r e r Siliirinri Cliitirioioa arid biostrntigrnplij of the rrinirilnrid of Sireden NYHAMNSLAGE 1

GFF 120 (1998)

OSMUNDSBERGET 1 0

T

M. crispus Zone

E

U C 0 E m

?

Y


a

Fig. 8. Lithology and sample levels in NyhamnslSge I , SkSne. Legend in Fig. 3.

E

tirrriciilotiis and possibly the Al. crispus zones at Osniundsberget 1. The species differs from A. oncyrea s.1. in having processes branching more than once. It also shows some similarities to A. rirrribaerisis Nestor 1994, although that species is restricted to the S. sedgwickii Zone in Estonia.

S . lurriculalus Zone

----?

U

E

.m .-

zul

._ (3

? 12.30m

Subfamily Cyathochitininae Paris 1981;Genus Cyntliocliitirin Eisenack 1955 Cynthochitinn sp. aff. cntitpnrii~lnefonllisur~i~is Fig. 16F.

Reninrks. - This species was commented on by Grahn (1995). The youngest known occurrence of Cjnthocliitiiin species is the latest Llandovery C. lapworthi Zone in Skim and, probably, Dalarna.

Chitinozoan biostratigraphy The chitinozoans present in the Lower Silurian of the mainland of Sweden and Gotland (Grahn 1995) can be arranged into eight zones and subzones. Each zone is defined by the first occurrence of the chitinozoan index species up to the first occurrence of the chitinozoan index species of the following zone.

Beloiiecliitirin yostrobtrstn Zone Defiiiitiori. - This zone corresponds to an interval from the first occurrence of B. yostrobirstn (Nestor 19800) in Sweden, to the first occurrence of Spirincliitirin rrinenriili (Nestor 1980b) or Coriochitirin nlnrgndn (Cramer 1967). It is also the total range of B. postrobiisto. Type iritend orid locnlitj. - The holotype was described from the Ohne Formation, Juuru Stage (Lower Llandovery), in the Ikla drilling (515.7 m), south Estonia. As the type interval and locality for the B. postrobiisto Zone in Sweden, the Rastrites Shale between upper P. nciirriiriotiis Zone and top Af. rciyoliitiis (= C. cyphiu) Zone at Ostra Tommarp, SkSne, is suggested. Clinrocteristic chitiriozoans. - Aricjrochitirin aricjrea s.1. and Cynthochitiria sp. aff. cn~rrpmiiilnefonriisdominate the zone on

Fig. 9. Lithology and sample levels in Osniundsberget 1, Dalma. Legend in Fig. 3.

the mainland of Sweden. On Gotland occur Coriochitirin iklricrisis Nestor 1980b and Rnriiochitirin sp. at the top of this zone. Kriowi occiirrences oiitsirle Swederi. - Beloriechitirici postrobrrstn has also been reported from Estonia and north Latvia (Nestor 19800, 1994), Belgium (Martin 1974), Bohemia (Duka 1992; Dufka & Fatka 1993), Saudi Arabia, Tunisia and southwest Algeria (Verniers et al. 1995), Canada, Quibec, Gasp6 (Asselin et al. 1989), and south China (Geng & Cai 1988).

Remarks. -The B. postrobiisto Zone in Sweden coincides in the graptolite biozonation to an interval from the upper part of the P. nctrrriirintirs Zone to the top of the A t revolirtirs (= C. cjphiis) Zone. In Estonia and north Latvia the B. postrobiuta Zone is defined as a partial range zone corresponding to the C. vesicirlosirs Zone (Nestor 1991). A similar definition of the B. poslrobiista Zone was made by Verniers et al. (1995) in a global Silurian biozonation.

Syiiincliitinn iiineniiili and Coiiocliitinnnlargcitln Zone Defiriitiorz. -This zone corresponds to an interval from the first occurrence of S. riinertriili (Nestor 1980b) and C. nlnrgndn (Cramer 1967) in Sweden, to the first occurrence of Cortochifirin witriastensis (Nestor 19820). Type intennl arid locality. -The holotype of S. rrineririili was described from the Saarde Formation, Raikkula Stage (Middle Llandovery), in the Ikla drilling (462.9 m), south Estonia. C. nlnrgnda was first described from the La Vid de Gordon section, about 66 m below the top of the Formigoso Formation, Cantabrian Mountains, Leon, Spain. As the type interval and locality

Grnliri: Laver Silirrinii Cliitiriozon a r i d biostrotigraphy of the rririirilorid of Swrlcri

GFF 120 (1998) OSTRA TOMMARP 1 - 2

ROSTANGA 3

I

Graptolites revolutus _R.M.-exteneatus --

-ti1

E--2 -- -- €-


279

m -

rigidus Zone

----

-

-P. acum&alE

N. persculptus

Fig. 11. Lithology and sample levels in Rosthga 3, SkSne. Legend in Fig. 3.

Fig. 10. Lithology and sample levels in h a Tonimq 1-2, Skbne. Graptolite biozonation after Ragnar Nilsson (unpublished). Legend in Fig. 3.

for the S. ninennili and C. alargadn Zone in Sweden, an unnamed formation in the C. gregnriiu Zone, Raikkiila Stage (Middle Llandovery), in the Niir drilling 1 (363.10-371.80 m), Gotland, is suggested. Clinracteristic cliitiriozonns. - In Sweden S. riineriiiili has not been found outside Gotland, but C. alnrgndn (Cranier 1967) is a diagnostic species in the same interval on the mainland of Sweden. On Gotland Coriocliitirin iklneiisis Nestor 1980b is a characteristic species within the zone. Cyntliocliitirin sp. aff. cnrrrpniiirlncfonnis, Ancyrochifirin micyrea s.1. (Eisenack 193l), A. priniitiw s.1. Eisenack 1964 and specimens similar to the two latter species are common. Kiionw occiirreiices oirtside Sweden. - Spirzacliitirin nineririili andor Coriocliitirin nlnrgacln are described from Estonia and north Latvia (Nestor 1980b. 1990, 1994), Ohio, USA (Grahn 1983, Canada, Qukbec, Gasp&(Achab 1981; Asselinet al. 1989) and Qukbec, Anticosti (Achab 1981), Spain (Cramer 1967), Saudi Arabia (Verniers et al. 1993, Libya (Hill et al. 1985; Paris 1988), and Algeria (Taugourdeau 1963).

Reniorks. - The S. iiiaerinili and C. alnrgarln Zone in Sweden corresponds to the Middle Llandovery C. gregariirs and M. convolirtirs zones. On Gotland is S. riineririifirestricted to the C. gregnriiu Zone. The stratigraphic level for the disappearance of C. alnrgndn in the mainland of Sweden is more uncertain (Fig. 15). In a global Silurian biozonation, Verniers et al. (1995) defined the S. inneririili Zone and the C. alnrgadli Zone as two separate biozones within the C. gregariirs and A t coiivoliitiis zones, respectively.

Type intend arid locnlity. - The holotype was described from the Rumba Formation, Adavere Stage (Middle Llandovery), in the Emmaste drilling (33.8 m), Hiiumaa, northwest Estonia. As the type interval for the C. eiiiiiinsteiisis Zone in Sweden, the lower part of the Kallholn Fomiation, Adavere Stage (Middle Llandovery), is suggested. No type locality is assigned. Clinracteristic cliitiiiozoaiis. - Eiserinckitirin doliolifnnriis Umnova 1976 and Coriocliitirin praeproboscifern Nestor 1993 occur for the first time at the base of the C. eiiiriinsteirsis Zone. Other characteristic and common species are Ancyrocliifinn nricyr-en s.l., A. priniitiw s.I., and Cyathochitinn sp. aff. cnnipriirlnefonnis. occirrreiicesoirtside Sweden. - Conocliitiiin errininstensis is also described from Estonia and north Latvia (Nestor 1982~1, 1993). Kiion.ii

Keninrks. -The C. eriiriinsteiisis Zone corresponds to the Middle Llandovery S. serlgnickii Zone. which is in agreement with the C. eiiirrinsterisis Zone defined by Nestor (1993).

Aiigocliitiiin loiigicollis Zone Defiiiitiori. - This zone corresponds to an interval from the first occurrence of A. lorigicollis Eisenack 1959 in Sweden, to the first occurrence of Eircoriocliitirin prnecfovifonriis nsp. It is also the total range of A. IorigicolfisEisenack 1959.

Tjpe intend niid locnlity. - The holotype was described from Upper Visby Beds at Visby cement works, Gotland. As the type interval for the A. lorigicollis Zone in Sweden, the upper part of the Kallholn Fomiation and the Nederberga Formation, Adavere and Iower Jaani Stage (Upper Llandovery-lowermost Wenlock), Coiiocliitiiin eniiiinsterisis Zone is suggested. No type locality is assigned. Definition. - This zone corresponds to the partial range of C. eiririrnsterisis (Nestor 1982n), from its first occurrence in Swe- Clinrncteristic cliitiiioiomis. - In the lower part of the A. den, to the first occurrence of Arigochitirin loiigicollis Eisenack lorigicollis Zone Aiicyrocliitirto sp. aff. aiicyrea A appears. 1959. Coriocliitirin eriintastensis Nestor 19820 and Coriocliitirin

280

GFF 120 (1998)

Grnhri: Lower Siliirinn Cliifiriozonarid biostrntigrcipliy of the rrinirilnrid of Sweden ROSTANGA

SODRA SANDBY DRILLING 27

SMEDSBY GARD DRILLING 1

4

Covered 40.00 m

C. rigidus Zone

M. crispus Zone

_ _ _ -

v;4


ro

S. turriculatus Zone

---S. sedgwickii Zone

--_P. acurninalus Zonc

Fig. 12. Lithology and sample levels in RostSnga 4, Skilne. Legend in Fig. 3.

_---N. persculptus Zonc

yrneproboscifern Nestor 1994 disappear within the C. lapworthi Zone. In the 0. spirnlis Zone Roiiiochitirin iicstoroe (Grahn 1995), Cuiiocliitiiin proboscifern grncilis Laufeld 1974, Coriochitirinproboscifern triiricntn Laufeld 1974, Coriochitirin ocioiiirintn Eisenack 1959, C. visbyerisis Laufeld 1974, Desniochitirin derisn Eisenack 1962, Rmnocliitina rzihiiiieiisis (Nestor 19826), hfnrgachitina riinrgnrilnrin (Eisenack 1937), Plectochitirin pnchyr(Er7ria (Laufeld 1974) and others occur for the first time. occiirreiices oictside Swedeti. Angochifirin lorigicollis is also known in Estonia and north Latvia (Nestor 1984, 1994), Bohemia (Verniers et al. 1995), Welsh Borderland (Doming 1981; Mabillard & Aldridge 1985), Brabant Massif (Verniers 1982). Condroz Ridge (Verniers et al. 1995), Canada, Quebec, Gasp6 Peninsula (Achab 198l), Ohio, USA (Grahn 1985), south China (Geng et al. 1987). Kilowit

- -

I

0 1

Fig, 13. Lithology and sample levels in Smedsby GSrd drilling 1, Ostergotland. Legend in Fig. 3.

2 3rn

lorigicollis by Verniers et al. (1995) is defined from level 155 ni in the Rosendal drilling 1, Gotland, which corresponds to the 0. spirnlis Zone (Grahn 1995), to the first occurrence of hfnrgncliifinnirinrgnritnrin in the Leasows section, Welsh Borderland (Mabillard & Aldridge 1985).

Raniochitiria iiestorae Subzone De/initiori. -This subzone corresponds to an interval from the first occurrence of R. iiestorne Grahn 1995 in Sweden, to the top of the C. cerztrijiigiis Zone. It is also the total range of R. nesforne.

Renirirks. - The A. loiigicollis Zone in Sweden corresponds to an interval from Type irifenalnrid locality. -The holotype Nestor the base of the S. tttrriciilatrtsZonc to the (G~t~niz~oclziriizniiirrgtiificn top of the C. riiirrcliisorii Zone. Nestor 1982b, redefined because of junior syn(1994) defined the A. lorigicollis Zone as onymy into Rarriochifirin riestoroe Gralin an interval zone corresponding to the S. 1995) was described from the Riga Fortirrriciilitirs, M. c r i s p s and parts of the mation, Jaani Stage (Upper Llandoverynf. griestorrietisis zones. The Zone of A. Lower Wenlock), in the Ruhnu drilling

Fig. 14. Lithology and saniple levels in S d r a Sandby drilling 27, SkBne. Graptolite biozonation after Nilsson (1979). Legend in Fig. 3.

(454 m), Ruhnu, south Estonia. As the type interval for the R. riestortle Subzone, the Lower Visby Beds on Gotland, Sweden (Grahn 1995), is suggested. No type locality is assigned. Clinriicteristic chitiiiozonns. - Besides R. ncstorne, the same chitinozoan species are present as in the upper part of the Aitgocliitirin loiigicollis Zone. Krioivri occiirreiices oiitside S\vedeii. Raniocliitirin iiestorne is also described from Estonia and north Latvia (Nestor 19828, 1993).

GFF 120 (1998)

Grnhn: Lower Siliiriari Cliitiriozoa arid biostrnfigrapliy of tlie ninirilnnd of Sweden

28 1

SER.

A

A I I

Y

0

sz

W

s


-

>

@

8 z 4

_1

Fig. 15.Correlation table for the mainland of Sweden, and the stratigraphical ranges of the chitinozoan species (see also Grahn 1996 for the included Upper Wenlock chitinozoan species). Graptolite zonation after Jaeger (1991).

Ei'itconochitiiraprrteclnviforiirisZone

scribed as C. clnvifoniiis by Nestor (1994). are here considered as E. prneclrivifonnis.

Dejiriitiorr. - This zone corresponds to the partial range of E. prneclavifonnis nsp., from its first occurrence in Sweden, to the first occurrence of Cirigiilochifirin cirzgiilntn (Eisenack 1937) and Ancyrochifirin giitriicn Laufeld 1974.

Ciitgi~locliitirincingidatn Zone

Tjpe i n t e n d arid locnlity. - As the type interval for the E. pmeclnvi~onnis Zone, the Cyrtograptus ShaIe and lower Colonus Shale, from the first occurrence of E. prneclaviforrnis to the first occurrence of Cirzgiilochitirin cirzgiilatn and Ancjrochifirici giitriica in Skine, Sweden, are suggested. No type locality is assigned. Cliarncteristic cliifiriozonns. - On Gotland Corrochifirin leptodoes not reach as high as the Slite Beds, but in Estonia and north Latvia the species occurs up to the first occurrence of C. cirigiilntn and A. giitriica (Nestor 1994). Cirigiilocliitiria sp. 1 is restricted to the lower part of the zone. Coriochitirinf7nrrirrin Laufeld 1974, C. ninmilln Laufeld 1974 and Koniocliitiria conziciilnfa (Laufeld 1974) have their ranges within the zone. Coriocliitirza visbjensis Laufeld 1974 and Desiriochifirin delerun Eisenack 1962 disappear in the lower part of the zone, and in the upper part disappear Cnlpicliitirra opacri (Laufeld 1974) and Plectochitiria priclrjrlenrin (Laufeld 1974). Cnlpicliifirin acollnris (Eisenack 1959) occurs in the upper part. soilia

Kriowi occiirrericesoiitsirle Sivederi. - Eiiconochitina praeclavifonizis is also described from Estonia and north Latvia (cf, Nestor 1994).

Keninrks. -The E. prneclnviforrriis Zone corresponds to an interval from the base of the Af. riccnrtonensis Zone to the upper part of the AT. beloplionis Zone. Specimens without mucron, de-

Defiliifiori. - This zone corresponds to an interval from the first occurrence of C. cirigirlorn (Eisenack 1937) in Sweden, to the first occurrence of Sphrrerochifirinljcoperdoides Laufeld 1974. Tjpe i n t e n d arid locnlity. -The holotype of the zonal index species was described from an erratic of unknown age and provenance. As the type interval for the C. cirigiilata Zone in Sweden, the Slite Beds unit f to the first occurrence of Splinerochifirin ljcoperdoirles in the upper part of the Mulde Beds (Middle Wenlock), is suggested. No type locality is assigned. CIInrncteristic clzitiiiozoaris. - At the base of the C. cirigiilntn Zone, Lirzocliitirin odiosa Laufeld 1974, Ancyrochitirin giitriica Laufeld 1974, Coriochifirinfiiba Eisenack 1932, and C. pachycephnla Eisenack 1964 appear for the first time. In the upper part of the zone there are rare specimens of Liriochifirin erratico (Eisenack 1931). Krio~vriocciirrerices oiitside Sivederi. - Cirigiilocliitirin cirigiilata is reported from Estonia and north Latvia (Nestor 1994), Poland (Rombouts 1982), Ukraine, Podolia (Tsegelnjuk 1982), Wales and the Welsh Borderland (Aldridge et al. 1979; Doming 1981; Swire 1993), the Brabant Massif, Mehaigne area (Verniers 1982), southwest Southern Uplands (White et al. 1991), Bohemia (Dufka iri Kriz et al. 1993), and Libya and Algeria (Verniers et al. 1995). Remarks. - The C. cirigirlntn Zone corresponds to an interval from the upper part of the M. beloplionis Zone to the upper part


282

Grnhti: h i r e r Siliiriori Cliitiiiozon nrid biostrntigrnpliy of the iiiaitilmirl of Slvedeii

GFF I 2 0 (1 99s)

Fig. 16. Selected Chitinozoa from the Early Silurian of the mainland of Sweden. A. Desrrzochitirrn sp.. RM Ch 127. Nederberga 1, sample 19.5. C. lopwortlii Zone? SEhlx375. B. Citlgll~~chi~iflfl Sp. 1, Rhl Ch 128. Rostdnga 5, +0.5 m. ht. riccnrtotietisis Zone. SEM ~ 1 2 0C. . Eiicoriocliititioproeclnrifbnrris nsp. Holotype. Note the smooth base. RM Ch 129. RostSnga 5, +0.5 m.ht. riccnrtorzerisis Zone. SEM x65. D. Gicotrocliitirrn prneclovifoniiis n.sp. Paratype. Rhl Ch 130. Rosthga 3, +1.00 m. C. rigidris Zone. SEhI ~ 8 0E. . Ancjroclritirin sp. aff. nrlcjren A., RM Ch 13 1. Osmundsberget 1, -3.10 m. S. tiirriciilntiis Zone. SEM ~ 2 2 0F. . Cjothochitinn sp. aff. cnrtz~~nrriilneforrtiis, Rhl Ch 132. Lovisefred drilling 1,299.00 m. C. gregnriirs Zone. SEM x145. G. Corrochilirzn olorgndo (Cramer 1967). Rhl Ch 133. Kallholn 1, -18.80 m. C. gregnriris Zone (hi. nrgeriteirs Subzone). SEhq ~ 2 0 0€I. . Eircotzochirbro proeclnvifonriis nsp. Rhl Ch 134. Specimen with flattened basal part. RostSnga 4,base. C. rigidis Zone. SEM ~ 1 3 0I.. Rnriiochitirio irestoroe Grahn 1995. Rhl Ch 135. Kallholn 1, -8.90 m. 0. spirdis Zone. SEM ~ 1 5 0 .

of the P. dirbiiis-G. tinsso interregnum. Nestor (1994) defined a C. citigirlnta interval Zone corresponding to the Middle part of the Slite Beds unit g on Gotland. Verniers et al. (1995) defined the C. ciiigirfntci Zone in a roughly equivalent interval. Aricjrocliitiria girtriica Subzone Dejitiitinii. - This subzone corresponds to an interval from the first occurrence ofA. girftiicn Laufeld 1974 in Sweden, to the top of the C. Iirdeiisis-C. gerliortli Zone. Type i n t e n d mid locality. - The holotype of the index species was described from the Slite Marl on Gotland in strata sIightly younger than the Cotichirlirrtii teiiiristricifirtti Beds. The type locality is Valbytte 1 (Laufeld 1974). As type interval for the A. girttiica Subzone, the Slite Beds unit c to the base of the H e m e Beds on Gotland (Grahn 1995), are suggested. No type locality is assigned. Clinrocterisfic cliititiozontis. - Litiochi~itinodiosn Laufeld 1974 disappears, and Litiochititin n.sp. aff. L. errntica Laufeld 1975 occurs in the C. pmederibeli Zone. The latter chitinozoan species is seemingly restricted to the A. girftiicn Subzone. The first occurrences of Kariiochititin tabeninciilifern (Laufeld 1974). R. irricirintn (Laufeld I974), R. \wlbyttieiisis (Laufeld 1974). and Splinerocliitiiin diibin Eisenack 1968 are in the upper part of this subzone. On Gotland, CIn/hrochitirin clnthrntn Eisenack 1959, Cotiochifitincirgillopliiln Laufeld 1974, C. giittn Laufeld 1974, Cdpichititin open Laufeld 1974, Rmriochititia itiartirissorii (Laufeld 1974), and R. spiizosa (Eisenack 1932) occur in the lower part of the subzone. Ktio,vii

occirrretices oiitsidc S\redcti. - Aricyrochitinn guttiica is

also known from Estonia and north Latvia (Nestor 1994) and Shropshire (Doming 1981). Retiiarks. - The A. giittiictr Subzone corresponds to an interval from the upper part of the M.beloplrorirs Zone to the top of the C. lirdetisis-C. gerlinrdi Zone. The Splinerochititin Iycopcr-doidesZone and younger Silurian chitinozoan zones were defined by Grahn (1996).

Concluding remarks Chitinozoans from the Lower Silurian of the mainland of Sweden are less diverse than the chitinozoan assemblages from the same age recently described from Gotland (Laufeld 1974; Grahn 1995),Estonia and north Latvia (Nestor 1994).Nestor (1994) defined 22 biozones in the Lower Silurian of Estonia and north Latvia, and Verniers et al. (1995) defined ten zones in a global Silurian biozonation. In general, it is easy to compare the Swedish biozones with those defined by Nestor (1994) and Verniers et al. (1993, except for the Lower Llnndovery (Rhuddanian) where it is still problematic to correlate sequences between the different regions. Ach~owledgni~en~s. - I m indsbkd to Profeuon Jan Bsrphiirn and hkurilr Lindstriirn (Surkholm. Sivedun) for cummcnts and improvem-nLs of the r r m n u ~ p fand to Dr. h o r n Nilson (Lurid Sivedtn) for unpubli\hed i n f m h o n d m u l pplolilcs. A p.mt from t k Swedish h ' m d Science R-h Council (hTR G-IWGU 0581 1-311) nude thk \!'Ork possible.


GFF 120 (1998)

Grnlitr: Lower Silirrinri Clzitirzozon and biostratigrnpliy of !lie inniiilntid of Swedeli

distribution in the Silurian of Britain and Ireland. In A.L. Harris, C.H. Holland 8: B.E. Leake (eds.): ?7re Culrdonides of die Brirish Isles reriwd. 433438. Geologicul Socier?; of London. Sprciul Prrblicurion 8. Asselin, E.. Achab, A. 8: Bourque. PA.. 1989: Chitinozoaires du Silurien infirieur dms 13 rigion dc la Bait des Chaleurs en Gas#sie. Qur'bec. Cmada. Cunadiun Jorrrnul of Eurrlr Sciences 26.2135-2.119. Bassert. h1.G.. Cherns, L. 8: Karis. L.. 1982:The R a e Formation: early Old Red Sandbtonc facies in the Silurian of JBmrland. Sweden. Swriges Geologirku Undersiihing C 793. 121. Brrgrtrom. S.hl. R: Bergstrom. I.. 1996: The Ordo\ician-Silurian boundary successions in OstergBtland and Viistergotland. S. Sweden. GFF 118.2542. Bjerreskov. hl.. 1986: Silurian graptolites from deep well h l a g l q I. Scania. Sweden. Geologiskfl Foreningens i SrocXholm Forhnndlingnr 109. 1-12. Boucot, A.J. R: Johnson. J.G.. I9Gi: Brachiopals of the Ede Quartzite (Lower I.lando\ery) of Norderiin. Jimtlmd. Birllerin of the Geologicul Insrirrrrions of rlre Uniwrsir?; of Uppsulu 42. 1-1 I. Bulman. 0.hI.B.. 1932:On the graptolites prepared by Holm 2-5.Arkivfur Zoologi 24A 1015. Cherns. L. R: Karis, L.. 1995: Late Ordovician