Upper Triassic Involutinidae (Foraminifera) of Lime Peak in Yukon, Canada

Vol. 33, No. 1·4

ANDRZEJ GAZDZICKI & PAMELA REID

acla geologlea polonica Warszawa ·1983

Upper Triassic Involutinidae (Foraminifera) of Lime Peak in Yukon, Canada

ABSTRACT: Tethyan benthic foraminifera of the family Involutinidae Biitschli have been discovered in the Upper Triassic sequence at the Lime Peak, Yukon (North Western Cana,da). Five species belonging to the genera AuZotortus Weyn- schenk and Triasina Majzon are recognized. The presence of Triasina oberhauseri Koehn-Zan.i.netti & BTOrutiman:n in the involutinid a;ssemblage indicates a Norian

age for the investiga.ted strata.

INTRODUCTION

The majority of involutinid foraminifera occurring in the Late Triassic of the' Te'bhyan rea'lm are represented by <the genera: Aulotortus Weynschenk, Auloconus Piller, and Triasina Majzon (see Zaninetti 1976, PiiHer 1978, Gazdzick'i 1983). They have been used to el1ect local zonati'OlIl (Salaj 1969, 1977; Gaidzick.i 1974, 1983) and they may aJsobe of prime importance in regiona~ biostraJtigraphic co!l'relatiollLS and paleogeOigraphic reconstructions (Bronnimann, Whdrttaiker & Zan1netti 1975, Gazdzicki &

Smit 1977, Gazdzicki & Gupta 1981).

This paper records the discovery of invOIluif;inids Lrom the Late Tria'Ssic of North America.· The oocu:rrence of these involutiJnids, far distant from their counterparlts in 1lhe Te1Jhyan reailm, casts a new Ughlt on the paleoJbiogeograplric position of North WesteI'lIl America at the end of the 'Th-iassic (see also GaZdzicki & Sta.nley 1983).

The investigated involutinid forarminifera are in thin sectioms made frOim Lime Peak rooks (Texlt-fig. 1), and aI"e housed in the Im:titute of PaleobioJogy of the Pdlish Academy of Sciences, Warsaw, POIland (ahbre- via.ted as ZPAL).

Acknowledgements. The Authors thank Prof. Dr. E. Fliigel (paleontological Institute, Erlangen-Niimberg University) for inviting to the Ln,ter:national Sym- pooium on. Triassd.c Reefs ·(Erlangen, 1981) during which ideas discussed in this paper were conceived.

100 A. GA:2:DZICKII & P. REID

The Authors aTe also grateful to the Deutsehe Fors·chungsgemeinschaft for the generous support of scientific visit to West Germany and the Al,ps in 1981.

Finally, a fellowship granted by the Alexander von Humboldt Foundation (Bonn) to one <Y.f the Authors (A. Gazdzicki) has enabled detailed study and is hereby grateiully acknowledged.

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Fdtg. 1. Locaition of the study aJI'e-a

A - Location of the Yukon Territory and Lime Peak (arrowed) in the generalized map of. North AmeTica.; B - Lar,ge scale map of the Yukon Territory showing

position of Lime Peak and Whitehorse

GEOLOGICAL SETTING

The Canadian Cordillera lis divided into, five mructural and physio- graphic 'belts (Texit-fig. 2). The U!PIPer TrialSiSic carbonate fades in whicih involutinid foraminifera were found, occur ⁱⁿ the Intermontane belt Oif, the Yukon Territory (i.e., the WhWtehOll'Se Trough). The genera~ geo1logy of the Whitehorse Trough was described by Tempelman-Kluit (1978, 1979). It· was a Mesozoic basin in which were deposilted Upper Triassic and Lower Jurassic fanglornerate and flySdh I(derived from a volcano- plutonic are to the southwest} intercalated :with discontinuous lenticular carbonates. The prevalence of vo[cano-clastic sediments and the va:riruble nature of 'the carbonates reflect the tectonic instahility of this· area (Reid & Tempe1man-K[uit 1982).

The discontinuous lenticular shape of 1Jhe Uwer Triassic car.bonates in the Whttehorse Trough has been interpreted in two ways. Tozer (1958) and Wheeler (19161) proposed that the irregularities :were caused by erOlSiona!l unconionnities, but T€lffiIPe'lman-Kluirt (1979) suggested that the irregular carbonates are tfhe reefs (see also Reid 1981, Stanley 1982).

UPPER TRIASSIC INVOLUTINIDAE 101

Lime Peak is located near Ithe soiUtheastern end of Lake LaBe!l"ge, apjproximately 40 km norlheaSlt of Wihiteihocse (Text-fig. 1), The mountain extends northeast-southwest ~ongThomas Lake about 3.5 km and north of the lake a'OOut 3 ~ {Text-fig. t and Bl. 1, Figs 1--<2).

FACIES UNITS AND DISTRIBUTION OF FORAMINIFERA

The Lime Peak carbonates are weH.-exposed and they sihOlW multi.p~e

stages of reef growth and a completefacies zonation from massive reefal limestone toofflapping sIlope and basina,l sedimenta (P1.1, Figs 1-2).

Fig. 2

Map of the Canadian Cordillera showing the five structural and physio'gra'Phic belts and Stikine terrane(a!ter Monger & Price,

1979)

~STII(INE

l:.;;J TEllAANE

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The reefoid SJtruoture of Lime' Peak is divided into a few facies uniJts whioh intedinger each other (Text-fig. 3). FouI'l main roC'ks types ,were recogniz:ed in the fieiJ.d: ma'SSi'Ve lightgrey-hrown limestone, bedded limestone, dark shaley limestone, and limestone tbreocia (see Reid 1981).

The involutinid foraminifera (see Text-filg. 3 and Pl. 1, Figs l-a) were found in the' malSsi'Ve reefallimeSltones I(sample: LPU-l) and bedded limestones (samples: LPL-9 and R-BO-21-6).

102 A. GAZDZICKIr & P. REID

The massive limestones varry bdth in thidkness and liJthology. Thick- ness varies from a' few meters to over 100 m; lithology Tang'es from peloidaJ. mudstones to organic framestones comaining ~omorphs,

ta!bulozoans and ca!l.caroous spolllges. Contributions from oorals, bracihio- pods, mOlluscs, afrgae, foraminirfera and echinoderms to the litholOlgy are 1€SS significant. Rare invOllutinid fOlramicifera are represented by Triasina oberhauseri (see PI. 3, Figs 1l...42). Other fomminiferal genera include Ophthalmidium ood Diplotremina. Skeieions and bioolaSlts are often encrusted and bound with da'rlk biogenic (allgllll?) coatings,and voids are commotrly lined with radial fi'brOlUS cements and subsequently fiUed with sediment. The massive limesitones are intel1Preted as reefal by Reid (1981).

The bedded limestone uniJt (Text-fig. 3 and PI. 1, Figs; 1----2) is an alternation of thick beds of reef-derived debris with thinner beds con- taining attached spongiOlIlloopihs, thick-shel1ed pe!l.ecy.pods, lar.ge gastro- pods and also sponge and corals which colonized the debris layers. In- volutinids are represented by co:mmon Aulotortus gaschei (see PI. 2, Figs 4---.7), a few Aulotortus tumidus (see Pl. 3, Fig:I 5-6, 7a) and Aulotortus sinuosus indtviduals and two forms possibly referable to

?Trocholina (see PI. 3, Fig. 7b)A Other forarminiferaoccumng with the involutinids are: Variostoma Bp. (common), and rare Duotaxis cf. bir- manica, Planiinvoluta carinata, Earlandia sp., Trochammina $p., Agatha- mmina sp., Ammobaculites sp., and nOldosarriids. This unilt is 1nter.preted as sh:>tpe dep0sirt5 by Reid (1981).

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.4 _{/ 5}

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lime Peak

Fig. 3. Distr~bution of main rock types on the southern slope of Lime Peak;

sampling site LPL-9 is indicated

1 - massive reefal limestone, 2 - bedded limestone (slope deposits), 3 - shaley limestone (hasmal sediments), " - limestone breccia, 5 - fault

ACTA GEOLOGICA POLONICA, VOL. 33 A. GA:2:nzIcKI & P. REID, PLo 1

· .W E

Lime Peak

1 _ Southern slope of Lime Peakj 2 - Aerial view of Lime Peak from the north- -west, both to show the sampling sites (LPL-9, LPU-l and R-SO-21-6) with involu-

tinid foraminifera

UPPER TRIASSIC INVOLUTINIDAE 103

INVOLUTINID ASSEMBLAGE AND I'.[1S AGE

The reefal and 'bedded limestcJnes of Lime Peak are cOlll!Posed mainly of spongiomonphs, talbulozoans, sponges arnd cora!ls. W,ithin assemblages formed by those organisms, locally the foraJIllinif.era of the family In- vOllutinidae ButscMi, 18'80, n'alve been also sigrnificant microfaurnal COIn-

ponoot af :the COimmunity.

Recognized assemblalge of the involwtinids from reefal limestone comprises:

Triasina oberhauseri Koehn-Zaninetti & BrOnnimarm., 1968 - PI. 3, Figs 1-2

?Triasina sp. - PI. 3, Figs 3--4

Involutinid assemblage from bedded limestone comprises:

Aulotortus gaschei (Koohn-Zaninetti & BrOnnimann, 1968) - PI. 2, Figs 4-7 Aulotortus sinuosus Weynschenk, 1956 - PI. 2, Fig. 9

Aulotortus cl. sinuosus Weynschenk, 1956 - PI. 2, Fig. 8

Aulotortus tumidus (KrisUln-Tollmann, 1964) - PI. 3, Figs 5-6, 7a Aulotortus sp. - ·PI; 2, Figs 1-3 and PI. 3, Fig. 8

?Trocholina sp. - PI. 3, Fig. 7b

In 1lhe above assemblages the ~ecies Aulotortus gaschei is dominant, whilst A. sinuosus, A. tumidus and Triasina oberhauseri are represented by a few specimens only. The bedded limestone is distinctly richer than the reefaJl limestone in species variety and total number of individuals.

The state of preservation af the invrouflinid tests is generSJIly satis- fa.ctory aIlthough a mOlI'e or less advaJllced spa'ritizaltion makes difficult recognition of the deltailed structure of some specimens (see PI. 3, Figs 1---4). '!be method presented by Delgado (1977) proved very use:ful during the C'lJ(['II"eIl1) study for rthe recognition of the . internal struclure orf 1lhe involrUJtinid test inrtihin sections. It made it possible to see under- developed segmentation of deuteroloculus in the strongly recrystallized Triasina oberhauserispecimens (Pl. 3, Figs 1~2).

The identified inv,dlutinid assemblages permit ass1gnment of the investigated straUi. to the Norian. This age is particularly indicated by the presence of Triasina oberhauseri, an index fossil of the oberhauseri Partiail-range-zone '(GaZdzioki 1983).

The studied N oriarn. a.nvolutilnrl.d foraminifera of Lime P.eak are similar to the contemporanous assemblages from the Tethyan realm (cf. Za- ninet'ti 1976, Pi1:ler 1978, Ga.2ld·zicki 1983) a'lthough they are impoverished in number of species as well indiJviduals.

PALEOGEOGRAPHIC REMARKS

The Upper Triassic involutinid foraminifera are geographkally ex- tenSive i:n their distrilbution. They halVe been recorded from shallow waiter carbonates of the Tethyan realm from the Rif MtsI in Morroco through the Alps and Himalayas to the Calamian Islands and Papua

104 A. GAZDZICKlt " P . REID

New Guinea (see GaZdzicki 1983). The OC'C'llrrence of UplPer Triassic InvolUItinidae in the cartbonate sequence of Lime Peak extends their known geographic railllge. However, it is difficult to e~iain tlheiroccur- rence in ,rthe area located so far from the Tethyan region.

New concepts O'n microplates and d~laced teIU"alIleS in Western North America suggest that much, if not all of the Cordilleran region is allochthonous wirtih reaped to the NO'rth American cratOlIl (lrving 1979;

Beck, Cox & Jones i980; Monge!r & lrving 1980). It is quite probahle that some of these mic:roplates originated closer to' the Tethyan re'gion (see also Gaidziclki & Stan!ley 1983). The striking similarity between the Upper Triassic cwbonate fa'cies' and involutinid assemblages OIfLime Peak and those oftlhe Tetlhyan "realm (Fliige<l 1981, 1982; Stanley 1982) tends to support thealloohthonous concept models.

Institute of Paleobiology of the Polish Academy Of Sciences,

Al. Zwirki i Wigury 93, 02-089 Warszawa, Poland

(A. GaZd2lioki)

REFERENCES

Rosenstiel School of Marine and Atmospheric Science,

University of Miami, Fisher Island Station, Miami Beach, Florida 33139, U.S.A.

(P~ Reid)

BECK M., COX A. & JONES D. L. 1980. Mesmoic and Cenozodc microplate tectonics of western North America: (Penrose Conference Report). Geology, 8, 454--456.

Boulder, Coiorado.

DELGAI)O F. 1977. Primary textures in dolostouesand rec~ystallized limesto(nes:

a technique for their microscopic study. J. Sedim. Petrot., 47 (3), 1339-i341.

Menasha, Wisconsm.

FL'OGEL E. 1981. Paleoecology andfacies of Upper Triassic reefs in the Northei'in Calcareous Alps. In: TOOMEY D. F. (Ed.), European fossil reef models (Soc.

Econ. PaZeont. Miner. Special Publication, no. 30), 291-359. Tulsa, Oklahoma.

- 1982. Evolution of Triassic reefs: cUrrent concepts and problems. Facies, 6, 297-327. Erlangen.

GAZDZICKI A. 1974. Rhaetian microfacies, stratigraphy and fades development in the Tatra Mts. Acta GeoZ. Polon., 24 (1), 17-96. Warszawa. .

1983. Foraminifers and biostratigraphy of the Upper TciaS'sic and Lower.

Jurassic of the Slova'kian and Polish Cal'pathians. Palaeont. Po Ion., 44,. 109-

169. warszawa-Krak6w. .

& GUPTA V. J. 1981. Triassic fOTaminifers involut:i!ni<iae from the· West Carpathians and Himalayas - its· stratigraphic and palaeobiogeographic implications. Bull. Ind.Geol. Assoc., 14 (2), 101-106. Chanddgarh. .

& SMIT O. E. 1977. Triassic foraminifers frOlIIl the Malay Peninsula. Acta Geol. Polon., 27(3), 319-332. Warszawa.

& S,TANLEY G. D. Ji. 1983~ Fu-st report of Involutinidae (Foraminifera) in

mariine Triassic rocks of North America. N. Jb. Geol. PaUiont. Mh., 2, 80-90.

Stuttgart.

mVING E. 1979. Paleopoles and paleOilatitudes of Nocth America and speculations about ddsplaced terrains, Canad. J. Earth Sci., 16, 669-694. Ottawa.

MONGER J. W. H . .& IRVING E .. 1980. Northward displacement of northcentral British Columbia. NtituTe, 285(5763), 289-294. London.

UPPER TRIASBle INVOLUTINIDAE 105

& PRICE R. A. 1979.· Geodynamic evolution of Canadian Cordillera - progress and problems. Canad. J. Earth Sei., 16, 771-791. Ottawa.

PILLER W. 1978. Involutinacea (Foraminifera) der Trias und des Lias. Beitr.

Paliiont. Osterreieh, 5 (1), 1-164. Wien.

REID P. 1981. Lime Peak: a well-developed Uwer, Triassre Ireef complex in Northern Canada. Abstracts of papers; International Symp. on Triassie Reefs, Erlangen, 41)-46. Erlangen.

& TEMPELMAN-KLUIT D. 1982. An association of reefal carbotnates aItld

volcano-clastics in the Upper Trilassic of the Y1.ljlron Territory, Canada.

Abstracts of papers;. Eleven International Congres on Sedimentology, Ha- milton, Ontario, Canada, p. 110, Hamilton.

SALAJ J. 1969. Essai de zonations dans le Trias des Carpathes Occidentales d'apres les Foraminiferes. Geol. Prace, Sprdvy, 48, 123-128 .. Bratislava.

- 1977. Contribution it la micrOlbiostratigraphie du Trias des Cail'pathes Occiden- tales tchecoslovaques. Aetes du VIe Colloque Afrieain de Mieropaleont.

Tunis 1974, Ann. des Mines et de la Geol., 28, 103-127. Tunis.

STANLEY G. D. Jr. 1982. Triassic carbonate development and ;reef-building in Western North America. Geol. Rundsehau, 71 (3), 1057-1075. Stuttgart.

TEMPELMAN-KLUIT D. J. 1978. Reconnaissance geology, LalBerge map area, Yukon. Current Research, part A. Geol. Survey of Canada, Paper 78-1A, 61-66. Ottawa.

- 1979. Transported cataclasite, ophiolite and granodiorUe in Yukon: evidEmce of arc-continent collision. Geol. Survey of Canada, Paper 79-14, 1-27. Ottawa.

TOZER E. T. 1958. Stratigraphy of the. Lewes River. Group (Triassic), central LaBerge area, Yukon Territory. Geol. Survey of Canada, Bull., 43, 1-28.

Ottawa.

WHEELER J. O. 1961. Whitehol1"se map-area, Yukon Territory. Geol. Survey of Canada, Memoir, 312, 1-156. Ottawa'.

ZANINETTI L. 1976. Les Foraminiferes du ~s. Essai de synthese et correlation entre les domaines mesogeens europeen et asIatique. Riv. Ital. Paleont., 82 (1), 1-257. Milano.

106 ^A. GAŹDZICKlI & P. REID

A. GAŹDZICKI i P. REID

OTWORNICE INVOLUTINIDAE Z GORNOTRIASOWEJ SEKWENCn LIME PEAK W KANADZm

(Streszcrenie)

W rafowych utworach górnego tria'Su Lime Peak (Terytorium Jukon) w Kana- dzie znaleziono tetydzkie otwornice bento.niezne z irodziny Involutinidae Biitschli (patrz fig. 1-3 ocaz pl. l). Rozpoznano między innymi (patrz pl. 2-3): Triasina oberhauseri Koehini-ZanJiJnettd & BrOiIllniman.n, AuŁotortus gaschei (Koehn-Za:ndInetti

& BronnimalIlll), A. sin'UCsus Weynsehenk oraz A. tumidus (Knstan-Tollmann).

Obecność w tym zespoIe gatunku Triasina oberhauseri - taksonu wskaźnikowego

dla poziorriu ścieśnionego oberhauseri - dokumentuje norycki wiek rOZipatrywa- nyx:h osadów (por. Gaździoki 1983). Stwierdzenie obecności triasowych inwoIwtin z dala od ich rodzimej, tetydzkiej prowIDcji rzuca z kolei nawe światło na paleo-

geograficzną pozycję Ameryki Północno-Zachodniej u schyłku triasu.

ACTA GEOLOGICA POLONlCA, VOL. 33 A. GAZDZICKI & P. REID, PLo 2

orian Involutirnidae of Lime Peak 1 - Autotortus sp.; axial section (ZPAL F./R-3C1-21-6), X 150 2 - Aulotortus sp.; subaxial section (ZP AL F.!LPL-9), X 140 3 - AuJotortus sp.; axial section (ZPAL F./R-30-21-6), X 150

4- 7 - Autotortus gasche'i lKoehn-Zal ilP Lti & Briinllimann): 4 -- axial, 5-6 sub- axial, 7 - subequatorial section (ZPAL F./R-SO-21-6), X14.0

8 - AuLotortu.~ cf. sinuosus Weynschenk; ~ub~quatol'jal section (ZPAL F./R-80-21-G), X140

- AuLotortus sinuosus Weynschenk; axial section (ZPAL F./R-80-21-6), X130

ACTA GEOLOGICA POLONICA, VOL. 33 A. GAZDZICKI & P. REID, PLo 3

Norian Involutinidae of Lime Peak

1--2 - Tnasina oberhal1seri Koehn-Zaninetti & BrOnniman.n: 1 - axial sectio.n, X75; 2 - subaxial sectioll, )-,60 (ZPAL F.iLPU-l)

3-4 - ?Triasina sp.: 3 - equatorial. 4 -- oblique section (ZPAL F,/LPU-l), X60 5- 6 - Auloiortus tl1mid.us (Kristan-Toillllann); ;) - axial, t:i oblique section

(ZPAL F./LPL-9), v 140

7a - Al1lot07·tu3 tumidus (Kristan-Tollmann), ublique section, 7b - ?Trocholina sp., axial section (ZPAL F'/LFL-D), .X: HO

8 - AuLotortus sp.; equatorial section (ZP1-\L F'/LPL-9), X 140