Upper Ordovician brachiopods from the Anderken Formation, Kazakhstan: their ecology and systematics

67 Pages·2002·34.2 MB·English

by  L E Popov

Bull.nat.Hist.Mus.Lond. (Geol.)58(1): 13-79 Issued27June2002
Upper Ordovician brachiopods from the
Anderken Formation, Kazakhstan: their
ecology and systematics
POPOV
L.E.
DepartmentofGeology, NationalMuseumofWales, CardiffCF103NP
L.R.M. COCKS
DepartmentofPalaeontology, TheNaturalHistoryMuseum, CromwellRoad, LondonSW75BD
NIKITIN
I.F.
InstituteofGeologicalSciences,Almaty480100, Kazakhstan
CONTENTS
Synopsis 13
Introduction 13
Outlineofgeologyandfossillocalities 14
FaunalAssociations 22
Overallpalaeoecology 26
Systematicpalaeontology 27
Linguloidea 28
Discinoidea 28
Siphonotretoidea 30
Craniopsoidea 30
Strophomenoidea 30
Plectambonitoidea 38
Chilidiopsoidea 53
Triplesioidea 53
Protorthoidea 58
Orthoidea 58
Plectorthoidea 61
Enteletoidea 64
Camarelloidea 64
Rhynchotrematoidea 74
Lissatrypoidea 76
Meristelloidea 76
Acknowledgments 77
References 77
SYNOPSIS. ThebrachiopodfaunafromtheAnderkenFormation(LowertoMiddleCaradoc)oftheChu-IliRange,south-eastern
Kazakhstan, is revised and described systematically. It consists of62 species in 55 genera, ofwhich the genera Tesikella,
OlgambonitesandZhilgyzambonites(allPlectambonitoidea)andllistrophina(Camarelloidea)arenew,andthespeciesBellimurina
(Bellimurina)sarytumensis,Teratelasmellachugaevae,Foliomenaprisca,Acculinakulanketpesica,Dulankarellalarga,Kajnaria
rugosa,Anoptambonitesconvexus,Olgambonitesinsolita,Zhilgyzambonitesextenuata,Gacellainstitata,Placotriplesiaspissa,
Grammopleciawrighti,Dolerorthispristiua,Austinellasarybulakensis,Plectorthis?burultasica,Bowanorthis?devexa,Pionodema
opima,Parastrophinailiana,llistrophinatesikensis,Liostrophiapravula,Plectosyntrophiaunicostata,Rhynchotremaakchokense
andNikolaispiraguttulaarenew.Sixbrachiopod-dominatedassemblagesarerecognisedanddefined,termedtheEctenoglossa,
Tesikella,Mabe/Ia-Sowerbyella,Acculina-Dulankarella,Parastrophina-KellerellaandZhilgyzambonites-FoliomenaAssocia-
tions.Therelationshipswithcontemporaryfaunasareassessed,andtheAnderkenbrachiopodsappeartohavemuchincommon
withthoseofnorth-westChina.
INTRODUCTION _ _ separatecrustalfragmentsofvariablesize.Therelativepositionsof
these fragments are contentious; some authors, notably Sengor &
Natalin (1996), consider that most of the fragments made up an
TheglobalgeographyoftheLowerPalaeozoichasbeenthesubject enormousislandarc.termedtheKipchakArc,which stretchedina
ofwidespreadinternationaldiscussioninrecentyears(referencesin longcurvealltheway from the substantialcraton ofBalticatothe
Cocks2001),butmuchisnotyetclear. IntheOrdovician,thelarge central SiberianAngaran craton. Others, forexample Nikitin, have
area of what is today Kazakhstan was then divided into many subdivided Kazakhstan in other ways, with a more conservative
©TheNaturalHistoryMuseum,2002
14 L.E.POPOV,L.R.M.COCKSANDI.F.NIKITIN
Fig.1 GeneralisedmapoftheChu-IliRangeandWestBalkhashRegion(includingthesouthernpartofLakeBalkhash),showingtheboundariesofthe
EarlyPalaeozoictectonofaciesbelts,mainlyafterNikitinetal.(1991),andthepositionofthebrachiopodlocalitiesdiscussedinthetext: 1,Anderkenyn-
Akchoku;2,Kujandysai;3,eastsideofKopalysaiRiver;4,Buldubai-AkchokuMountain;5,TesikRiver;6,BurultasValley;7,south-eastsideofKaratal
RivernearSorbulakspring;8,7kmsouthwestofKarpkudukWell,KotnakMountains.
palaeogeography. Up until now, little assessment of the faunas OUTLINE OF GEOLOGYAND FOSSIL
containedwithinthesetectonicplateshasbeenmade,particularlyin LOCALITIES
relationship to contemporary faunas from other areas. One such
plateisthatformingtheChu-IliRange,andtermedheretheChu-Ili
Plate (Fig. 1). Within the Chu-Ili Plate the successions have been TheChu-IliPlate(Fig. 1),asrecognisedhere,isasmallpartofAsia
knownforsometime(e.g. Nikitin 1972, 1973). However,although today, and is traceable from the Zailiyskiy Alatau Range in the
anumberofpapershavebeenpublishedon aspectsofsome ofthe southeast to the northern Betpak-Dala Desert in the northwest,
contained Ordovician faunas, much remains to be done. A central where itdisappears underlate Palaeozoic and Mezo-Cenozoic de-
formationwithintheunitistheAnderkenFormationofearlyCaradoc posits.TothesouthwestitisborderedbythelargeDzhalair-Najman
age. This immediately underlies the Dulankara Formation, whose Fault and northward-dipping homoclinal sequences of Upper
brachiopodsfromitslowestOtarMemberwehaverecentlyrevised Cambrian and Lowerto Middle Ordovician age which are mainly
(Popovetal.2000).Althoughsomepioneeringdescriptionsofsome siliciclasticsloperisedeposits(e.g.theDzhambulFormation),indi-
of the Anderken brachiopods were published by Rukavishnikova cating passive margin development, and several thrust sheets
(1956)andsomeindividualspecieshavebeenpublishedinanumber consisting of dismembered ophiolites of the early Palaeozoic
of publications, e.g. Popov (1980, 1985) and Nikitin & Popov Ashchisu Formation (Toporovaetal. 1971).The Dzhalair-Najman
(1983), the whole brachiopod faunafrom the formation has never FaultmainlyfollowsanearlyPalaeozoicsuturewhichseparatesthe
beenpublished,andthisisthechiefpurposeofthepresentpaper.In LowerPalaeozoicChu-IliPlatefromtheMiddletoUpperOrdovician
addition, six brachiopod-dominated associations can be identified volcanic island-arc association traceable along the northeastern
fromtheAnderkenFormation. LEPandLRMCareresponsiblefor margin ofthe Betpak-Dala-North Tien Shan tectonofacies belt of
thewholepaperandIFNforinputintothesystematicpalaeontology Nikitin (Nikitin etal.1991), which is the same as the Djezkazaan-
andbiofaciessections. Kirgiz (4.1) tectonofacies unitofSengor& Natalin (1996). Tothe
UPPERORDOVICIANBRACHIOPODSFROMKAZAKHSTAN 15
Chu-lli Plate Burultastectonofaciesbelt
Zhalair-Najman Synclinorium Assemblageof Subduction-accretioncomplex
Centralpari Southernpart fo(onSrlaear-pyatracusmsbaaesZmiobnnleaa)ngde Bo(pudhrilusoblmaleittmeab)lerPeadckagedM(esalpiookpsueil-trsPi)ascekege oZ(phdhatllsoglmyletzmeb)Pearcekdege D(caarrbbaoznaatPeacplkaetgfeorm)
Zhalalr ZhalairFormation
Formation (siiistonea>ndmudstone,interlayersoflimestoneandtuff)
Chokpar CFohromkaptairon ULlikmuensttaosne (siClthsotoknpeaarndFmourdmsattoinoen,bla
KyzylsaiFormation
KFyozrymlastaiion a(snadndsislttosnteo,ne)polymlct
DulankaraFormation
(conglomeratepolymict,sandstone,siltstone,lensesoflimestone)
Unnamedformationof
AnderkenFormation sandstoneandgraded
(conglomeratepofymlct.sandstone,siltstoneandlimestone) soillitssttoosnet.romwiethhorizon
atthebase
BaigaraFm. BekeFormation OisaksaulFormation
s(silalitnmsdetssottnoeon)nee,and a(snadnmdsutdosnteo,nesi,ltgsrtaodneed) s(iclotnsgtloonemearnadtel,imseasntdosnteo)ne, BFuorrumbaatiitoanl
Kopaly (KFsoaarnrmadtasattloinoen, Uml(iuszmaduensnsdttbsootunnoelen,,ae,kminastFiseolsrtrlsfamtlyoaoentrwesiaoonfnd FBoorlmgaotzihoan/ALliamkeusltone rc(habedlriatoc)lkaarinadnred
siltstone. deposits) (siliceousshales,black,
mudstone,and Dzhambul "Akzhal"Formation siliceous;extrusives
tuff) Formation c(loinmgelsotmoener,atbeedadnedd, amnadsstufffl,orwhydoelpiotsei-tdsa)cite.
Kogashik (sandstone, sandstoneatthebase) Maikul
quartzose, Formation
UAnktgauur smgiruladtdssettdoo)nneea,nd qs(iuslaatrnstdtzsootnsoeena.en,d Zhalgyz
mudstone, Formation
graded) (sandstone,
olcano-clasticand
siltstone,graded
blackshale,
basalticextrusives
andtuff) DarbazaFormation
(quartzes
limestone
dolomite)
PrecambHanbasement niDiroiii
Angular unconformity Discontinuity q Stratigraphiccontact
unknown
Fig.2 ChartshowingthecorrelationbetweentheLowerPalaeozoiclithostratigraphicunitsintheChu-lliPlateandtheBurultastectonofaciesbelt.
north-east ofthe Chu-lli Plate lies the Burultas tectonofacies belt Figs 3, 4). Here the Anderken Formation overlies, with a slight
(Fig. 2), whichrepresentsanaccretionarywedge suggestingactive angularunconformity,gradedsandstones,siltstonesandmudstones
margin development, island arc volcanism and subduction ofthe oftheBekeFormation,whichisLlandeilotoearlyCaradocinage,
oceanic crust under the Chu-lli Plate from the earlyArenig to the datedby numerousgraptolitesoftheHustedograptusteretiusculus
LlandeiloPygodusanserinus Biozone (Koren etal. 1993). By the and Nemagraptus gracilis Biozones (Tsai 1976). The Anderken
Caradoc, subduction and volcanism had ceased as a result ofthe comprises six lithostratigraphic units traceable up to 40 km along
docking of a small terrane or island arc, the Mynaral-South strike, overlain unconformably by Devonian deposits. These units
DzhungariatectonofaciesbeltofNikitinetal. (1991). are(inascendingorder):
TheOrdoviciandepositsinthecentralpartoftheChu-lliPlate,the
Dzhalair-NajmanSynclinorium,formanearlycontinuoussequence Unit1. Polymict,pebblyconglomerate,withsandymatrixandwith
ofsiliciclastic and carbonate rocks from Arenig to Ashgill in age somebedsofsandstoneandgritstone.Thicknessfrom45 mto 120
(Fig. 2), which are relatively unmetamorphosed and chiefly dip m,withmaximumvaluesintheAnderkenyn-Akchokusection.
gently tothe northeast. They are coveredconformably by Silurian
Unit2. Coarse- to medium-grained sandstone with subhorizontal
deposits (Nikitin etal. 1980) or unconformably by the Devonian.
stratificationalternatingwithabundantcross-beddedsets.Lensesof
TheOrdovicianstratigraphyandmajorlithostratigraphicunitswere
polymict,pebbly conglomeraterepresentshallowchannels formed
describedbyKeller(1956)andNikitin(1972). by tidal currents. Thickness varying from 52 m in the Kujandysai
TheLowertoMiddleCaradocdeposits,whicharethemainsource section in the west to 180 m in the Anderkenyn-Akchoku section
ofthebrachiopodsdescribedhere,aretermedtheAnderkenForma-
(Figs 3, 5). The upper part contains the lingulide Ectenoglossa
tion,whichisatransgressivesequenceofmainlysiliciclasticdeposits sorbulakensis,thetrilobite "Isotelus" romanovskyiWeberandgas-
ptaharttcroenptraeisnenvtairnigabmluyddemvoeulnodpesdolreanlsg-allikbeuicladr-buopnsat(eNiukniittisnienttahle.u1p9p7e4;r tArnodpeordkse(nSyanm-pAlkecsh8o1k3u0-s1e,ct7i6o1n2c)o.nTtahiensmiadcdalrebopnaratteofmuthde-umnoitunindtuhpe
1996). They are best developed in the following eight general to16mthickwithacorebuiltoflightgreymicriticlimestone.Onthe
localities(Figs 1,3):
flanksthereisbeddedbiomicritewiththebrachiopodsSkenidioides
Localites 1-2.Areabetween theAshchisu and sp., Christiania sp. and Kellerella misiusi, the trilobites
MesotaphraspisspinosusLisagor,Selenoharpessp.,Acrolichassp.
Sarybulak rivers.
EokosovopeltisromanovskyiandSphaerexochusaff.hisingeriWar-
Inthesouth-easternpartoftheChu-lliRangethebestsectionsofthe burg.Illaenussp. wasnotedfromabout 1.0-1.5 mbelowthetopof
Anderken Formation are located in a block with faulted margins the mud-mound in the easternpartofitsexposure (Sample 8226).
between the riversAshchisu and Sarybulak (Fig. 1, localities 1-2; Cystoidandcrinoidcolumnalsareabundant.
.
16 L.E.POPOV,L.R.M.COCKSANDI.F.NIKITIN
Anderkenyn-Akchoku
1.
section(west)
l-»- 2. Kujandysaisection
Devonian
4. Buidukbai-Akchoku 8.SKoWtonfakKamorupnktuadiunks
Mountain
Devonian
7. Southsideof
Karatal riversouth
ofSorbulakspring 300
F-1024b
T.A. ,
6. Burultas
valley
A.-D.A. ,oo 2
«F8-1180a41a
T.A.
50
T.A.
.-F-1018
e-F-1018a
F-1024 T.A.
Ect.A.
Conglomerateandsandstone,
intercalating
Intercalatingsandstone 7*TT71 Conglomerate,pebbly,
andsiltstonewithcoquina polymict
stormbeds
Limestoneandsiltstone BekeFormation
intercalating
Sandstone,siltstone
andmudstone,graded
Sandstone,bedded.
MIDDLEORDOVICIAN
Sandstone,cross-bedded UzunbulakFormation
Sandstone Siltstoneandmudstone
Fig.3 ColumnarsectionsthroughtheAnderkenFormationshowinginformalunits,stratigraphicpositionsofsamplesandbrachiopodassociations:Ect.A.-
EctenoglossaAssociation,T.A.,TesikellaAssociation,M.S.A..Mabella-SowerbyellaAssociation.A.-D.A.,Acculina-DulankaretlaAssociation,P.-K.A.,
Parastrophina-KellerellaAssociation,Z.-F.A.,Zhilgyzambonites-FoliomenaAssociation,G.-B.A,Gastropod-BivalvedMolluscsAssociation.The
numbersofthesectionsarethesameasthoseonFig. 1
Unit 3. Coarse- to medium- grained sandstone with mostly luscs in association with the brachiopod Tesikella necopina (Sam-
subhorizontalstratification,about40-62mthickintheAnderkenyn- ples8127-2b,8129,8133,8138).Theupperpartcontainsanabundant
Akchokusectionandupto97mthickintheKujandysaisection,with brachiopod fauna ofthe Sowerbyella-Mabella Association (Sam-
somestormbedsofcoquinasupto20cmthickwithconcentrations ples 100b, 7613. 8128a, 8128b, 8135, 8137) and the trilobites
ofgastropods and the disarticulated bivalved molluscs Edmondia DulanaspislaevisanderkensisChugaeva,Lonchodomastecturmasi
fecundaKhalfin,Ctenodontasp.andOrthonota'lsp.(Sample8130a). Weber,Pliomerinasp.,Remopleuridessp.,Styginellamacrophtalma
Gastropods, bivalved molluscs and the trilobite Eokosovopeltis Pribyl & Vanek, Bronteopsis extraordinarisChugaeva, the cystoid
romanovskyibecomeincreasinglyabundantintheflankdepositsin and crinoid columnals Clivosocystis clivosus, Digiticrinus levis
theupper20moftheunit(Samples8130,8134).IntheKujandysai Stukalina, OrdinaricrinuspunctatusStukalinaandCommunicrinus
sectionconcentrationsofbivalvedmolluscsoccurinthemiddlepart communisStukalinaandthestarfishStenasterobtusus(Forbes).
pinelamssaotcoizaotiaonn wciotlhumtnhealrsareClbirvaocshoicoypsotdisTecsilkievlolsausnecSotpukianlainaandatnhde Unit5. Limestones varying inthicknessfrom 8to98mforminga
chainofcarbonatebuild-upsbetweentheUzunbulakandtheAshchisu
OrdinacrinuspunctatusStukalina(Sample7611). rivers(Fig.3).Thecoresofthesebuild-upsrestonabedofnodular
Unit4. Medium-tofine-grainedsandstonereplacedgraduallyup- limestone from 2-10 m thick with abundant dasyclad algae
wards by siltstone with numerous trace fossils and symmetrical Cyclocrinites nikitini Gnilovskaya and Mastopora reticulata
ripplemarks.Thicknessvariesfrom22to80mintheAnderkenyn- Gnilovskaya(Nikitinetal. 1974).Abedofnodular,algallimestone
Akchoku sectionandis about28 min the Kujandysai section.The withdasycladalgaeisusuallypresentintheinterspacesbetweenthe
lower part contains local concentrations of the coalified plant carbonate build-ups and contains brachiopods of the Acculina-
AkdalaphytoncaradociSenkevich,andgastropodandbivalvedmol- Dulankarella Association (Samples 100, 8251. 85258), the rare
UPPERORDOVICIAN BRACHIOPODSFROMKAZAKHSTAN 17
MIDDLE-UPPERORDOVICIAN
AnderkenFormation
Conglomerateand
redsandstone Siltstoneand Sandstone
mudstone(Unit6) I | (Unit2-3)
Limestone Conglomerate,
(Unit5) polymict(Unit1)
Sandstoneand
siltstone(Unit4) BekeFormation
|:x::::::| SSmaaunndddssstttoooninee,,gsrialdtestdoneand
Fig.4 GeologicalmapshowingdistributionoftheMiddleandUpperOrdovicianrocksandthepositionsofmeasuredsectionsandfossillocalitiesthat
yieldedbrachiopodsintheareabetweentheUzunbulakandAshchisuRivers,south-easternChu-IliRange(afterNikitin 1972,modified).
tabulatecoralsLichenarialsp. andAmsassia sp., stromatoporoids, and coarse- to medium-grained sandstone up to 70 m thick with
and various trilobites and echinoderms. Locally between the bivalves, rare Ectenoglossa sorbidakensis (Sample 8223-1) and
KujandysaiandSarybulakrivers,andonbothsidesoftheAshchisu numerousplantremainsofAkdalaphytoncaradoci;(2)intercalating
Riverintheeasternpartofoutcroparea,carbonatebuild-upsdisap- fine-grained sandstone and siltstone about 15-20 m thick with
pearandtheunitcomprisesbeddedlimestonevaryingfrombiomicrite brachiopodsoftheTesikellaAssociation(Sample 127),thetrilobites
to biosparite intercalating with siltstone and mudstone, with DuhmaspislevisanderkensisandLonchodomastecturmasi;and(3)
brachiopodsoftheParastrophina-KellerellaAssociation(Tables4— mudstones with some siltstones andfine-grained sandstones about
5,Samples628,8223,8223a,8223b).Brachiopodsofthisassociation 70-80 m thick with abundant brachiopods of the Mabella-
alsooccurinpocketsofbioclasticlimestoneinthemud-moundcore SowerbyellaAssociation(Sample8228).Thedepositsoverlyingthe
andtheoverlyingbeddedlimestonetogetherwithlargesphericalor Anderken Formation are polymict pebbly conglomerates and
ellipsoidal ooids of radiaxial calcite up to 1 cm across (Samples sandstonesoftheDulankaraFormation.
2538,8217,8219,8256).
Locality 4. Buldukbai-Akchoku Mountain
Unit6. Siltstoneandmudstonewithupto6interlayersofbentonite
up to 0.3 m thick in the lower part, total about 50-60 m thick, On the west side ofthe River Kopalysai, theAnderken Formation
containingbrachiopods ofthe Zhilgyzambonites-Foliomena Asso- includes a large carbonate mud-mound which forms the top of
ciation (Samples 8231, 8251, 8255). Abundant trilobites are Buldukbai-Akchoku Mountain. The lowerpartofthe formation is
Gramilatagnostus granulatus Kolobova, Sphaeragnostus sp., exposedonthesouth-westernslopeofthemountain,northofaneast-
Microparia speciosa Hawle & Corda, Hammatocnemis sp.. westfault(Figs 1, 3,5-7). Itincludes,inascendingorder:
BCihrumgaanietveasaalnmdatiOevnasilsoc(eChpuhgaaleuvsa),spC.,yclaonpdyggeraspp.t,olCiytbeesleinwcelbuedrei Unit1. Medium-tofine-grainedsandstoneupto 120mthickwith
Ectenoglossasorbidakensis.
Dicranograptus nicholsoni, Diplograptus anderkenensis,
GlyptograptustrubinensisandPseudoclimacograptusscharenbergi, Unit2. Darkgreen,beddedsiltstones,about 14mthickwithafew
suggesting the Lower to Middle Caradoc Diplograptus midtidens layersoffinegrainedsandstone3-10cmthick,containingMabella
Biozone(Keller 1956). conferta and Shlyginiafragilisofthe Sowerbyella-Mabella Asso-
ciation.
Locality 3. Eastside ofKopalysai River Unit3. Siltstoneswithnodulesofalgallimestonegraduallychang-
FOonrmtahteioenastissaibdoeutof1t6h0emKotphailcyksaaindRirvesetrs (uFnicg.onf1)ortmhaeblAyndoenrktehne tionpg,i3n8tombetdhsicokfinnotdoutlala.rlimestone withdasycladalgaetowardsthe
siliciclasticLlandeiloBekeFormation(Fig.2).Detaileddescription Unit4. Nodular algal limestone intercalating with siltstone about
ofthis section was provided by Keller(1956: 26), whorecognised 0.5-1.5 m thick, up to 22 mthickintotal, with brachiopodsofthe
threeunits (Fig. 3): (1)bedofintercalatingpolymictconglomerate Acculina-DulankarellaAssociation(Sample8231-40).
18 L.E.POPOV,L.R.M.COCKSANDI.F.NIKITIN
Anderkenyn-Akchoku Section (eastern side)
Tesikella
Association
PKAeaslrslaeosrcteirlloaapthiionna EA8cs1tse3onc4oigaltosisoan gBmiaovslatllruvosepcdosdasnd8134a MSoawbeerlblyaella
Association
8134b 8235U8u13n7 it 621
Unit55
\\/50m 55m
Unit2 ' Unit3 25m N
Kujandysai Section Parastrophina -KellerellaAssociation
2538
Tesikella
Association Mabella Sowerbyella
7611 Association 8219
Ectenoglossa
Association
Unit6
52 m
Unit 1
Unit2
Buldukbai-Akchoku Section
Acculina-Dulankarella
Association
Mabella-Sowerbyella 8231
.Association Units Mabella-SowerbyellaAssociation
Ectenoglossa 110
Association
120m
8227-80 36m ""* Unit4
\/"\/
8227-40 Unit3
8227-10 Unit2 I
Unit 1 Fault Unit6
20 40 60 80 100
--vr^jH Intercalating sandstone
DEVONIAN AnderkenFormation r-r-:-r-:-T:'-r and siltstone
Sandstone,
Conglomerate I I Siltstoneand mudstone cross-bedded
UPPERORDOVICIAN oa mLiicmreistticone, massive — -^ Sandstone,bedded.
DulankaraFormation pep|pe|| Limestone,algal, Sandstone
:g^$<a nodular
>*•*•* Conglomerate, pebbly,polymict Siltstone 252J Conglomerate, pebbly,
JoVoVoj polymict
Fig.5 SchematicstratigraphicsectionsoftheAnderkenFormationintheChu-IliRange,showingthepositionofsamplesanddistributionofbrachiopod
associations.
UPPERORDOVICIANBRACHIOPODSFROMKAZAKHSTAN
19
626 8223a,8223b A
843 100b 8221
Devonian
Fig.6 A,generalviewoftheAnderkenFormationattheAnderkenyn-Akchokusection,showinginformallithostratigraphicunitsdiscussedinthetextand
thepositionofbrachiopodlocalities.B,viewoflargecomplexcarbonatebuildupatAkchokuMountainintheupperpartoftheKujandysaisection.
PhotographsbyIgorNikitin.
Unit5. Massivemicriticlimestoneformingthecoreofthecarbon- unit contains numerous coalified plant remains ofAkdalaphyton
atemud-moundatthetopofthemountain,about30mthick. caradociconcentratedon severalbeddingsurfaces, brachiopodsof
The upper part of the Anderken Formation outcrops along the theSowerbyella-MabellaAssociation(Samples8229,8230)andthe
north-easternslopeofBuldukbai-AkchokuMountain. Itincludes: echinoderms Clivosocystissp.,DigitocrinuslevisandRistnacrinus
Unit6. Laminated,darkgreensiltstoneupto70mthickwithstorm bifidusStukalina.
bedsofcalcareoussandstonerichinbrachiopodcoquinasabout 10- Locality 5. Tesik River
15cmsthickandcrinoidcolumnals.Thetopisacharacteristicbedof
laminated brownish-violet siltstone about 0.5 m thick overlain by ThislocalityisonthesouthernsideoftheRiverTesikabout 1.5km
polymictconglomerate ofthe DulankaraFormation (Fig. 7B).The upstream of the bridge crossing the river on the highway from
20 L.E.POPOV,L.R.M.COCKSANDI.F.NIKITIN
Unit 5
8231-40
."••in
Fig.7 TheAnderkenFormationonthesouth-westernslopeofBuldukbai-AkchokuMountain.A,Units 1 to5,andSamplelocalities8227-80, 110and
8231-8240;B,Unit6andthecontactwiththeoverlyingDulankaraFormationandSamplelocalities8229and8230.PhotographsbyLarsHolmer.
Almaty to Balkhash (Fig. 1, locality 5). It is an isolated natural abundant Parastrophina-KellerellaAssociation (Sample 948).
exposure of about 20 m of pink to light red rocks of massive
micritic limestone forming the core of a mud-mound with lens- Locality 6. BurultasValley
like beds of biosparite at the base of the exposure. Most of the The BurultasValley (Fig. 1, locality 6) is about42-45 kmwestof
bioclasts are fragmented large cystoid columnals. It contains an Chiganak on the western Balkhash coast (northeastern part of
UPPERORDOVICIANBRACHIOPODSFROMKAZAKHSTAN 21
Quadrangle73°22'30"to73°30'E;45°to45°05'N).Asummaryof the River Karatal (Fig. 1, locality 7). Here it rests on the graded
the Ordovician geology and lithostratigraphy ofthis locality is in sandstonesand siltstonesoftheLlandeilotoLowerCaradoc upper
Nikitin et al. (1980, text-figs 18, 20). The Anderken Formation BaigaraFormation(Fig.2),orisincontactwith intrusives.About2
consists mainly ofsiliciclastic rocks with a thick unit ofpolymict km south-east of the Karatal river, south of Sorbulak spring, it
conglomeratesatthebaseandanumberofcarbonatemud-mounds comprises (1) polymict conglomerates more than 50 m thick, (2)
in the upper part (Fig. 3). The carbonate unit in the top of the medium- to fine-grained sandstones 169-170 m thick with
sequenceisabedofnodularalgallimestoneabout6-1 mthickwith Ectenoglossa sorbulakensis about 10-15 m above the base ofthe
numerous Girvanella sp., Cyclocrinites nikitini and Mastopora unit(Fig.3,Sample1024);and(3)intercalatingfine-grainedslightly
reticulata andbrachiopodsoftheAcculina—Dulankarella Associa- calcareous sandstones and siltstones about 60 m thick with the
tion (Locality 1041a ofNikitin = Sample 390/76 ofKovalevskii). TesikellaAssociationintheupper20moftheunit.Theupperpartof
which underlies a lens ofmassive, micritic limestone up to 20 m the section is an unfossiliferous unit ofintercalating fine-grained
thickwhichformingthemud-moundcore.Theunitthinsabout200 sandstones, lilac andredsiltstonesandmudstones several hundred
mwestwardfromLocality 1041a,whereitisrepresentedbybedded metres thick, which is overlain by the basal conglomerate of the
and nodular limestone with the brachiopods Pionodema opima, DulankaraFormation.
DulankarellalargaandMabellaconferta(Sample818).Theupper-
most 10 m of the underlying unit, of fine-grained sandstone Locality 8. Kotnak Mountains
intercalatingwith siltstone,contains adifferentbrachiopodassem-
blage with Tesikella necopina (Sample 818a), in association with oThfitsheiKnocotmnpalkeMtoeusnetcatiinosn,ofabtohuetA7ndkemrkSeWnoFforKmaartpikoundiusksWietlualt.eTdhweerset,
abundantcystoidcolumnals.
about1.5kmnorth-eastofthesaltmarsh(Figs 1,3,8),theformation
Locality 7. Sorbulak springon the east side ofthe consistsof: (1) siltstoneabout70mthickwith some stormbedsof
RiverKaratal calcareous sandstone about 10-20 cm thick with a coquina ofthe
bivalve Ctenodonta sp. (Samples 1017, 1019); (2) sandstone inter-
In the south Betpak-Dala Desert, about 20 km west of Baigara calating with siltstone in the upper part, total 40 m thick, with
Mountain,theAnderkenFormationiswellexposedonbothsidesof brachiopodsoftheTesikellaAssociationinthelower10moftheunit
QUATERNARY
Saltmarsh
DEVONIAN
ES
ORDOVICIAN
Anderken Formation
Conglomerate
Sandstone
vv^j Sandstoneand
t>;ri£3 siltstone
Sandstonewithcoquina
*':X storm beds
2 km
i i_
Fig.8 GeologicalmapshowingthedistributionoftheAnderkenFormationandthepositionoffossillocalitiesintheareaabout7kmsouth-westof
Karpkudukwell,KotnakMountains.
22 L.E.POPOV,L.R.M.COCKSANDI.F.NIKITIN
Table 1 CompositionofEctenoglossaAssociationfromtheAnderkenFormationshowingnumberofcompleteshells,ventralanddorsalvalves
respectively.
Samplenumber 7612 8130a 8130- 8223-1 8227-10 8227^10 8227-80 F-1024
Numberofspecimens 27 1 2 6 4 3 12
Ectenoglossasorbulakensis 24:3:2 0:1:0 0:2:0 0:1: 6:0:0 0:3:4 0:3:3 0:8:12
(Sample 1018a)belowabedofskeletalcalcareoussandstoneabout eigenvectors corresponding to three maximum directions ofvaria-
5mthickwithanallochthonousbrachiopodfaunawithamixtureof tion(F1-F3)areillustratedontwotwo-dimensionaldiagrams(Fig.
taxaofthe TesikellaandMabella-SowerbyellaAssociations(Sam- 9).TheDiversityIndexiscalculatedasthenumberofspeciesminus
ple 1018); (3)intercalatingbedsofsandstoneandpebblypolymict 1 divided by the natural logarithm of the number of brachiopod
conglomerateabout80-90mthick;and(4)siltstonewithafewbeds individualsinthe sample (fordetails seeWilliamsetal. 1981).The
of fine-grained sandstone, total 130 m thick and overlain analysis of taxonomic composition and relative abundance of
unconformablybyDevonianconglomerate. brachiopod taxa from numerous localities and samples in the
AnderkenFormationallowsrecognitionofsixbrachiopodassocia-
tions characterisedbelow. They are interpreted within the Benthic
FAUNALASSOCIATIONS Assemblage(BA)schemeofBoucot(1975).
1. TheEctenoglossaAssociation.Thisisamonospecificlingulide
TheAnderkenFormationisatransgressivesequencefromnearshore association of BA-1 with Ectenoglossa sorbulakensis in the
to outershelfdeposits with predominantly siliciclastic deposition. Anderkenyn-Akchoku, Kujandysai and Buldukbai-Akchoku sec-
The lower part of the formation, below the main horizon with tions,theeastsideoftheKopalysaiRiverandonthesouthernsideof
carbonate build-ups in theAnderkenyn-Akchoku, Kujandysai, theKaratalRiversouthofSorbulakspring(Table 1).Theassemblage
Buldukbai-Akchoku and Burultas sections, was formed in tide- shows patchy distribution in lithologies of coarse- to medium-
dominated environments of mostly tidal flat deposits with grainedsandswithsubhorizontalandcross-beddedstratification.In
characteristicsetsofpebblyconglomerates,cross-beddedandlami- mostofthelocalitiesshellsaredisarticulatedonthebeddingsurfaces
natedsands,coquinastormbedsandtracesoftidalcurrents.Carbonate andonlyinSample7612doconjoinedvalvespredominate(89%of
build-ups in the upper part of the formation preserve numerous individuals). A cluster of six articulated shells preserved in life
tracesofphotosyntheticactivityandcontainadiversefloraofgreen positioninclinedfrom62°-80°tothebeddingsurfacewasrecovered
andredalgae(Nikitinetal. 1974);suggestingformationinshallow from Sample 8227-40 in the Buldukbai-Akchoku section, which
depthswithintheeuphoticzone.Theoutershelfdepositsarerecorded confirmstheinfaunalmodeoflifeofthislingulide.Thegastropods
onlyinthesouth-easternChu-Ili Rangeandconsistofsiltandmud Lophospira sp. and Latitenia kasachstanica Vostokova and the
containinggraptolites.Thebenthicfaunaisdominatedbytrilobites bivalved molluscs Endomionia fecinda, Ctenodonta sp. and
butincludesoneoftheearliestrecordsoftheFoliomenabrachiopod Cyrtodontalsubcentralis(Khalfin 1958), which arewidespreadin
fauna.Apollonov (1975)hasdescribedthe trilobiteassociationsof similar lithologies and form coquina storm beds, do not co-occur
themiddleandlateOrdovicianoftheChu-IliPlate. togetherwiththelingulides;forexample,inSample8130abedding
A matrix based on the distribution of about 1800 brachiopod surface with Ectenoglossa sorbulakensis and a storm bed with
specimens from 33 samples within the Anderken Formation was molluscsandthetrilobiteEokosovopeltisromanovskyiareseparated
subjected to Principal Component Analysis (Etter 1999). Plots of byan interval onlyabout2.5 mthick. ItislikelythatEctenoglossa
Table2 CompositionofTesikellaAssociationfromtheAnderkenFormationshowingnumberofcompleteshells,ventralanddorsalvalvesrespectively.
Samplenumbers 127 818a F-1018a 7611 8128 F-1018 F-1024b 8127-2b 8138
Numberofspecimens 18 22 32 7 18 172 20 2
Diversityindex 0.33 0.65 0.58 0.51 1.38 3.11 2.16
Trematissp. 0:0:1
Tesikellanecopina 3:14:12 0:13:12 0:16:7 1:5:5 0:4:2 1:4:3 0:2:2 0:1:0 0:2:0
Longvillialanx 0:4:5 2:7:3
Glyptomenaonerosa 0:1:5
Christianiaegregia 0:7:18 0:2:7
Limbimurinasp. 0:1:1
Isophragmaimperator 1:36:34
Acculinakulanketpesica 0:0:1 0:1:2
Mabellaconferta 1:0:0 0:1:2
Shlyginiafragilis 0:6:4
Anaptambonitesorientalis 1:4:3
Sowerbyellarukavishnikovae 0:10:11 0:8:17 0:9:10
Bicuspinarukavishnikovae 3:1:9
Plectorthisbundtasica 0:0:1 1:6:7
Dolerorthisexpressa 1:12:9
Phragmorthisconciliata 0:4:4 0:1:0
Eodalmanellaextera 4:4:0 0:0:1 1:28:22
Pionodemaopima 2:8:5
Rhynchotremasp.nov. 1:0:0
Didxmelasmacf.transversa 0:0:1