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NEW DATA ON THE LATE ORDOVICIAN TRILOBITE FAUNAS OF KAZAKHSTAN: IMPLICATIONS FOR BIOGEOGRAPHY OF TROPICAL PERI-GONDWANA

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Selected Ordovician trilobites from Kazakhstan. Specimens deposited in the National Museum of Wales Cardiff (NMW), and F.N. Chernyshev Central Geological Scientific Research and Exploration Museum (CNIGR), St Petersburg. 1, 6, 7, Alperillaenus intermedius Ghobadi Pour and Popov, 2009; Darriwilian, Kypchak Limestone, northern Betpak-Dala; 1, NMW 2008.34G.3, cranidium, x2; 6, NMW 2008.34G.11, hypostome, x5.5; 7, NMW 2008.34G.9, pygidium, x5.5. 2, 3, Ampyxinella balashovae Koroleva, 1965; Sandbian, Sarytuma, West Balkhash Region; 2, NMW2008.34G.150, internal mould of cranidium, x3; 3, NMW2008.34G.151, internal mould of pygidium, x3. 4, Agerina acutilimbata Ghobadi Pour et al., 2011, Katian, Karagach Formation, east side of the Ayaguz River, about 7 km north of Akchii village, Trabagatai Range; NMW 2005.32G.135, holotype, articulated exoskeleton, latex cast, x5. 5, 10, Acrolichas clarus Koroleva, 1959, Sandbian, Myatas Formation, northern coast of Atansor Lake; 5, NMW2008.34G.155, cranidium, x4; 10, NMW2008.34G.156, incomplete pygidium, x4. 8, 9, Sphaerexochus conusoides Koroleva, 1959; age and locality as Fig. 2.5; 8, NMW2008.34G.157, cranidium, x2.5, 9, NMW2008.34G.158, pygidium, x2.2. 11-13, Damiraspis margiana Ghobadi Pour and Popov, 2009, age and locality as Fig. 2.1; 11, NMW 2008.34G.46, cranidium, x4. 12, NMW 2008.34G.42, holotype, hypostome, x1.1; 13, NMW 2008.34G.48, partly exfoliated pygidium, x2.5. 14, Caganaspis unica Kolobova, 1985, area about 7 km south-west of Alakul Lake, West Balkhash Region, NMW2008.34G.149, articulated exoskeleton, latex cast, x4.5. 15, Telephina omega Koroleva, 1982, age and locality the same as Fig. 2.2; NMW2008.34G.152, internal mould of cranidium, x 3.5. 16, Robergia? sp., age and locality the same as Fig. 2.14; NMW2008.34G.153, cranidium, latex cast, x5. 17, Nileus sp., age and locality the same as Fig. 2.4;
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Content may be subject to copyright.
J.C. Gutiérrez-Marco, I. Rábano and D. García-Bellido (eds.),
Ordovician of the World.
Cuadernos del Museo Geominero, 14. Instituto Geológico y Minero de España, Madrid. ISBN 978-84-7840-857-3
© Instituto Geológico y Minero de España 2011
171
NEW DATA ON THE LATE ORDOVICIAN TRILOBITE FAUNAS OF KAZAKHSTAN:
IMPLICATIONS FOR BIOGEOGRAPHY OF TROPICAL PERI-GONDWANA
M. Ghobadi Pour
1
, L.E. Popov
2
, L. McCobb
2
and I.G. Percival
3
1
Department of Geology, Faculty of Sciences, Golestan University, Gorgan, Iran.
mghobadipour@yahoo.co.uk. m.ghobadipour@gu.ac.ir
2
Department of Geology, National Museum of Wales, Cardiff CF10 3NP, Wales, United Kingdom.
leonid.popov@museumwales.ac.uk, lucy.mccobb@museumwales.ac.uk
3
Geological Survey of NSW, 947-953 Londonderry Road, Londonderry 2753, New South Wales, Australia.
ian.percival@industry.nsw.gov.au
Keywords: Late Ordovician, Gondwana, Kazakhstan, trilobites, biogeography.
INTRODUCTION
During the Late Ordovician, microplates and volcanic arc systems presently incorporated into the
Kazakhstanian orogen converged to form a huge archipelago, which extended far into the ocean along
subequatorial latitudes west of the tropical Australasian sector of Gondwana (Popov et al., 2009). The
shelves of volcanic islands and microcontinents within this archipelago supported diverse benthic faunas,
with trilobites as one of the most important components. Kazakhstanian Late Ordovician trilobite faunas
have been documented in a number of publications (Ghobadi Pour et al., 2011; Koroleva, 1982 and
references therein). Koroleva (1982) gave up to date summaries with outlines of taxonomic diversity and
geographical distributions of trilobite taxa throughout Kazakhstan. A total of about 110 genera and more
than 200 species were counted, but their generic affiliation often requires revision. Apollonov (1975)
published a brief review of the Kazakhstanian trilobite biofacies, whereas Fortey and Cocks (2003) gave a
brief outline of biogeographic affinities of Kazakhstanian faunas throughout the Ordovician, mainly based
on personal assessment of unpublished collections by Richard Fortey. Nevertheless, existing data on
characters of trilobite faunas from individual terranes are still incomplete and there was little progress in
their study during the last 25 years.
In spite of significant losses of collections and geological information after the collapse of the Soviet
Union, there is a substantial amount of unpublished data which has been preserved and is available for
study. It includes an enormous trilobite collection assembled by the late Michael K. Apollonov, which covers
almost all areas in Kazakhstan where Ordovician deposits are present. In addition to published
information, new data are presented in this paper, mainly based on a preliminary assessment of the
samples available from Apollonov’s collections, which are currently under study.
ORDOVICIAN PALAEOGEOGRAPHY OF KAZAKHSTANIAN TERRANES
Three major clusters of early Palaeozoic terranes can be recognised in the Kazakhstanian orogen. The
southern cluster includes three major crustal terranes (i.e. Chu-Ili, North Tien Shan and Karatau-Naryn),
which were amalgamated together by the Late Silurian (Popov et al., 2009) (Fig. 1). The published record
of Mid to Late Ordovician trilobite faunas of Chu-Ili is the most complete in comparison with other regions
of Kazakhstan, whereas it is virtually nonexistent for North Tien Shan (Ghobadi Pour et al., 2009; Koroleva,
1982 and references here).
172
M. Ghobadi Pour, L.E. Popov, L. McCobb and I.G. Percival
Figure 1. Palaeogeographical reconstruction for the Upper Ordovician (Katian) showing geographical distribution of selected
biogeographically informative trilobite genera. Position of the major early Palaeozoic continents mainly after Fortey and Cocks
(2003) with emendations after Popov et al. (2009). Surface water circulation for a Northern Hemisphere summer is mainly after
Wilde (1991). Abbreviations for Kazakhstanian island arcs and microplates are as follows: A-Zh – Atasu-Zhamshi, Ak – Akbastau,
Ch-T – Chingiz-Tarbagatai, K-N – Karatau-Naryn, NTS – North Tien Shan.
The southern cluster of Kazakhstanian terranes is separated by an oceanic suture from the Atasu-
Zhamshi microplate (Apollonov, 2000; Popov et al., 2009) (Fig. 1). The area north-east of Atasu-Zhamshi
represents a complicated mosaic of island arc and continental fragments, separated by ophiolitic belts
associated with sutures and often strongly reworked since the Early Palaeozoic (for summary, see Popov et
al., 2009; Windley et al., 2007). At least three major island arc systems can be recognised, including
Akbastau, Chingiz-Tarbagatai and Boshchekul. Published information on the Late Ordovician trilobite
faunas of the Chingiz-Tarbagatai and Boshchekul regions was reviewed by Koroleva (1982 and references
here) and recently by Ghobadi Pour et al. (2011).
Another group of early Palaeozoic terranes are those of north-central Kazakhstan, i.e. the Kalmyk Kol-
Kokchetav unit of S
,
engör & Natal’in (1996) or Shatsk and Kokchetav microplates of Dobretsov et al. (2006)
and adjacent island arcs. Data on the Neoproterozoic to Early Palaeozoic geological history of this north-
central sector of the Kazakhstanian orogen, provided by Dobretsov et al. (2006), substantiates the idea
that these units did not interact with the south Kazakhstanian cluster of terranes throughout the
Cambrian-Ordovician. Koroleva (1982) published a detailed outline of Late Ordovician trilobite
distributions in the Selety, Ishim and Stepnyak regions, based in a significant part on her earlier
publications.
TRILOBITE BIOFACIES
In the late Darriwilian – Sandbian, asaphid-illaenid biofacies were characteristic for inshore
environments in almost all Kazakhstanian terranes, but they are well documented only for Chu-Ili. A good
example is the monotaxic
Isotelus’ romanovskyi
Association of Apollonov (1975), which spread widely on
a shallow clastic shelf across Chu-Ili. It replaced the lingulid
Ectinoglossa
Association seaward and was
confined to a sandy bottom, nearshore setting, inhabited mainly by gastropods and bivalved molluscs.
Isotelus’ romanovskyi
Weber, 1948 is probably assignable to
Damiraspis
(Fig. 2.11-13), but hypostome
morphology in this species is as yet unknown. On the shallow carbonate shelf of Chu-Ili, the asaphids
Damiraspis
and
Farasaphus
formed oligotaxic communities, usually in association with the endemic illaenid
Alperillaenus
(Fig. 2.1, 6-7) as a second major component. Other minor components comprised
Ceraurinella
?,
Eorobergia
,
Pliomerina
(Fig. 2.21) and
Sphaerexochus
(Ghobadi Pour et al., 2009).
The pliomerid-styginid biofacies first emerged during the Sandbian. At that time, it was most
characteristic for silty bottom, nearshore settings and probably occupied a quiet environment, affected
occasionally by seasonal storms. During the Sandbian, these biofacies were dominated by styginids, namely
Dulanaspis
,
Styginella
and
Bronteopsis
. Other common taxa are
Lonchodomas
,
Pliomerina
,
Remopleurides
and
Sinocybele
(Fig. 2.22), whereas asaphids are rare to almost absent. During the Katian, these
associations gradually replaced asaphid-dominated associations nearshore, and there were changes in the
taxonomic composition of the assemblages.
Pliomerina
and
Remopleurides
proliferated and became
dominant by the mid-Katian, whereas the proportion of styginids gradually declined.
The illaenid-cheirurid biofacies was confined to the carbonate build-ups, which became widespread
throughout Kazakhstanian island arcs and microcontinents in the Sandbian–Katian. This biofacies was
characterised by rich generic diversity, but remains very poorly known. In addition to the nominative
families, asaphids, lichids, pliomerids, remopleuridids, raphiophorids and styginids usually occur. Such
genera as
Acrolichas
(Fig. 2.5, 10),
Eokosovopeltis
,
Glaphurina
,
Holotrachellus
,
Metopolichas
and
Sphaerexochus
(Fig. 2.8-9) are the most characteristic. The nileid biofacies is known from the offshore
173
NEW DATA ON THE LATE ORDOVICIAN TRILOBITE FAUNAS OF KAZAKHSTAN: IMPLICATIONS FOR BIOGEOGRAPHY OF TROPICAL PERI-GONDWANA
environment of almost all major Kazakhstanian terranes. Faunas characteristic of this biofacies usually lack
distinct dominant taxa and may be rather diverse. For example, a nileid association recently described from
the lower Katian Karagach Formation of the Tarbagatai Range (Ghobadi Pour et al., 2011) contains 15
different trilobite genera, including leiostegiids (
Aegirina
), asaphids (
Birmanites
), encrinurids
(
Encrinuroides
,
Sinocybele
), remopleuridids, raphiophorids and shumardiids (Fig. 2.4, 17-19).
The raphiophorid biofacies probably occupied the disphotic zone in deeper water offshore. Trilobite
taxa characteristic of this biofacies are often blind (many raphiophorid genera), or possess hypertrophic
eyes (e.g.
Arator
and
Telephina
). Trilobite associations of this biofacies may be oligotaxic (e.g.
Bulbaspis
Association from the Dulankara Formation of Chu-Ili terrane), or display remarkable taxonomic diversity
with more than 25 genera (
Caganaspis
Association from the Bestamak Formation of the Chingiz Range).
The list of characteristic genera includes the three-segmented raphiophorid
Caganaspis
(Fig. 2.14) and
remopleuridids (e.g.
Arator
,
Eorobergia
,
Robergia
?) (Fig. 2.16) that are widespread in the Chu-Ili,
Boshchekul and Chingiz-Tarbagatai terranes, but are as yet unknown outside Kazakhstan. There are also
more widespread taxa, e. g.
Ampyxinella
,
Bulbaspis
,
Endymionia
,
Birmanites
,
Dionide
and
Telephina
(Fig.
2.2, 3, 15), which are also documented from the Australasian sector of Gondwana. A significant proportion
of Kazakhstanian faunas characteristic of the raphiophorid biofacies remain formally undescribed.
The deepest water olenid biofacies was not previously documented from Kazakhstan. In Atasu-
Zhamshi, the olenid
Porterfieldia
occurs in association with
Endymionia
in black limestones of the Shundy
Formation (Sandbian). The only other fossils to occur at that locality are radiolarians. In Chu-Ili, olenid
trilobites occur in black graptolitic shales of Katian age, exposed on the Akkerme Peninsula on the western
coast of Balkhash Lake. In this locality, the olenid
Triarthrus
(Fig. 2.20) occurs in association with
Dionide
,
Caganaspis
and a new, as yet undescribed, harpetid genus.
IMPLICATIONS FOR BIOGEOGRAPHY
In spite of incomplete knowledge of Kazakhstanian trilobite faunas, there is good evidence that during
the Late Ordovician they exhibited similar biogeographical signatures, suggesting affinity to the
Eokosovopeltis-Pliomerina
Province of Webby et al. (2000). Indeed,
Eokosovopeltis
and
Pliomerina
proliferated on the shallow shelves of all major Kazakhstanian terranes. However, significant work is still
needed to establish the faunal signatures of individual Kazakhstanian island arcs and microplates.
174
M. Ghobadi Pour, L.E. Popov, L. McCobb and I.G. Percival
Figure 2. Selected Ordovician trilobites from Kazakhstan. Specimens deposited in the National Museum of Wales Cardiff (NMW), and
F.N. Chernyshev Central Geological Scientific Research and Exploration Museum (CNIGR), St Petersburg. 1, 6, 7,
Alperillaenus
intermedius
Ghobadi Pour and Popov, 2009; Darriwilian, Kypchak Limestone, northern Betpak-Dala; 1, NMW 2008.34G.3, cranidium,
x2; 6, NMW 2008.34G.11, hypostome, x5.5; 7, NMW 2008.34G.9, pygidium, x5.5. 2, 3,
Ampyxinella balashovae
Koroleva, 1965;
Sandbian, Sarytuma, West Balkhash Region; 2, NMW2008.34G.150, internal mould of cranidium, x3; 3, NMW2008.34G.151, internal
mould of pygidium, x3. 4,
Agerina acutilimbata
Ghobadi Pour et al., 2011, Katian, Karagach Formation, east side of the Ayaguz River,
about 7 km north of Akchii village, Trabagatai Range; NMW 2005.32G.135, holotype, articulated exoskeleton, latex cast, x5. 5, 10,
Acrolichas clarus
Koroleva, 1959, Sandbian, Myatas Formation, northern coast of Atansor Lake; 5, NMW2008.34G.155, cranidium,
x4; 10, NMW2008.34G.156, incomplete pygidium, x4. 8, 9,
Sphaerexochus conusoides
Koroleva, 1959; age and locality as Fig. 2.5;
8, NMW2008.34G.157, cranidium, x2.5, 9, NMW2008.34G.158, pygidium, x2.2. 11-13,
Damiraspis margiana
Ghobadi Pour and
Popov, 2009, age and locality as Fig. 2.1; 11, NMW 2008.34G.46, cranidium, x4. 12, NMW 2008.34G.42, holotype, hypostome, x1.1;
13, NMW 2008.34G.48, partly exfoliated pygidium, x2.5. 14,
Caganaspis unica
Kolobova, 1985, area about 7 km south-west of
Alakul Lake, West Balkhash Region, NMW2008.34G.149, articulated exoskeleton, latex cast, x4.5. 15,
Telephina omega
Koroleva,
1982, age and locality the same as Fig. 2.2; NMW2008.34G.152, internal mould of cranidium, x 3.5. 16,
Robergia
? sp., age and
locality the same as Fig. 2.14; NMW2008.34G.153, cranidium, latex cast, x5. 17,
Nileus
sp., age and locality the same as Fig. 2.4;
175
NEW DATA ON THE LATE ORDOVICIAN TRILOBITE FAUNAS OF KAZAKHSTAN: IMPLICATIONS FOR BIOGEOGRAPHY OF TROPICAL PERI-GONDWANA
NMW 2005.32G.193, cephalon with attached thoracic segments, latex cast, x6. 18,
Aethedionide
sp., Sandbian, Karagach Formation,
locality as Fig. 2.4; NMW 2005.32G.191, pygidium, internal mould, x4. 19,
Birmanites akchiensis
Ghobadi Pour et al., 2011, age and
locality the same as Fig. 2.4; NMW 2005.32G.181, holotype, cranidium, latex cast of external mould, x1.5. 20,
Triarthrus
sp., Katian,
Ak-Kerme Peninsula, west coast of Balkhash Lake, NMW2008.34G.154, cranidium, x9. 21,
Pliomerina
aff.
sulcifrons
(Weber, 1948),
age and locality as Fig. 2.1; NMW 2008.34G.25, cranidium, x5. 22
, Sinocybele weberi
(Kolova, 1936), Katian, Besharyk Formation,
Dzhebagly Mountains; CNIGR 60/4263, lectotype, incomplete dorsal exoskeleton, latex cast, x1.8.
Recent studies also demonstrate that the asaphid trilobites
Basilicus
and
Basiliella
were probably
confined to peri-Iapetus settings, while the Kazakhstanian and Australasian species traditionally assigned
to these genera in fact belong to separate asaphid lineages (Ghobadi Pour et al., 2009), which evolved
independently in tropical peri-Gondwana and should be assigned to different genera (i.e.
Damiraspis
and
Farasaphus
). Remarkably, although these asaphids commonly occur in the Australian sector of Gondwana,
they are absent from the Darriwilian–Katian rocks of South China, where they are replaced by genera of
the Subfamily Nobiliasaphinae (e.g.
Liomegalaspides
). A similar pattern was observed for
Eokosovopeltis
,
which is absent from the Sandbian to early Katian of South China (Zhou and Zhen, 2009). Zhou and Zhen
(2009) recently suggested that Australian trilobite faunas had closest affinities with those of North China
during the Arenig-Caradoc interval (=Sandbian–early Katian). It is likely that there was a continuous belt
of tropical peri-Gondwanan, shallow water faunas during the Sandbian-early Katian, which included
Kazakhstanian terranes, North China and the Australian sector of Gondwana.
The most likely explanation can be found in features of oceanic surface circulation along the western
coast of Gondwana (Fig. 1). It is well established that the Australian sector of Gondwana, North China and
Kazakhstanian microplates and island arcs occupied a subequatorial position in the Ordovician, whereas
a more temperate latitude is evident for South China during the Early to Mid Ordovician, based on
palaeomagnetic data, characteristics of shallow marine benthic communities and sedimentation (Fortey
and Cocks, 2003). In particular, the occurrence in South China of trilobites from the Family
Reedocalymeninae and
Taihungshania
represents a distinct link with temperate to high latitude
Gondwanan faunas (e.g. Armorica, Turkish Taurids, Iran), whereas they are virtually absent from
Kazakhstanian terranes and the Australian sector of Gondwana. It is probable that a cool water, South
Subpolar Current, running along the western Gondwanan coast (Wilde, 1991), might have an effect on
climate comparable to the present-day Humboldt Current. As a result, average annual temperatures of
surface waters along the coasts of the South China continent during the Early to Mid Ordovician were
considerably lower than in subequatorial peri-Gondwana, which prevented the immigration of some warm
water taxa. Only in the Katian, when South China entered low latitudes, did affinity with the shallow shelf
faunas of the Kazakhstanian terranes become firmly established.
Acknowledgements
The research of Mansoureh Ghobadi Pour was supported by the Golestan University, Gorgan. Leonid
Popov and Lucy McCobb acknowledge support from the National Museum of Wales. Ian Percival publishes
with permission of the Director, Geological Survey of New South Wales.
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NEW DATA ON THE LATE ORDOVICIAN TRILOBITE FAUNAS OF KAZAKHSTAN: IMPLICATIONS FOR BIOGEOGRAPHY OF TROPICAL PERI-GONDWANA
... FOSSILS AND STRATA 47 (2021) Ordovician brachiopods from Kazakhstan 5 documented by and . The complex geology of the area was discussed by Keller & Lisogor (1954), Nikitin (1972), Nikitin et al. (1980), Nikitina et al. (2006), andGhobadi Pour et al. (2009), but is still not yet fully understood. The area was initially surveyed by L. E. Popov in 1973Popov in and 1974Popov in and again between 1986Popov in and 2004 with the late E. V. Alperovich and E. A. Vinogradova. ...
... The lithostratigraphy (Kushaky, Savid, Algabas, and Kuyandy formations) previously applied to the Ordovician in the region was imported from the distant Sarysu-Teniz Region by Nikitin et al. (1980), Nikitin (1991), and Nikitina et al. (2008), but that region is within the North Tien Shan Microcontinent on the opposite side of a Silurian suture Popov & Cocks 2017) and thus its terminology cannot sensibly be used in the Chu-Ili Terrane. Vinogradova (in Ghobadi Pour et al. 2009) found that andesite-basalt volcanic rocks assigned to the Savid Formation in the Golubaya Gryada area (Locality 6 on Fig. 1) represent a chain of exhumed intrusive subvolcanic bodies of younger Palaeozoic age which have no relation to the exposed Upper Ordovician stratigraphical succession as was suggested in some previous publications. ...
... Limestones of Unit 2 contain a trilobite assemblage (including Alperillaenus intermedius, Damiraspis margiana, Eorobergia sp., Farasaphus singularis, and Pliomerina aff. P. sulcifrons) together characteristic of the asaphid biofacies conned to inshore environments (Ghobadi Pour et al. 2009;. Pebbles from the conglomerate beds include black cherts, quartz, ne siliciclastic, and volcanic rocks, suggesting a growing accretionary wedge as a possible source. ...
Chapter
Chu‐Ili, now in Kazakhstan, was a substantial independent equatorial microcontinental terrane in Ordovician times, with a small Precambrian core fringed by several island arcs. Its mid‐Ordovician (late Darriwilian to early Katian) faunas were a major evolutionary hotspot within an equatorial archipelago at a period when Palaeozoic sea levels and temperatures were at their highest. As well as reviewing the previously described brachiopods from elsewhere in Chu‐Ili, the mid‐Ordovician brachiopods of the West Balkhash Region, which outcrops west of Lake Balkhash within Chu‐Ili, are newly described here, mainly from the Berkutsyur and Baigara formations. Many represent the earliest occurrence of their lineages, notably the oldest member of the Order Atrypida. More than twelve brachiopod associations are defined, many for the first time and together hosting 73 genera and over 91 species. The new family Kellerellidae is erected within the superfamily Lissatrypoidea. New genera are Aploobolus (Obolidae), Doughlatomena (Rafinesquinidae), and Altynorthis , Lictorthis , and Baitalorthis (all Plectorthidae), Baitalorhynchus (Sphenotretidae), Lydirhyncha (Ancistrorhynchidae) and Costistriispira (Kellerellidae). Eleven new species, including Aploobolus ? tenuis , Doughlatomena splendens , Bimuria karatalensis , Apatomorpha akbakaiensis , Lepidomena betpakdalenis , Sonculina baigarensis , Altynorthis betpakdalensis , Altynorthis vinogradovae , Phaceloorthis ? corrugata , Batailorhyncha rectimarginata and Costistriispira proavia , and one new subspecies Sowerbyella ( Sowerbyella ) verecunda baigarensis are also erected. The global palaeogeographical affinities of all the Chu‐Ili brachiopod faunas are discussed, as well as Chu‐Ili's place within the peri‐Gondwanan archipelago. Newly named stratigraphical units are the Berkutsyur (Darriwilian to early Sandbian) and overlying Kopkurgan (Sandbian to Katian) formations within West Balkhash, and the Tastau (Darriwilian) and Takyrsu (Darriwilian to early Sandbian) formations within the northern Betpak‐Dala desert.
... The complex geology of the area was discussed by Keller & Lisogor (1954), Nikitin (1972), Nikitin et al. (1980), Nikitina et al. (2006), andGhobadi Pour et al. (2009), but is still not yet fully understood. The area was initially surveyed by L. E. Popov in 1973Popov in and 1974Popov in and again between 1986Popov in and 2004 with the late E. V. Alperovich and E. A. Vinogradova. ...
... The lithostratigraphy (Kushaky, Savid, Algabas, and Kuyandy formations) previously applied to the Ordovician in the region was imported from the distant Sarysu-Teniz Region by Nikitin et al. (1980), Nikitin (1991), and Nikitina et al. (2008), but that region is within the North Tien Shan Microcontinent on the opposite side of a Silurian suture Popov & Cocks 2017) and thus its terminology cannot sensibly be used in the Chu-Ili Terrane. Vinogradova (in Ghobadi Pour et al. 2009) found that andesite-basalt volcanic rocks assigned to the Savid Formation in the Golubaya Gryada area (Locality 6 on Fig. 1) represent a chain of exhumed intrusive subvolcanic bodies of younger Palaeozoic age which have no relation to the exposed Upper Ordovician stratigraphical succession as was suggested in some previous publications. ...
... Limestones of Unit 2 contain a trilobite assemblage (including Alperillaenus intermedius, Damiraspis margiana, Eorobergia sp., Farasaphus singularis, and Pliomerina aff. P. sulcifrons) together characteristic of the asaphid biofacies confined to inshore environments (Ghobadi Pour et al. 2009;. Pebbles from the conglomerate beds include black cherts, quartz, fine siliciclastic, and volcanic rocks, suggesting a growing accretionary wedge as a possible source. ...
... The Late Ordovician (Sandbian to Hirnantian) rhynchonelliform brachiopods of the Chingiz Range are well documented (Nikitin and Popov 1984;Popov and Cocks 2014), but trilobite data came mostly from the Upper Ordovician of the Tarbagatai Range (Kolobova, 1972;Ghobadi Pour et al. 2011a, 2011c. The occurrence of Dulanaspis, Pliomerina, and Sinocybele in the latter assemblages is a clear signature of the Late Ordovician east Peri-Gondwana Eokosovopeltis-Pliomerina Fauna (Edgecombe and Webby 2006;Zhou and Zhou 2006). ...
... That is supported by the occurrence of the Early Ordovician (Floian) trilobite Tanhungshania in Karatau-Naryn, which is otherwise known from South China and temperate latitude peri-Gondwana (Alborz, Turkish Taurides, and Armorica), but is unknown elsewhere in Kazakhstan, or in the Australasian sector of Gondwana ). In contrast, reedocalymenine trilobites and the Saucrorthis Brachiopod Association, common in South China, are unknown from the Kazakh terranes (Turvey 2005b;Ghobadi Pour et al. 2011c;Percival et al. 2011). ...
... A similar pattern is seen in the Darriwilian trilobites and in South China the shallow shelf asaphid biofacies were dominated by genera of the Subfamily Nobiliasaphinae, especially Liomegalaspides (Turvey 2005a). Study of asaphids from the Chu-Ili Terrane reveals two distinct genera Damiraspis and Farasaphus which occur in the Australasian sector of Gondwana (Thailand and New South Wales) as well as Argentina (Ghobadi Pour 2009;Ghobadi Pour et al. 2011c). Zhou and Zhen (2009) noted that Eokosovopeltis, one of the index taxa for the Eokosovopeltis-Pliomerina Province of Webby et al. (2000), was already present in the Sandbian of North China, the Australasian sector of Gondwana, and the Kazakh terranes, but did not appear in South China until the Katian. ...
Article
Popov, L.E. and Cocks, L.R.M. 2017. Late Ordovician palaeogeography and the positions of the Kazakh ter-ranes through analysis of their brachiopod faunas. Acta Geologica Polonica, 67 (3), 323–380. Warszawa. Detailed biogeographical and biofacies analyses of the Late Ordovician brachiopod faunas with 160 genera, grouped into 94 faunas from individual lithotectonic units within the Kazakh Orogen strongly support an archipelago model for that time in that area. The Kazakh island arcs and microcontinents within several separate clusters were located in the tropics on both sides of the Equator. Key units, from which the Late Ordovician faunas are now well known, include the Boshchekul, Chingiz-Tarbagatai, and Chu-Ili terranes. The development of brachiopod biogeography within the nearly ten million year time span of the Late Ordovician from about 458 to 443 Ma (Sandbian, Katian, and Hirnantian), is supported by much new data, including our revised identifications from the Kazakh Orogen and elsewhere. The Kazakh archipelago was west of the Australasian segment of the Gondwana Supercontinent, and relatively near the Tarim, South China and North China continents, apart from the Atashu-Zhamshi Microcontinent, which probably occupied a relatively isolated position on the southwestern margin of the archipelago. Distinct faunal signatures indicate that the Kazakh terranes were far away from Baltica and Siberia throughout the Ordovician. Although some earlier terranes had joined each other before the Middle Ordovician, the amalgamation of Kazakh terranes into the single continent of Kazakhstania by the end of the Ordovician is very unlikely. The Late Ordovician brachiopods from the other continents are also compared with the Kazakh faunas and global provincialisation statistically determined.
... Since Kobayashi (1940Kobayashi ( , 1951, numerous authors agree on the palaeobiogeographic value of Taihungshania (Zhou and Dean, 1989;Fortey and Cocks, 2003;Ghobadi Pour et al., 2009, 2011Gutiérrez-Marco et al., 2017) as a proxy for discussing the faunal affinities and relative arrangement of some terranes on the south of the Rheic ocean during the Ordovician. Faunal links are numerous and well documented between the south Rheic margin and the south China during the Middle and particularly the Upper Ordovician (Fortey and Cocks, 2003;Ghobadi Pour et al., 2011Fortey et al., 2022), including Sardinia Leone, 1997, 2007). In marked contrast, during the Lower Ordovician the trilobite fauna is significantly less diversified with widespread and therefore less relevant taxa. ...
... There are rather extensive published accounts of brachiopods (Borissiak 1955;Nikitin 1974;Popov 1975;Nazarov andPopov 1976, 1980;Klenina 1984;Nikitin and Popov 1984;Popov and Cocks 2014), conodonts (Zhylkaidarov 1998;, Katian rugose corals (Litvinovich et al. 1963;Sultanbekova 1986) and Late Ordovician echinoderm ossicles (Stukalina 1988(Stukalina , 2000. Sandbian trilobites are known from publications of Kolobova (1983) andGhobadi Pour et al. (2011b), while late Katian species of Ampyxinella, Dulanaspis, Menoparia, Nankinolithus [=Tretaspis], Pliomerina and Remopleurides were described by Kolobova (1972) and Apollonov (1974). The Late Ordovician (Katian) tabulate corals are documented by Bondarenko (in Litvinovich et al. 1963) and Kovalevskii (1964aKovalevskii ( , b, 1972Kovalevskii ( , 1980. ...
Article
A comprehensive review of the current state of research on Kazakh Ordovician litho-, bio- and chronostratigraphy is presented. An Ordovician lithostratigraphic framework applied to eight Kazakh first-order tectonic units is outlined and its correlation with the International Chronostratigraphic Scale is given. Presently used criteria for definition of the Kazakh Ordovician regional stages is critically discussed and revaluated. The archipelago model is considered as most appropriate for reconstruction of the relative position of inferred Kazakh volcanic island arcs and microcontinents in the Ordovician Period. A biogeographical assessment of Kazakh Ordovician benthic faunas suggests strongest affinity to the contemporaneous faunas of Tarim, South and North China and in less degree to the Australian sector of Gondwana, while biogeographical connections with Siberia and Baltica were negligible. During the Sandbian to Katian, a loose cluster of Kazakh microcontinents and island arcs became a major biodiversity hotspot and species pump located in low latitudes on both sides of the equator. Radiolarian cherts from accretionary complexes preserved an almost complete record of biogenic sedimentation for at least 30 Ma from the Furongian to Darriwilian, providing a unique opportunity to study biotas and environments in Ordovician oceans.
... , but Isotelus romanovskyiWeber, 1948 was transferred to Damiraspis Ghobadi Pour & Popov in Ghobadi Pour et al., 2009by Ghobadi Pour et al. (2011b and I. levisChugaeva, 1958 was transferred to Basilicus (Basiliella)Kobayashi, 1934by Zhou & Zhou (2006.Material. Ten cranidia (PMU 30294/3 à , 30297/11 à , 30301/5 à , 30301/8 à , 30302/4 à , 30312/2 à , 30323/5, 30326/12, 30326/18, 30332/42), four librigenae (PMU 30297/4 à , 30301/4 à , 30301/10 à , 30326/19), two hypostomes (PMU 30296/1 à , 30301/2 à ) and 12 pygidia (PMU 30292/4 à , 30293/8 à , 30293/9 à , 30305 à , 30308/ 1 à , 30318/1 à , 30323/6, 30325/2, 30326/15, 30327/1, 30327/31, 30332/43), from the Barkov Formation in the ravines M1 (marked with an à in the list above) and M2 ...
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Ordovician trilobites from the important sequences of the Taimyr Peninsula, Arctic Russia have been poorly studied since the work by Balashova (1959 Balashova, E. A. 1959. Middle and Upper Ordovician and Lower Silurian trilobites of eastern Taimyr and their stratigraphic significance. Sbornik Statej po Paleontologii i Biostratigrafii, 14, 17–47, 6 pls. [In Russian.] [Google Scholar], 1960 Balashova, E. A. 1960. Trilobites of the Middle and Upper Ordovician and Lower Silurian of eastern Taimyr. Leningrad University Publishing House, 111 pp., 6 pls. [In Russian.] [Google Scholar]). Newly collected and well-preserved specimens from Late Ordovician sections, along with the original collections of Balashova, form the basis of a reappraisal of 56 Upper Ordovician (Sandbian–Katian) trilobites. New species include Bronteopsis tenuirhachis, Dionide trigintasegmentata, Failleana superba, Pararemopleurides ornatissimus, Raymondella plastron, Robergia subtilis and R. nikolaiseni. Probable new species include: Stenopareia sp. aff. S. glaber, and Stygina sp. aff. S. latifrons. A new subgenus Bilobaspis of the monorakine genus Evenkaspis, and a new species, Evenkaspis (Bilobaspis) mirabilis, are proposed. Thoracic segments and pygidium are correctly associated for the first time with cephala of the hitherto poorly understood Taimyraspis. The genera Effnaspis and Yumenaspis are likely junior synonyms of Taimyraspis. A placement within the Ityophoridae is suggested for Taimyraspis, together with the closely related genera Ityophorus and Frognaspis. Comparison of Goldillaenoides taimyricus with Failleana suggests that these are also closely related. A provisional placement of the former in the Styginidae is adopted. Bronteopsis nannus Balashova could be a juvenile B. tenuirhachis, and is regarded as a nomen dubium. The genus Ceratevenkaspis dominates among the monorakines on Taimyr, while Monorakos itself has not been collected. Robergia nikolaiseni has a narrow cranidial border, which is also present in the type species of Robergia. Two biofacies are identified in the current collections. The first, the raphiophorid association, is widespread around low latitude Ordovician palaeocontinents, identifying marginal shelf sites; the association is not critical in defining palaeocontinents themselves. Inner shelf faunas of the monorakine-cheirurid-illaenid association have taxa that comprise a distinctive group with a strong link between Taimyr and the Ordovician Siberian craton. The trilobites described herein support reconstructions showing Taimyr peripheral to the Siberian craton during the Ordovician. http://zoobank.org/urn:lsid:zoobank.org:pub:6700871A-2DB6-452F-9B91-7D5AC47EA7F8
Article
A new late Katian (Late Ordovician) trilobite association is documented from the Daduhe Formation in Zhenxiong, northeastern Yunnan, including 17 species of 15 genera, among which four species (Malongullia sinensis, M. zhenxiongensis, Taklamakania paucisegmentatus and Amphitryon constrictus) are new. Lithologic and faunal evidence enables the recognition of a new association with medium diversity, named the Taklamakania Association. It is a typical representative of the Raphiophorid Community that lived in a deep subtidal environment close to the anoxic basin. A total of five trilobite ecological associations were found to occur in South China during the late Katian, in relation to the environmental gradients ranging from shallow subtidal zone, deep subtidal zone, slope to dysoxic shaly basin.
Article
Two trilobite faunas of Late Ordovician (Katian) age are described from the Mayatas Formation in the Stepnyak region of north-central Kazakhstan. The older, oligotaxic fauna derives from flanks of a carbonate build-up, and is dominated by numerous Sphaerexochus specimens. Amphilichas is also relatively common, with Pliomerina and indeterminate asaphids present as rare components. The overlying unit of siliceous argillites contains a different assemblage, representing the raphiophorid biofacies and comprising seven genera. The poorly preserved fauna is dominated by blind trilobites (a new genus of trinucleid, the three-segmented raphiophorid Pseudampyxina , Malongullia ?, Lonchodomas and Arthrorhachis ) and at least two species of large-eyed Telephina , suggesting that they occupied the disphotic zone in deep water offshore. A single cranidium of the odontopleurid Primaspis is also present. The trinucleid, Iputaspis stepnyakensis gen. et sp. nov., has an unusual pit arrangement, with E 1 and E 2 aligned in sulci and all I arcs irregularly arranged. The Atansor area is located within the Stepnyak tectonostratigraphical unit, which probably represented an Ordovician active margin of the Kalmykkol–Kokchetav Microplate. Some of the genera represented in the faunas have affinities with Australia and South China and, also, there is a possible link to European peri-Gondwana.
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The Kokchctav subduction-collision zone (KSCZ) hosting UHP-HP rocks underwent a multistage Vendian-Early Ordovician geodynamic evolution. The subduction of the Palcoasian oceanic lithosphere bearing blocks of continental crust and the collision of the Kokchetav microcontinent with the Vendian-Cambrian island-arc system ultimately governed the formation and exhumation of UHP-HP rocks. In the Vendian-Early Cambrian, the margin of the Kokchetav microcontinent deeply subsided into the subduction zone (150-200 km), which led to UHP-HP metamorphism (the maximum at about 535 Ma) and partial melting of its rocks. At the next stage (535-528 Ma), the generated acid melts including blocks of UHP-HP rocks first quickly, at a rate of 1 m/year, ascended to depths of 90 km for 1 Myr. During subsequent 5 Myr, the UHP-HP rocks ascending at a rate of 0.6-1 cm/year reached the base of the accretionary prism (depths of 60-30 km). Then, in the period from 528 to 500 Ma, the UHP-HP rocks ascended along the faulting structures of the lower crust as a result of wedging of the subduction zone of the Kokchetav microcontinent. During the period from 500 to 480 Ma, the UHP-HP rocks became part of the upper crust. This process led to the formation of the KSCZ, which comprises terranes of the Vendian-Early Arenigian subduction zone occurring at different depths, separated by zones of garnet-mica and micaceous schists, blastomylonites, and mylonites. In the same period, there was an overjump of the subduction zone, which led to the formation of the Ordovician Stepnyak island arc. As a result of the Late Arenigian-Early Caradocian microcontinent-island arc collisions (480-460 Ma), the KSCZ overrided upon the fore-arc trough of the Stepnyak island arc to form a thick accretion-collision orogen. which, having experienced anatectic melting, was intruded by collisional granites of the Zerenda complex 460-440 Ma in age.
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A trilobite assemblage of late Darriwilian age is described from the northern Betpak-Dala Desert, central Kazakhstan. The fauna consists of a number of new taxa including the illaenid Alperillaenus intermedius gen. et sp. nov., the asaphids Damiraspis margiana gen. et sp. nov., and Farasaphus singularis gen. et sp. nov., along with representatives of the genera Ceraurinella?, Pliomerina, Eorobergia and Sphaerexochus. The composition of the assemblage approaches the globally recognised asaphid-illaenid biofacies characteristic of the Benthic Assemblage Zone 2. This fauna is distinct from contemporaneous trilobite associations of South China, but shows some similarity to Late Ordovician (Eastonian) trilobite faunas from New South Wales, Australia.
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Two trilobite faunas of late Ordovician (Sandbian and Katian) age are described from the siliciclastic Karagach Formation, western Tarbagatai Range, eastern Kazakhstan. They comprise 15 families and 24 genera and include the new taxa Agerina acutilimbata sp. nov., Birmanites akchiensis sp. nov., Dulanaspis karagachensis sp. nov. and Kimakaspis kovalevskyi gen. et sp. nov. Most of the Karagach Formation yields graptolites characteristic of the Diplograptus foliaceus [multidens] Biozone, which are associated with the older trilobite fauna; the uppermost part, which is the source of the younger trilobite fauna, contains Orthograptus quadrimucronatus and Dicranograptus hians which suggest a younger age, equating with the lowermost Ensigraptus caudatus Biozone, and the base of the Katian Stage. Most of the trilobite genera in both faunas have a wide geographical distribution in the late Ordovician, although Dulanaspis and Sinocybele are characteristic of low latitude eastern peri-Gondwanan faunas.
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Two separate tectonic blocks in the southwestern segment of the Kazakhstanian orogen, the Chu-Ili terrane and the Karatau-Naryn terrane (with particular attention to Malyi Karatau), are selected to illustrate their geological history and major biogeographical signatures from the Cambrian to the early Silurian. Mid-to Late Ordovician brachiopod and trilobite faunas of Chu-Ili show increased endemicity of shallow shelf assemblages, whereas distinct links to equatorial ('east') peri-Gondwanan are more evident in trilobite assemblages of the outer shelf. In the Late Ordovician, strong biogeographical affinities to equatorial Gondwanan faunas became firmly established and they are also traceable into the Silurian. Early Cambrian faunas of Malyi Karatau show remarkable similarity to those of South China. From the Middle Cambrian this region evolved as an isolated carbonate seamount, but until the Early Ordovician links to South China faunas were still evident. Benthic faunas from both regions show weak links to contemporaneous faunas of Baltica and little in common with Cambrian and Ordovician faunas of the Siberian craton. This suggests their location in low southern latitudes, in relative proximity to East Gondwana, which places some constraints on plate-tectonic reconstructions in relation to the southern cluster of Kazakhstanian terranes, including Karatau-Naryn, North Tien Shan and Chu-Ili.
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The Central Asian Orogenic Belt (c. 1000-250 Ma) formed by accretion of island arcs, ophiolites, oceanic islands, seamounts, accretionary wedges, oceanic plateaux and microcontinents in a manner comparable with that of circum-Pacific Mesozoic- Cenozoic accretionary orogens. Palaeomagnetic and palaeofloral data indicate that early accretion (Vendian-Ordovician) took place when Baltica and Siberia were separated by a wide ocean. Island arcs and Precambrian microcontinents accreted to the active margins of the two continents or amalgamated in an oceanic setting (as in Kazakhstan) by roll-back and collision, forming a huge accretionary collage. The Palaeo-Asian Ocean closed in the Permian with formation of the Solonker suture. We evaluate contrasting tectonic models for the evolution of the orogenic belt. Current information provides little support for the main tenets of the one- or three-arc Kipchak model; current data suggest that an archipelago-type (Indonesian) model is more viable. Some diagnostic features of ridge-trench interaction are present in the Central Asian orogen (e.g. granites, adakites, boninites, near-trench magmatism, Alaskan-type mafic-ultramafic complexes, high-temperature metamorphic belts that prograde rapidly from low-grade belts, rhyolitic ash-fall tuffs). They offer a promising perspective for future investigations.
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The discreteness or otherwise of major Ordovician and Silurian terranes can be recognised by the shallow-water benthic faunas which lived upon them. Their borders are often indicated by the disposition of progressively shallow- to deep-water assemblages at the terrane edge as well as by structural features. Their positions relative to each other in the Early Palaeozoic can be best indicated by a combination of palaeomagnetic and faunal evaluation: the latter is the topic of this paper. Faunal evaluation is now possible quantitatively as well as quantitatively. Global palaeobiogeography is reviewed for the period as deduced from faunal evidence. There was one supercontinent, Gondwana, which stretched from West Gondwana (today's southern Europe and North Africa) at high latitudes to tropical East Gondwana (Australasia and adjacent areas), with intermediate palaeolatitudes in the Middle East and South America. Around Gondwana, especially to its north, were a large number of peri-Gondwanan terranes, particularly Avalonia, Perunica, parts of Turkey and Arabia and Sibumasu. In addition, there were the substantial independent continents of Laurentia, Baltica, Siberia, Annamia, North China and South China. Analysis of the shallow-water benthos, particularly trilobites and brachiopods, provides distinctive signatures for palaeo-position in most cases. Despite a large faunal turnover particularly corresponding with the latest Ordovician glacial event, the progressive evolution of the ecologies of benthic shelly faunas were also much influenced by changing geographies during the 80-Ma period. In the early Ordovician, oceans were at their widest, enabling Baltica and Laurentia to have different signatures from either East or West Gondwana. Siberia in early Ordovician times had faunal contact with Laurentia and East Gondwana, but in the mid-Ordovician, there were more endemics, and by the late Silurian, it was the only continent of substance in the northern hemisphere (hosting the Tuvaella Fauna). South China has varied faunal links but seems best treated as at the edge of the peri-Gondwanan collage for most of the period. We show how faunas document the early Ordovician rift of Avalonia from West Gondwana and its movement and subsequent collisions, first with Baltica in the end Ordovician and then with Laurentia in the early Silurian. Faunas also support the postulated movement of the Precordillera of South America from Laurentia in the early Ordovician to intermediate- to high-latitude Gondwana in the Silurian. We examine peripheral terranes bordering Iapetus to demonstrate their pre-collision positions. Analysis of some of the many terranes now forming Kazakhstan and adjacent areas in central Asia today reveals that the benthic faunas there have more affinity with Gondwanan and peri-Gondwanan faunas than with Baltica or Siberia, and thereby challenge structural models postulating an Early Palaeozoic Kipchak arc.
Oceanography in the Ordovician Advances in Ordovician Geology
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Wilde, P. 1991. Oceanography in the Ordovician. In C.R. Barnes and S.H. Williams (eds.), Advances in Ordovician Geology. Geological Survey of Canada, Paper 90, 283-298