Malyi Karatau Research Articles

Early Neoproterozoic fore-arc basin strata of the Malyi Karatau Range (South Kazakhstan): Depositional ages, provenance and implications for reconstructions of Precambrian continents

Multidisciplinary geochronological, isotopic, chemical, and facial studies in the Malyi Karatau Range (MK) of South Kazakhstan elucidate the Precambrian stratigraphic framework and evolution of the Ishim Middle Tianshan microcontinent (IMT) in the western Central Asian Orogenic Belt. Detrital zircon and apatite U-Pb ages for siliciclastic rocks and chemostratigraphic Sr-C isotopic data for carbonates indicate that they deposited during 800–730 Ma. The sediments are dominated by deeper marine facies in the southwest and shallow marine facies in the northeast. According to paleocurrent indicators, the main provenance located to the west of the basin. Based on the detrital zircon age spectra, the source terrane represented a Paleoproterozoic to Archean crustal block, reworked by an early Neoproterozoic c. 850–720 Ma continental arc. Erosion of Archean and Paleoproterozoic crust is also evidenced by negative εNd values for the sandstones. The petrographic and chemical compositions of the sandstones are consistent with a continental arc source; however anomalously high concentrations of chromium in some layers point to the presence of ultramafic rocks in the source terrane. The ages of metamorphic zircons indicate a high-grade metamorphic event at provenance at c. 2.0 Ga and the ages of detrital apatites suggest a reset of U-Pb isotope system in apatite at c. 1.8–1.9 Ga. In the early Neoproterozoic, the MK located between the continental arc in the west and the oceanic basin in the east and represented a fore-arc basin. The similarity of the Precambrian magmatic and metamorphic histories and sedimentary facies indicates that the IMT, the Tarim and Yangtze cratons constituted a single Precambrian Ulutau-Tarim-Yangtze Continent (UTY). Judging from the ages of continental arcs that evolved on the northern and southern sides of the UTY, it represented an independent continent at c. 950–840 Ma and was incorporated in Rodinia at c. 830–820 Ma.

Siliceous sponge expansion and phosphogenesis in a shallow water environment in the Malyi Karatau Range (Kazakhstan) during the Precambrian-Cambrian transition

Ocean oxygenation during the Precambrian-Cambrian transition is thought to be one of the key factors for the rapid diversification of animals, known as the ‘Cambrian Explosion’. Siliceous sponges inhabiting continental slope settings were capable of shifting the respiratory oxygen demand in the water column to depth, resulting in an increase in oxygen levels of shallow water. To assess the global importance of the impact of ecosystem engineering by sponges, we evaluated the palaeo-environmental conditions that confine sponge expansion using multiple geochemical proxies including silicon and carbon stable isotopes as well as major- and trace elements in cherts and siliceous sedimentary rocks that were deposited in shallow water around the Precambrian-Cambrian transition. We investigated three lithosections in the Malyi Karatau Range in southern Kazakhstan. The lowermost chert samples of these sections are typically characterized by comparably low δ30Si values and exhibit molds of siliceous sponge spicules. Upsection the occurrence of cross-bedding structures and granular phosphorites document the shallowing of the depositional environment, where overall increasing δ30Si values and increasing Al/Si indicate less settlement of sponges and higher suspended particle loads. Corresponding carbon isotope records of the carbonate fraction decrease from near-zero to negative carbon isotope values averaging −5.9‰. The δ13Ccarb values overall coincide with Y/Ho, the redox indicator Ce/Ce*, and mass fractions of carbonate fluorapatite, suggesting that these ratios are predominantly controlled by the mineralization of organic matter in phosphatic sediment. The studied sections document the ecological requirements for sponge settlement and proliferation, such as the presence of a hard substrate and sufficiently low suspended particle concentrations and/or low wave energy. This work suggests that the widespread appearance of karsted surfaces around the Precambrian-Cambrian transition that were subsequently submerged during the Cambrian transgression would have created permissive habitats for sponges and large phosphate deposits. The capability of sponges to oxygenate shallow seawater and extensive phosphorous burial in epicontinental basins are thus feasible mechanisms for the seawater oxygenation around the Precambrian-Cambrian transition.

The oldest ‘Lingulellotreta’ (Lingulata, Brachiopoda) from China and its phylogenetic significance: integrating new material from the Cambrian Stage 3–4 Lagerstätten in eastern Yunnan, South China

The origin of Cambrian brachiopods and their phylogenetic relationship with other lophotrochozoans is far from clear. Lingulellotretidae, the oldest family of lingulate brachiopods, is typified by possessing a pouch-like coelomic extension beyond the hinge line, subtended in a triangular pseudointerarea. The early Cambrian (Stage 4) linguloid brachiopod – originally described as ‘Lingulepis’ malongensis Rong, and later referred to Lingulellotreta within the Family Lingulellotretidae – is here redescribed and assigned to Eoobolus within the Family Eoobolidae, based on new exceptionally preserved topotype material from the type locality, part of the Guanshan Lagerstätte (Wulongqing Formation), Kunming–Malong area, eastern Yunnan, South China. For the first time, we provide a record of the soft anatomy, including a pedicle for the cosmopolitan genus Eoobolus. Due to loss of the type specimen, a neotype of E. malongensis is selected. Differing from the Guanshan E. malongensis, the Chengjiang species is slightly bigger in shell size, and possesses an elongated ventral pseudointerarea. In addition, new flattened specimens of ‘Lingulellotreta malongensis’ from the Chengjiang (Stage 3) biota, preserved in lateral and dorsoventral views, demonstrate an interior lophophore organization and a well-developed pedicle foramen, typical of the genus Lingulellotreta. When compared to the type species – Lingulellotreta ergalievi Koneva – from the Shabakty Group (Cambrian Stage 4), Malyi Karatau Range, Kazakhstan, the Chengjiang species possessed a more elongated ventral pseudointerarea, accommodating an extended body cavity, deepening posteriorly, with a recurved digestive tract. Accordingly, the Chengjiang specimens are thus referred to a new species, Lingulellotreta yuanshanensis sp. nov. The elongated, tubular extended body cavity of Lingulellotreta, which is not present in the slightly younger Guanshan Eoobolus, has recently gained further phylogenetic significance, as support continues to emerge for the view that a ‘tubular’ body plan may be primitive within the lophotrochozoans, notably brachiopods.http://zoobank.org/urn:lsid:zoobank.org.pub:B3212125-F671-4B88-82C5-40C37B5C1631:

Radiogenic Sr and Stable C and O Isotopes Across Precambrian‐Cambrian Transition in Marine Carbonatic Phosphorites of Malyi Karatau (Kazakhstan)—Implications for Paleo‐environmental Change

AbstractThe Precambrian‐Cambrian (PЄ‐Є) transition is a unique period in Earth's history known for the “Cambrian Explosion.” Here we present a continuous radiogenic and stable isotope (87Sr/86Sr, δ13CVPDB, carb, and δ18OVPDB, carb) and elemental (including rare earth elements) record across the PЄ‐Є transition, preserved in phosphatic and carbonate shallow‐water deposits from two sections (Koksu and Kyrshabakty) in Kazakhstan. Microstructure, trace, and rare earth elements concentrations reflect near‐primary preservation. δ13CVPDB, carb data (−12.1‰ to 3.3‰) record formation conditions at a time of severe geodynamic changes. Negative δ13CVPDB, carb at the PЄ‐Є boundary resemble the Basal Cambrian Carbon Anomaly. Average δ18OVPDB, carb values of −11.7 ± 3.8‰ are suggested to represent near‐primary signals and can be explained by isotopically lighter past sea water and elevated temperature during precipitation compared to present‐day conditions. Initial 87Sr/86Sr of the carbonate and phosphate fraction are in the range of 0.7086–0.7112 at the Koksu section and 0.7082–0.7136 at the Kyrshabakty section. This is in general agreement with the seawater 87Sr/86Sr evolution during the Early Cambrian. In this study, we present a refined 87Sr/86Sr seawater evolution, highlighting an extreme positive Sr isotope excursion at the PЄ‐Є transition, which is suggested to be indicative for enhanced continental weathering and an increase in nutrient runoff into shallow ocean waters. This extreme geodynamic event may have served as a driving force for enhanced biologic activity in the lead up to the Cambrian Explosion, where phosphatic shallow‐water deposits from Kazakhstan constitute a valuable paleo‐environmental archive.

Reconstruction of the paleostress field of the Kokdjot Block, Malyi Karatau ridge (South Kazakhstan)

Reconstruction of the paleostress field of the Kokdjot Block, Malyi Karatau ridge (South Kazakhstan) was done as a result of the detailed structural study. Kink-bands and fold-axes were used for indicate stress field reconstruction. Study areas of the Kokdjot Block are located from the northwest to the southeast of the Kokdjot plateau and are characterized as both clastic sedimentary rocks of greenschist and phyllite facies of metamorphism and clastic and carbonates sedimentary rocks. Two stress fields have been identified as corresponding to Caledonian (Late Ordovician) and Hercynian deformations. The earlier tectonic event is characterized by horizontal compression of the northeastern trend and later tectonic event is characterized by the shear stress field at the west-north-west trend of the compression axis.

New Data on the Age of Detrital Zircons from the Kokdjot Group and Bolshekaroi Formation, Malyi Karatau (Southern Kazakhstan)

U–Pb dating of detrital zircon from the Kokdjot Group and Bolshekaroi Formation (Malyi Karatau) yielded for all the samples age clusters at about 800–805, 855–890, 1980–2100, and 2440–2470 Ma. The Kolmogorov–Smirnov test suggests they have identical provenance sources. The Kokdjot Group and Bolshekaroi Formation ages are presumably Neoproterozoic, not older than 800 Ma, though a somewhat younger age (not older 770 Ma) cannot be ruled out.

The Auxiliary boundary Stratotype Section and Point (ASSP) of the Jiangshanian Stage (Cambrian: Furongian Series) in the Kyrshabakty section, Kazakhstan

The Kyrshabakty section in the Malyi Karatau Range, southern Kazakhstan, has been approved as the Auxiliary boundary Stratotype Section and Point (ASSP) for the base of the Jiangshanian Stage of the Furongian Series (Cambrian System). The first appearance datum (FAD) of the agnostoid trilobite Agnostotes orientalis coincides with the horizon marking the base of the Jiangshanian Stage, and the FAD of A. orientalis occurs at 259.0 m in the measured section, 61.2 m above the base of Unit 8 in the Zhumabai Formation. The boundary interval in the Kyshabakty section shows a relatively monotonous succession of carbonate deposits. The section contains an abundance of Cambrian fossils including diverse trilobites, brachiopods, molluscs, bradoriids, protoconodonts and paraconodonts.

Large-Scale Seismogenic Deformation of A Carbonate Platform Straddling the Precambrian-Cambrian Boundary, Karatau Range, Kazakhstan

Abstract The Berkuty Member of the Ediacaran Kyrshabakty Formation in the Malyi Karatau Mountains of southern Kazakhstan immediately underlies some of the world's largest sedimentary phosphate deposits of earliest Cambrian age. This 5–30 m thick unit, exposed over > 40 km strike length, is a complex carbonate unit that was formed by regional seismic deformation of semiconsolidated carbonate. Three subdivisions are recognized. The lower unit (Unit 1), ∼ 3–5 m thick, is regionally shortened by meter-scale flexural folds, and shows thrusting and imbrication of underlying siliciclastic units; local extension is accommodated by soft-sediment boudinage. The middle unit (Unit 2), ∼ 2–5 m thick, consists largely of a megabreccia of angular to subrounded dolomite clasts up to a meter across. The upper unit (Unit 3), up to 3 m thick, consists of microbially laminated dolobindstone, dolorudstone, and flat-pebble conglomerate, cut by syndepositional, low-angle normal faults. Channelization and bank-margin slumping at the top of Unit 3 was followed by karsting, prior to the formation of a high-energy, shallow-water, carbonate–phosphatic coastal environment. We interpret the Berkuty Member as an example of an incompletely and unevenly lithified carbonate platform deformed by at least one large seismic event (Mb greater than approximately 8). Deformation of the lower unit included local sliding, imbrication, and folding, whereas the middle unit was deformed by in-situ disaggregation due to extensive shaking. Regional coseismic or early postseismic uplift of soft sediment, possibly above sea level, led to widespread gravitational collapse, rapid drainage incision, and drainage fill by bank collapse and conglomeratic wedges. While each of the deformational features and stratigraphic elements observed in this unit is not diagnostic of a seismogenic origin, the remarkable lateral extent in outcrop, the wide range of structures related to soft-sediment deformation, their systematic lateral variability, and the internal process-related stratigraphy demonstrates in an exemplary way the manner in which single soft-sediment deformation events can produce a large array of features over a broad area, largely due to minor rheological differences.

First report of a Meishucun-type early Cambrian (Stage 2) ichnofauna from the Malyi Karatau area (SE Kazakhstan): Palaeoichnological, palaeoecological and palaeogeographical implications

A trace fossil assemblage from the early Cambrian phosphorites of the Aktugai and Koksu sections (Chulaktau Formation) of the Lesser Karatau area (= Malyi Karatau in the following text) in SE Kazakhstan is reported for the first time. Based on a rich and biostratigraphically significant Small Shelly Fossil (SSF) record, the ichnofauna can be attributed to the basal Cambrian (Terreneuvian: ?uppermost Fortunian to Stage 2).Along with rare vertical burrows, the ichnoassemblage yielded abundant simple worm-shaped epi- and infaunal burrows of various ichnotaxa being associated with branched traces and (pre-trilobitic) arthropod traces.The non-arthropod ichnofauna consists of hyporeliefs of large straight to slightly meandering traces belonging to Palaeophycus isp., and Psammichnites isp. type traces. This ichnofauna is accompanied by horizons with short inclined U-shaped burrows of the Planolites-type. The evidence of Treptichnus pedum-like simple branching (sub-) horizontal traces is proved for the Koksu section but remains problematic for the Aktugai section as they are poorly preserved and could be mixed up with Planolites-type traces. Additionally, a dark-brown coloured phosphoritic sandy dolostone band close to an iron- manganese rich stromatolite bed on the base of the Ushbas Member contains vertical funnel-shaped burrows of more than a decimetre in length which could be attributed to dwelling burrows of infaunal lingulid brachiopods (?Lingulichnus). Several short and larger (knob-shaped) vertical burrows in the surrounding phosphoritic dolostones occasionally display faintly preserved radial running and distally branching probes. They resemble star-shaped trace fossils from the Meishucun- and from the younger (Cambrian Stage 4) Guanshan sections of South China.The arthropod traces can be attributed to Rusophycus-type traces (probably R. avalonensis) as well as to Monomorphichnus-type and problematic primitive (?) Cruziana-type trackways. The arthropod traces are concentrated in the massive phosphorites of the Karatau Member (Upper Chulaktau Formation) of the Aktugai-I and the Koksu localities. Some of them are preserved as positive hyporeliefs on the subsurface of an overlaying greenish-grey coloured chert band (panel A of the fourth figure in this article).The ichnotaxonomic inventory, the facies, the lithology and the depositional regime of the hosting rocks as well as the trace preservation in the massive phosphorites resemble the situation in the some older (Fortunian Stage) Meishucun ichnofauna of southern Yunnan, South Chinese Yangtze Platform as well as in some aspects the ichnoassemblage from the much younger (Stage 4) Wulongqing Formation of Yunnan. The here reported type of early Cambrian ichnofauna could be characteristic for the abundant basal Cambrian phosphorite-dominated shelf deposits on the northwestern realm of Gondwana.

Pseudagnostus rugosusErgaliev, 1980: a key agnostoid species for intercontinental correlation of upper Furongian (Cambrian) strata

AbstractPseudagnostus rugosusErgaliev, 1980 is described from the FurongianCtenopyge tumidaZone at Gislövshammar, Scania, southern Sweden. This is the first record of this distinctive agnostoid in Scandinavia. The species is known previously from Malyi Karatau, Kazakhstan, and northwestern Hunan and western Zhejiang, South China, and provides a newly recognized link between middle–upper Furongian successions in Baltica, Kazakhstan and South China. The occurrences ofP. rugosusallow a correlation between theC. tumidaZone of Baltica, the lowerEolotagnostus scrobicularis–JegorovaiaZone of Kazakhstan and the lowerLotagnostus americanusZone of South China.

Gondwanan faunal signatures from Early Palaeozoic terranes of Kazakhstan and Central Asia: evidence and tectonic implications

Abstract 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.

THE OLDEST-KNOWN METAZOAN PARASITE?

A unique specimen of the micromorphic fossil lingulate (organophosphatic-shelled) brachiopod Linnarssonia constans Koneva, 1983 from the late Lower Cambrian Shabakty Group of the Malyi Karatau Range in Kazakhstan, Central Asia, preserves evidence of infestation within the mantle cavity by a vermiform animal, leading to the growth of an internal tubular protuberance (Fig. 1) resulting from symbiosis some 520 million years ago. Examples of symbiotic relationships between metazoans in the early Paleozoic are sparse (Conway Morris, 1981, 1990; Conway Morris and Crompton, 1982). Descriptions of a variety of galls and tumorlike swellings in some trilobites extend records back to the Middle Cambrian (Conway Morris, 1990), but their interpretation as traces of endoparasitic activity remains somewhat speculative. Thus galllike swellings on the stems of Silurian echinoderms (Franzen, 1974), vermiform tubes on some early Ordovician dendroid graptolites (Conway Morris, 1990), and various tubes and blisters on graptoloid graptolites (see Bates and Loydell, 2000 for review) are among the hitherto earliest known convincing records of host-parasite relationships within metazoans. Our example reported here predates the oldest of these previous records by approximately 35 to 40 million years, and demonstrates that symbiosis involving complex adaptations (e.g., larval settlement on or within living tissue and exploitation of feeding systems of the host) and codependent life cycles were already established soon after the ‘explosive’ evolutionary radiation of marine metazoans in the early Cambrian. The fossil evidence of infestation on lophophorates is especially sparse, at best. The oldest hitherto undoubted records are both from brachiopods of Devonian age, in the Lower Devonian Emsian Stage of eastern Australia and in the Middle Devonian Givetian Stage of the Holy Cross Mountains in Poland, respectively.

The oldest-known metazoan parasite?

A unique specimen of the micromorphic fossil lingulate (organophosphatic-shelled) brachiopod Linnarssonia constans Koneva, 1983 from the late Lower Cambrian Shabakty Group of the Malyi Karatau Range in Kazakhstan, Central Asia, preserves evidence of infestation within the mantle cavity by a vermiform animal, leading to the growth of an internal tubular protuberance (Fig. 1) resulting from symbiosis some 520 million years ago. Examples of symbiotic relationships between metazoans in the early Paleozoic are sparse (Conway Morris, 1981, 1990; Conway Morris and Crompton, 1982). Descriptions of a variety of galls and tumorlike swellings in some trilobites extend records back to the Middle Cambrian (Conway Morris, 1990), but their interpretation as traces of endoparasitic activity remains somewhat speculative. Thus galllike swellings on the stems of Silurian echinoderms (Franzen, 1974), vermiform tubes on some early Ordovician dendroid graptolites (Conway Morris, 1990), and various tubes and blisters on graptoloid graptolites (see Bates and Loydell, 2000 for review) are among the hitherto earliest known convincing records of host-parasite relationships within metazoans. Our example reported here predates the oldest of these previous records by approximately 35 to 40 million years, and demonstrates that symbiosis involving complex adaptations (e.g., larval settlement on or within living tissue and exploitation of feeding systems of the host) and codependent life cycles were already established soon after the ‘explosive’ evolutionary radiation of marine metazoans in the early Cambrian. The fossil evidence of infestation on lophophorates is especially sparse, at best. The oldest hitherto undoubted records are both from brachiopods of Devonian age, in the Lower Devonian Emsian Stage of eastern Australia and in the Middle Devonian Givetian Stage of the Holy Cross Mountains in Poland, respectively.

Early Cambrian lobopodian sclerites and associated fossils from Kazakhstan

A low diversity fossil assemblage dominated by Mongolitubulus spines, from the Early Cambrian Geres Member of the Shabakhty Formation at Koksu, Malyi Karatau, Kazakhstan, enables identification of its sclerite variability within the scleritome. No other sclerotised structures could be matched with the spines, indicating that these were the only sclerotised part of the body and were periodically shed. The prominent spines of Mongolitubulus have a scale–like external ornamentation and fibrous internal structure. Possibly they armed the body of a lobopodian similar to Xenusion. The Mongolitubulus spines belong to a series of Cambrian phosphatic fossils, the other end members of which are sclerites of Microdictyon, the second most abundant component of the Koksu assemblage. The latter superficially resemble schizochroal trilobite eyes, but in life covered the dorso–lateral sides of the body segments, as is evident from complete specimens from the Chinese Chengjiang locality. A pair of sclerites of Microdictyon, representing uncompleted exuviation, from Koksu show that each hole originally contained a non–phosphatised lenticular body. This makes a compound eye nature of the Microdictyon sclerites likely, and even their homology with arthropod eyes cannot be excluded.

LINGULATE BRACHIOPODS FROM THE CAMBRIAN-ORDOVICIAN BOUNDARY BEDS OF UTAH

Seven genera and eight species of lingulate brachiopods are described from the Cambrian-Ordovician boundary beds (Cambrooistodus minutus Conodont Subzone to Rossodus manitouensis Conodont Zone) at the Lawson Cove and Lava Dam North sections, Ibex area, Utah, USA. The fauna includes one new linguloid genus, Wahwahlingula, and four new species, Lingulella? incurvata, Zhanatella utahensis, Conotreta millardensis, and Quadrisonia? lavadamensis. Lingulate brachiopods from this interval are very poorly known from Laurentia, but the recorded fauna is very similar to that described from coeval beds at Malyi Karatau, Kazakhstan, and both areas contain Eurytreta cf. bisecta (Matthew, 1901); E. sublata Popov, 1988; Zhanatella Koneva, 1986; Schizambon Walcott, 1889; and Wahwahlingula. Eurytreta cf. bisecta is also known from the Lower Ordovician of Avalonian Canada, Britain, and Scandinavia.

Lingulate brachiopods from the Cambrian-Ordovician boundary beds of Utah

Seven genera and eight species of lingulate brachiopods are described from the Cambrian-Ordovician boundary beds (Cambrooistodus minutus Conodont Subzone to Rossodus manitouensis Conodont Zone) at the Lawson Cove and Lava Dam North sections, Ibex area, Utah, USA. The fauna includes one new linguloid genus, Wahwahlingula, and four new species, Lingulella? incurvata, Zhanatella utahensis, Conotreta millardensis, and Quadrisonia? lavadamensis. Lingulate brachiopods from this interval are very poorly known from Laurentia, but the recorded fauna is very similar to that described from coeval beds at Malyi Karatau, Kazakhstan, and both areas contain Eurytreta cf. bisecta (Matthew, 1901); E. sublata Popov, 1988; Zhanatella Koneva, 1986; Schizambon Walcott, 1889; and Wahwahlingula. Eurytreta cf. bisecta is also known from the Lower Ordovician of Avalonian Canada, Britain, and Scandinavia.

Early Cambrian Lingulellotreta (Lingulata, Brachiopoda) from South Kazakhstan (Malyi Karatau Range) and South China (Eastern Yunnan)

“Lingulepis’ malongensis Rong from the upper part of the Lower Cambrian Chiungchussu Formation of Yunnan is referred to Lingulellotreta Koneva; L. malongensis (=Lingulellotreta ergalievi Koneva) is redescribed on the basis of new material from the Lower Cambrian of south Kazakhstan. It is the earliest known taxon of the Lingulellotretidae, which is unique within the Linguloidea in having an elongate pedicle foramen and internal pedicle tube. The occurrence of Lingulellotreta malongensis in south China is considered usually to be of Atdabanian age, but brachiopod based correlation with south Kazakhstan suggests that a possible Botomian or younger age, for both the upper part of Chiungchussu Formation in Yunnan and the lowermost part of Shabakty Group in the Malyi Karatau Range, is equally plausible.

Middle Ordovician (Llanvirn) ungulate brachiopods and conodonts from the Malyi Karatau Range, Kazakhstan

A new middle Ordovician fauna including conodonts and brachiopods is described from the early Llanvirn Zhyrykaus Formation, Malyi Karatau Range, southern Kazakhstan. The fauna includes the lingulate brachiopodsHyperobolus fragilis n. sp. andTalasotreta apollonovi n. gen. n. sp., as well as the conodontsCordylodus? cf.horridus, Drepanoistodus? sp.,Erraticodon sp.,Parapaltodus simplicissimus, Prioniodus (Baltoniodus) sp.,Protopanderodus cf.varicostatus, andWalliserodus sp. s. f. It represents the first record of Llanvirn conodonts and Ungulate brachiopods from southern Kazakhstan.

Milankovitch Forcing of Cambrian Cyclic Shallow Marine Carbonates of Malyi Karatau Range, Kazakhstan Republic: Preliminary Results of Advanced Time Series Analysis: ABSTRACT

Milankovitch Forcing of Cambrian Cyclic Shallow Marine Carbonates of Malyi Karatau Range, Kazakhstan Republic: Preliminary Results of Advanced Time Series Analysis: ABSTRACT

Biofacies Evidence for Late Cambrian Low-Paleolatitude Oceans, Western United States and Central Asia

Biofacies that formed on carbonate platform-margin slopes adjacent to an early Paleozoic, low-paleolatitude paleoocean are contained in the Upper Cambrian Swarbrick Formation, Tyby Shale, and Upper Cambrian-lowest Ordovician Hales Limestone of the Hot Creek Range, Nevada, and the Upper Cambrian-lowest Ordovician part of the Shabakty Suite of the Malyi Karatau, southern Kazakhstan. These in-situ limestones formed in platform-margin slope and basin-plain environments. Shoal-water faunal assemblages occur in carbonate-turbidite and debris-flow deposits interbedded with in-situ deeper water assemblages of the submarine-fan facies. Abundant sponge spicules, geographically widespread benthic trilobites, and rare ostracodes occur in some of the in-situ beds. In contrast, the shoal-water platform environments were well oxygenated and contain mainly endemic trilobite assemblages. These biofacies characteristics support an interpretation that Late Cambrian oceans were poorly oxygenated, but not anoxic, below the surface mixing layer and that benthic trilobite faunas were widely distributed in response to the more-or-less continuous deep water, low-oxygen habitats. Elements of the Late Cambrian low-oxygen biofacies are widespread in the Tien Shan structural belt of China and the Soviet Union, in central and eastern China, and along the western margin of early Paleozoic North America. This facies distribution pattern defines the transition from low-paleolatitude, shoal-water carbonate platformsmore » to open oceans which have since been destroyed by pre-Late Ordovician and pre-middle Paleozoic Paleotectonic activity.« less