Stratigraphic significance of the Cambrian ichnofauna of the Zanskar region,Ladakh Himalaya,India

The Cambrian succession in the Zanskar Basin of Tethys Himalaya contains an abundant ichnofossils like in the other Tethyan Himalayan successions. The ichnofossils are stratigraphically important as they occur below the trilobite body fossils and are useful to define the basal part of the Cambrian. The ichnofossil assemblage reported from the Zanskar Basin of Ladakh Himalaya is significant to demarcate the Early Cambrian age due to lack of other faunal elements so far. The body fossils of trilobites recorded from the overlying beds indicates the earliest part of the Middle Cambrian age. Sixteen ichnogenera identified include: Bifungites, Cruziana, Diplichnites, Dimorphichnus, Isopodichnus, Lockeia, Merostomichnites; Monomorphichnus, Psammichnites, Palaeophycus, Planolites, Rhizocorallium, Skolithos, Taphrhelminthopsis, Teichichnus, Trepitichnus and trilobite scratch marks etc. The ichnogenera reported so far from this part of the Tethyan Himalayan region belongs mostly to the traces of arthropod origin. The ichnofauna ranges in age from Lower Cambrian to late part of the Middle Cambrian. The ichnofaunal assemblage can be assigned to repichnial, cubichinial, pascichnial, to fodinichnial behaviour. The distribution of ichnofossils in the studied sections shows that the ichnofossils are predominately less in occurrence in the sections were trilobites dominates and higher in the successions the abundance of ichnofossils decreases.     

Cambrian stratigraphy of Kashmir and its boundary problems

The biostratigraphy of the Cambrian of Kashmir based on trilobite assemblage zones and trace fossils has been attempted. Faunal gaps occur in lower part of Lower Cambrian, upper Lower Cambrian, lower Middle Cambrian and upper part of Upper Cambrian. In the Lower Cambrian Cruziana—Rusophycus and Redlichia Zones, in the Middle Cambrian Solenopleura—Tonkinella, Tonkinella—Anomocare, Anomocare—Bailiella and Bolaspidella Zones, and in the Upper Cambrian Chuangia and Dikelocephalites Zones are recognized. The position of intrasystem boundaries is also discussed. While the various taxa have lithological preferences and are not necessarily found in a continuous sequence, an attempt has been made to interpret the ranges of different genera. The affinities of the fauna with that of other Cambrian basins of the world are discussed. It is concluded that the bulk of the fauna is of a cosmopolitan nature.     

Tasmanian Cambrian biostratigraphy—a preliminary report

In Tasmania shelly fossils are known from Middle and Upper Cambrian sediments of the Dundas Trough, Fossey Mountain Trough, Dial Range Trough, Beaconsfield Trough, Smithton Basin, Adamsfield Trough and from within sediments associated with the Mount Read Volcanics of Western Tasmania. In the Dundas Trough fossils range in age from early Middle Cambrian (Ptychagnostus gibbus Zone) to the middle Late Cambrian (pre‐Payntonian A or B). Late Middle Cambrian fossils occur in sediments associated with the Mount Read Volcanics in two places in Western Tasmania. Late Middle Cambrian fossils only are known from the Smithton Basin and the Beaconsfield Trough. Late Middle to early Late Cambrian faunas are known from the Dial Range Trough; the Adamsfield Trough contains middle Middle to middle Late Cambrian fossils. Tasmanian Cambrian faunas show affinities with those of Queensland, China, the northwest Siberian Platform and northern Victoria Land, Antarctica.     

Fossiliferous Cambrian limestone from within the mt read volcanics,mt lyell mine area,Tasmania

In the Mt Lyell area limestone conformably underlying unmineralized Mt Read Volcanics and unconformably overlying mineralized Mt Read Volcanics contains fossils of late Middle Cambrian or early Upper Cambrian age. This suggests an upper limit of late Middle Cambrian or early Upper Cambrian for the mineralization in the Mt Lyell area. The view of Gee et al. (1970) that the Mt Read Volcanics and the fossiliferous Cambrian sequences of western Tasmania are at least partly contemporaneous is confirmed.     

Trace fossils from the cambro-ordovician rocks of North Wales and their stratigraphic significance

In North Wales, Cruziana semplicata (Salter) is recorded from three otherwise unfossiliferous localities and Teichichnus sp. (Seilacher) and Phycodes circinatum (Richter) are shown to be widely distributed within the lower Arenig (Didymograptus extensus zone) sediments. P. circinatum is also recorded from the otherwise unfossiliferous Upper Pennant Quartzite. From a discussion of the stratigraphic ranges of these trace fossils it is suggested that the rocks of the C. semplicata bearing localites are Upper Cambrian (Ffestiniog) in age while the Upper Pennant Quartzite is Ordovician, probably Arenig.     

贵州丹寨南皋地区中寒武统甲劳组的遗迹化石

贵州丹寨南皋是中国南方寒武系典型地层剖面的地区之一.描述了产自中寒武统甲劳组的遗迹化石Chondrites ichnosp., Beaconichnus jiaolaoensis (nov. ichnosp.), Bifungites ichnosp., Diplichnites danzhaiensis (nov. ichnosp.), Monomorphichnus taenia (nov. ichnosp.), Palaeophycus tubularis, Phycodes pedum, Teichichnus rectus, T. palmatu. 对Beaconichnus Gevoers,1973和Qipanshanichnus Luo et Tao,1994进行了对比研究,认为这2个遗迹属为同一遗迹的不同部位,为同义名.甲劳组的遗迹化石组合属Seilacher(1964,1967)的Cruziana遗迹相,其沉积环境应为浪基面之下水动能中等的正常浅海环境.     

Cambrian trace fossils of the Cruziana ichnofacies from the Bikaner-Nagaur Basin,north western Indian Craton

The Marwar Supergroup of the Bikaner-Nagaur Basin is composed of sediments deposited from the late Neoproterozoic (Ediacaran) to Upper Cambrian. The Nagaur Sandstone Formation of the Nagaur Group (uppermost division of the Marwar Supergroup) preserves trace fossils significant for establishing Early Cambrian biostratigraphic zones and depositional facies. Fifteen ichnospecies (and eight ichnogenera) identified in the Nagaur Sandstone Formation include “Treptichnus” pedum, Cruziana cf. tenella, Cruziana isp., Diplichnites ispp. A, B, and C, Gyrophyllites isp., Lockeia isp., Merostomichnites isp., Monomorphichnus gregarius isp. nov., Monomorphichnus isp., Planolites isp., Psammichnites isp., Rusophycus bikanerus isp. nov., Rusophycus cf. carbonarius, Rusophycus isp. and radial trace fossils.These trace fossils belong to ethological categories pascichnia, repichnia, cubichnia, and fodinichnia and represent arthropod and worm-like burrowing biota. The assemblage and a regional comparison with contemporaneous trace fossils in the eastern Gondwanan realm suggest that the sequence in the study area belongs to the Cruziana tenella Ichnozone and to Stage 2 (upper part of Terreneuvian), however the Middle Cambrian is not excluded. The trace fossil assemblage belongs to the archetypal Cruziana ichnofacies. Cross bedded sandstone, mud cracks and rainprints in the ichniferous strata of the Nagaur Sandstone Formation indicate deposition in an intertidal sand flat with channels that was exposed episodically.     

Arenig trace fossils from the Salamanca area,western Spain

Trace fossils are recorded at two localities from the ‘Armorican Quartzite’ (Lower Ordovician) in the Salamanca area, western Spain. Sixteen ichnospecies, belonging to twelve ichnogenera, are described; all ichnospecies occur in the upper part of the unit, only four in the lower part. The ichnogenera comprise Arthrophycus, Cruziana, Daedalus, Didymaulichnus, Diplichnites, Diplocraterion, cf. Gor-. dia, Monomorphichnus, Muensteria, Palaeophycus, Planolites, and Rusophycus. The presence of Cruziana furcifera, C. goldfussi, C. rugosa, and C? cf. imbricata indicate that the upper part of the unit is of Arenig age. The lower part has yielded only the two former ichnospecies and may extend down into the Tremadoc. The species of Cruziana and their stratigraphical significance are discussed.     

The age of the Mt Read Volcanics in the Que River area,western Tasmania

Sediments associated with the Mt Read Volcanics in the Que River area contain fossils that indicate that the Mt Read Volcanics (in part at least) are late Middle Cambrian (Ptychagnostus punctuosus or P. nathorsti Zone) in age, and that they are in part marine. The sediments are defined as the Que River Beds.     

How valid is Cruziana Stratigraphy?

The stratigraphic value of trilobite burrows has recently been questioned because of a seemingly Ordovician form in the Lower Cambrian of Canada. Closer examination shows, however, that the Cambrian homeomorph (Cruziana pectinata n. sp.) has a significantly different scratch pattern. This raises the question whether the multiple scratches of the Ordovician Cruziana rugosa were also made by exopodites or by similarly shaped endopodites.     

峡东寒武纪三叶虫化石新材料

三峡东部中寒武统化石稀少。本文对在宜昌三斗坪中寒武世覃家庙组二段下部含鲕粒灰岩、细晶灰岩中所采获的三叶虫Xingrenaspis sp.进行了研究和描述,并对含化石地层时代进行了讨论。此次发现,丰富了峡东中寒武世的化石资料,也为本区中寒武世地层划分对比提供了新的依据。     

Cruziana semiplicata from the Furongian (Late Cambrian) of Severnaya Zemlya Archipelago,Arctic Russia,with a review of the spatial and temporal distribution of this ichnospecies

The Furongian (Late Cambrian) Kurchavinskaya Formation of October Revolution Island, Severnaya Zemlya Archipelago, Arctic Russia , contains two distinctive morphotypes of the trace fossil Cruziana, both of which we assign to Cruziana semiplicata. A wider form shows characteristics typical of this ichnospecies with inner and outer lobes and marginal ridges. A narrow form has only an inner lobe with siculate, often interfering scratch‐marks, and rare, narrow marginal ridges. This narrow form, which shows characters in common with Cruziana tortworthi, probably represents burrowing in a strongly head‐down orientation. The record from October Revolution Island provides additional evidence that the palaeogeographical distribution of Cruziana semiplicata is not restricted to Gondwana, but also extend to parts of Baltica and North Kara. Cruziana semiplicata is known from the Furongian and Tremadocian of Gondwana, whereas on Baltica it is known only from the Furongian. Copyright © 2010 John Wiley & Sons, Ltd.     

Ichnology and Depositional Environment of the Cambrian Nagaur Sandstone (Nagaur Group) Along the Dulmera Section,Bikaner-Nagaur Basin,Rajasthan

Abstract: The Lower Cambrian Nagaur Sandstone (Marwar Supergroup) has yielded trace fossils Treptichnus, Cruziana, serially repeated Rusophycus, Diplichnites, Monomorphichnus, Bergaueria, arthropod swimming traces and leap frogging marks of Cruziana ichnofacies. This ichnofossils assemblage is dominantly preserved in fine to medium grained red sandstone beds of the Mohra Member (Nagaur Sandstone). The presence of graded rip-up clasts, current ripples, dune cross-stratification with mud drapes and tidal bundles indicates a subtidal paleoenvironment for the deposition of Nagaur Sandstone Formation, which is corroborated by the Cruziana ichnofacies trace fossil assemblage.     

Cambrian stratigraphy of eastern Yunnan

Based on investigation of several types of Cambrian sections in eastern Yunnan, we have tentatively concluded: 1) existence of the Middle Cambrian in eastern Yunnan is definitely proved; 2) the Lower Cambrian of eastern Yunnan may be divided into four formations, of which the Mei-shu-ts'un is so named for the phosphate bearing beds; 3) judging from the lithological character we recognize that the subsiding area of eastern Yunnan is still considered in the late Early Cambrian era; 4) Paragraulos and Redlichia chinensis should not be used as zoning fossils for the Tsanglangpu and Lung-wang-miao formations, respectively; 5) the Middle Cambrian of eastern Yunnan might be correlated with the Middle Cambrian of Kueichow, because Kunming was a subsiding area in the Middle Cambrian era. – Authors.     

山东长清、薛城一带中、上寒武统界线新认识

<正> 华北中寒武统与上寒武统界线问题,实际上也涉及崮山组时代的归属问题。国外学者如B.Willis和E.Blackwelder(1907),C.D.Walcott(1913),A.W.Grabau(1924),T.Kobayashi(1935)和R.Endo(1937)等认为崮山组应归中寒武世晚期。1959年由Moore主编的《三叶虫专著》(Treatise on Invertebrade Palaeontology Part O.)将崮     

Early Cambrian Ichnofossils from the Mussoorie Syncline and revision of Trace Fossil Biozonation of the Lesser Himalaya,India

A new locality bearing ichnofossils of the Cruziana Assemblage Zone-Ⅲ from the Mussoorie syncline,Lesser Himalaya,is located in rocks of Member-B of the Dhaulagiri Formation,Tal Group,exposed along the Maldewta-Chhimoli fresh road cut section.The site yielded ichnofossils Bergaueria perata,Cochlichnus anguineus,？Diplocraterion isp.,Dimorphichnus obliquus,diplichnitiform Cruziana bonariensis,Diplichnites gouldi,Glockeria isp.,Helminthopsis isp.,Monomorphichnus lineatus,Phycodes palmatum,Palaeophycus striatus,Planolites beverleyensis,Planolites montanus,Treptichnus cf.T.pedum,scratch marks and an undetermined worm impression.An Early Cambrian age （Cambrian Series 2） is assigned to the ichnofossil-bearing strata based on the stratigraphic position between the Drepanuroides and Palaeoolenus trilobite zones.A revised Cambrian ichnofossil zonation is presented for the Tal Group of the Mussoorie syncline.Together with their occurrence on rippled surfaces,and the lateral displacement of some trackways （due to current action）,a sub-aqueous shallow-marine depositional setting is proposed for the rocks of Member-B.     

昆明二村下奥陶统红石崖组顶部Cruziana rugosa遗迹化石群落的沉积环境和生态特征

Cruziana及其相关的遗迹化石是由底栖三叶虫在沉积物表面停歇、爬行所留下的遗迹,一般认为产于潮下带至浅海陆棚环境,具有古水深指示意义。然而,本文通过对昆明民富二村下奥陶统红石崖组顶部含Cruziana rugosa遗迹化石群落层位的沉积环境分析却发现,Cruziana rugosa遗迹化石群落的沉积环境为潮上带—潮间带,说明三叶虫可以在短暂暴露环境中活动。三叶虫的这种适应性活动可能为节肢动物从海洋走向陆地做好了进化准备。     

Trace fossils from the Upper Ordovician (Caradoc) of the Berwyn Hills,Central Wales

A suite of Caradocian trace fossils from the Berwyn Hills, Central Wales, are examined. They include forms produced by trilobites (Cruziana, Rusophycus, Trichophycus, Monomorphichnus), pelecypods (Lockeia), ?gastropods (?Imponoglyphus) and traces of debatable affinity probably produced by oligochaete and polychaete annelids, amphipods and crustaceans (Skolithos, Planotites, Teichichnus, Diplocraterion, Arenicolites, ?Gyrochorte, ?Palaeophycus, Vermiforichnus). Representatives of the Skolithos and Cruziana communities coexist in this assemblage and no subdivision into discrete ichnofacies is therefore possible. The trace fossils are examined in terms of their relationship to the structure and composition of Upper Ordovician communities and it is concluded that substrate and ecological controls were more important limiting environmental parameters than depth.     

Trace Fossils from Lower Cambrian Wusongger Formation in Xiaoerbulake Outcrop,Kalpin Area,Xinjiang

Based on the analysis of trace fossils collected from the typical outcrop of the Lower Cambrian Wusongger Formation in the Kalpin area, ten ichnospecies of six ichnogenus were identified in the upper member of the Wusongger Formation, with most of them being found for the first time. The trace fossils are described seriatim. The ichnospecies are mainly represented by such common trace fossils as Ophiomorpha nodosa, Helminthopsis hieroglyphica, Helminthopsis ichnosp., Planolites beverleyensis, Planolites vulgaris, Planolites montanus, Palaeophycus striatus, Palaeophycus curvatus?, Cochlichnus anguineus and Rituichnus elongatum. The trace fossils are of high diversity and low abundance, and can be diagnosed as the Cruziana ichnofacies. They can be interpreted as having formed in a shallow water environment.