Yu. D. Zakharov

The first finds of cretaceous belemnites from the Magellan Rise, Pacific Ocean

The occurrence of belemnites in Mesozoic sediments of the Pacific guyots is established for the first time (rostra Dimitobelidae gen. et sp. indet. from the late Campanian-Maastrichtian detrital limestone of the DVGI Guyot, Belemnitella? sp. from oolitic limestone of the Gelendzhik Guyot, which are presumably of the Santonian-Maastrichtian age, and Belemnitidae? gen. et sp. indet. from the Maastrichtian oolitic limestone of the Butakov Guyot, the Magellan Rise). In recent years, fossil cephalopods important in stratigraphic and paleobiogeographic aspects have been found at five guyots of that rise. New data on fossil invertebrates from the study region suggest breaks in the sedimentation here at the terminal Maastrichtian, Paleogene, and initial Neogene time. Possible limits of vertical migration in the tropical Pacific are estimated for the Late Cretaceous belemnites based on preliminary results of the oxygen isotope analysis.

EARLY INDUAN (EARLY TRIASSIC) CEPHALOPODS FROM THE DAYE FORMATION AT GUIDING, GUIZHOU PROVINCE, SOUTH CHINA

Abstract An abundant and diverse Late Griesbachian (Early Induan) Wordieoceras-dominated cephalopod fauna occurs in the lower part of the Daye Formation at the Wenjiangsi section, Guiding County, Guizhou Province, South China. The cephalopod fauna consists of 17 species belonging to 10 genera, including two nautiloid species and 15 ammonoid species representing the families Ophiceratidae, Proptychitidae, Meekoceratidae, and Khangsariidae. One genus and five species are new: Vishnuites wenjiangsiensis, Pseudovishnuites guidingensis, Wordieoceras guizhouensis, Gyrophiceras subplicatum, and Hubeitoceras? Wangi.

New geological and paleontological data on Alba Guyot (Magellan Seamounts, Pacific Ocean)

New materials obtained in the Pacific during cruises of the R/V Gelendzhik carried out by the State Scientific Center Yuzhmorgeologiya in 2000–2001 make it possible to specify the geologic and geomorphologic structure of Alba Guyot and clarify lithological and paleontological characteristics of lithotectonic rock complexes ranging from the Early Cretaceous to Pleistocene in age. Based on macro-and microfossils from sedimentary rocks several “transgressive” phases are distinguished in the guyot development: Cenomanian-Turonian, late Campanian-Maastrichtian, late Paleocene-middle Eocene, and Late Cenozoic. Finds of Paleogene molluscan and coral remains, together with planktonic foraminifers, imply relatively shallow sedimentation settings on Alba Guyot during the early Paleocene.

The first detailed δ 13 С оrg record in Permo-Triassic boundary deposits in the Kolyma–Omolon region (Northeast Asia)

We have obtained the first detailed δ13Сorg record in Permian-Triassic boundary sediments in deepwater facies in Northeast Asia (Kolyma–Omolon region, Balygychan Basin). Our data show good convergence both with the Setorym River section (South Verkoyansk region), where the Permian-Triassic boundary has been determined approximately, and with a number of other sections of Permian-Triassic boundary sediments in the Boreal and Tethyan Superrealms, in particular, in the Buchanan Lake section in Arctic Canada, the Festningen section on Spitsbergen, the Wadi Shahha section on the Arabian Peninsula, and published sections in the Dolomites.

Lower triassic zonation of southern Primorye. Article 2. First conodont findings in Churkites cf. syaskoi beds at the western coast of the Ussuri gulf

Contrary to the popular opinion that the lower Olenekian Scythogondolella milleri Zone corresponds to the almost entire Anasibirites ammonite zone or its analogs (for example, the Anawasatchites tardus Zone), we have arrived at the conclusion that the Milleri Zone in the southern Primorye region should likely be correlated only with the lower part of Anasibirites-bearing strata: lower member A of the Anasibirites nevolini Zone in the SMID quarry section and the lower part of the Churkites cf. syaskoi Beds overlying the Euflemingites prynadai Beds in the Tri Kamnya Cape section. The conodont assemblages from different facies of the Anasibirites nevolini Zone in southern Primorye differ from each other in taxonomic composition and diversity at the generic level, as well as in sizes of specimens.

Importance of carbon isotopic data of the Permian-Triassic boundary layers in the Verkhoyansk region for the global correlation of the basal Triassic layer

This paper is dedicated to a global correlation of marine Permian-Triassic boundary layers on the basis of partially published and original data on the δ13Corg and δ13Ccarb values of the Suol section (Setorym River, South Verkhoyansk region). The section consists of six carbon isotopic intervals, which are easily distinguishable in the carbon isotopic curves for a series of Permian-Triassic reference sections of Eurasia and Northern America, including paleontologically described sections of Central Iran, Kashmir, and Southern China. This suggests that the Permian-Triassic boundary in the Suol section is close to the carbon isotopic minimum of interval IV. In light of new data, we suggest considering the upper part of the Late Permian Changhsingian Stage and the lower substage of the Early Triassic Induan Stage of Siberia in the volumes of the rank Otoceras concavum zone and the Tompophiceras pascoei and Wordieoceras decipiens zones, respectively. The O. concavum zone of the Verkhoyansk region probably corresponds to the Late Changhsingian Hypophiceras triviale zone of Greenland. The carbon isotopic intervals II, III, IV, and V in the Permian-Triassic boundary layers of the Verkhoyansk region traced in a series of the reference sections of Eurasia correspond, most likely, to intensification of volcanic activity at the end of the Late Changhsingian and to the first massive eruptions of Siberian traps at the end of the Changhsingian and the beginning of the Induan Stages. New data indicate the possible survival of ammonoids of the Otoceratoidea superfamily at the species level after mass extinction of organisms at the end of the Permian.

New members of the family flemingitidae (Ammonoidea) from the Lower Triassic of South Primorye

New species of flemingitid ammonoids (Flemingites trikamnyaensis sp. nov., F. alexanderi sp. nov., Rohillites? ambiguus sp. nov., Euflemingites extremus sp. nov.) from the Olenekian of South Primorye are described. The shell interior of flemingitid ammonoids is studied for the first time based on Ussuriflemingites abrekensis Shigeta et Zakharov. The usefulness of the early-ontogenetic morphological test (EMT) for substantiation of ammonoid taxa at the family level is discussed.

New representatives of the family Melagathiceratidae (Ammonoidea) from the Lower Triassic of South Primorye

A new ammonoid genus, Ussurijuvenites (Melagathiceratidae), is described from the early Olenekian of South Primorye, represented by two new species (U. popovi sp. nov. and U. artyomensis sp. nov.); data on the inner shell structure of melagathiceratid ammonoids (based on U. artyomensis sp. nov.) are presented for the first time.

Roadoceras (Permian Ammonoidea) from the Qubuerga Formation in the Mt. Everest Area in Southern Tibet

Abstract The Quberga Formation of the Selong Group in the Mt. Everest area in southern Tibet was previously assigned to Artinskian or Kungurian in age mainly based on an occurrence of an ammonoid species Uraloceras xizangense. However, a restudy on the previously and subsequently collected specimens of Uraloceras xizangense suggests that this species is re-assignable to Roadoceras xizangense, and therefore probably indicates an age between late Capitanian and early Wuchiapingian for the lower part of the Qubuerga Formation. Temporally, Roadoceras ranges from late Wordian to Wuchiapingian and was palaeobiogeographically distributed in the Palaeoequatorial and bi-temperate regions.

New middle Olenekian (early Triassic) ammonoids of South Primorye

Nine new ammonoid species (Inyoceras singularis, Yvesgalleticeras proximus, Tirolites opiparus, Koninckitoides solus, Bajarunia magna, Albanites vulgaris, Nordophiceratoides praecox, Palaeophyllites admirandus, Kamenushkaites acutus) and one new genus of the family Palaeophyllitidae (Kamenushkaites) are described based on material from the mid-Olenekian of the Kamenushka River basin, South Primorye.