Upper Cretaceous

Demonstration of Gemmation among Cretaceous Skeletal Sponges – Hexactinellida

Authors: Pervushov E. M.

The examination of the modular organization in fossil skeletal sponges (Hexactinellida) is mainly related to a study of their vegetative reproduction. The concepts of the reproductive forms for both Recent and Mesozoic hexactinellids can be ambiguous. Examples of the skeletons of fossil sponges from the Late Cretaceous of the Volga River basin, with morphologically detached and naturally distributed sprouts interpreted as buds, are shown. 

First Magnetostratigraphic Data on the Maastrihtian of Mountain Crimea (Bakhchysarai Region)

Authors: Gujikova A. A.

The representative data about magnetic susceptibility, its anisotropy before and after heating up to 500°C and other petromagnetic characteristics were received on two sections of carbonate sediments of Maastrihtian – Chahmahly and Takma, located in Bakhchysarai region of the Republic of Crimea. In the studied sections there were established the magnetozones of normal and anomalous polarity, the comparison of determined zones with Geomagnetic Polarity Time Scale was conducted.

Integrated Bio and Magnetostratigraphic Study of the ≪Ozerki≫ Sections (Upper Cretaceous, Right Bank of the Volga in the Saratov Region). Paper 2. Oryctocoenosis Characteristics and Biostratigraphy

Authors: Pervushov E. M., Seltzer V. B., Kalyakin E. A., Fomin V. A., Ryabov I. P., Ilinskiy E. I., Gujikova A. A., Biryukov A. В., Surinskiy A. M.

In the ≪Ozerki≫ sections, in the terrigenous and carbonate rocks, a faunal complex has been determined – unusually diversified and relatively abundant for the right-bank part of the Saratov Region. Examination of the specified groups of fossil invertebrates has allowed to propose variants for biostratigraphic division and correlation of the sections under consideration. The carbonate rocks are supposed to belong to the Turonian-Coniacian and the underlying terrigenouscarbonate rocks are regarded as the Lower Turonian ones.

Integrated bio and Magnetostratigraphic Study of the ≪Ozerki Sections≫ (Upper Cretaceous, Right Bank of the Volga in the Saratov Region). Paper 1. Section Characteristics, Results of Petromagnetic and Magnetic-mineralogical Examinations

Authors: Pervushov E. M., Seltzer V. B., Kalyakin E. A., Fomin V. A., Ryabov I. P., Ilinskiy E. I., Gujikova A. A., Biryukov A. В., Surinskiy A. M.

In the right-bank part of the Saratov Region, a section of terrigenous and carbonate rocks has been determined to underlie the ≪sponge≫ horizon conventionally dated back to the Santonian. The maximum thickness of the marls, constituting a substantial portion of the section, occurs in the western part of the region. Field description is presented alongside with the correlation scheme of the recognized stratified intervals in the three joined Ozerki objects and the results of petromagnetic and magnetic-mineralogical examinations in the carbonate rock interval.

Petromagnetic Indicators of Layers with High Concentration of Cosmogenic Substance in Maastrichtian of Volga Region and Cis-Caspian Region

Authors: Gujikova A. A., Tselmovich V. A., Atkin V. S.

The level with anomalous high values of natural remanent magnetization and Koenigsberger ratios was identify in the Upper Maastrichtian of Vol’sk depression (Saratov Volga Region). The microprobe studies of samples from this layer registered elevated concentrations of microparticles of iron, nickel, intermetallics and magnetite spherules of cosmic genesis. Similar petromagnetic anomaly was detect in the uppermost of Maastrichtian in the South Cis-Caspian (Aktolagay Plateau, Kazakhstan).

The Santonian – Campanian Rock Boundary Interval within the Zhirnovsk Uplift (Volgograd Region)

Authors: Pervushov E. M., Seltzer V. B., Kalyakin E. A., Gujikova A. A.

A lithologically continuous Santonian and Campanian rock section has been examined; the character of rock interrelations has been determined as the one common to the junction area of the northern part of the Don-Medveditsa and the southern termination of the Rtishchevo‑Balanda swells and the Karamysh depression.

The History of the Study Sea Urchins from the Upper Cretaceous of the Volga Region

Authors: Kalyakin E. A.

In the course of this work we cast the light on the state of research of the Late Cretaceous sea urchins in the Volga region as well as the development of ideas about their distribution in the rocks of the Upper Cretaceous in the region. Resources used in the research include studies about this group of invertebrates since the beginning of the XIX century up to the present day. It was estab­lished that the vast majority of publications consist of fragmentary information containing mentions of echinoderm remnants findings.

Neogenesis in Structure of Skeletons of Late Cretaceous Sponges Contributed to the Formation of Polyosculumic Forms

Authors: Pervushov E. M.

Arterial directions in formation of module organization of skeleton hexactinellids are caused by vegetative forms of reproduction. It is supposed that some tendency of selection of protozoa module forms can be traced in morphogenesis of separate generic types of late Cretaceous sponges. The concept “polyosculumic„ sponges is considered in vast context personally in reference to skeletons with some osculumics formed in the result of partial regeneration of organism

Pages