scholarly journals The lower boundary of the Haljala Regional Stage (Sandbian, Upper Ordovician) in Estonia

2020 ◽  
Vol 69 (2) ◽  
pp. 76 ◽  
Author(s):  
T Paiste ◽  
P Männik ◽  
J Nõlvak ◽  
T Meidla
Keyword(s):  
Lower Boundary ◽  
Upper Ordovician ◽  
Regional Stage

Middle–Upper Cambrian Trilobites of the Genus Nganasanella Rosova, 1963 and Their Stratigraphic Significance

2021 ◽  
Vol 62 (07) ◽  
pp. 746-764
Author(s):  
A.L. Makarova
Keyword(s):  
Siberian Platform ◽  
Type Species ◽  
Lower Boundary ◽  
River Section ◽  
Shallow Marine ◽  
Upper Cambrian ◽  
Regional Stage ◽  
Stratigraphic Position ◽  
Marine Facies ◽  
Stratigraphic Chart

Abstract —This paper presents a revision for the genus Nganasanella Rosova, 1963, first described in the stratotype of the Kulyumbean Regional Stage of the Kulyumbe River section (northwest of the Siberian Platform). This section is typical of the upper Cambrian sediments of the Kotuy–Igarka facies region, formed in a shallow marine shelf. As shown by the study, the genus comprises seven species. The species N. nganasanensis Rosova, 1963 (type species), N. tavgaensis Rosova, 1963, N. glabella (Kobayashi), 1943, N. granulosa Rosova et Makarova, 2009, and N. vernacula Rosova et Makarova, 2009 are found in the Siberian Platform. The species N. australica sp. nov. occurs in northeastern Australia. The species N. trisulcatus (Ergaliev), 1980 is widespread in southern Kazakhstan. Some species (N. granulosa and N. vernacula) are found in open marine facies sediments along with the cosmopolitan agnostid species Glyptagnostus reticulatus (Angelin), 1851, serving as a marker of the lower boundary of upper Cambrian strata in the International Chronostratigraphic Chart and the General Stratigraphic Chart of Russia. The species N. trisulcatus and N. australica are found slightly above Glyptagnostus reticulatus. Representatives of the genus Nganasanella are a link between strata of different facies containing different trilobite associations. Their stratigraphic position can serve as an argument for the correlation of the Kulyumbean Regional Stage with units containing Glyptagnostus reticulatus, i.e., the Omnian and Idamean regional stages, the lower parts of the Kutugunian Horizon and the Sakian Regional Stage, and the Paibian Stage of the International Chronostratigraphic Chart.

scholarly journals STRATOTIPE DOLBORIAN FORMATION OF THE UPPER ORDOVICIAN OF THE SIBERIAN PLATFORM

2021 ◽  
Vol 2 (1) ◽  
pp. 254-262
Author(s):  
Alexander V. Timokhin
Keyword(s):  
Siberian Platform ◽  
Lower Boundary ◽  
Upper Ordovician ◽  
History Of

The analysis and correlation of typical sections of the Dolbor formation and the history of its allocation are carried out. A new stratotype of this formation is proposed (in the Gaindinskaya-3 well and two sections on the Lower Chunku River), in which the lower boundary of the formation does not correspond to the lower boundary of the Dolborian horizon.

The Leonian Stage (early Middle Cambrian): a unit for Cambrian correlation in the Mediterranean subprovince

1999 ◽  
Vol 136 (1) ◽  
pp. 39-48 ◽  
Author(s):  
K. SDZUY ◽  
E. LIÑÁN ◽  
R. GOZALO
Keyword(s):  
Lower Boundary ◽  
Point Of View ◽  
The Other ◽  
Middle Cambrian ◽  
Regional Stage ◽  
The Mediterranean ◽  
Upper Boundary

The Leonian (early Middle Cambrian) regional Stage of Iberia is revised from a lithostratigraphic and biostratigraphic point of view in order to propose it as a chronostratigraphic unit for the Mediterranean subprovince (outcrops in Spain, France, Italy, Germany, Morocco and Turkey). This revision now permits a correlation of the Leonian Stage with the other early Middle Cambrian regional Stages. For this correlation the first appearance datum (FAD) of Eoparadoxides mureroensis, Macannaia spp., Schistocephalus antiquus and Oryctocara granulata are employed for the lower boundary; while the FADs of Badulesia tenera, Ctenocephalus (Hartella) spp., Parasolenopleura aculeata and Triplagnostus gibbus are employed for the upper boundary.

scholarly journals POSITION OF THE PALEOGENE STAGES BOUNDARIES IN THE SEDIMENTARY SECTION OF PLATFORM UKRAINE: CURRENT STATE, DETERMINATION CRITERIA

2021 ◽  
Vol 14 (1) ◽  
pp. 72-99
Author(s):  
Tamara S. Ryabokon
Keyword(s):  
Western Europe ◽  
Sedimentary Cover ◽  
Lower Boundary ◽  
Regional Stage ◽  
Current State ◽  
Global Correlation ◽  
State Determination ◽  
North Western ◽  
Stratigraphic Chart ◽  
Stage Boundaries

Data on the Global Stratotypes Sections and Points of the Paleogene Stages of the modern International Stratigraphic Scale, as well as the criteria for determining the boundaries of the Paleogene Stages in North-Western Europe are presented. The characteristics of the position of the stage boundaries in the sedimentary section of the platform Ukraine are given. In the Paleogene section of Southern Ukraine, the lower boundaries of the Ypresian and Priabonian were recognized by global correlation markers. According to the modern International Stratigraphic Scale, the position of the Lutetian / Bartonian and Rupelian / Chattian boundaries in the sedimentary sections of Southern and Northern Ukraine has been clarified in comparison with previous views. The position of most stage boundaries in the biostratigraphic (zonal) scheme of the Paleogene of Ukraine is more accurately determined. The criteria for identification for some of them in the section of the south and north of Ukraine are proposed. Most of the stage boundaries are represented by hiatus in the sedimentary cover of the platform Ukraine. Part of the boundaries of the Paleogene stages coincides with the boundaries of the regional stratigraphic units of Southern and Northern Ukraine, namely: – the Cretaceous / Paleogene boundary is at the base of the Belokamenskia and Pselian regional stages; – the Paleocene/Eocene boundary coincides with the boundary of the Merlian/Kanevian regional stages; – the Ypresian/Lutetian boundary coincides with the Kanevian/Buchakian regional stages; – the lower boundary of Priabonian is at the base of the Almian and Obukhovian regional stages; – the Eocene/Oligocene boundary passes on the limit of Almian/Planorbellian and Obukhovian/Mezhygorian regional stages; – the Rupelian/Chattian boundary is at the limit of the lower and upper regional substages of Kerleutian regional stage and at the limit of the lower and upper regional substages of the Berekian regional stage. The following stage boundaries are not coinciding with regional stage boundaries: – the Danian/Selandian boundary is within upper part of the Belokamenskian and Pselian regional stages; – the Selandian/Thanetian boundary is trassing in the lower part of the Kachian and Merlian regional stages; – the lower boundary of Ypresian is in the uppermost part of the Kachian regional stage; – the Ypresian/Lutetian boundary is within the Simferopolian regional stage; – the Lutetian/Bartonian boundary is in the lowest part of the Kumian regional stage and within the Kievian regional stage. Key words: International Stratigraphic Chart, Paleogene, stage, boundary, regional stage, Ukraine

Morphometric characteristics of competent proximal valves of the great saphenous vein and superficial femoral vein in vivo according to ultrasound angioscanning data

2019 ◽  
Vol 18 (3) ◽  
pp. 16-22
Author(s):  
E. K. Gavrilov ◽  
H. L. Bolotokov ◽  
E. A. Babinets
Keyword(s):  
Saphenous Vein ◽  
Great Saphenous Vein ◽  
Femoral Vein ◽  
Lower Boundary ◽  
Average Diameter ◽  
Lower Limbs ◽  
Functional Test ◽  
Natural Form ◽  
Superficial Femoral Vein ◽  
Venous Diameter

Introduction. It seems relevant to study the ultrasound anatomy and physiology of the proximal valve segments of the superficial femoral vein (SFV) and the great saphenous vein (GSV) to develop effective reconstructive surgical interventions on venous valves in chronic vein diseases.The aim of the survey was to study the ultrasound anatomy of the venous wall, the size and shape of the proximal SFV and GSV valves are normal at rest and during the functional test Valsalva.Material and methods. Proximal valve SFV studies were performed in 144 lower limbs in 115 people (mean age 51.1 ± 14.4 years, 60 women and 55 men), proximal GSV valves studies - in 82 lower limbs in 67 persons (average age 45, 1 ± 13.3 years, 33 women, 34 men). A longitudinal and transverse ultrasound scanning of the femoral vein bifurcation and safenofemoral junction areas were performed, the structures of the proximal SFV and GSV valves were visualized, the valve shape was measured and the diameter of the veins was measured at the level valves at the base of the valves (inlet diameter), at the point of maximum ectasia (diameter of ectasia), at the upper border of the valve (diameter of the outlet), as well as measuring the length of the valve a (length to ectasia, the total length of the valve). The degree of ectasia over the valve was judged by calculating the relative venous diameter change (RVDC).Results. the average diameter of the SFV at the level of the lower boundary of its first valve was 10.01 ± 1.44 mm. The average diameter of the SFV at the level of the maximum ectasia of its first valve was 13,1±2 mm. The average value of the index of RVDC for SFV was 31%±10,4%. An increase in the diameter of the vein in the zone of supravalvular ectasia up to 20% corresponded to the spindle-shaped valve, more than 20% - to the clavate form, which was noted in the majority of the examined. The change in the relative venous diameter of the SFV on the Valsalva test was 38,2%±12,4%. The average diameter of the GSV at the base of the first valves was 6,07±1,25 mm. The average diameter of the GSV at the level of the maximum ectasia of the osteal valve was 9,44±1,69 mm. The average RVDC for GSV was 58%±24%.Conclusion. the natural form of proximal SFV and GSV valves is clavate with presence of the significant supravalvular ectasia, which was noted in the majority of the subjects alone and in all during the performance of the Valsalva functional test.

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