scholarly journals Ordovician stratigraphy of the Kovel-1 well (Volkhov–Haljala) in the Volynia region, northwestern Ukraine

2004 ◽  
Vol 51 ◽  
pp. 47-69
Author(s):  
Tõnis Saadre ◽  
Rein Einasto ◽  
Svend Stouge
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Carbonate Rocks ◽  
Carbonate Sediments ◽  
Middle Ordovician ◽  
Tectonic Events ◽  
Depositional Cycles ◽  
Open Shelf

The Ordovician succession of the Kovel-1 well in the Volynia region, northwestern Ukraine is composed of a basal 0.6 m thick siliciclastic unit succeeded by 24.7 m Lower and lower Middle Ordovician carbonate sediments. The carbonate rocks are divided into 13 informal lithologic units. The carbonate sediments accumulated in marine shallow water open shelf and shoal or turbulent environs. Biostratigraphically, the succession is referred to seven chitinozoan zones and 12 conodont biozones. Integration, chronostratigraphic position and correlation of the proposed biozones with those from Baltoscandia are briefly discussed. Four major unconformities are recognized within the succession: 1) the Pakerort(?)–Volkhov unconformity, 2) the mid Volkhov unconformity, 3) the early Kunda unconformity and 4) the early Mid Ordovician hiatus. The latter straddles the Oeland–Viru regional Series boundary in the well. The early Mid Ordovician unconformity is prominent and the corresponding hiatus spans the Aseri and Lasnamägi regional stages (= upper Darriwilian). A complex of cyclic transgressive–regressive depositional pattern prevailed and the whole succession is referred to three major depositional cycles. The major depositional cycles are related to global eustatic sea-level cycles in general and hypothetic way to tectonic events caused by collisions of Peri-Gondwanan microcontinents with Baltica.

Evidence for a widespread carbon isotopic event associated with late Middle Ordovician sedimentological and faunal changes in Estonia

1999 ◽  
Vol 136 (1) ◽  
pp. 49-62 ◽  
Author(s):  
LEHO AINSAAR ◽  
TÕNU MEIDLA ◽  
TÕNU MARTMA
Keyword(s):  
Isotopic Composition ◽  
Sea Level ◽  
Thermohaline Circulation ◽  
Carbon Isotopic Composition ◽  
Shelf Area ◽  
Carbonate Sediments ◽  
Sea Level Changes ◽  
Middle Ordovician ◽  
Carbon Isotopic ◽  
The North

An episode of remarkable biotic, climatic, sea-level and facies changes took place during the late Viruan (Caradoc) epoch in the Baltoscandian area. We studied the carbon isotopic composition of carbonate sediments from this period. Data on the stable carbon isotopic composition of whole-rock carbonates from three south Estonian core sections, together with those on ostracode, distribution are presented. In two core sections, a positive δ13C shift of 2 ‰ was revealed in the upper part of the Keila Stage (mid-Caradoc). The comparison of isotope and ostracode data in the sections suggested the occurrence of a gap of late Keilan age in the marginal area of the basin equivalent to the North Estonian Confacies Belt. The beginning of the excursion approximately coincided with climatic and sea-level changes in the shallow shelf area. The peak of the late Keilan excursion preceded the biotic crises and maximum black shale accumulation in the Baltoscandian palaeobasin. An approximately synchronous carbon isotopic event has been reported from North America, referring to a possible global oceanographic event in the Caradoc epoch. Although the positive carbon isotopic excursion and related environmental events of the late Keilan age have some unique features, they show more similarities to the end-Ordovician and Silurian events, characterized by oceanic change from stratified state to thermohaline circulation state, than to warm anoxic events related to eustatic sea-level rise.

Ecostratigraphical interpretation of lower Middle Ordovician East Baltic sections based on brachiopods

2009 ◽  
Vol 146 (5) ◽  
pp. 717-731 ◽  
Author(s):  
CHRISTIAN M. Ø. RASMUSSEN ◽  
ARNE T. NIELSEN ◽  
DAVID A. T. HARPER
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Fourth Order ◽  
Water Depth ◽  
Soft Substrate ◽  
Middle Ordovician ◽  
Systematic Assessment ◽  
Level Curves ◽  
Ice Caps ◽  
Baltic Area

AbstractA detailed ecostratigraphical framework is established for the lower Middle Ordovician Kundan regional stage of the East Baltic area corresponding to the Asaphus expansus, A. raniceps and A. eichwaldi trilobite zones (lower Darriwilian). The study is based on approximately 6200 brachiopods collected bed by bed from limestone sections in northern Estonia (Harku Trench and Saka) and western Russia (Putilovo Quarry, Lava River canyon and Lynna River valley) with, in addition, the first detailed systematic assessment of the Kundan brachiopods of the East Baltic. These sections represent an oblique depth transect some 400 kilometres long, deepening eastwards. Five biofacies associations have been recognized using detrended correspondence and cluster analyses: a shallow-water Lycophoria association, a transitional Gonambonites association and two deeper-water associations, the soft-substrate Orthis callactis and the hard-substrate Orthambonites associations. A separate, fifth soft-substrate association is present in the marl beds at the main locality of Putilovo Quarry. The associations reflect a combination of palaeo-water depth and substrate. The biofacies facilitate an ecostratigraphical correlation along the transect, and third and fourth order sea-level curves are reconstructed, reflecting mainly eustasy. The sea-level was relatively low, early in the Kundan, but then rose significantly into the A. raniceps Biozone. This corroborates the recent discovery of possible small early Darriwilian ice caps on Gondwana.

scholarly journals Ordovician conodont biofacies of the upper La Silla and San Juan formations (middle Tremadocian-lower Dapingian) at Cerro La Silla, Argentine Precordillera

2021 ◽  
Author(s):  
Matías J. MANGO ◽  
undefined Guillermo L. ALBANESI
Keyword(s):  
Cluster Analysis ◽  
Sea Level ◽  
Carbonate Rocks ◽  
Carbonate Ramp ◽  
San Juan ◽  
Total Abundance ◽  
Sea Level Changes ◽  
Middle Ordovician ◽  
Conodont Biofacies ◽  
Argentine Precordillera

Conodonts from the upper La Silla (9.6 m thick) and San Juan formations (264.7 m thick) at the Cerro La Silla section are analyzed for the identification of faunal dynamics, biofacies and sea-level changes. The conodont collection of 11 388 specimens was recovered after digestion of 41 samples of carbonate rocks, totalizing 88.155 kg. Conodont total abundance and generic diversity graphs, as well as cluster analysis, reveal seven biofacies. The Colaptoconus, Tropodus-Reutterodus, Oepikodus-Prioniodus, Juanognathus-Bergstroemognathus, Juanognathus-Oepikodus-Protopanderodus, Juanognathus-Protopanderodus, Juanognathus-Semiacontiodus biofacies are determined. These biofacies represent middle to outer carbonate ramp environments for the San Juan Formation. The associated analysis of biofacies and lithology allow for the recognition of two transgressive events in the San Juan Formation at the Cerro La Silla section, which could be related to transgressive systems tracts (TST) that occurred during the Early and Middle Ordovician (middle Tremadocian-early Dapingian).

Sedimentology, faunal content and pollen record of Middle Pleistocene palustrine and lagoonal sediments from the Peri-Adriatic basin, Abruzzi, eastern central Italy

2016 ◽  
Vol 86 (3) ◽  
pp. 359-372 ◽  
Author(s):  
Pierluigi Pieruccini ◽  
Claudio Di Celma ◽  
Federico Di Rita ◽  
Donatella Magri ◽  
Giorgio Carnevale ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Central Italy ◽  
Freshwater Wetlands ◽  
Middle Pleistocene ◽  
Pollen Record ◽  
Vegetation Development ◽  
Oxygen Isotope Stage ◽  
Open Forest ◽  
Facies Succession

AbstractA 25 m-thick outcrop section exposed at Torre Mucchia, on the sea-cliff north of Ortona, eastern central Italy, comprises a rare Middle Pleistocene succession of shallow-water and paralic sediments along the western Adriatic Sea. An integrated study of the section, including facies and microfacies analyses, and characterization of paleobiological associations (mollusks, fishes, ostracods, foraminifers and pollen), enable a detailed reconstruction of the paleoenvironmental and paleoclimatic conditions during deposition. The shallow-water deposits include a transgressive, deepening- and fining-upward shoreface to offshore-transition facies succession overlain by a regressive shoreface-foreshore sandstone body with an erosive base and a rooted and pedogenically altered horizon at the top that imply deposition during sea-level fall. This forced regressive unit is overlain by paralic strata forming a transgressive succession comprising palustrine carbonates and back-barrier lagoonal mudstones. The palustrine carbonates exhibit some of the typical features encountered in palustrine limestones deposited within seasonal freshwater wetlands (marl prairies). Following the sea-level rising trend, the freshwater marshes were abruptly replaced by a barrier-lagoon system that allowed deposition of the overlying mud-rich unit. Within these deposits, the faunal assemblages are consistent with a low-energy brackish environment characterized by a relatively high degree of confinement. The pollen record documents the development of open forest vegetation dominated by Pinus and accompanied by a number of mesophilous and thermophilous tree taxa, whose composition supports a tentative correlation with Marine Oxygen Isotope Stage 17. The new pollen record from Torre Mucchia improves our understanding of the vegetation development in the Italian Peninsula during the Middle Pleistocene and sheds new light on the role played by the most marked glacial periods in determining the history of tree taxa.

Novel Integrated Approach for Complex Carbonate Reservoirs Testing with Wireline Formation Tester: Yurubcheno-Tokhomskoye Field Cases Study

2021 ◽  
Author(s):  
Yakov Dzhalatyan ◽  
Mikhail Charupa ◽  
Aydar Galiev ◽  
Yevgeniy Karpekin ◽  
Sergey Egorov ◽  
...  
Keyword(s):  
Carbonate Rocks ◽  
Fractured Reservoirs ◽  
Integrated Approach ◽  
Carbonate Sediments ◽  
Drilling Mud ◽  
Acoustic Reflection ◽  
Resistivity Logging ◽  
First Time ◽  
Fluid Inflow ◽  
Low Porosity

Abstract In the presented paper, the object of the study are carbonate rocks of the Riphean and clastic-carbonate rocks of Vendian-Cambrian ages, uncovered by the well drilled at Yurubcheno-Tokhomskoye field. These reservoirs are characterized by extremely low porosity (1-4%) and determining saturation nature and fluid contacts cannot be reliably solved by conventional wireline petrophysical logging. Solutions to these problems are provided by interval testing using wireline formation evaluation testing tool (WFT). However, to obtain quality results from WFT testing it is important to identify porous intervals first by using advanced wireline logging services which are sensitive to porosity and fractures. In order to select the optimal WFT toolstring combination and to prospective testing intervals, advanced petrophysical wireline logging suit ran first. Porous reservoirs were identified from density, neutron and nuclear magnetic resonance evaluation. Saturation evaluated through dielectric and induction-based resistivity logging. In fracture-vug type reservoir, the main inflow of formation fluid into the well is provided from fractures, so it was very important to allocate conductive fractures to plan test intervals for WFT accordingly. based on imagers evaluation, fractures and faults were visualized; using Stoneley's wave conductive fractures, not clogged with drilling mud solids were identified; borehole acoustic reflection survey was used to segregate large fractures that propagated in the reservoir; During WFT logging, a total of 23 intervals were tested, for 8 of which reservoir fluid inflow was achieved, in all others, mainly with low porosity or single non-conductive fracture, the inflow was not achieved or was insignificant. According to the results of WFT testing, the nature of saturation for clastic-carbonate sediments of Vendian age was determined. Inflow of formation fluid (oil and water) from Riphean fractured reservoirs was achieved from 6 intervals, with identified fractures according to described above advanced logging suit. In addition, pressure transient analysis was performed, to measure the formation pressure, define pressure gradient curves and assess the fluids contact level with high confidence, for the first time for this field.

The pattern of the tectonic joints and the development of the Vlychada karst show cave in Diros, Peloponnesus, Greece

2021 ◽  
Author(s):  
Christos Filis ◽  
Emmanuel Skourtsos ◽  
Nikolaos Karalemas ◽  
Vasilios Giannopoulos ◽  
Ioannis Giannopoulos ◽  
...  
Keyword(s):  
Characteristic Feature ◽  
Sea Level ◽  
Carbonate Rocks ◽  
Meteoric Water ◽  
Weather Conditions ◽  
High Angle ◽  
Tectonic Structures ◽  
Joint System ◽  
Factors Influencing ◽  
Show Cave

<p>The most characteristic feature of carbonate rocks is that they are prone to dissolution due to the meteoric water circulation which is enriched in CO<sub>2</sub>. One of the factors influencing this phenomenon is the existence of discontinuities within the mass of carbonate rocks. The Diros Vlychada show cave, on the peninsula of Mani in Peloponnese, Greece, has developed in marbles that belong to the Plattenkalk geotectonic unit. Most of the cave is flooded with water and its level changes depending on the external weather conditions and variations in sea level. The deformation of the marbles is represented by tectonic structures formed during the Lower Miocene metamorphism and their subsequent exhumation. The final uplift stage took place during the Pliocene-Quaternary and is still active. Five joints systems were distinguished:</p><p>A NW-SE joint system which is subdivided into a subsystem with low-angle dips, mainly towards to the NW, related to the main foliation of the marbles and a second subsystem characterized by stretching joints of the same strike (elongated joints), which have high-angle dips, also towards the NW. The latter system intersects the former but is confined between marble bedding and does not extend to more than three beds (the bedding is defined by the first subsystem).</p><p>A NW-SE striking joint system characterized by stretching joints with high-angle dips, which intersects diagonally the two previous. This system extends between more than three marble beds.</p><p>Two systems show E-W and N-S strike with the first one much better expressed. Those joints have developed diagonally to the previous ones. These are mainly shear joints that intersect the first system and are propagated within many marble beds.</p><p>The chambers of the cave have been developed along NW-SE and E-W directions. The first one is identified with the joint system that has been developed transversely to the strike of the marble foliation and the second in parallel with the main system of the shear joints. It is interesting that the bays forming the coastline of the Mani peninsula, have developed in an E-W direction, which coincides with both one of the growth directions of the cave and one of the joints systems, which correspond to shear joints developed during the folding of the marbles. Stalactites and stalagmites grow in a NE-SW direction that is identical to the elongated joints which form the system that is parallel to the foliation strike. Groundwater flow along these branches may be slower as these branches appear to be restricted between marble bedding.</p>

Characteristics and its Environment Implications of Carbon and Oxygen Isotopic of Ordovician Carbonate Rock in Yubei Area

2015 ◽  
Vol 1092-1093 ◽  
pp. 1375-1378
Author(s):  
Qian Zhang ◽  
Wen Hui Huang ◽  
Ya Mei Zhang
Keyword(s):  
Sea Level ◽  
Carbonate Rocks ◽  
Carbonate Rock ◽  
Burial Depth ◽  
Oxygen Stable Isotopes ◽  
Oxygen Isotopic ◽  
Oxygen Stable Isotope ◽  
The Stability ◽  
Diagenetic Environment ◽  
Stable Isotope Data

Based on a large number of carbon and oxygen stable isotope data, researched environment characteristics of Ordovician carbonate rocks in Yubei area, Tarim Basin. According to carbon, oxygen stable isotopes (&13C, &18O) data, combining the diagenetic environment characteristics studied all kinds of geochemical characteristics of rocks in Yubei area. The research results show that: Paleosalinity feature of Ordovician carbonate rocks in this area reflected the carbonate rocks is formed in the stability of the marine environment and basically kept the composition of carbon and oxygen isotopic of the original environment. the paleo temperature characteristics indicate that the diagenetic burial depth was increased first and then decreased, the sea level characteristics indicate that the sedimentary strata by Yingshan period to Lianglitage period corresponds with a rise in sea level.

scholarly journals Upper Arenig trilobite biostratigraphy and sea-level changes at Lynna River near Volkhov, Russia

2003 ◽  
Vol 50 ◽  
pp. 105-114
Author(s):  
T. Hansen ◽  
A.T. Nielsen
Keyword(s):  
Shallow Water ◽  
Sea Level Rise ◽  
Sea Level ◽  
Abundance Ratio ◽  
Basal Part ◽  
Sea Level Changes ◽  
Faunal Turnover ◽  
Lower Ordovician ◽  
Water Conditions ◽  
Tentative Interpretation

Over 5000 trilobites have been collected from Lower Ordovician rocks exposed at the Lynna River in the Volkhov region, east of St. Petersburg, Russia. Bed-by-bed sampling has been carried out through the upper part of Volkhov Formation (top of Jeltiaki Member and the entire Frizy Member), the Lynna Formation and the basal part of the Obukhovo Formation. This interval, which is 7.5 metres thick, correlates with the upper part of the Arenig Series, and presumably even ranges into the very base of the Llanvirn. A preliminary biostratigraphical investigation of top Jeltiaki Member (BIIβ), Frizy Member (BIIγ) and basal Lynna Formation (BIIIα) reveals a rather continuous faunal turnover lacking sharp boundaries, and the biostratigraphical zonation (BIIβ–BIIIα) is primarily defined by the index trilobite taxa. The trilobite ranges are generally in agreement with the pattern described by Schmidt in 1907. The abundance ratio between Asaphus and the ptychopygids seems to be related to changes in relative sea level with Asaphus preferring the most shallow water conditions. A tentative interpretation of sea-level changes suggests an initial drowning at the base of BIIγ, immediately followed by a lowstand that in turn was succeeded by a moderate sea-level rise and then a significant fall. The last marks the BIIγ/BIIIα boundary. Correlation with sections in Scandinavia suggests that the basal part of BIIγ is strongly condensed.

scholarly journals The Sjælland Fjelde Formation: a new Ordovician formation from eastern North Greenland

1986 ◽  
Vol 132 ◽  
pp. 27-37
Author(s):  
J.R Ineson ◽  
J.S Peel ◽  
M.P Smith
Keyword(s):  
Shallow Water ◽  
North West ◽  
Middle Ordovician ◽  
The North ◽  
New Formation ◽  
North Greenland

The name Sjælland Fjelde Formation is introduced for a varied sequence of shallow-water platform dolomites and dolomitic limestones, about 105 m in thickness, in Kronprins Christian Land, eastern North Greenland. The new formation lies between the previously described Wandel Valley and Børglum River Formations. Conodont faunas indicate that the Sjælland Fjelde Formation is of Middle to earliest Late Whiterockian (early Middle Ordovician) age and that it can be eorrelated with the upper part of the Wandel Valley Formation of Peary Land to the north-west.

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