scholarly journals Neoproterozoic microbially-induced sedimentary structures (MISS) from Ediacaran Podillya Basin, Ukraine: mineralogical particularity and paleoenvironmental application

2019 ◽  
Vol 28 (3) ◽  
pp. 554-561
Author(s):  
Y. Soldatenko ◽  
A. El Albani ◽  
C. Fontaine ◽  
V. A. Nesterovsky ◽  
M. V. Ruzina
Keyword(s):  
Sedimentary Basin ◽  
Microbiological Activity ◽  
Sedimentary Structures ◽  
Diagenetic Processes ◽  
Coastal Marine ◽  
Bacterial Mats ◽  
The Difference ◽  
Biological Films ◽  
Host Rocks ◽  
Siliciclastic Sediments

The Neoproterozoic Podillya sedimentary Basin is well known to the imprints of the Ediacaran soft-bodied fauna which were previously described by many ukrainian and foreign authors. At this period, fossil-rich siliciclastic sediments recognized as traces of early metazoans also contain evidence of significant microbiological activity. In these ediacaran sediments, many structures can be interpreted as microbially induced sedimentary structures (MISS). Their morphologies have a great similarity with modern structures observed in relation with micro-organism activity. These specific structure and surfaces and their mineral composition are the criteria used to study the bacterial structures from the ukrainian Neoproterozoic sedimentary basin. Our results demonstrate microorganisms were organized in bacterial mats whose activity was recorded in the difference of mineralogy between biological films and host rocks. On outcrop, the different type of MISS are often associated with lenticular beddings, ripples and hummocky cross structures indicative of coastal-marine conditions close to the littoral zone of the basin at    this epoch. If MISS are important in the issue of paleogeographic reconstructions, they also give precious informations about early diagenetic processes, syn- and post-sedimentation. By mineralogical approach we show that during the time of development of MISS structures and the burial that followed the diagenetic processes have remained moderate. Finally, the close coexistence with ediacarian fossils suggest that such bacterial mats could be at the origin of the fossilization process of soft-bodies of enigmatic Ediacaran biota of Mohyliv-Podylska Group and their preservation until today.

scholarly journals The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben

2003 ◽  
Vol 1 ◽  
pp. 349-366 ◽  
Author(s):  
Ida L. Fabricius ◽  
Louise Dahlerup Fazladic ◽  
Armgard Steinholm ◽  
Uffe Korsbech
Keyword(s):  
Middle Jurassic ◽  
Gamma Ray ◽  
Clay Content ◽  
Heavy Minerals ◽  
Reservoir Evaluation ◽  
Fine Grained ◽  
Natural Gamma ◽  
The Difference ◽  
Siliciclastic Sediments ◽  
Quartz Grains

Danish Central GrabenA cored sandstone interval from the Middle Jurassic Harald Field of the Danish North Sea was chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with the purpose of determining how the Spectral Natural Gamma (SNG) log could be used as an indicator of reservoir quality. Core intervals of quartz arenites and quartz wackes were selected. Although no linear relationship was found between clay content and potassium (K), thorium (Th), or uranium (U), the K content characterises three discrete lithofacies. Lithofacies I has a grain-supported texture, with a predominance of quartz grains; only minor fine-grained matrix is present. Sandstones of lithofacies I have a low K content and most of the K is hosted in feldspar. Porosity varies between 23% and 28% and permeability is in the range 200–2000 mD. Lithofacies II sandstones have a grain-supported texture, with a predominance of quartz grains; fine-grained matrix fills the intergranular volume. Sandstones of lithofacies II have an intermediate K content, with K-feldspar, mica, and illite as the main sources. Porosity varies between 11% and 17% and permeability is in the range 0.4–25 mD. Lithofacies III has a matrix-supported texture with quartz grains floating in a clay-rich matrix. Samples from lithofacies III have the highest K signal. Illite and illitised kaolinite are roughly equal in importance as sources of K. Porosity is up to 11% and permeability up to 0.5 mD. The Th and U content of all lithofacies is governed primarily by the presence of heavy minerals; no apparent general relationship between U and Total Organic Carbon (TOC) was found. Comparisons between the core measurements of K, Th, and U, and the SNG log disclosed a discrepancy between the calibrations of laboratory and borehole measurements. For U the discrepancy contains an erratic element, whereas the difference for K and Th can be eliminated by correction factors. Thus, the conclusions based on laboratory measurements appear to be applicable to the log data, and, using corrected K values, the facies subdivision can be extended throughout the reservoir section based on the SNG log.

scholarly journals Coupled experimental/numerical workflow for assessing quantitative diagenesis and dynamic porosity/permeability evolution in calcite-cemented sandstone reservoir rocks

2018 ◽  
Vol 73 ◽  
pp. 36 ◽  
Author(s):  
Steven Claes ◽  
Fadi H. Nader ◽  
Souhail Youssef
Keyword(s):  
Permeability Evolution ◽  
Flow Properties ◽  
New Approach ◽  
Reservoir Rocks ◽  
Pore Blocking ◽  
Diagenetic Processes ◽  
Porosity And Permeability ◽  
Sandstone Reservoir ◽  
Calcite Cement ◽  
Host Rocks

Some of the world best hydrocarbon reservoirs (carbonates and siliciclastics) are also believed to be valuable for subsurface storage of CO2 and other fluids. Yet, these reservoirs are heterogeneous in terms of their mineralogy and flow properties, at varying spatial-temporal scales. Therefore, predicting the porosity and permeability (flow properties) evolution of carbonates and sandstones remains a tedious task. Diagenesis refers to the alteration of sedimentary rocks through geologic time, mainly due to rock-fluid interactions. It affects primarily the flow properties (porosity and permeability) of already heterogeneous reservoir rocks. In this project a new approach is proposed to calculate/quantify the influence of diagenetic phases (e.g. dissolution, cement plugging) on flow properties of typical sandstone reservoir rocks (Early Jurassic Luxembourg Formation). A series of laboratory experiments are performed in which diagenetic phases (e.g. pore blocking calcite cement in sandstone) are selectively leached from pre-studied samples, with the quantification of the petrophysical characteristics with and without cement to especially infer permeability evolution. Poorly and heavily calcite-cemented sandstone samples, as well as some intermediate cemented samples were used. The results show a distinctive dissolution pattern for different cementation grades and varying Representative Elementary Volumes (REVs). These conclusions have important consequences for upscaling diagenesis effects on reservoirs, and the interpretation of geochemical modelling results of diagenetic processes. The same approach can be applied on other type of cements and host-rocks, and could be improved by integrating other petrophysical analyses (e.g. petroacoustic, NMR).

Laboratory Measurement of Low-Permeability Rocks With a New Flow Pump System

1997 ◽  
Vol 506 ◽  
Author(s):  
Ming Zhang ◽  
Manabu Takahashi ◽  
Tetsuro Esaki
Keyword(s):  
Pore Pressure ◽  
Fluid Pressure ◽  
Confining Pressure ◽  
Test System ◽  
Low Permeability ◽  
Specific Storage ◽  
Pump System ◽  
The Difference ◽  
Host Rocks ◽  
Flow Pump

ABSTRACTNearly impermeable host rocks have been recognized as favorable media for many kinds of underground utilization such as radioactive nuclear waste disposal, storage of oil and LP gas, and CAES. To properly evaluate the ability of a geologic medium to retard transmission of fluids, it is necessary to accurately measure its hydraulic properties, most notably the permeability and specific storage. This paper presents a new flow pump permeability test system capable of testing low-permeability rocks under high confining and high pore pressure conditions, which simulate ground pressures at large depths. The new system was used to test the Inada Granite from Japan. The results of present study show that: 1) both permeability and specific storage of the rock are dependent not only on the confining pressure but also on the pore pressure. They decrease with the increment of the effective confining pressure, i.e., the difference between confining and pore pressures; 2) the permeability and specific storage of Inada Granite range from 10−11 to 10−12 cm/s and 10−6 to 10−7 1/cm, respectively. The flow pump technique with its rigorous theoretical analysis can be used to effectively obtain such low permeabilities within several tens of hours; 3) the storage capacity of flow pump system itself decreases with the increment of fluid pressure within the permeating system.

scholarly journals Sedimentological observations in middle and late Triassic rocks, Jameson Land Basin, central East Greenland

1976 ◽  
Vol 80 ◽  
pp. 106-110
Author(s):  
L.B Clemmensen ◽  
F Andreasen
Keyword(s):  
Sedimentary Basin ◽  
Late Triassic ◽  
Land Area ◽  
Detailed Measurement ◽  
East Greenland ◽  
Sedimentary Structures ◽  
Preliminary Account ◽  
Field Season

The middleand late Triassic rocks of Jameson Land and the nearby part ofthe Scoresby Land area in central East Greenland (fig. 33) were studied during the 1975 field season as part of a 2½-year joint GGU-University of Copenhagen project. The work entailed the detailed measurement of several sedimentological sections. Emphasis was laid on the primary sedimentary structures and a large number ofpalaeocurrent measurements were carried out. The ultimate goal of this approach is to understand the palaeogeographical evolution ofthe sedimentary basin during middle and late Triassic time. This note is a preliminary account and delineates only the sedimentary history ofthe basin in very broad terms.

Barite nodules of possibly late diagenetic origin from Twitya River area, Mackenzie Mountains, Northwest Territories

1976 ◽  
Vol 13 (10) ◽  
pp. 1446-1455 ◽  
Author(s):  
Peter Laznicka
Keyword(s):  
Northwest Territories ◽  
Sedimentary Basin ◽  
Late Phase ◽  
Tectonic Deformation ◽  
Carbonate Concretions ◽  
Laramide Orogeny ◽  
Quartz Monzonite ◽  
Carbonaceous Shales ◽  
Mackenzie Mountains ◽  
Host Rocks

Conspicuous spherical and subspherical barite nodules occur in Devonian(?)/Mississippian carbonaceous shales and argillaceous dolomitic limestones in Twitya river area (western foothills of the Backbone Ranges, Mackenzie Mountains, N.W.T.).The majority of barite nodules are spherulitic, composed of grey radiating barite crystals. The microscopic study of barite and of sedimentary fabrics in its host rocks has demonstrated that the crystallization of nodules was a late diagenetic event postdating the formation of carbonate concretions in shales, dolomitization, and the early phase of fracturing, but predating the late phase of fracturing and tectonic deformation. The nodules have clearly developed by replacement of their carbonate host.The middle to late Paleozoic, black shale sequence that occurs on both sides of the Yukon – Northwest Territories boundary at the latitude of Macmillan Pass (Canol road) appears to be in a distinct barite province with numerous occurrences of mostly bedded barite recorded. The presently available evidence indicates that the introduction of barium into the sedimentary basin had probably been syndepositional, followed by diagenetic concentration and barite emplacement well before the 'Laramide Orogeny' and the emplacement of Cretaceous quartz monzonite stocks.

scholarly journals Petrography of the Mesozoic Alkaline Rocks of the Taezhniy Massif (South Yakutia, Aldan-Stanovoy Shield, Leglier Ore Cluster)

2021 ◽  
Vol 906 (1) ◽  
pp. 012115
Author(s):  
Michil Ivanov ◽  
Aleksey Ivanov ◽  
Anatolii Zhuravlev
Keyword(s):  
The Body ◽  
Second Phase ◽  
Optical Studies ◽  
Two Phase ◽  
Small Bodies ◽  
The Difference ◽  
Two Phases ◽  
Host Rocks ◽  
Late Stages ◽  
Syenite Porphyry

Abstract The article is concerned with the petrographie compositions of the Mesozoic alkaline igneous rocks of the Taezhniy massif and its small bodies (dikes). The Taezhniy massif is located in the central part of the Nimnyr block (Aldan-Stanovoy shield). According to our field observations, it was first determined that the Taezhniy massif has a two-phase structure, its rocks of contain syenite-porphyry and leucocratic syenites. The rocks of the massif intrude the Archean granites, and are themselves intruded by late dikes of bostonites and vogesites. Based on petrographic studies, we also identified two phases of intrusion in the Taezhniy massif – syenite-porphyry and leucocratic syenites. The difference of them is as follows: in the syenite-porphyry rocks, plagioclase predominates over K-feldspar, and the content of dark-colored minerals reaches 10%. The rocks of the second phase are characterized by the predominance of K-feldspar over plagioclase, with the content of dark-colored minerals up to 5%. The order of intrusion of the massif formations is determined by the presence of xenoliths of syenite-porphyry rocks in leucocratic syenites. The rocks of the bostonite dike cutting the massif are characterized by the absence of amphibole and an increased content of pyroxene. This is most likely due to the fact that, the rock contains xenoliths of the host rocks of biotite-pyroxene composition. The dikes also conyain xenoliths of the second phase rocks, which indicates a later age of this dike. The bostonite dike located in the immediate vicinity of the massif is almost identical to the dike found in the massif, except an amphibole in the composition of the rocks. The only dike of vogesites that intersects the body of the massif is characterized by the presence of two varieties of amphibole: common hornblende and a sufficient amount of barkevikite, which phenocrysts stand out clearly against the background of the total microcrystalline mass. Also, in the course of crystal-optical studies, it was noted that in the structure of the massif there is an increase in the leucocratic magmatism from the early phase to the late, but with a decrease in this indicator, taking into account the introduction of vogesite dikes at the late stages of magmatism development. Based on this, the conclusion is made about the antidromic development of the rocks of the Taezhniy massif. When comparing the evolution of magmatism of the Taezhniy massif with the Ryabinoviy massif, a possible gold-ore specialization of the studied object is suggested.

Early diagenetic processes in coastal marine sediments disturbed by a catastrophic sedimentation event

2002 ◽  
Vol 66 (14) ◽  
pp. 2547-2558 ◽  
Author(s):  
Bruno Deflandre ◽  
Alfonso Mucci ◽  
Jean-Pierre Gagné ◽  
Constance Guignard ◽  
B.jørn Sundby
Keyword(s):  
Marine Sediments ◽  
Coastal Marine Sediments ◽  
Diagenetic Processes ◽  
Coastal Marine

A quantitative assessment of the diel influence on the cryptobenthic fish assemblage of the shallow Mediterranean infralittoral zone

2020 ◽  
Vol 84 (1) ◽  
pp. 49
Author(s):  
Igor Glavičić ◽  
Marcelo Kovačić ◽  
Alen Soldo ◽  
Ulrich Schliewen
Keyword(s):  
Fish Assemblage ◽  
Fish Assemblages ◽  
Fish Diversity ◽  
Diel Variation ◽  
Coastal Marine ◽  
Benthic Fishes ◽  
Coastal Marine Ecosystems ◽  
The Difference ◽  
Habitat Variables ◽  
Cryptobenthic Fishes

Cryptobenthic fishes are an underestimated and probably important component of coastal marine ecosystems that are usually overlooked by standard methods for collecting and studying benthic fishes. Studies focusing on cryptobenthic fishes have been rare and all have been based on samples taken during daytime. The present study tested the difference in epibenthic and cryptobenthic fish composition, diel differences in cryptobenthic fish assemblage and diel shifts of infralittoral fish species between hidden and open bottom spaces. It also looked for the significant habitat variables structuring the cryptobenthic fish assemblage. The daylight, sunset and night samples of epibenthic and cryptobenthic fish assemblages were collected from 78 squares of 1 m2 shallow water plots (0.5 to 3 m) on Brač island in the eastern Adriatic. The study recorded 27 species, among which the family Gobiidae dominated fish diversity with 14 species. Cryptobenthic specimens highly outnumbered epibenthic specimens, with a ratio of 7.5 to 1. Species composition of cryptobenthic and epibenthic fish assemblages differed significantly. No diel variation in composition, species richness or abundance of the cryptobenthic fish assemblage was detected. Occurrence frequencies in hidden and open bottom spaces of ambivalent species did not change significantly between times of day, so no dial switches between open and hidden places were apparent. In combination, these results suggest that the cryptobenthic fish assemblage has diel stability and is mostly composed of permanent inhabitants of hidden spaces with domination of miniature gobies. Significant habitat variables for species occurrence were the presence of multiple layers, bottom inclination and the presence of cobbles, while depth also had a large but not significant effect.

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