Sedimentology and depositional environments of Murihiku Supergroup sediments exposed in the Southland Syncline, New Zealand: Implications for reservoir potential in the Great South Basin

<p>A considerable amount is known about the biostratigraphy and organic geochemistry of the Murihiku Supergroup sediments exposed in coastal outcrops of the Southland Syncline, New Zealand. Much less work has been undertaken on the sedimentology of these strata, or understanding their depositional environments and depositional trends through time. What these implications are for reservoir prospectivity in the adjacent Great South Basin, has also had little study focused on it. This thesis addresses these issues by undertaking outcrop-based sedimentological and facies interpretations of these rocks, thin-section based petrographic composition and provenance analysis, augmented by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), as well as porosity and permeability measurements from outcrop core plugs. Petroleum industry seismic data has additionally enabled seismic facies mapping of Murihiku rocks in the offshore Great South Basin. Outcrop observations point to a progressive change in depositional setting, from shelf / upper slope settings during the Late Triassic, to base of slope turbidite deposition in the Early Jurassic. This transgression is followed by regression into fluvial settings in the youngest outcropping Murihiku rocks in the study of Middle Jurassic age. Petrographically the sandstones are feldspathic and lithic arenites and feldspathic and lithic wackes. Provenance suggests derivation from an evolving, intermediate arc that was becoming more siliceous through Late Triassic and Middle Jurassic time. Diagenesis is characterised by early calcite and chlorite precipitation which have almost completely destroyed any primary porosity. Any secondary micro porosity has subsequently been infilled through dissolution of framework grains and zeolitization. SEM and core plug porosity and permeability measurements corroborate the diagenetic changes observed petrographically, with only fluvial facies of Middle Jurassic (Upper Temaikan) age showing any measureable porosity or permeability. As a result, reservoir potential for the Late Triassic to Middle Jurassic, Murihiku Supergroup rocks analysed in this study is low. Younger Murihiku sandstones which are postulated to occur offshore in the Great South Basin are likely to be less influenced by burial diagenesis. As shown from North Island occurrences, these younger successions hold some potential.The reservoir potential for these youngest portions of the Murihiku succession therefore remains positive, both in the Great South Basin, as well as other frontier areas of Zealandia, and continue to provide an exploration target for the petroleum industry.</p>

Sedimentology and depositional environments of Murihiku Supergroup sediments exposed in the Southland Syncline, New Zealand: Implications for reservoir potential in the Great South Basin

<p>A considerable amount is known about the biostratigraphy and organic geochemistry of the Murihiku Supergroup sediments exposed in coastal outcrops of the Southland Syncline, New Zealand. Much less work has been undertaken on the sedimentology of these strata, or understanding their depositional environments and depositional trends through time. What these implications are for reservoir prospectivity in the adjacent Great South Basin, has also had little study focused on it. This thesis addresses these issues by undertaking outcrop-based sedimentological and facies interpretations of these rocks, thin-section based petrographic composition and provenance analysis, augmented by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), as well as porosity and permeability measurements from outcrop core plugs. Petroleum industry seismic data has additionally enabled seismic facies mapping of Murihiku rocks in the offshore Great South Basin. Outcrop observations point to a progressive change in depositional setting, from shelf / upper slope settings during the Late Triassic, to base of slope turbidite deposition in the Early Jurassic. This transgression is followed by regression into fluvial settings in the youngest outcropping Murihiku rocks in the study of Middle Jurassic age. Petrographically the sandstones are feldspathic and lithic arenites and feldspathic and lithic wackes. Provenance suggests derivation from an evolving, intermediate arc that was becoming more siliceous through Late Triassic and Middle Jurassic time. Diagenesis is characterised by early calcite and chlorite precipitation which have almost completely destroyed any primary porosity. Any secondary micro porosity has subsequently been infilled through dissolution of framework grains and zeolitization. SEM and core plug porosity and permeability measurements corroborate the diagenetic changes observed petrographically, with only fluvial facies of Middle Jurassic (Upper Temaikan) age showing any measureable porosity or permeability. As a result, reservoir potential for the Late Triassic to Middle Jurassic, Murihiku Supergroup rocks analysed in this study is low. Younger Murihiku sandstones which are postulated to occur offshore in the Great South Basin are likely to be less influenced by burial diagenesis. As shown from North Island occurrences, these younger successions hold some potential.The reservoir potential for these youngest portions of the Murihiku succession therefore remains positive, both in the Great South Basin, as well as other frontier areas of Zealandia, and continue to provide an exploration target for the petroleum industry.</p>

Stability of the bedrock of castle building for geotourism purposes

The geological structure of the Slovak Republic is very complex and varied. This fact in the course of centuries has had an impact on the castle buildings built here. The subsoil of these structures has different petrographic composition, tectonic disturbances and other geological complexities that threaten the stability of these structures and endanger the objects in their surroundings. In recent years, these structures have begun to receive deserved attention. In the past, the problems of severely disturbed blocks in the subsoil were mainly addressed and had to be rehabilitated for these reasons. These were mainly buildings whose subsoil is built with carbonate rocks. A perfect example of a long-term solution to these complex problems is also the Strecno Castle. A lot of effort and money has already been devoted to solving the stability of the bedrock, which also adversely affects the stability of the castle. However, the extensive set of works that have been carried out here over a long period of time have not brought a complete solution to the problems that occur here. For this reason, continuous work is being carried out here under the guidance of experts to eliminate the effects of erosion of the bedrock in particular. In the present work, the activities and measures that have been implemented here in stages up to the present are briefly described chronologically.

Material Composition of the Mesozoic Alkaline Rocks of the Yukhta Massif (Southern Yakutia, Central-Aldan Ore Region)

The paper considers the petrographic composition of the Mesozoic alkaline igneous rocks of the Yukhta massif. It is part of the Central Aldan ore region and is spatially located in the central part of the Nymnyr block. The massif is a large multiphase structure, of the most productive stage of the territory’s development – the Mesozoic tectonic-magmatic activation of the Aldan-Stanovoy shield. Determination of the qualitative quantitative-mineralogical characteristics of the 2 and 3 phases of intrusion (emplacement) most promising for gold-radioactive mineralization with the help of crystal-optical methods was the main goal of this work. As a result of petrographic studies of Mesozoic alkaline igneous rocks, it is defined that, the Yukhta massif is a multiphase magmatic structure, with decrease of the content of dark-colored minerals in rocks from the early to later phases of intrusion. In general, the rocks of the massif bear significant traces of secondary changes, which are related to the gradual formation of the massif. According to the features of the composition of the massif rocks, it was found that the latter could be formed from residual differentiates during the fractional crystallization of rock-forming minerals with the involvement of plagioclases. The Yukhta massif is associated with the large Samolazovskoye gold deposit, which formation is related to an intense contact-metasomatic impact on carbonate rocks. Hydrothermal-metasomatic transformations of the latter are the products of multi-stage silica-alkaline metasomatosis associated with the second and especially with the third phases of the massif intrusion, and with further weathering processes, involving karst formation, disintegration of gold-ore metasomatites and the formation of a thick oxidation zone. From whence it is concluded that uranium being a chemically active element does not accumulate in a hypergenic form within the Yukhta massif. Where the weathering crust is intensively developed, a gold-ore type of mineralization is observed. On the other hand, the rocks of the massif itself, in particular syenites of the 2 and 3 phases of intrusion, may be promising for the uranium-thorium-rare earth (U-Tn-REE) type of mineralization. In general, these studies in this direction will provide insight into a number of issues related to the study of the evolution and metallogeny of the Mesozoic tectonic-magmatic activation of the Aldan-Stanovoy Shield

Petrographic Composition of the Coal Within the Benue Trough, Nigeria, With a Consideration of the Paleodepositional Setting

The petrographic composition of coals hosted in the Benue Trough, Nigeria are presented and discussed in terms of paleodepositional setting that influenced the coal-bearing formations. The Benue Trough is a failed arm of the triple ‘RRr’ junction of an inland sedimentary basin that extends in a NE-SW direction from the Gulf of Guinea in the south, to the Chad Basin in the north. A total of twenty-nine (29) coal samples were obtained from 19 coal localities in the Upper (UBT), Middle (MBT), and Lower Benue Trough (LBT). The proximate data indicates the coal samples have a high volatile matter content, low ash yield, and high calorific value (24.82 MJ/Kg, on average). The sulphur values are generally low (average of 0.94 %). The coal samples are generally high in vitrinite, with an average of 59.3% by volume (mineral-matter free). Variation was noted in the inertinite content for the three sub-region samples. Liptinite macerals were not commonly observed in the studied samples and are absent in the MBT samples. The MBT coal samples reported a higher gelification index than the UBT and the LBT samples. Comparison of the array of coal facies models show the MBT samples are different from the UBT and LBT samples, concurring with the characterisation data. In view of the modified equations and the plots used, interpreting depositional environment accurately from just a single model is quite challenging.

Provenance controls on volcaniclastic beach sand: example from the Aeolian Archipelago, Mediterranean Sea

Sand and sandstone composition of volcanic origin may be clues to the provenance of the sediments and sedimentary rocks. Volcaniclastic provenance studies contribute significantly to unravel the sediment generation and provenance under investigation that in the Aeolian archipelago comprise preserved units of outcrops dominated by lava flows intercalated with air fall tephras as source rocks. The aim of this paper is the study of the petrographic composition and the textures of beach sands that may be used as a guide for the interpretation of provenance and origin of beach sand(stone)s rich in volcanic debris transported into deeper water. The composition of Aeolian beach deposits defines a single immature petrofacies with a high amount of unweathered glass and mafic minerals. Panarea island is dominated by dacites and new grain categories have been proposed to discriminate this provenance. Surface processes such as mechanical erosion (mass wasting and surface runoff) produce an overestimation of mafic components, with respect to the felsic ones in the beach sand fraction.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5608950

Petrography of bottom rock material

The Quaternary sediments of the Barents Sea contain a large amount of coarse clastic bottom rock material (BRM), with varying degrees of grain roundedness. Its study is important in determining the type and composition of the earth's crust, with paleogeographic constructions and revealing data on the dynamics of the ice cover. Studies of the Barents Sea BRM began in the 20s of the last century. During this period, were formed basically two hypotheses about the relationship between the distribution of BRM with elements of the sea topography and bedrock exposure. One of them considers BRM a marker suitable for identifying petrographic provinces at the bottom of the Barents Sea [Klenova, 1960]. In this chapter, on the basis of new up-to-date data obtained in 67 and 68 cruises of the RV Akademik Mstislav Keldysh in 2016–2017, the grain size, petrochemical and mineral compositions of BRM are estimated, their distribution patterns are given, transportation methods are analyzed and its feasibility is evaluated use in geological mapping. 4,193 samples were processed in Quaternary sediments, among which 86 reference types were identified. It was shown that the diversity of the composition of the Barents Sea BRM depends on glacial and ice-ice spacing. Therefore, the use of BRM for geological mapping of the bottom of the Barents Sea is unsuitable. The petrographic composition of the BRM in different regions of the Barents Sea is subject to significant fluctuations, but in general it is complementary to the set of rocks in the areas of demolition of adjacent land and depends on the extent of exaration and the removal of exaration material by the glacier to sedimentation areas.

Study of "Saralsk" Deposit for Practical Applications in Construction

In article the results of research of structural features and technical properties of andesite - basalt stone rock of the “Saralsk” deposit are given. The material is estimated by its mineral - petrographic composition, and the cuts/refinements of stone materials have been made for the microscopic study of mineral-petrographic composition. Researches are conducted according to requirements of acting standards and as a result, it became clear, that the rock consists basically of minerals opacitized hornblende and plagioclase, it doesn't contain any no secondary minerals such as hydroxides of iron, chlorites, epidote, quartz, saricite, etc. Petrographic researches have allowed to determine the species of stone rock. The density, strength, water resistance and frost resistance of stone rock are studied. The suitability of the material for practical application in construction, including for external works, is revealed.

Elaboration of indices complex and additional criterion of coals and charges quality evaluation for production and prediction of required and high quality coke

Coal raw material base of coking is the main factor characterizing the quality of coke. Therefore, it is very important to know technological properties and peculiarities of coals behavior in a charge during coking process for coals charge batching and coke quality control. One of the priority directions in study coals and charges is petrographic and reflectogram analysis, which enable to obtain data related to evaluation genuine (one-valued) technological properties of coals, coal blends and charges at production of coke of required quality. Using a broad material of study, including the one carried out by the authors of the article, a wide range of application of reflectogram analysis of coals, coals blends and charges in the coking production was shown. It was demonstrated also that application of the analysis enabled to exclude the problem of “twins”, to define the degree of genetic coals recoverability and coals grades or types relation in the mixtures for the coking. Based on the elaborated by the authors reflectogram criteria of charges for coking, a strategy of coals batching was proposed, which ensures production of metallurgical coke of required and high quality and safe running of coke ovens. Based on wide experimental studies of plastic-tough properties of coal charges, porosity of coke, its X-ray structure characteristics, strength and reaction ability, theoretical ideas were formed about mechanism of interaction in a charge of petrographically nonuniform coals comprising it during coking process, by using the proposed by the authors indices of coals nonuniformity. The indices of coals, comprising the charge, nonuniformity, differ by metamorphism degree (σR) and petrographic composition (σСК), explaining regularities of forming of quality of coke from the charge with participation of petrographically nonuniform coals. The package of the factors noted by the authors, revealed in the process of the study of coals, coals blends and charges, as well as quality of coke obtained from them, enabled to elaborate a complex index of charges coking ability (К.п.к.Vo), which enables to considerably simplify the mathematical model of coke quality prediction and to increase its reliability. Mathematical models of coke quality prediction were verified and implemented at several plants of Russia.