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Integrated geological and petrophysical investigation on carbonate rocks of the middle early to late early Canyon high frequency sequence in the Northern Platform area of the SACROC UnitIsdiken, Batur 18 February 2014 (has links)
The SACROC unit is an isolated carbonate platform style of reservoir that typifies a peak icehouse system. Icehouse carbonate platforms are one of the least well understood and documented carbonate reservoir styles due to the reservoir heterogeneities they embody. The current study is an attempt to recognize carbonate rock types defined based on rock fabrics by integrating log and core based petrophysical analysis in high-frequency cycle (HFC) scale sequence stratigraphic framework and to improve our ability to understand static and dynamic petrophysical properties of these reservoir rock types, and there by, improve our understanding of heterogeneity in the middle early to late early Canyon (Canyon 2) high frequency sequence (HFS) in the Northern Platform of the SACROC Unit. Based on core descriptions, four different sub-tidal depositional facies were defined in the Canyon 2 HFS. Identified depositional facies were grouped into three different reservoir rock types in respect to their rock fabrics in order for the HFC scale petrophysical reservoir rock type characteristic analysis. Composed of succession of the identified reservoir rocks, twenty different HFCs were determined within the HFC scale sequence stratigraphic framework. The overall trend in the HFCs demonstrate systematic coarsening upward cycles with high reservoir quality at the cycle tops and low reservoir quality at the cycle bottoms. It was observed in terms of systems tracts described within the cycle scale frame work that the overall stacking pattern for high stand systems tracts (HST) and transgressive systems tracts (TST) is aggradational. And, the reservoir rocks representing the HST are more porous and permeable than those of TST. In addition to that, it was detected that the diagenetic overprint on the HST reservoir rocks is more than that of the TST. According to the overall petrophysical observations, the grain-dominated packstone deposited during HST was interpreted as the best reservoir rock. Upon well log analysis on the identified reservoir rocks, some specific log responses were attributed to the identified reservoir rocks as their characteristic log signatures. / text
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The tectonic evolution and volcanism of the Lower Wyloo Group, Ashburton Province, with timing implications for giant iron-ore deposits of the Hamersley Province, Western AustraliaMuller, Stefan G. January 2006 (has links)
[Truncated abstract] Banded iron formations of the ~27702405 Ma Hamersley Province of Western Australia were locally upgraded to high-grade hematite ore during the Early Palaeoproterozoic by a combination of hypogene and supergene processes after the initial rise of atmospheric oxygen. Ore genesis was associated with the stratigraphic break between Lower and Upper Wyloo Groups of the Ashburton Province, and has been variously linked to the Ophthalmian orogeny, late-orogenic extensional collapse, and anorogenic continental extension. Small spot PbPb dating of in situ baddeleyite by SHRIMP (sensitive highresolution ion-microprobe) has resolved the ages of two key suites of mafic intrusions constraining for the first time the tectonic evolution of the Ashburton Province and the age and setting of iron-ore formation. Mafic sills dated at 2208 ± 10 Ma were folded during the Ophthalmian orogeny and then cut by the unconformity at the base of the Lower Wyloo Group. A mafic dyke swarm that intrudes the Lower Wyloo Group and has close genetic relationship to iron ore is 2008 ± 16 Ma, slightly younger than a new syneruptive 2031 ± 6 Ma zircon age for the Lower Wyloo Group. These new ages constrain the Ophthalmian orogeny to the period <2210 to >2030 Ma, before Lower Wyloo Group extension, sedimentation, and flood-basalt volcanism. The ~2010 Ma dykes present a new maximum age for iron-ore genesis and deposition of the Upper Wyloo Group, thereby linking ore genesis to a ~21002000 Ma period of continental extension similarly recorded by Palaeoproterozoic terrains worldwide well after the initial oxidation of the atmosphere at ~2320 Ma. The Lower Wyloo Group contains, in ascending order, the fluvial to shallow-marine Beasley River Quartzite, the predominantly subaqueously emplaced Cheela Springs flood basalt and the Wooly Dolomite, a shelf-ramp carbonate succession. Field observations point to high subsidence of the sequence, rather than the mainly subaerial to shallow marine depositional environment-interpretation described by earlier workers. Abundant hydro-volcanic breccias, including hyaloclastite, peperite and fluidal-clast breccia all indicate quench-fragmentation processes caused by interaction of lava with water, and support the mainly subaqueous emplacement of the flood basalt which is also indicated by interlayered BIF-like chert/mudstones and below-wave-base turbiditic mass-flows.
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Φυσική ραδιενέργεια των κλαστικών και ανθρακικών ιζημάτων στην περιοχή ανατολικά της Ηγουμενίτσας / Natural radioactivity of clastic and carbonate sediments located eastern of Igoumenitsas area (Western Greece)Αναγνωστούδη, Θωμαή 09 May 2012 (has links)
Η μεταπτυχιακή διατριβή με θέμα: «Φυσική Ραδιενέργεια των κλαστικών και ανθρακικών ιζημάτων στην περιοχή ανατολικά της Ηγουμενίτσας», έχει ως αντικείμενο την αναγνώριση, μελέτη και ανάλυση της φυσικής ραδιενέργειας των φυσικών ραδιονουκλιδίων U238, Th232, Ra226 και K40 στις κλαστικές αποθέσεις ηλικίας Μειοκαίνου (Ακουιτάνιο) και στις κλαστικές αποθέσεις των υποθαλάσσιων ριπιδίων Ηωκαίνου και Ολιγοκαίνου, και στο ποσοστό συγκέντρωσής τους στις παλαιότερες ανθρακικές και σύγχρονες κλαστικές ακολουθίες της περιοχής Νεράιδας Θεσπρωτίας, καθώς επίσης και στην ερμηνεία των αποτελεσμάτων ως προς την ταυτοποίηση της πηγής προέλευσής τους.
Η περιοχή μελέτης ανήκει στη λεκάνη Φιλιάτες-Παραμυθιάς Ηπείρου και αποτελεί τμήμα ενός εκ των φλυσχικών συγκλίνων, τα οποία αναπτύσσονται στη δυτική Ελλάδα μέσα στην Ιόνια ζώνη, εξαιτίας της δράσης των εσωτερικών επωθήσεων.
Η υπαίθρια δειγματοληψία πραγματοποιήθηκε στην ανθρακική και κλαστική ακολουθία, με τη συλλογή 45 συνολικά δειγμάτων, εκ των οποίων 8 ήταν ασβεστολιθικά, 18 ψαμμιτικά, 18 πηλιτικά και 1 σύγχρονης ποτάμιας άμμου. Η περιγραφή των ιζηματολογικών ενοτήτων βασίστηκε σε βιβλιογραφικά δεδομένα των γύρω περιοχών, καθότι δεν πραγματοποιήθηκαν ιζηματολογικές και γεωχημικές αναλύσεις. Οι κλαστικές ακολουθίες ταξινομήθηκαν βάσει του γεωλογικού χάρτη του Ι.Γ.Μ.Ε. φύλλο Φιλιάτες 1962-63, 1:50.000, ως αποθέσεις του Ανώτερου Φλύσχη ηλικίας Ακουιτανίου και αποθέσεις του Φλύσχη των Αγ. Πάντων ηλικίας Ηωκαίνου-Ολιγοκαίνου.
Στην κατεύθυνση της ραδιοχημικής έρευνας, πραγματοποιήθηκε μια σειρά από ραδιοχημικές αναλύσεις σε όλο των αριθμό των δειγμάτων, προκειμένου να εκτιμηθεί η συγκέντρωση ενεργότητας των φυσικών ραδιονουκλιδίων των ανθρακικών και κλαστικών ακολουθιών, με σκοπό να εντοπιστεί η πηγή προέλευσής τους και η δυνατότητα αποθήκευσής τους, στους συγκεκριμένους σχηματισμούς. Η μέτρηση της συγκέντρωσης ενεργότητας του 238U, 226Ra, 232Th, και 40K έγινε με τη μέθοδο της γ-φασματομετρίας, με τη χρήση υπερκάθαρου ανιχνευτή γερμανίου (HPGe) της Canberra.
Ο κύριος στόχος αυτής της προσπάθειας, ήταν να διαπιστωθεί η ύπαρξη των φυσικών ραδιονουκλιδίων στην ανθρακική ακολουθία, καθώς και η συγκέντρωσή τους στην κλαστική ακολουθία, λόγω δευτερογενούς μετανάστευσής τους, από τις ήδη ταυτοποιημένες φωσφορούχες αποθέσεις των γειτονικών περιοχών.
Η περιοχή μελέτης δεν εμφάνισε υπερβολικές τιμές συγκέντρωσης ενεργότητας φυσικών ραδιονουκλιδίων σε κανέναν από τους γεωλογικούς σχηματισμούς που ερευνήθηκαν. Η ανθρακική ακολουθία της περιοχής χαρακτηρίστηκε πολύ φτωχή στα υπό μελέτη φυσικά ραδιονουκλίδια, σε αντίθεση με την κλαστική ακολουθία, η οποία εμφάνισε γενικά αυξημένες τιμές συγκέντρωσης ενεργότητας φυσικών ραδιονουκλιδίων. Τέλος, βάσει των συγκεντρώσεων που εντοπίστηκαν στις σύγχρονες ποτάμιες προσχώσεις της περιοχής μελέτης, τα Τεταρτογενή ιζήματα της περιοχής χαρακτηρίστηκαν ως αρκετά εμπλουτισμένα, συμπεραίνοντας την ύπαρξη σύγχρονης τροφοδοσίας φυσικών ραδιονουκλιδίων μέσω οριζόντιων ρηγμάτων.
Συμπεραίνοντας, οι κλαστικές ακολουθίες του Φλύσχη των Αγ. Πάντων, Ηωκαίνου και Ολιγοκαίνου και τα Τεταρτογενή ιζήματα της περιοχής, δεν χαρακτηρίζονται ως άμεσα προτεινόμενοι σχηματισμοί για τη χρήση αδρανών υλικών, ενώ προτείνεται εκτενέστερη μελέτη στους Τεταρτογενείς σχηματισμούς της Εξωτερικής Ιονίου. / The subject of postgraduate thesis «Natural radioactivity of clastic and carbonate sediments located eastern of Igoumenitsas area (Western Greece)» is dealing with the recognition, study and analysis of natural radioactivity of natural radionuclides U238, Th232, Ra226 και K40 in the Miocene (Aquitanian) clastic deposits, Eocene and Oligocene clastic deposits of the submarine fans and their concentration amount in the older carbonate and contemporary clastic sequences of the study area located in the village Neraida of Thesprotia. It also deals with the interpretation of results in terms of the identification of the source.
The study area is located in the basin of Filiates-Paramithia of Epirus and constitutes a part of the flysch syclins, developed in Western Greece within the Ionian zone, due to the activity of internal thrusts.
The sampling was accomplished in the carbonate and clastic sequences, with the collection of 45 rock samples: 8 limestones, 18 sandstones, 18 siltstones and 1 sample of contemporary fluvial sand. The sedimentological units description was based in bibliographical data, since sedimentological and geochemical analyses were not accomplished. The clastic sequences were classified based on the geological map of I.G.M.E. Filiates sheet 1962-63, 1:50.000, as Upper Flysch depotites Aquitanian ages and Ag. Panton Flysch deposites Eocene-Oligicene ages.
Towards the radiochemical research a sequence of radiochemical analyzes were accomplished, in order to evaluate the activity concentration of natural radionuclides of carbonate and clastic sequences, with the aim of locating their source and the potential of their storage in these specific formations. The activity concentration measurement of 238U, 226Ra, 232Th, and 40K was carried out with gamma-spectometry method, using the High Purity Germanium detector (HPGe) of Canberra Company.
The main aim of this effort was the establishment of the existence of the natural radionuclides in the carbonate sequence, as well as their concentration in the clastic sequence, due to their secondary migration from the already identified phosphatic deposits of the adjacent areas.
None of the studied geological formations of the study area presented exaggerating activity concentration of natural radionuclides values. The carbonate sequence in terms of the studied natural radionuclides was characterized as quite poor, contrasting to the clastic sequence, which generally showed increasing activity concentration of natural radionuclides values. Finally, based on the concentrations traced in the contemporary fluvial deposits of the study area, the Quaternary sediments of the area were characterized as sufficiently enriched, concluding to the existence of contemporary source of natural radionuclides through horizontal faults.
Concluding, the Eocene – Oligocene clastic sequences of Ag. Panton Flysch and the Quaternary sediments of the area, are not characterized as immediately preferred formations for the usage of aggregate materials, while additionally a more extensive research in the Quaternary formations of External Ionian Zone is suggested.
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Sequence Stratigraphy of the Bridal Veil Falls Limestone, Carboniferous, Lower Oquirrh Group, on Cascade Mountain, Utah: A standard Morrowan Cyclostratigraphy for the Oquirrh BasinShoore, David Joseph 21 March 2005 (has links) (PDF)
The Bridal Veil Falls Limestone (lowest 400 meters of the Permo-Carboniferous Oquirrh Group) is well exposed on the flanks of Cascade Mountain (Wasatch Front and adjacent mountain ranges) near Provo, Utah. Because of its excellent exposure and location in the heart of the Oquirrh depocenter, this area was selected to develop a sequence stratigraphic framework for Morrowan rocks that may be applied throughout the Oquirrh basin (NW Utah and southern Idaho) as well as the adjacent Ely and Bird Springs troughs. Eleven partial to complete sections of the Bridal Veil Falls Limestone were measured along the west and north flanks of Cascade Mountain and the south end of Mt. Timpanogos. There the limestone is comprised principally of mud-rich carbonate lithofacies punctuated by thin, and sometimes discontinuous quartzose sandstone beds. The predominance of muddy to grain-rich heterozoan limestone microfacies suggests deposition on a west-dipping low energy carbonate ramp that prograded westward throughout Morrowan time. Sandstones reflect transport of siliciclastics from the incipient Weber shelf (located to the NE) during episodes of sea-level lowstand. The Bridal Veil Falls Limestone is subdivided into 21, third and fourth order depositional sequences ranging in thickness from 3 to 60 meters, and 62 parasequences. Parasequences are commonly asymmetrical, reflecting rapid flooding followed by protracted shoaling and/or sea level drop. Selected cycles are recognized in the Lake Mountains, Thorpe Hills, and the southern Oquirrh Mountains to the west of Cascade Mountain indicating that Parasequences delineated at Cascade Mountain are regionally extensive over an area of at least 300 square kilometers.
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