Dissertations / Theses: 'Stratigraphie – Iran'

1

Hemmati, Soheil. "Stratigraphy and bio-event studies of the Guadalupian - Lopingian boundary in the northern margin of Sanandaj-Sirjan Zone, Central Iran and North-West of Iran." Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS011.pdf.

Full text

Abstract:

La position de la limite Guadalupien - Lopingien (GLB) a longtemps été un sujet de controverse Parmi les nombreuses coupes étudiées, trois régions spécifiques : Julfa (coupe d'Ali-Bashi), Tabas (coupe de Bagh-e-Vang) et Abadeh (coupe de Baghuk) ont été choisies pour une étude ciblée. La coupe d'Ali-Bashi a fait l'objet d'un échantillonnage et d'une vaste collecte de plus de 240 échantillons de roche sur une épaisseur mesurée de 189 mètres et dans la coupe de Bagh-e-Vang, plus de 160 échantillons sur 200 mètres d'épaisseur dans la Formation de Jamal. L'échantillonnage de la section Baghouk a rencontré des obstacles spécifiques qui ont entravé notre progression, notamment : les conditions climatiques, la crise économique en Iran et la pandémie de covid-19. Une étude lithostratigraphique très détaillée de la Formation de Khachik sur la coupe d'Ali-Bashi a permis d'identifier 14 unités rocheuses distinctes au sein des trois membres principaux. Ceci permet un nouvel inventaire lithostratigraphique de ces séquences, qui peut être compré avec les recherches existantes sur la Formation de Khachik. De plus, dans la section Bagh-e-Vang, 10 unités de la Formation de Jamal appartenant aux trois membres ont également été identifiées. De plus, des méthodes d'extraction, au CH₂O₂, au CH₃COOH, l'acétolyse à chaud et les protocoles à l'HF, ont été testées pour l'extraction des microfossiles. Après d'importants efforts de préparation et un protocole soigneusement élaboré destiné à l'obtention de conodontes, l'application des techniques CH₂O₂ et CH₃COOH, les coupes d'Ali-Bashi et Bagh-e-Vang, n'ont pas livré de conodontes. Trois autres méthodes ont été testées pour l'extraction d'ostracodes sur des échantillons de la coupe d'Ali-Bashi. Les échantillons ont été préparés avec de l'acide formique à 10 % (CH₂O₂) et de l'acide acétique à 15 % (CH₃COOH). Le protocole CH₂O₂ a été productif avec des ostracodes bien conservés, avec dix taxons dans des calcaires dolomitisés durs, tandis que les autres processus (CH₃COOH à froid) n'ont rien donné. L'application du protocole d'acétolyse à chaud s'est avérée efficace pour extraire une quantité importante de carapaces d'ostracodes bien conservées, conduisant à l'identification d'un total de 56 espèces. La technique à l'HF dans le traitement de 12 échantillons de cherts des coupes d'Ali-Bashi et Bagh-e-Vang n'a pas permis d'isoler de radiolaires. L'analyse des microfaciès dans la coupe d'Ali-Bashi a permis d'identifier 15 microfaciès distincts subdivisés en 28 sous-microfaciès. L'assemblage de groupes de microfaciès sont de MKL1 à MKL2 (milieu lagunaire), de MKR2 à MKR3 (restreint) présente des caractéristiques d'un cadre restreint de rampe intérieure, MKO1 à MKO4 (marine ouvert) en zone de rampe interne. Les microfaciès MKM1 à MKM3 se sont déposés dans un environnement marin ouvert, dans les zones de la rampe médiane, tandis que MKT1 à MKT3 ont été identifiés dans les parties inférieures de la rampe extérieure, correspondant à la position du pied de pente de la plate-forme carbonatée. De plus, en se rapportant aux microfaciès standards défnis par Flugel (2010), l'étude propose 10 microfaciès de type RMF, ainsi que leurs 4 SMF correspondants. De plus, sur la base des zones de faciès standard (ZF) introduites par Wilson (1975), trois ZF présentant une tendance ascendante peu profonde, à savoir FZ8, FZ7 et FZ3, ont été délimitées avec succès
The position of the Guadalupian-Lopingian Boundary (GLB) has long been a subject of contention among researchers. Among the numerous sections investigated, three specific regions Julfa (Ali-Bashi section), Tabas (Bagh-e-Vang section), and Abadeh (Baghuk section) have been chosen for focused study in this project. The Ali-Bashi section where sampling and an extensive collection of over 240 rock samples from a measured thickness of 189 meters and in the Bagh-e-Vang section a meticulous effort resulted in the collection of more than 160 rock samples from an outcrop measuring 200 meters in thickness in the Jamal Formation. Sampling the Baghuk section, encountered specific obstacles that impeded our progress including: climatic conditions, economic crisis in Iran and covid-19 pandemic. High-detailed lithostratigraphical investigation of the Khachik Formation in the Ali-Bashi section, led to identified 14 distinct rock units within the three main members. This discovery has the potential to stimulate the creation of a new lithostratigraphic inventory for these sequences, which can be aligned with the existing background research on the Khachik Formation in this particular section. Furthermore, in the Bagh-e-Vang section, 10 rock units from Jamal Formation strata's belonging to the three members have also been identified. Moreover, Various extraction methods, including CH₂O₂, CH₃COOH, hot acetolysis, and HF protocols, were evaluated for the isolation of microfossils. After extensive preparation efforts and carefully crafted protocol intended for conodont element identification, applying both the CH₂O₂ and CH₃COOH techniques, in the Ali-Bashi and the Bagh-e-Vang sections were not achieved any conodonts. Three other methods were tested for ostracod extraction from Ali-Bashi section samples. The samples were prepared with cold 10% formic acid (CH₂O₂) and 15% acetic acid (CH₃COOH). The CH₂O₂ protocol was productive with well-preserved ostracods, allowed us to determine ten taxa were obtained exclusively through the diluted CH₂O₂ protocol from the hard dolomitized limestones, while the other cold CH₃COOH procedures were unsuccessful. The application of the hot acetolysis protocol proved successful in extracting a significant quantity of excellently preserved ostracods, leading to the identification of a total of 56 species. Despite our unwavering commitment to the recommended protocol applied the HF technique in the processing of 12 cherty samples obtained from the Ali-Bashi and Bagh-e-Vang sections yielded a disheartening outcome for the radiolarian microfossils. Microfacies analysis in the Ali-Bashi section led to identified 28 sub-microfacies which, derived with 15 distinct microfacies. The assemblage of microfacies groups are, ranging from MKL1 to MKL2 (lagoonal environment), MKR2 to MKR3 (restricted), MKO1 to MKO4 (open-marine) of the inner ramp zone. The MKO1 to MKO4, suggests a confined setting, occurring in the final part of the inner ramp under an open marine environment. Microfacies groups MKM1 to MKM3 are inferred to have been deposited in open marine environment, within the mid-ramp zones, whereas MKT1 to MKT3 were identified in the basal parts of the outer ramp, corresponding to the lower part of the slope within the carbonate shelf setting. Additionally, adhering to the standard microfacies designated by Flugel (2010), the study proposes 10 microfacies of the RMF type, along with their corresponding 4 SMFs for the studied strata. Besides, based on the standard facies zones (FZ) introduced by Wilson (1975), three FZs exhibiting a shallowing-upward trend, namely FZ8, FZ7, and FZ3, have been successfully delineated

APA, Harvard, Vancouver, ISO, and other styles

2

Taati, Qorayem Farid. "Stratigraphie séquentielle de systèmes carbonates dans un contexte tectonique actif : le groupe de Bangestan (Albien - Turonien) dans le Zagros (Iran)." Bordeaux 3, 2005. http://www.theses.fr/2005BOR30001.

Full text

Abstract:

Cette étude porte sur les systèmes carbonatés Albien à Turonien (Groupe Bangestan) de la marge orientale de la plaque arabe, qui affleure dans les montagnes du Zagros au sud-ouest de l'Iran. Les objectifs de cette étude sont les suivants : (1) la reconnaissance de l'organisation stratigraphique haute-résolution de ces systèmes à partir de l'étude d'un affleurement de qualité exceptionnelle dans le haut Zagros, (2) la corrélation stratigraphique des séquences définies à l'affleurement le long de deux grands transects régionaux dans le sud-ouest de l'Iran, et (3) la comparaison du modèle stratigraphique iranien avec les systèmes crétacés équivalents de la plaque arabe (Oman, Emirats, Iraq). Cette étude est basée sur l'analyse de 11 coupes d'affleurement et de quatorze logs de forages pétroliers (± paléologs α) : analyses paléontologiques semi-quantitatives, analyses sédimentologiques de faciès et microfaciès, analyses géochimiques des isotopes du carbone et de l'oxygène. L'intégration de l'ensemble de ces données a été utilisée pour établir un modèle de stratigraphie séquentielle haute-résolution. Les résultats de cette étude montrent l'existence de deux types de système carbonaté durant la période considérée : un système de type rampe riche en Orbitolines durant l'Albien inférieur (équivalent de la Formation Kazhdumi) et un système de type plate-forme barrée à rudistes et bassin intrashelf adjacent de l'Albien supérieur au Turonien (Formation Sarvak). La Formation Sarvak comprend quatre séquences de dépôt de troisième ordre. Sur des affleurements d'échelle subsismique, ces séquences montrent une organisation complexe en particulier pour ce qui concerne la géométrie des prismes de bas niveau marin et l'architecture des dépôts à la transition plate-forme bassin intrashelf. Ces séquences ont été reconnues régionalement et corrélées sur plusieurs centaines de kilomètres, renforçant ainsi la validité du modèle stratigraphique établi. Ces séquences sont également identifiées à l'échelle de plate-forme arabe grâce à des corrélation fiables avec les séries d'Oman et des Emirats, et, avec une précision moindre, avec celles d'Iraq. La zone d'affleurement étudiée fournit un analogue de première classe pour ce qui concerne le modèle de dépôt, le découpage séquentiel au 3ʿ ordre et l'organisation stratigraphique de la Formation Sarvak. Il pourra ainsi servir de modèle de référence pour le Zagros mais aussi pour une large partie du Moyen-Orient.

APA, Harvard, Vancouver, ISO, and other styles

3

Shahidi, Alireza. "Evolution tectonique du nord de l'Iran (Alborz et Kopet-Dagh) depuis le Mésozoïque." Paris 6, 2008. http://www.theses.fr/2008PA066249.

Full text

Abstract:

A partir d’études structurales, de paléocontraintes, subsidence et biostratigraphie, nous proposons un modèle d'évolution tectonique du nord de l'Iran depuis le Trias et l’orogenèse éo-cimmérienne (collision blocs cimmériens-Laurasie). Une extension NNE-SSW (failles normales synsédimentaires dans le Shemshak Trias sup. -Jurassique inf. ) est liée à la phase de rifting précédant l'ouverture du bassin Sud-Caspien (BSC), contemporaine des formations carbonatées Dalichai et Lar (Bajocien sup. -Néocomien). La formation de Tiz-Kuh (fin Barrémien-Aptien) est discordante (tardi-cimmérien) sur les séries mésozoïques antérieures. Le Crétacé sup. Débute par un épisode magmatique alcalin qui se poursuit jusqu’au Santonien. Le passage Crétacé-Paléogène est marqué par une discordance régionale liée à une inversion de la marge sud des bassins. Pendant l'Eocène inférieur à moyen, les failles normales synsédimentaires E-W à WNW-ESE sont fréquentes dans le Karaj (bassin d’arrière-arc très subsident).

APA, Harvard, Vancouver, ISO, and other styles

4

Asghari, Afshin. "Environnement sédimentaire, stratigraphie séquentielle et paléogéographie du Paléozoique de succession pré-Khuff dans le sud de l'Iran (Zagros et le Golfe Persique)." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS058/document.

Full text

Abstract:

Au cours du Précambrien et du Paléozoïque, la zone Zagros faisait partie de la plate-forme Arabe. La succession Paléozoïque du Zagros s’étend du Cambrien au Permien. La zone d'étude se situe entre le Lurestan et le Fars au sud et le Golfe Persique. Au Paléozoïque, dans le secteur du Zagros, la série stratigraphique comprend quatre séquences de second ordre (ou cycles tectonostratigraphiques) séparées par d’importantes discordances. L’eustatisme est le principal facteur déterminant les changements d’espace d’accommodation, même si localement dans l'Ouest du Haut Zagros, le rôle de la tectonique régionale et des mouvements diapririques est important. Le premier cycle (Ordovicien) est composé des Fomrations Seyahou (Floien-Katien) et Dargaz (Hirnantien). Il enregistre une évolution depuis des milieux profonds à peu profonds de plate-forme siliciclastique. La Formation Seyahou est découpée en sept séquences de troisième ordre et la Formation Dargaz correspondant à des dépôts glaciogènes comprends deux séquences de troisième ordre. Le deuxième cycle (Silurien inférieur) correspond à la Formation Sarchahan. Il est caractérisé des environnements marins peu profonds à profonds comprenant des marnes riches en matière organique. Il est composé par deux séquences de dépôt de troisième ordre. Localement à Kuh e Gahkum, la base de cette Formation enregistre des dépôts peu profonds de transition continental-marin dont la présence est attribuée à la mise en place d’un diapir dans le secteur. Le troisième cycle (Dévonien) correspond à la Formation Zakeen. Les dépôts évoluent depuis des environnements continentaux à marins. La fin du Dévonien est marqué par des environnements marins carbonatés dans le sud de la région du Fars et dans le Golfe Persique. Il est divisé en trois séquence de troisième ordre. L’absence de la Formation Zakeen à Kuh e Surmeh et Kuh e Siah, et sa présence dans les régions voisines (Naura, West Agar, etc ...), suggèrent une activité diapirique, expliquant l’érosion locale des séries sédimentaires. Le dernier cycle de la succession pré-khuff dans la zone d'étude correspond à la Formation Faraghan du Permien inférieur. Il surmonte une discontinuité attribué au jeu de l'orogenèse Hercynienne et est déposé dans toute la région du Zagros et dans le Golfe Persique. La Formation Faraghan correspond à des environnements de plaine côtière à marins et est divisé en trois séquences de troisième ordre.La succession du Paléozoïque est marquée par plusieurs discordances majeures. Elles résultent de: (i) variations majeures du niveau marin en lien avec des variations glacioeustatiques comme pour le cas de la glaciation Hirnantien à la fin de l’Ordovicien et celle du Carbonifère; (ii) Un soulèvement du Moyen-Orient à la fin du Silurien associé aux mouvements épeirogéniques et à une baisse importante du niveau de la mer; et (iii) l'orogenèse Hercynienne allant de la fin du Dévonien à Carbonifère. Localement, les discordances peuvent aussi s’expliquer par le jeu de remontée diapirique induisant une érosion locale, comme c’est le cas dans les secteurs de Kuh e Surmeh et de Kuh e Gakhum pour des periodes de temps différentes
During the Precambrian and trough the Palaeozoic, the Zagros area was part of the Arabian platform (Beydon, 1993). The Palaeozoic succession of the Zagros extends from Cambrian to well-developed Permian deposits. The study area ranges from the Lurestan to Southern Fars onshore and to the Persian Gulf offshore wells. From Ordovician to Early Permian Palaeozoic succession of the Zagros area comprises four second-order tectonostratigraphic depositional cycles separated by major unconformities. Eustatic sea-level variation is the main controlling factor for accommodation space changes, whereas in West High Zagros and Kuh e Gahkum, the role of regional and salt tectonic activities may be also important. The first cycle (Ordovician) is composed of the Seyahou (Floian-Katian) and Dargaz (Hirnantian) Formations. They are characterized by deep- to shallow-water (offshore to shoreface) siliciclastic deposits. The Seyahou Formation contains seven 3rd-order depositional sequences. The glaciogenic Dargaz Formation consists of one 3rd- order sequence. The second cycle (Early Silurian) corresponds to the Sarchahan Formation is composed of two 3rd-order depositional sequences. They are characterized by deep-marine offshore to upper offshore environments. Locally in Kuh e Gahkum the base of the Formation presented continental fan delta deposits due to the salt tectonic activity.The third cycle (Devonian) corresponds to the Zakeen Formation and divided in three 3rd-order depositional sequences. It started with the deposition of continental to near-shore marine clastic deposits. In Late Devonian, it evolved to carbonate marine deposits in the south of Fars area and the Persian Gulf. The lack of Zakeen Formation in Kuh e Surmeh and Kuh e Siah, and is presence in neighboring areas (Naura, Aghar, etc…), suggests structural salt plug activities (Jahani, 2008). This megasequence is capped by a major unconformity related to the Hercynian orogeny.The last deepening-upward cycle of the Pre-khuff succession in the study area is the Early Permian Faraghan Formation. It capped the Hercynian orogeny and deposited throughout the Zagros area from Lurestan (west) to Bandar Abbas (East) areas as well as in Persian Gulf. The Faraghan Formation divided into three 3rd-order depositional sequences and deposited in coastal plain to shallow-marin near-shore environment. Basinward, in the deeper part (e.g. Kuh e Faraghan), they are replaced by marine upper offshore deposits. The Palaeozoic succession is marked by several major unconformities associated with hiatus. They resulted from: (i) major sea level drops at the end of the Ordovician related to the Hirnantian glaciation (Ghavidel Syooki et al., 2011) and of during the Carboniferous related to the southern Hemisphere glaciation (Golonka, 2000); (ii) An uplift of the Middle East area at the end of the Silurian associated with epeirogenic movements (Ala et al., 1980; Berberian and King, 1981; Al-Sharhan and Nairn, 1997) and a major sea level drop at the end of Silurian (Al-Husseini, 1991,1992; Sharland et al., 2001; Konert et al., 2001; Haq and Al-Qahtani, 2005); and (iii) impact of the Hercynian orogeny spanning from the Late Devonian up to the Carboniferous (Al-Hosseini, 1992; Sharland et al., 2001; Konert et al., 2001, Faqira et al., 2009)

APA, Harvard, Vancouver, ISO, and other styles

5

Bessenay-Prolonge, Julie. "Au carrefour du plateau iranien et des steppes d'Asie Centrale : Tureng Tépé dans la plaine de Gorgan, des sociétés proto-urbaines aux forteresses de l'âge du Fer : étude strarigraphiques et architecturales menées d'après les archives inédites de la Mission Française à Tureng Tépé." Thesis, Paris 1, 2018. http://www.theses.fr/2018PA01H004.

Full text

Abstract:

Située dans le nord-est de l'Iran, au carrefour du plateau iranien et des steppes d'Asie Centrale, la plaine de Gorgân constitue, de par ses paysages et son climat, une région particulièrement favorable à l'installation humaine. Le site de Tureng Tépé, fouillé dans les années 1960-1970 par une équipe d'archéologues français, a livré une séquence d'occupation de plusieurs millénaires, depuis le chalcolithique jusqu'à l'époque moderne. L'étude stratigraphique et architecturale menée à partir des documents inédits issus des archives de fouille, a permis de reconstruire et de caractériser les occupations les plus anciennes du site, du Chalcolithique à l'Âge du Fer. Les niveaux archéologiques dégagés dans les secteurs du Petit Tépé et du Tépé Sud montrent ainsi une occupation continue depuis la fin du 4ème millénaire jusqu'au début du 2ème millénaire avant notre ère. L'Âge du Bronze Moyen est marqué par la construction d'une haute terrasse monumentales en briques dont une analyse architecturale approfondie a été réalisée. Par ailleurs, l'étude de plusieurs catégories d'artefacts montrent clairement l'existence de contacts et d'échanges longues distances entre d'une part les plaines de Gorgân et de Dâmghân, et d'autre part l'Asie Centrale méridionale, le Khorasan, et dans une moindre mesure les régions du sud-est du plateau iranien et du Baloutchistan. Après plusieurs siècles d'abandon, le site de Tureng Tépé est réoccupé à la fin de l'Âge du Fer II. Ces occupations, qui se distinguent clairement de celles de l'Âge du Bronze, sont représentés par une succession de fortifications reconstruites à plusieurs reprises
Located in the northeast of Iran, at the crossroads of the Iranian plateau and the steppes of Central Asia, the Gorgân plain is, by the nature of its landscapes and climate, a particularly suitable region for human settlements. The site of Tureng Tépé, excavated in the years 1960-1970 by a team of French archaeologists, revealed an occupational sequence of several millennia since Chalcolithic until the modem time. The stratigraphic and architectural study conducted from unpublished documents from the excavation archives, permit us to reconstruct and characterize the oldest occupations of the site, from Chalcolithic to the Iron Age. The archaeological layers discovered in the areas of the Petit Tépé and the Tépé Sud demonstrate continuous occupation from the end of the 4th millennium to the beginning of the 2nd millennium BC. The Middle Bronze Age is marked by the construction of a large monumental brick terrace of which an in-depth architectural analysis has been carried out. In addition, the study of several categories of artifacts clearly shows the existence of long-distance contacts and exchanges between on the one band the plains of Gorgan and Damghan, and on the other hand South Central Asia and Khorasan and to a lesser extent the southeastem regions of the Iranian plateau and Baluchistan. After several centuries of abandonment, Tureng Tépé is reoccupied at the end of the Iron Age II. These occupations, which are clearly distinguishable from those of the Bronze Age, are represented by a succession of fortifications rebuilt several times

APA, Harvard, Vancouver, ISO, and other styles

6

Dastanpour, Mohammad. "The Devonian stratigraphy of Kerman, southeast central Iran." Thesis, University of Bristol, 1990. http://hdl.handle.net/1983/5af05e94-ca3e-4e6e-ab46-e6dad2dde86d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Pufahl, Peir Kenneth. "Stratigraphic architecture of a paleoproterozoic iron formation depositional system, the Gunflint, Mesabi and Cuyuna iron ranges." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/MQ33432.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Gapara, Cornwell Sine. "A review of the deposition of iron-formation and genesis of the related iron ore deposits as a guide to exploration for Precambrian iron ore deposits in southern Africa." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005610.

Full text

Abstract:

Iron-formations are ferruginous sedimentary rocks which have their source from fumarolic activity associated with submarine volcanism, with deposition of iron as oxides, hydroxides, and hydrous oxide-silicate minerals in shallow and/or deep marine sedimentary systems. The Precambrian ironformations of southern Africa have a wide age range, but are more prominently developed before 1.SGa. These iron formations occur in greenstone belts of the Kaapvaal and Zimbabwean cratons, in the Limpopo mobile belt, in cratonic basins and in the Damara mobile belt. The Archaean-Proterozoic sedimentary basins and greenstone belts host iron ore deposits in iron-formation. Iron formations have a lengthy geological history. Most were subjected to intense, and on occasions repeated, tectonic and metamorphic episodes which also included metasomatic processes at times to produce supergene/hypogene high grade iron ores. Iron-formations may be enriched by diagenetic, and metamorphic processes to produce concentrating-grade ironformations. Uplift, weathering and denudation, have influenced the mineral association and composition of the ores, within which magnetite, haematite and goethite constitute the major ore minerals. The iron resources of the southern Africa region include the Sishen deposits, hosting to about 1200 Mt of high grade direct shipping ore, at >63% Fe. Deposits of Zimbabwe have more than 33 000 Mt of beneficiable iron-formation. The evaluation of an iron ore prospect involves many factors which must be individually assessed in order to arrive at an estimate of the probable profitability of the deposit. Many of these are geological and are inherent in the deposit itself. Other factors are inherent aspects of the environment in which the ore is formed. Although the geological character of the ore does not change, technological advances in the processing techniques may have a great effect on the cost of putting the ore into marketable form. Geochemical, geophysical and remote sensing methods would be used for regional exploration. Chip sampling and drilling are useful for detailed exploration. Purely geological exploration techniques are applicable on a prospect scale in the exploration of iron ore deposits. Regional exploration targeting should choose late Archaean greenstone belts containing oxide facies iron-formation or Early Proterozoic basins located at craton margins as they are both known to host high-grade haematite orebodies formed by supergene/hypogene enrichment. Most types of iron ore deposits in southern Africa are described and classified. An attempt is made to emphasize the major controls on mineralisation, in the hope that these may be applicable to exploration both in the southern African region and within analogous settings around the world.

APA, Harvard, Vancouver, ISO, and other styles

9

Muller, Katherine Charlotte. "Formation of iron-rimmed sandstone nodules on earth; terrestrial analogue for the formation of Martian blueberries?" Diss., Rolla, Mo. : Missouri University of Science and Technology, 2009. http://scholarsmine.mst.edu/thesis/pdf/Muller_2009_09007dcc8071b44c.pdf.

Full text

Abstract:

Thesis (M.S.)--Missouri University of Science and Technology, 2009.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 11, 2009) Includes bibliographical references (p. 85-87).

APA, Harvard, Vancouver, ISO, and other styles

10

Wightman, Gregory John. "Studies in the stratigraphy and chronology of iron age II-III in Palestine." Thesis, The University of Sydney, 1985. https://hdl.handle.net/2123/26034.

Full text

Abstract:

Research for this dissertation was undertaken in the Department of Archaeology at Sydney University during the years 1983-85, under the supervision of Professor J.B. Hennessy, whom I would like to thank for his encouragement and open-minded attitude.

APA, Harvard, Vancouver, ISO, and other styles

11

Müller, Stefan G. "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 Australia /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2006.0043.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Baldwin, Geoffrey James. "THE STRATIGRAPHY AND GEOCHEMISTRY OF THE RAPITAN IRON FORMATION, NORTHWEST TERRITORIES AND YUKON, CANADA." Thesis, Laurentian University of Sudbury, 2014. https://zone.biblio.laurentian.ca/dspace/handle/10219/2194.

Full text

Abstract:

The Neoproterozoic was a time of major change in Earth’s surficial history, including a major rise in atmospheric oxygen, the first appearance of complex metazoan life, and a series of worldwide glaciations. A particular interesting element of these so called “snowball Earth” glacial deposits is the presence of iron formation, a distinctive Precambrian rock type that is largely absent from the post-Paleoproterozoic record. Despite being relatively poorly studied with respect to their geochemistry and sedimentology, Neoproterozoic iron formations are used to support many models for the record of oxygen concentrations of the Earth. The classical example of Neoproterozoic iron formation is the Rapitan iron formation of northwestern Canada. This hematite-jasper iron formation is associated with glaciogenic turbidites and diamictites. Despite being the archetype, the Rapitan iron formation has not been studied in the context of recent ideas about the Neoproterozoic. In this thesis, the stratigraphy, geochemistry, and basin architecture of the Rapitan iron formation are reassessed. Using the REE+Y and the redox-sensitive elements Mo and U, it is shown that the Rapitan iron formation was deposited in a partially restricted basin from biogenically reduced iron under variable redox conditions. Elemental Re and Mo isotopes further show that although oxic and ferruginous conditions predominated during deposition of the iron formation, a transition towards a sulfidic water column locally terminated deposition. Finally, regional stratigraphy and geochemistry show that the iron formation was preferentially deposited in deep, newly formed basins that were protected from significant siliciclastic sedimentation. These basins were delimited by inferred crustal-scale faults trending roughly perpendicular to the axis of the rift basin, and allowed significant changes in thickness and sedimentological character over short distances along strike. These factors help build an overall geotectonic regime under which Neoproterozoic iron formations were deposited: young, deep rift basins that had undergone marine incursion, and were intermittently sealed by an ice shelf, allowing for the generation of an anoxic, iron-rich water column. The absence of the Eu anomaly and the heavy Mo isotopic signature indicate that the open ocean was fully oxygenated at the time of Rapitan iron formation deposition, as opposed to ferruginous as previously suggested.

APA, Harvard, Vancouver, ISO, and other styles

13

Zebari, Bahroz Gh A. "Controls on the spatial and temporal evolution and distribution of depositional components in the Paleocene-Lower Eocene Succession, Kurdistan Region-Iraq." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239281.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Pang, Kwan-Nang. "Origin of the permian panzhihua layered gabbroic intrusion and the hosted Fe-Ti-V oxide deposit, Sichuan Province, SW China." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B39634000.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Delvigne, Camille. "The Archaean silicon cycle insights from silicon isotopes and Ge/Si ratios in banded iron formations, palaeosols and shales." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209652.

Full text

Abstract:

The external silicon cycle during the Precambrian (4.5-0.5 Ga) is not well understood despite its key significance to apprehend ancient dynamics at the surface of the Earth. In the absence of silicifying organisms, external silicon cycle dramatically differs from nowadays. Our current understanding of Precambrian oceans is limited to the assumption that silicon concentrations were close to saturation of amorphous silica. This thesis aims to bring new insights to different processes that controlled the geochemical silicon cycle during the Archaean (3.8-2.5 Ga). Bulk rock Ge/Si ratio and Si isotopes (δ30Si) offer ideal tracers to unravel different processes that control the Si cycle given their sensitivity to fractionation under near-surface conditions.

First, this study focuses on Si inputs and outputs to ocean over a limited time period (~2.95 Ga Pongola Supergroup, South Africa) through the study of a palaeosol sequence and a contemporaneous banded iron formation. The palaeosol study offers precious clues in the comprehension of Archaean weathering processes and Si transfer from continent to ocean. Desilication and iron leaching were shown to be the major Archaean weathering processes. The occurrence of weathering residues issued of these processes as major component in fine-grained detrital sedimentary mass (shales) attests that identified weathering processes are widely developed and suggest an important dissolved Si flux from continent to the ocean. In parallel, banded iron formations (BIFs), typically characterised by alternation of iron-rich and silica-rich layers, represent an extraordinary record of the ocean-derived silica precipitation throughout the Precambrian. A detailed study of a 2.95 Ga BIF with excellent stratigraphic constraints identifies a seawater reservoir mixed with significant freshwater and very limited amount of high temperature hydrothermal fluids as the parental water mass from which BIFs precipitated. In addition, the export of silicon promoted by the silicon adsorption onto Fe-oxyhydroxides is evidenced. Then, both Si- and Fe-rich layers of BIFs have a common source water mass and a common siliceous ferric oxyhydroxides precursor. Thus, both palaeosols and BIFs highlight the significance of continental inputs to ocean, generally under- estimated or neglected, as well as the close link between Fe and Si cycles.

In a second time, this study explores secular changes in the Si cycle along the Precambrian. During this timespan, the world ocean underwent a progressive decrease in hydrothermal inputs and a long-term cooling. Effects of declining temperature over the oceanic Si cycle are highlighted by increasing δ30Si signatures of both chemically precipitated chert and BIF through time within the 3.8-2.5 Ga time interval. Interestingly, Si isotope compositions of BIF are shown to be kept systematically lighter of about 1.5‰ than contemporaneous cherts suggesting that both depositions occurred through different mechanisms. Along with the progressive increase of δ30Si signature, a decrease in Ge/Si ratios is attributed to a decrease in hydrothermal inputs along with the development of large and widespread desilication during continental weathering.

Le cycle externe du silicium au précambrien (4.5-0.5 Ga) reste mal compris malgré sa position clé dans la compréhension des processus opérant à la surface de la Terre primitive. En l’absence d’organismes sécrétant un squelette externe en silice, le cycle précambrien du silicium était vraisemblablement très différent de celui que nous connaissons à l’heure actuelle. Notre conception de l’océan archéen est limitée à l’hypothèse d’une concentration en silicium proche de la saturation en silice amorphe. Cette thèse vise à une meilleure compréhension des processus qui contrôlaient le cycle géochimique externe du silicium à l’archéen (3.8-2.5 Ga). Dans cette optique, le rapport germanium/silicium (Ge/Si) et les isotopes stables du silicium (δ30Si) représentent des traceurs idéaux pour démêler les différents processus contrôlant le cycle du Si.

Dans un premier temps, cette étude se focalise sur les apports et les exports de silicium à l’océan sur une période de temps restreinte (~2.95 Ga Pongola Supergroup, Afrique du Sud) via l’étude d’un paléosol et d’un dépôt sédimentaire de précipitation chimique quasi-contemporain. L’étude du paléosol apporte de précieux indices quant aux processus d’altération archéens et aux transferts de silicium des continents vers l’océan. Ainsi, la désilicification et le lessivage du fer apparaissent comme des processus majeurs de l’altération archéenne. La présence de résidus issus de ces processus d’altération en tant que composants majeurs de dépôts détritiques (shales) atteste de la globalité de ces processus et suggère des flux significatifs en silicium dissout des continents vers l’océan. En parallèle, les « banded iron formations » (BIFs), caractérisés par une alternance de niveaux riches en fer et en silice, représentent un enregistrement extraordinaire et caractéristique du précambrien de précipitation de silice à partir de l’océan. Une étude détaillée d’un dépôt de BIFs permet d’identifier une contribution importante des eaux douces dans la masse d’eau à partir de laquelle ces roches sont précipitées. Par ailleurs, un mécanisme d’export de silicium via absorption sur des oxyhydroxydes de fer est mis en évidence. Ainsi, les niveaux riches en fer et riche en silice constituant les BIFs auraient une même origine, un réservoir d’eau de mer mélangée avec des eaux douces et une contribution minime de fluides hydrothermaux de haute température, et un même précurseur commun. Dès lors, tant les paléosols que les BIFs mettent en évidence l’importance des apports continentaux à l’océan, souvent négligés ou sous estimés, ainsi que le lien étroit entre les cycles du fer et du silicium.

Dans un second temps, cette étude explore l’évolution du cycle du silicium au cours du précambrien. Durant cette période, l’océan voit les apports hydrothermaux ainsi que sa température diminuer. Dans l’intervalle de temps 3.8-2.5 Ga, les effets de tels changements sur le cycle du silicium sont marqués par un alourdissement progressif des signatures isotopiques des cherts et des BIFs. Le fort parallélisme entre l’évolution temporelle des compositions isotopiques des deux précipités met en évidence leur origine commune, l’océan. Cependant, les compositions isotopiques des BIFs sont systématiquement plus légères d’environ 1.5‰ que les signatures enregistrées pas les cherts. Cette différence est interprétée comme le reflet de mécanismes de dépôts différents. L’alourdissement progressif des compositions isotopiques concomitant à une diminution des rapports Ge/Si reflètent une diminution des apports hydrothermaux ainsi que la mise en place d’une désilicification de plus en plus importante et/ou généralisée lors de l’altération des continents.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

APA, Harvard, Vancouver, ISO, and other styles

16

Hayes, Dawn Schmidli. "Stratigraphic, Microfossil, and Geochemical Analysis of the Neoproterozoic Uinta Mountain Group, Utah: Evidence fo a Eutrophication Event?" DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/874.

Full text

Abstract:

Several previous Neoproterozoic microfossil diversity studies yield evidence for arelatively sudden biotic change prior to the first well‐constrained Sturtian glaciations. In an event interpreted as a mass extinction of eukaryotic phytoplankton followed by bacterial dominance, diverse assemblages of complex acritarchs are replaced by more uniform assemblages consisting of simple leiosphaerid acritarchs and bacteria. Recent data from the Chuar Group of the Grand Canyon (770‐742 Ma) suggest this biotic change was caused by eutrophication rather than the direct effects of Sturtian glaciation; evidence includes total organic carbon increases indicative of increasing primary productivity followed by iron speciation values that suggest sustained water column anoxia. A new data set (this study) suggests that this same eutrophication event may be recorded in shale units of the formation of Hades Pass and the Red Pine Shale of Utah’s Neoproterozoic Uinta Mountain Group (770‐742 Ma). Results of this study include a significant shift from a higher‐diversity (H’= 0.60) fauna that includes some ornamented acritarchs to a lower‐diversity (H’ = 0.11) fauna dominated by smooth leiosphaerids and microfossils of a bacterial origin (Bavlinella/ Sphaerocongregus sp.). This biotic change co‐occurs with a significant increase in total iii organic carbon values that directly follows a positive carbon‐isotopic excursion, suggesting increased primary productivity that may have been the result of elevated sediment influx and nutrient availability. Both the biotic change and period of increased total organic carbon values correspond with the onset of an interval of anoxia (indicated by total iron to aluminum ratios above 0.60) and a spike in sulfur concentration. Like those reported from the Chuar Group, these biotic and geochemical changes in the upper Uinta Mountain Group are independent of changes in lithofacies , and they suggest that either a eutrophication event or direct inhibition of eukaryotes by sulfide (or perhaps both) may have been the cause of the biotic turnover. These findings support current correlations between the Uinta Mountain and Chuar Groups, the idea that the biotic turnover preserved in both strata was at least a regional phenomenon, and current models of punctuated global ocean anoxia during mid‐ to late‐Neoproterozoic time. Whether or not this hypothesized eutrophication event was more than regional in extent remains a very interesting question and will certainly be a focus of future research.

APA, Harvard, Vancouver, ISO, and other styles

17

Muller, Stefan G. "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 Australia." University of Western Australia. School of Earth and Geographical Sciences, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0043.

Full text

Abstract:

[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.

APA, Harvard, Vancouver, ISO, and other styles

18

Zhao, Xinfu. "Paleoproterozoic crustal evolution and Fe-Cu metallogeny of the western Yangtze Block, SW China." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B43572261.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Sedlacek, Alexa R. C. "Strontium isotope stratigraphy and carbonate sedimentology of the latest Permian to Early Triassic in the western United States, northern Iran and southern China." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1372971425.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

MacQueen, John Kenneth Carleton University Dissertation Geology. "Stratigraphy, structure and gold mineralization of the No. 5 vein/iron formation zone, Pickle Crow Gold Mines, Pickle Lake, Ontario." Ottawa, 1987.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

21

Alonazi, Majed Turki F. "A re-evaluation of stratigraphic and ceramic evidence from the Bronze and Iron Age site of al-Ṣināʿiyyah at Tayma in Saudi Arabia." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12809/.

Full text

Abstract:

This work investigated the ceramics from Ṣināʿiyyah site in Tayma Area. In particular, this study aimed to determine their types, source and chronology. Also, it aimed to find out their distribution within and outside Tayma Area, in order to increase our knowledge of the history of Tayma and its contacts. Hausleiter (2014) has classified Tayma ceramics into a number of groups, of which four of groups are attested in Ṣināʿiyyah assemblage. The features and the suggested dates for these ceramics were reviewed below. Moreover, several excavations have been conducted at Ṣināʿiyyah, and a large number of ceramics were derived from these excavations. However, the ceramics in the published reports are very few, and very important information related to these ceramics is not avialable. Therefore, new excavations in Ṣināʿiyyah were expected to provide significant results regarding the sequences and the dating of these ceramics. For these reasons, as the main part of the current study, two new excavations were conducted in Ṣināʿiyyah site. The ceramics derived from these excavations were divided into six groups based on their physical attributes. These groups were made up of three types of fabric which, according to previous petrographic studies, are related to the geology of Tayma, and may therefore have been made there. Ceramics parallel to the Ṣināʿiyyah groups were also attested in several sites in Tayma, north-west of Arabia and southern Levant. Based on integrating the stratigraphic evidence and C14 dates from our excavations at Ṣināʿiyyah, together with the evidence from the other sites where these groups were found, the six groups from Ṣināʿiyyah were dated (in general) between the early 2 nd millennium BC to the 10 th -5 th century BC. According to the suggested dating and distribution for each group of ceramics, the contact between Tayma and Qurayyah is suggested to have started from the early 2 nd millennium BC and endured more than ten centuries. Whereas, there is evidence which indicates that Tayma was in direct contacts with south Levant and Egypt during the Early Iron Age.

APA, Harvard, Vancouver, ISO, and other styles

22

Polteau, Stéphane. "The early proterozoic Makganyene glacial event in South Africa : its implication in sequence stratigraphy interpretations, paleoenvironmental conditions and iron and manganese ore deposition." Thesis, Rhodes University, 2005. http://hdl.handle.net/10962/d1007612.

Full text

Abstract:

The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.

APA, Harvard, Vancouver, ISO, and other styles

23

Stone, Michelle Susanne. "Depositional history and mineralisation of tertiary channel iron deposits at Yandi, Eastern Pilbara, Australia." University of Western Australia. School of Earth and Geographical Sciences, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0082.

Full text

Abstract:

[Truncated abstract] Detailed sedimentological, petrographical, geochemical and palynological studies have provided insight into the source rocks and the processes that operated during formation of the Tertiary Yandi channel iron deposit (CID) of the eastern Pilbara, Western Australia. Yandi is the largest and most valuable CID in the world, accounting for more than 2.5% of global iron production in 2003, and is the type-example of CID. The Yandi CID occupies the palaeo-Marillana Creek in the central Hamersley Ranges. It is near-coincident-with the modern Marillana Creek which incised Proterozoic bedrock of the Weeli Wolli Formation (Hamersley Group) and associated dolerite intrusions. Three lithostratigraphic units fill the palaeo-Marillana Creek and comprise the Marillana Formation. The units in stratigraphic order are the: (1) Munjina Member; (2) Barimunya Member, which hosts the majority of the iron resource; and (3) Iowa Eastern Member. Fossil pollen and spores in organic-rich claystones in the Munjina Member indicate that deposition of the Marillana Formation most likely commenced in the Early Oligocene in response to erratic seasonal flows with high energy flood events and intervening quiescent suspension settling of clays. The Marillana Formation consists of twelve facies. These conglomerate and clay facies form three facies associations. The basal facies association is composed of polymictic conglomerate, clay and interbedded CID that represents a lag deposit along the base of the palaeochannel. This facies association characterises the Munjina Member. The second facies association consists of iron-rich conglomerate sheets, bars and subordinate scour-fills and characterises the Barimunya Member. Channel iron deposits of the overlying Iowa Eastern member consist of reworked Barimunya Member iron conglomerates. The upper facies association is polymictic conglomerate with clay that characterises the remainder of the Iowa Eastern Member. Polymictic iron conglomerate in the Munjina and Barimunya Members contains Weeli Wolli Formation and dolerite clasts indicating local derivation. Rare earth element profiles of the other iron conglomerate facies indicate derivation of the Barimunya and Iowa Eastern CID from a different source. These iron conglomerates are characterised by relatively flat LREE profiles. The LREE exhibit an enriched profile approaching the MREE [(average La/Nd)N = 0.7], and the HREE profile shows minor enrichment approaching ytterbium [(average Dy/Yb)N = 0.9]. Comparison of iron conglomerate REE profiles to those of the bedrock indicates that these conglomerates were most probably derived from the Joffre Formation BIF of the Hamersley Group

APA, Harvard, Vancouver, ISO, and other styles

24

Verdel, Charles Steven Eiler John Eiler John. "I. Cenozoic geology of Iran : an integrated study of extensional tectonics and related volcanism. II. Ediacaran stratigraphy of the North American cordillera : new observations from eastern California and northern Utah /." Diss., Pasadena, Calif. : California Institute of Technology, 2009. http://resolver.caltech.edu/CaltechETD:etd-09182008-092505.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Greentree, Matthew Richard. "Tectonostratigraphic analysis of the Proterozoic Kangdian iron oxide - copper province, South-West China." University of Western Australia. Tectonics Special Research Centre, 2007. http://theses.library.uwa.edu.au/adt-WU2009.0054.

Full text

Abstract:

The Cenozoic Ailaoshan Red River shear zone marks the present day western margin of the South China Block. Along this margin are well preserved late Paleoproterozoic to early Neoproterozoic sedimentary and volcanic successions. This work examines the ages and tectonic environments for the formation of the successions, as well as significance of the regional tectono-magmatic events on the formation of widespread iron oxide-copper deposits. The oldest succession is the Paleoproterozoic Dahongshan Group. A new SHRIMP UPb age of 1675 ± 8 Ma for a tuffaceous schist unit confirms its Paleoproterozoic age. Detrital zircon ages of the Dahongshan Group range between Archean to Paleoproterozoic (ca. 2780 1860 Ma). They include a population of ca. 2400 2100 Ma grains, which have no known source region on the exposed Yangtze Block. Previous geochemical studies of metavolcanic rocks from the Dahongshan Group have suggested that these rocks were erupted in an oceanic setting. However, this study shows that the metavolcanics are extremely altered and cannot be used for reliable tectonic discrimination. Based on the characteristics of sedimentary rocks in the Dahongshan Group, it is suggested that these rocks were deposited in a continental setting. Overlying the Dahongshan Group is a thick sedimentary sequence which has been variably termed the Kunyang, Dongchuan, Huili or Xide Groups. In the past, these rocks have been considered as a Mesoproterozoic rift succession. However, no precise age constraints were available for the succession. In this study, this sequence is found to contain at least two separate tectonostratigraphic units. The oldest (ca.1140 Ma) is comprised of alkaline basalt with a geochemical and isotopic character similar to that of modern intracontinental rift basalts. The presence of Cathaysia-derived sediments in this unit indicates sedimentary transportation from the southerly Cathaysia Block to the northerly Yangtze Block (in present coordinates) in South China at that time, which suggests an impactogen scenario. The thick sedimentary sequence of what has traditionally been defined as the Kunyang Group has been found to have significantly younger depositional age of ca.1000 960 Ma. The composition of sedimentary rocks and the provenance of detrital zircons from the Kunyang Group are consistent with a foreland basin setting. The depositional age of this sequence coincides with the timing of Sibao Orogeny as determined elsewhere in the South China Block. Summary Page ii Numerous iron oxide - copper (gold) deposits occur within the rocks of the Dahongshan and Kunyang Groups. Previous studies have classified these deposits into two deposit styles: the Dahongshan-type Paleoproterozoic VMS mineralisation hosted within the Dahongshan Group, and the Dongchuan-type diagenetic carbonate and shale-hosted deposits hosted within the Kunyang Group. However, both deposit types share similarities with the iron oxide copper (gold) deposit class, such as stratabound disseminated and massive copper ores, abundance of iron oxide occurring mostly as low Ti - magnetite and haematite, and variable enrichments in Au, Ag, Co, F, Mo, P and REE. 40Ar/39Ar data from both deposit types indicate mineralisation ages of ca. 850 830 Ma and 780 740 Ma.

APA, Harvard, Vancouver, ISO, and other styles

26

彭君能 and Kwan-Nang Pang. "Origin of the permian panzhihua layered gabbroic intrusion and the hosted Fe-Ti-V oxide deposit, Sichuan Province, SW China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B39634000.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Land, Jarred. "Genesis of BIF-hosted hematite iron ore deposits in the central part of the Maremane anticline, Northern Cape Province, South Africa." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1020905.

Full text

Abstract:

The Paleoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa is host to high-grade BIF-hosted hematite iron-ore deposits and is the country’s most important source of iron to date. Previous work has failed to provide a robust and all-inclusive genetic model for such deposits in the Transvaal Supergroup; in particular, the role of hydrothermal processes in ore-genesis has not been adequately clarified. Recent studies by the author have produced evidence for hydrothermal alteration in shales (Olifantshoek Supergroup) stratigraphically overlying the iron-ore intervals; this has highlighted the need to reassess current ore-forming models which place residual supergene processes at the core of oregenesis. This thesis focuses on providing new insights into the processes responsible for the genesis of hematite iron ores in the Maremane anticline through the use of newly available exploration drill-core material from the centre of the anticline. The study involved standard mineralogical investigations using transmitted/reflected light microscopy as well as instrumental techniques (XRD, EPMA); and the employment of traditional whole-rock geochemical analysis on samples collected from two boreholes drilled in the centre of the Maremane anticline, Northern Cape Province. Rare earth element analysis (via ICP-MS) and oxygen isotope data from hematite separates complement the whole-rock data. Iron-ore mineralisation examined in this thesis is typified by the dominance of Fe-oxide (as hematite), which reaches whole-rock abundances of up to 98 wt. % Fe₂O₃. Textural and whole-rock geochemical variations in the ores likely reflect a variable protolith, from BIF to Fe-bearing shale. A standard supergene model invoking immobility and residual enrichment of iron is called into question on the basis of the relative degrees of enrichment recorded in the ores with respect to other, traditionally immobile elements during chemical weathering, such as Al₂O₃ and TiO₂. Furthermore, the apparently conservative behaviour of REE in the Fe ore (i.e. low-grade and high-grade iron ore) further emphasises the variable protolith theory. Hydrothermally-induced ferruginisation is suggested to post-date the deposition of the post-Transvaal Olifantshoek shales, and is likely to be linked to a sub-surface transgressive hydrothermal event which indiscriminately transforms both shale and BIF into Fe-ore. A revised, hydrothermal model for the formation of BIF-hosted high-grade hematite iron ore deposits in the central part of the Maremane anticline is proposed, and some ideas of the author for further follow-up research are presented.

APA, Harvard, Vancouver, ISO, and other styles

28

Rafuza, Sipesihle. "Carbonate petrography and geochemistry of BIF of the Transvaal supergroup : evaluating the potential of iron carbonates as proxies for palaeoproterozoic ocean chemistry." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018611.

Full text

Abstract:

The subject of BIF genesis, particularly their environmental conditions and ocean chemistry at the time of deposition and their evolution through time, has been a subject of much contentiousness, generating a wealth of proposed genetic models and constant refinements thereof over the years. The prevailing paradigm within the various schools of thought, is the widespread and generally agreed upon depositional and diagenetic model(s) which advocate for BIF deposition under anoxic marine conditions. According to the prevailing models, the primary depositional environment would have involved a seawater column whereby soluble Fe²⁺ expelled by hydrothermal activity mixed with free O₂ from the shallow photic zone produced by eukaryotes, forming a high valence iron oxy-hydroxide precursor such as FeOOH or Fe(OH)₃. An alternative biological mechanism producing similar ferric precursors would have been in the form of photo-ferrotrophy, whereby oxidation of ferrous iron to the ferric form took place in the absence of biological O₂ production. Irrespective of the exact mode of primary iron precipitation (which remains contentious to date), the precipitated ferric oxy-hydroxide precursor would have reacted with co-precipitated organic matter, thus acting as a suitable electron acceptor for organic carbon remineralisation through Dissimilatory Iron Reduction (DIR), as also observed in many modern anoxic diagenetic environments. DIR-dominated diagenetic models imply a predominantly diagenetic influence in BIF mineralogy and genesis, and use as key evidence the low δ¹³C values relative to the seawater bicarbonate value of ~0 ‰, which is also thought to have been the dissolved bicarbonate isotope composition in the early Precambrian oceans. The carbon for diagenetic carbonate formation would thus have been sourced through a combination of two end-member sources: pore-fluid bicarbonate at ~0 ‰ and particulate organic carbon at circa -28 ‰, resulting in the intermediate δ¹³C values observed in BIFs today. This study targets 65 drillcore samples of the upper Kuruman and Griquatown BIF from the lower Transvaal Supergroup in the Hotazel area, Northern Cape, South Africa, and sets out to explore key aspects in BIF carbonate petrography and geochemistry that are pertinent to current debates surrounding their interpretation with regard to primary versus diagenetic processes. The focus here rests on applications of carbonate (mainly siderite and ankerite) petrography, mineral chemistry, bulk and mineral-specific carbon isotopes and speciation analyses, with a view to obtaining valuable new insights into BIF carbonates as potential records of ocean chemistry for their bulk carbonate-carbon isotope signature. Evaluation of the present results is done in light of pre-existing, widely accepted diagenetic models against a proposed water-column model for the origin of the carbonate species in BIF. The latter utilises a combination of geochemical attributes of the studied carbonates, including the conspicuous Mn enrichment and stratigraphic variability in Mn/Fe ratio of the Griquatown BIF recorded solely in the carbonate fraction of the rocks. Additionally, the carbon isotope signatures of the Griquatown BIF samples are brought into the discussion and provide insights into the potential causes and mechanisms that may have controlled these signatures in a diagenetic versus primary sedimentary environment. Ultimately, implications of the combined observations, findings and arguments presented in this thesis are presented and discussed with particular respect to the redox evolution and carbon cycle of the ocean system prior to the Great Oxidation Event (GOE). A crucial conclusion reached is that, by contrast to previously-proposed models, diagenesis cannot singularly be the major contributing factor in BIF genesis at least with respect to the carbonate fraction in BIF, as it does not readily explain the carbon isotope and mineral-chemical signatures of carbonates in the Griquatown and uppermost Kuruman BIFs. It is proposed instead that these signatures may well record water-column processes of carbon, manganese and iron cycling, and that carbonate formation in the water column and its subsequent transfer to the precursor BIF sediment constitutes a faithful record of such processes. Corollary to that interpretation is the suggestion that the evidently increasing Mn abundance in the carbonate fraction of the Griquatown BIF up-section would point to a chemically evolving depositional basin with time, from being mainly ferruginous as expressed by Mn-poor BIFs in the lower stratigraphic sections (i.e. Kuruman BF) to more manganiferous as recorded in the upper Griquatown BIF, culminating in the deposition of the abnormally enriched in Mn Hotazel BIF at the stratigraphic top of the Transvaal Supergroup. The Paleoproterozoic ocean must therefore have been characterised by long-term active cycling of organic carbon in the water column in the form of an ancient biological pump, albeit with Fe(III) and subsequently Mn(III,IV) oxy-hydroxides being the key electron acceptors within the water column. The highly reproducible stratigraphic isotope profiles for bulk δ¹³C from similar sections further afield over distances up to 20 km, further corroborate unabatedly that bulk carbonate carbon isotope signatures record water column carbon cycling processes rather than widely-proposed anaerobic diagenetic processes.

APA, Harvard, Vancouver, ISO, and other styles

29

Zaina, Federico. "Stratigraphy, chronology and architecture of the earliest phases at kish in Central Mesopotamia : from the Jemdet Nasr to the Ur III period (3100-2000 BC)." Thesis, Paris 1, 2015. http://www.theses.fr/2015PA010706.

Full text

Abstract:

La ville de Kiš a été l’un des centres les plus importants dans le cadre sociopolitique de la Mésopotamie entre le 4ème et le 1er milliéraine av. J.C. Les fouilles effectuées entre 1923 et 193 par l’expédition de l’Université d’Oxford et le Field Museum de Chicago ont largement exploré le site, malgré les résultats significatifs obtenus, les insuffisantes méthodes de fouilles ont affecté négativement l’interprétation archéologique produite dans les publications. Le but de ce projet est de contribuer à combler ces lacunes dans les connaissances, en reconstruisant les phases archéologiques et historiques fouillée à Kiš en datant entre la période du Jemdet Nasr et celle de Ur III. Tout d’abord, pour comprendre l’urbanisme de Kiš entre le 4ème et la fin de la première moitié du 2ème milliéraine av. J.C., j’ai produit une reconstruction des contextes stratigraphiques et architecturaux découverts dans certains chantier de fouilles dans le site. Des nouvelles sections et des plans de chaque chantier de fouilles ainsi qu’une carte générale de Kiš ont été produit. Celles-ci ont été utilisées comme outils pour interpréter le développement de l’aménagement urbain et architectural de Kiš. A côté de l’analyse des vestiges structuraux, il a eu l’étude des matériaux stratifiés. Une sélection rigoureuse des objets conservés dans les dépôts et les musées universitaires, sera faite. En outre, une analyse technologique des échantillons sélectionnés, a été entreprise afin de fournir de plus amples informations à propos de chaque catégorie. Enfin, les matériaux ont été associés à leur contexte d’origine
The city of Kiš was one of the most important centersof Mesopotamia between the 4 th and 1st millenium BC The excavations carried out between 1923 and 1933 by the expedition from the University and the Field Museum of Chicago have largely explored the site, but despite significant results, the inadequate methods of excavation have negatively affected the archaeological interpretation produced in publications. The goal of this project is that of contributing to fill these gaps in knowledge, reconstructing archaelogical and historical phases searched to Kiš dating from the period Jemdet Nasr and the Ur III. The first aim was to understand the planning of Kiš between the 4th and the end of the first half of the 2nd millenium BC. To this aim I reconstructed the stratigraphic and architectural contexts discovered in some areas of the site. New sections and plans of each area and a general map of Kiš was produced. These were used as tools to interpret the development of urban and architectural development of Kiš. Beside the analysis of strcutural remains, there has been the study of layered materials. Careful selection of objects keps in deposits and university museums, will be made. In addition, radiocarbon analysis of selected samples was undertaken to provide more information on the site chronology. Finally, the materials were associated with their original context

APA, Harvard, Vancouver, ISO, and other styles

30

Zhao, Xinfu, and 赵新福. "Paleoproterozoic crustal evolution and Fe-Cu metallogeny of the western Yangtze Block, SW China." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B43572261.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Furlong, Pierce James. "Aspects of ancient Near Eastern chronology (c. 1600-700 BC)." Melbourne, 2007. http://repository.unimelb.edu.au/10187/2096.

Full text

Abstract:

The chronology of the Late Bronze and Early Iron Age Near East is currently a topic of intense scholarly debate. The conventional/orthodox chronology for this period has been assembled over the past one-two centuries using information from King-lists, royal annals and administrative documents, primarily those from the Great Kingdoms of Egypt, Assyria and Babylonia. This major enterprise has resulted in what can best be described as an extremely complex but little understood jigsaw puzzle composed of a multiplicity of loosely connected data. I argue in my thesis that this conventional chronology is fundamentally wrong, and that Egyptian New Kingdom (Memphite) dates should be lowered by 200 years to match historical actuality. This chronological adjustment is achieved in two stages: first, the removal of precisely 85 years of absolute Assyrian chronology from between the reigns of Shalmaneser II and Ashur-dan II; and second, the downward displacement of Egyptian Memphite dates relative to LBA Assyrian chronology by a further 115 years. Moreover, I rely upon Kuhnian epistemology to structure this alternate chronology so as to make it methodologically superior to the conventional chronology in terms of historical accuracy, precision, consistency and testability.

APA, Harvard, Vancouver, ISO, and other styles

32

Taheri, Jafar. "Stratigraphy, ichnology, and sedimentary environments of the Late Bajocian-Late Bathonian Kashafrud Formation, Northeastern Iran." Doctoral thesis, 2009. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-39966.

Full text

Abstract:

The Upper Bajocian-Bathonian Kashafrud Formation is a thick package of siliciclastic sediments that crops out in NE Iran from the southeast, near the Afghanistan border, to north- northwestern areas around the city of Mashhad. The thickness ranges from less than 300 m in a deltaic succession (Kuh-e-Radar) to more than 2500 m in the Maiamay area, but the normal thickness in Ghal-e-Sangi, Kol-e-Malekabad, and Fraizi areas is about 1200-1300 m. It is the fill of an elongated basin, which extended for more than 200 km in NW-SE direction and a width of at least 50 km along the southern margin of the Koppeh Dagh. Prior to this study, little information existed about the sedimentary environments and other characters, especially the geometry of the basin. Exact biostratigraphic data from the top of the Kashafrud Formation were rare. Based on the macrofauna from the lower part of the overlying Chamanbid Formation the upper boundary of the Kashafrud Formation had been attributed to the Late Bathonian and/or Early Callovian, but now the upper limit of the Kashafrud Formation is defined as Late Bathonian in age, based on ammonite biostratigraphy. Except for chapter one, which deals with the introduction and related sub-titles, in the following chapters, step by step, field observations and data were surveyed according to the questions to solve. In order to reconstruct the facies architecture and the geometry of the basin, a number of sections have been logged in detail (see chapter 3, “The sections”). The exact biostratigraphic setting is discussed in chapter 4 (“Biostratigraphy”). Sedimentary environments range from non-marine alluvial fans and braided rivers in the basal part of the succession to deltas, storm-dominated shelf, slope and deep-marine basin. The latter comprises the largest part of the basin fill, consisting of monotonous mudstones, siltstones and proximal to distal turbidities. The only continuous carbonate unit (~30 m) locally formed at Tappenader. Other localities in which thin fossil-bearing carbonate strata occur are Torbat-e-Jam (benthic fauna) and, to a lesser extent, Ghal-e-Sangi. These rare shallow-water carbonates, which also contain corals, represent only short intervals (see chapter 5,” Facies association and sedimentary environments”). Relative changes in sea level were reconstructed on the basis of deepening- and shallowing-upward trends. Sequence boundaries and parasequences have been distinguished and analyzed in chapter 6 (“Sequence stratigraphy”). In most areas, the basin rapidly evolved from a shallow marine, transgressive succession to a deep-marine, basinal succession. The only area where shallow conditions persisted from the Late Bajocian to the Late Bathonian, and even into the Early Callovian is the Kuh-e-Radar area which corresponds to a fan-delta setting. A trace fossil analysis has been carried out to obtain additional evidence on the bathymetry of the basin (see chapter 7, “Ichnology”). Altogether 29 ichnospecies belonging to 15 ichnogenera have been identified, as well as 10 ichnogenera, which were determined only at genus level. They can be grouped in the well-known “Seilacherian ichnofacies”. Very high subsidence rates and strong lateral thickness variations suggest that the Kashafrud Formation is a rift related basin that formed as the eastern extension of the South Caspian Basin. The basin evolution is reviewed, the eastern and western continuations of the basin were checked in the field and also in the literature (see chapter 8, “Basin evolution”). In all, the present study provided new insights into the development of the Kashafrud Formation, e.g. more biostratigraphic data from the base and the top of the succession, a relatively complete picture of the trace fossil associations, a better recognition and reconstruction of the sedimentary environments in different parts of the basin. Finally this research project will be a good basis for further investigations, especially towards the west, as parts of the Kashafrud Formation are source rocks of a hydrocarbon reservoir in NE Iran.

APA, Harvard, Vancouver, ISO, and other styles

33

Taheri, Jafar [Verfasser]. "Stratigraphy, ichnology, and sedimentary environments of the Late Bajocian, Late Bathonian Kashafrud Formation, Northeastern Iran / vorgelegt von Jafar Taheri." 2009. http://d-nb.info/998400831/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Pecoits, Ernesto. "Ediacaran iron formations and carbonates from Uruguay: palaeoceanographic, palaeoclimatic and palaeobiologic implications." Phd thesis, 2010. http://hdl.handle.net/10048/1296.

Full text

Abstract:

The Ediacaran in Uruguay preserves a unique record of deposits generated during the assembly of the palaeocontinent Gondwana and concurrent with major changes in the atmosphere and oceans, and the rise of animal life. Recent studies have suggested that the deep oceans remained anoxic and highly ferruginous throughout the Ediacaran and possibly into the Cambrian. Unfortunately, acceptance of this idea has been hindered by the virtual absence of iron formations (IF). Detailed studies of Ediacaran IF in Uruguay confirm that ferruginous conditions dominated the pre-Gaskiers (~580 Ma), and interestingly, they also extended well into the upper Ediacaran before complete ocean ventilation occurred. Significantly, a simple twolayer stratified system that argues for an oxygenated surface layer overlying a suboxic zone is proposed. The association of negative 13C excursions in Neoproterozoic carbonates and large-scale glaciations has become a tempting explanation for the short-term perturbation of the global carbon cycle. Not surprisingly, negative 13C shifts in Ediacaran-aged carbonates from Uruguay have been interpreted as recording post-Gaskiers glacial events. New highresolution 13C-chemostratigraphy of carbonates shows negative fractionations in deep facies with a progressive rise towards shallow-water settings, and suggests a deposition across a stratified ocean. Furthermore, 87Sr/86Sr chemostratigraphy coupled with radiometric data allowed a more precise chronostratigraphy, which supports an age of ~600-575 Ma for the unit, and suggests a deposition concurrent with the Gaskiers glaciation. Notwithstanding whether associated 13C variations in shallow water facies were produced by glacially-related conditions or by the dynamic of the basin itself remains unresolved. Although these conclusions are particularly valid for these deposits, they carry important implications for the understanding of other negative 13C excursions recorded in the Precambrian. Finally, bilaterian burrows occur in Gaskiers age glaciomarine rocks in Uruguay implying that these are the oldest definite animal tracks yet reported. Crucially, our new discovery unites the palaeontological and molecular data pertaining to the origin of bilaterians, and brings the origin of animals firmly into the interval of the Neoproterozoic glaciations. It also implies that ancestral bilaterians likely evolved first in relatively shallow seas, and only colonized the deep-sea floor once sufficient bottom water oxygenation had taken place.

APA, Harvard, Vancouver, ISO, and other styles

35

Quarles, van Ufford Andrew I. (Andrew Ian) 1967. "Stratigraphy, structural geology, and tectonics of a young forearc-continent collision, western Central Range, Irian Jaya (western New Guinea), Indonesia." Thesis, 1996. http://hdl.handle.net/2152/30179.

Full text

Abstract:

New Guinea has long been recognized by geologists as the location of geologically recent mountain building. This study combined field mapping, stratigraphic and remote sensing analysis along and near the Gunung Bijih (Ertsberg) mine road and mining district in order to analyze the geologic development of the collisional New Guinea orogen. As a result of the youthfulness and the quality of data, it is possible to constrain distinct parts of orogenic evolution to 1 or 2 m.y. The southern Central Range of New Guinea is located on the northern Australian continental margin. The southern one-third of the Central Range, exposed along the Gunung Bijih mine access road, is a 30-km-wide, north-dipping homocline exposing an apparently 18-km-thick Precambrian or Early Paleozoic to Cenozoic sequence. Following rifting in the early Mesozoic and until the Middle Miocene, the northern Australian continent was a passive margin. The Central Range of Irian Jaya formed when the Australian passive margin was subducted beneath and collided with a north-dipping subduction zone in the Middle Miocene. Litho- and biostratigraphic analysis of the New Guinea Limestone Group in the Gunung Bijih mining district and regional stratigraphic correlation indicates that the first evidence of subaerial exposure and erosion of the orogen is the widespread deposition of siliciclastic, synorogenic strata at ~12 Ma. I name this event the Central Range Orogeny. There is no evidence of an Oligocene orogenic event in the Irian Jaya region as has been described to the east in Papuan New Guinea. Deformation in the Central Range is dominated by ~12 to ~4 Ma southwest verging (210°-220°) contraction and minor east-west wrenching. This deformation is equally accommodated, there is no evidence for strain partitioning in the Central Range. Lithospheric-scale cross sections, incorporating field observations, predict the Central Range Orogeny is divided into a pre-collision and collisional stage. The pre-collision stage is the bulldozing of passive margin sediments in a north dipping subduction zone. The collision stage occurs when buoyant Australian lithosphere can not be subducted. The collision stage results in basement involved deformation and lithospheric delamination of the already subducted Australian plate.
text

APA, Harvard, Vancouver, ISO, and other styles

36

Nel, Brian Philip. "Petrography and geochemistry of iron formations of the Paleoproterozoic Koegas Subgroup, Transvaal Supergroup, Griqualand West, South Africa." Thesis, 2013. http://hdl.handle.net/10210/8762.

Full text

Abstract:

M.Sc. (Geology)
Nel, B.P. (2013). Petrography and geochemistry of iron formations of the Paleoproterozoic Koegas Subgroup, Transvaal Supergroup, Griqualand West, South Africa. MSc thesis (unpublished), University of Johannesburg, Aucklandpark, pp. 133. The Early Paleoproterozoic Koegas Subgroup comprises a succession of siltstone, mudstone, iron-‐formation, chert and carbonate rocks that overlies the iron-‐formations of the Asbestos Hills Subgroup with sharp contact. It is overlain with erosional unconformable contact by glaciogenic diamictites of the Makaganyene Formation. This study focused on the lithostratigraphy, mineralogy and geochemistry of the iron-‐ formations of the Koegas Subgroup based on fresh diamond drill core samples obtained during the Agouron scientific drilling project in South Africa in 2004. The iron formations the Koegas Subgroup are represented by a few important lithotypes, occurring in distinct sedimentary facies, which formed in unique depositional and diagenetic environments. The iron formations consist essentially of four facies, namely silicate lutite, mixed silicate-‐siderite lutite, siderite lutite and siderite peloidstone A repetitive sedimentary cycle consisting of fine-‐grained chemical lithotypes grading upward into reworked chemical lithotypes is evident throughout the Koegas Subgroup iron formations. Silicate lutite formed in deep water settings well below the wave base along a chemocline. Siderite lutite formed in shallower parts of the basin through transformation of primary ferric iron precipitate by iron respiration in presence of organic carbon. Peloidstone formed above normal wave base in shallow water by reworking of earlier siderite lutite deposits. The REE geochemistry provides important clues as to the depositional environment of the iron formation as follows. Depletion in LREE and enrichment in HREE combined with positive Y are typical of ocean water indicate that the iron formations were deposited in a marine environment. Positive Eu anomaly suggest the presence of a hydrothermal component in the ocean water from which the iron formations were deposited. Negative Ce anomalies indicate that somewhere in the marine system Ce3+ was oxidized to Ce4+ oxide, probably in the presence of free oxygen in the ocean water column (Bau and Dulski, 1996). The negative Ce anomalies seen in the Koegas iron formations are the oldest currently known from iron formations. As such the Ce anomalies most probably signify an increase in the oxygenation state of the ocean immediately prior to the rise of atmospheric oxygen as defined by Guo et al. (2009).

APA, Harvard, Vancouver, ISO, and other styles

37

Verdel, Charles Steven. "I. Cenozoic Geology of Iran: An Integrated Study of Extensional Tectonics and Related Vulcanism. II. Ediacaran Stratigraphy of the North American Cordillera: New Observations from Eastern California and Northern Utah." Thesis, 2009. https://thesis.library.caltech.edu/3631/7/Verdel_thesis.pdf.

Full text

Abstract:

I. The late Oligocene to Miocene collision of Arabia and Eurasia was preceded by ~175 My of subduction of Neotethyan oceanic crust. Associated magmatic activity includes late Triassic(?) to Jurassic plutons in the Sanandaj-Sirjan zone of southern Iran, limited Cretaceous magmatism in the Alborz Mountains of northern Iran, and widespread Eocene volcanism across central Iran. Metamorphic core complexes of Eocene age have recently been recognized in widely separated parts of Iran, suggesting that Tertiary volcanism was related to extension. Geochemical data indicate that Eocene volcanism was typical of continental arcs and was followed by less voluminous Oligocene basaltic volcanism of the type often associated with back-arc basins. This set of observations suggests that mid-Mesozoic plutons in southern Iran are the remnants of an original volcanic arc that was only weakly developed because of slow subduction rate. Magmatic activity largely ceased in southern and central Iran during the Cretaceous and shifted to the north, suggesting a period of flat slab subduction. Subsequent slab-rollback during the Eocene extended the overriding plate, forming metamorphic core complexes and inducing pressure-release melting of partially hydrated lithospheric mantle and upwelling of asthenosphere.

II. The Ediacaran Period spans from the base of cap carbonates overlying glacial deposits of the Marinoan “Snowball Earth” event to the Precambrian-Cambrian boundary, ~635 to 542 Ma. Sediments deposited during the rifting of southwest Laurentia, which are now exposed in a relatively narrow belt in the western US, are one of the best records on earth of the geological, geochemical, and geobiological events that occurred during this period. Evidence for one of the most significant of these, the final oxygenation of the oceans, is found within the upper Johnnie Formation in the southern Great Basin. C isotope data from thick, basinal facies of the Johnnie Fm. in the Panamint Range provide a more complete record of ocean chemistry associated with this event than previously determined from thinner, platformal facies. Strata in northern Utah of roughly the same age include a rift-related basalt, providing some of the youngest geologic evidence for the rifting of western Laurentia.

APA, Harvard, Vancouver, ISO, and other styles

38

"Stratigraphy, petrology, and geochemistry of the North Touak-Cape Dyer volcanic belt, and implications for the tectonic setting of the Paleoproterozoic Hoare Bay group, eastern Baffin Island." Thesis, 2012. http://hdl.handle.net/10388/ETD-2012-09-787.

Full text

Abstract:

During the Geological Survey of Canada’s Cumberland Peninsula Integrated Geoscience project a ~150km long NE-SW trending volcanic belt, now termed the North Touak-Cape Dyer volcanic belt, was mapped. The volcanic rocks that comprise the belt are dominantly green weathering komatiitic rocks with some black weathering tholeiitic occurrences. Given the similar stratigraphic position, textures, mineralogy, and geochemical characteristics of the volcanic rocks throughout the belt they have been termed the Totnes Road formation, after the locality from which they were first described. The komatiitic rocks possess numerous unusual characteristics for ultramafic volcanic rocks including: fragmental textures, lack of spinifex texture, young eruption age (Paleoproterozoic), eruption through ancient continental crust, and enrichment in the HFSEs including the REEs. This places them in the uncommon and poorly understood sub-type of komatiites termed Karasjok-type komatiites. Given the ultramafic nature of the rocks and their within-plate geochemical signatures, a mantle plume is the most likely source of these rocks, with the komatiites being sourced from the hot plume axis and the tholeiites from the cooler plume head. Incorporation and melting of mantle enriched by the addition of subduction zone recycled, garnet-bearing eclogitic material, beneath thick lithosphere could cause the rocks geochemical enrichment. Stratigraphically overlying the Totnes Road formation is a variety of chemical sedimentary rocks including chert, sulphide and silicate facies iron formation, and sulphide-rich boulders. Given their consistent stratigraphic position and parallel REE patterns, these rocks have been interpreted as a co-genetic suite and are grouped under the Clephane Bay formation, after a locality that exposes a spectacular section of the chemical rocks. The variety of lithologies is believed to be due to mixing of hydrothermal and detrital inputs during deposition within an anoxic basin. Regional correlations in the area are tentative due to the lack of available geochronological and geochemical data. Mafic-ultramafic volcanic occurrences to both the north and the south of the Cumberland Peninsula show remarkably similar geochemical characteristics to the Totnes Road formation. Thus it is possible that one plume was the source for numerous volcanic occurrences within in the region but more detailed study is required to prove or disprove this possibility.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Stratigraphie – Iran'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles