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The Late Tortonian - Early Messinian Foraminifera Record of the Abad Member (Turre Formation), Sorbas Basin, Almeria, southeast SpainBaggley, Kieron A. January 1998 (has links)
No description available.
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The tectonic evolution of Epirus, northwest GreeceWaters, David William January 1994 (has links)
No description available.
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Şerefköy-2, a New Late Miocene Mammal Locality From the Yataĝan Formation, Muĝla, SW TurkeyKaya, Tanju T., Mayda, Serdar, Kostopoulos, Dimitris S., Alcicek, Mehmet Cihat, Merceron, Gildas, Tan, Aytekin, Karakutuk, Seval, Giesler, Amanda K., Scott, Robert S. 01 January 2012 (has links)
Here we report on a new fossil locality, şerefköy-2, from the Yataĝan Basin of southwestern Turkey that preserves a well-sampled, abundant, and diverse mammal fauna. Indeed, after three field seasons, more than 1200 catalogued specimens representing 26 mammal species belonging to 14 genera make the şerefköy-2 mammalian assemblage one of the richest Late Miocene fauna from Anatolia. Five hipparionines, six bovids, including the rare and enigmatic Urmiatherium rugosifrons and the presence of Pliohyrax graecus, strongly support affinities with Late Miocene faunas from Samos Island, Greece. Through a consideration of the identified material and the subsequent comparison with material from well-known Balkan and Anatolian faunas, a Middle Turolian (MN12) age for şerefköy-2 is indicated.
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Plant-arthropod interactions in the late TertiaryTitchener, Frederick Robert January 2000 (has links)
No description available.
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Evolutionary Dynamics of Indo - Pacific Reef Corals throughout the NeogeneKate Bromfield Unknown Date (has links)
The origin of marine biodiversity in the Indo-Pacific is poorly known. Faunal turnover in scleractinian reef corals has been hypothesised over the Miocene-Pliocene boundary (~5 Ma), in the Malay Archipelago. However, there is little information available on origination and extinction events in reef corals during the same period for the broader Indo-Pacific region. This is important because many species probably had a wider distribution than previously thought, and many more genera than has previously been estimated were probably present in the Indo-Pacific during the Neogene. Here I begin to fill the gap in our knowledge by reporting on the taxonomic composition and diversity of Neogene reef coral communities sampled from Indonesia (Salayar), Papua New Guinea (New Britain), and Fiji (Vanua Balavu). Sampling locations were chosen on their reported age, fossil content and preservation quality. Ages were refined using foraminiferal assemblages and Strontium 87/86 isotope ages of samples collected at the sampling locations. This dual approach confirms a middle Miocene to early Pleistocene age range for the collection. I described 155 species of reef forming corals collected across an Indo-Pacific longitudinal gradient. Twenty-two constitute new, extinct species from the genera Alveopora, Astreopora, Caulastrea, Cyphastrea, Echinopora, Euphyllia, Galaxea, Leptoria, Leptoseris, Madracis, Montipora, Platygyra, Symphyllia and Turbinaria. A further 42 taxa could not be assigned to species level due to poor preservation, but may well be additional new, extinct species. I uncovered a general pattern of coral turnover across the Indo-Pacific by investigating the degree to which coral communities (using both presence/absence and relative abundance of both coral species and genera) varied with water depth, time and geographical distribution. Coral communities were found to vary with global sea level and time. Thus global changes in sea level through time potentially drove extinction and origination in Indo-Pacific Neogene corals. Inverse Lyellian analysis indicates that of species present in the Miocene in New Britain, a mean of 41.8% are now extinct, possibly resulting from restricted flow of oceanic currents in that region. Indonesia (mean = 9.4%); and Fiji (mean = 6.6%) both had significantly lower proportions of extinct species. However, there is a decline in the number of extinct species found at any location from the middle Miocene (mean = 23.2%) to the early Pleistocene (mean = 1.8%). This study supports previously proposed models of an early Pliocene turnover event in Scleractinia in the Indo-Pacific.
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Neogene seismotectonics of the south-central Chile margin : subduction-related processes over various temporal and spatial scalesMelnick, Daniel January 2007 (has links)
The Andean orogen is the most outstanding example of mountain building caused by the subduction of oceanic below continental lithosphere. The Andes formed by the subduction of the Nazca and Antarctic oceanic plates under the South American continent over at least ~200 million years. Tectonic and climatic conditions vary markedly along this north-south–oriented plate boundary, which thus represents an ideal natural laboratory to study tectonic and climatic segmentation processes and their possible feedbacks. Most of the seismic energy on Earth is released by earthquakes in subduction zones, like the giant 1960, Mw 9.5 event in south-central Chile. However, the segmentation mechanisms of surface deformation during and between these giant events have remained poorly understood. The Andean margin is a key area to study seismotectonic processes because of its along-strike variability under similar plate kinematic boundary conditions.
Active deformation has been widely studied in the central part of the Andes, but the south-central sector of the orogen has gathered less research efforts. This study focuses on tectonics at the Neogene and late Quaternary time scales in the Main Cordillera and coastal forearc of the south-central Andes. For both domains I document the existence of previously unrecognized active faults and present estimates of deformation rates and fault kinematics. Furthermore these data are correlated to address fundamental mountain building processes like strain partitioning and large-scale segmentation.
In the Main Cordillera domain and at the Neogene timescale, I integrate structural and stratigraphic field observations with published isotopic ages to propose four main phases of coupled styles of tectonics and distribution of volcanism and magmatism. These phases can be related to the geometry and kinematics of plate convergence. At the late Pleistocene timescale, I integrate field observations with lake seismic and bathymetric profiles from the Lago Laja region, located near the Andean drainage divide. These data reveal Holocene extensional faults, which define the Lago Laja fault system. This fault system has no significant strike-slip component, contrasting with the Liquiñe-Ofqui dextral intra-arc system to the south, where Holocene strike-slip markers are ubiquitous. This contrast in structural style along the arc is coincident with a marked change in along-strike fault geometries in the forearc, across the Arauco Peninsula. Thereon I propose that a net gradient in the degree of partitioning of oblique subduction occurs across the Arauco transition zone. To the north, the margin parallel component of oblique convergence is distributed in a wide zone of diffuse deformation, while to the south it is partitioned along an intra-arc, margin-parallel strike-slip fault zone.
In the coastal forearc domain and at the Neogene timescale, I integrate structural and stratigraphic data from field observations, industry reflection-seismic profiles and boreholes to emphasize the influence of climate-driven filling of the trench on the mechanics and kinematics of the margin. I show that forearc basins in the 34-45°S segment record Eocene to early Pliocene extension and subsidence followed by ongoing uplift and contraction since the late Pliocene. I interpret the first stage as caused by tectonic erosion due to high plate convergence rates and reduced trench fill. The subsequent stage, in turn, is related to accretion caused by low convergence rates and the rapid increase in trench fill after the onset of Patagonian glaciations and climate-driven exhumation at ~6-5 Ma. On the late Quaternary timescale, I integrate off-shore seismic profiles with the distribution of deformed marine terraces from Isla Santa María, dated by the radiocarbon method, to show that inverted reverse faulting controls the coastal geomorphology and segmentation of surface deformation. There, a cluster of microearthquakes illuminates one of these reverse faults, which presumingly reaches the plate interface. Furthermore, I use accounts of coseismic uplift during the 1835 M>8 earthquake made by Charles Darwin, to propose that this active reverse fault has been mechanically coupled to the megathrust. This has important implications on the assessment of seismic hazards in this, and other similar regions.
These results underscore the need to study plate-boundary deformation processes at various temporal and spatial scales and to integrate geomorphologic, structural, stratigraphic, and geophysical data sets in order to understand the present distribution and causes of tectonic segmentation. / Die Anden sind eine einzigartige Gebirgskette entstanden aus der Subduktion von ozeanischer unter kontinentale Lithosphäre. Seit mehr als 200 Millionen Jahren bewirkt die Subduktion der ozeanischen Nazca- und Antarktisplatte unter den Südamerikanischen Kontinent eine stete Entwicklung des aktiven Plattenrandsystems. Entlang der Plattengrenze ändern sich die tektonischen und klimatischen Bedingungen in markanter Weise und machen dieses Orogen zu einem idealen natürlichen Laboratorium für das Studium tektonischer und klimatischer Prozesse und deren rückgekoppelte Wechselwirkungen. Der grösste Teil der seismischen Energie auf der Erde wird durch Erdbeben an Subduktionszonen freigesetzt, wie das spektakulärste Beispiel des Valdivia-Bebebens von 1960 im süd-zentral chilenischen Küstenbereich – mit Mw 9,5 das stärkste je gemessene seismische Ereignis, unterstreicht. Die Verteilungsmechanismen der Oberflächendeformation während und zwischen solchen gewaltigen Vorgängen blieben jedoch weitgehend unverstanden. Wegen seiner im Streichen veränderlichen Eigenschaften bei ähnlich bleibenden plattenkinematischen Randbedingungen nimmt die Subduktionszone des Anden-Orogens eine Schlüsselstellung für das Studium seismotektonischer Segmentationsprozesse ein.
Aktive Deformationsprozesse sind im zentralen Teil der Anden in grösserem Umfang untersucht worden, während der mittlere bis südliche Abschnitt des Orogens bisher weniger Bearbeitung fand. Die vorliegende Arbeit ist auf die seismotektonischen Prozesse des Neogen und Spätquartärs in der Hauptkordillere und dem Küstenbereich der südlichen Zentralanden konzentriert. In beiden Strukturzonen kann die Existenz bisher nicht bekannter aktiver Störungen belegt werden und es werden Abschätzungen der Deformationsraten sowie der Kinematik präsentiert. Diese Daten bilden desweiteren die Basis, um Aussagen zu grundlegenden gebirgsbildenden Prozessen, der Verformungsverteilung und der gross-skaligen Segmentation zu treffen.
Für das Neogen im untersuchten Abschnitt der Hauptkordillere sind strukturelle und stratigraphische Geländebeobachtungen durch publizierte Isotopendaten ergänzt worden, so dass vier Hauptphasen mit jeweils spezifischem tektonischen Stil und Verteilungsmustern von Vulkanismus und Magmatismus unterschieden werden können. Auf der spätpleistozänen Zeitskala sind die Geländebeobachtungen mit seismischen und bathymetrischen Seeprofilen aus der Lago-Laja-Region kombiniert worden, die sich nahe der Wasserscheide der Anden befinden. Diese Daten belegen extensionale holozäne Störungen, die das Lago-Laja-Störungssystem bestimmen. Im Gegensatz zum dextralen Liquiñe-Ofqui-System im Süden, wo holozäne, dextrale Blattverschiebungen allgegenwärtig sind, besitzt dieses Störungssystem keine signifikante Blattverschiebungskomponente. Dieser Kontrast entlang der Kordilliere fällt mit einer markanten Änderung der Störungsmuster im Forearc zusammen. Im Norden verteilt sich die randparallele Komponente der schrägen Subduktion auf eine breite Zone diffuser Verformung, während sie im Süden entlang einer Intra-arc- und randparallelen Blattverschiebungszone partitioniert auftritt.
Im Küstenbereich werden Struktur- und stratigraphische Daten aus Geländebeobachtungen mit reflektionsseismischen Profilen und Bohrlochmessdaten verbunden, um Information zum Einfluss einer klimatisch-gesteuerten Auffüllung des Grabens auf die Mechanismen und die Kinematik des Randes während des Neogen zu erhalten. Es zeigt sich, dass Forearc-Becken im Segment bei 34–45° S eozäne bis frühpliozäne Dehnung und Subsidenz aufzeigen, denen spätpliozäne und noch aktive Hebung und Verkürzung folgten. Das erste Stadium kann mit tektonischer Erosion infolge hoher Plattenkonvergenzraten und geringerer Grabenfüllung erklärt werden. Das nachfolgende Stadium hingegen ist mit Akkretionsprozessen zu erklären, die durch geringe Konvergenzraten und gesteigerte Grabenauffüllung nach dem Einsetzen der Patagonischen Vereisung und klimagesteuerter Exhumierung vor etwa 6–5 Ma verursacht wurden. Auf der spätpleistozänen Zeitebene werden seismische Profile mit der Oberflächenentwicklung aus deformierten, 14C-datierten, marinen Terrassen der Isla Santa María integriert und gezeigt dass die Küstenmorphologie und die Segmentation der Oberflächendeformation von Aufschiebungen kontrolliert werden. In diesem Gebiet zeichnet ein Cluster von Mikrobeben eine dieser Störungen, die vermutlich die Plattengrenzfläche erreicht, deutlich nach. Desweiteren zeigen Berechnungen der koseismischen Hebung während des Erdbebens von 1835 mit M>8 nach Aufzeichnungen von Charles Darwin, dass diese aktive Verwerfung mechanisch an die Subduktionszone gekoppelt war und durch das Ereignis von 1835 aktiviert wurde. Diese Erkenntnisse haben grosse Bedeutung für die Abschätzung der seismischen Gefährdung in der Region.
Die gewonnenen Ergebnisse dieser Arbeit unterstreichen den Bedarf an integrierten Untersuchungen der Deformationsprozesse an aktiven Plattenrändern in verschiedenen Zeit- und Raumskalen, ebenso wie die Notwendigkeit, diese mit geomorphologischen, strukturellen und geophysikalischen Datensätzen zu verknüpfen, um einen Beitrag zum Verständnis der gegenwärtigen Verteilung und Ursachen der tektonischen Segmentation sowie der Gefährdungsabschätzung zu leisten.
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Neogene stratigraphic relationships within the Nam Con Son Basin, offshore Vietnam resulting from tectonics, eustasy, and sediment fluxWright, Christine M. 15 May 2009 (has links)
The South China Sea is a region of significant importance in terms of the records
of SE Asian tectonics, including Tibetan Plateau uplift, and the onset and evolution of
the East Asian monsoon. The Mekong River has been a dominant sediment source since
at least late Miocene time and has headwaters on the eastern Tibetan Plateau.
Understanding the Pliocene to Recent stratigraphy of the paleo-Mekong Delta and
associated shelf-edge deposits aids in understanding changes in accommodation, sea
level, and sediment supply. This record might then be useful in interpreting the longterm
history of basin evolution in the Nam Con Son Basin.
Nine sequence boundaries and associated sequences are recognized along the late
Miocene to latest Pleistocene shelf in the East Nam Con Son Basin. Age constraints
were assigned to key stratigraphic horizons by correlating sequence boundaries with
published sea level curves. Accommodation in the study area is controlled by shelf -edge
compaction, rift-related thermal subsidence, non-rift-related anomalous subsidence,Two primary sources supplied sediment to the southwestern South China Sea
during Pliocene to Recent time and likely include the paleo-Mekong Delta and a fluviodeltaic
system originating from the Sunda Shelf, such as the Molengraaff River. Changes
in thickness, area, and location of Pliocene to Recent shelf-edge delta deposits reflect
changes in accommodation and sediment supply over time, as well as progradation of
the shelf edge during Pliocene to Recent time and avulsion of the shelf edge delta.
Anomalous subsidence of LGM shelf edge deposits is estimated at approximately
40-50 m deeper than expected. The current depth of the LGM deltaic wedge may
indicate renewed rapid tectonic subsidence during the last 18,000 yrs, possible
compaction effects or a combination of these.
eustatic change, and shelf edge faulting.
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Stratigraphic and structural analysis of the Neogene sediments of the offshore portion of the Salina del Istmo Basin, southeastern MexicoGómez-Cabrera, Pedro Tomás 28 August 2008 (has links)
Not available / text
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The Atlantic, the Amazon, and the Andes : neogene climate and tectonics viewed from Ceara Rise, western tropical AtlanticHarris, Sara E. 29 May 1998 (has links)
Graduation date: 1999
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Φυσική συμπεριφορά των εκσκαπτώμενων αργιλικών ημιβράχων κατά τη διάνοιξη της σήραγγας Τράπεζας της Σ.Γ.Υ.Τ. Κιάτου – ΑιγίουΝταντάμη, Παναγιώτα 31 May 2012 (has links)
Στην εργασία αυτή καταγράφονται οι τεχνικογεωλογικές συνθήκες κατά τη διάνοιξη της σιδηροδρομικής σήραγγας της Τράπεζας που έχει συνολικό μήκος 3048,12 μ. Η διάτρηση γίνεται μέσα σε μεταλπικά ιζήματα του νεογενούς και συγκεκριμένα μέσα σε στιφρές μάργες με τοπικές ενστρώσεις χαλαρών κροκαλοπαγών. Λόγω της φύσης των υλικών ήταν απαραίτητη η χρήση δοκών προπορείας, αγκυρίων προπορείας και όλων των μέσων προσωρινής αντιστήριξης (πλαίσια, εκτοξευόμενο σκυρόδεμα, αγκύρια, πλέγμα) και όπου υπήρξε αυξημένη υδροφορία, χρήση μεμβρανών και συστηματικές αποστραγγιστικές οπές.
Η έρευνα εντοπίζεται στο σχηματισμό του κατώτερου ορίζοντα των Νεογενών και συγκεκριμένα στους σχηματισμούς των μαργολίθων – ιλυολίθων οι οποίοι παρουσιάζουν συμπεριφορά σκληρών εδαφών – μαλακών βράχων και φιλοξενούν το μεγαλύτερο τμήμα της σήραγγας.
Έγινε συστηματική δειγματοληψία από τα μέτωπα εκσκαφής με τη μορφή δειγμάτων μεγάλων διαστάσεων (block samples) που μεταφέρονταν αμέσως στο εργαστήριο όπου και γινόταν η διαμόρφωσή τους για τη δοκιμή της χαλάρωσης, καθώς και των δοκιμών του προσδιορισμού των φυσικών ιδιοτήτων .
Στα δείγματα που διαμορφώθηκαν έγιναν δοκιμές προσδιορισμού των φυσικών παραμέτρων και συγκεκριμένα έγιναν οι παρακάτω δοκιμές: δοκιμές φυσικής υγρασίας, προσδιορισμός των ορίων συνεκτικότητας (όρια Atterberg), προσδιορισμός του ειδικού βάρους υλικού λεπτότερου υλικού των 2mm, κοκκομετρική ανάλυση με κόσκινα αλλά και με αραιόμετρο (μέθοδος Stoke’s), προσδιορισμός φαινόμενου βάρους συνεκτικών υλικών, και τέλος ο προσδιορισμός του δείκτη χαλάρωσης πετρώματος. / In this work they are listed the technical – geological conditions for the opening of the railway tunnel of the Bank that has a total length of 3048.12 m. The drilling takes place in post alpine sediments of the neogene and particularly in dense marls with local intercalations of loose conglomerates. Due to the nature of the materials it was necessary the use of head – beams, head – anchors and all temporary retaining means ( frames, sprayed concrete, anchors, mesh ) and in the points of increased aquifer it was made use of membranes and systematic drainage holes.
The investigation is located in the formation of the lower horizon of the neogene and particularly in the formations of the marlstones – siltstones that present a behavior of hard soils – soft rocks and they host the biggest part of the tunnel.
It took place a systematic sampling from the fronts of excavation with the form of samples of big dimensions ( block samples) that were transferred immediately to the laboratory, where their formation was taken place for the sag test as well as the tests of the determination of the physical properties.
In the samples that were formed, tests of the determination of the physical parameters were taken place and particularly the following tests took place: tests of natural moisture, the determination of consistency limits ( Αtterberg limits ), the determination of the specific weight of a material of finer material than 2mm\, the particle analysis with sieves as well as with an hydrometer (Stoke’s method), the determination of unit weight of consistent materials and finally the determination of the rock sag rate.
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