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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Geomorfologia do baixo curso do rio Ivinhema, MS: uma abordagem morfogenética e morfoestrutural

Fortes, Edison [UNESP] 31 July 2003 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:32:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-07-31Bitstream added on 2014-06-13T21:03:59Z : No. of bitstreams: 1 fortes_e_dr_rcla.pdf: 3795155 bytes, checksum: 325b5a6aa2479f67ec71e4954cc2fa16 (MD5) / O rio Ivinhema constitui um importante afluente da margem direita do rio Paraná e drena uma série de terraços, superfícies geomorfológicas e feições associadas, a despeito de as baixas declividades sugerirem, numa análise preliminar, um relevo monótono e homogêneo. A presente tese teve como propósito maior o estudo das feições do relevo na área do baixo curso do rio Ivinhema, buscando compreender a sua evolução, no contexto de suas estruturas, de suas morfologias e de seus depósitos sedimentares. Os estudos, realizados na escala 1:60.000, permitiram a identificação de terraços, planícies, leques aluviais e superfícies erosivas. O Terraço Alto (TRA) corresponde à superfície mais elevada e antiga da área de trabalho; o Terraço Médio (TRM), identificado pela grande quantidade de depressões e lagos, que emprestam uma característica peculiar a essa superfície, pois representam um nível rebaixado por processos tectoerosivos do Terraço Alto. O Terraço Baixo (TRB) apresenta uma série de paleocanais posicionados em até 10m de altura em relação ao canal atual do rio Ivinhema, denotando atividade tectônica holocênica. A Planície do Rio Ivinhema divide-se em alta (PRIa) e baixa (PRIb), e corresponde a uma superfície plana, cuja largura aumenta para montante; freqüentemente ela pode ser inundada pelas águas do rio Ivinhema, à exceção do trecho próximo ao Terraço Baixo que se encontra soerguido. A planície do rio Paraná representa igualmente uma área plana, freqüentemente inundada pelas águas do rio homônimo, e apresenta, em seu interior, paleoilhas, cuja coalescência teria sido responsável pela formação da referida planície. Os Leques Aluviais Alto (LEA) e Baixo (LEB) constituem cones de dejeção, cuja diferenciação é de caráter topográfico e temporal...
32

Combining Tectonic Geomorphology and Paleoseismology for Understanding of Earthquake Recurrence

January 2016 (has links)
abstract: There is a need to understand spatio-temporal variation of slip in active fault zones, both for the advancement of physics-based earthquake simulation and for improved probabilistic seismic hazard assessments. One challenge in the study of seismic hazards is producing a viable earthquake rupture forecast—a model that specifies the expected frequency and magnitude of events for a fault system. Time-independent earthquake forecasts can produce a mismatch among observed earthquake recurrence intervals, slip-per-event estimates, and implied slip rates. In this thesis, I developed an approach to refine several key geologic inputs to rupture forecasts by focusing on the San Andreas Fault in the Carrizo Plain, California. I use topographic forms, sub-surface excavations, and high-precision geochronology to understand the generation and preservation of slip markers at several spatial and temporal scales—from offset in a single earthquake to offset accumulated over thousands of years. This work results in a comparison of slip rate estimates in the Carrizo Plain for the last ~15 kyr that reduces ambiguity and enriches rupture forecast parameters. I analyzed a catalog of slip measurements and surveyed earth scientists with varying amounts of experience to validate high-resolution topography as a supplement to field-based active fault studies. The investigation revealed that (for both field and remote studies) epistemic uncertainties associated with measuring offset landforms can present greater limitations than the aleatoric limitations of the measurement process itself. I pursued the age and origin of small-scale fault-offset fluvial features at Van Matre Ranch, where topographic depressions were previously interpreted as single-event tectonic offsets. I provide new estimates of slip in the most recent earthquake, refine the centennial-scale fault slip rate, and formulate a new understanding of the formation of small-scale fault-offset fluvial channels from small catchments (<7,000 m2). At Phelan Creeks, I confirm the constancy of strain release for the ~15,000 years in the Carrizo Plain by reconstructing a multistage offset landform evolutionary history. I update and explicate a simplified model to interpret the geomorphic response of stream channels to strike-slip faulting. Lastly, I re-excavate and re-interpret paleoseismic catalogs along an intra-continental strike-slip fault (Altyn Tagh, China) to assess consistency of earthquake recurrence. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2016
33

Eolianite and beachrocks in western coast of CearÃ: Meaning Sedimentological and neotectonic / Eolianitos e beachrocks no litoral oeste do CearÃ: significado sedimentolÃgico e neotectÃnico

Ãquila Ferreira Mesquita 27 March 2015 (has links)
CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Os depÃsitos holocÃnicos do litoral oeste do Cearà encontram-se em intrÃnseca relaÃÃo com a flutuaÃÃo do nÃvel relativo do mar no Holoceno Tardio, possivelmente controlada por atividade neotectÃnica. A partir do estuÃrio do rio Aracatimirim (provÃvel projeÃÃo do Lineamento Transbrasiliano), a Ãrea de estudo foi subdividida em setor Icaraà de Amontada (leste) e setor Itarema (oeste). O setor leste compreende planÃcies costeiras com grande presenÃa de eolianitos e beachrocks associados. A partir da anÃlise faciolÃgica dos depÃsitos de eolianitos, foi possÃvel identificar cinco fÃcies eÃlicas interpretadas como paleocampos de dunas frontais e cadeias de dunas barcanÃides associadas a extensÃes lineares. Esses depÃsitos foram originados em campos de dunas transgressivas em nÃvel eustÃtico alto sucedido por um recuo generalizado do nÃvel marinho local, este Ãltimo responsÃvel pela incisÃo fluvial e cimentaÃÃo de beachrocks e eolianitos. Em contrapartida, o setor oeste tambÃm registra dois momentos distintos do nÃvel relativo do mar, responsÃvel pela formaÃÃo de uma paleofalÃsia em nÃvel de mar alto e um sistema de barreiras regressivas em eventos de recuo do nÃvel do relativo do mar. Admitindo-se nenhum contraste na eustasia e suprimento sedimentar em ambos os setores, tal diferenÃa pode estar relacionada a movimentos diferenciais de blocos adjacentes à terminaÃÃo offshore do Lineamento Transbrasiliano, afetando a acomodaÃÃo sedimentar. Para os registos do nÃvel relativo do mar no Holoceno, supÃe-se que nÃvel acima do atual nÃo foi alcanÃado para a costa equatorial do Brasil, exceto na Ãrea em estudo, onde foram registrados paleonÃveis marinhos a 1,7 m e 1,0 acima do nÃvel mÃximo atual de preamares para SantarÃm e Volta do Rio, respectivamente. Essa relaÃÃo atende a hipÃtese de atividade neotectÃnica em blocos adjacentes ao Lineamento Transbrasiliano como o principal mecanismo na modificaÃÃo do espaÃo de acomodaÃÃo da bacia e recuo do nÃvel marinho. A partir dos dados morfoestruturais em tabuleiros prÃ-litorÃneos, identificou-se um leve arqueamento positivo da superfÃcie de topo dos tabuleiros no setor oeste, em contraste a uma pequena anomalia de relevo positivo (soerguimento relativo de aproximadamente 10 m) na extremidade do setor leste. Concomitante a essa movimentaÃÃo genÃrica, encontramse sÃries de movimentos transcorrentes dextrais em fraturas NE-SW com componentes transpressionais e transtracionais, promovendo movimentos verticais diferenciados de pequena amplitude. Dessa forma, postula-se que a maior componente de soerguimento, caracterÃstico do setor Icaraà de Amontada, tenha impulsionado uma maior destruiÃÃo de espaÃo para acomodaÃÃo de sedimentos no lado leste. Dessa forma, que o recuo do nÃvel marinho relativo atingiu magnitude maior nesse setor do que no setor Itarema, o que possibilitou a incisÃo fluvial no setor leste e instalaÃÃo de um sistema de barreiras regressivas no setor oeste. Esse modelo explica o contraste entre geometria e ambientes deposicionais em um compartimento relativamente pequeno do litoral noroeste do CearÃ. Entretanto, essa hipÃtese precisa ser melhor investigada e testada a fim de se obter um modelo mais robusto para a evoluÃÃo da Ãrea em questÃo, sobretudo em relaÃÃo a correlaÃÃes laterais entre os depÃsitos sedimentares, cinemÃtica e dinÃmica no contexto neotectÃnico. / The Holocene deposits of the western coast of Cearà are in close relationship with the fluctuation of the relative sea level in the Late Holocene, possibly controlled by neotectonic activity. Using the mouth of the Aracatimirim River (likely projection of Transbrasiliano Lineament) as reference, the study area was divided into Icaraà de Amontada sector (east) and Itarema (west) sector. The eastern sector comprises coastal plains with great presence of associated eolianite and beachrocks. From the facies analysis of eolianite deposits were identified five aeolian facies interpreted as frontal dunes and barcanoid dune chains associated with linear extensions. These deposits were originated in transgressive dune fields, during rising eustatic level, succeeded by a general fall of the local sea level, the latter responsible for river incision and cementation of beachrocks and eolianites. In contrast, the western sector also records two different times of relative sea level, responsible for the formation of a paleocliff in rising sea level and a system of regressive barriers in falling sea level event. Assuming no contrast in eustasy and sediment supply in both sectors, this difference may be related to differential movement of adjacent blocks offshore termination of Transbrasiliano Lineament, affecting sedimentary accommodation. For the record of relative sea level during the Holocene, it is assumed that the current level was not reached for the equatorial coast of Brazil, except in the study area, where were registered marine paleolevels from 1.7 m to 1.0 m above the current level of maximum high tides to Santarem and Rio Volta, respectively. This relationship strengths the hypothesis of neotectonic activity in locks adjacent to Transbrasiliano Lineament as the main mechanism on modification the accommodation space of the basin and retreat of sea level. From the morphostructural data in pre-coastal trays, were identified a positive smooth arching of the pre-coastal plateaus top surface in the western sector, in contrast to a small positive anomaly of relief (uplift of approximately 10 m) at the east end sector. Concomitant with this generic deformation, there was some dextral transcurrent movements in NE-SW fractures with transpressional and transtensional components,providing different vertical movements of small amplitude. Thus, it is postulated that the higher uplifting component, characteristic of Icarai de Amontada sector, has caused more destruction of accommodation space for sediment on the east side than in the west side,causing river incision in the eastern sector and installation of a regressive barriers system of in the western sector. This model explains the contrast between geometry and depositional environments in a relatively small compartment in northwestern coast of CearÃ. However, this hypothesis needs to be investigated and tested in order to obtain a more robust model for the evolution of the area, especially in relation to lateral correlations between sedimentary deposits, kinematics and dynamics in the neotectonic context.
34

Relações entre a neotectonica e o coluvionamento no Municipio de Atibaia (SP) / Relationship between neotectonics and colluvial deposits in Atibaia County (SP-Brazil)

Monteiro-da-Costa, Paulo Sergio 08 September 2005 (has links)
Orientador: Antonio Carlos Vitte / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-04T21:08:11Z (GMT). No. of bitstreams: 1 Monteiro-da-Costa_PauloSergio_M.pdf: 13167364 bytes, checksum: 3349112f9c1df10c4ab55f72f26de174 (MD5) Previous issue date: 2005 / Resumo: A presente pesquisa se insere no âmbito da história geomorfológica cenozóica do Sudeste do Brasil, em áreas de domínio do cristalino proterozóico, dentro da Província Geomorfológica do Planalto Atlântico do Estado de São Paulo. Partindo de uma abordagem pluridisciplinar, correlacionamos indícios e evidências de fenômenos paleoambientais, e estabelecemos relações entre as atividades neotectônicas do Quaternário e as formações superficiais argilosas alóctones, contíguas nas colinas da área urbana e periurbana do município de Atibaia, tipicamente representadas por LATOSSOLOS Vermelho Amarelos. O estudo discute duas vertentes interpretativas para os referidos depósitos: como partes de uma mesma seqüência deposicional pedimentar plio-pleistocênica, envolvendo alternâncias climáticas e dissecada pela rede de drenagem recente, ou como resultado de diferentes situações deposicionais e retrabalhamentos, relacionados a reativações quaternárias de fallias geológicas presentes na área. Por meio do uso de perfis topográficos, análise de perfis de rios, anomalias de drenagem realçadas pela relação entre declividades e extensões de cursos (RDE-trecho), determinações granulométricas dos depósitos e determinação geocronológica por Termoluminescência (TL) e Luminescência Opticamente Estimulada (LOE), é possível mostrar muitas evidências de movimentações quaternárias e retraballiamento dos depósitos. Sem excluir a primeira hipótese, os resultados suportam a segunda interpretação acima citada, conduzindo nossas conclusões para a ocorrência de neotectônica cenozóica até o Pleistoceno Superior / Abstract: The present research is ambiented at the Cenozoic geomorphological history of the Southeastem Brazil, in the Proterozoic crystalline domain, inside the geomorphological province of the Planalto Atlântico, in State of São Paulo. Starting from a multidisciplinary approach, we correlated signs and evidences of palaeoenvironmental phenomena and stabilished relationships between the Quaternary neotectonic activities and the allochthonous clay texture superficial deposits, contiguous on the hills of urban and periurban areas of Atibaia County, typically represented by Oxisols (Typic Acrorthox). This study discuss two distinct interpretations for the refered deposits: like parts of the same depositional pliocenic-pleistocenic pedimental sequence, involving climatic changes and peneplanation by the recent drainage net, or as result of different depositional sequences and reworks, related to Quaternary geological faults reactivations in the area. Using topographic profiles, stream-profiles analysis, drainage anomalies enhanced by Hack's stream-gradient index of sections, soil granulometric determinations and absolute age determination by termoluminescence (TL) and optically stimulated luminescence (OSL), we could show many signs of Quaternary movements and reworks of the deposits. Without exc1uding the first hypothesis, the results support the second interpretation cited above, leading our conc1usions to the occurrence of Cenozoic neotectonics until Upper Pleistocene / Mestrado / Análise Ambiental e Dinâmica Territorial / Mestre em Geografia
35

Gráben Ribeirão das Lajes, RJ : evolução estrutural cenozoica e morfotectônica /

Real, Sílvia January 2019 (has links)
Orientador: George Luiz Luvizotto / Resumo: O Gráben Ribeirão das Lajes (GRL) foi mapeado no limite entre as escarpas da Serra do Mar e o Gráben da Guanabara, no estado do Rio de Janeiro, Brasil. O presente estudo buscou caracterizar a configuração e evolução tectônica cenozoica do GRL a partir de métodos que integram procedimentos em laboratório e trabalhos de campo, envolvendo Geologia Estrutural e Geomorfologia Tectônica. Esta bacia tipo gráben encontra-se encaixada na estrutura pretérita NE-SW do embasamento pré-cambriano, composto de gnaisse bandado milonítico da Unidade Arcádia-Areal, juntamente com ortognaisses e granitoides do Arco Magmático Rio Negro. Essas rochas estão intrudidas por diques de diabásio cretáceos de direção NE-SW. O registro sedimentar está associado, principalmente, aos depósitos aluvionares e coluvionares, que se estendem por 20 km de comprimento por 9 km de largura, expostos de maneira irregular e separados por altos intrabacinais. As características da rede de drenagem e do relevo da área, somados aos inúmeros e persistentes lineamentos, mostram, em conjunto com os dados levantados em campo, que os traços principais se associam às fraturas. O GRL é uma estrutura alongada e estreita delimitada por falhas NE-SW, em ambas as bordas, e compartimentada fundamentalmente por fraturas de direção NW-SE e E-W. O primeiro evento de formação do GRL se relaciona com as falhas normais NE-SW do embasamento, equivalente ao processo de geração das bacias do Sistema de Riftes Cenozoicos do Sudeste do Brasil... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Ribeirão das Lajes Graben (RLG) was mapped at the boundary between Serra do Mar escarpments and Guanabara Graben, in the state of Rio de Janeiro, Brazil. The present study aimed to characterize the Cenozoic tectonic evolution and shape of RLG from methods which incorporate procedures in laboratory and field work, involving structural geology and tectonics geomorphology. This basin was developed on thrust-sheared precambrian NE-SW substrate, consisting of banded milonytic gneisses from the Arcadia-Areal Unit, along with orthognaisses and granitoids from the Rio Negro Magmatic Arc. These rocks are intruded by cretaceous diabase dikes with NE-SW direction. The sedimentary record is mainly associated with alluvial and colluvial deposits, extending 20 km long and 9 km wide, irregularly exposed and separated by intrabacinal highs. The drainage network and relief characteristics, added to the numerous and persistent lineaments, even along with the data collected in the field, demonstrate that the main features are associated to fractures. This elongated and narrow graben is delimited by NE-SW faults at both edges, in addition to NW-SE and E-W fractures which compartmentalize it. The RLG was formed due to recognized NE-SW normal faults, event related to Cenozoic Rift System of Southeastern Brazil generation process. NE-SW structures are expressive in the fluvial system, morphotectonic pattern and preferential erosion and sedimentation zones. In a local scale, field-recognized high-an... (Complete abstract click electronic access below) / Mestre
36

The Quaternary Geology of the Eastern Side of the Greys River Valley and the Neotectonics of the Greys River fault in Western Wyoming

Allen Jones, L. C. 01 May 1995 (has links)
The Greys River fault is the easternmost active normal fault associated with Basin and Range extension in the lntermountain seismic belt. It is a north south trending normal fault, located in the Sevier-age fold and thrust belt of western Wyoming , and bounds the west side of the Wyoming Range . The fault is at least 54 km long , and juxtaposes Permo-Pennsylvanian Wells Formation against various Triassic formations . Throw ranges from 100-1000 m. Seismic reflection data suggest that the Greys River fault is a listric normal fault that soles into the Darby thrust at depth. The fault offsets late Quaternary deposits on the west flank of the Wyoming Range. These deposits were mapped and differentiated on the basis of provenance and weathering characteristics. Four sets of moraines were identified in the study area. The moraines segregated into a local four-fold relative age sequence based on topographic position and relative dating parameters. The four-fold relative age sequence was correlated to Blackwelder's original Rocky Mountain glacial chronology. The most extensive glacial deposits were correlated to the late Pinedale glacial advance. Alluvial deposits associated with the Pinedale glacial cycle also contain evidence for late Quaternary faulting on the Greys River fault. Maximum vertical surface displacements of late Quaternary deposits range from 8.6 m in Blind Bull Creek to 8.3 m in Box Canyon, 25 kilometers to the south. Between these points, vertical surface offset ranges from 3 to 8.2 meters. Three trenches were excavated in a late Pinedale alluvial terrace complex in Sheep Creek across a 7.5-meter scarp, a 3.1-meter scarp, and a 7.5-meter scarp-graben. The trenches revealed evidence for two paleoseismic displacements, the ages of which were constrained by eight radiocarbon dates. The most recent event involved a maximum displacement of 4.5 meters and occurred between 2110 +/- 60 and 2910 +/- 60 14C years BP. The earlier event was associated with a maximum observed displacement of 3.2 meters and occurred between 5080 +/- 60 and 5310 +/- 60 14C years BP. The moment magnitudes for these events, calculated from displacement and surface rupture length , range from Mw = 6.9 to 7.4 for both events. Scarp heights indicate an uplift rate of 1.11 mm / year. If the late Pinedale alluvium is 14,000 years old, then it appears no events occurred between 14,000 yr BP and 5310 14C yr BP, and two events have occurred between 5310 14C yr BP and 2110 14C yr BP. Such irregular recurrence interval is typical for normal faults in the Basin and Range and makes long-term prediction difficult.
37

Studium současných geodynamických procesů v oblasti hronovsko-poříčského zlomového pásma / Study of present-day geodynamic processes in the area of Hronov-Poříčí Fault Zone

Stejskal, Vladimír January 2011 (has links)
The presented PhD thesis deals with present-day geodynamic processes in the south- western part of Broumov Highland, with a special attention paid to the seismoactive Hronov- Poříčí Fault Zone (HPFZ). Compared to the rest of the Bohemian Massif the studied area exhibits relatively increased level of tectonic activity, which is evidenced by local seismicity and by presence of CO2-rich mineral waters. The present-day activity of geodynamic processes is studied by means of various geomorphological, geotechnical, geophysical and hydrological methods. Following processes and features were studied: activity of slope movements, seismic activity, present-day tectonic movements, relations between landforms and joint and fault tectonics. Based on the previous experience obtained by the author in the seismoactive area of Western Bohemia, groundwater observational network was set up in deep boreholes, in order to detect anomalies related to the tectonic activity of the studied area. The thesis represents a contribution to the deeper understanding of the studied area and also a contribution in respect of possible applications of some new methods that can be used in research of zones with relatively increased tectonic activity inside of stable areas of Central Europe. From geomorphological point of view, the...
38

Neo- And Seismo-tectonic Characteristics Of The Yenigediz (kutahya) Area

Gurboga, Sule 01 December 2011 (has links) (PDF)
Erdogmus-Yenigediz graben is one of the major structural elements of Aksehir-Simav Fault System (ASFS), which is a major extensional structure in the southwestern Anatolian extensional neotectonic province (SWAEP). It is about 6-10-km-wide, 15-km-long and approximately ENE-trending and is actively growing structure as indicated by the 1970.03.28 (Mw= 7.2) Gediz earthquake. The graben is characterized by two distinct units, separated by an angular unconformity: (i) Miocene-middle Pliocene Arica formation and (ii) Plio Quaternary Erdogmus formation. The former unit commences with a basal conglomerate above the basement rocks and is composed mainly of coal-bearing continental and lacustrine sediments with lava flows and pyroclastics, particularly common in the middle parts of the sequence. The volcanics are dated at 18.4 &plusmn / 0.1 Ma (Ar-Ar mica ages). They record evidence for two deformation phases as suggested by twosets of overprinting slickenlines, intense folding, thrust and strike-slip faulting. The Erdogmus formation commences with terrace conglomerates and is composed mainly of travertines, older and younger alluvial deposits, fan-apron sediments and the recent axial graben floor sediments. Kinematic analysis of the graben-bounding normal faults, growth faults within the graben-infill and those deforming the sediments are consistent with three distinct phases of deformation: (i) Miocene middle Pliocene extensional phase, (ii) interveining NE SW contractional phase and (iii) Plio-Quaternary extensional phase. The data also suggests a distributed stress field and a multi-directional recent extension in predominantly NNE&ndash / SSW, E&ndash / W and NE&ndash / SW directions. This is also consistent with available focal mechanism solutions for the region. The graben therefore has an episodic evolutionary history with two extensional phases and an intervening short-term contraction, as described in many different parts of the SWAEP. The latter phase of extension is considered as the part of Neotectonic regime, which therefore commenced by the Late Pliocene.
39

Neotectonics and Paleoseismology of the Central Alpine Fault, New Zealand

De Pascale, Gregory Paul January 2014 (has links)
The Alpine Fault is a major plate boundary structure, which accommodates up to 50-80% of the total plate boundary motion across the South Island of New Zealand. The fault has not ruptured historically although limited off-fault shaking records and on-fault dating suggest large to great (~ Mw 8) earthquakes (every ~100-480 years; most recently in 1717), making it potentially one of the largest onshore sources of seismic hazard in New Zealand. The central section of the Alpine Fault, which bounds the highest elevations in the Southern Alps, is one of the most poorly characterised sections along the fault. On-fault earthquake timing in addition to the amount of dextral slip during major earthquakes was unknown along a 200-km-long section of the central Alpine Fault, while the amount of co-seismic hanging wall uplift was poorly known, prior to the present work. In this thesis I address these knowledge gaps through a combination of light detection and ranging (lidar), field, and stratigraphic mapping along with sample dating to constrain earthquake timing, style of faulting, and hanging wall rock uplift rates. Using lidar data coupled with field mapping I delineated the main trace of the Alpine Fault at Gaunt Creek as a north-striking fault scarp that was excavated and logged; this is part of a 2-km-wide restraining bend dominated by low-angle thrust faulting and without the clear strike-slip displacements that are present nearby (<5 km distant along strike in both directions). Where exposed in this scarp, the fault-zone is characterized by a distinct 5-50 cm thick clay fault-gouge layer juxtaposing hanging wall bedrock (mylonites and cataclasites) over unconsolidated late-Holocene footwall colluvium. An unfaulted peat at the base of the scarp is buried by post-most recent event (MRE) alluvium and yields a radiocarbon age of A.D. 1710–1930, consistent with sparse on-fault data, validating earlier off-fault records that suggest a 1717 MRE with a moment magnitude of Mw 8.1 ± 0.1, based on the 380-km-long surface rupture. Lidar and field mapping also enabled the identification and measurement of short (<30 m), previously unrecognized dextral offsets along the central section of the Alpine Fault. Single-event displacements of 7.5 ± 1 m for the 1717 earthquake and cumulative displacements of 12.9 ± 2 m and 22 ± 2.7 m for earlier ruptures can be binned into 7.1 ± 2.1 m increments of repeated dextral (uniform) slip along the central Alpine Fault. A comparison of these offsets with the local paleoseismic record and known plate kinematics suggests that the central Alpine Fault earthquakes in the past 1.1 ka may have: (i) bimodal character, with major surface ruptures (!Mw 7.9) every 270 ± 70 years (e.g. the 1717 event) and with moderate to large earthquakes (!Mw 7) occurring between these ruptures (e.g. the 1600 event); or (ii) that some shaking data may record earthquakes on other faults. If (i) is true, the uniform slip model (USM) perhaps best represents central Alpine Fault earthquake recurrence, and argues against the applicability of the characteristic earthquake model (CEM) there. Alternatively, if (ii) is true, perhaps the fault is “characteristic” and some shaking records proximal to plate boundary faults do not necessarily reflect plate-boundary surface ruptures. Paleoseismic and slip data suggest that (i) is the most plausible interpretation, which has implications for the understanding of major plate-boundary faults worldwide. Field mapping, geological characterisation, geophysical mapping, and optically stimulated luminescence (OSL) dating of on-fault hanging wall sediments were used to better constrain the geometry and kinematics of Holocene deformation along the rangefront of the Southern Alps at the Alpine Fault near the Whataroa River. The fault here is dextral-reverse, although primarily strike-slip with clear fault traces cutting across older surfaces of varying elevations. Deformational bulges are observed along these traces that are likely thrust-bounded. A terrace of Whataroa River sediments was found on the hanging wall of the Alpine Fault approximately ~ 55-75 m (when considering uncertainties) above the floodplain of the Whataroa River. OSL ages for a hanging wall sediments of 10.9 ± 1.0 ka for the aforementioned terrace, 2.8 ± 0.3 ka for Whataroa River terrace deposits in a deformational bulge, and 11.1 ± 1.2 ka for a rangefront derived fan indicate Holocene aggradation along the rangefront and hanging wall uplift rates of 6.0 ± 1.1 mm/yr. The sub-horizontal, laterally continuous, and planar-bedded Whataroa-sourced terrace deposits suggest that the adjacent bounding faults are steeply-dipping faults without geometries in the shallow subsurface that would tend to cause sedimentary bed rotation and tilting. Using data from the approximately 100-m deep pilot DFDP boreholes together with lidar and field mapping, I present a review of the Quaternary geology, geomorphology, and structure of the fault at Gaunt Creek, and estimate new minimum Late-Pleistocene hanging wall rock uplift rates of 5.7 ± 1.0 mm/yr to 6.3 ± 1.1 mm/yr (without considering local erosion) that suggest that the Southern Alps are in a dynamic steady state here. GPS-derived “interseismic” vertical uplift rates are < 1 mm/yr at the Alpine Fault, so the majority of rock uplift at the rangefront happens during episodic major earthquakes, confirming with on-fault data that slip occurs coseismically. Notably the uplift rates from both Mint and Gaunt Creek are consistent between the two sites although the primary style of faulting at the surface is different between the two sites, suggesting consistent coseisimc uplift of the Southern Alps rangefront along the Alpine Fault in major earthquakes. This thesis collected new on-fault datasets that confirm earlier inferences of plate-boundary fault behaviour. This study of the high-uplift central section of the Alpine Fault provides the first on-fault evidence for the MRE (i.e. 1717) and repeated of dextral slip during the MRE and previous events as well as new hanging wall uplift data which suggests that the majority of rangefront uplift occurs in earthquakes along the Alpine Fault. Because the fault has not ruptured for ~300 years, it poses a significant seismic hazard to southern New Zealand.
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Neotectonics And Evolution Of The Yenicaga Basin, Bolu - Turkey

Arca, Serkan Mehmet 01 July 2004 (has links) (PDF)
Study area, the Yeni&ccedil / aga Basin, is located in the western part of the North Anatolian Fault System. It is a 1-5-km-wide and 14-km-long WSWENE- trending depression bounded by a complex array of strike-slip faults. The Yeni&ccedil / aga Basin is interpreted to be a fault &ndash / wedge basin with the North Anatolian Fault&rsquo / s System Master Strand, namely the Gerede Fault, cutting across the basin itself. The basin and its surroundings contain mainly two groups of rock units namely the paleotectonic units and the neotectonic units. Paleotectonic units, which are deposited or formed during different phase(s) of tectonic regimes, comprise several formations. The most important one of these formations is the Upper Miocene &ndash / Lower Pliocene Eskipazar formation which plays an important role in understanding the evolutionary history of the basin. Neotectonic unit deposited under the control of today&rsquo / s tectonic regime is the Plio-Quaternary Betem&uuml / rl&uuml / formation.v Betem&uuml / rl&uuml / formation unconformably overlies the paleotectonic Eskipazar formation throughout the study area and the unconformity separating these two units corresponds to the time interval during which the paleotectonic stress regime changed into the neotectonic stress regime. Thus, onset age of the strike-slip neotectonic regime in the study area is Late Pliocene (~ 2,6 My). Common basin margin-bounding faults of the Yeni&ccedil / aga Basin are, the ASagi Kuldan fault, the Aksu fault, the izmirli fault set, the Saray&ccedil / ali fault, the Degirmen fault set and the Hamzabey fault set. They display well-preserved fault scarps in places. Morphological expressions of these faults and their geometrical relationships with the local stress regime indicate that these faults are mainly strike-slip and oblique-slip faults. Morphotectonic expressions of the faults exposing within the study area indicate that these faults are active. Most of the settlements within the study area are located on water-saturated loose basin fill nearby the active faults. Hence, these are open to future earthquake hazards. Therefore, structures and settlements have to be constructed on strong grounds away from the active faults.

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