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Sample records for active tectonic areas

  1. Hillslope development in areas of active tectonics

    NASA Astrophysics Data System (ADS)

    Arrowsmith, J. Ramón; Pollard, David D.; Rhodes, Dallas D.

    1996-03-01

    Tectonic and geomorphic displacements of the Earth's surface control topographic profile development; therefore, their analysis should be combined. In the model presented here, transient finite difference solutions to the continuity equation for material transport determine geomorphic displacements. The material transport rate is a function of distance from the divide to the power m, local slope to the power n, and a rate constant. Values of m and n may be adjusted to simulate processes varying from rainsplash and soil creep (i.e., diffusive; m = 0, n = 1) to slope wash and river flow (m > 0, n > 0). The actual geomorphic displacements may be transport or weathering-limited, depending on soil profile development. Superimposed edge dislocations in an elastic half-plane are used to model tectonic displacements. Slip along a normal or reverse fault of any dip, depth and down-dip length may be incremental (earthquake) or continuous (aseismic creep). Considering climate and material properties constant, the ratio of the transport capacity rate constant to the fault slip rate roughly determines form. This model extends existing morphologic diffusion erosion analyses to include other geomorphic conditions and processes (transport- or weathering-limited conditions, material flux boundary conditions, and the development of gullies and knickpoints) and more heterogeneous spatial and temporal distributions of tectonic displacement (such as those due to slip along buried thrust faults). We advocate calibration of these parameters and processes to provide a quantitative approach to modeling landform development, determining deformation rates, and inferring earthquake hazards.

  2. Active tectonics

    SciTech Connect

    Not Available

    1986-01-01

    This study is part of a series of Studies in Geophysics that have been undertaken for the Geophysics Research Forum by the Geophysics Study Committee. One purpose of each study is to provide assessments from the scientific community to aid policymakers in decisions on societal problems that involve geophysics. An important part of such assessments is an evaluation of the adequacy of current geophysical knowledge and the appropriateness of current research programs as a source of information required for those decisions. The study addresses our current scientific understanding of active tectonics --- particularly the patterns and rates of ongoing tectonic processes. Many of these processes cannot be described reasonably using the limited instrumental or historical records; however, most can be described adequately for practical purposes using the geologic record of the past 500,000 years. A program of fundamental research focusing especially on Quaternary tectonic geology and geomorphology, paleoseismology, neotectonics, and geodesy is recommended to better understand ongoing, active tectonic processes. This volume contains 16 papers. Individual papers are indexed separately on the Energy Database.

  3. Areas of Unsolved Problems in Caribbean Active Tectonics

    NASA Astrophysics Data System (ADS)

    Mann, P.

    2015-12-01

    I review some unsolved problems in Caribbean active tectonics. At the regional and plate scale: 1) confirm the existence of intraplate deformation zones of the central Caribbean plate that are within the margin of error of ongoing GPS measurements; 2) carry out field studies to evaluate block models versus models for distributed fault shear on the densely populated islands of Jamaica, Hispaniola, Puerto Rico, and the Virgin Islands; 3) carry out paleoseismological research of key plate boundary faults that may have accumulated large strains but have not been previously studied in detail; 4) determine the age of onset and far-field effects of the Cocos ridge and the Central America forearc sliver; 4) investigate the origin and earthquake-potential of obliquely-sheared rift basins along the northern coast of Venezuela; 5) determine the age of onset and regional active, tectonic effects of the Panama-South America collision including the continued activation of the Maracaibo block; and 6) validate longterm rates on active subduction zones with improving, tomographic maps of subducted slabs. At the individual fault scale: 1) determine the mode of termination of large and active strike -slip faults and application of the STEP model (Septentrional, Polochic, El Pilar, Bocono, Santa Marta-Bucaramanaga); 2) improve the understanding of the earthquake potential on the Enriquillo-Plantain Garden fault zone given "off-fault" events such as the 2010 Haiti earthquake; how widespread is this behavior?; and 3) estimate size of future tsunamis from studies of historic or prehistoric slump scars and mass transport deposits; what potential runups can be predicted from this information?; and 4) devise ways to keep rapidly growing, circum-Caribbean urban populations better informed and safer in the face of inevitable and future, large earthquakes.

  4. Preliminary study on hydrogeology in tectonically active areas.

    SciTech Connect

    Lowry, Thomas Stephen; Lappin, Allen R.; Gettemy, Glen L.; Jensen, Richard Pearson; Arnold, Bill Walter; James, Scott Carlton; Lee, Moo Yul; Meier, Diane A.

    2006-09-01

    This report represents the final product of a background literature review conducted for the Nuclear Waste Management Organization of Japan (NUMO) by Sandia National Laboratories, Albuquerque, New Mexico, USA. Internationally, research of hydrological and transport processes in the context of high level waste (HLW) repository performance, has been extensive. However, most of these studies have been conducted for sites that are within tectonically stable regions. Therefore, in support of NUMO's goal of selecting a site for a HLW repository, this literature review has been conducted to assess the applicability of the output from some of these studies to the geological environment in Japan. Specifically, this review consists of two main tasks. The first was to review the major documents of the main HLW repository programs around the world to identify the most important hydrologic and transport parameters and processes relevant in each of these programs. The review was to assess the relative importance of processes and measured parameters to site characterization by interpretation of existing sensitivity analyses and expert judgment in these documents. The second task was to convene a workshop to discuss the findings of Task 1 and to prioritize hydrologic and transport parameters in the context of the geology of Japan. This report details the results and conclusions of both of these Tasks.

  5. Hydrothermal fluids circulation and travertine deposition in an active tectonic setting: Insights from the Kamara geothermal area (western Anatolia, Turkey)

    NASA Astrophysics Data System (ADS)

    Brogi, Andrea; Alçiçek, M. Cihat; Yalçıner, Cahit Çağlar; Capezzuoli, Enrico; Liotta, Domenico; Meccheri, Marco; Rimondi, Valentina; Ruggieri, Giovanni; Gandin, Anna; Boschi, Chiara; Büyüksaraç, Aydin; Alçiçek, Hülya; Bülbül, Ali; Baykara, Mehmet Oruç; Shen, Chuan-Chou

    2016-06-01

    Coexistence of thermal springs, travertine deposits and tectonic activity is a recurring feature for most geothermal areas. Although such a certainty, their relationships are debated mainly addressing on the role of the tectonic activity in triggering and controlling fluids flow and travertine deposition. In this paper, we present the results of an integrated study carried out in a geothermal area located in western Anatolia (Turkey), nearby the well-known Pamukkale area (Denizli Basin). Our study focused on the relationships among hydrothermal fluids circulation, travertine deposition and tectonic activity, with particular emphasis on the role of faults in controlling fluids upwelling, thermal springs location and deposition of travertine masses. New field mapping and structural/kinematics analyses allowed us to recognize two main faults systems (NW- and NE-trending), framed in the Neogene-Quaternary extensional tectonic evolution of western Anatolia. A geo-radar (GPR) prospection was also provided in a key-area, permitting us to reconstruct a buried fault zone and its relationships with the development of a fissure-ridge travertine deposit (Kamara fissure-ridge). The integration among structural and geophysical studies, fluids inclusion, geochemical, isotopic data and 230 Th/238 U radiometric age determination on travertine deposits, depict the characteristics of the geothermal fluids and their pathway, up to the surface. Hydrological and seismological data have been also taken in account to investigate the relation between local seismicity and fluid upwelling. As a main conclusion we found strict relationships among tectonic activity, earthquakes occurrence, and variation of the physical/chemical features of the hydrothermal fluids, presently exploited at depth, or flowing out in thermal springs. In the same way, we underline the tectonic role in controlling the travertine deposition, making travertine (mainly banded travertine) a useful proxy to reconstruct the

  6. Landslides in tectonically active areas and their influence on sediment supply to basins: examples from Southern Italy

    NASA Astrophysics Data System (ADS)

    Roda-Boluda, Duna; D'Arcy, Mitch; Whittaker, Alex; McDonald, Jordan

    2016-04-01

    Landslides are a key mechanism of sediment delivery from hillslopes and can produce volumes of sediment that are potentially significant for basin stratigraphy. In tectonically active areas, landslides are highly sensitive to tectonic and lithological boundary conditions, but this sensitivity and the impact that landslides have on the overall sediment supply from catchments remain largely unquantified. Here we use a combination of DEM analysis and fieldwork to quantify the distribution and volumes of landslides along the strike of active normal faults in Southern Italy, where fault throw rates and lithology are well constrained. We then explore the geomorphic, tectonic and lithological variables controlling landslide occurrence. Additionally, we compare the landslide distribution with the transient incision that is affecting footwall channels as a result of active normal faulting. Finally, we quantify the grain size distributions (GSD) supplied by landslides across different lithologies and landslide types, and we compare them with those being supplied by bedrock weathering. Our results show that landslide frequency is highly influenced by lithology and the amount of incision experienced by the catchments, and that landslides supply on average GSDs that are 50% coarser than those supplied by the weathering of the same lithology. Landslides triggered during landscape adjustment to tectonics therefore have a significant impact both on the volumes and grain sizes of sediment exported to neighbouring basins, and the development of transient stratigraphy.

  7. Studies in geophysics: Active tectonics

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Active tectonics is defined within the study as tectonic movements that are expected to occur within a future time span of concern to society. Such movements and their associated hazards include earthquakes, volcanic eruptions, and land subsidence and emergence. The entire range of geology, geophysics, and geodesy is, to some extent, pertinent to this topic. The needs for useful forecasts of tectonic activity, so that actions may be taken to mitigate hazards, call for special attention to ongoing tectonic activity. Further progress in understanding active tectonics depends on continued research. Particularly important is improvement in the accuracy of dating techniques for recent geologic materials.

  8. Continuous monitoring of soil CO2 flux in tectonic active area of Sicily: relationship between gas emissions and crustal stress

    NASA Astrophysics Data System (ADS)

    Camarda, Marco; De Gregorio, Sofia; Favara, Rocco; Di Martino, Roberto M. R.

    2015-04-01

    Tectonic active areas are subjected to continue modification of the stress fields as result of the relative movement of portions of the crust. In these areas the stress generated the seismogenetic processes and at same time produces detectable modifications in the shallower portion of the crust such as superficial deformation, increase or decrease of pore pressure and change in fluids circulation. As results a wide variety of changes can be recorded in several parameters due to stress field modifications. The aim of this study was to monitor in continuous soil gas emissions of selected tectonic active area of the Sicily in order to investigate the relation between changes on this parameter and stress field modifications linked to seismogenetic processes. For this reason, in cooperation with DPC Sicilia a network of 20 stations for continuous monitoring of soil CO2 flux in the main seismic area of Sicily was deployed. The selection of the monitoring sites was based on a detailed geological structural study aimed to recognize active tectonic structures and on geochemical survey for identifying areas of anomalous degassing along the structures. Time series of soil CO2 flux long from 1 to 3 years were obtained. The acquired series were filtered for removing atmospheric parameters induced variations by applying the fast Fourier transform (FFT) and regression analysis.The results of comparison of filtered signals showed as almost all the stations have a low coefficient correlation, indicating that the recorded variations are likely due to minor stress modification having small spatial scale. A discrete correlation was founded between the signals of three stations placed in the same tectonic context in northeastern sector of Sicily. Interesting these stations showed a contemporary steep increase few days before the onset of seismic sequence, with events of magnitude up to 4.4, occurred in August 2013 in the northeastern Sicily. The concomitance of change in soil CO2 flux

  9. Magma-tectonic interactions in an area of active extension; a review of recent observations, models and interpretations from Iceland

    NASA Astrophysics Data System (ADS)

    Pedersen, Rikke; Sigmundsson, Freysteinn; Drouin, Vincent; Rafn Heimisson, Elías; Parks, Michelle; Dumont, Stéphanie; Árnadóttir, Þóra; Masterlark, Timothy; Ófeigsson, Benedíkt G.; Jónsdóttir, Kristín; Hooper, Andrew

    2016-04-01

    The geological setting of Iceland provides rich opportunities of studying magma-tectonic interactions, as it constitutes Earth's largest part of the mid-oceanic ridge system exposed above sea level. A series of volcanic and seismic zones accommodate the ~2 cm/year spreading between the North-American and Eurasian plates, and the Icelandic hot-spot conveniently provides the means of exposing this oceanic crust-forming setting above sea-level. Both extinct and active plumbing system structures can be studied in Iceland, as the deeply eroded tertiary areas provide views into the structures of extinct volcanic systems, and active processes can be inferred on in the many active volcanic systems. A variety of volcanic and tectonic processes cause the Icelandic crust to deform continuously, and the availability of contemporaneous measurements of crustal deformation and seismicity provide a powerful data set, when trying to obtain insight into the processes working at depth, such as magma migration through the uppermost lithosphere, magma induced host rock deformation and volcanic eruption locations and styles. The inferences geodetic and seismic datasets allow on the active plate spreading processes and subsurface magma movements in Iceland will be reviewed, in particular in relation to the Northern Volcanic Zone (NVZ). There the three phases of a rifting cycle (rifting, post-rifting, inter-rifting) have been observed. The NVZ is an extensional rift segment, bounded to the south by the Icelandic mantle plume, and to the north by the Tjörnes transform zone. The NVZ has typically been divided into five partly overlapping en-echelon fissure swarms, each with a central main volcanic production area. Most recently, additional insight into controlling factors during active rifting has been provided by the Bárðarbunga activity in 2014-2015 that included a major rifting event, the largest effusive eruption in Iceland since 1783, and a gradual caldera collapse. It is evident

  10. Active tectonics of the Atacama Basin area, northern Chile: Implications for distribution of convergence across the central Andes

    NASA Astrophysics Data System (ADS)

    Chuang, Yi-Rung; Lin, Yen-Sheng; Shyu, J. Bruce H.

    2013-04-01

    The central Andes in South America is formed as the Nazca plate subducts northeastward beneath the South American plate along the Peru-Chile trench, parallel to the coastline. It has been shown that the convergence rate between the two plates is ~70-80 mm/yr, and about 10-15 mm/yr of the convergence is absorbed in the sub-Andean belt, east of the active volcanic arc. However, the convergence in the forearc region is still not well constrained. In order to understand how much convergence is absorbed in the forearc region, we analyzed the active tectonic characteristics of the Atacama Basin, just west of the active volcanic arc. With the help of various remote sensing datasets such as 30-m and 90-m resolution digital elevation models (DEM) produced from SRTM data, thermal infrared radiometer (TIR) ASTER images, Landsat, and Google Earth images, we identified many N-S trending compressional structures around the Atacama Basin. The active structures are found mainly in the northern and southern part of the basin. The structures in the north deformed many volcanic rocks at the surface, such as ignimbrites and several lava flows. Structures may extend southward to San Pedro de Atacama, the largest town in the Atacama Basin, and produced tectonic scarps inside the town. River terraces also formed in the hanging-wall block of the structures, north of San Pedro. From field surveys, we measured the offset amount of the structures and collected volcanic rocks in order to constrain the age of the deformation. These results enabled us to calculate the long-term deformation rate of the structures. Our results indicate that the long-term slip rate of the structures in the southern part of the basin is quite low, in the order of 10-1 mm/yr. Furthermore, we obtained detailed topographic profiles across the structures. In the south, the profiles were surveyed by using real-time kinematic (RTK) GPS. Together with the attitudes of bedding planes, we constructed the subsurface geometry

  11. Late Quaternary tectonic activity and crustal shortening rate of the Bogda mountain area, eastern Tian Shan, China

    NASA Astrophysics Data System (ADS)

    Wu, Chuanyong; Wu, Guodong; Shen, Jun; Dai, Xunye; Chen, Jianbo; Song, Heping

    2016-04-01

    The Bogda mountain range is the highest range among the northern Tian Shan mountains. Based on geologic and geomorphologic field surveys, trench excavation and optically stimulated luminescence (OSL) dating, we targeted the active Fukang fault along the Bogda mountain range and identified the late Quaternary deformation characteristics of this area. We found that the Fukang fault dislocated different geomorphic surfaces of the northern Bogda piedmont. The vertical fault displacement corresponds to the topographic relief of the Bogda over long time scales. Since the late Quaternary, the crustal shortening rate was estimated to be 0.90 ± 0.20 mm/yr, which is less than that of the western segment of the northern Tian Shan. We interpret the Bogda fold and thrust belt to be a thick-skinned structure, since a high angle thrust fault bounds the Bogda mountain range and the foreland basin. The deformation characteristics of this region have been dominated by vertical uplift, and the component of propagation toward the basin has been very limited. This tectonic deformation is evidenced as vertical growth. Although the deformation rate is small, the uplift amplitude is very significant in this region.

  12. Sediment Yields Revealed and Fluid Modelling by Twice LiDAR Surveys in Active Tectonics Area

    NASA Astrophysics Data System (ADS)

    Hsieh, Y.; Chan, Y.; Hu, J.; Lin, C.

    2010-12-01

    LiDAR technique allows rapid acquisition of high resolution and high precision topographic data. The technique has found considerable use in the earth sciences, for example for fluvial morphology and flood modelling. These developments have offered new opportunities for investigating spatial and temporal patterns of morphological change in gravel-bed river and have contributed to develop in two points: (1)morphometric estimates of sediment transport and sediment yields ;(2)boundary conditions for numerical models, including computational fluid dynamics and modelling. This topographic research funded by the Taiwan Central Geological Survey, surveyed the terrain of the Lanyang River before and after the typhoon season using Airborne LiDAR technique, and computed the terrain variations. The Lanyang River is one of main rivers in Taiwan and often suffers the influence of typhoon during summer. Most of sediments generated from slump and soil erosion into river were transported from the upstream watershed and resulted in the riverbed changes during the typhoon season. In 2008, there are four significant typhoon events influencing this area, including the Kalmaegi, Fung-wong, Sinlaku, and Jangmi typhoons. At present, sediment yield calculation often used empirical or theoretical formula as well as data collected at hydrological stations, and rarely had the actual measured value through high-resolution topography. The variations of the terrain on the riverbed may be regarded as the sediment yield of the bed load transported during the typhoon season. This research used high-resolution terrain models to compute sediment yield of the bed load, and further discussed volumes of sediment yield in watershed during the typhoon season. In the Lanyang River we discovered that the upstream and midstream channel still had the characteristics of erosion and transportation during the typhoon season. The results imply significant sediment yield and transportation from the upstream

  13. Active tectonic influence on the evolution of drainage and landscape: Geomorphic signatures from frontal and hinterland areas along the Northwestern Himalaya, India

    NASA Astrophysics Data System (ADS)

    Malik, Javed N.; Mohanty, C.

    2007-03-01

    The Kangra Re-entrant in the NW Himalaya is one of the most seismically active regions, falling into Seismic Zone V along the Himalaya. In 1905 the area experienced one of the great Himalayan earthquakes with magnitude 7.8. The frontal fault system - the Himalayan Frontal Thrust (HFT) associated with the foreland fold - Janauri Anticline, along with other major as well as secondary hinterland thrust faults, provides an ideal site to study the ongoing tectonic activity which has influenced the evolution of drainage and landscape in the region. The present study suggests that the flat-uplifted surface in the central portion of the Janauri Anticline represents the paleo-exit of the Sutlej River. It is suggested that initially when the tectonic activity propagated southward along the HFT the Janauri Anticline grew along two separate fault segments (north and south faults), the gap between these two fault and the related folds allowed the Sutlej River to flow across this area. Later, the radial propagation of the faults towards each other resulted in an interaction of the fault tips, which caused the rapid uplift of the area. Rapid uplift resulted in the disruption and longitudinal deflection of the Sutlej river channel. Fluvial deposits on the flat surface suggest that an earlier fluvial system flowed across this area in the recent past. Geomorphic signatures, like the sharp mountain fronts along the HFT in some places, as well as along various hinterland subordinate faults like the Nalagarh Thrust (NaT), the Barsar Thrust (BaT) and the Jawalamukhi Thrust (JMT); the change in the channel pattern, marked by a tight incised meander of the Beas channel upstream of the JMT indicate active tectonic movements in the area. The prominent V-shaped valleys of the Beas and Sutlej rivers, flowing across the thrust fronts, with Vf values ranging from <1.0-1.5 are also suggestive of ongoing tectonic activity along major and hinterland faults. This suggests that not only is the HFT

  14. Impact of wind erosion on detecting active tectonics from geomorphic indexes in extremely arid areas: a case study from the Hero Range, Qaidam Basin, NW China

    NASA Astrophysics Data System (ADS)

    Wu, Lei; Xiao, Ancheng; Yang, Shufeng

    2014-11-01

    Geomorphologic analysis has been used widely to detect active tectonics in regions where fluvial incision is the major erosional process. In this paper, however, we assess the feasibility of utilizing these frequently-used geomorphic indexes (e.g., hypsometric curves, longitudinal channel profiles, normalized stream length-gradient (SLK) index) to determine active tectonics in extremely arid areas where wind erosion also plays an important role. The case study is developed on the Hero Range in the western Qaidam Basin, one of the driest regions on Earth with severe wind erosion since late Pliocene. The result shows that in the west and south sectors, as well as the western part of the east sector, of the Hero Range where fluvial incision prevails, these geomorphic indexes are good indicators of active faulting and consistent with the geological result based on study of fault traces, scarps, faulted Holocene fans and historical seismicity within the past four decades. In contrast, along the northeastern margin (the NE and the SE parts of the east sector) of the range where wind erosion is also important, the results from the geomorphic indexes show quite active tectonics, contrary with the geological evidence favoring weakly active tectonics. Moreover, the positive SLK anomaly lies oblique to the fault trace and the anticline axis but parallel to the wind direction. To reconcile the contradiction, we propose that wind erosion caused by northwestern winds has a tendency to make geomorphic indexes exhibit anomalous values that indicate higher activities, by way of (1) lowering the base-level to generate knickpoints on the longitudinal channel profiles and therefore positive SLK anomalies, and (2) lateral erosion of the mountain front making the hypsometric curves and even the longitudinal channel profiles more convex, and producing obvious slope breaks.

  15. Active faulting Vs other surface displacing complex geomorphic phenomena. Case studies from a tectonically active area, Abruzzi Region, central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Lo Sardo, Lorenzo; Gori, Stefano; Falcucci, Emanuela; Saroli, Michele; Moro, Marco; Galadini, Fabrizio; Lancia, Michele; Fubelli, Giandomenico; Pezzo, Giuseppe

    2016-04-01

    How can be univocally inferred the genesis of a linear surface scarp as the result of an active and capable fault (FAC) in tectonically active regions? Or, conversely, how it is possible to exclude that a scarp is the result of a capable fault activation? Trying to unravel this open questions, we show two ambiguous case studies about the problem of the identification of active and capable faults in a tectonically active area just based on the presence of supposed fault scarps at surface. The selected cases are located in the area comprised between the Middle Aterno Valley Fault (MAVF) and the Campo Imperatore Plain (Abruzzi Region, central Apennines), nearby the epicentral area of the April 6th, 2009 L'Aquila earthquake. In particular, the two case studies analysed are located in a region characterized by a widespread Quaternary faults and by several linear scarps: the case studies of (i) Prata D'Ansidonia area and (ii) Santo Stefano di Sessanio area. To assess the origin and the state of activity of the investigated geomorphic features, we applied a classical geological and geomorphological approach, based on the analysis of the available literature, the interpretation of the aerial photographs, field surveying and classical paleoseismological approach, the latter consisting in digging excavations across the analysed scarps. These analysis were then integrated by morphometrical analyses. As for case (i), we focused on determining the geomorphic "meaning" of linear scarps carved onto fluvial-deltaic conglomerates (dated to the Early Pleistocene; Bertini and Bosi, 1993), up to 3 meters high and up to 1,5 km long, that border a narrow, elongated and flat-bottom depressions, filled by colluvial deposits. These features groove the paleo-landsurface of Valle Daria (Bosi and Bertini, 1970), wide landsurface located between Barisciano and Prata D'Ansidonia. Entwining paleoseismological trenching with geophysical analyses (GPR, ERT and microgravimetrical prospections), it

  16. Active tectonic features and structural dynamics of the summit area of Mt. Etna (Italy) revealed by soil CO2 and soil temperature surveying

    NASA Astrophysics Data System (ADS)

    Giammanco, Salvatore; Melián, Gladys; Neri, Marco; Hernández, Pedro A.; Sortino, Francesco; Barrancos, José; López, Manuela; Pecoraino, Giovannella; Perez, Nemesio M.

    2016-02-01

    This work presents the results of an extensive geochemical survey aimed at measuring soil CO2 effluxes and soil temperatures over a large portion of Mt. Etna's summit area, coupled with an updated structural survey of the same area. The main goals of this study were i) to find concealed or hidden volcano-tectonic structures in the studied area by detecting anomalous soil gas emissions, ii) to investigate the origin of the emitted gas and the mechanism of gas and heat transport to the surface, iii) to produce a structural model based both on the surface geology and on the soil gas data and, lastly, iv) to contribute to the assessment of hazard from slope failure and crater collapses at Mt. Etna. The results revealed many concealed structural lines that followed the major directions of structural weakness in the summit area of Mt. Etna, mostly due to a combined action of gravitational spreading of the volcano and magma intrusions. Both recent and old volcano-tectonic lines were found to act as pathways for the leakage of magmatic gases to the surface. An important role in driving magmatic gases to the surface is also played by fracturing and faulting due to caldera-forming collapses and smaller crater collapses. Correlation between soil CO2 emissions and soil temperature allowed discriminating areas of active shallow hydrothermal circulation along deep fractures (characterized by high values of both parameters, but mostly soil temperature) from those affected by undeveloped fractures that did not reach the surface (characterized by high CO2 emissions at low temperature). The former corresponded to weak zones of the volcano edifice that were frequently site of past eruptions, indicating that those areas keep a high potential for future opening of eruptive fissures. The latter were likely related to sites where new eruptive fissures may open in the near future due to backward propagation of extensional tectonic stress.

  17. Active faulting Vs other surface displacing complex geomorphic phenomena. Case studies from a tectonically active area, Abruzzi Region, central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Lo Sardo, Lorenzo; Gori, Stefano; Falcucci, Emanuela; Saroli, Michele; Moro, Marco; Galadini, Fabrizio; Lancia, Michele; Fubelli, Giandomenico; Pezzo, Giuseppe

    2016-04-01

    How can be univocally inferred the genesis of a linear surface scarp as the result of an active and capable fault (FAC) in tectonically active regions? Or, conversely, how it is possible to exclude that a scarp is the result of a capable fault activation? Trying to unravel this open questions, we show two ambiguous case studies about the problem of the identification of active and capable faults in a tectonically active area just based on the presence of supposed fault scarps at surface. The selected cases are located in the area comprised between the Middle Aterno Valley Fault (MAVF) and the Campo Imperatore Plain (Abruzzi Region, central Apennines), nearby the epicentral area of the April 6th, 2009 L'Aquila earthquake. In particular, the two case studies analysed are located in a region characterized by a widespread Quaternary faults and by several linear scarps: the case studies of (i) Prata D'Ansidonia area and (ii) Santo Stefano di Sessanio area. To assess the origin and the state of activity of the investigated geomorphic features, we applied a classical geological and geomorphological approach, based on the analysis of the available literature, the interpretation of the aerial photographs, field surveying and classical paleoseismological approach, the latter consisting in digging excavations across the analysed scarps. These analysis were then integrated by morphometrical analyses. As for case (i), we focused on determining the geomorphic "meaning" of linear scarps carved onto fluvial-deltaic conglomerates (dated to the Early Pleistocene; Bertini and Bosi, 1993), up to 3 meters high and up to 1,5 km long, that border a narrow, elongated and flat-bottom depressions, filled by colluvial deposits. These features groove the paleo-landsurface of Valle Daria (Bosi and Bertini, 1970), wide landsurface located between Barisciano and Prata D'Ansidonia. Entwining paleoseismological trenching with geophysical analyses (GPR, ERT and microgravimetrical prospections), it

  18. Active tectonics of the Andes

    NASA Astrophysics Data System (ADS)

    Dewey, J. F.; Lamb, S. H.

    1992-04-01

    Nearly 90 mm a -1 of relative plate convergence is absorbed in the Andean plate-boundary zone. The pattern of active tectonics shows remarkable variations in the way in which the plate slip vector is partitioned into displacement and strain and the ways in which compatibility between different segments is solved. Along any traverse across the plate-boundary zone, the sum of relative velocities between points must equal the relative plate motion. We have developed a kinematic synthesis of displacement and strain partitioning in the Andes from 47°S to 5°N relevant for the last 5 Ma based upon: (1) relative plate motion deduced from oceanic circuits giving a roughly constant azimuth between 075 and 080; (2) moment tensor solutions for over 120 crustal earthquakes since 1960; (3) structural studies of deformed Plio-Pleistocene rocks; (4) topographic/geomorphic studies; (5) palaeomagnetic data; and (6) geodetic data. We recognize four neotectonic zones, with subzones and boundary transfer zones, that are partitioned in different ways. These zones are not coincident with the 'classic' zones defined by the presence or absence of a volcanic chain or differences in finite displacements and strains and tectonic form; the long-term segmentation and finite evolution of the Andes may not occur in constantly defined segments in space and time. In Segment 1 (47°-39°S), the slip vector is partitioned into roughly orthogonal Benioff Zone slip with large magnitude/large slip-surface earthquakes and both distributed dextral shear giving clockwise rotations of up to 50° and dextral slip in the curved Liquine-Ofqui Fault System giving 5°-10° of anticlockwise fore-arc rotation. In Segment 2 (39°-20°S), the slip vector is partitioned into Benioff Zone slip roughly parallel with the slip vector, Andean crustal shortening and a very small component of dextral slip, including that on the Atacama Fault System. Between 39° and 34°S, a cross-strike dextral transfer, which deflects

  19. Inversion tectonics in the Maracaibo area, Venezuela

    SciTech Connect

    Roberta, M. ); Duval, B.; Cramez, C.

    1993-02-01

    Sequence stratigraphy and structural interpretation of regional composite seismic lines and new 3D seismic data of Lake Maracaibo lead us to question the old [open quotes]strike-slip fault movement[close quotes] geological paradigm as the major cause of deformation in this area. The pre-Miocene compressional structures of the majority of the oil fields of this area such as Ceuta, Lama, Motatan, etc., are easily and better explained as the result of a Tertiary Tectonic Inversion. Such inversion can be interpreted as a consequence of shortening of [open quotes]depocenters[close quotes] (grabens and half grabens) developed during extensional phases of a back-arc basin. During this shortening, the old faults bordering the [open quotes]depocenters[close quotes] were reactivated with reverse movements creating large compressional structural traps in the hanging wall (old downthrown block). Thin-skinned compressional deformation can occur, locally, outside the major [open quotes]depocenters[close quotes] in the footwall areas between faults of opposite vergence.

  20. Physico-chemical evolution of groundwater in tectonically active areas. Application to the Leana hot spring (Murcia Region, SE Spain)

    NASA Astrophysics Data System (ADS)

    Martínez, M.; Hornero, J.; Trujillo, C.

    2016-09-01

    Seismic events can affect the physico-chemical characteristics of groundwater. These anomalies are of a pre-seismic, co-seismic and post-seismic nature and correspond to pulse variations, sudden increases and decreases without return to initial values and upward or downward changes in trend. Continuous and in situ conductivity and temperature monitoring and periodic water sampling at a hot spring associated with neotectonic activity are of great interest for establishing predictive methods. This method is limited to the seismic activity affecting the fracturing system with which the hot spring is associated. The Region of Murcia and surroundings (southeast Spain) was selected as the study area for exploring the nature of these influences on groundwater. A hot spring in the Leana spa (Murcia) was equipped and monitored during the period 2006-2008, allowing for the in situ determination of conductivity and temperature as well as of major and minor constituents at the laboratory. Due to its proximity and related with fault network, we suggest that 86 % of earthquakes located between 0 and 10 km may affect in situ parameters of groundwater, and 75 % may affect laboratory determinations. This percentage drops in more distant zones. Of all earthquakes that seem to influence groundwater, 55 % of the in situ parameter anomalies and 53 % of laboratory were of a pre-seismic nature.

  1. A global tectonic activity map with orbital photographic supplement

    NASA Technical Reports Server (NTRS)

    Lowman, P. D., Jr.

    1981-01-01

    A three part map showing equatorial and polar regions was compiled showing tectonic and volcanic activity of the past one million years, including the present. Features shown include actively spreading ridges, spreading rates, major active faults, subduction zones, well defined plates, and volcanic areas active within the past one million years. Activity within this period was inferred from seismicity (instrumental and historic), physiography, and published literature. The tectonic activity map was used for planning global geodetic programs of satellite laser ranging and very long base line interferometry and for geologic education.

  2. Global tectonic activity map with orbital photographic supplement

    SciTech Connect

    Lowman, P.D. Jr.

    1981-01-01

    A three part map showing equatorial and polar regions was compiled showing tectonic and volcanic activity of the past one million years, including the present. Features shown include actively spreading ridges, spreading rates, major active faults, subduction zones, well defined plates, and volcanic areas active within the past one million years. Activity within this period was inferred from seismicity (instrumental and historic), physiography, and published literature. The tectonic activity map was used for planning global geodetic programs of satellite laser ranging and very long base line interferometry and for geologic education.

  3. Active tectonics and human survival strategies

    NASA Astrophysics Data System (ADS)

    King, Geoffrey; Bailey, Geoffrey; Sturdy, Derek

    1994-10-01

    Tectonic movements continuously remould the surface of Earth in response to plate motion. Yet such deformation is rarely taken into account when assessing landscape change and its impact on human land use, except perhaps as an occasional hazard to human life or a temporary disruption in the longer term patterns of human history. However, active tectonics also create and sustain landscapes that can be beneficial to human survival, forming a complex topography of potentially fertile sedimentary basins enclosed by mountain barriers that can facilitate the control and explotation of food resources, especially animal prey. We discuss the tectonic history of northwest Greece and show how the Paleolithic sites of the region are located to take advantage of tectonically created features at both a local and a regional scale. We suggest that the association of significant concentrations of early Paleolithic sites with tectonically acitve regions is not coincidental and that on the longer time spans of human biological evolution, active tectonics has been an important selective agent contributing to the development of the human species as an intelligent predator.

  4. Deep electrical resistivity tomography along the tectonically active Middle Aterno Valley (2009 L'Aquila earthquake area, central Italy)

    NASA Astrophysics Data System (ADS)

    Pucci, Stefano; Civico, Riccardo; Villani, Fabio; Ricci, Tullio; Delcher, Eric; Finizola, Anthony; Sapia, Vincenzo; De Martini, Paolo Marco; Pantosti, Daniela; Barde-Cabusson, Stéphanie; Brothelande, Elodie; Gusset, Rachel; Mezon, Cécile; Orefice, Simone; Peltier, Aline; Poret, Matthieu; Torres, Liliana; Suski, Barbara

    2016-11-01

    Three 2-D Deep Electrical Resistivity Tomography (ERT) transects, up to 6.36 km long, were obtained across the Paganica-San Demetrio Basin, bounded by the 2009 L'Aquila Mw 6.1 normal-faulting earthquake causative fault (central Italy). The investigations allowed defining for the first time the shallow subsurface basin structure. The resistivity images, and their geological interpretation, show a dissected Mesozoic-Tertiary substratum buried under continental infill of mainly Quaternary age due to the long-term activity of the Paganica-San Demetrio normal faults system (PSDFS), ruling the most recent deformational phase. Our results indicate that the basin bottom deepens up to 600 m moving to the south, with the continental infill largely exceeding the known thickness of the Quaternary sequence. The causes of this increasing thickness can be: (1) the onset of the continental deposition in the southern sector took place before the Quaternary, (2) there was an early stage of the basin development driven by different fault systems that produced a depocentre in the southern sector not related to the present-day basin shape, or (3) the fault system slip rate in the southern sector was faster than in the northern sector. We were able to gain sights into the long-term PSDFS behaviour and evolution, by comparing throw rates at different timescales and discriminating the splays that lead deformation. Some fault splays exhibit large cumulative throws (>300 m) in coincidence with large displacement of the continental deposits sequence (>100 m), thus testifying a general persistence in time of their activity as leading splays of the fault system. We evaluate the long-term (3-2.5 Myr) cumulative and Quaternary throw rates of most of the leading splays to be 0.08-0.17 mm yr-1, indicating a substantial stability of the faults activity. Among them, an individual leading fault splay extends from Paganica to San Demetrio ne' Vestini as a result of a post-Early Pleistocene linkage of

  5. Late Tertiary paleogeographic and tectonic evolution of the Mediterranean area

    SciTech Connect

    Arnott, R.J.; Haan, E.A.

    1988-08-01

    The present geography of the Mediterranean Sea is the result of late Tertiary tectonic processes and hardly reflects its Mesozoic and early Tertiary evolution. This paper outlines a plate tectonics model for the Mediterranean area from the Oligocene to the Pliocene. Seismic and well data have been integrated into the regional structural framework to produce a set of paleogeographic maps, which includes the Oligocene, early and middle Miocene, late Miocene, and Pliocene. These maps highlight the changes in sedimentation patterns in response to the tectonic development of the Mediterranean area. Special attention will be given to the Messinian desiccation event.

  6. Integrated multi-parameters Probabilistic Seismic Landslide Hazard Analysis (PSLHA): an innovative approach in the active volcano-tectonic area of Campi Flegrei (Italy)

    NASA Astrophysics Data System (ADS)

    Caccavale, M.; Matano, F.; Sacchi, M.; Somma, R.; Troise, C.; De Natale, G.

    2013-12-01

    The western coastal sector of Campania region (southern Italy) is characterised by the presence of the active volcano-tectonic area of Campi Flegrei. This area represents a very particular and interesting case-study for a probabilistic seismic hazard analysis (PSHA). The principal seismic source, related with the caldera, is not clearly constrained in the on-shore and off-shore areas. The well-known and monitored phenomenon of bradyseism affecting a large portion of case-study area is not modelled in the standard PSHA approach. From the environmental point of view the presence of very high exposed values in terms of population, buildings, infrastructures and palaces of high archaeological, natural and artistic value, makes this area a strategic natural laboratory to develop new methodologies. Moreover the geomorphological and geo-volcanological features lead to a heterogeneous coastline, made up by both beach and tuff cliffs, rapidly evolving for erosion and landslide (i.e. mainly rock fall and rock slide) phenomena that represent an additional hazard aspect. In the Campi Flegrei the possible occurrence of a moderate/large seismic event represents a serious threat for the inhabitants, for the infrastructures as well as for the environment. In the framework of Italian MON.I.C.A project (sinfrastructural coastlines monitoring) an innovative and dedicated probabilistic methodology has been applied to identify the areas with higher tendency of landslide occurrence due to the seismic effect. Resident population reported the occurrence of some small rock falls along tuff quarry slopes during the main shocks of the 1982-84 bradyseismic events. The PSHA methodology, introduced by Cornell (1968), combines the contributions to the hazard from all potential sources of earthquakes and the average activity rates associated to each seismogenic zone considered. The result of the PSHA is represented by the spatial distribution of a ground-motion (GM) parameter A, such as Peak

  7. Geomorphic Indices in the Assessment of Tectonic Activity in Forearc of the Active Mexican Subduction Zone

    NASA Astrophysics Data System (ADS)

    Gaidzik, K.; Ramirez-Herrera, M. T.

    2015-12-01

    Rapid development of GIS techniques and constant advancement of digital elevation models significantly improved the accuracy of extraction of information on active tectonics from landscape features. Numerous attempts were made to quantitatively evaluate recent tectonic activity using GIS and DEMs, and a set of geomorphic indices (GI), however these studies focused mainly on sub-basins or small-scale areal units. In forearc regions where crustal deformation is usually large-scale and do not concentrate only along one specific fault, an assessment of the complete basin is more accurate. We present here the first attempt to implement thirteen GI in the assessment of active tectonics of a forearc region of an active convergent margin using the entire river basins. The GIs were divided into groups: BTAI - basin geomorphic indices (reflecting areal erosion vs. tectonics) and STAI - stream geomorphic indices (reflecting vertical erosion vs. tectonics). We calculated selected indices for 9 large (> 450 km2) drainage basins. Then we categorized the obtained results of each index into three classes of relative tectonic activity: 1 - high, 2 - moderate, and 3 - low. Finally we averaged these classes for each basin to determine the tectonic activity level (TAI). The analysis for the case study area, the Guerrero sector at the Mexican subduction zone, revealed high tectonic activity in this area, particularly in its central and, to a lesser degree, eastern part. This pattern agrees with and is supported by interpretation of satellite images and DEM, and field observations. The results proved that the proposed approach indeed allows identification and recognition of areas witnessing recent tectonic deformation. Moreover, our results indicated that, even though no large earthquake has been recorded in this sector for more than 100 years, the area is highly active and may represent a seismic hazard for the region.

  8. Exploring Active Tectonics in the Dominican Republic

    NASA Astrophysics Data System (ADS)

    Carbó-Gorosabel, A.; Córdoba-Barba, D.; Martín-Dívila, J.; Granja-Bruña, J. L.; Llanes Estrada, P.; Muñoz-Martín, A.; ten Brink, U. S.

    2010-07-01

    The devastating 12 January 2010 Haiti earthquake (M = 7.0), which killed an estimated 230,000 people and caused extensive damage to homes and buildings, drew attention to the crucial need for improved knowledge of the active tectonics of the Caribbean region. But even before this disastrous event, interest in understanding the active and complex northeastern Caribbean plate boundary had been increasing, because this region has experienced significant seismic activity during the past century and has an extensively documented record of historical seismicity and tsunamis. Moreover, this is an easily accessible region in which to study the continuity of seismic faults offshore and to try to understand the transitions between strike-slip and convergent tectonic regimes. Interest in the region has led to several studies that have improved scientists' knowledge of subduction zone tectonics and earthquake and tsunami hazard assessments 005BMann et al., 2002; ten Brink et al., 2006, 2009; Grindlay et al., 2005; Manaker et al., 2008; Granja Bruña et al., 2009; Mondziel et al., 2010].

  9. Ground subsidence and associated ground fracturing in urban areas: InSAR monitoring of active tectonic structures (Ciudad Guzman, Colima Graben - Mexico)

    NASA Astrophysics Data System (ADS)

    Bignami, C.; Brunori, C.; Zucca, F.; Groppelli, G.; Norini, G.; Hernandez, N. D.; Stramondo, S.

    2013-12-01

    This study focuses on the observation of a creeping phenomenon that produces subsidence of the Zapotlan basin and ground fracturing in correspondence of the Ciudad Guzmàn (Jalisco - Mexico). The September 21, 2012, the Ciudad Guzmàn has been struck by a phenomenon of ground fracturing of about 1.5 km of length. This event caused the deformation of the roads and the damage of 30 houses, of which eight have been declared uninhabitable. The alignment of fractures is coincident with the escarpments produced in September 19, 1985, in the Ciudad Guzman urban area, when a strong earthquake, magnitude 8.1, struck the Mexican area, causing the deaths of at least 10,000 people and serious damage in Mexico City. In Ciudad Guzmán, about 60% of the buildings were destroyed, with about 50 loss of life. The city is located in the Zapotlan basin (northern Colima graben), a wide tectonic depression where the depth of the infilling sediments is about 1 km. This subsidence cannot be measured outside the urbanized area, but it can be considered as a deformation mechanism of the central part of the basin. In order to detect and mapping the spatio-temporal features of the processes that led to this event, we applied InSAR multi-temporal techniques to analyze a dataset of ENVISAT satellite SAR images, acquired in a time span between 2003-2010. InSAR techniques detect a subsidence of the north-western part of Ciudad Guzmàn of about 15 mm/yr in the time interval 2003-2010. The displacement occurred in September 21, 2012, was detected using two RadarSAT2 acquisitions (2012-03-22 and 2013-03-17). The explanation of surface movements based on interferometric results, ground data and geological field observations, allowed confirming surface effect due to the overexploitation of the aquifers and highlights a subsidence due to anthropogenic causes coupled to buried tectonic structures.

  10. Upper plate responses to active spreading ridge/transform subduction: The tectonics, basin evolution, and seismicity of the Taita area, Chile Triple Junction

    SciTech Connect

    Flint, S.; Prior, D. ); Styles, P.; Murdie, R. ); Agar, S.; Turner, P. )

    1993-02-01

    Integrated field geophysical, structural and stratigraphic studies are attempting to elucidate the mechanisms and consequences of the Late Miocene-present day subduction of the Chile Ridge triple junction system. Preliminary data indicate a shallow plane of seismicity at about 15 km to 20 km depth below the Taitao peninsula. The depths correspond to the predicted depth range of subducted upper ocean crust. The calculated Bouguer anomaly map cannot be explained by the upper plate geology, suggesting that gravity is influenced by heterogeneities in the subducting oceanic plate. Seismic data imply that a subducted transform system underlying the inner Taitao Peninsula is still an active structure. A series of Middle-Late Tertiary sedimentary basins lie inboard of the triple junction. Within the Cosmelli basin, abrupt marine to continental facies transitions give clear evidence of base level changes. The amount of basinward shift of facies across sequence boundaries gets progressively greater up stratigraphy, indicating progressively greater base level changes. The lower part of the basin fill is folded and then thrusted eastward as a series of imbricates, while the overlying, greater thickness of fluvial sediments are only gently tilted westwards. We provisionally interpret this geometry to indicate that the early basin fill was deforming due to contractional tectonics while the later basin fill was being deposited. This complex basin history may reflect initiation and development of triple junction subduction.

  11. The tectonic puzzle of the Messina area (Southern Italy): Insights from new seismic reflection data

    PubMed Central

    Doglioni, Carlo; Ligi, Marco; Scrocca, Davide; Bigi, Sabina; Bortoluzzi, Giovanni; Carminati, Eugenio; Cuffaro, Marco; D'Oriano, Filippo; Forleo, Vittoria; Muccini, Filippo; Riguzzi, Federica

    2012-01-01

    The Messina Strait, that separates peninsular Italy from Sicily, is one of the most seismically active areas of the Mediterranean. The structure and seismotectonic setting of the region are poorly understood, although the area is highly populated and important infrastructures are planned there. New seismic reflection data have identified a number of faults, as well as a crustal scale NE-trending anticline few km north of the strait. These features are interpreted as due to active right-lateral transpression along the north-eastern Sicilian offshore, coexisting with extensional and right-lateral transtensional tectonics in the southern Messina Strait. This complex tectonic network appears to be controlled by independent and overlapping tectonic settings, due to the presence of a diffuse transfer zone between the SE-ward retreating Calabria subduction zone relative to slab advance in the western Sicilian side. PMID:23240075

  12. A Digital Tectonic Activity Map of the Earth

    NASA Technical Reports Server (NTRS)

    Lowman, Paul; Masuoka, Penny; Montgomery, Brian; OLeary, Jay; Salisbury, Demetra; Yates, Jacob

    1999-01-01

    The subject of neotectonics, covering the structures and structural activity of the last 5 million years (i.e., post-Miocene) is a well-recognized field, including "active tectonics," focussed on the last 500,000 years in a 1986 National Research Council report of that title. However, there is a cartographic gap between tectonic maps, generally showing all features regardless of age, and maps of current seismic or volcanic activity. We have compiled a map intended to bridge this gap, using modern data bases and computer-aided cartographic techniques. The maps presented here are conceptually descended from an earlier map showing tectonic and volcanic activity of the last one million years. Drawn by hand with the National Geographic Society's 1975 "The Physical World" map as a base, the 1981 map in various revisions has been widely reproduced in textbooks and various technical publications. However, two decades of progress call for a completely new map that can take advantage of new knowledge and cartographic techniques. The digital tectonic activity map (DTM), presented in shaded relief (Fig. 1) and schematic (Fig. 2) versions, is the result. The DTM is intended to show tectonism and volcanism of the last one million years, a period long enough to be representative of global activity, but short enough that features such as fault scarps and volcanos are still geomorphically recognizable. Data Sources and Cartographic Methods The DTM is based on a wide range of sources, summarized in Table 1. The most important is the digital elevation model, used to construct a shaded relief map. The bathymetry is largely from satellite altimetry, specifically the marine gravity compilations by Smith and Sandwell (1996). The shaded relief map was designed to match the new National Geographic Society world physical map (1992), although drawn independently, from the digital elevation model. The Robinson Projection is used instead of the earlier Van der Grinten one. Although neither

  13. Tectonics

    NASA Astrophysics Data System (ADS)

    John Dewey will complete his term as editor-in-chief of Tectonics at the end of 1984. Clark Burchfiel's term as North American Editor will also end. Tectonics is published jointly with the European Geophysical Society. This newest of AGU's journals has already established itself as an important journal bridging the concerns of geophysics and geology.James A. Van Allen, president of AGU, has appointed a committee to recommend candidates for both editor-in-chief and North American editor for the 1985-1987 term.

  14. Relief Evolution in Tectonically Active Mountain Ranges

    NASA Technical Reports Server (NTRS)

    Whipple, Kelin X.

    2004-01-01

    The overall aims of this 3-yr project, as originally proposed were to: (1) investigate quantitatively the roles of fluvial and glacial erosion in the evolution of relief in mountainous regions, and (2) test rigorously the quality and accuracy of SRTM topographic data in areas of rugged relief - both the most challenging and of greatest interest to geomorphic, neotectonic, and hazards applications. Natural laboratories in both the western US and the Southern Alps of New Zealand were identified as most promising. The project has been both successful and productive, despite the fact that no SRTM data for our primary field sites in New Zealand were released on the time frame of the work effort. Given the delayed release of SRTM data, we pursued the scientific questions of the roles of fluvial and, especially, glacial erosion in the evolution of relief in mountainous regions using available digital elevation models (DEMs) for the Southern Alps of New Zealand (available at both 25m and 50m pixel sizes), and USGS 10m and 30m DEMs within the Western US. As emphasized in the original proposal, we chose the emphasis on the role of glacial modification of topographic relief because there has been little quantitative investigation of glacial erosion processes at landscape scale. This is particularly surprising considering the dramatic sculpting of most mid- and high-latitude mountain ranges, the prodigious quantities of glacially-derived sediment in terrestrial and marine basins, and the current cross-disciplinary interest in the role of denudational processes in orogenesis and the evolution of topography in general. Moreover, the evolution of glaciated landscapes is not only a fundamental problem in geomorphology in its own right, but also is at the heart of the debate over Late Cenozoic linkages between climate and tectonics.

  15. Active Tectonics in crossroads of an evolving orogen and morphological consequences: Anatolia

    NASA Astrophysics Data System (ADS)

    Koral, Hayrettin

    2016-04-01

    Anatolia lies in a curved setting of the active Alpine Mountain Range and is located in crossroads of the European and Asian terrains. It is one of the fastest deforming land in the world, manifested by seismicity, characteristic landforms and GPS measurements. Active tectonics in Anatolia provides not only a comparable geological model for the past orogens, but also a laboratory case for morphological consequences of an orogenic processes. Anatolia comprise different tectonic subsettings with its own characteristics. Northern part is influenced by tectonic characteristics of the Black Sea Basin, the Pontides and the Caucasian Range; northwestern part by the Balkanides; eastern-southeastern part by the Bitlis-Zagros suture; and south-southwestern part by the eastern Mediterranean subduction setting. Much of its present tectonic complexity was inherited from the convergence dominant plate tectonic setting of the platelets prior to the Middle-Neogene. Beginning about 11 Ma ago, the deformed and uplifted landmass unable to accommodate further deformation in Anatolia and ongoing tectonic activity gave rise to rearrangement of tectonic forces and westerly translational movements. Formation of major strike-slip faults in Anatolia including the North and East Anatolian Faults and a new platelet called the Anatolian Plate are the consequences of this episode. Such change in the tectonic regime has led to modification of previously-formed landscape, modification and sometimes termination of previously-formed basins. Evidence is present in the Plio-Quaternary stratigraphy, tectonic characteristics and morphology of the well-studied areas. This presentation will discuss active tectonic features of the northwestern, southwestern and eastern Anatolian subsettings and their influence on morphology that is closely related to sites of pre-historical human settlement.

  16. Overview of geology and tectonic evolution of the Baikal-Tuva area.

    PubMed

    Gladkochub, Dmitry; Donskaya, Tatiana

    2009-01-01

    This chapter provides the results of geological investigations of the main tectonic units of the Baikal-Tuva region (southwestern part of Siberia) during the last decades: the ancient Siberian craton and adjacent areas of the Central Asian Orogenic belt. In the framework of these main units we describe small-scale blocks (terranes) with focus on details of their inner structure and evolution through time. As well as describing the geology and tectonics of the area studied, we give an overview of underwater sediments, neotectonics, and some phenomena of history and development of the Baikal, Khubsugul, Chargytai, and Tore-Chol Lakes basins of the Baikal-Tuva region. It is suggested that these lakes' evolution was controlled by neotectonic processes, modern seismic activity, and global climate changes.

  17. Tectonic control on the drainage system in a piedmont region in tectonically active eastern Himalayas

    NASA Astrophysics Data System (ADS)

    Goswami, Chandreyee; Mukhopadhyay, Dhruba; Poddar, Bikash Chandra

    2012-03-01

    The impact of neotectonic activity on drainage system has been studied in a large alluvial fan in the eastern Himalayan piedmont area between the Mal River and the Murti River. Two distinct E-Wlineaments passing through this area had been identified by Nakata (1972, 1989) as active faults. The northern lineament manifested as Matiali scarp and the southern one manifested as Chalsa scarp represent the ramp anticlines over two blind faults, probably the Main Boundary Thrust (MBT) and the Himalayan Frontal Thrust (HFT), respectively. The fan surface is folded into two antiforms with a synform in between. These folds are interpreted as fault propagation folds over the two north dipping blind thrusts. Two lineaments trending NNE-SSW and nearly N-S, respectively, are identified, and parts of present day courses of the Murti and Neora Rivers follow them. These lineaments are named as Murti and Neora lineaments and are interpreted to represent a conjugate set of normal faults. The rivers have changed their courses by the influence of these normal faults along the Murti and Neora lineaments and their profiles show knick points where they cross E-W thrusts. The overall drainage pattern is changed from radial pattern in north of the Matiali scarp to a subparallel one in south due to these conjugate normal faults. The interfluve area between these two rivers is uplifted as a result of vertical movements on the above mentioned faults. Four major terraces and some minor terraces are present along the major river valleys and these are formed due to episodic upliftment of the ground and subsequent down-cutting of the rivers. The uppermost terrace shows a northerly slope north of the Chalsa scarp as a result of folding mentioned above. But rivers on this terrace form incised channels keeping their flow southerly suggesting that they are antecedent to the folding and their downcutting kept pace with the tectonism.

  18. Active Tectonics And Modern Geodynamics Of Sub-Yerevan Region

    NASA Astrophysics Data System (ADS)

    Avanesyan, M.

    2004-05-01

    The given work is dedicated to active tectonics and modern geodynamics of Sub-Yerevan region. This region is interesting as a one of regions with maximal seismic activity in Armenia. The high level of seismic risk of this region is conditioned by high level of seismic hazard, high density of the population, as well as presence of objects of special importance and industrial capacities. The modern structure of Sub-Yerevan region and the adjacent area, as well as the Caucasus entirely, has mosaic-block appearance, typical for collision zone of Arabian and Eurasian plates. Distinctively oriented active faults of various ranges and morphological types are distinguished. These faults, in their turn, form various-scale active blocks of the Earth's crust and their movement defines seismic activity of the region. The researches show, that all strong earthquakes in the region were caused by movements by newest and activated ancient faults. In order to reveal the character of Earth's crust active blocks movement, separation of high gradients of horizontal and vertical movements and definition of stress fields highest concentration regions by GPS observations, high-accuracy leveling and study of earthquake focal mechanisms a new seismotectonic model is developed, which represents a combination of tectonic structure, seismic data, newest and modern movements. On the basis of comparison and analysis of these data zones with potential maximal seismic hazard are separated. The zone of joint of Azat-Sevan active and Yerevan abysmal faults is the most active on the territory of Sub-Yerevan region. The directions relatively the Earth's crust movement in the zones of horizontal and vertical movement gradients lead to conclusion, that Aragats-Tsakhkunian and Gegam active blocks undergo clockwise rotation. This means, that additional concentration of stress must be observed in block corners, that is confirmed by location of strong earthquakes sources. Thus, on the North 1988 Spitak (M

  19. Tectonic and sedimentary evolution of the Luna field area, Italy

    SciTech Connect

    Roveri, M. )

    1990-05-01

    The Luna gas field is located near Crotone (Calabria region, southern Italy) in a shallow-water/onshore area. It was discovered and put into production during the early 1970s. Up to now it has produced 19 {times} 10{sup 9} sm{sup 3} of gas; its productivity (50 {times} 10{sup 6} sm{sup 3}/y) has remained virtually unaltered since the beginning. The field is located on the axial culmination of a thrust-related anticline of the Apennine postcollisional thrust belt; it can be roughly subdivided into two areas characterized by different stratigraphic contexts. In the northern and central parts of the field is a structural trap. Reservoir rocks are Serravallian to Tortonian deep marine resedimented conglomerates and sandstones. These deposits represent part of the infill of a middle-upper Miocene foredeep. Reservoir rocks are now thrusted, eroded, and unconformably overlain by lower Pliocene shales, which are the most important seal in this part of the field. In the southern part of the field is a combination trap. Reservoir rocks are upper Tortonian shallow-water sandstones. They lap onto a Tortonian unconformity related to a tectonic phase which split the previous foredeep into minor piggyback basins. The upper Tortonian sandstones are overlain and sealed by Messinian shales and evaporites. Tectonosedimentary evolution of the area and, consequently, areal distribution and geometry of sedimentary bodies - both potential reservoirs and seals - have been reconstructed using a sequence stratigraphy approach. The sedimentary record has been informally subdivided into five main depositional sequences bounded by unconformities or their correlative conformities; classic facies analysis and petrophysical, seismic, and biostratigraphic data have been utilized to define the internal characteristics of each sequence.

  20. The Current Tectonics of the Yukon and Adjacent Area

    NASA Astrophysics Data System (ADS)

    Hyndman, R. D.; Leonard, L. J.

    2014-12-01

    The current tectonics across the Yukon and adjacent areas of western Northwest Territories (NWT) and northern British Columbia appear to be driven primarily by the Yakutat Terrane collision, an "indenter" in the corner of the Gulf of Alaska. GPS data show 1-10 mm/yr northward and eastward, decreasing inland. The rates from earthquake statistics are similar although there are important discrepancies. The eastern Cordillera earthquake mechanisms are mainly thrust in the Mackenzie Mountains of southwestern NWT where the Cordillera upper crust is overthrusting the craton. To the north, the mechanisms are mainly strike-slip in the Richardson Mountains that appear to lie along the edge of the craton. The deformation appears to be limited to the hot and weak Cordillera with the strong craton providing an irregular eastern boundary. For example, there is an eastward bow in the craton edge and the deformation in the Mackenzie Mountains. On the Beaufort Sea margin in the region of the Mackenzie Delta there appears to be a type of "subduction zone" with the continent very slowly overthrusting the oceanic plate, a process that has continued since at least the Cretaceous. A northward moving continental margin block is bounded by left lateral faulting in the west (Canning Displacement Zone of eastern Alaska) and right lateral faulting in the east (Richardson Mountains in eastern Yukon). There is almost no seismicity on this thrust belt but as for some other subduction zones such as Cascadia there is the potential for very infrequent great earthquakes.

  1. Hydrothermal and tectonic activity in northern Yellowstone Lake, Wyoming

    USGS Publications Warehouse

    Johnson, S.Y.; Stephenson, W.J.; Morgan, L.A.; Shanks, Wayne C.; Pierce, K.L.

    2003-01-01

    Yellowstone National Park is the site of one of the world's largest calderas. The abundance of geothermal and tectonic activity in and around the caldera, including historic uplift and subsidence, makes it necessary to understand active geologic processes and their associated hazards. To that end, we here use an extensive grid of high-resolution seismic reflection profiles (???450 km) to document hydrothermal and tectonic features and deposits in northern Yellowstone Lake. Sublacustrine geothermal features in northern Yellowstone Lake include two of the largest known hydrothermal explosion craters, Mary Bay and Elliott's. Mary Bay explosion breccia is distributed uniformly around the crater, whereas Elliott's crater breccia has an asymmetric distribution and forms a distinctive, ???2-km-long, hummocky lobe on the lake floor. Hydrothermal vents and low-relief domes are abundant on the lake floor; their greatest abundance is in and near explosion craters and along linear fissures. Domed areas on the lake floor that are relatively unbreached (by vents) are considered the most likely sites of future large hydrothermal explosions. Four submerged shoreline terraces along the margins of northern Yellowstone Lake add to the Holocene record or postglacial lake-level fluctuations attributed to "heavy breathing" of the Yellowstone magma reservoir and associated geothermal system. The Lake Hotel fault cuts through northwestern Yellowstone Lake and represents part of a 25-km-long distributed extensional deformation zone. Three postglacial ruptures indicate a slip rate of ???0.27 to 0.34 mm/yr. The largest (3.0 m slip) and most recent event occurred in the past ???2100 yr. Although high heat flow in the crust limits the rupture area of this fault zone, future earthquakes of magnitude ???5.3 to 6.5 are possible. Earthquakes and hydrothermal explosions have probably triggered landslides, common features around the lake margins. Few high-resolution seismic reflection surveys have

  2. Lineaments on Ganymede: New evidence for late tectonic activity

    NASA Astrophysics Data System (ADS)

    Croft, S. K.

    1985-04-01

    Families of lineaments in the Gilomesh and Ninki basins of Ganymede imply post impact tectonic activity. The grooves, previously considered the youngest tectonic features, are estimated to have formed between 3.8 and 3.1 Gyr ago. One rayed crater however, is probably less than 1 Gyr old, implying tectonic activity on Ganymede has extended nearly to the present. Like the grooves, the lineaments appear to be extensional. The parallel trends and nearly contiguous associations of the lineaments with the grooves imply that both are products of the same stress systems. The young inferred age of the lineaments implies that they (and presumably also the grooves) are not associated with stresses in the cooling of fresh deposits of bright terrain, but are probably associated with underlying convective stress patterns, the long implied duration of an extensional stress regime in Ganymede's lithosphere is consistent with the stress models of derived assuming a differentiated interior.

  3. Lineaments on Ganymede: New Evidence for Late Tectonic Activity

    NASA Technical Reports Server (NTRS)

    Croft, S. K.

    1985-01-01

    Families of lineaments in the Gilomesh and Ninki basins of Ganymede imply post impact tectonic activity. The grooves, previously considered the youngest tectonic features, are estimated to have formed between 3.8 and 3.1 Gyr ago. One rayed crater however, is probably less than 1 Gyr old, implying tectonic activity on Ganymede has extended nearly to the present. Like the grooves, the lineaments appear to be extensional. The parallel trends and nearly contiguous associations of the lineaments with the grooves imply that both are products of the same stress systems. The young inferred age of the lineaments implies that they (and presumably also the grooves) are not associated with stresses in the cooling of fresh deposits of bright terrain, but are probably associated with underlying convective stress patterns, the long implied duration of an extensional stress regime in Ganymede's lithosphere is consistent with the stress models of derived assuming a differentiated interior.

  4. Regional tectonics of Myanmar (Burma) and adjacent areas

    SciTech Connect

    Everett, J.R.; Russell, O.R.; Staskowski, R.J.; Loyd, S.P.; Tabbutt, V.M. ); Dolan, Stein, A. )

    1990-05-01

    Analysis of 38 contiguous Landsat Multispectral Scanner scenes acquired over Myanmar (Burma) reveals numerous large-scale features associated with margins of the Burman plate, previously unidentified northeast-southwest-trending discontinuities, important extensions of previously mapped fault trends, and numerous structural features that appear favorable for petroleum exploration. A mosaic of these scenes at 1:1,000,000 scale shows a large number of tectonic elements and their spatial relationships. Within the area of investigation are portions of the Indian, Burman, Lhasa, and Shan-Thai plates, and perhaps other, smaller plates. The Himalayan front and Indo-Burman Ranges manifest effects of current and recently past plate movement. The complexity of the kinematic history accounts for the diversity of structural features in the area. The last major event in this long and violent saga, which began in middle Miocene (approximately 11 Ma) time and continues to the present, is the recent change from a collisional to a right-lateral strike-slip transform margin between the Indian and Burman plates. The complexity of the structures visible is the product of multiple plate collisions, rotation of the Indian plate and parts of the Asian plate, and long-continued convergence that changed velocity and direction tbrough time. The most obvious evidence of this complexity, which is immediately apparent on geologic maps or the Landsat mosaic of the region, is the almost right-angle relationship of the folds of the Indo-Burman Ranges and the frontal thrusts and suture zones of the Himalaya. These two sets of compressive features imply maximum compressive stress axes that lie at right angles to each other. The implications are either that the orientation of the stress field changes rapidly over a short distance or that the stress field has changed through time. Both occurrences seem to be true.

  5. Glacial reorganization of topography in a tectonically active mountain range

    NASA Astrophysics Data System (ADS)

    Adams, Byron; Ehlers, Todd

    2016-04-01

    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns, and not tectonic rock uplift rates. Alpine glaciers drastically altered the relief structure of the Olympic Mountains. The details of these relief changes are recorded in channel profiles as overdeepenings, reduced slopes, and associated knickpoints. We find the position of these relief changes within the orogen is dependent on the position of the Pleistocene ELA. While alpine glaciers overdeepened valleys in regions near the Pleistocene ELA (which has a tendency to increase relief), headward erosion of west and north flowing glacier systems captured significant area from opposing systems and caused drainage divide lowering. This divide lowering reduced relief throughout the range. We demonstrate similar topographic effects recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on

  6. Areas of Active Tectonic Uplift Are Sensitive to Small Changes in Fold Orientations within a Broad Zone of Left-lateral Transpression and Shearing, Dominican Republic and Haiti (Hispaniola)

    NASA Astrophysics Data System (ADS)

    Ambrosius, I.; Mann, P.

    2014-12-01

    Previous GPS studies have shown that the island of Hispaniola is a 250 km-wide zone of active, east-west, left-lateral shearing along two major strike-slip zones: the Septentrional-Oriente fault zone through the northern part of the island and the Enriquillo-Plantain Garden fault zone (EPGFZ) through the southern part of the island. The total interplate rate distributed on both faults is 21 mm/yr. Using a high-resolution DEM, we constructed fluvial channel profiles across transpression-related folds of late Miocene to recent age in the area of central and southern Dominican Republic and Haiti to determine controls of areas of relatively high, moderate, and slow uplift inferred from fluvial channel profiles. Fold axes in this area extend for 50-150 km and exhibit two different trends: 1) folds that occupy the area of the Sierra de Neiba-Chaine des Matheux north of the Enriquillo-Cul-de-Sac Valley and EPGFZ and folds that occupy the area of the Sierra de Bahoruco-Massif de la Selle all exhibit more east-west fold axes trending 110; 2) folds that occupy the area northwest of the EPGFZ in the western Chaine des Matheux and Sierra de Neiba all exhibit fold axes with more northwest trends of 125. River channel profiles show that the second group of more northwesterly-trending fold axes show relatively higher rates of tectonic uplift based on their convex-upward river profiles. Our interpretation for regional variations in river profiles and inferred uplift is that uplift is more pronounced on fold axes trending 15 degrees more to the northwest because their axes are more oblique to the interplate direction of east-west shearing. Longterm uplift rates previously measured from a stairstep of late Quaternary coral terraces at the plunging nose of the westernmost Chaine des Matheux have been previously shown to be occurring at a rate of 0.19 mm/yr. Onland exposures of Holocene corals are found only on one locality within the southern area of folds 30 km west of the epicenter

  7. Morphological expression of active tectonics in the Southern Alps

    NASA Astrophysics Data System (ADS)

    Robl, Jörg; Heberer, Bianca; Neubauer, Franz; Hergarten, Stefan

    2015-04-01

    rates are not well constrained for the entire domain. Despite of that, extensive karstification in some areas limits the validity of a morphometric analysis in particular of the upper reaches of the drainage system and leads to a long term persistence of landforms (e.g. plateaus). In this study we focus on the drainage pattern of the eastern Southern Alps and the adjacent southern foreland basin. We use a high-resolution digital elevation model and a novel numerical approach to extract characteristic parameters of the morphology for the entire eastern Southern Alps with a high spatial resolution. We explore deviations in the steepness of channels from an equilibrium state and knick-points in longitudinal channel profiles and interpret these features in terms of (a) active tectonics, and variable uplift rates, (b) lithological effects like erodibility contrasts and karstification, and (c) base level lowering caused by glacial erosion and Messinian preconditioning. The drainage system of the Adige shows the most significant deviations from a fluvial equilibrium. This is documented in the normalized steepness index of the main channel and all tributaries as well as in the longitudinal channel profile. The main channel shows several sections of downstream steepening and extremely low channel gradients in the lower reach. Similar deviations are also observed in the Brenta catchment situated east of the Adige drainage system. In contrast to the two large western catchments of the study region, the Piave and particularly the Tagliamento catchment show well graded channel profiles and uniform normalized steepness indices despite of the glacial history. This clear west to east trend from highly disturbed to overall well graded channels has never been documented before and may be explained in the light of increased uplift rates in the east and differences in onset and timing of topography formation between the western and eastern sector of the study region.

  8. Lithosphere-asthenosphere Structure and Active Tectonics In Central Italy

    NASA Astrophysics Data System (ADS)

    Chimera, G.; Aoudia, A.; Saraò, A.; Panza, G. F.

    We investigate the lithosphere-asthenosphere structure and the active tectonics along a stripe from the Tyrrhenian to the Adriatic with emphasis on the Umbria-Marche area by means of surface-wave tomography, and inversion studies for structure and seismic moment tensor retrieval. The data include seismic waveforms, a large compilation of local group velocities (0.8-4s) and regional phase and group velocity (10-100s) measurements. The local group velocity maps cover the area reactivated by the 1997 Umbria-Marche earthquake sequence. These maps suggest a relation between the lat- eral heterogeneity and distribution of the active faults and related basins. Such relation is confirmed by the non-linear inversion of the local dispersion curves. To image the deeper structure from the Tyrrhenian to the Adriatic coast, we fix the uppermost part of the crust using the Umbria-Marche models along with the CROP03 profile and related shear wave velocity, and invert the additional long period dispersion measure- ments. The results of the inversion show the geometry and lateral heterogeneity of the lithosphere-asthenosphere system. The retrieved models for the Umbria-Marche up- per crust reveal the importance of the inherited compression on the ongoing extension and related seismic activity. The reactivated 1997 normal fault zone displays a thrust fault geometry as evidenced by the lateral extent of the faulted Late Triassic evap- orites that did not yet balance the cumulative normal faulting deformation attesting therefore recent extensional tectonics within the thrust belt. Our data are in favor of a listric geometry of faulting at depth. Source inversion studies of the two main crustal events of September 26 and October 14, 1997 show the dominance of normal faulting mechanisms, whereas selected aftershocks between the reactivated fault segments re- veal that the prevailing deformation at the step-over is of strike-slip faulting type. The rupture of the three distinct and

  9. Ancient Tectonic and Volcanic Activity in the Tharsis Region

    NASA Astrophysics Data System (ADS)

    Werner, S. C.; Kronberg, P.; Hauber, E.; Grott, M.; Steinberger, B.; Torsvik, T. H.; Neukum, G.

    The two topographically dominating volcanic provinces on Mars are the Tharsis and the Elysium regions, situated close to the equator on the dichotomy boundary between the heavily cratered (older) highlands and the northern lowlands (about 100 degrees apart). The regions are characterized by volcanoes whose morphologies are analogous to volcanic landforms on Earth, and the huge volcanoes in the Tharsis region (Olympus Mons and Tharsis Montes) are prime examples resembling many characteristics of Hawaiian shield volcanoes. The main difference between the Martian and terrestrial volcanoes are their size and the length of the flows, possibly due to higher eruption rates, the "stationary" character of the source (no plate tectonics) and the lower gravity. The Tharsis plateau is the topographically most prominent region on Mars, and associated with an areoid high. On Earth, large geoid highs are related to longlived heterogeneities near the core-mantle boundary that are sources for large igneous provinces. The Tharsis' volcanic vent structures were active at least episodically over the past 4 billion years (based on crater count statistics), which indicates long-lived volcanic and magmatic activity. Two major groups of tectonic features are related to the Tharsis bulge: a concentric set of wrinkle ridges indicating compression radial to Tharsis,and several sets of extensional structures that radiate outward from different centers within Tharsis, indicating tension circumferential to Tharsis. No landforms imply ancient plate tectonics. Here, we present surface ages associated with volcanic and tectonic landforms with a special focus on the ancient magma-tectonic environment (see Grott et al. 2006, this volume). We will examine the long-lived volcanism and tectonic surface expressions and discuss whether Mars volcanism could represent deep mantle plumes.

  10. Copernican tectonic activities in the northwestern Imbrium region of the Moon

    NASA Astrophysics Data System (ADS)

    Daket, Yuko; Yamaji, Atsushi; Sato, Katsushi

    2015-04-01

    Mare ridges and lobate scarps are the manifestations of horizontal compression in the shallow part of the Moon. Conventionally, tectonism within mascon basins has been thought to originate from mascon loading which is syndepositional tectonics (e.g., Solomon and Head, 1980). However, Ono et al. (2009) have pointed out that the subsurface tectonic structures beneath some mare ridges in Serenitatis appeared to be formed after the deposition of mare strata. Watters et al. (2010) also reported Copernican lobate scarps. Those young deformations cannot be explained by the mascon loading and are possibly ascribed to global cooling, orbital evolution and/or regional factors. Since mare ridges are topographically larger than lobate scarps, they might have large contribution to the recent contraction. In this study, we estimated until when the tectonic activities of mare ridges lasted in the northwestern Imbrium region. In order to infer the timing of the latest ages of tectonic activities, we used craters dislocated by the thrust faults that run along to the mare ridges in the study area. The ages of dislocated craters indicate the oldest estimate of the latest tectonic activity of the faults, because those craters must have existed during the tectonic activities. The ages of craters are inferred by the degradation levels classified by Trask (1971). We found ~450 dislocated craters in the study area. About 40 of them are smaller than 100 meter in diameter. Sub-hundred-meter-sized craters that still maintain their morphology sharp are classified into Copernican Period. Those small dislocated craters are interspersed all over the region, indicating that the most of the mare ridges in the study area were tectonically active in Copernican Period. In addition, we also found two sub-hundred-meter-sized craters dislocated by a graben at the west of Promontorium Laplace, indicating horizontal extension existed at Copernican Period. Consequently, tectonic activities in the study

  11. Tectonic significance of Neoproterozoic magmatism of Nakora area, Malani igneous suite, Western Rajasthan, India

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Vallinayagam, G.

    2014-05-01

    Three magmatic phases are distinguished in the Neoproterozoic Nakora Ring Complex (NRC) of Malani Igneous Suite (MIS), namely (a) Extrusive (b) Intrusive and (c) Dyke phase. Magmatism at NRC initiated with minor amount of (basic) basalt flows and followed by the extensive/voluminous acid (rhyolites-trachytes) flows. The ripple marks are observed at the Dadawari area of NRC in tuffaceous rhyolite flow which suggests the aqueous condition of flows deposition. The emplacement of the magma appears to have been controlled by a well defined NE-SW tectonic lineament and cut by radial pattern of dykes. These NE-SW tectonic lineaments are the linear zones of crustal weakness and high heat flow. The spheroidal and rapakivi structures in the Nakora acid volcanics indicate the relationship between genetic link and magma mixing. Basalt-trachyte-rhyolite association suggests that the large amount of heat is supplied to the crust from the magma chamber before the eruption. The field (elliptical/ring structures), mineralogical and geochemical characteristics of Nakora granites attest an alkaline character in their evolution and consistent with within plate tectonic setting. The emplacement of these granites and associated volcanics is controlled by ring structures, a manifestation of plume activity and cauldron subsidence, an evidence of extensional tectonic environment. NRC granites are the product of partial melting of rocks similar to banded gneiss from Kolar Schist Belt of India. The present investigations suggest that the magmatic suites of NRC rocks are derived from a crustal source and the required heat supplied from a mantle plume.

  12. Active tectonics coupled to fluvial erosion in the NW Himalaya

    NASA Astrophysics Data System (ADS)

    Vannay, J.-C.; Grasemann, B.; Rahn, M.; Frank, W.; Carter, A.

    2003-04-01

    Both syntaxial extremities of the Himalaya show a spatial correlation between active exhumation of deep crustal rocks and the presence of powerful rivers, the Indus and the Tsangpo-Brahmaputra, cutting across the range two of the deepest gorges on Earth. These features strongly suggests that vigorous fluvial erosion can locally enhance isostatic and tectonic uplift, which in turn contributes to heat advection and weakening of the crust, as well as to maintain steep topographic gradients [Zeitler et al., 2001]. In order to test this positive feedback model, we combined structural and geochronological data to constrain the tectono-thermal evolution along the Sutlej (NW India), the third largest river cross-cutting entirely the Himalaya. The Himalayan crystalline core zone exposed along the Sutlej Valley is composed of two gneiss sheets, that were successively underthrusted and tectonically extruded as a consequence of the foreland-directed propagation of deformation in the Indian plate margin. During Early to Middle Miocene, combined thrusting along the Main Central Thrust (MCT) and extension along the Sangla Detachment induced the rapid exhumation and cooling of the amphibolite facies to migmatitic High Himalayan Crystalline Sequence [Vannay &Grasemann, 2001]. Underthrusting beneath the MCT led to the creation of the amphibolite facies Lesser Himalayan Crystalline Sequence (LHCS). The LHCS cooled rapidly from Late Miocene to Pleistocene, as a consequence of tectonic extrusion controlled by thrusting along the Munsiari Thrust, and extension in the MCT hanging wall. This phase is still active, as indicated by: (1) cooling rates in excess of 100^oC/Myr during the past ˜3 Myr in the LHCS; (2) Holocene neo-tectonic activity; (3) present-day hydrothermal activity testifying to elevated near-surface geothermal gradients; and (4) seismic activity along the Munsiari Thrust. Modelling of fluvial erosion in the Himalaya indicate that the Sutlej Valley corresponds to the main

  13. The seismicity of Ethiopia; active plate tectonics

    USGS Publications Warehouse

    Mohr, P.

    1981-01-01

    Ethiopia, descended from the semimythical Kingdom of Punt, lies at the strategic intersection of Schmidt's jigsaw puzzle where the Red Sea, Gulf of Aden, and the African Rift System meet. Because of geologically recent uplift combined with rapid downcutting erosion by rivers, notably the Blue Nile (Abbay), Ethiopia is the most mountainous country in Africa. It is also the most volcanically active, while its historical seismicity matches that of the midocean ridges. And, in a sense, Ethiopia is host to an evoloving ocean ridge system. 

  14. Active tectonic studies in the United States, 1987-1990

    SciTech Connect

    Weldon, R.J., II )

    1991-01-01

    The techniques and instrumentation used in active tectonic studies are discussed, and recent results are reviewed. It is suggested that a critical mass of data on several particular regions has been accumulated, making possible critical debates and attempts to assess earthquake hazards. Particular attention is given to studies of the Pacific Northwest region, basin and range deformation studies, and distributed deformation and hidden earthquake sources. Also included is a comprehensive bibliography for the period.

  15. Northeast Basin and Range province active tectonics: An alternative view

    SciTech Connect

    Westaway, R. )

    1989-09-01

    Slip rates and slip vector azimuths on major active oblique normal faults are used to investigate whether circulation associated with the Yellowstone upwelling plume is driving tectonic deformation in the northeast Basin and Range province. Observed deformation is consistent with this suggestion; the plume is sheared to the southwest by motion of the North American plate. Testable predictions are made for structure and evolution of the region.

  16. Assessment of relative tectonic activity in the Trichonis Lake graben (Western Greece) using geomorphometry

    NASA Astrophysics Data System (ADS)

    Karymbalis, Efthimios; Valkanou, Kanella; Fubelli, Giandomenico; Ferentinou, Maria; Giles, Philip; Papanastassiou, Dimitris; Gaki-Papanastassiou, Kalliopi; Tsanakas, Konstantinos

    2016-04-01

    In tectonically active areas fluvial systems and mountain fronts are controlled by the type, geometry, and recent activity of faults. The aim of this study is to investigate the contribution of neotectonics to the development of the fluvial landscape of the broader Trichonis Lake area (located in western continental Greece) through quantitative geomorphological analysis. The Trichonis Lake graben is a well-known tectonic depression of Quaternary age, which cuts across the early Tertiary NW-SE fold and thrust structures of the Pindos Mountain belt. It strikes WNW-ESE for a distance of 32 km and has a width of 10 km. The graben at the north and south flanks of the lake is bounded by E-W and NW-SE trending faults. Recent seismic activity (a shallow earthquake sequence in 1975 and a 2007 earthquake swarm) showed the existence of a NNW-SSE normal fault that dips to the NE and bounds the south-eastern shore of the lake. The studied catchments are developed on the hanging walls of these active normal faults. To evaluate the relative tectonic activity in the study area, various morphometric indices were measured for 35 catchments (slope of the valley sides of the catchment, hypsometric integral, catchment asymmetry factor, relief ratio, Melton's ruggedness number, stream-gradient index, ratio of valley floor width to valley height, and catchment shape) and 20 mountain fronts (mountain-front sinuosity index) around the lake. For the measurement of the geomorphometric variables a digital elevation model (DEM) with 2-m spatial resolution was derived from topographic maps at 1:5000 scale with 4-m contour lines, and a series of maps showing the spatial distribution of the variables were produced in a GIS environment. For each morphometric variable the catchments were classified into three classes. The combination of these morphometric variables allowed us to yield two new indices of relative tectonic activity (named IRTA - Index of Relative Tectonic Activity and IAT - Index of

  17. Active tectonics and earthquake potential of the Myanmar region

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Sieh, Kerry; Tun, Soe Thura; Lai, Kuang-Yin; Myint, Than

    2014-04-01

    This paper describes geomorphologic evidence for the principal neotectonic features of Myanmar and its immediate surroundings. We combine this evidence with published structural, geodetic, and seismic data to present an overview of the active tectonic architecture of the region and its seismic potential. Three tectonic systems accommodate oblique collision of the Indian plate with Southeast Asia and extrusion of Asian territory around the eastern syntaxis of the Himalayan mountain range. Subduction and collision associated with the Sunda megathrust beneath and within the Indoburman range and Naga Hills accommodate most of the shortening across the transpressional plate boundary. The Sagaing fault system is the predominant locus of dextral motion associated with the northward translation of India. Left-lateral faults of the northern Shan Plateau, northern Laos, Thailand, and southern China facilitate extrusion of rocks around the eastern syntaxis of the Himalaya. All of these systems have produced major earthquakes within recorded history and continue to present major seismic hazards in the region.

  18. Landscape response to recent tectonic deformation in the SW Pannonian Basin: Evidence from DEM-based morphometric analysis of the Bilogora Mt. area, NE Croatia

    NASA Astrophysics Data System (ADS)

    Matoš, Bojan; Pérez-Peña, José Vicente; Tomljenović, Bruno

    2016-06-01

    Bilogora Mt. area is a transpressional structure located in the NE of Croatia, linked with the tectonic evolution of the Drava Depression. The structure formed during Pliocene and Quaternary from the inversion of NW-striking Drava Depression Boundary Fault, which originated as a normal fault and was reactivated as a dextral strike-slip fault. During Pliocene and Quaternary time, Bilogora Mt. area underwent more than 400 m of differential uplift, while still ongoing tectonic deformation is documented by historical and instrumental seismicity (3.5 ≤ ML ≤ 5.6). In this geomorphic study, the recent deformation in the Bilogora Mt. area, although obscured by landscape evolution variables, was assessed using DEM-based landscape morphometry and a set of morphometric indexes. Local relief and slope angle variability distributions were combined with morphometric indexes computed at the scale of the drainage basin. We analyzed hypsometric curves with the hypsometric integral (HI), basin asymmetry (AF) and parameters of longitudinal stream profiles (Cf, Cmax, Δl/L, θ, and ksn). Analyzed morphometric parameters were combined into a cumulative index of relative tectonic activity (RTA). This index summarizes drainage basin response to the possible recent tectonic activity. Results suggest that most of the tectonic activity is probably located along the NE front of the Bilogora Mt. area, in its NW and central part. This activity could be likely related to recent tectonic activity along the Kalnik Mt. Fault zone and Drava Depression Boundary Fault zones, respectively. A subordinate area characterized by recent tectonic activity could be suggested within the southernmost part of the study area. Quaternary activity in this area is probably related to NE-striking faults in vicinity of the town Daruvar that continue towards the northeast into the study area. Though methodology presented here represents a good identification tool of possible ongoing deformation, this study will be

  19. Geomorphic signatures of active tectonics in the Trans-Yamuna segment of the western Doon valley, northwest Himalaya, India

    NASA Astrophysics Data System (ADS)

    Philip, George; Sah, Madho P.

    Being involved in the late orogenic movements of the sub-Himalaya, the Doon valley and its Quaternary formations have received considerable attention from Earth scientists in the study of active tectonics and paleoseismic events. Study of aerial photographs and satellite data, and selected field checks not only confirmed neotectonic features already reported by various authors but also revealed the presence of more such features. In response to active tectonics, these features have affected very young terraces and Quaternary sediments in the Trans-Yamuna segment of the Doon valley in the western sub-Himalaya. In the present study, an attempt has been made to understand the neotectonic implications of these movements on landforms in and around Sataun-Sirmuri Tal. Ground evidence indicates that the area has experienced at least three major tectonic impulses since the generation of the Main Boundary Thrust. The major tectonic disturbances are most likely due to co-seismic activity along the ongoing Himalayan tectonic processes. In this paper, we discuss some of the strong geomorphic signatures, such as lineament and active fault traces, pressure ridges, sag ponds, alluvial fans, river terraces and finally landslides, which are indicative of active tectonics in this area. On the basis of the present-day geomorphic configuration of this sub-Himalayan basin, a possible evolutionary history is also presented.

  20. Active Tectonics: Part 2: Epeirogenic and intraplate movements

    NASA Astrophysics Data System (ADS)

    Brown, L. D.; Reilinger, R. E.

    The major deformations of the Earth's surface are largely consistent with the tenets of plate tectonics, which predict that such activity should be focused at the various boundaries along which massive lithospheric plates collide, pull apart, or slide past one another. Yet crustal deformations also occur well into the interior of these plates. Some may represent the distributed effects of distant plate boundaries, as, for example, the earthquakes of the intermontane western United States. Some, such as the geodetically observed uplift over a deep magma chamber in the Rio Grande rift of New Mexico, may correspond to incipient foundation of a new plate boundary. Others, like the subtle, broad uplifts and subsidences in the nominally stable cratonic interiors, are much more puzzling. Such motions often appear estranged, if not divorced, from accepted plate-tectonic processes. Postglacial rebound, a well-known phenomenon in portions of North America and Europe, also appears to be an inadequate explanation for many observations. Understanding contemporary motions of plate interiors is often hindered by the paucity and uncertain accuracy of relevant geophysical and geodetic observations. Yet intraplate tectonics constitutes more than a scientific enigma. Even seemingly slow vertical motions may threaten river courses or seafront properties on socially relevant time scales, and the subtle strain accumulating elsewhere may portend future earthquakes or volcanoes in the least predictable places.

  1. Tectonic activity and the evolution of submarine canyons: The Cook Strait Canyon system, New Zealand

    NASA Astrophysics Data System (ADS)

    Micallef, Aaron; Mountjoy, Joshu; Barnes, Philip; Canals, Miquel; Lastras, Galderic

    2016-04-01

    Submarine canyons are Earth's most dramatic erosional features, comprising steep-walled valleys that originate in the continental shelf and slope. They play a key role in the evolution of continental margins by transferring sediments into deep water settings and are considered important biodiversity hotspots, pathways for nutrients and pollutants, and analogues of hydrocarbon reservoirs. Although comprising only one third of continental margins worldwide, active margins host more than half of global submarine canyons. We still lack of thorough understanding of the coupling between active tectonics and submarine canyon processes, which is necessary to improve the modelling of canyon evolution in active margins and derive tectonic information from canyon morphology. The objectives of this study are to: (i) understand how tectonic activity influences submarine canyon morphology, processes, and evolution in an active margin, and (2) formulate a generalised model of canyon development in response to tectonic forcing based on morphometric parameters. We fulfil these objectives by analysing high resolution geophysical data and imagery from Cook Strait Canyon system, offshore New Zealand. Using these data, we demonstrate that tectonic activity, in the form of major faults and structurally-generated tectonic ridges, leaves a clear topographic signature on submarine canyon location and morphology, in particular their dendritic and sinuous planform shapes, steep and linear longitudinal profiles, and cross-sectional asymmetry and width. We also report breaks/changes in canyon longitudinal slope gradient, relief and slope-area regression models at the intersection with faults. Tectonic activity gives rise to two types of knickpoints in the Cook Strait Canyon. The first type consists of low slope gradient, rounded and diffusive knickpoints forming as a result of short wavelength folds or fault break outs and being restored to an equilibrium profile by upstream erosion and

  2. Late Tectonic history of Beaufort Sea - North Pacific area

    SciTech Connect

    McWhae, J.R.H.

    1985-02-01

    The Kaltag fault (and its northern associated splay, the Rapid fault array) is the sheared suture between the Eurasian-Alaskan plate and the North American plate in the area between the Mackenzie Delta and the Alaskan Border. This condition has been maintained throughout considerable additional phases of faulting and folding from mid-Cretaceous to the present. Previously, the Alaskan plate had been the northwestern nose of the North America plate. The interplate suture was deflected to the north as the Canadian Shield was approached. The Kaltag fault continued northeastward 2000 km seaward of the Sverdrup rim, northwest of the Canadian Arctic Island, and north of Greenland. The driving force was directed from the southwest by the Eurasian plate after its collision in Early Cretaceous (Hauterivian) with the North American plate and the docking of north-moving exotic terranes from the Pacific. During the early Tertiary, perhaps in concert with the accretion of the Okhotsk block to the Asian plate north of Japan, the northern Pacific subduction zone jumped southward to the Aleutian Arc where it has persisted until today. A distance of 800 km separates the stable shelf of the Canadian craton, at the Alberta Foothills thrust belt, from the subduction zone off Vancouver Island. The foreland thrust belt and the accretion of exotic terranes in Mesozoic and Tertiary times extended the continental crust of the North American plate westward to the present active transform margin with the Pacific plate along the Queen Charlotte fault zone.

  3. Sedimentary and tectonic controls on oil occurrences in the traditional producing area, Barinas Subbasin, Western Venezuela

    SciTech Connect

    Daal, J.; Martinez, G.; Salas, J.

    1996-12-31

    A Stratigraphic and Tectonic model explains the oil-field locations in the Traditional Producing Area of the Barinas Subbasin, Western Venezuela. The database for the model includes a 585-km{sup 2} 3-D seismic survey, as well as petrophysical, lithologic and biostratigraphic data from Cretaceous and Tertiary sediments. A long-term relative sea level rise from Albian through Campanian (Cretaceous) time, coincident with passive-margin basin subsidence, resulted in onlap of marginal marine sands and marine-shelf limestones and shales over crystalline metamorphic rocks of the Guayana Shield Basement. Facies changes in the Cretaceous Aguardiente, Escandalosa, and Navay Formations are related mainly to eustatic sea level changes. A tectonic pulse deformed these sediments in Late Maastrichtian to Paleocene time. An erosional unconformity that developed atop this deformed Cretaceous section relates to tectonic uplift and not to sea-level change. Onlap of Middle Eocene marine transgressive Gobernador Fm. sands and Masparrito Fm. limestones over this unconformity was driven by increased tectonic subsidence. Accelerated tectonic subsidence drowned the Masparrito carbonate platform and led to deposition of a condensed section within the lower Paguey Formation; this condensed section marks a tectonic Maximum Flooding Surface not related to eustatic sea level change. After deposition of the Eocene Paguey, and just prior to deposition of the Oligo-Miocene Parangula Formation, a second tectonic event reactivated older faults and led to growth of structural traps for Cretaceous and Eocene reservoirs. Both tectonic and eustatic events have combined to control oil occurrence in the Barinas Subbasin.

  4. The Karoo igneous province — A problem area for inferring tectonic setting from basalt geochemistry

    NASA Astrophysics Data System (ADS)

    Duncan, Andrew R.

    1987-06-01

    Tholeiitic basalts and associated intrusives are the major component of the Karoo igneous province. They are of Mesozoic age and constitute one of the world's classic continental flood basalt (CFB) provinces. It has been argued that most Karoo basalts have not undergone significant contamination with continental crust and that their lithospheric mantle source areas were enriched in incompatible minor and trace elements during the Proterozoic. The only exceptions to this are late-stage MORB-like dolerites near the present-day continental margins which are considered to be of asthenospheric origin. When data for the "southern" Karoo basalts are plotted on many of the geochemical discriminant diagrams which have been used to infer tectonic setting, essentially all of them would be classified as calc-alkali basalts (CAB's) or low-K tholeiites. Virtually none of them plot in the compositional fields designated as characteristic of "within-plate" basalts. There is little likelihood that the compositions of the Karoo basalts can be controlled by active subduction at the time of their eruption and no convincing evidence that a "subduction component" has been added to the subcontinental lithospheric mantle under the entire area in which the basalts crop out. It must be concluded that the mantle source areas for CAB's and the southern Karoo basalts have marked similarities. In contrast, the data for "northern" Karoo basalts largely plot in the "within-plate" field on geochemical discriminant diagrams. Available data suggest that the source composition and/or the restite mineralogy and degree of partial melting are different for southern and northern Karoo basalts. There is no evidence for any difference in tectonic setting between the southern and northern Karoo basalts at the time they were erupted. This appears to be clear evidence that specific mantle source characteristics and/or magmatic processes can vary within a single CFB province to an extent that renders at least

  5. Crustal structure and active tectonics in the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Brückl, E.; Behm, M.; Decker, K.; Grad, M.; Guterch, A.; Keller, G. R.; Thybo, H.

    2010-04-01

    During the last decade, a series of controlled source seismic experiments brought new insight into the crustal and lithospheric structure of the Eastern Alps and their adjacent tectonic provinces. A fragmentation of the lithosphere into three blocks, Europe (EU), Adria (AD), and the new Pannonian fragment (PA), was interpreted and a triple junction was inferred. The goal of this study has been to relate these deep crustal structures to active tectonics. We used elastic plate modeling to reconsider the Moho fragmentation. We interpret subduction of EU below AD and PA from north to south and underthusting of AD mantle below PA from southwest to northeast. The Moho fragmentation correlates well with major upper crustal structures and is supported by gravity, seismic, and geodetic data. An analysis of crustal thickening suggests that active convergence is associated with continued thrusting and lateral extrusion in the central Eastern Alps and thickening of the Adriatic indenter under the Southern Alps. According to the velocity relations at the triple junction, PA moves relative to EU and AD along ENE and SE striking faults, mainly by strike slip. An eastward directed extensional component is compensated by the lateral extrusion of the central Eastern Alps. The Periadriatic (Insubric) line east of the triple junction and the mid-Hungarian fault zone have relatively recently lost their role as first-order active structures. We favor the idea that the Pannonian fragment and the TISZA block merged to a "soft" microplate surrounded by the Eastern and Southern Alpine, Carpathian, and Dinaric orogens.

  6. Past and present active sedimentation and tectonics in the South Alboran Sea

    NASA Astrophysics Data System (ADS)

    d'Acremont, E.; Gorini, C.; El Abbassi, M.; Farran, M.; Leroy, S.; Mercier de Lépinay, B.; Migeon, S.; Poort, J.; Ammar, A.; Smit, J.; Do Couto, D.; Ercilla, G.; Alonso, B.

    2012-04-01

    Since the Tortonian, the thinned continental crust and the overlying sedimentary cover of the Alboran Sea are submitted to tectonic inversion due to the convergence between Eurasia and Africa. The past and present deformation is significant along the Moroccan margin where the MARLBORO-1 cruise in 2011, acquired 1100 km of mid-resolution seismic reflection along 20 profiles perpendicular and parallel to the margin, off Al Hoceima, to latitude 36°N. The study area located on the Xauen/Tofino banks and the South Alboran ridge off Morocco, shows signs of both past and present strong tectonic deformation, mass-movement deposits (mostly slides and mass flow deposits), and contourites. The lateral and longitudinal evolution of contourites and mass movement deposits and the geometric relationships between those deposits and active tectonic structures have been studied. In the distal margin, contourites and gravitational instabilities are the depositional systems that best record the tectonic signal of the area since at least the Messinian. On the two flanks of the Xauen/Tofino and South Alboran ridge, the sedimentary register affected by growth-faults is mainly composed of contourites. Internal strata pattern, spatial and temporal distribution of thickness and depocenters, and discontinuities help to infer sedimentary processes and their interaction with tectonics. In the southern Alboran Sea where the bathymetry shows abrupt slopes, the recurrent seismic activity seems to be the main factor triggering mass wasting as witnessed by the Mass transport complexes (MTCs). Recent MTCs originate from escarpments on the edge of the contourites. However, in most cases the seismic reflection data show the depositional bodies of numerous slides linked to the activity of growth-faults and thrusts observed on the Xauen and Tofino Bank's north flanks. Tectonic inversion is recorded since the late Miocene with an acceleration of the uplift and compressional activity evidenced during

  7. Evidence of Tectonic Fractures as Magma Conduits in the Prometheus Area on Io

    NASA Astrophysics Data System (ADS)

    Leone, G.; Davies, A. G.; Wilson, L.; Williams, D. A.; Keszthelyi, L. P.

    2007-12-01

    As previously observed during the preliminary analysis of the first Galileo high resolution imaging [1], magma stored in a shallow reservoir exploited a vent along a tectonic fissure extending from the southern corner of the Prometheus patera [2, 3] to feed the long lava flows located in the flow field west of the Prometheus Mesa (see NASA image PIA02565 (Sources of Volcanic Plumes Near Prometheus). Recent analysis of the I24 and I27 imagery have shown that lava flows have been erupted from the westernmost of the tectonic fractures which is connected to the southern tip of the patera and to the eastern hotspot in the inset image in NASA image PIA02512 (Ongoing Geologic Activity at Prometheus Volcano, Io), thus suggesting that the fractures could be directly linked to the Prometheus plumbing system favouring a path to the surface for rising magmas. Although some flows, perhaps the most recent, come from this fracture, we cannot rule out patera overflows yet as a possible source of some of the southern flow field (as well as the northern flows coming out of the patera) due to the low resolution of the available images. Further analysis of the I24 data also shows that the south-eastern margin of the flow field does not contain vents and its morphology is suggestive of embayment in the rough topography along the main fault which heads to the southern tip of the Prometheus patera rather than originating from it as previously thought in the preliminary observations. The tectonic scenario observed in the Prometheus area, mainly thrust faults, is consistent with the horizontal stress, much greater than the (essentially lithostatic) vertical stress component throughout most of the lithosphere of Io, due to the volcanic activity which produces the high eruptive resurfacing rate and the consequent subsidence of the crust. References: [1] McEwen et al., Science 288, 1193, 2000. [2] Davies et al., Icarus 184, 460, 2006. [3] Keszthelyi et al., JGR 106, 33,025, 2001. Part of this

  8. Drilling to investigate processes in active tectonics and magmatism

    NASA Astrophysics Data System (ADS)

    Shervais, J.; Evans, J.; Toy, V.; Kirkpatrick, J.; Clarke, A.; Eichelberger, J.

    2014-12-01

    Coordinated drilling efforts are an important method to investigate active tectonics and magmatic processes related to faults and volcanoes. The US National Science Foundation (NSF) recently sponsored a series of workshops to define the nature of future continental drilling efforts. As part of this series, we convened a workshop to explore how continental scientific drilling can be used to better understand active tectonic and magmatic processes. The workshop, held in Park City, Utah, in May 2013, was attended by 41 investigators from seven countries. Participants were asked to define compelling scientific justifications for examining problems that can be addressed by coordinated programs of continental scientific drilling and related site investigations. They were also asked to evaluate a wide range of proposed drilling projects, based on white papers submitted prior to the workshop. Participants working on faults and fault zone processes highlighted two overarching topics with exciting potential for future scientific drilling research: (1) the seismic cycle and (2) the mechanics and architecture of fault zones. Recommended projects target fundamental mechanical processes and controls on faulting, and range from induced earthquakes and earthquake initiation to investigations of detachment fault mechanics and fluid flow in fault zones. Participants working on active volcanism identified five themes: the volcano eruption cycle; eruption sustainability, near-field stresses, and system recovery; eruption hazards; verification of geophysical models; and interactions with other Earth systems. Recommended projects address problems that are transferrable to other volcanic systems, such as improved methods for identifying eruption history and constraining the rheological structure of shallow caldera regions. Participants working on chemical geodynamics identified four major themes: large igneous provinces (LIPs), ocean islands, continental hotspot tracks and rifts, and

  9. Tectonic activity and structural features of active intracontinental normal faults in the Weihe Graben, central China

    NASA Astrophysics Data System (ADS)

    Rao, Gang; Lin, Aiming; Yan, Bing; Jia, Dong; Wu, Xiaojun

    2014-12-01

    This study examines the tectonic activity and structural features of active normal faults in the Weihe Graben, central China. The Weihe Graben is an area with a high level of historic seismicity, and it is one of the intracontinental systems that developed since Tertiary in the extensional environment around the Ordos Block. Analysis of high-resolution remote-sensing imagery data, field observations, and radiocarbon dating results reveal the following: i) active normal faults are mainly developed within a zone < 500 m wide along the southern border of the eastern part of the Weihe Graben; ii) the active faults that have been identified are characterized by stepwise fault scarps dipping into the graben at angles of 40°-71°; iii) there are numerous discontinuous individual fault traces, ranging in length from a few tens of meters to 450 m (generally < 200 m); iv) fault zone structures, topographic features, and fault striations on the main fault planes indicate almost pure normal-slip; and v) late Pleistocene-Holocene terrace risers, loess, and alluvial deposits have been vertically offset by up to ~ 80 m, with a non-uniform dip-slip rate (throw-rates) ranging from ~ 2.1 to 5.7 mm/yr, mostly 2-3 mm/yr. Our results reveal that active normal faults have been developing in the Weihe Graben under an ongoing extensional environment, probably associated with the pre-existing graben and spreading of the continental crust, and this is in contrast with the Ordos Block and neighboring orogenic regions. These results provide new insights into the nature of extensional tectonic deformation in intracontinental graben systems.

  10. Quaternary volcanism, tectonics, and sedimentation in the Idaho National Engineering Laboratory area

    SciTech Connect

    Hackett, W.R.; Smith, R.P.

    1992-01-01

    In this article, we discuss the regional context and describe localities for a two-day field excursion in the vicinity of the Idaho National Engineering Laboratory (INEL). We address several geologic themes: (1) Late Cenozoic, bimodal volcanism of the Eastern Snake River Plain (ESRP), (2) the regional tectonics and structural geology of the Basin and Range province to the northwest of the ESRP, (3) fluvial, lacustrine, and aeolian sedimentation in the INEL area, and (4) the influence of Quaternary volcanism and tectonics on sedimentation near the INEL.

  11. Quaternary volcanism, tectonics, and sedimentation in the Idaho National Engineering Laboratory area

    SciTech Connect

    Hackett, W.R.; Smith, R.P.

    1992-09-01

    In this article, we discuss the regional context and describe localities for a two-day field excursion in the vicinity of the Idaho National Engineering Laboratory (INEL). We address several geologic themes: (1) Late Cenozoic, bimodal volcanism of the Eastern Snake River Plain (ESRP), (2) the regional tectonics and structural geology of the Basin and Range province to the northwest of the ESRP, (3) fluvial, lacustrine, and aeolian sedimentation in the INEL area, and (4) the influence of Quaternary volcanism and tectonics on sedimentation near the INEL.

  12. Reinterpretation of Mesozoic and Cenozoic tectonic events, Mountain Pass area, northeastern San Bernardino County, California

    SciTech Connect

    Nance, M.A. . Geology Dept.)

    1993-04-01

    Detailed mapping, stratigraphic structural analysis in the Mountain Pass area has resulted in a reinterpretation of Mesozoic and Cenozoic tectonic events in the area. Mesozoic events are characterized by north vergent folds and thrust faults followed by east vergent thrusting. Folding created two synclines and an anticline which were than cut at different stratigraphic levels by subsequent thrust faults. Thrusting created composite tectono-stratigraphic sections containing autochthonous, para-autothonous, and allochthonous sections. Normal faults cutting these composite sections including North, Kokoweef, White Line, and Piute fault must be post-thrusting, not pre-thrusting as in previous interpretations. Detailed study of these faults results in differentiation of at least three orders of faults and suggest they represent Cenozoic extension correlated with regional extensional events between 11 and 19 my. Mesozoic stratigraphy reflects regional orogenic uplift, magmatic activity, and thrusting. Inclusion of Kaibab clasts in the Chinle, Kaibab and Chinle clasts in the Aztec, and Chinle, Aztec, and previously deposited Delfonte Volcanics clasts in the younger members of the Delfonte Volcanics suggest regional uplift prior to the thrusting of Cambrian Bonanza King over Delfonte Volcanics by the Mescal Thrust fault. The absence of clasts younger than Kaibab argues against pre-thrusting activity for the Kokoweef fault.

  13. UAV's for active tectonics : case example from the Longitudinal Valley and the Chishan Faults (Southern Taiwan)

    NASA Astrophysics Data System (ADS)

    Deffontaines, Benoit; Chang, Kuo-Jen; Chan, Yu-Chang; Chen, Rou-Fei; Hsieh, Yu-Chung

    2015-04-01

    Taiwan is a case example to study active tectonics due to the active NW-SE collision of the Philippine and Eurasian Sea Plates as the whole convergence reaches 10cm/y. In order to decipher the structural active tectonics geometry, we used herein UAV's to get high resolution Digital Terrain Model (DTM) in local active tectonics key areas. Classical photo-interpretation where then developped in order to structurally interprete these data, confirmed by field studies. Two location had first been choosen in order to highlight the contribution of such high resolution DTM in SW Taiwan on the Longitudinal Valley Fault (SE Taiwan) on its southern branch from Pinting to Luyeh terraces (Pinanshan) where UAV's lead to better interprete the location of the outcropping active deformations. Combined with available GPS data and PALSAR interferometry (Deffontaines et Champenois et al., submitted) it is then possible to reconstruct the way of the present deformation in this local area. In the Pinting terraces, If the western branch of the fault correspond to an outcroping thrust fault, the eastern branch act as a a growing active anticline that may be characterized and quantified independantly. The interpretation of the UAV's high resolution DTM data on the Chishan Fault (SW Taiwan) reveals also the geometry of the outcropping active faults complex structural behaviour. If the Chishan Fault act as a thrusting in its northern tip (close to Chishan city), it acts as a right lateral strike-slip fault north of Chaoshan (Kaohsiung city) as described by Deffontaines et al. 2014. Therefore UAV's are a so useful tool to get very high resolution topographic data in Taiwan that are of great help to get the geometry of the active neotectonic structures in Taiwan.

  14. Geomorphic signature of active tectonics in the southern Abruzzi Periadriatic hilly belt (Central Italy)

    NASA Astrophysics Data System (ADS)

    Racano, Simone; Fubelli, Giandomenico; Centamore, Ernesto; Dramis, Francesco

    2016-04-01

    The geo-structural setting of the southern Abruzzi hilly belt that stretches from the northeastern front of the Maiella Massif to the Adriatic coast is characterized by deep-seated northeast verging thrusts masked by a thick cover of Late Pliocene-Middle Pleistocene marine deposits. Most authors consider this area tectonically inactive while only few of them support the hypothesis of its recent activity from the analysis of the river network pattern. Geological and geomorphological investigations carried out in the area have clearly shown the occurrence of surface deformations resulting from the continued activity of compressive tectonics up to recent times. The analysis of the study area by of a 10 m resolution DTM (using the open-source QGIS software) confirmed and supplemented field observations. Particularly significant in this context is the topographic setting of the alluvial strath terraces in the river valleys that develop transversally to the buried thrusts. In correspondence of these structures, topographic highs have grown up displacing the middle-Pleistocene planation surface developed on top of the hilly belt, from the Maiella piedmont to the coastal zone, and diverting laterally the river courses uphill. In the same places, as along the Alento and Foro rivers that cross by antecedence the grown up topographic highs, the long profiles of terraces bend eastward and the height difference between the terrace orders, essentially related all around the area to the Quaternary regional uplift, strongly increases. In some cases, surficial faults have lowered the terraces into graben troughs or have displaced them until assuming an uphill trend. This recent tectonic activity should be taken in account in assessing the seismic hazard of the study area.

  15. Active tectonics of the eastern Sunda and Banda arcs

    NASA Astrophysics Data System (ADS)

    McCaffrey, Robert

    1988-12-01

    The mechanism of collision of the Australian continent with the East Sunda and Banda island arcs is examined. Depths and fault plane solutions of large earthquakes are estimated and are used to constrain the active, shallow tectonics of the collision zone. The convergence of the Australian continent with eastern Indonesia is accommodated to some degree by N-S crustal shortening throughout the forearc, arc, and back arc regions. Within the back arc (the Banda Basin), strike-slip and thrust faulting reveal convergence between Timor and Seram. Back arc thrusting plays an important role in the convergence across the collision zone. The Banda Basin probably formed as slices of northern New Guinea were transported westward with the Pacific plate and collided with an island arc in eastern Sulawesi.

  16. Tectonic evidence for the ongoing Africa-Eurasia convergence in central Mediterranean foreland areas: A journey among long-lived shear zones, large earthquakes, and elusive fault motions

    NASA Astrophysics Data System (ADS)

    di Bucci, Daniela; Burrato, Pierfrancesco; Vannoli, Paola; Valensise, Gianluca

    2010-12-01

    We investigate the role of the Africa-Eurasia convergence in the recent tectonic evolution of the central Mediterranean. To this end we focused on two sectors of the Adriatic-Hyblean foreland of the Apennine-Maghrebian chain as they allow tectonic evidence for relative plate motions to be analyzed aside from the masking effect of other more local tectonic phenomena (e.g., subduction, chain building, etc.). We present a thorough review of data and interpretations on two major shear zones cutting these foreland sectors: the E-W Molise-Gondola in central Adriatic and the N-S Vizzini-Scicli in southern Sicily. The selected foreland areas exhibit remarkable similarities, including an unexpectedly high level of seismicity and the presence of the investigated shear zones since the Mesozoic. We analyze the tectonic framework, active tectonics, and seismicity of each of the foreland areas, highlighting the evolution of the tectonic understanding. In both areas, we find that current strains at midcrustal levels seem to respond to the same far-field force oriented NNW-SSE to NW-SE, similar to the orientation of the Africa-Eurasia convergence. We conclude that this convergence plays a primary role in the seismotectonics of the central Mediterranean and is partly accommodated by the reactivation of large Mesozoic shear zones.

  17. Climate dominated topography in a tectonically active mountain range

    NASA Astrophysics Data System (ADS)

    Adams, B. A.; Ehlers, T. A.

    2015-12-01

    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The broad spatial trend in channel steepness values suggests that the locus of high rock uplift rates is coincident with the rugged range core, in a similar position as high temperature and pressure lithologies, but not in the low lying foothills as has been previously suggested by low-temperature thermochronometry. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns. We demonstrate the same topographic effects are recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on topography makes the argument of mountain range steadiness untenable in significantly glaciated settings. Furthermore, our results suggest that most glaciated Cenozoic ranges are likely still in a mode of readjustment as fluvial systems change topography and erosion rates to equilibrate with rock uplift rates.

  18. Spatial analysis of Budovar stream catchment (Srem Loess Plateau, Serbia) in a tectonically active region

    NASA Astrophysics Data System (ADS)

    Jovanovic, Mladjen; Rvovic, Ivan; Sorak, Rada; Petrovic, Milos

    2016-04-01

    Budovar is the far longest stream on Srem Loess Plateau, with a length of a 52 km, and catchment area of 245 km2. Budovar stream drains a quite complex landscape in terms of generally flat loess plateau, with elevations decreasing gradually southeastward - from 213 m at slopes of Fru\\vska Gora Mountain to 70,9 m at the confluence with Danube river. The youngest (Pleistocene/Holocene) sedimentary formations in the catchment vary from slope loess on Fru\\vska Gora Mtn. in upper part, through typical plateau loess in middle part, and the finest bog-sediments in tectonic depressions in lower part. These deposits lie over the bog-lake-terrestrial sediments with thickness over 100 m. According the geodetic measurements, uplift of Fru\\vska Gora Mtn., which has been the strongest during the Middle Pleistocene, is still present, with rates of up to 1 mm/y in contrast of general uplift of the area, subsidence is recorded in two distinct parts of the catchment. Spatial analysis is done using a DEM, generated in ArcGIS 10.0 from the elevation points, 10 m contours and stream coverage available in 1:25.000 topographical maps. Both longitudinal and cross-section profiles of the valley reflect the influence of tectonic distortions and climatic fluctuations. Valleys in Budovar catchment have composite character - the valleys cross-sections vary from deep incised V-shape, reversed trapezoid shape and completely flat valleys in tectonic depressions. Moreover, there is almost no correlation between the shape of cross-sectional profiles and the direction of curvature of the main valley's long axis (left/right or straight), suggesting that the tectonic activity has the key role in shaping. The width of valleys in Budovar catchment area is in sharp contrast with present stream discharge, which suggests strong climate fluctuations since Upper Pleistocene. The longitudinal profiles also shows signs of kickpoints and some short reaches with increasing elevation in the flow direction. Key

  19. New constraints on the active tectonic deformation of the Aegean

    USGS Publications Warehouse

    Nyst, M.; Thatcher, W.

    2004-01-01

    revealed by seismicity, active faulting, fault geomorphology, and earthquake fault plane solutions, continental tectonics, at least in the Aegean, is to first order very similar to global plate tectonics and obeys the same simple kinematic rules. Although the widespread distribution of Aegean seismicity and active faulting might suggest a rather spatially homogeneous seismic hazard, the focusing of deformation near microplate boundaries implies the highest hazard is comparably localized.

  20. Topographyc metrics in the southern sector of the Marche foothills: implication for active tectonic analysis

    NASA Astrophysics Data System (ADS)

    Materazzi, Marco; Aringoli, Domenico; Carducci, Tamara; Cavitolo, Paolo; Farabollini, Piero; Giacopetti, Marco; Pambianchi, Gilberto; Tondi, Emanuele; Troiani, Francesco

    2016-04-01

    Quantitative geomorphic analysis can be provided a useful contribution to the study of recent tectonics. Some parameters, that quantify the channels morphology, as the Stream Length-Gradient (SL) Index (Hack, 1973) and the Steepness (Ks) Index (Flint, 1974), are generally used to detect anomalies on the expected concave-up equilibrium stream-profile, which can result in local abrupt changes in stream gradient (i.e., knickpoints) and/or broad convexities on stream long-profiles extending for tens of kilometres (i.e., knickzones). The main goal of this work is the study of the morphological and morphometrical features in the southern sector of the Marche Region, with the aim to gain new knowledge on the influences of rock resistance and rock uplift on the fluvial and topographic system. The investigated area is situated in central Italy and it extends from the axial zone of the Umbria-Marche Apennines to the Adriatic Sea, including the southern sector of the Marche Region and belongs to the foredeep domain of the Apennines orogenic system, which has affected by tectonic activity up to very recent times. The rheology of outcropping deposits doesn't allow the strain to be easily recorded at the outcrop scale. The analyses have been aimed at to test the sensitivity of both SL and Ks for evaluating active crustal deformations, acting at different wavelengths on land surface, within a low tectonically active thrust-and-fold belt. Additional purpose was the understanding of the pattern of regional differential crustal activity in the topographic arrangement of the study area In this research project two sets of analysis were conducted. References Hack J.T. 1973. Stream-profile analysis and stream-gradient index. Journal of Research of the U.S. Geological Survey, 1, 421-429. Flint J.J. 1974. Stream gradient as a function of order, magnitude and discharge. Water Resources Research, 10, 969-973.

  1. Detection and Analysis of Deep Seated Gravitational Slope Deformation and Relations with the Active Tectonics

    NASA Astrophysics Data System (ADS)

    Moro, M.; Saroli, M.; Lancia, M.; Albano, M.; Lo Sardo, L.; Stramondo, S.

    2015-12-01

    Modern geomorphological investigations focused on the definition of major factors conditioning the landscape evolution. The interaction of some of these factors as the litho-structural setting, the local relief, the tectonic activity, the climatic conditions and the seismicity plays a key-role in determining large scale slope instability phenomena which display the general morphological features of deep seated gravitational deformations (DSGD). The present work aims to detect the large scale gravitational deformation and relations with the active tectonics affecting the Abruzzo Region and to provide a description of the morphologic features of the deformations by means of aerial photograph interpretation, geological/geomorphological field surveys and DInSAR data. The investigated areas are morphologically characterized by significant elevation changes due to the presence of high mountain peaks, separated from surrounding depressed areas by steep escarpments, frequently represented by active faults. Consequently, relief energy favours the development of gravity-driven deformations. These deformations seem to be superimposed on and influenced by the inherited structural and tectonic pattern, related to the sin- and post-thrusting evolution. The morphological evidences of these phenomena, are represented by landslides, sackungen or rock-flows, lateral spreads and block slides. DInSAR analysis measured deformation of the large scale gravitative phenomena previously identified through aerial-photo analysis. DSGD may evolve in rapid, catastrophic mass movements and this paroxistic evolution of the deformations may be triggered by high magnitude seismic events. These assumptions point out the great importance of mapping in detail large scale slope instability phenomena in relation to the active faults, in a perspective of land-use planning such as the Abruzzo Region characterized by a high magnitude historical seismicity.

  2. Thin-skinned tectonics of the Upper Ojai Valley and Sulphur Mountain area, Ventura basin, California

    SciTech Connect

    Huftile, G.J. )

    1991-08-01

    By integrating surface mapping with subsurface well data and drawing cross sections and subsurface maps, the geometry of shallow structures and their geologic history of the Upper Ojai Valley of California can be reconstructed. The geometry of shallow structures, the geologic history, and the location of earthquake foci then offer constraints on the deep structure of this complex area. The Upper Ojai Valley is a tectonic depression between opposing reverse faults. Its northern border is formed by the active, north-dipping San Cayetano fault, which has 6.0 km of stratigraphic separation in the Silverthread area of the Ojai oil field and 2.6 km of stratigraphic separation west of Sisar Creek. The fault dies out farther west in Ojai Valley, where the south-vergent shortening is transferred to a blind thrust. The southern border of the Upper Ojai Valley is formed by the Quaternary Lion fault set, which dips south and merges into the Sisar decollement within the south-dipping, ductile, lower Miocene Rincon formation. By the middle Pleistocene, the Sulphur Mountain anticlinorium and the Big Canyon syncline began forming as a fault-propagation fold; the fault-propagation fold is rooted in the Sisar decollement, a passive backthrust rising from a blind thrust at depth. The formation of the Sulphur Mountain anticlinorium was followed closely by the ramping of the south-dipping Lion fault set to the surface over the nonmarine upper Pleistocene Saugus Formation. To the east, the San Cayetano fault overrides and folds the Lion Fault set near the surface. Area-balancing of the deformation shows shortening of 15.5 km, and suggests a 17 km depth to the brittle-ductile transition.

  3. Tectonic framework of the Parkfield-Cholame area, central San Andreas fault zone, California

    SciTech Connect

    Sims, J.D.; Ross, D.C.; Irwin, W.P.

    1985-01-01

    Recent geologic mapping of the NW-trending San Andreas fault zone (SAFZ) in the southern Diablo Range reveals details of this structurally complex region. Movement on the fault juxtaposes dissimilar tectonic terranes. The region on the NE side is characterized by complexly folded and faulted rocks of the Franciscan assemblage, the Coast Range ophiolite, and sedimentary rocks of the Great Valley sequence and younger formations. The region on the SW side is characterized by crystalline basement rocks of the Salinia terrane overlain by slightly deformed Pliocene and Pleistocene gravel and Miocene and Pliocene sedimentary rocks. The active trace of the SAFZ is along the SW side of a belt of melange that separates the Salinia terrane from the terranes to the NE. The active main trace is notable for a right step over of about 1 km in the southern part of the area and a 5/sup 0/ left bend in the northern part of the area. The melange consists of highly sheared and deformed rocks of late Cenozoic units, and exotic blocks of granite, gabbro, and marble. Deformation of Late Cretaceous and younger rocks east of the SAFZ varies with their age as follows: 1) Late Cretaceous rocks are strongly deformed and overlain by late Cenozoic rocks with angular unconformity, 2) early(.) and middle Miocene rocks are the most complexly folded, 3) late Miocene and early Pliocene strata are less complexly deformed, and 4) Pliocene and Pleistocene rocks the least deformed. Folding resulted from north-south compression across the SAFZ since early (.) Miocene time.

  4. Venus: further evidence of impact cratering and tectonic activity from radar observations.

    PubMed

    Campbell, D B; Burns, B A; Boriakoff, V

    1979-06-29

    Earth-based radar images at a resolution of 10 kilometers show a diverse surface terrain on Venus, probably produced by both impact events and tectonic activity. Only a small number of craters of apparent impact origin are seen. Large-scale features show lineaments and parallel ridges suggesting tectonic origins.

  5. Tectonic activity on Pluto after the Charon-forming impact

    NASA Astrophysics Data System (ADS)

    Barr, Amy C.; Collins, Geoffrey C.

    2015-01-01

    The Pluto-Charon system, likely formed from an impact, has reached the endpoint of its tidal evolution. During its evolution into the dual-synchronous state, the equilibrium tidal figures of Pluto and Charon would have also evolved as angular momentum was transferred from Pluto's spin to Charon's orbit. The rate of tidal evolution is controlled by Pluto's interior physical and thermal state. We examine three interior models for Pluto: an undifferentiated rock/ice mixture, differentiated with ice above rock, and differentiated with an ocean. For the undifferentiated case without an ocean, the Pluto-Charon binary does not evolve to its current state unless its internal temperature Ti > 200K , which would likely lead to strong tidal heating, melting, and differentiation. Without an ocean, Pluto's interior temperature must be higher than 240 K for Charon to evolve on a time scale less than the age of the Solar System. Further tidal heating would likely create an ocean. If New Horizons finds evidence of ancient tidally-driven tectonic activity on either body, the most likely explanation is that Pluto had an internal ocean during Charon's orbital evolution.

  6. Hylton northwest field's tectonic effect on Suggs Ellenburger producing area, Nolan County, Texas

    SciTech Connect

    Hoffacker, B.F. Jr.

    1987-02-01

    An evaluation of the geology of Hylton Northwest field in southeastern Nolan County, Texas, indicates that the pre-Pennsylvanian tectonics associated with this field may have affected the producing zone of Suggs Ellenburger field 6 mi (9 km) west. Both fields are located along the Fort Chadbourne fault system of the Eastern shelf of the Midland basin. The study of the depositional environment of the Suggs Ellenburger field reveals some interesting aspects of the tectonostratigraphic terrane that appears to have in part influenced the development of the reservoir rock. The tectonics of the Cambrian-Ordovician (Ellenburger) period in Hylton Northwest field created a southwest-trending fault system with associated fractures. The fractures allowed percolating surface waters to leach carbonate rocks in the area, creating vuggy secondary porosity in the intercrystalline rock fabric. The faults were modified to a karst topography by periods of subaerial erosion of the Cambrian-Ordovician depositional plain. Sea level fluctuations that occurred in the area were associated with the alternating uplift and subsidence of the Hylton Northwest field's tectonic feature. As a result, environmental zones of porosity with varying vertical subaerial erosion formed within the overall Cambrian-Ordovician (Ellenburger) interval. The producing zone of the Suggs Ellenburger field occurs at approximately 6,400 ft (1,951 m).

  7. Sediment yield from the tectonically active semiarid Western Transverse Ranges of California

    USGS Publications Warehouse

    Warrick, J.A.; Mertes, L.A.K.

    2009-01-01

    Sediment yields from the world's rivers are generally highest from steep drainage basins with weak lithology, active tectonics, or severe land-use impacts. Here, we evaluate sediment yields from the Western Transverse Ranges of California in an attempt to explain why they are two- to tenfold greater than the surrounding areas of California. We found that suspended-sediment yields across the gauged basins of the Western Transverse Range during 1969-1999 varied by approximately an order of magnitude (740-5300 t/km2/yr). Similarly, fine-sediment concentrations for normalized discharge rates varied by almost two orders of magnitude (e.g., 1.3-110 g/L for the mean annual flood) for 11 previously unmonitored drainages of the Santa Ynez Mountains. Areas with high sediment yields consistently have weakly consolidated bedrock (Quaternary-Pliocene marine formations) and are associated with the highest rates of tectonic uplift of the region (>5 mm/yr). These regions are important to the sediment discharge budgets, because ???50% of the total suspended-sediment discharge from the Western Transverse Range is estimated to be generated within these regions, even though they represent only ???10% of the total watershed area. Previous estimates of suspended-sediment discharge from the Ventura River have likely been underestimated by ???50% because the gauging station is located immediately upstream of a high sediment yield region. We also found a significant and positive correlation between sediment yield and the percentage of a watershed with grassland and agricultural land use. These results suggest that there is adequate variation within the lithology, tectonics, and land use of the broader Western Transverse Range geologic province to induce large variations in sediment yield at the local scale. ?? 2009 Geological Society of America.

  8. Tectonic control of the damaged areas by land subsidence: Ameca, Jalisco Mexico, a study case

    NASA Astrophysics Data System (ADS)

    Rosas-Elguera, J.; Malagon, A.; Maciel, R.; Alatorre, M. A.; Perez, G.

    2009-04-01

    The Miocene to Quaternary Trans-Mexican Volcanic Belt (TMVB), one of the largest mexican volcanic arcs built on the North America plate, covers about 1000 km along central Mexico from the Pacific ocean to the Gulf of Mexico. The structure of west-central Mexico is dominated by a complex assemblage of crustal blocks bounded by major tectonic structures of the TMVB. These are the NW-SE Tepic-Zacoalco, the N-S Colima, and the E-W Chapala grabens, which separate the Jalisco and Michoacan blocks from the stable North American plate. The three grabens join south of Guadalajara to form what has been long interpreted as an active triple junction. The Tepic-Zacoalco rift is composed of the eastern part of the Plan de Barrancas-Santa Rosa graben and by the Ameca and Zacoalco half-grabens. The Ameca city is located in the Ameca half-graben. From 80´s several houses and buildings (more than 300) have been affected by land subsidence for more than two decades. The damage area follows a specific pattern with NW trend which is similar to the regional faults. The land subsidence is associated with the water extraction. We suggest that the distribution of the damage area is controlled by the fault system in combination with the water extraction. Because of the Ameca half-graben has been affected by historical and present day earthquakes and considering the subsurface geology (sandstones, siltstone intercalated with conglomerates) sudden collapses can be expected.

  9. An Integrated Geospatial System for earthquake precursors assessment in Vrancea tectonic active zone in Romania

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.

    2015-10-01

    With the development of space-based technologies to measure surface geophysical parameters and deformation at the boundaries of tectonic plates and large faults, earthquake science has entered a new era. Using time series satellite data for earthquake prediction, it is possible to pursue the behaviors of earthquake precursors in the future and to announce early warnings when the differences between the predicted value and the observed value exceed the pre-define threshold value. Starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (oC) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock. Also are recorded associated geomagnetic and ionospheric distrurbances. Vrancea tectonic active zone in Romania is characterized by a high seismic hazard in European- Mediterranean region, being responsible of strong or moderate intermediate depth and normal earthquakes generation on a confined epicentral area. Based on recorded geophysical parameters anomalies was developed an integrated geospatial system for earthquake precursors assessment in Vrancea active seismic zone. This system integrates derived from time series MODIS Terra/Aqua, NOAA-AVHRR, ASTER, Landsat TM/ETM satellite data multi geophysical parameters (land surface temperature -LST, outgoing long-wave radiation- OLR, and mean air temperature- AT as well as geomagnetic and ionospheric data in synergy with in-situ data for surveillance and forecasting of seismic events.

  10. Status report on the tectonic fracture and breccia study in the Vantage area

    SciTech Connect

    Chamness, M.A.; Tolan, T.L.

    1983-09-01

    This is a status report on preliminary observations and interpretations which are subject to change with future work. An area near Vantage Washington is currently being examined in order to determine the nature and extent of tectonic breccias and fractures related to faulting and folding in a synclinal area. This report describes the status of that study as of August 1983. The study consists of three phases: geologic mapping, location and description of breccias, and comparison to borehole data. Work completed to date is primarily geologic mapping and preliminary work on the location of breccia zones. 27 refs., 18 figs.

  11. Relative tectonics and debris flow hazards in the Beijing mountain area from DEM-derived geomorphic indices and drainage analysis

    NASA Astrophysics Data System (ADS)

    Cheng, Weiming; Wang, Nan; Zhao, Min; Zhao, Shangmin

    2016-03-01

    The geomorphic setting of the tectonically active area around Beijing is a result of complex interactions involving Yanshan neotectonic movements and processes of erosion and deposition. The Beijing Mountain study area contains the junction of two mountain ranges (the Yanshan Mountains and the Taihang Mountains). Tectonic activity has significantly influenced the drainage system and the geomorphic situation in the area, leading to a high probability of the development of debris flows, which is one of the major abrupt geological disasters in the region. Based on 30-m-resolution ASTER GDEM data, a total of 752 drainage basins were extracted using ArcGIS software. A total of 705 debris flow valleys were visually interpreted from ALOS satellite images and published documents. Seven geomorphic indices were calculated for each basin including the relief amplitude, the hypsometric integral, the stream length gradient, the basin shape indices, the fractal dimension, the asymmetry factor, and the ratio of the valley floor width to the height. These geomorphic indices were divided into five classes and the ratio of the number of the debris flow valleys to the number of the drainage basins for each geomorphic index was computed and analyzed for every class. Average class values of the seven indices were used to derive an index of relative active tectonics (IRAT). The ratio of the number of the debris flow valleys to the number of the drainage basins was computed for every class of IRAT. The degree of probable risk level was then defined from the IRAT classes. Finally, the debris flow hazard was evaluated for each drainage basin based on the combined effect of probable risk level and occurrence frequency of the debris flows. The result showed a good correspondence between IRAT classes and the ratio of the number of the debris flow valleys to the number of the drainage basins. Approximately 65% of the drainage basins with occurred debris flow valleys are at a high risk level

  12. Quantative determination of geological and tectonic development under complex geological settings - Thrace Area, Turkey

    SciTech Connect

    Erdogan, L.T. ); Yuekler, M.A.

    1990-05-01

    Thrace area is composed of several subbasins, formed during the middle Eocene, overlying the metamorphic and granitic rocks of the Istranca Massif. Syndepositional fault patterns and variations in sedimentary thicknesses indicate that the subbasins evolved tectonically by northeast-southwest extension from the middle Eocene to early Paleocene. From the early Paleocene to early Miocene, the northern part of the area underwent northeast-southwest extension, whereas in the middle Miocene, northwest-southeast wrench-fault assemblage resulted in a clockwise rotation of the extension axes. Consequently, the right-lateral motion of the transform faults resulted in a north-south extension which prevailed until the late Pleistocene. During the last 1 m.y., the area was subjected to a major compression leading to rapid erosion in the central part of the area. A deterministic three-dimensional basin analysis model has been applied to quantify the geological and tectonic evolution of the subbasins. A total of 72 wells were simulated to determine compaction pressure, and temperature histories of the sedimentary sequences to set up the conceptual model. The validity of the conceptual model was then checked with the simulation of six seismic profiles before the full three-dimensional simulation of the area. The trends from the computed subsidence and uplift heat flow, and compaction maps as a function of time were checked against the observed stratigraphic and sedimentological data. The excellent match between the computed trends and observed isopachs, and erosions as determined from seismic data and depositional environments, aided in the quantification of the regional stratigraphy and tectonics. The combination of the computed heat flow and uncompacted isopach maps was used in determining stress-strain relationships in the subbasins as a function of time.

  13. Hazard analysis of active tectonics through geomorphometric parameters to cultural heritage conservation: the case of Paphos in Cyprus

    NASA Astrophysics Data System (ADS)

    Argyriou, A. V.; Sarris, A.; Alexakis, D.; Agapiou, A.; Themistocleous, K.; Lysandrou, V.; Hadjimitsis, D.

    2014-08-01

    Natural hazards, such as earthquakes, can have a large destructive effect on cultural heritage sites conservation. This study aims to assess from a geospatial perspective the risk from natural hazards for the archaeological sites and monuments and evaluate the potential tectonic activity impact on the cultural and historic heritage. Geomorphometric data derivatives that can be extracted from Digital Elevation Models (DEMs) provide information relevant with active tectonics. The specific extracted tectonic information when being used on the basis of analytical hierarchy process and weighted linear combination approach can offer an important robust approach. The ranking of the derived information relatively to specific criteria of weights can enhance the interrelationships and assemblages over neotectonics aspects. The outcomes of that methodological framework can propose an assessment approach for the spatial distribution of neotectonic activity and can become a useful tool to assessing seismic hazard for disaster risk reduction. The risk assessment aspects of such a hazard are being interlinked with the archaeological sites in order to highlight and examine those that are exposed on ongoing tectonic activity and seismic hazard. Paphos area in Cyprus has been used as the test bed for the particular analysis. The results show an important number of archaeological sites being located within zones of high degree of neotectonic activity.

  14. Structural analysis and evolution of the Hadong-Sancheong-Hwagae area in the Yeongnam massif, Korea: a NS-trend tectonic frame in the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Deok-Seon, Lee; Ji-Hoon, Kang

    2016-04-01

    The Hadong-Sancheong-Hwagae area in the Jirisan province of the Yeongnam massif, Korea, is mainly composed of Precambrian Hadong anorthosite complex (HAC), Precambrian Jirisan metamorphic rock complex (JMRC), Jurassic˜Triassic granitoids which intrude them, and Cretaceous sedimentary rocks which unconformably cover them. Lithofacies distribution and tectonic frame of the Precambrian constituent rocks mainly show a NS trend, unlike a general NE trend of those in the Korean Peninsula. To unravel the geological structures associated with the NS-trend tectonic frame which was built in the HAC and JMRC, we researched the structural characteristics of each deformation phase based on the geometric and kinematic features and the forming sequence of rock structures of the multi-deformed HAC and JMRC. The results indicate that the pre-Late Paleozoic geological structures of this area were formed at least through the following three times of ductile deformation phases. The D1 deformation happened due to the large-scale top-to-the SE shearing, and formed sheath or A-type folds and a regional NE trend of tectonic frame in the HAC and JMRC. The D2 deformation occurred under the EW-directed tectonic compression, and formed a regional NS trend of active and passive folds and Hadong ductile shear zone over 2.3˜1.4 km width, and transposed most of D1 tectonic frame into D1-2 composite tectonic frame. The extensive Hadong shear zone, which was formed in the mylonitization process accompanying the passive folding, was persistently developed along the eastern boundary of HAC and JMRC which corresponds to a limb of passive fold on a geological map scale. It produced a very strong mylonitic structure and stretching lineation. The NE-trend D1 structural elements were mainly reoriented into NS trend by the powerful active and passive folding. The D3 deformation occurred under the NS-trend tectonic compression environment, and formed EW-trend kink or open folds, and partially rearranged

  15. Threshold bedrock channels in tectonically active mountains with frequent mass wasting

    NASA Astrophysics Data System (ADS)

    Korup, O.; Hayakawa, Y. S.; Codilean, A.; Oguchi, T.

    2013-12-01

    Models of how mountain belts grow and erode through time largely rely on the paradigm of fluvial bedrock incision as the main motor of response to differences in rock uplift, thus setting base levels of erosion in tectonically active landscapes. Dynamic feedbacks between rock uplift, bedrock river geometry, and mass wasting have been encapsulated within the concept of threshold hillslopes that attain a mechanically critical inclination capable of adjusting to fluvial incision rates via decreased stability and commensurately more frequent landsliding. Here we provide data that challenge the widely held view that channel steepness records tectonic forcing more faithfully than hillslope inclination despite much robust empirical evidence of such links between bedrock-river geometry and hillslope mass wasting. We show that the volume mobilized by mass wasting depends more on local topographic relief and the sinuosity of bedrock rivers than their mean normalized channel steepness. We derive this counterintuitive observation from an unprecedented inventory of ~300,000 landslides covering the tectonically active Japanese archipelago with substantial differences in seismicity, lithology, vertical surface deformation, topography, and precipitation variability. Both total landslide number and volumes increase nonlinearly with mean local relief even in areas where the fraction of steepest channel segments attains a constant threshold well below the maximum topographic relief. Our data document for the first time that mass wasting increases systematically with preferential steepening of flatter channel segments. Yet concomitant changes in mean channel steepness are negligible such that it remains a largely insensitive predictor of landslide denudation. Further, minute increases in bedrock-river sinuosity lead to substantial reduction in landslide abundance and volumes. Our results underline that sinuosity (together with mean local relief) is a key morphometric variable for

  16. Active landsliding and landscape denudation in response to transient tectonic uplift, Northern California.

    NASA Astrophysics Data System (ADS)

    Bennett, G. L.; Roering, J. J.; Miller, S. R.; Kirby, E.; Schmidt, D. A.

    2014-12-01

    The northern Californian Coast ranges present a unique area to study landscape response to transient tectonic uplift. Studies have shown that an increase in uplift may be balanced by the rate of landsliding in settings of steady uplift. However, the landsliding response to transient tectonic uplift remains to be elucidated. The Californian Coast ranges are shaped by the northward migration of the Mendocino Triple Junction (MTJ), which geodynamic modeling suggests produces a transient double-humped uplift field. A major research question is whether we can detect a signature of this transient tectonic uplift in landslide activity and document how the channel network communicates this signal to hillslopes. Using air photos and Worldview imagery, we manually mapped more than 2000 earthflows and debris slides in the Eel and surrounding catchments that span the ~400 km-long region. The velocities of active earthflows were estimated by visually tracking features between images spanning 1993 to 2013. We mapped channel steepness from 10m NED DEMs in Topotoolbox 2 and developed a new tool to automatically define knickpoints along the channel network. Earthflows occur almost exclusively in a band of Franciscan mélange oriented along the MTJ transect whilst debris slides are more evenly distributed by lithology. Both earthflows and debris slides are clustered in the Eel catchment around the proposed uplift peaks and are largely absent outside of these zones. Within these areas of high landslide densities, we observe peaks in active earthflows adjacent to peaks in dormant earthflows to the south, suggesting that the signature of earthflow activity remains for a period of time once the uplift peak has passed. Landslide density, mean landslide area, and earthflow velocity all increase rapidly above threshold values of channel steepness and local relief. In the Eel catchment, where the zone of rapid uplift is commencing, landslides, particularly earth flows, are concentrated

  17. Fluvial systems response to rift margin tectonics: Makhtesh Ramon area, southern Israel

    NASA Astrophysics Data System (ADS)

    Ben-David, Ram; Eyal, Yehuda; Zilberman, Ezra; Bowman, Dan

    2002-06-01

    The geomorphic evolution of Makhtesh Ramon, a feather-shaped erosional valley, and the Nahal Neqarot drainage system to the south occurred largely in response to tectonic activity along the Dead Sea Rift and its western shoulder. Remnants of Miocene clastic sediments (Hazeva Formation) deposited on an erosional peneplain that formed over this area during the Oligocene epoch provide a datum plane for reconstructing subsequent fluvial evolution. These clastic remnants are presently located on the shoulders of Makhtesh Ramon at various elevations. The peneplain truncating the Makhtesh Ramon block has been tilted 0.7% northeastward since the Pliocene epoch (post-Hazeva Formation), whereas that of the Neqarot syncline, south of the Ramon, has been tilted 1.2%. The elliptical exposure of friable Lower Cretaceous sandstone, exposed in the core of the truncated Ramon structure, governed the development of a new ENE directed (riftward) drainage system through capture of streams that previously drained toward the Mediterranean Sea to the northwest. Incised fluvial gaps in the southern rim of Makhtesh Ramon and alluvial fan relicts within Makhtesh Ramon attest to original drainage into the Makhtesh from the south. Remnants of the Plio-Pleistocene Arava Conglomerate on the eastern end of the Neqarot syncline contain clasts from rocks exposed within Makhtesh Ramon, also indicating that streams flowed into the Makhtesh from the southern Neqarot block through the western gaps, then turning eastward and exiting the Makhtesh via the next (Sha'ar-Ramon) gap to the east. Further down-faulting of the Neqarot block during Mid-Late Pleistocene time led to westward retreat of the Neqarot valley and capture of the last stream flowing northward into the Ramon, leaving the modern Makhtesh Ramon isolated from the southern drainage system.

  18. Tectonic map of the Death Valley ground-water model area, Nevada and California

    SciTech Connect

    J.B. Workman; C.M. Menges; W.R. Page; E.B. Ekren; P.D. Rowley; G.L. Dixon

    2002-10-17

    The purpose of this map is to provide tectonic interpretations in the Death Valley ground-water model area to be incorporated into a transient ground-water flow model by the U.S. Geological Survey (D'Agnese, 2000; D'Agnese and Faunt, 1999; Faunt and others, 1999; and O'Brien and others, 1999). This work has been conducted in collaboration with the U.S. Department of Energy in order to assess regional ground-water flow near the Nevada Test Site (NTS) and the potential radioactive waste repository at Yucca Mountain. The map is centered on the NTS and its perimeter encircles the entire boundary of the numerical flow model area, covering a total area of 57,000 square kilometers. This tectonic map is a derivative map of the geologic map of the Death Valley ground-water model, Nevada and California (Workman and others, 2002). Structures portrayed on the tectonic map were selected from the geologic map based upon several criteria including amount of offset on faults, regional significance of structures, fault juxtaposition of rocks with significantly different hydrologic properties, and the hydrologic properties of the structures themselves. Inferred buried structures in the basins were included on the map (blue and light blue dotted lines) based on interpretation of geophysical data (Ponce and others, 2001; Ponce and Blakely, 2001; Blakely and Ponce, 2001). In addition, various regional trends of fault zones have been delineated which are composed of multiple smaller scale features. In some cases, these structures are deeply buried and their location is based primarily on geophysical evidence. In all cases, these zones (shown as broad red and blue stippled bands on the map) are significant structures in the region. Finally, surface exposures of Precambrian crystalline rocks and igneous intrusions of various ages are highlighted (red and blue patterns) on the map; these rocks generally act as barriers to groundwater flow unless significantly fractured.

  19. Hidden faults in the Gobi Desert (Inner Mongolia, China) - evidence for fault activity in a previously tectonically stable zone

    NASA Astrophysics Data System (ADS)

    Rudersdorf, Andreas; Haedke, Hanna; Reicherter, Klaus

    2013-04-01

    The Gaxun Nur Basin (GNB, also Ejina Basin, Hei River Basin, Ruoshui Basin) north of the Tibetan Plateau and the Hexi Corridor is an endorheic basin bounded by the Bei Shan ranges in the west, the Gobi Altai mountains in the north and the Badain Jaran sand desert in the east. The basin is fed from the south by the braided drainage system of the Hei He (Hei River) and its tributaries, which originate in the Qilian Shan; terminal lakes like the dried Gaxun Nur and Sogo Nur are and have been temporal. The sedimentary succession of up to 300 m comprises intercalations of not only alluvial deposits but also lake sediments and playa evaporites. The basin has been regarded as tectonically inactive by earlier authors; however, the dating of sediments from an earlier drill core in the basin center provided some implications for tectonic activity. Subsequent remote sensing efforts revealed large lineaments throughout the basin which are now considered as possible fault line fingerprints. We investigated well preserved Yardangs (clay terraces) in the northeastern part of the GNB, in the vicinity of the Juyanze (paleo) lake, and found evidence for Holocene active tectonics (seismites). We present a lithological analysis of the relevant sequences and conclusions on the recent tectonic activity within the study area.

  20. Drainage response to active tectonics and evolution of tectonic geomorphology across the Himalayan Frontal Thrust, Kumaun Himalaya

    NASA Astrophysics Data System (ADS)

    Luirei, Khayingshing; Bhakuni, Surendra S.; Kothyari, Girish Ch.

    2015-06-01

    We present the results of integrated studies of geomorphic indices of drainage networks and landforms developed across the mountain front along the Himalayan Frontal Thrust (HFT) between the Dabka and Baur rivers, Kumaun Himalaya. The HFT is a morphogenic structure in nature, creating a 100-m-high E-W trending escarpment that extends ~ 21 km. Geomorphological evidence indicates ~ 10.5 km westward migration of the Dabka River and ~ 5.2 km eastward migration of the Baur River. These migrations are a result of uplift of the hanging wall along the HFT. The HFT is offset by a transverse fault, which suggests that the latter postdates the reactivation of the HFT between 500 and 100 ka. Presence of different levels of strath terraces along the mountain front suggests the active nature of the HFT. To assess the relative tectonic activity, morphometric indices such as stream-gradient (SL) index, mountain front sinuosity (Smf) index, and ratio of valley floor width to valley height (Vf) have been analyzed. Results of the former two are consistent with the tectonic landforms developed in thrust zones. Paleochannels of the Dabka and Baur rivers are characterized by high Vf values while other valleys show low Vf values. Quaternary alluvial sediments have been deformed along the Pawalgarth Thrust, a splay of the HFT. Deformation has resulted in the formation of the Pawalgarh Anticline, a thrust-related asymmetric fold.

  1. Large and great earthquakes in the Shillong plateau-Assam valley area of Northeast India Region: Pop-up and transverse tectonics

    NASA Astrophysics Data System (ADS)

    Kayal, J. R.; Arefiev, S. S.; Baruah, Saurabh; Hazarika, D.; Gogoi, N.; Gautam, J. L.; Baruah, Santanu; Dorbath, C.; Tatevossian, R.

    2012-04-01

    The tectonic model of the Shillong plateau and Assam valley in the northeast India region, the source area for the 1897 great earthquake (Ms ~ 8.7) and for the four (1869, 1923, 1930 and 1943) large earthquakes (M. ≥ 7.0), is examined using the high precision data of a 20-station broadband seismic network. About 300 selected earthquakes M ≥ 3.0 recorded during 2001-2009 are analysed to study the seismicity and fault plane solutions. The dominating thrust/reverse faulting earthquakes in the western plateau may be explained by the proposed pop-up tectonics between two active boundary faults, the Oldham-Brahmaputra fault to the north and the Dapsi-Dauki thrust to the south, though the northern boundary fault is debated. The more intense normal and strike-slip faulting earthquakes in the eastern plateau (Mikir massif) and in the Assam valley, on the other hand, are well explained by transverse tectonics at the long and deep rooted Kopili fault that cuts across the Himalaya and caused the 2009 Bhutan earthquake (Mw 6.3). It is conjectured that the complex tectonics of the Shillong plateau and transverse tectonics at the Kopili fault make the region vulnerable for impending large earthquake(s).

  2. Active tectonics of the Oran (Algeria) Quaternary plain

    NASA Astrophysics Data System (ADS)

    youcef, Bouhadad; rabah, Bensalem; e-hadi, oubaiche

    2016-04-01

    The Oran region, in north-western Algeria, has been hit several times in the past by destructive moderate-sized and strong earthquakes. The Oran October 9th , 1790 (I0= X) was among the strongest seismic events in the western Mediterranean area comparable, if we consider the described effects, to the El- Asnam (1980, Ms=7.3) and Zemmouri (2003, Mw=6.8) earthquakes. Such strong seismic events requires the presence of major active geological structures that are re-activated several times in the past. In this work we present results of a multi- disciplinary study combining geomorphic analysis, field earthquake geological investigations and geophysical methods, undertaken to study the southern border of the Oran Quaternary plain. A 50 km long, SW-dipping and NE-SW trending active fault has been identified that showing clear quaternary deformation. Keywords: earthquake geology, active fault, geomorphic, geophysics, Algeria.

  3. Tectonic and deformation history of the Gyeonggi Massif in and around the Hongcheon area, and its implications in the tectonic evolution of the North China Craton

    NASA Astrophysics Data System (ADS)

    Yengkhom, Kesorjit S.; Lee, Byung Choon; Oh, Chang Whan; Yi, Kee Wook; Kang, Ji Hoon

    2015-04-01

    EG but not in the EGC. The D1deformation occurred during M1 metamorphism, and then the M2 metamorphism and 1867-1881 Ma igneous activities could have occurred together during post-collision tectonic stage. The M1 metamorphism and ca. 1867-1881 Ma post collision magmatism in the study area are well matched with the collision related metamorphism at ca. 1.90-1.93 Ga and post-collision igneous activities at ca.1.80-1.86 Ga along the Jiao-Liao-Ji belt in the North China Craton suggesting that M1 metamorphism could have caused by the collision along the Jiao-Liao-Ji belt. The M3 metamorphism occurred at ca.230-260 Ma and its peak metamorphic conditions were 720-730°C/13-14.5 kbar. The D2 deformation and the M3 intermediate-P/T metamorphism occurred during the Permo-Triassic collision event between the North China Craton and South China Craton. The study area might have located in the peripheral areas of the collision belt during the Paleoproterozoic and the Permo-Triassic time. The D3 deformation occurred at a time gap between the Permo-Triassic collision and the subduction related Jurassic intrusion in the Korean Peninsula.

  4. Neogene tectonics and modern geodynamics and seismicity of Pannonia north-eastern remote area (Ukrainian Transcarpathian yield)

    NASA Astrophysics Data System (ADS)

    Lozynak, Petro; Nazarevych, Andriy; Nazarevych, Lesya

    2010-05-01

    Pannonia north-eastern remote area (Ukrainian Transcarpathian yield) joins to East (Ukrainian) Carpathians and their geodynamic mode is interdependent from the alpine stage until now. Due to the detailed study in the last few years of structures of surface of basement and sedimentary layers of the Transcarpathian yield of postalpine ages (neogene - from early Miocene to Sarmatian and farther) (see Lozynak at al., 2002-2007) we have the possibility to trace the Neogene's tectonics of the region and its connection with modern geodynamics and seismicity of Ukrainian Transcarpathians and adjoining territories of Slovakia, Hungary and Romania. These data indicate that active orogenic processes (dominance of compression caused by a plate-tectonic processes) in this region to beginning of early miocene made off and began the process of formation of the Transcarpathian yield in his modern view (due to an output on the first plan of the plum-tectonic processes caused by Pannonian asthenolite?) (see Nazarevych A. and Nazarevych L., 2000-2007). The process of formation (origin) of yield (and the proper accumulation of sedimentary layers) began in his east part (in the area of border with Romania (Siget - Solotvyno)) at the beginning of early Miocene (about 23 million years ago), continue in north-western direction (in the rear of modern Carpathians) to the border with Slovakia at first as a narrow (10-15 km) bar (roughly during 2-4 million years) and then broadened (during next 2-3 million years) in north-eastern - south-west direction on all modern territory of the Transcarpathian yield. In future (in Sarmatian epoch, approximately from 12-14 to 10-11 million years ago) east part of yield (so-called Solotvyno depression) transgress to the mode of compression and raising with ending of intensive sedimentation, and in western part (so-called Tchop-Mukatcheve depression) the process of sagging was farther displaced westward and at present he is concentrated (by geodesic and

  5. New Mesotheriidae (Mammalia, Notoungulata, Typotheria), geochronology and tectonics of the Caragua area, northernmost Chile

    NASA Astrophysics Data System (ADS)

    Flynn, John J.; Croft, Darin A.; Charrier, Reynaldo; Wyss, André R.; Hérail, Gérard; García, Marcelo

    2005-05-01

    Few mammal fossils were known from the Altiplano or adjoining parts of northern Chile until recently. We report a partial mesotheriid palate from the vicinity of Caragua (Huaylas Formation) in northernmost Chile. The new material helps resolve contradictory taxonomic assignments (and age implications) of the two mesotheriid specimens previously reported from the area. Herein we refer all three mesotheriid specimens to a new taxon, Caraguatypotherium munozi, which is closely related to Plesiotypotherium, Typotheriopsis, Pseudotypotherium, and Mesotherium. This phylogenetic placement permits a revised biochronologic estimate of a post-Friasian/pre-Huayquerian (˜15-9 Ma) age for the Huaylas Formation, consistent with new radioisotopic dates from the upper Huaylas Formation and its bracketing stratigraphic units. Improved geochronologic control for the Huaylas Formation has important implications for the timing of tectonic events in the Precordillera/Altiplano of northern Chile. Structural, stratigraphic, and temporal data suggest the onset of rapid, progressive deformation shortly after the deposition of the older Zapahuira Formation, continuing at least partly through deposition of the Huaylas Formation. Deposition of the Huaylas Formation was short lived (between ˜10-12 Ma), possibly stemming from activity on the Copaquilla-Tignámar Fault in the eastern Precordillera. This deformation is associated with the development of the Oxaya Anticline and activity of the Ausipar Fault west of the study region on the frontal limb of the anticline in the westernmost Precordillera. Faulting and folding occurred rapidly, beginning at ˜11.4 Ma (shortly after deposition of the youngest extrusives of the Zapahuira Formation) and before ˜10.7 Ma (the age of the gently dipping horizons within the upper Huaylas Formation that overlie the mammal fossils and an intraformational unconformity). Mesotheriids are the only Tertiary fossil mammals known from the Precordillera of

  6. The Geomorphological Evolution of a Landscape in a Tectonically Active Region: the Sennwald Landslide

    NASA Astrophysics Data System (ADS)

    Aksay, Selçuk; Ivy-Ochs, Susan; Hippe, Kristina; Graemiger, Lorenz; Vockenhuber, Christof

    2016-04-01

    The Säntis nappe is a fold-and-thrust structure in eastern Switzerland consisting of numerous tectonic discontinuities that make rocks vulnerable to rock failure. The Sennwald landslide is one of those events that occurred due to the failure of Lower Cretaceous Helvetic limestones. This study reveals the surface exposure age of the event in relation to geological and tectonic setting, earthquake frequency of the Central Alps, and regional scale climate/weather influence. Our study comprises detailed mapping of landform features, thin section analysis of landslide boulder lithologies, landslide volume estimation, numerical DAN-3D run-out modelling, and the spatial and temporal relationship of the event. In the Sennwald landslide, 92 million m3 of limestones detached from the south-eastern wall of the Säntis nappe and slid with a maximum travel distance of ~4'500 m and a "fahrboeschung" angle of 15° along the SE-dipping sliding plane almost parallel to the orientation of the bedding plane. Numerical run-out modelling results match the extent and the thickness of landslide deposits as observed in the field. The original bedrock stratigraphy was preserved as geologically the top layer in the bedrock package travelled the farthest and the bottom layer came to rest closest to the release bedrock wall during the landslide. Velocities of maximum 90 m/s were obtained from the numerical run-out modelling. Total Cl and 36Cl were determined at ETH AMS facility with isotope dilution methods defined in the literature (Ivy-Ochs et al., 2004). Surface exposure ages of landslide deposits in the accumulation area are revealed from twelve boulders. The distribution of limestone boulders in the accumulation area, the exposure ages, and the numerical run-out modelling support the hypothesis that the Sennwald landslide was a single catastrophic event. The event is likely to have been triggered by at least light to moderate earthquakes (Mw=4.0-6.0). The historical and the last 40-year

  7. The Eocene-Miocene tectonic evolution of the Rif chain (Morocco): new data from the Jebha area

    NASA Astrophysics Data System (ADS)

    D'Assisi Tramparulo, Francesco; Ciarcia, Sabatino; El Ouaragli, Bilal; Vitale, Stefano; Najib Zaghloul, Mohamed

    2016-04-01

    Keywords: structural analysis, tectonics, shear bands, Miocene, Jebha Fault The Jebha area, located in the Central Rif, is a key sector to understand the orogenic evolution of the Rif chain. Here, the left lateral Jebha-Chrafate transfer fault, allowed, in the Miocene time, the westward migration of the internal thrust front. The structural analysis of the area revealed a complex tectonic history. The Eocene orogenic pulse produced the tectonic stacking of the Ghomaride thrust sheets. During the late Aquitanian and Langhian, under a dominant ENE-WSW shortening, imbrication of several Internal Dorsale Calcaire slices occurred. The following orogenic stage, characterized by a main SE tectonic transport, allowed the External Dorsale Calcaire to overthrust the Maghrebian Flysch Basin Units by means of a dominant thin-skinned tectonics. Synchronously with the buttressing following the collision of the allochthonous wedge against the External Rif domain, an out-of-sequence thrusting stage involved the Ghomaride and Dorsale Calcaire Units and a general back-thrusting deformed the entire tectonic pile. A renewal of the NE-SW shortening produced strike-slip faults and SW-verging folds and finally a radial extension affected the whole chain.

  8. Architecture and evolution of an Early Permian carbonate complex on a tectonically active island in east-central California

    USGS Publications Warehouse

    Stevens, Calvin H.; Magginetti, Robert T.; Stone, Paul

    2015-01-01

    The newly named Upland Valley Limestone represents a carbonate complex that developed on and adjacent to a tectonically active island in east-central California during a brief interval of Early Permian (late Artinskian) time. This lithologically unique, relatively thin limestone unit lies within a thick sequence of predominantly siliciclastic rocks and is characterized by its high concentration of crinoidal debris, pronounced lateral changes in thickness and lithofacies, and a largely endemic fusulinid fauna. Most outcrops represent a carbonate platform and debris derived from it and shed downslope, but another group of outcrops represents one or possibly more isolated carbonate buildups that developed offshore from the platform. Tectonic activity in the area occurred before, probably during, and after deposition of this short-lived carbonate complex.

  9. Geodetic component of the monitoring of tectonic and hydrogeological activities in Kopacki Rit Nature Park

    NASA Astrophysics Data System (ADS)

    Dapo, Almin; Pribicevic, Bosko

    2013-04-01

    Based on the European and global experience, the amplitude change in the structural arrangement caused by recent tectonic movements, can be most accurately determined by repeated precise GPS measurements on specially stabilized geodetic and geodynamic points. Because of these reasons, the GPS method to determine the movements on specially stabilized points in the Nature park Kopacki rit is also applied in this project. Kopacki rit Nature Park is the biggest preserved natural flooded area on the Danube. It is spread over 23 000 hectares between the rivers Danube and Drava and is one of the biggest fluvial wetland valleys in Europe. In 1993 it was listed as one of internationally valuable wetlands according to the Ramsar Convention. By now in Kopacki rit there have been sights of about 295 bird species, more than 400 species of invertebrates and 44 types of fish. Many of them are globally endangered species like, white tailed eagle, black stork and prairie hawk. It's not rare to come across some deer herds, wild boars or others. Today's geological and geomorphological relations in the Nature park Kopacki rit are largely the result of climate, sedimentary, tectonic and anthropogenic activity in the last 10,000 years. Unfortunately the phenomenon of the Kopacki rit Nature park is in danger to be over in the near future due to those and of course man made activities on the Danube river. It is trough scientific investigations of tectonic and hydrogeological activities that scientist from University of Zagreb are trying to contribute to wider knowledge and possible solutions to this problem. In the year 2009 the first GPS campaign was conducted, and the first set of coordinates of stabilized points was determined which can be considered zero-series measurements. In 2010 a second GPS campaign was conducted and the first set of movements on the Geodynamic Network of Kopacki Rit Nature Park was determined. Processing GPS measurements from 2009 and 2010 was carried out in a

  10. The Central-Western Mediterranean: Anomalous igneous activity in an anomalous collisional tectonic setting

    NASA Astrophysics Data System (ADS)

    Lustrino, Michele; Duggen, Svend; Rosenberg, Claudio L.

    2011-01-01

    The central-western Mediterranean area is a key region for understanding the complex interaction between igneous activity and tectonics. In this review, the specific geochemical character of several 'subduction-related' Cenozoic igneous provinces are described with a view to identifying the processes responsible for the modifications of their sources. Different petrogenetic models are reviewed in the light of competing geological and geodynamic scenarios proposed in the literature. Plutonic rocks occur almost exclusively in the Eocene-Oligocene Periadriatic Province of the Alps while relatively minor plutonic bodies (mostly Miocene in age) crop out in N Morocco, S Spain and N Algeria. Igneous activity is otherwise confined to lava flows and dykes accompanied by relatively greater volumes of pyroclastic (often ignimbritic) products. Overall, the igneous activity spanned a wide temporal range, from middle Eocene (such as the Periadriatic Province) to the present (as in the Neapolitan of southern Italy). The magmatic products are mostly SiO 2-oversaturated, showing calcalkaline to high-K calcalcaline affinity, except in some areas (as in peninsular Italy) where potassic to ultrapotassic compositions prevail. The ultrapotassic magmas (which include leucitites to leucite-phonolites) are dominantly SiO 2-undersaturated, although rare, SiO 2-saturated (i.e., leucite-free lamproites) appear over much of this region, examples being in the Betics (southeast Spain), the northwest Alps, northeast Corsica (France), Tuscany (northwest Italy), southeast Tyrrhenian Sea (Cornacya Seamount) and possibly in the Tell region (northeast Algeria). Excepted for the Alpine case, subduction-related igneous activity is strictly linked to the formation of the Mediterranean Sea. This Sea, at least in its central and western sectors, is made up of several young (< 30 Ma) V-shaped back-arc basins plus several dispersed continental fragments, originally in crustal continuity with the European

  11. A detection method of subrecent to recent tectonic activity in the anticlinal system of the northern Negev, Israel

    SciTech Connect

    Zilberman, E.; Wachs, D. )

    1988-02-01

    Geomorphological and geophysical methods combined with borehole information were employed to search for possible subrecent small-scale vertical movement along the anticlinal fold belt of the central Negev, Israel. Such tectonic deformation might indicate displacement on the buried reverse faults underneath the anticlines. Variations in the thickness of the alluvial fill in the study area, which are in accordance with the fold structures, could be an indication of recent folding activity along the anticlinal system. In order to detect these thickness variations in the alluvial fill, seismic refraction and electrical resistivity measurements were carries out along the valley of Nahal Besor, which crosses the anticlinal belt. The thickness variations of the alluvial fill along the valley were not found to indicate any significant tectonic movement along the anticlines during the Pleistocene. The thickest alluvium was found overlying a karst bedrock, hence karst relief is suggested to be responsible for these variations.

  12. Holocene canyon activity under a combination of tidal and tectonic forcing

    NASA Astrophysics Data System (ADS)

    Mountjoy, Joshu; Micallef, Aaron; Stevens, Craig; Stirling, Mark

    2013-04-01

    The majority of submarine canyon systems that are active during sea level highstands are coupled to terrestrial or littoral sediment transport systems (e.g. high sediment-yield rivers, wave-base sediment disturbance). However, non-coupled canyon systems can also exhibit sedimentary activity. Characterising the nature, origin, and spatial and temporal influence of the processes responsible for this sedimentary activity is important to understand the extent of sediment and carbon transfer to the deep sea, the impact of sedimentary flows on biological colonisation and diversity, and the control of recent seafloor processes on canyon morphology. The Cook Strait canyon system, between the North and South islands of New Zealand, is a large (1800 km2), multi-branching, shelf-indenting canyon on an active subduction margin. The canyon comes within 1 km of the coast, but does not intercept fluvial or littoral sediment systems and is therefore defined as a non-terrestrially-coupled system. Sediment transport on the continental shelf, associated with a strong tidal stream, and seafloor disturbance related to numerous high-activity faults is known from previous studies. Little is known, however, about the rates of sedimentary activity in the canyon and the processes driving it. The canyon system therefore provides an excellent study area for understanding sediment transport in a non-coupled submarine canyon system. Analysis of EM300 multibeam bathymetry, gravity cores, 3.5 kHz seismic reflection profiles, camera and video transects and current meter data reveals a system where oceanographic (tidal) and tectonic (earthquake) processes are moving sediment from the continental shelf, through the upper canyon, and finally to the deep ocean. Sediment accumulation rates may reach several mm/yr in the upper canyons, with data suggesting minimum rates of 0.5 mm/yr. We demonstrate that tidal currents are sufficient to mobilise fine to medium sand around and within the upper canyon

  13. Recent tectonic activity on Pluto driven by phase changes in the ice shell

    NASA Astrophysics Data System (ADS)

    Hammond, Noah P.; Barr, Amy C.; Parmentier, Edgar M.

    2016-07-01

    The New Horizons spacecraft has found evidence for geologic activity on the surface of Pluto, including extensional tectonic deformation of its water ice bedrock see Moore et al. (2016). One mechanism that could drive extensional tectonic activity is global surface expansion due to the partial freezing of an ocean. We use updated physical properties for Pluto and simulate its thermal evolution to understand the survival of a possible subsurface ocean. For thermal conductivities of rock less than 3 W m-1 K-1, an ocean forms and at least partially freezes, leading to recent extensional stresses in the ice shell. In scenarios where the ocean freezes and the ice shell is thicker than 260 km, ice II forms and causes global volume contraction. Since there is no evidence for recent compressional tectonic features, we argue that ice II has not formed and that Pluto's ocean has likely survived to present day.

  14. Applications of Morphochronology to the Active Tectonics of Tibet

    SciTech Connect

    Ryerson, F J; Tapponnier, P; Finkel, R C; Meriaux, A; der Woerd, J V; Lasserre, C; Chevalier, M; Xiwei, X; Haibing, L; King, G P

    2005-01-28

    The Himalayas and the Tibetan Plateau were formed as a result of the collision of India and Asia, and provide an excellent opportunity to study the mechanical response of the continental lithosphere to tectonic stress. Geophysicists are divided in their views on the nature of this response advocating either (1) homogeneously distributed deformation with the lithosphere deforming as a fluid continuum or (2) deformation is highly localized with the lithosphere that deforms as a system of blocks. The resolution of this issue has broad implications for understanding the tectonic response of continental lithosphere in general. Homogeneous deformation is supported by relatively low decadal, geodetic slip-rate estimates for the Altyn Tagh and Karakorum Faults. Localized deformation is supported by high millennial, geomorphic slip-rates constrained by both cosmogenic and radiocarbon dating on these faults. Based upon the agreement of rates determined by radiocarbon and cosmogenic dating, the overall linearity of offset versus age correlations, and on the plateau-wide correlation of landscape evolution and climate history, the disparity between geomorphic and geodetic slip-rate determinations is unlikely to be due to the effects of surface erosion on the cosmogenic age determinations. Similarly, based upon the consistency of slip-rates over various observation intervals, secular variations in slip-rate appear to persist no longer than 2000 years and are unlikely to provide reconciliation. Conversely, geodetic and geomorphic slip-rate estimates on the Kunlun fault, which does not have significant splays or associated thrust faults, are in good agreement, indicating that there is no fundamental reason why these complementary geodetic and geomorphic methods should disagree. Similarly, the geodetic and geomorphic estimates of shortening rates across the northeastern edge of the plateau are in reasonable agreement, and the geomorphic rates on individual thrust faults demonstrate

  15. Middle proterozoic tectonic activity in west Texas and eastern New Mexico and analysis of gravity and magnetic anomalies

    SciTech Connect

    Adams, D.C.; Keller, G.R. )

    1994-03-01

    The Precambrian history of west Texas and eastern New Mexico is complex, consisting of four events: Early Proterozoic orogenic activity (16309-1800 Ma), formation of the western granite-rhyolite province (WGRP) (1340-1410 Ma), Grenville age tectonics (1116-1232 Ma), and middle Proterozoic extension possibly related to mid-continent rifting (1086-1109 Ma). Pre-Grenville tectonics, Grenville tectonics, and mid-continent rifting are represented in this area by the Abilene gravity minimum (AGM) and bimodal igneous rocks, which are probably younger. We have used gravity modeling and the comparison of gravity and magnetic anomalies with rock types reported from wells penetrating Precambrian basement to study the AGM and middle Proterozoic extension in this area. The AGM is an east-northeast-trending, 600 km long, gravity low, which extends from the Texas-Oklahoma border through the central basin platform (CBP) to the Delaware basin. This feature appears to predate formation of the mafic body in the CBP (1163 Ma) and is most likely related to Pre-Grenville tectonics, possibly representing a continental margin arc batholith. Evidence of middle Proterozoic extension is found in the form of igneous bodies in the CBP, the Van Horn uplift, the Franklin Mountains, and the Sacramento Mountains. Analysis of gravity and magnetic anomalies shows that paired gravity and magnetic highs are related to mafic intrusions in the upper crust. Mapping of middle Proterozoic igneous rocks and the paired anomalies outlines a 530 km diameter area of distributed east-west-oriented extension. The Debaca-Swisher terrain of shallow marine and clastic sedimentary rocks is age correlative with middle Proterozoic extension. These rocks may represent the lithology of possible Proterozoic exploration targets. Proterozoic structures were reactivated during the Paleozoic, affecting both the structure and deposition in the Permian basin.

  16. Active tectonics in Central Italy: constraints from surface wave tomography and source moment tensor inversion

    NASA Astrophysics Data System (ADS)

    Chimera, G.; Aoudia, A.; Saraò, A.; Panza, G. F.

    2003-08-01

    We investigate the lithosphere-asthenosphere structure and active tectonics of Central Italy, with emphasis on the Umbria-Marche area, by means of surface wave tomography and seismic moment tensor inversion. The data include: a large number of short period local and regional group velocity measurements sampling the Umbria-Marche Apennines and the Adria margin, respectively; incorporation of published phase velocity measurements sampling Italy and surroundings; results from deep seismic soundings which go through the Umbria-Marche area. The local group velocity maps, covering the area reactivated by the 1997-1998 Umbria-Marche earthquake sequence, suggest an intimate relationship between the lateral earth structure variations and the distribution of the active fault systems and related sedimentary basins. The upper crustal models reveal the importance of inherited compressional tectonics on the recent extensional deformation and associated seismic activity. Source inversion studies of the main events of the 1997 earthquake sequence show the dominance of normal faulting mechanisms, whereas selected aftershocks between the fault segments, at the step-over, reveal that the prevailing deformation is of strike-slip faulting type. At the regional scale, the crust exhibits clear layering and varies in thickness from about 25 km below the Tuscan Metamorphic Complex (TMC), to about 30 km below the Val Tiberina extensional thick sedimentary basin and reaches about 35 km below the Umbria-Marche geological domain (UMD). The lithospheric mantle (lid) is thin (about 30 km) below TMC, while it is about 70 km thick below UMD. A lithospheric root about 120 km wide, between the TMC and UMD, reaches a depth of at least 130 km. A low-velocity zone, defined mantle wedge ( VS less than 4.2 km/s) in the uppermost mantle overlying the high velocity lid is detached. This wedge is about 20 km thick and decouples the underlying lid from the crust. The retrieved crust and upper mantle

  17. Migration of the Ganga River and development of cliffs in the Varanasi region, India during the late Quaternary: Role of active tectonics

    NASA Astrophysics Data System (ADS)

    Shukla, U. K.; Srivastava, P.; Singh, I. B.

    2012-10-01

    The lithofacies constitution of unconsolidated sediments exposed in Ramnagar cliff indicates sedimentation in sinuous channels, associated flood plain areas and ponds that were developed within the Ganga River valley. The Khadar surface represents a raised river valley terrace into which the main river channel along with its narrow floodplain is incised. Ramnagar cliff section has revealed a variety of deformation structures that indicate repeated tectonic activity in the area. Important tectonic features exposed by the cliff section are reverse faults, folds, cracks filled with sparry calcite and soft sediment structures indicating liquefaction of sediments affected by faulting and folding. Optically stimulated luminescence (OSL) dating of sediments and field relationships of tectonic elements indicate that the Ganga River migrated near to Varanasi 40 ka following a tectonic event in the area. Since then, it meandered freely within its valley until 7 ka when another tectonic event took place and Ramnagar cliff was raised to its present heights. The cliff surface was degraded by gulling activity for about 4000 years before it was occupied by man at around 3000 years BP.

  18. GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany)

    PubMed Central

    Berberich, Gabriele; Schreiber, Ulrich

    2013-01-01

    Simple Summary In a 1.140 km² study area of the volcanic West Eifel, approx. 3,000 Red Wood Ant (RWA; Formica rufa-group) mounds had been identified and correlated with tectonically active gas-permeable faults, mostly strike-slip faults. Linear alignment of RWA mounds and soil gas anomalies distinctly indicate the course of these faults, while clusters of mounds indicate crosscut zones of fault systems, which can be correlated with voids caused by crustal block rotation. This demonstrates that RWA are bioindicators for identifying active fault systems and useful where information on the active regime is incomplete or the resolution by technical means is insufficient. Abstract In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO2, Helium, Radon and H2S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H2S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel

  19. Evidence for a major, tectonically active structure beneath the coastal plain of North and South Carolina

    SciTech Connect

    Marple, R.T.; Talwani, P. . Geology Dept.); Olson, O.

    1994-03-01

    Evaluation of Landsat imagery, aerial photography, potential field data, and topographic maps have revealed a linear, [approximately]400-km-long, NNE-trending zone in the coastal plain of North and South Carolina. This zone is composed of subtle topographic highs, aeromagnetic anomalies, and in some locations mapped and inferred faults. It is also associated with a zone of river anomalies (ZRA). Various data suggest that the ZRA may be associated with tectonic activity on a large right-lateral strike-slip fault system. The ZRA in the South Carolina coastal plain is defined by an [approximately]15-km-wide NNE-trending zone that crosses NW-SE-flowing rivers. Along this zone the rivers are characterized by river bends that are convex toward the NNE, incised channels, changes in river patterns, and convex-upward longitudinal profiles. In the coastal plain and eastern Slate Belt of North Carolina the ZRA (width yet to be determined) displays a slightly more northeasterly trend that is highlighted by linear aeromagnetic anomalies and right-lateral offsets of larger rivers crossing its trend. This feature is not traceable across the southern flank of the Cape Fear Arch and north of this area the ZRA's trend is offset [approximately]15 km toward the east (right step geometry) from that of the ZRA in South Carolina. Analyses of geologic and geophysical data further indicate that these two zones may be the result of ongoing tectonic uplift along a NNE-trending right-lateral strike-slip fault zone possibly associated with recent seismicity near Charleston.

  20. Mapping Active Faults and Tectonic Geomorphology offshore central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Watt, J. T.; Hart, P. E.; Sliter, R. W.; Wong, F. L.

    2009-12-01

    In June 2008, and July 2009, the USGS conducted two high-resolution, marine, seismic-reflection surveys across the continental shelf and upper slope between Piedras Blancas and Point Sal, central California, in order to better characterize regional earthquake sources. More than 1,300 km of single-channel seismic data were acquired aboard the USGS R/V Parke Snavely using a 500-joule mini-sparker source fired at a 0.5-second shot interval and recorded with a 15-meter streamer. Most tracklines were run perpendicular to the coast at 800-meter spacing, extending from the nearshore (~ 10-15 m water depth) to as far as 20 km offshore. Sub-bottom imaging varies with substrate, ranging from outstanding (100 to 150 m of penetration) in inferred Quaternary shallow marine, shelf and upper slope deposits to poor (0 to 10 m) in the Mesozoic basement rocks. Marine magnetic data were collected simultaneously on this survey, and both data sets are being integrated with new aeromagnetic data, publicly available industry seismic-reflection data, onshore geology, seismicity, and high-resolution bathymetry. Goals of the study are to map geology, structure, and sediment distribution; to document fault location, length, segmentation, shallow geometry and structure; and to identify possible sampling targets for constraining fault slip rates, earthquake recurrence, and tsunami hazard potential. The structure and tectonic geomorphology of the >100-km-long, right-lateral, Hosgri fault zone and its connections to the Los Osos, Pecho, Oceano and other northwest-trending inboard faults are the focus of this ongoing work. The Hosgri fault forms the eastern margin of the offshore Santa Maria basin and coincides in places with the outer edge of the narrow (5- to 15-km-wide), structurally complex continental shelf. The Hosgri is imaged as a relatively continuous, vertical fault zone that extends upward to the seafloor; varies significantly and rapidly along strike; and incorporates numerous

  1. Igneous activity, metamorphism, and deformation in the Mount Rogers area of SW Virginia and NW North Carolina: A geologic record of Precambrian tectonic evolution of the southern Blue Ridge Province

    USGS Publications Warehouse

    Tollo, Richard P.; Aleinikoff, John N.; Mundil, Roland; Southworth, C. Scott; Cosca, Michael A.; Rankin, Douglas W.; Rubin, Allison E.; Kentner, Adrienne; Parendo, Christopher A.; Ray, Molly S.

    2012-01-01

    Mesoproterozoic basement in the vicinity of Mount Rogers is characterized by considerable lithologic variability, including major map units composed of gneiss, amphibolite, migmatite, meta-quartz monzodiorite and various types of granitoid. SHRIMP U-Pb geochronology and field mapping indicate that basement units define four types of occurrences, including (1) xenoliths of ca. 1.33 to ≥1.18 Ga age, (2) an early magmatic suite including meta-granitoids of ca. 1185–1140 Ma age that enclose or locally intrude the xenoliths, (3) metasedimentary rocks represented by layered granofels and biotite schist whose protoliths were likely deposited on the older meta-granitoids, and (4) a late magmatic suite composed of younger, ca. 1075–1030 Ma intrusive rocks of variable chemical composition that intruded the older rocks. The magmatic protolith of granofels constituting part of a layered, map-scale xenolith crystallized at ca. 1327 Ma, indicating that the lithology represents the oldest, intact crust presently recognized in the southern Appalachians. SHRIMP U-Pb data indicate that periods of regional Mesoproterozoic metamorphism occurred at 1170–1140 and 1070–1020 Ma. The near synchroneity in timing of regional metamorphism and magmatism suggests that magmas were emplaced into crust that was likely at near-solidus temperatures and that melts might have contributed to the regional heat budget. Much of the area is cut by numerous, generally east- to northeast-striking Paleozoic fault zones characterized by variable degrees of ductile deformation and recrystallization. These high-strain fault zones dismember the terrane, resulting in juxtaposition of units and transformation of basement lithologies to quartz- and mica-rich tectonites with protomylonitic and mylonitic textures. Mineral assemblages developed within such zones indicate that deformation and recrystallization likely occurred at greenschist-facies conditions at ca. 340 Ma.

  2. The River Network, Active Tectonics and the Mexican Subduction Zone, Southwest Mexico

    NASA Astrophysics Data System (ADS)

    Gaidzik, K.; Ramirez-Herrera, M. T.; Kostoglodov, V.; Basili, R.

    2014-12-01

    Rivers, their profiles and network reflect the integration of multiple processes and forces that are part of the fundamental controls on the relief structure of mountain belts. The motivation of this study is to understand active tectonic processes in the forearc region of subduction zones, by distinguishing evidence of active deformation using the river network and topography. To this end, morphotectonic and structural studies have been conducted on fifteen drainage basins on the mountain front, parallel to the Mexican subduction zone, where the Cocos plate underthrusts the North American plate. The southwest - northeast Cocos plate subduction stress regime initiated ca. 20 MA. NE-SW to NNE-SSW normal faults as well as sub-latitudinal to NW-SE strike-slip faults (both dextral and sinistral) constitute the majority of mesofaults recorded in the field within the studied drainage basins. Occasionally dextral N-S strike-slip faults also occur. The stress tensor reconstruction suggests two main evolution stages of these faults: 1) the older is dominated by a NW-SE to WNW-ESE extensional regime and 2) the younger is a transcurrent regime, with NNE-SSW σ1 axis. The drainage pattern is strongly controlled by tectonic features, whereas lithology is only a subordinate factor, with only one exception (Petatlán river). Generally, major rivers flow from north to south mainly through NE-SW and NNE-SSW normal faults, and/or sub-longitudinal dextral (also locally sinistral) strike-slip faults. In the central and eastern part of the studied area, rivers also follow NW-SE structures, which are generally normal or sinistral strike-slip faults (rarely reverse). In most cases, local deflections of the river main courses are related to sub-latitudinal strike-slip faults, both dextral and sinistral. Within the current stress field related to the active Cocos subduction, both normal and strike-slip fault sets could be reactivated. Our analysis suggests that strike-slip faults, mainly

  3. The early Paleozoic sedimentary-tectonic evolution of the circum-Mangar areas, Tarim block, NW China: Constraints from integrated detrital records

    NASA Astrophysics Data System (ADS)

    Dong, Shunli; Li, Zhong; Jiang, Lei

    2016-07-01

    The Mangar depression, located in the eastern part of the Tarim basin, had deposited extremely-thick lower Paleozoic sediments, which yields great scientific value and hydrocarbon resource potential. Due to the lack of enough outcrop and core studies, many issues, e.g., early Paleozoic geographical evolution, basin nature and tectonic affinity, are still poorly understood. In this study, we selected circum-Mangar areas (i.e., the South Quruqtagh, Tabei and Tazhong areas), and carried out comprehensive detrital provenance analysis including detrital modal analysis, heavy mineral and trace element analysis, and detrital zircon U-Pb dating on the Middle-Upper Ordovician and Silurian sandstones. The results show that Upper Ordovician-Lower Silurian detrital provenances of the South Quruqtagh and Tabei areas were primarily derived from the intracontinental uplifts in Tarim. Meanwhile, Upper Silurian detrital provenances of the above two areas were mainly derived from the mix of intracontinental uplifts and continental-margin arcs. Dramatic Late Silurian provenance-change suggests the evident tectonic transition of the northern Tarim margin, which is the opening of the South Tianshan back-arc oceanic basin. Combining the previous studies, an integral redefinition model for the Mangar depression has been made. The evolution process of the Mangar depression could be divided into four stages: graben stage (late Neoproterozoic), transitional stage (Cambrian to Middle Ordovician), downwarp stage (Late Ordovician to Early Silurian) and extinction stage (Late Silurian). Hence, the Mangar depression evolved as an aulacogen. Significantly, the evolutional scenario of the Mangar aulacogen was consistent with that of the North Altyn Tagh and the North Qilian, suggesting that the Mangar aulacogen was involved mainly in the Proto-Tethys tectonic realm south to the Tarim block. However, the Late Silurian tectonic activity in the northern Tarim margin did produce massive detrital

  4. Investigating Geothermal Activity, Volcanic Systems, and Deep Tectonic Tremor on Akutan Island, Alaska, with Array Seismology

    NASA Astrophysics Data System (ADS)

    Haney, M. M.; Prejean, S. G.; Ghosh, A.; Power, J. A.; Thurber, C. H.

    2012-12-01

    In addition to hosting one of the most active volcanoes in the Aleutian Arc, Akutan Island, Alaska, is the site of a significant geothermal resource within Hot Springs Bay Valley (HSBV). We deployed 15 broadband (30 s to 50 Hz) seismometers in and around HSBV during July 2012 as part of an effort to establish a baseline for background seismic activity in HSBV prior to geothermal production on the island. The stations recorded data on-site and were retrieved in early September 2012. Additional targets for the array include the tracking of deep tectonic tremor known to occur within the Aleutian subduction zone and the characterization of volcano-tectonic (VT) and deep long period (DLP) earthquakes from Akutan Volcano. Because 13 of the stations in the array sit within an area roughly 1.5 km by 1.5 km, we plan to apply methods based on stacking and beamforming to analyze the waveforms of extended signals lacking clear phase arrivals (e.g., tremor). The average spacing of the seismometers, roughly 350 m, provides sensitivity to frequencies between 2-8 Hz. The stacking process also increases the signal-to-noise ratio of small amplitude signals propagating across the array (e.g., naturally occurring geothermal seismicity). As of August 2012, several episodes of tectonic tremor have been detected in the vicinity of Akutan Island during the array deployment based on recordings from nearby permanent stations operated by the Alaska Volcano Observatory (AVO). This is the first small-aperture array deployed in the Aleutian Islands and the results should serve as a guide for future array deployments along the Aleutian Arc as part of the upcoming EarthScope and GeoPRISMS push into Alaska. We demonstrate the power of array methods based on stacking at Akutan Volcano using a sequence of DLP earthquakes from June 11, 2012 that were recorded on the permanent AVO stations. We locate and characterize the lowest frequency portion of the signals at 0.5 Hz. At these low frequencies, the

  5. K-T magmatism of western Rajasthan, India: Manifestation of Reunion plume activity or extensional lithospheric tectonics?

    NASA Astrophysics Data System (ADS)

    Sharma, K.

    2004-12-01

    A number of alkaline plutons have been recorded at the K-T (Cretaceous-Tertiary) boundary in western Rajasthan, India. Significant magmatism occurred at Mundwara, Barmer, Sarnu-Dandali and Tavider. The evolution of the Cambay-Sanchor-Barmer rift during the K-T period resulted in these alkaline complexes at the rift margins. Sedimentary basins are developed in the Barmer and Jaiselmer regions. The magmatism of Mundwara and Sarnu-Dandali is dated at 68.50 Ma and considered as an early pulse of Deccan volcanism. Several workers correlated K-T sedimentary basin evolution, magmatism and other tectonic features of western Rajasthan with the Reunion plume-interaction in the northwestern Indian shield. Alkaline igneous complexes along the rift from the southern part are reported from Phenai Mata, Amba Dongar and Seychelles. The Seychelles was part of the northwestern Indian shield prior to Deccan volcanism. The Mundwara igneous complex represents three distinct circular plutonic bodies - Toa, Mer and Mushala, which are situated in the periphery of an area three kilometers in radius. Besides these, there are numerous concentric and radial dykes of lamprophyre, carbonatite, dolerite and amphibolite. All these three bodies represent different phases of intrusion and are not similar to each other. The alkaline rocks of Sarnu-Dandali occur as dykes and isolated plugs in the desert sand. Carbonatite dykes are also reported from southeast of Barmer. The Tavider outcrop is devoid of any plutonic rock and consists of rhyolite, andesite and basalt. These rocks occur along the Precambrian Malani magmatic lineaments. The development of the Cambay-Sanchor-Barmer rift caused reactivation of Precambrian fractures and resulted in magmatism at the basin margin. The Gondwanaland fragmentation during the Mesozoic era caused extensional tectonics in the northwestern Indian shield. This led to the development of rift basins in Gujarat and western Rajasthan. Deccan volcanism, separation of the

  6. Glacier Ice Mass Fluctuations and Fault Instability in Tectonically Active Southern Alaska

    NASA Technical Reports Server (NTRS)

    SauberRosenberg, Jeanne M.; Molnia, Bruce F.

    2003-01-01

    Across southern Alaska the northwest directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska. This has led to high tectonic strain rates and dramatic topographic relief of more than 5000 meters within 15 km of the Gulf of Alaska coast. The glaciers of this area are extensive and include large glaciers undergoing wastage (glacier retreat and thinning) and surges. The large glacier ice mass changes perturb the tectonic rate of deformation at a variety of temporal and spatial scales. We estimated surface displacements and stresses associated with ice mass fluctuations and tectonic loading by examining GPS geodetic observations and numerical model predictions. Although the glacial fluctuations perturb the tectonic stress field, especially at shallow depths, the largest contribution to ongoing crustal deformation is horizontal tectonic strain due to plate convergence. Tectonic forces are thus the primary force responsible for major earthquakes. However, for geodetic sites located < 10-20 km from major ice mass fluctuations, the changes of the solid Earth due to ice loading and unloading are an important aspect of interpreting geodetic results. The ice changes associated with Bering Glacier s most recent surge cycle are large enough to cause discernible surface displacements. Additionally, ice mass fluctuations associated with the surge cycle can modify the short-term seismicity rates in a local region. For the thrust faulting environment of the study region a large decrease in ice load may cause an increase in seismic rate in a region close to failure whereas ice loading may inhibit thrust faulting.

  7. Geomorphic impacts of active tectonics on a river course, the case of Klissoura gorge, central Greece.

    NASA Astrophysics Data System (ADS)

    Tsanakas, Konstantinos; Fubelli, Giandomenico; Karymbalis, Efthimios

    2014-05-01

    The delicate balance of the natural processes within the river systems can be easily tipped making them very sensitive to changes occurring on the earth surface. Fluvial systems are therefore profoundly influenced by endogenic processes such as active tectonics as well as global sea level fluctuations following the climatic variations during the Quaternary. This study deals with the geomorphological evolution of the broader area of the abandoned gorge of Klissoura which is located in central Greece. This 130 m deep and roughly 3 km long gorge is a characteristic example of an old drainage course preserved on the footwall blocks of two normal faults which confine both outlets of the deeply incised valley. The gorge has formed by a river that once had a N-S flow direction discharging into the Gulf of Patras. Acheloos River and the much smaller Ermitza Remma Stream are the two recent primary watercourses which drain the area close to the abandoned gorge. Both the dimensions and morphological characteristics of the abandoned deep valley indicate that the gorge has formed by a large river with high discharge in order to incise into the limestone bedrock. In order to investigate the tectonic constrains and determine the geomorphic and climatic processes that compelled the lower reaches of Acheloos River to abandon the gorge and find an outlet following its present course a GIS based analysis at a scale of 1:50.000 was applied in the drainage basin of Acheloos River. Additionally, to reconstruct the palaeolandscape and the earth surface processes, a detailed morphometric and geomorphic analysis of the abandoned gorge was also performed at a scale of 1:5.000 coupled with field observations and stratigraphic analysis of the deposits outcropping on the valley sides within the gorge as well as on both outlets. The geomorphic analysis led to the conclusion that the primary course of the gorge abandonment and diversion and reverse of the drainage is the uplift of the footwall

  8. Active tectonic and magmatic processes beneath Long Valley Caldera, eastern California: an overview ( USA).

    USGS Publications Warehouse

    Hill, D.P.; Bailey, R.A.; Ryall, A.S.

    1985-01-01

    Geological, chronological, and structural studies of the Long Valley-Mono/Inyo Craters area document a long history of related volcanic eruptions and earthquakes controlled by regional extensional tectonics of the Basin and Range province. This activity has persisted for hundreds of thousands of years and is likely to continue. The Long Valley magma chamber had a volume approaching 3000 km3 prior to its climatic caldera-forming eruption 0.7 ma but has been reduced to less than a third of this volume by cooling, eruption, and crystallization. Although current unrest is concentrated in the S moat of Long Valley caldera, the Inyo/Mono Craters probably hold a greater potential for producing an eruption in the foreseeable future. The Inyo/Mono Craters have erupted at 500-year intervals over the past 2000-3000 years, whereas the Long Valley magma chamber has erupted at about 200,000-year intervals over the past 700,000 years. In either case, a major earthquake near the caldera could strongly influence the course of volcanic activity.-from Authors

  9. Cenozoic Plate tectonic history of the northern Venezuela-Trinidad Area

    NASA Astrophysics Data System (ADS)

    Erlich, Robert N.; Barrett, S. F.

    1990-02-01

    Geological and geophysical data, coupled with recent plate tectonic reconstructions, suggest that the Cenozoic geologic history of the northern Venezuela-Trinidad area has been dominated by strike-slip displacement of discrete crustal blocks. Allochthonous terranes within the area include metavolcanic rocks of the Cretaceous Villa de Cura Group and metamorphic rocks of the Precambrian to Cretaceous Cordillera de la Costa. A relatively competent crustal block (Margarita Block) is defined by an outline around the metamorphic basement of Margarita Island, the Araya/Paria peninsula, the Northern Range of Trinidad, and Tobago Island. Reconstruction of the Margarita Block to its original position requires at least partial closure of the Falcon Basin, closure of the Bonaire and Cariaco basins, and restoration of about 50 km of motion on both the Oca and Bocono faults. Post middle Eocene eastward translation of the Caribbean plate caused eastward motion of the Margarita Block. A minor change in relative plate motion during the late Oligocene or early Miocene produced a right step in the Moron fault, forming the Cariaco pull-apart basin and El Pilar fault zone. Maximum offset on El Pilar fault is estimated to be no more than 125 km, though displacement along the entire fault zone may have been greater. Transpressional stresses between the Caribbean plate and northern South America caused folding of the Serrania del Interior of Venezuela and the Central Range of Trinidad. Eastward migration of transpressional stresses at the southeastern corner of the Caribbean-South American plate boundary is being accommodated by formation of oblique thrusts, transpressive anticlines, and downwarping of the crust. Bouguer gravity data suggest that Jurassic-aged Atlantic oceanic crust is being depressed as the Caribbean plate expands into the Demerara Plateau area. This study suggests that the faults and transtensional/transpressional/compressional structures identified in this study are

  10. Seismic Swarms at Paricutin Volcano Area. Magmatic Intrusion or Tectonic Seismicity?

    NASA Astrophysics Data System (ADS)

    Pinzon, J. I.; Nunez-Cornu, F. J.; Escudero, C. R.; Rowe, C. A.

    2014-12-01

    We relocate a seismic swarm with more than 700 earthquakes that took place between May and June 2006 in the Paricutin volcano area, Mexico inside of the Michoacan monogenetic volcanic field. This seismic swarm was recorded by the project "Mapping the Riviera Subduction Zone" (MARS), a temporary seismic network that was installed in the states of Jalisco, Colima and Michoacán between January 2006 and June 2007. Previously seismic swarms in the area were reported in the years of 1997, 1999 and 2000. For one that took place in the year of 1997 the Servicio Sismologico Nacional deployed a local network in the area, they conclude that the source of the seismicity was tectonic with depths between 18 and 12 km. The episodes of 1999 and 2000 were reported as similar to the 1997 swarm. A previous analysis of the 2006 swarm concludes that the depth of seismicity migrates from 9 to 5 km and was originated by a magmatic intrusion. We did a relocation of this swarm reading all the events and using Hypo71 and the P-wave velocity model used by the Jalisco Seismic and Acelerometric Network; a waveform analysis using cross-correlation method was also carried out. We obtained 15 earthquakes families with a correlation factor equal or greater than 0.79 and composed focal mechanism for each family. These families present a migration in depth beginning at 16 km and ended at 9 km. Our results agrees with a magmatic intrusion, but not so shallow as the previous study of the 2006 swarm.

  11. Fission-track tectonic studies of the Transantarctic Mountains, Beardmore Glacier area

    SciTech Connect

    Fitzgerald, P.G.

    1986-01-01

    The Transantarctic Mountains are a major transcontinental range stretching for some 4000 kilometers, varying from 200-400 kilometers in width, and having elevations up to 4500 meters. The uplift and formation of the Transantarctic Mountains have always been something of an enigma, but recent apatite fission-track analysis is providing important new information not only about their uplift history but also about the implications of that uplift history for the glacial history of Antarctica as a whole. The main field objective of this project was to collect samples for fission-track analysis to determine the timing and rate of uplift of the Transantarctic Mountains and measure relative vertical displacements across faults within the range. Results from southern Victoria Land indicate that uplift of the Transantarctic Mountains was initiated at about 50 million years ago and since that time the mountains have undergone some 5 kilometers of uplift at an average rate of 100 meters per million years. It is important to realize, however, that this is an average rate and may well conceal pulses of faster and slower uplift or even periods of subsidence. The amount of uplift across the mountain range is differential; from the axis of maximum uplift about 30 kilometers inland of the Victoria Land coast, the mountains dip gently westward under the polar ice cap. The study was extended to the Beardmore Glacier area to see whether the uplift history and tectonics varies from that observed in southern Victoria Land.

  12. Tectonic and structural setting of the northeastern central Gulf of Suez area using aeromagnetic data

    NASA Astrophysics Data System (ADS)

    Zahra, Hesham Shaker; Nakhla, Adel Mokhles

    2016-03-01

    Cumulative qualitative and quantitative analysis of the filtered regional and residual magnetic components of the northeastern central area of the Gulf of Suez, as well as images of the second vertical derivatives of the reduced to the northern magnetic pole map of the total magnetic intensity field images, supplemented with the available geologic information, enabled the precise delineation of the detailed structural configuration of the basement complex, which consequently illustrated the structural deformational pattern of the overlying sedimentary succession. The basement tectonic map reflects a series of N-S to NNW-SSE oriented belts of high and low basement structures. These structures are interrupted by a set of NE-SW crossing diagonal faults having varying throws and creating promising blocks for exploration. An often remarkable correlation between the reduced to the magnetic pole map and the basement relief map is noted, in particular the outline of various oil fields. A larger number of the tilted fault blocks and basement culminations have been outlined and numerous interesting exploration prospects are indicated, which appear to warrant further follow up investigation.

  13. Continental tectonics in the aftermath of plate tectonics

    NASA Technical Reports Server (NTRS)

    Molnar, Peter

    1988-01-01

    It is shown that the basic tenet of plate tectonics, rigid-body movements of large plates of lithosphere, fails to apply to continental interiors. There, buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is discussed. Future areas of investigation are addressed.

  14. Microearthquakes and tectonics in an active back-arc basin: the Lau Basin

    NASA Astrophysics Data System (ADS)

    Eguchi, Takao; Fujinawa, Yukio; Ukawa, Motoo

    1989-09-01

    An Ocean Bottom Seismograph (OBS) array was deployed for 20-22 days in late 1984 to investigate the precise locations of microearthquakes and their tectonic implications for active back-arc opening in the northern Lau Basin. Using P- and S-wave arrival times from four or more OBSs, the hypocenters of ˜ 300 shallow earthquakes were located with a high confidence level. The magnitudes of most OBS-located earthquakes were estimated to be less than four. In the northern half of the survey area, a narrow, linear zone of microearthquakes, trending NNW-SSE, has been identified. The northern part of the narrow seismic zone is within a central axial depression at the southern end of the Peggy Ridge. Further south, the trend of the seismic zone becomes more N-S. The narrow seismic zone seems to be composed of at least six seismic segments, offset by short aseismic zones. Most of the seismic segments trend NNW-SSE, suggesting a system of left-stepping en echelon spreading ridges, where the spreading ridge segment is seismically inactive and the transform fault is active. The spreading ridges appear to strike N-S or NNW-SSE, but the direction of the back-arc opening is considered to be NW-SE. No hypocenters were located with a high level of precision in the area south of latitude 18°S, except a small isolated zone of shallow earthquakes at the southeastern part of the survey area. We suggest that the shallow earthquakes in this isolated seismic zone were intraplate events in the Tonga platelet. This platelet is separated from the major Indo-Australian plate by the back-arc opening system in the Lau Basin.

  15. Erosional flux from tectonically active landscapes: Case studies from Southern Italy

    NASA Astrophysics Data System (ADS)

    Roda-Boluda, Duna; D'Arcy, Mitch; Whittaker, Alex; Allen, Philip; Gheorghiu, Delia; Rodes, Angel

    2016-04-01

    Erosion and sediment supply are fundamentally important controls on landscape evolution, governing the denudation of relief, the stratigraphy deposited in basins, and the ultimate destruction of orogens. However, quantifying the rates, timescales, and predominant processes of erosion remains a major challenge in many tectonically active areas. Here, we use Southern Italy as a case study to demonstrate how these challenges can be overcome. We present 15 new 10Be catchment-averaged erosion rates, for systems distributed along 5 active normal faults for which we have excellent constraints on throw rates along strike and uplift history. These footwall catchments have a total relief of up to 1800 m and throw rates up to 1.4 mm/yr. We show that sediment supply estimates based on the 10Be erosion rates agree well with sediment supply predictions based on the fault throw profiles. Our results suggest that about 80% of the material uplifted by the faults is being eroded at a similar magnitude to the fault throw rates, offering new insights into the topographic balance of uplift and erosion in this area. These findings imply that active normal faulting is the primary control on sediment supply in Southern Italy. Our field observations suggest that landslides are an important source of sediment in our study area, and are largely driven by incision in response to fault activity. Using a field-calibrated landslide inventory, we estimate landslide-derived sediment flux for our sampled catchments. These estimates correlate well with total sediment flux estimates, demonstrating quantitatively that landslides must be a major source of sediment. Their erosional signal is adequately captured by the 10Be analyses most likely because of the high frequency of small landslides and their high spatial density in these catchments (typically >10% of the total area), which ensures sufficient sediment mixing. Finally, we use our results to calibrate the BQART model of sediment supply, enabling

  16. Taiwan: a perfect field trip to study active tectonics and erosion processes

    NASA Astrophysics Data System (ADS)

    Bigot-Cormier, Florence; Beauval, Véronique; Martinez, Claire-Marie; Seyeux, Jana

    2014-05-01

    Taiwan is located at the boundary between the Philippine Sea Plate to the East and the Eurasian Plate to the West. This plate boundary is rather complex since it comprises two subduction zones of reverse polarities. Due to this specific geodynamic context, this field is a perfect area to answer the French program in 5th grade (erosion processes) and 4th grade (active tectonics) in Earth Science class. That's why for the second year, students from the Lycée Français de Shanghai (LFS) in 4th grade will go for a 4-day field trip to discover volcanoes (in the Yangminshan National Park) and para-seismic constructions in the 101 Tower at Taipei. It will remind them the program of their previous class (5ème) through the visit of Yehliu Geographic Park and some other areas in the North of the Island where they will be able to observe different erosion processes (wind or water) carving the landscape. The aim of this field trip is first to show them that Earth Sciences cannot be studied only in class but also on the field to get a better understanding of the processes. In this manner, after having understood the internal thermal system of our Earth in class, they will see its manifestations on the surface of the Earth, by seeing an active explosive volcano with gas ejection, specific mineralization, and hot springs. Furthermore on the field, they will be able to do a link between the external and internal geodynamics processes usually studied separately in middle school. The poster presented will detail the first field trip in Taiwan realized in May 2013 by the LFS 4th grade students and will be made by the students going in June 2014. Thus, this activity will allow them to get a perspective of the topic that they will discover on the field trip.

  17. Chemical and Physical Weathering in a Hot-arid, Tectonically Active Alluvial System (Anza-Borrego Desert, CA)

    NASA Astrophysics Data System (ADS)

    Joo, Y. J.; Elwood Madden, M.; Soreghan, G. S.

    2014-12-01

    Climate and tectonics are primary controls on bedrock erosion, and sediment production, transport, and deposition. Additionally, silicate weathering in tectonically active regions is known to play a significant role in global climate owing to the high rates of physical erosion and exposure of unweathered bedrock to chemical weathering, which removes CO2 from the atmosphere. Therefore, the feedback between weathering and climate is key to understanding climate change through Earth history. This study investigates chemical and physical weathering of alluvial sediments in the Anza-Borrego Desert, California, located in the southern part of the San Andreas Fault System. This setting provides an ideal opportunity to study weathering in a hot and arid climate with mean annual temperatures of ~23 °C and mean annual precipitation of ~160 mm in the basin. Samples were collected along a proximal-to-distal transect of an alluvial-fan system sourced exclusively from Cretaceous tonalite of the Peninsular Range. The single bedrock lithology enables exploration of the effects of other variables — climate, transport distance, drainage area, and tectonics— on the physical and chemical properties of the sediments. Although minimal overall (CIA = 56-61), the degree of chemical weathering increases down transect, dominated by plagioclase dissolution. BET surface area of the mud (<63µm) fraction decreases distally, which is consistent with coarsening grain-size. Chemical alteration and BET surface area both increase in a distal region, within the active Elsinore Fault zone. Extensive fracturing here, together with a more-humid Pleistocene climate likely facilitated in-situ bedrock weathering; specifically, dissolution of primary minerals (e.g. plagioclase), preceding the arid alluvial erosion, transport, and deposition in the Holocene. This study further seeks to disentangle the complex record of the climate and tectonic signals imprinted in these sediments.

  18. Change in biochemical and morphological characteristics of Lonicera caerulea in tectonically active zone of the Dzhazator River Valley (Altai Mountains)

    NASA Astrophysics Data System (ADS)

    Boyarskikh, I. G.; Khudyaev, S. A.; Platonova, S. G.; Kolotukhin, S. P.; Shitov, A. V.; Kukushkina, T. A.; Chankina, O. V.

    2012-12-01

    Local geophysical and geochemical anomalies affect the polymorphism of taste variations, berry shape, and content of some biologically active substances in Lonicera caerulea leaves in the tectonically active Altai Mountains (Dzhazator River basin).

  19. Tectonic activity evolution of the Scotia-Antarctic Plate boundary from mass transport deposit analysis

    NASA Astrophysics Data System (ADS)

    Pérez, Lara F.; Bohoyo, Fernando; Hernández-Molina, F. Javier; Casas, David; Galindo-Zaldívar, Jesús; Ruano, Patricia; Maldonado, Andrés.

    2016-04-01

    The spatial distribution and temporal occurrence of mass transport deposits (MTDs) in the sedimentary infill of basins and submerged banks near the Scotia-Antarctic plate boundary allowed us to decode the evolution of the tectonic activity of the relevant structures in the region from the Oligocene to present day. The 1020 MTDs identified in the available data set of multichannel seismic reflection profiles in the region are subdivided according to the geographic and chronological distributions of these features. Their spatial distribution reveals a preferential location along the eastern margins of the eastern basins. This reflects local deformation due to the evolution of the Scotia-Antarctic transcurrent plate boundary and the impact of oceanic spreading along the East Scotia Ridge (ESR). The vertical distribution of the MTDs in the sedimentary record evidences intensified regional tectonic deformation from the middle Miocene to Quaternary. Intensified deformation started at about 15 Ma, when the ESR progressively replaces the West Scotia Ridge (WSR) as the main oceanic spreading center in the Scotia Sea. Coevally with the WSR demise at about 6.5 Ma, increased spreading rates of the ESR and numerous MTDs were formed. The high frequency of MTDs during the Pliocene, mainly along the western basins, is also related to greater tectonic activity due to uplift of the Shackleton Fracture Zone by tectonic inversion and extinction of the Antarctic-Phoenix Ridge and involved changes at late Pliocene. The presence of MTDs in the southern Scotia Sea basins is a relevant indicator of the interplay between sedimentary instability and regional tectonics.

  20. Relative earthquake location for remote offshore and tectonically active continental regions using surface waves

    NASA Astrophysics Data System (ADS)

    Cleveland, M.; Ammon, C. J.; Vandemark, T. F.

    2015-12-01

    Earthquake locations are a fundamental parameter necessary for reliable seismic monitoring and seismic event characterization. Within dense continental seismic networks, event locations can be accurately and precisely estimated. However, for many regions of interest, existing catalog data and traditional location methods provide neither accurate nor precise hypocenters. In particular, for isolated continental and offshore areas, seismic event locations are estimated primarily using distant observations, often resulting in inaccurate and imprecise locations. The use of larger, moderate-size events is critical to the construction of useful travel-time corrections in regions of strong geologic heterogeneity. Double difference methods applied to cross-correlation measured Rayleigh and Love wave time shifts are an effective tool at providing improved epicentroid locations and relative origin-time shifts in these regions. Previous studies have applied correlation of R1 and G1 waveforms to moderate-magnitude vertical strike-slip transform-fault and normal faulting earthquakes from nearby ridges. In this study, we explore the utility of phase-match filtering techniques applied to surface waves to improve cross-correlation measurements, particularly for smaller magnitude seismic events. We also investigate the challenges associated with applying surface-wave location methods to shallow earthquakes in tectonically active continental regions.

  1. Seismic hazard assessment of Syria using seismicity, DEM, slope, active tectonic and GIS

    NASA Astrophysics Data System (ADS)

    Ahmad, Raed; Adris, Ahmad; Singh, Ramesh

    2016-07-01

    In the present work, we discuss the use of an integrated remote sensing and Geographical Information System (GIS) techniques for evaluation of seismic hazard areas in Syria. The present study is the first time effort to create seismic hazard map with the help of GIS. In the proposed approach, we have used Aster satellite data, digital elevation data (30 m resolution), earthquake data, and active tectonic maps. Many important factors for evaluation of seismic hazard were identified and corresponding thematic data layers (past earthquake epicenters, active faults, digital elevation model, and slope) were generated. A numerical rating scheme has been developed for spatial data analysis using GIS to identify ranking of parameters to be included in the evaluation of seismic hazard. The resulting earthquake potential map delineates the area into different relative susceptibility classes: high, moderate, low and very low. The potential earthquake map was validated by correlating the obtained different classes with the local probability that produced using conventional analysis of observed earthquakes. Using earthquake data of Syria and the peak ground acceleration (PGA) data is introduced to the model to develop final seismic hazard map based on Gutenberg-Richter (a and b values) parameters and using the concepts of local probability and recurrence time. The application of the proposed technique in Syrian region indicates that this method provides good estimate of seismic hazard map compared to those developed from traditional techniques (Deterministic (DSHA) and probabilistic seismic hazard (PSHA). For the first time we have used numerous parameters using remote sensing and GIS in preparation of seismic hazard map which is found to be very realistic.

  2. Explosively activated egress area

    NASA Technical Reports Server (NTRS)

    Bement, L. J.; Bailey, J. W. (Inventor)

    1983-01-01

    A lightweight, add on structure which employs linear shaped pyrotechnic charges to smoothly cut an airframe along an egress area periphery is provided. It compromises reaction surfaces attached to the exterior surface of the airframe's skin and is designed to restrict the skin deflection. That portion of the airframe within the egress area periphery is jettisoned. Retention surfaces and sealing walls are attached to the interior surface of the airframe's skin and are designed to shield the interior of the aircraft during detonation of the pyrotechnic charges.

  3. Quaternary tectonic and sedimentary history of the shelf area between the Saros and Edremit Troughs, NE Aegean Turkey

    NASA Astrophysics Data System (ADS)

    Alpar, B.

    2009-04-01

    On the basis of new swath bathymetric and high-resolution sparker reflection data, Quaternary tectonic and sedimentary history of the Aegean continental shelf area between the gulfs of Saros and Edremit was investigated. These gulfs accommodate two complex neotectonic structures which control the major geodynamic processes in the region; these are the northern and middle strands of the North Anatolian fault (NAF), respectively. A mature erosion surface, partially intersected by some vertical faults, can indeed be interpreted from the clear reflections over the Miocene basement, which is represented by various folded layers. This acoustical surface forms the base level of deposition for the studied shelf area and overlain by various depositional basins elongated between the gulfs of Saros and Edremit. Depending on the global sea level changes, water exchange between the seas of Mediterranean and Marmara, and partly on some terrestrial inputs, these basins have been developed. Sea-level decreased during the glacial stages while the Mediterranean conditions prevailed during the interglacial stages. As evidenced from the formation of the Pleistocene coastal terraces in the Canakkale (Dardanelles) Strait region and under the control of compressional forces along the NAF zone a regional uplift of 0.2-0.9 mm per year is another major component in the tectonic history. The depositional units over the mature Pliocene erosion surface were mainly controlled by the fluvial discharges of the Karamenderes paleo-river and some others during the postglacial times, by sea-level oscillations which determined the proximity of basins to river mouths, and by oceanographic conditions. A rise in basement has been traced at 60-65 m below the modern sea level which has been played an important role in the sediment transportation occurred at the exit of the Canakkale Strait. The folded layers above the acoustical basement coincide with the development of the transpressional Anafartalar

  4. Tectonically-beheaded drainages (wind gaps), Palmdale area, Los Angeles, County, California

    SciTech Connect

    Lachapelle, W.A. ); Shlemon, R.J.

    1993-04-01

    Five discrete wind gaps, informally designated 1 (west) through 5 (east), occur along a 6.5 km distance between the Anaverde water gap on the west and the Old Harold Road drainage on the east at Palmdale, California. Aerial photographic and geomorphic interpretations combined with boring and trench logs indicate that the windgaps were once courses of low-order, northward-flowing drainages now beheaded by the San Andreas Fault (SAF). Wind gaps 2 through 5 now contain only intermittent underfit streams, but are bordered by remnants of high-level fluvial terrace gravels attesting to long periods of flow across the SAF before cutoff by tectonic displacement. Representative wind gap 5 contains approximately 6-m of fining-upward sands and silts, and yields an approximately 10,000-yr radiocarbon date from near the base of the section. Based mainly on wind gap morphology and on an average right-lateral slip rate of about 35 mm/yr for this segment of the SAF, the authors suggest three possible hypotheses to account for the origin of the Palmdale area wind gaps: (1) they were beheaded by continual lateral movement of the SAF; (2) they maintained flow across the SAF during much of Pleistocene time, but were eventually defeated by an increasing rate of slip in latest Pleistocene time or (3) they continued flow across the SAF until latest Pleistocene time, particularly during pluvial epochs, but were eventually cut off owing to the onset of more aridic climatic and sedimentation regimes in early Holocene time.

  5. Linking Europa's plume activity to tides, tectonics, and liquid water

    NASA Astrophysics Data System (ADS)

    Rhoden, Alyssa Rose; Hurford, Terry A.; Roth, Lorenz; Retherford, Kurt

    2015-06-01

    Much of the geologic activity preserved on Europa's icy surface has been attributed to tidal deformation, mainly due to Europa's eccentric orbit. Although the surface is geologically young (30-80 Myr), there is little information as to whether tidally-driven surface processes are ongoing. However, a recent detection of water vapor near Europa's south pole suggests that it may be geologically active. Initial observations indicated that Europa's plume eruptions are time-variable and may be linked to its tidal cycle. Saturn's moon, Enceladus, which shares many similar traits with Europa, displays tidally-modulated plume eruptions, which bolstered this interpretation. However, additional observations of Europa at the same time in its orbit failed to yield a plume detection, casting doubt on the tidal control hypothesis. The purpose of this study is to analyze the timing of plume eruptions within the context of Europa's tidal cycle to determine whether such a link exists and examine the inferred similarities and differences between plume activity on Europa and Enceladus. To do this, we determine the locations and orientations of hypothetical tidally-driven fractures that best match the temporal variability of the plumes observed at Europa. Specifically, we identify model faults that are in tension at the time in Europa's orbit when a plume was detected and in compression at times when the plume was not detected. We find that tidal stress driven solely by eccentricity is incompatible with the observations unless additional mechanisms are controlling the eruption timing or restricting the longevity of the plumes. The addition of obliquity tides, and corresponding precession of the spin pole, can generate a number of model faults that are consistent with the pattern of plume detections. The locations and orientations of these hypothetical source fractures are robust across a broad range of precession rates and spin pole directions. Analysis of the stress variations across

  6. GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany).

    PubMed

    Berberich, Gabriele; Schreiber, Ulrich

    2013-01-01

    In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO₂, Helium, Radon and H₂S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

  7. Quarternary tectonics, Task 1

    SciTech Connect

    Bell, J.W.

    1993-09-30

    Activities conducted for the evaluation of the geology and seismotectonics stability of Yucca Mountain as a potential site for the underground disposal of high-level radioactive wastes continued. Tasks concerned with quaternary tectonics include: scheduling of photography of Little Skull Mountain area; the collection and dating of rock varnish samples from the 1932 Cedar Mountain earthquake area for carbon 14 AMS and cation-ratio analysis; collection of samples for thermoluminescence dating from the 1932 Cedar Mountain earthquake area; mapping of the northern area of Crater Flat; and surveying of the May 17, 1993 Eureka the Valley earthquake area.

  8. Geological and InSAR surveys highlight tectonic hazard in densely inhabited areas on the lower southeastern flank of Mount Etna volcano, Italy

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Sansosti, Eugenio; Casu, Francesco; Leonardi, Anna; Pepe, Antonio; Pepe, Susi; Solaro, Giuseppe

    2015-04-01

    A constant seaward sliding mechanism is affecting the eastern to southern flanks of Mt. Etna volcano, involving an overall on-shore area of >700 km2.The margins of this unstable area are marked by the Pernicana Fault System to the north and the Ragalna Fault System to the south-west. The unstable area is divided into several blocks characterized by different kinematics and delimited by active faults crossing, in several cases, urban areas, towns and villages. One of these structural discontinuities is the Trecastagni-S.G.La Punta-Aci Trezza fault system, a tectonic structure extending from the volcano summit (where it trends NNW-SSE), to the lower southeastern flank (trending NW-SE) and reaching the coast at the Aci Trezza village (WNW-ESE and E-W). The last segment of this tectonic system crosses several important roads and man-made structures within Aci Trezza, and continues for a few kilometers off-shore crossing the Faraglioni stacks-Lachea island. Recently, analysis of long-period InSAR data has added some details to the sliding motion on the lower south-eastern flank of the volcano, particularly on the S.G.La Punta-Aci Trezza fault segments. Field geological and instrumental data confirmed the slip activity and the extension of the tectonically disturbed areas, highlighting a transition zone between the two main fault segments. On the other hand, some of the features detected by InSAR are not clearly visible in the field and were never detected before by classical geological surveys. These results are of crucial importance in terms of hazard related to tectonic movements, especially in densely inhabited zones such as the south-eastern flank of Etna, where more than half a million people live. The structural details obtained through these kinds of studies may guide future land use planning appropriately also within towns and villages, where aseismic and seismogenic very active faults are evident at the surfaces.

  9. Tectonic triggering of slump sheets in the Upper Cretaceous carbonate succession of the Porto Selvaggio area (Salento peninsula, southern Italy): Synsedimentary tectonics in the Apulian Carbonate Platform

    NASA Astrophysics Data System (ADS)

    Mastrogiacomo, G.; Moretti, M.; Owen, G.; Spalluto, L.

    2012-08-01

    Soft-sediment deformation structures crop out in the Upper Cretaceous carbonate succession in Porto Selvaggio cove in the western Salento peninsula, Apulian foreland, southern Italy. The deformed interval is about 13 m thick and occurs between shallow-water limestones and dolostones formed in peritidal and shallow subtidal environments. It comprises well-bedded grey mudstones interlayered with dark grey laminated microbioclastic wackestones characterized by couplets of closely spaced dark and bright laminae marked by the parallel orientation of calcareous microbioclasts and thin-shelled bivalves. The low biological diversity, scarcity of burrowing biota, and presence of a well preserved fish fauna provide evidence of anoxic conditions occurring in morphological depressions within the platform, and a stagnant, stratified water body affected by weak bottom currents, indicating the sudden development of a localised and short-lived intraplatform basin. Two soft-sediment deformation horizons (slump sheets) separated by undeformed limestones with similar facies occur in this part of the succession. The lower, thicker slump sheet (1.0-1.3 m thick) contains asymmetric and box folds. Well-developed décollement surfaces (locally containing thick brecciated zones) cut the folds, forming small-scale thrust-sheets and indicating mixed plastic to brittle behaviour. The upper, thinner slump sheet (0.25-0.35 m thick) contains only asymmetric folds, indicating plastic behaviour only. The differences in deformation style are attributed to differences in facies. Measurements of fold-axis orientations in the slump sheets show that they moved in similar directions, recording the development of a local, gently dipping palaeoslope. Autogenic (internal) trigger mechanisms are ruled out by a detailed consideration of facies. The slump sheets were triggered by allogenic, tectonic effects, either the weakening of sediment by seismic activity or the tectonically induced steepening of slopes

  10. Thermal evolution of igneous rocks of the Upper Rhine Graben area and their relation to tectonic processes

    NASA Astrophysics Data System (ADS)

    Link, K.; Rahn, M.; Keller, J.

    2003-04-01

    The Upper Rhine Graben (URG) extends over a distance of 300 km from Basel (Switzerland) to Frankfurt (Germany) with an average width of 30--40 km. It is the central segment of the European Cenozoic rift system. The occurrence of Middle Eocene lake deposits is attributed to initial rifting. The main rifting phase started at the end of the Eocene and was followed by prominent uplift in the southern URG area in Miocene time (Schumacher, 2002). The igneous products in the investigated area are mainly primitive, mantle-derived alkaline basaltic rocks, occurring, in most cases, as dikes. The majority of the volcanics are found on the eastern graben shoulder with a concentration in the Freiburg area and the highest frequency in the northern part. No dikes are observed along the main border faults. Previously published K/Ar total rock age data were interpreted as intrusion ages (for review see Keller et al., 2002) and suggest a first activity peak in the Upper Cretaceous, a maximum in Eocene time and a further pronounced peak in the Miocene. This age range doubles the length of the assumed period of graben formation. Apatite fission track dating was applied to selected dikes and nearby country rocks. The temporal relation between volcanic events and the URG shoulder uplift was constrained by comparison of the fission track data of the dikes and country rocks. Important differences in respect to this relation exist among the different rift shoulder segments (Black Forest, Vosges, Palatinate Forest and Odins Forest). References: Keller, J., Kraml, M. &Henjes-Kunst, F. (2002): Schweiz. Mineral. Petrogr. Mitt. 82, 121-130. Schumacher, M.E. (2002): Tectonics, 21: 1-17.

  11. Magnetic fields over active tectonic zones in ocean

    USGS Publications Warehouse

    Kopytenko, Yu. A.; Serebrianaya, P.M.; Nikitina, L.V.; Green, A.W.

    2002-01-01

    The aim of our work is to estimate the electromagnetic effects that can be detected in the submarine zones with hydrothermal activity. It is known that meso-scale flows appear in the regions over underwater volcanoes or hot rocks. Their origin is connected with heat flux and hot jets released from underwater volcanoes or faults in a sea bottom. Values of mean velocities and turbulent velocities in plumes were estimated. Quasiconstant magnetic fields induced by a hot jet and a vortex over a plume top are about 1-40 nT. Variable magnetic fields are about 0.1-1 nT. These magnetic disturbances in the sea medium create an additional natural electromagnetic background that must be considered when making detailed magnetic surveys. ?? 2002 Elsevier Science Ltd. All rights reserved.

  12. Late Quaternary tectonic activity and paleoseismicity of the Eastern Messinia Fault Zone, SW Peloponessus (Messinia, Greece).

    NASA Astrophysics Data System (ADS)

    Valkaniotis, Sotirios; Betzelou, Konstantina; Zygouri, Vassiliki; Koukouvelas, Ioannis; Ganas, Athanassios

    2015-04-01

    The southwestern part of Peloponnesus, Messinia and Laconia, is an area of significant tectonic activity situated near the Hellenic trench. Most of the deformation in this area is accommodated by the Eastern Messinia Fault Zone, bordering the western part of Taygetos Mt range and the west coast of Mani peninsula. The Eastern Messinia Fault Zone (EMFZ) is a complex system of primarily normal faults dipping westwards with a strike of NNW-SSE to N-S direction attaining a total length of more than 100 km from the northern Messinia plain in the north to the southern part of Mani peninsula in the south. The continuity of the EMFZ is disrupted by overlapping faults and relay ramp structures. The central part of the EMFZ, from the town of Oichalia to the city of Kalamata, was investigated by detailed field mapping of fault structures and post-alpine sediment formations together with re-evaluation of historical and modern seismicity. Several fault segments with lengths of 6 to 10 km were mapped, defined and evaluated according to their state of activity and age. Analysis of fault striation measurements along fault planes of the fault zone shows a present regime of WSW-ENE extension, in accordance with focal mechanisms from modern seismicity. Known faults like the Katsareika and Verga faults near the city of Kalamata are interpreted as older-generation faults that are re-activated (e.g. the 1986 Ms 6.0 Kalamata earthquake on Verga Fault) as part of a system of distributed deformation. New fault segments, some of them previously unmapped like the Asprohoma fault to the west of Kalamata, and offshore faults like Kitries and Kourtissa, are being assigned to the EMFZ. Moreover, a paleoseismological trench was excavated in the northern part of Pidima fault segment, one of the most prominent active segments of the central part of the EMFZ, in order to examine the paleoearthquake record of the fault system. A significant number of historical and instrumental earthquakes in the area

  13. Study provides data on active plate tectonics in southeast Asia region

    NASA Astrophysics Data System (ADS)

    Wilson, P.; Rais, J.; Reigber, Ch.; Reinhart, E.; Ambrosius, B. A. C.; Le Pichon, X.; Kasser, M.; Suharto, P.; Majid, Dato'Abdul; Yaakub, Dato'Paduka Awang Haji Othman Bin Haji; Almeda, R.; Boonphakdee, C.

    A major geodynamic study has provided significant new information about the location of active plate boundaries in and around Southeast Asia, as well as deformation processes in the Sulawesi region of Indonesia and tectonic activity in the Philippine archipelago. Results also have confirmed the existence of the so-called Sunda Block, which appears to be rotating with respect to adjacent plates.The study, known as the Geodynamics of South and South-East Asia (GEODYSSEA) project, has been a joint venture of the European Commission and the Association of South- East Asian Nations. It began in 1991 and involved a large team of European and Asian scientists and technicians studying the complex geodynamic processes and natural hazards of the region from the Southeast Asia mainland to the Philippines to northern Australia. Earthquakes, volcanic eruptions, tsunamis, and tectonically induced landslides endanger the lives of millions of people in the region, and the tectonic activity behind these natural hazards results from the convergence and collision of the Eurasian, Philippine, and Indo-Australian Plates at relative velocities of up to 10 cm per year.

  14. Multilayer stress from gravity and its tectonic implications in urban active fault zone: A case study in Shenzhen, South China

    NASA Astrophysics Data System (ADS)

    Xu, Chuang; Wang, Hai-hong; Luo, Zhi-cai; Ning, Jin-sheng; Liu, Hua-liang

    2015-03-01

    It is significant to identify urban active faults for human life and social sustainable development. The ordinary methods to detect active faults, such as geological survey, artificial seismic exploration, and electromagnetic exploration, are not convenient to be carried out in urban area with dense buildings. It is also difficult to supply information about vertical extension of the deeper faults by these methods. Gravity, reflecting the mass distribution of the Earth's interior, provides an alternative way to detect faults, which is more efficient and convenient for urban active fault detection than the aforementioned techniques. Based on the multi-scale decomposition of gravity anomalies, a novel method to invert multilayer horizontal tectonic stresses is proposed. The inverted multilayer stress fields are further used to infer the distribution and stability of the main faults. In order to validate our method, the multilayer stress fields in the Shenzhen fault zone are calculated as a case study. The calculated stress fields show that their distribution is controlled significantly by the strike of the main faults and can be used to derive depths of the faults. The main faults in Shenzhen may range from 4 km to 20 km in the depth. Each layer of the crust is nearly equipressure since the horizontal tectonic stress has small amplitude. It indicates that the main faults in Shenzhen are relatively stable and have no serious impact on planning and construction of the city.

  15. Geomorphic Indicators and Tectonic Implications of the Active Chaochou Fault, Southern Taiwan

    NASA Astrophysics Data System (ADS)

    Hung, J.; Liao, H.

    2003-12-01

    The Chaochou Fault, lying on the easternmost edge of the Pingtung plain, is the major geologic boundary between the Slate Belt to the east and the Western Foothills to the west. According to previous studies, the Chaochou fault is a high-angle reverse fault dipping 75-80 degrees to the east. Along strike, several transverse rivers cut across the fault and form alluvial fans in the foothills, which provide unique morphotectonic features to study the activity of the Chaochou Fault. Digitized data from topographic maps of 1/5,000 to 1/25,000 scales and digital elevation data of 40m resolution were input into GIS software and analyzed to quantitatively evaluate geomorphic indicators such as hypsometric integral, stream length-gradient index and drainage basin asymmetry etc. Anomalies of these indices are further checked in the field on bedrocks, man-made structures and fold and faults, to clarify spatial variations of indicators. These, coupled with GPS data, field survey in the slate belt and uplifted terraces and subsurface seismic profiles, can further constrain spatial and temporal kinematics of the Chaochou fault and the relationship between topographic evolution and subsurface structures. Our preliminary results show that river landforms are highly related to the Chaochou Fault. Drainages were tilted to the west in response to uplifting in the east of the Chaochou Fault. Geomorphic indices indicate that the uplift rate is higher in the north and decreases progressively toward the south. The peak tectonic activity occurs in the area between the Chaochou and the Chishan Fault.

  16. New Insights into the Active Tectonics of Eastern Indonesia from GPS Measurements

    NASA Astrophysics Data System (ADS)

    Susilo, S.; Koulali Idrissi, A.; McClusky, S.; Meilano, I.; Cummins, P. R.; Tregoning, P.; Syafii, A.

    2014-12-01

    The Indonesian archipelago encompasses a wide range of tectonic environments, including island arc volcanism, subduction zones, and arc-continent collision. Many of the details of this tectonic activity are still poorly understood, especially where the Australian continent collides with Indonesia, separating the Sunda Arc in west from that at the Banda Arc in the east. While it seems clear that the Australian plate is subducted under both the Sunda and Banda Arcs, it is not clear what happens along the 1000 km -long stretch in between. The question of just where the plate motion is accommodated is of major importance to assessments of earthquake and tsunami hazard in the region. To help resolve these questions the Geospatial Information Agency of Indonesia has collaborated with the Australian National University and the Bandung Institute of Technology in a GPS campaign spanning much of eastern Indonesia, from Lombok in the west to Alor in the east. We have combined these data with those from previous campaigns, resulting in over 27 campaign and 18 continuous GPS sites being used in the analysis. The improvement in site density allowed us to develop of a more complete description of tectonic activity in this region than has been obtained in previous studies. Our preliminary results suggests that there is a relatively simple transition from subduction at the Java Trench off east Java, to a partitioned convergence along both the Timor Trough and the Flores Thrust in the Nusa Tenggara region.

  17. Recent tectonic activity on Mercury revealed by small thrust fault scarps

    NASA Astrophysics Data System (ADS)

    Watters, Thomas R.; Daud, Katie; Banks, Maria E.; Selvans, Michelle M.; Chapman, Clark R.; Ernst, Carolyn M.

    2016-10-01

    Large tectonic landforms on the surface of Mercury, consistent with significant contraction of the planet, were revealed by the flybys of Mariner 10 in the mid-1970s. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission confirmed that the planet's past 4 billion years of tectonic history have been dominated by contraction expressed by lobate fault scarps that are hundreds of kilometres long. Here we report the discovery of small thrust fault scarps in images from the low-altitude campaign at the end of the MESSENGER mission that are orders of magnitude smaller than the large-scale lobate scarps. These small scarps have tens of metres of relief, are only kilometres in length and are comparable in scale to small young scarps on the Moon. Their small-scale, pristine appearance, crosscutting of impact craters and association with small graben all indicate an age of less than 50 Myr. We propose that these scarps are the smallest members of a continuum in scale of thrust fault scarps on Mercury. The young age of the small scarps, along with evidence for recent activity on large-scale scarps, suggests that Mercury is tectonically active today and implies a prolonged slow cooling of the planet's interior.

  18. Late Paleozoic tectonics of the Solonker Zone in the Wuliji area, Inner Mongolia, China: Insights from stratigraphic sequence, chronology, and sandstone geochemistry

    NASA Astrophysics Data System (ADS)

    Shi, Guanzhong; Song, Guangzeng; Wang, Hua; Huang, Chuanyan; Zhang, Lidong; Tang, Jianrong

    2016-09-01

    The geology in the Wuliji area (including the Enger Us and Quagan Qulu areas) is important for understanding the Late Paleozoic tectonics of the Solonker Zone. Ultramafic/mafic rocks in the Enger Us area, previously interpreted as an ophiolitic suture, are actually lava flows and sills in a Permian turbiditic sequence and a small body of fault breccia containing serpentinite. Subduction zone features, such as accretionary complexes, magmatic arc volcanics or LP/HP metamorphism are absent. Early Permian N-MORB mafic rocks and Late Permian radiolarian cherts accompanied by turbidites and tuffeous rocks indicate a deep water setting. In the Quagan Qulu area, outcrops of the Late Carboniferous to Permian Amushan Formation are composed of volcano-sedimenary rocks and guyot-like reef limestone along with a Late Permian volcano-sedimentary unit. A dacite lava in the Late Permian volcano-sedimentary unit yields a zircon U-Pb age of 254 Ma. The gabbros in the Quagan Qulu area are intruded into the Amushan Formation and caused contact metamorphism of country rocks. Sandstones in the Upper Member of the Amushan Formation contain detrital clasts of volcanic fragments and mineral clasts of crystalline basement rocks (i.e. biotite, muscovite and garnet). Geochemical analysis of volcaniclastic sandstones shows a magmatic affinity to both continental island arc (CIA) and active continental margin (ACM) tectonic settings. A Late Permian incipient rift setting is suggested by analyzing the lithostratigraphic sequence and related magmatism in the Wuliji area. The volcano-sedimentary rocks in the Wuliji area experienced a nearly N-S shortening that was probably related to the Early Mesozoic nearly N-S compression well developed in other areas close to the Wuliji area.

  19. Morphotectonic evolution of triangular facets and wine-glass valleys in the Noakoh anticline, Zagros, Iran: Implications for active tectonics

    NASA Astrophysics Data System (ADS)

    Bahrami, Shahram

    2012-07-01

    The Noakoh anticline is located in Kermanshah province and is part of the Simply Folded Belt of Zagros. Boundaries of 97 triangular facets and 67 wine-glass (W-G) valleys, which formed on anticline limbs, were delineated using Quickbird satellite imagery. The strata dip (D), area (A), base length (BL), topographic slope (S) of facets, the maximum width (M), outlet width (O) and ratio of maximum width to outlet width (W index) of W-G valleys were analysed in detail. Noakoh anticline was subdivided into 9 tectonic zones on the basis of dip, topographic slopes and width of limbs. Results show that there are strong positive correlations between means of D-BL and S-BL pairs. Poor positive correlations exist between means of D-A and S-A pairs. Among W-G valley metrics, the W index has strong relations with D and S parameters. Based on the results, steep facets with long bases and well developed W-G valleys with narrow outlets and wide upper parts are associated with more rotated limbs having steep slopes. Facets on the northeastern slope have more forest cover, micro-organism activity, karstic features and soil cover, whereas facets on relatively drier southwestern slope are characterized by physical weathering processes and minor karstic landforms. This study demonstrates that, apart from tectonic activity as a major control on the morphometry of facets and valleys, climate and slope aspect have also acted as secondary factors on the development of the studied landforms.

  20. A brittle tectonic history of the Internal Dinarides: an inference based on the paleostress study in the Valjevo area (western Serbia)

    NASA Astrophysics Data System (ADS)

    Mladenović, Ana; Trivić, Branislav; Cvetković, Vladica; Pavlović, Radmila

    2014-05-01

    The Internal Dinarides is part of a complex suture zone situated in the central Balkan Peninsula, which present-day tectonic pattern is a result of Late Cretaceous subduction followed by Cenozoic post-collisional and neotectonic phases. Since the Late Miocene, the most important factor controlling regional tectonic processes in this area has been the counterclockwise rotation and northward motion of the Adria plate in respect to the Dinaric orogen. In Serbia, this tectonic process is manifested through constant moderate seismic activity, where stronger earthquakes are recorded mostly along well-known fault systems active in the neotectonic period. However, brittle fault kinematics in this part of the Internal Dinarides is poorly documented. In this research we performed a calculation of the tectonic stress tensors in order to determine brittle tectonic regimes acting in western Serbia (Valjevo mountains range), as well as their relative chronology. Fault-slip data have been collected in geological units of different age and lithology: Permian, Triassic and Cretaceous limestones and Jurassic peridotites and serpentinites. Slip was determined using linear indicators like "carrot shaped" markings, gouging grain grooves and calcite and magnesite fibres. Relative brittle history was determined using criteria of cross-cutting relationships, fracture mineralization and structural features of the brittle overprint of rocks. We distinguished four brittle deformation phases. Phase D1 is characterized by N-S compression, which is indicated by thrust faulting of NE- and NW-trending faults. Phases D2 and D3, are both extensional. However, since we had clear indicators that phase D3 overprints all the previous deformation phases, we suppose that the two extensional phases occurred separately, rather than acting as a single radial extension phase. Deformation phase D2 is characterized by N-S to NE-SW extension, while D3 phase is represented by NW-SE (orogen parallel) extension

  1. New evidence for active tectonics at the boundary of the Kashi Depression, China, from time series InSAR observations

    NASA Astrophysics Data System (ADS)

    He, Ping; Wen, Yangmao; Xu, Caijun; Liu, Yang; Fok, H. S.

    2015-06-01

    Kashi Depression is one of the most complex active tectonic areas in the southern flank of Tianshan, China. Due to the lack of ground observations, the boundary of basin mountain transition zone and the interseismic activity of the Tianshan have not been clearly determined. In this study, 48 Envisat Advanced Synthetic Aperture Radar (ASAR) imagery acquired from 2003 to 2010 are used to construct interferograms for measuring high-resolution interseismic deformation in the Kashi Depression area. A global atmospheric model ERA-Interim provided by the European Center for Medium Range Weather Forecast (ECMWF) and a global network orbital correction are applied to remove atmospheric effect, and the long-wavelength orbital errors, respectively, for the interferograms. Interferometric SAR time series with Atmospheric Estimation Model (InSAR TS + AEM) are then used to obtain a deformation rate map for the Kashi Depression area. The InSAR rate map indicates that the north part of South Atushi Fault has ~ 3 mm/year uplift relative to that of the south part. This result manifests the main tectonic deformation potentially occurs along the Southern Atushi Fault. Based on a simple edge dislocation model, the dip angle of 31 ± 0.6°, slip rate of 2.3 ± 0.1 mm/year, and locking depth of 10.6 ± 0.4 km for the Southern Atushi Fault between Tianshan Orogenic Belt and the Kashi Depression are obtained. This modeling result shows in good agreement with the InSAR derived rates. Our results show that the Southern Atushi Fault is the main active fault in block boundary region between the south of Tianshan and the Tarim Basin.

  2. Late cretaceous extensional tectonics and associated igneous activity on the northern margin of the Gulf of Mexico Basin

    NASA Technical Reports Server (NTRS)

    Bowen, R. L.; Sundeen, D. A.

    1985-01-01

    Major, dominantly compressional, orogenic episodes (Taconic, Acadian, Alleghenian) affected eastern North America during the Paleozoic. During the Mesozoic, in contrast, this same region was principally affected by epeirogenic and extensional tectonism; one episode of comparatively more intense tectonic activity involving extensive faulting, uplift, sedimentation, intrusion and effusion produced the Newark Series of eposits and fault block phenomena. This event, termed the Palisades Disturbance, took place during the Late Triassic - Earliest Jurassic. The authors document a comparable extensional tectonic-igneous event occurring during the Late Cretaceous (Early Gulfian; Cenomanian-Santonian) along the southern margin of the cratonic platform from Arkansas to Georgia.

  3. Seismic body wave separation in volcano-tectonic activity inferred by the Convolutive Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Capuano, Paolo; De Lauro, Enza; De Martino, Salvatore; Falanga, Mariarosaria; Petrosino, Simona

    2015-04-01

    One of the main challenge in volcano-seismological literature is to locate and characterize the source of volcano/tectonic seismic activity. This passes through the identification at least of the onset of the main phases, i.e. the body waves. Many efforts have been made to solve the problem of a clear separation of P and S phases both from a theoretical point of view and developing numerical algorithms suitable for specific cases (see, e.g., Küperkoch et al., 2012). Recently, a robust automatic procedure has been implemented for extracting the prominent seismic waveforms from continuously recorded signals and thus allowing for picking the main phases. The intuitive notion of maximum non-gaussianity is achieved adopting techniques which involve higher-order statistics in frequency domain., i.e, the Convolutive Independent Component Analysis (CICA). This technique is successful in the case of the blind source separation of convolutive mixtures. In seismological framework, indeed, seismic signals are thought as the convolution of a source function with path, site and the instrument response. In addition, time-delayed versions of the same source exist, due to multipath propagation typically caused by reverberations from some obstacle. In this work, we focus on the Volcano Tectonic (VT) activity at Campi Flegrei Caldera (Italy) during the 2006 ground uplift (Ciaramella et al., 2011). The activity was characterized approximately by 300 low-magnitude VT earthquakes (Md < 2; for the definition of duration magnitude, see Petrosino et al. 2008). Most of them were concentrated in distinct seismic sequences with hypocenters mainly clustered beneath the Solfatara-Accademia area, at depths ranging between 1 and 4 km b.s.l.. The obtained results show the clear separation of P and S phases: the technique not only allows the identification of the S-P time delay giving the timing of both phases but also provides the independent waveforms of the P and S phases. This is an enormous

  4. Using vertical electrical soundings for characterizing hydrogeological and tectonic settings in Deir El-Adas area, Yarmouk Basin, Syria

    NASA Astrophysics Data System (ADS)

    Al-Fares, Walid

    2016-06-01

    The present study is aimed at characterizing the subsurface geological and tectonic structure in Deir El-Adas area, by using Vertical Electrical Sounding survey (VES) and hydrogeological investigations, in order to determine the causes of the failure for the majority of the wells drilled in the area. The survey data was treated in three different approaches including direct VES inversion, pseudo-2D method and horizontal profiling, in order to maximize the reliability of the data interpretation. The results revealed the presence of a local faulted anticline structure at the top of the Paleogene formation, underneath the basaltic outcrops where Deir El-Adas village is situated. The appearance of this subsurface anticline structure has complicated the local hydrogeological situation, and most likely led to limitation of the groundwater recharge in the area. Moreover, the performed piezometric and discharge maps indicated the presence of a notable groundwater watershed, in addition to feeble water productivity of the wells drilled adjacent to Deir El-Adas, mostly related to the subsurface geological and tectonic settings in the area.

  5. Active faulting and tectonics of the Ningxia-Hui Autonomous Region, China

    NASA Astrophysics Data System (ADS)

    Qidong, Deng; Sung, Fengmin; Zhu, Shilong; Li, Mengluan; Wang, Tielin; Zhang, Weiqi; Burchfiel, B. C.; Molnar, Peter; Zhang, Peizhen

    1984-06-01

    Strike-slip, thrust, and normal faulting all seem to play an active role in the tectonics of Ningxia. In the southernmost part of the region a major left-lateral strike-slip fault enters the region from the neighboring Gansu province to the west and trends about S65°E. This fault is very clear on Landsat imagery and on aerial photos, and the portion in eastern Gansu and Ningxia broke in the Haiyuan earthquake of December 16, 1920. Displacements of 5-10 m caused by that earthquake are clear in numerous localities and accord with a revised value of the seismic moment of 1.2×1021N m. The eastern end of the Haiyuan fault terminates in a narrow south trending fold and thrust zone. Several other similar, north to northwest trending fold and thrust belts are present in the area about 50-200 km northeast of the Haiyuan fault and divide it into small, apparently relatively undeformed blocks 10-40 km in dimensions. The geometry of the structures in the fold and thrust zones and the apparently shallow depths at the time of deformation suggest that current deformation is similar to that that occurred in the fold and thrust belt of the Idaho-Wyoming Rocky Mountains. North of this area, both the Helan Shan (a horst) and the Yinchuan graben are bounded by clear, active northerly trending normal faults, in some cases with right-lateral strike-slip components. The overall deformation, hence, seems to include dominant components of east-west left-lateral strike-slip movement, northeast-southwest crustal shortening, and northwest-southeast extension. We interpret the extension as a response to a northeast directed force applied to the Ordos block and both this northeast directed force and the left-lateral slip on the Haiyuan fault to the eastward displacement of material on the northeast edge of the Tibetan plateau with respect to Eurasia north of it.

  6. Paleoseismic and geomorphologic evidence of recent tectonic activity of the Pozohondo Fault (Betic Cordillera, SE Spain)

    USGS Publications Warehouse

    Rodríguez-Pascua, M.A.; Pérez-López, R.; Garduño-Monroy, V.H.; Giner-Robles, J.L.; Silva, P.G.; Perucha-Atienza, M.A.; Hernández-Madrigal, V.M.; Bischoff, J.

    2012-01-01

    Instrumental and historical seismicity in the Albacete province (External Prebetic Zone) has been scarcely recorded. However, major strike-slip faults showing NW-SE trending provide geomorphologic and paleoseismic evidence of recent tectonic activity (Late Pleistocene to Present). Moreover, these faults are consistently well oriented under the present stress tensor and therefore, they can trigger earthquakes of magnitude greater than M6, according to the lengths of surface ruptures and active segments recognized in fieldwork. Present landscape nearby the village of Hellin (SE of Albacete) is determined by the recent activity of the Pozohondo Fault (FPH), a NW-SE right-lateral fault with 90 km in length. In this study, we have calculated the Late Quaternary tectonic sliprate of the FPH from geomorphological, sedimentological, archaeoseimological, and paleoseismological approaches. All of these data suggest that the FPH runs with a minimum slip-rate of 0.1 mm/yr during the last 100 kyrs (Upper Pleistocene-Holocene). In addition, we have recognized the last two major paleoearthquakes associated to this fault. Magnitudes of these paleoearthquakes were gretarer than M6 and their recurrence intervals ranged from 6600 to 8600 yrs for the seismic cycle of FPH. The last earthquake was dated between the 1st and 6th centuries, though two earthquakes could be interpreted in this wide time interval, one at the FPH and other from a far field source. Results obtained here, suggest an increasing of the tectonic activity of the Pozohondo Fault during the last 10,000 yrs.

  7. Deformation across the seismic cycle in tectonically active regions: Imaging, modeling, and interpretations

    NASA Astrophysics Data System (ADS)

    Barnhart, William Douglas

    Images of surface displacements in response to tectonic forces can provide independent, spatially dense observations that assist in understanding sub-surface processes. When considered independently or augmented with more traditional observations of active tectonics such as seismicity and ground mapping, these measurements provide constraints on spatially and temporally variable fault behavior across the seismic cycle. Models of fault behavior inferred from these observations in turn allow us to address topics in geologic hazards assessment, the long- and short-term character of strain in deforming regions, and the interactions between faults throughout the crust. In this dissertation, I use remotely sensed observations of ground displacements from interferometric synthetic aperture radar (InSAR) to approach several problems related to earthquake and aseismic fault slip. I establish image processing and inverse methods for better detailing subsurface fault slip and apply these to the 2010-2011 Canterbury, New Zealand sequence. Then, I focus on the active tectonics of the Zagros Mountains in southern Iran. There, I show through orogen-wide InSAR time series analysis that active strain is accommodated across the width of the mountain belt. I also use a combination of InSAR, local seismicity, and structural modeling to demonstrate that strain is vertically partitioned within the Zagros fold-and-thrust belt, with earthquakes controlling deformation in the underlying basement while the overlying sedimentary section shortens in transient, earthquake-triggered aseismic slip events. In certain examples, these aseismic slip events directly contribute to the growth of fault-bend folds. I use these inferences to explore a previously noted discrepancy between observed shortening and that which is expected from known earthquakes. I show that the earthquakes and short-term aseismic slip cannot account for this discrepancy, and that additional deformation mechanisms must be

  8. Coastal and submarine instabilities distribution in the tectonically active SW margin of the Corinth Rift (Psathopyrgos, Achaia, Greece)

    NASA Astrophysics Data System (ADS)

    Simou, Eirini; Papanikolaou, Dimitrios; Lykousis, Vasilios; Nomikou, Paraskevi; Vassilakis, Emmanuel

    2014-05-01

    The Corinth Rift, one of the most active rifts in the world as local extension trending NE-SW reaches the amount of 14±2 mm/yr, corresponds to one of the largest zones of seismically active normal faulting. The formation, growth and migration southwards of the prevailing fault systems, which evolve simultaneously with the intense morphogenetic processes, are overprinted in the age, facies and thickness of the Plio-Pleistocene sequences constructing the south margin of the western Gulf of Corinth. The dominant fault blocks, defined by east-west trending, north dipping normal faults, are accompanied by several morphological features and anomalies, noticed in both the terrestrial and the marine environment. Our main aim has been to examine how the tectonic evolution, in combination with the attendant fierce erosional and sedimentary processes, has affected the morphology through geodynamic processes expressed as failures in the wider coastal area. High resolution multibeam bathymetry in combination with the available land surface data have contributed to submarine and subaerial morphological mapping. These have been used as a basis for the detection of all those geomorphic features that indicate instabilities probably triggered, directly or indirectly, by the ongoing active tectonic deformation. The interpretation of the combined datasets shows that the southwestern margin of the Corinth Rift towards Psathopyrgos fault zone is characterized by intense coastal relief and a narrow, almost absent, continental shelf, which passes abruptly to steep submarine slopes. These steep slope values denote the effects of the most recent brittle deformation and are related to coastal and submarine instabilities and failures. High uplift rates and rapid sedimentation, indicative of the regional high-energy terrestrial and submarine environment, are subsequently balanced by the transportation of the seafloor currents, especially where slope gradients decrease, disintegrating the

  9. Geomorphologic, stratigraphic and sedimentologic evidences of tectonic activity in Sone-Ganga alluvial tract in Middle Ganga Plain, India

    NASA Astrophysics Data System (ADS)

    Sahu, Sudarsan; Saha, Dipankar

    2014-08-01

    The basement of the Ganga basin in the Himalayan foreland is criss-crossed by several faults, dividing the basin into several sub-blocks forming horsts, grabens, or half-grabens. Tectonic perturbations along basement faults have affected the fluvial regime and extent of sediment fill in different parts of the basin during Late Quaternary. The East Patna Fault (EPF) and the West Patna Fault (WPF), located in Sone-Ganga alluvial tract in the southern marginal parts of Middle Ganga Plain (MGP), have remained tectonically active. The EPF particularly has acted significantly and influenced in evolving the geomorphological landscape and the stratigraphic architecture of the area. The block bounded by the two faults has earlier been considered as a single entity, constituting a half-graben. The present investigation (by morpho-stratigraphic and sedimentologic means) has revealed the existence of yet another fault within the half-graben, referred to as Bishunpur-Khagaul Fault (BKF). Many of the long profile morphological characters (e.g., knick-zone, low width-depth ratio) of the Sone River at its lower reaches can be ascribed to local structural deformation along BKF. These basement faults in MGP lie parallel to each other in NE-SW direction.

  10. Soil radon measurements as a potential tracer of tectonic and volcanic activity.

    PubMed

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-15

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  11. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    PubMed Central

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-01-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes. PMID:27079264

  12. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  13. Soil radon measurements as a potential tracer of tectonic and volcanic activity.

    PubMed

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-01-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes. PMID:27079264

  14. Mining-related and tectonic seismicity in the East Mountain area Wasatch Plateau, Utah, U.S.A.

    NASA Astrophysics Data System (ADS)

    Williams, Donna J.; Arabasz, Walter J.

    1989-09-01

    As part of a larger multi-institutional seismic monitoring experiment during June August 1984 in the eastern Wasatch Plateau, Utah, data from a subarray of 20 portable seismographs were used to investigate seismicity in the East Mountain area, an area of active underground coal mining and intense microseismicity. Eight stations of the subarray were concentrated on top of East Mountain, about 600 m above mine level, at an average spacing of 2 to 3 km. The primary objective was the accurate resolution of hypocenters and focal mechanisms for seismic events originating at submine levels. Data from high-resolution seismic reflection profiles and drill-hole sonic logs yielded a detailed velocity model. This model features a strong velocity gradient in the uppermost 1 km, which has a significant effect on takeoff angles for first-arriving P-waves from shallow seismic events. Two hundred epicenters located with a precision of ±500 m cluster within an area about 5 km in diameter and show an evident spatial association with four sites of longwall mining during the study period. A special set of foci rigorously tested for focal-depth reliability indicates submine seismicity predominating within 500 m of mine level and extending at least to 1 km, and perhaps to 2 km, below mine level. Continuous monitoring for a 61-day period (June 15 August 15) bracketed a 16-day mining shutdown (July 7 22) during which significant seismicity, comparable to that observed before the shutdown, was observed. Ten focal mechanisms for seismic events originating at or down to 2 km below mine level nearly all imply reverse faulting, consistent with previous results and the inferred tectonic stress field. Enigmatic events recorded with all dilatational first motions can be fit with double-couple normal-faulting solutions if they in fact occur above mine level, perhaps reflecting overburden subsidence. If these events are constrained to occur at mine level, their first-motion distributions are

  15. Relationship between observed upper mantle structures and recent tectonic activity across the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Biryol, C. Berk; Wagner, Lara S.; Fischer, Karen M.; Hawman, Robert B.

    2016-05-01

    The lithospheric structure of the Southeastern United States is a product of earlier episodes of continental collision and breakup. The region is located in the interior of the North American Plate, away from active plate margins. However, there is ongoing tectonism in the region with multiple zones of seismicity, uplifting arches, and Cenozoic intraplate volcanism. The mechanisms controlling this activity and the state of stress remain enigmatic. Two important factors are plate strength and preexisting, inherited structures. Here we present new tomographic images of the upper mantle beneath the Southeastern United States, revealing large-scale structural variations in the upper mantle. Examples include the relatively thick lithospheric mantle of stable North America that abruptly thins beneath the Paleozoic Appalachian orogeny, and the slow upper mantle of the Proterozoic Reelfoot rift. Our results also indicate fast seismic velocity patterns that can be interpreted as ongoing lithospheric foundering. This provides a viable explanation for seismicity, uplifting, and young intraplate volcanism. We postulate that not only tectonic inheritance but also continuing lithospheric foundering may control the ongoing activity of the region long after it became a passive margin. Based on distinct variations in the geometry and thickness of the lithospheric mantle and foundered lithosphere, we propose that piecemeal delamination has occurred beneath the region throughout the Cenozoic, removing a significant amount of reworked/deformed mantle lithosphere. Ongoing lithospheric foundering beneath the eastern margin of stable North America explains significant variations in thickness of lithospheric mantle across the former Grenville deformation front.

  16. Evaluation of the relative tectonic activity in the eastern Lake Van basin, East Turkey

    NASA Astrophysics Data System (ADS)

    Sağlam Selçuk, Azad

    2016-10-01

    The eastern part of the Lake Van basin (Van region, Turkey) is controlled by reverse faults, such as the Gürpınar, Everek and Alaköy faults. These represent the major tectonic structures within the Van region and have caused many devastating earthquakes. Based on quantitative analyses, the Quaternary activity and topographic relief control of each of these faults was investigated. The Gürpınar, Everek and Alaköy faults are restricted to the southern slopes of the Güzelsu, Everek, and Karasu basins, respectively. Analyses of the mountain front sinuosity (Smf) and valley floor width-to-height ratio (Vf) suggest high activity along the Gürpınar fault, the Everek fault, and the western part of the Alaköy fault. Furthermore, based on the integration between Smf and Vf, the estimated uplift rates were observed to increase from north to south. The Gürpınar and Everek hanging-wall blocks are characterized by uplift rates of > 0.5 mm yr- 1, whereas the Alaköy fault exhibited a rate of 0.05 to 0.5 mm yr- 1. These faults produce knickpoints or knickzones, complex basin hypsometric curves, and high values of the stream length-gradient index. Based on these geomorphic analyses, it was established that the tectonic activity of both the Gürpınar and Everek faults is greater than that of the Alaköy fault.

  17. Active tectonics and Quaternary landscape evolution across the western Panama block, Costa Rica, Central America

    NASA Astrophysics Data System (ADS)

    Marshall, Jeffrey Scott

    Three aspects of active tectonism are examined across central Costa Rica: (1) fault kinematics; (2) volcanic arc retreat; and (3) spatially variable coastal uplift. Diffuse faulting along the Central Costa Rica Deformed Belt (CCRDB) defines the western margin of the Panama block and aligns with the rough-smooth boundary (RSB) on the subducting Cocos plate. Sub-horizontal subduction of rough, hotspot thickened crust (Cocos Ridge and seamounts) shifts active shortening into the volcanic arc along the CCRDB. Mesoscale faults express variable kinematics across three domains: transtension in the forearc, transcurrent motion across the volcanic arc, and transpression in the back arc. Fault kinematics agree with seismicity and GPS data, and isotopic ages confirm that faulting postdates the late Neogene onset of shallow subduction. Stratigraphic correlation augmented by 40Ar/39Ar dating constrain the timing of Quaternary arc migration from the Neogene Aguacate range to the modern Cordillera Central. The Valle Central basin, between the cordilleras, filled with thick sequences of lavas, pyroclastic flows, and lahars. Middle Pleistocene drainage capture across the Aguacate arc linked the Valle Central with the Pacific slope and ash flows descended onto the coastal Orotina debris fan. Arc retreat reflects slab shallowing and enhanced tectonic erosion as rough crust entered the subduction zone. Differing subduction parameters across the RSB (crustal age, slab dip, roughness) produce marked contrasts in coastal tectonism. Varying uplift rates across coastal faults reflect sub-horizontal subduction of seamount roughness. Three groups (I--III) of fluvial terraces are correlated along the coast by isotopic ages and geomorphic characteristics. Base level fluctuations and terrace genesis reflect interaction between eustatic sea level and spatially variable rock uplift. Low uplift rates (north of RSB), yield one surface per terrace group, whereas moderate rates (south of RSB

  18. Glacier ice mass fluctuations and fault instability in tectonically active Southern Alaska

    USGS Publications Warehouse

    Sauber, J.M.; Molnia, B.F.

    2004-01-01

    Across the plate boundary zone in south central Alaska, tectonic strain rates are high in a region that includes large glaciers undergoing wastage (glacier retreat and thinning) and surges. For the coastal region between the Bering and Malaspina Glaciers, the average ice mass thickness changes between 1995 and 2000 range from 1 to 5 m/year. These ice changes caused solid Earth displacements in our study region with predicted values of -10 to 50 mm in the vertical and predicted horizontal displacements of 0-10 mm at variable orientations. Relative to stable North America, observed horizontal rates of tectonic deformation range from 10 to 40 mm/year to the north-northwest and the predicted tectonic uplift rates range from approximately 0 mm/year near the Gulf of Alaska coast to 12 mm/year further inland. The ice mass changes between 1995 and 2000 resulted in discernible changes in the Global Positioning System (GPS) measured station positions of one site (ISLE) located adjacent to the Bagley Ice Valley and at one site, DON, located south of the Bering Glacier terminus. In addition to modifying the surface displacements rates, we evaluated the influence ice changes during the Bering glacier surge cycle had on the background seismic rate. We found an increase in the number of earthquakes (ML???2.5) and seismic rate associated with ice thinning and a decrease in the number of earthquakes and seismic rate associated with ice thickening. These results support the hypothesis that ice mass changes can modulate the background seismic rate. During the last century, wastage of the coastal glaciers in the Icy Bay and Malaspina region indicates thinning of hundreds of meters and in areas of major retreat, maximum losses of ice thickness approaching 1 km. Between the 1899 Yakataga and Yakutat earthquakes (Mw=8.1, 8.1) and prior to the 1979 St. Elias earthquake (M s=7.2), the plate interface below Icy Bay was locked and tectonic strain accumulated. We used estimated ice mass

  19. Coseismic landslides reveal near-surface rock strength in a high-relief tectonically active setting

    USGS Publications Warehouse

    Gallen, Sean F; Clark, Marin K; Godt, Jonathan W.

    2014-01-01

    We present quantitative estimates of near-surface rock strength relevant to landscape evolution and landslide hazard assessment for 15 geologic map units of the Longmen Shan, China. Strength estimates are derived from a novel method that inverts earthquake peak ground acceleration models and coseismic landslide inventories to obtain material proper- ties and landslide thickness. Aggregate rock strength is determined by prescribing a friction angle of 30° and solving for effective cohesion. Effective cohesion ranges are from 70 kPa to 107 kPa for 15 geologic map units, and are approximately an order of magnitude less than typical laboratory measurements, probably because laboratory tests on hand-sized specimens do not incorporate the effects of heterogeneity and fracturing that likely control near-surface strength at the hillslope scale. We find that strength among the geologic map units studied varies by less than a factor of two. However, increased weakening of units with proximity to the range front, where precipitation and active fault density are the greatest, suggests that cli- matic and tectonic factors overwhelm lithologic differences in rock strength in this high-relief tectonically active setting.

  20. Stability of active mantle upwelling revealed by net characteristics of plate tectonics.

    PubMed

    Conrad, Clinton P; Steinberger, Bernhard; Torsvik, Trond H

    2013-06-27

    Viscous convection within the mantle is linked to tectonic plate motions and deforms Earth's surface across wide areas. Such close links between surface geology and deep mantle dynamics presumably operated throughout Earth's history, but are difficult to investigate for past times because the history of mantle flow is poorly known. Here we show that the time dependence of global-scale mantle flow can be deduced from the net behaviour of surface plate motions. In particular, we tracked the geographic locations of net convergence and divergence for harmonic degrees 1 and 2 by computing the dipole and quadrupole moments of plate motions from tectonic reconstructions extended back to the early Mesozoic era. For present-day plate motions, we find dipole convergence in eastern Asia and quadrupole divergence in both central Africa and the central Pacific. These orientations are nearly identical to the dipole and quadrupole orientations of underlying mantle flow, which indicates that these 'net characteristics' of plate motions reveal deeper flow patterns. The positions of quadrupole divergence have not moved significantly during the past 250 million years, which suggests long-term stability of mantle upwelling beneath Africa and the Pacific Ocean. These upwelling locations are positioned above two compositionally and seismologically distinct regions of the lowermost mantle, which may organize global mantle flow as they remain stationary over geologic time. PMID:23803848

  1. Stability of active mantle upwelling revealed by net characteristics of plate tectonics.

    PubMed

    Conrad, Clinton P; Steinberger, Bernhard; Torsvik, Trond H

    2013-06-27

    Viscous convection within the mantle is linked to tectonic plate motions and deforms Earth's surface across wide areas. Such close links between surface geology and deep mantle dynamics presumably operated throughout Earth's history, but are difficult to investigate for past times because the history of mantle flow is poorly known. Here we show that the time dependence of global-scale mantle flow can be deduced from the net behaviour of surface plate motions. In particular, we tracked the geographic locations of net convergence and divergence for harmonic degrees 1 and 2 by computing the dipole and quadrupole moments of plate motions from tectonic reconstructions extended back to the early Mesozoic era. For present-day plate motions, we find dipole convergence in eastern Asia and quadrupole divergence in both central Africa and the central Pacific. These orientations are nearly identical to the dipole and quadrupole orientations of underlying mantle flow, which indicates that these 'net characteristics' of plate motions reveal deeper flow patterns. The positions of quadrupole divergence have not moved significantly during the past 250 million years, which suggests long-term stability of mantle upwelling beneath Africa and the Pacific Ocean. These upwelling locations are positioned above two compositionally and seismologically distinct regions of the lowermost mantle, which may organize global mantle flow as they remain stationary over geologic time.

  2. The depositional records of two coastal lakes in south-central Chile (Lago Lanalhue and Lago Lleu Lleu, 38°S): Active forearc tectonics and climate variability

    NASA Astrophysics Data System (ADS)

    Echtler, H. P.; Stefer, S.; Moernaut, J.; Melnick, D.; Arz, H. W.; Lamy, F.; Haug, G. H.

    2008-12-01

    On millennial time scales, the southern Chilean active margin is not only characterized by active tectonics and subduction-related coastal deformation, but also influenced by pronounced variations in the prevailing climate conditions. Here we focus on the depositional records of two coastal lakes in the southern part of the Arauco Peninsula (38°S, Lago Lanalhue and Lago Lleu Lleu), an area very sensitive to changes in both climate and tectonics. For the present study, we used a multi-proxy approach including seismic reflection surveys, sedimentological, mineralogical, and geochemical analyses, supported by radiocarbon dating. Seismic reflection analyses reveal that Lago Lanalhue and Lago Lleu Lleu developed within former river valleys that once drained into the Pacific Ocean. During the early Holocene, the ancient rivers were dammed by rising sills due to inverse faulting and tectonic uplift, turning first into marginal-marine lagoonal systems and subsequently evolving into lakes. On the basis of sedimentological analyses and radiocarbon dating, the different stages of the lakes development have been reconstructed in consideration of the regional tectonic and climatic history. The comparison of the transitions between different stratigraphic units with contemporaneous variations in the global sea level, allowed the calculation of Holocene uplift rates. These are about twenty times higher for the upraised sills than for the lakes themselves. Therefor, we interpret the sills to be the surface expression of a blind thrust associated with a prominent inverse fault (Morguilla Fault) controlling uplift and folding of the Arauco Peninsula. Geochemical data from the lacustrine part of the sedimentary sequences reveal a continuous record of the middle to late Holocene regional climate history. The results indicate more arid conditions during the middle Holocene and more humid conditions during the late Holocene. An additional increase in climate variability is recorded

  3. Tectonic and Structural Controls of Geothermal Activity in the Great Basin Region, Western USA

    NASA Astrophysics Data System (ADS)

    Faulds, J. E.; Hinz, N.; Kreemer, C. W.

    2012-12-01

    We are conducting a thorough inventory of structural settings of geothermal systems (>400 total) in the extensional to transtensional Great Basin region of the western USA. Most of the geothermal systems in this region are not related to upper crustal magmatism and thus regional tectonic and local structural controls are the most critical factors controlling the locations of the geothermal activity. A system of NW-striking dextral faults known as the Walker Lane accommodates ~20% of the North American-Pacific plate motion in the western Great Basin and is intimately linked to N- to NNE-striking normal fault systems throughout the region. Overall, geothermal systems are concentrated in areas with the highest strain rates within or proximal to the eastern and western margins of the Great Basin, with the high temperature systems clustering in transtensional areas of highest strain rate in the northwestern Great Basin. Enhanced extension in the northwestern Great Basin probably results from the northwestward termination of the Walker Lane and the concomitant transfer of dextral shear into west-northwest directed extension, thus producing a broad transtensional region. The capacity of geothermal power plants also correlates with strain rates, with the largest (hundreds of megawatts) along the Walker Lane or San Andreas fault system, where strain rates range from 10-100 nanostrain/yr to 1,000 nanostrain/yr, respectively. Lesser systems (tens of megawatts) reside in the Basin and Range (outside the Walker Lane), where local strain rates are typically < 10 nanostrain/yr. Of the 250+ geothermal fields catalogued, step-overs or relay ramps in normal fault zones serve as the most favorable setting, hosting ~32% of the systems. Such areas have multiple, overlapping fault strands, increased fracture density, and thus enhanced permeability. Other common settings include a) intersections between normal faults and strike-slip or oblique-slip faults (27%), where multiple minor

  4. Variations of fluvial tufa sub-environments in a tectonically active basin, Pleistocene Teruel Basin, NE Spain

    NASA Astrophysics Data System (ADS)

    Camuera, Jon; Alonso-Zarza, Ana M.; Rodríguez-Berriguete, Álvaro; Meléndez, Alfonso

    2015-12-01

    The Pleistocene Tortajada fluvial deposit occurs in the eastern active margin of the Teruel Basin. It developed in the early stages of opening of the basin and at present is disconnected to the Alfambra River. The preserved deposits show that the fluvial system consisted in three different sub-environments including: Upper Terraces, Ponds and Cascades. The main facies are framestones of stems, phytoclastic rudstone, framestone of bryophytes, peloidal and filamentous stromatolites, mudstone and detrital (conglomerates and slope-breccias) facies. These facies are arranged in three different sequence types, all of them showing a lower detrital term followed by pond and, in cases, cascade deposits. The microfacies analyses reveal that both biotic and abiotic processes performed an important role in the deposition within the river. Isotopic analyses (δ18O from - 8.58‰ to - 6.70‰ VPDB and δ13C from - 7.44‰ to - 3.97‰ VPDB) are indicative of meteoric water within a hydrologically open system. The carbonate hinterland rocks, together with a semi-arid to sub-humid climate favored carbonate accumulation within the river. Our results point out that the location, morphology and sedimentary sequences of the Tortajada fluvial system had an important tectonic control. The situation of the main and secondary faults controlled the paleomorphology of the river floor. Thus cascades are found in areas of important step faults, whereas the spaces between faults were occupied by fluviatile/lacustrine areas. In addition the development of the different sedimentary sequences was also a reflection of movements of these faults. In short, our study may confirm that tectonism is an important control on tufa development.

  5. Archaeological evidences of the tectonic activity of Shueib Structure (NW Jordan)

    NASA Astrophysics Data System (ADS)

    Al-Awabdeh, Mohammad; Azañón, J. Miguel; Pérez-Peña, J. Vicente; Booth-Rea, Gillermo

    2014-05-01

    Archaeological damage in buried ruins often offers an excellent record of recent tectonic activity. The lower Jordan valley has experienced a continuous occupation in the last 5000 year, being frequent archaeological remains of human settlements along the valley. In this work we studied the Early Neolithic-to-Middle Islamic Periods archaeological site of Tall al-Hammam (Arabic name, ¨Hill of Baths¨). This ruin is located 27 km southwest of Amman city and it constitutes the largest Bronze Age archaeological site in Jordan. It consists of two main parts; the Upper Tall and the Lower Tall. This ruin lies within the southwestern termination of the Shueib structure (SHS); a Cretaceous fold-bend fault structure thought inactive through the entire Cenozoic. The relics, in the lower Tall, show clear fault-related damage in some walls. Two Middle Bronze Age (MBA) walls are displaced 26 and 20 cm respectively, according with a NNE-SSW fault plane. Apart of wall displacements, hundreds of joints and cracks in boulders of the walls are present. They strike generally NW-SE and NE-SW. Both archaeological evidences, boulder fractures and walls distortion, are coherent with the present-day tectonic setting of the Dead Sea Transform Fault in the region, and suggest a Quaternary reactivation of the SHS.

  6. Tectonic history and thrust-fold deformation style of seismically active structures near Coalinga

    SciTech Connect

    Namson, J.S. ); Davis, T.L.; Lagoe, M.B.

    1990-01-01

    The stratigraphy of the Coalinga region can be divided into tectostratigraphic facies whose boundaries delineate two major tectonic events - one in the mid-Cenozoic (38-17 Ma) and one in the late Cenozoic (less than 3 Ma). The succession of these tectostratigraphic facies, and an integration of geology, subsurface well data, a seismic-reflection profile, and earthquake seismicity on a retrodeformable cross section, yield a model for the tectonic evolution of the Coalinga region. This model suggests that the structural style of both deformational events is characteristic of fold and thrust belts. The model also indicates that the causative fault of the May 2 earthquake is a ramped thrust. The results of this study, in combination with regional geologic relations, suggest that the Coalinga region is part of an active fold and thrust belt which borders the west and south sides of the San Joaquin Valley. The potential for future earthquakes due to movement of other blind thrust faults within this belt should be evaluated.

  7. Simulation of active tectonic processes for a convecting mantle with moving continents

    USGS Publications Warehouse

    Trubitsyn, V.; Kaban, M.; Mooney, W.; Reigber, C.; Schwintzer, P.

    2006-01-01

    Numerical models are presented that simulate several active tectonic processes. These models include a continent that is thermally and mechanically coupled with viscous mantle flow. The assumption of rigid continents allows use of solid body equations to describe the continents' motion and to calculate their velocities. The starting point is a quasi-steady state model of mantle convection with temperature/ pressure-dependent viscosity. After placing a continent on top of the mantle, the convection pattern changes. The mantle flow subsequently passes through several stages, eventually resembling the mantle structure under present-day continents: (a) Extension tectonics and marginal basins form on boundary of a continent approaching to subduction zone, roll back of subduction takes place in front of moving continent; (b) The continent reaches the subduction zone, the extension regime at the continental edge is replaced by strong compression. The roll back of the subduction zone still continues after closure of the marginal basin and the continent moves towards the upwelling. As a result the ocean becomes non-symmetric and (c) The continent overrides the upwelling and subduction in its classical form stops. The third stage appears only in the upper mantle model with localized upwellings. ?? 2006 The Authors Journal compilation ?? 2006 RAS.

  8. Formation of tectonic peperites from alkaline magmas intruded into wet sediments in the Beiya area, western Yunnan, China

    NASA Astrophysics Data System (ADS)

    Xu, Xing-Wang; Cai, Xin-Ping; Zhong, Jia-You; Song, Bao-Chang; Peters, Stephen G.

    2007-08-01

    Tertiary (3.78 Ma to 3.65 Ma) biotite-K-feldspar porphyritic bodies intrude Tertiary, poorly consolidated lacustrine sedimentary rocks in the Beiya mineral district in southwestern China. The intrusives are characterized by a microcrystalline and vitreous-cryptocrystalline groundmass, by replacement of some tabular K-feldspar phenocrysts with microcrystalline chlorite and calcite, and by Fe-rich rings surrounding biotite phenocrysts. Peculiar structures, such as contemporary contact faults and slickensides, ductile shear zones and flow folds, foliation and lineations, tension fractures, and banded and boudin peperites, are developed along the contact zones of the intrusives. These features are related to the forceful intrusion of the alkaline magmas into the wet Tertiary sediments. The partially consolidated magmas were deformed and flattened by continued forceful magma intrusion that produced boudinaged and banded peperites. These peperites characterized by containing oriented deformation fabrics are classified as tectonic peperites as a new type of peperite, and formation of these tectonic peperites was related to fracturing of magmas caused by forceful intrusion and shear deformation and to contemporary migration and injection of fluidized sediments along fractures that dismembered the porphyritic magma. Emplacement of the magma into the wet sediments in the Beiya area is interpreted to be related to a large pressure difference rather than to the buoyancy force.

  9. Formation of tectonic peperites from alkaline magmas intruded into wet sediments in the Beiya area, western Yunnan, China

    USGS Publications Warehouse

    Xu, X.-W.; Cai, X.-P.; Zhong, J.-Y.; Song, B.-C.; Peters, S.G.

    2007-01-01

    Tertiary (3.78 Ma to 3.65 Ma) biotite-K-feldspar porphyritic bodies intrude Tertiary, poorly consolidated lacustrine sedimentary rocks in the Beiya mineral district in southwestern China. The intrusives are characterized by a microcrystalline and vitreous-cryptocrystalline groundmass, by replacement of some tabular K-feldspar phenocrysts with microcrystalline chlorite and calcite, and by Fe-rich rings surrounding biotite phenocrysts. Peculiar structures, such as contemporary contact faults and slickensides, ductile shear zones and flow folds, foliation and lineations, tension fractures, and banded and boudin peperites, are developed along the contact zones of the intrusives. These features are related to the forceful intrusion of the alkaline magmas into the wet Tertiary sediments. The partially consolidated magmas were deformed and flattened by continued forceful magma intrusion that produced boudinaged and banded peperites. These peperites characterized by containing oriented deformation fabrics are classified as tectonic peperites as a new type of peperite, and formation of these tectonic peperites was related to fracturing of magmas caused by forceful intrusion and shear deformation and to contemporary migration and injection of fluidized sediments along fractures that dismembered the porphyritic magma. Emplacement of the magma into the wet sediments in the Beiya area is interpreted to be related to a large pressure difference rather than to the buoyancy force. ?? 2007 Elsevier Ltd. All rights reserved.

  10. Active Tectonics In The Rukwa Rift (sw Tanzania): A Study of The Potential For Large Earthquakes In A Continental Rift.

    NASA Astrophysics Data System (ADS)

    Kervyn, F.

    The Rukwa rift is a deep sedimentary basin that is considered as a tectonic trans- fer zone between the Tanganyika and the Malawi troughs. The tectonic evolution of the depression is controlled by the reactivation of proterozoic structures and started with the deposition of the permo-triasic Karoo sediments. In the southeast, the rift is divided into two facing half graben separated by a Precambrian horst, whereas its northwestern part has a more symmetrical graben structure. Although most of the vertical displacement is accommodated by the Lupa eastern boundary fault, onshore shallow seismic profiles have confirmed the co-occurrence of intrabasin synthetic- and strike-slip faults within the sub surface sediments. Both normal and dextral strike-slip movement are indeed observed in the basin in response to the E-W to WNW-SSE ex- tension. The region has a moderate seismic activity and the earthquakes magnitude is generally below M 6.5. However, a M 7.4 earthquake occurred in the Rukwa region in 1910 but its exact location remains uncertain. The current research aimed at the identi- fication of active faults within the recent deposits of the basin by the combination in a GIS of radar interferometric data with topographical and geological maps, geophysical data, and field observations. Radar interferometry (InSAR) was found to be especially suitable for DEM computation in low relief areas where available topographic data are limited in accuracy. Numerous topographic lineaments were observed on InSAR DEM, and follow two main directions, both oblique to the main NW-SE trend of the rift. On the one hand, the GIS analysis confirms that the observed lineaments corre- spond to real natural alignment such like the drainage for example, and are therefore not related to atmospheric artefacts. On the other hand, the field observations revealed that in most cases, the topographic lineaments are very subtle and difficult to identify. However, direct correlations with tectonic

  11. Tectonic activity revealed by morphostructural analysis: Development of the Sierra de la Candelaria range, northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Barcelona, H.; Peri, G.; Tobal, J.; Sagripanti, L.; Favetto, A.

    2014-12-01

    The tectonically active broken foreland of NW Argentina is a recent analog of the eastern margin of the Puna plateau during Mio-Pliocene times and likely of other broken forelands worldwide. In order to evaluate active tectonism in the broken foreland of the NW Argentine Andes, we examined the complex geomorphology in the vicinity of the basement-cored Sierra de la Candelaria range at ˜26°S and deciphered multiple episodes of crustal deformation spanning the Pliocene to the Quaternary. Digital elevation models, satellite images and geological data within a GIS environment allowed us to analyze the terrain, drainage networks, river dynamics and structure, as well as to obtain detailed geomorphological mapping, active tectonic indices, longitudinal river profiles and structural sections. Three morphostructural segments were defined based on the structural features, the differential vertical dissection pattern over the basement, the faulted Pliocene to recent deposits, the stepwise propagation of anticlines and the distortion over the fluvial system. By combining the several lines of evidence, we concluded that the Sierra de la Candelaria range was subjected to a multi-stage development. The first stage uplifted the central segment concomitant with the formation of the surrounding ranges and with the main partition phase of the foreland. After a significant time lapse, the mountain range was subjected to southward thick-skinned growth and northward growth via stepwise thin-skinned deformation and exerted control over the dynamics of the Río Rosario. Taking into account the surrounding basins and ranges of the Sierra de la Candelaria, the southern Santa Bárbara System is characterized by partially isolated intramontane basins (Choromoro and Rosario) limited by shielded ranges that caused moisture block and shows continuous deformation. These features were related to early stages of a broken foreland evolution model and modern analogs were found at the northern

  12. Oblique Convergence Tectonics in Northern Taiwan-Ryukyu Area:Insights from Sandbox Modeling

    NASA Astrophysics Data System (ADS)

    Li, Z.; Lu, C. Y.

    2015-12-01

    Taiwan located on the boundary between Eurasian Plate and Philippine Sea Plate and as a results of convergence of these two plates. The specific process of Taiwan orogeny is a hot issue for many years. Sandbox modeling is a way to simulate the mountain building process. The previous studies of 3D sandbox modeling in Taiwan are more concentrated on the effect of basement high and arc-continent collision but few noted the effect of opening of Okinawa Trough. This 3D experiment aims at the structure of northern Taiwan, adds a sandpaper machine which could move in experiment that simulate the opening of Okinawa Trough, and tries to explain the tectonic evolution in northern Taiwan. Result of experimental modeling proves that: (1) the Ryukyu Arc is pulled apart and moving southward as the opening of Okinawa Trough, (2) direction of Ryukyu Arc changed between southern part and middle-northern part due to the opening of Okinawa Trough, (3) Ilan Plain subsidence caused by the opening of Okinawa Trough.

  13. Ganges-Brahmaputra Delta: Balance of Subsidence, Sea level and Sedimentation in a Tectonically-Active Delta (Invited)

    NASA Astrophysics Data System (ADS)

    Steckler, M. S.; Goodbred, S. L.; Akhter, S. H.; Seeber, L.; Reitz, M. D.; Paola, C.; Nooner, S. L.; DeWolf, S.; Ferguson, E. K.; Gale, J.; Hossain, S.; Howe, M.; Kim, W.; McHugh, C. M.; Mondal, D. R.; Petter, A. L.; Pickering, J.; Sincavage, R.; Williams, L. A.; Wilson, C.; Zumberge, M. A.

    2013-12-01

    Bangladesh is vulnerable to a host of short and long-term natural hazards - widespread seasonal flooding, river erosion and channel avulsions, permanent land loss from sea level rise, natural groundwater arsenic, recurrent cyclones, landslides and huge earthquakes. These hazards derive from active fluvial processes related to the growth of the delta and the tectonics at the India-Burma-Tibet plate junctions. The Ganges and Brahmaputra rivers drain 3/4 of the Himalayas and carry ~1 GT/y of sediment, 6-8% of the total world flux. In Bangladesh, these two great rivers combine with the Meghna River to form the Ganges-Brahmaputra-Meghna Delta (GBMD). The seasonality of the rivers' water and sediment discharge is a major influence causing widespread flooding during the summer monsoon. The mass of the water is so great that it causes 5-6 cm of seasonal elastic deformation of the delta discerned by our GPS data. Over the longer-term, the rivers are also dynamic. Two centuries ago, the Brahmaputra River avulsed westward up to 100 km and has since captured other rivers. The primary mouth of the Ganges has shifted 100s of km eastward from the Hooghly River over the last 400y, finally joining the Brahmaputra in the 19th century. These avulsions are influenced by the tectonics of the delta. On the east side of Bangladesh, the >16 km thick GBMD is being overridden by the Burma Arc where the attempted subduction of such a thick sediment pile has created a huge accretionary prism. The foldbelt is up to 250-km wide and its front is buried beneath the delta. The main Himalayan thrust front is <100 km north, but adjacent to the GBMD is the Shillong Massif, a 300-km long, 2-km high block of uplifted Indian basement that is overthrusting and depressing GBMD sediments to the south. The overthrusting Shillong Massif may represent a forward jump of the Himalayan front to a new plate boundary. This area ruptured in a ~M8 1897 earthquake. Subsidence from the tectonics and differential

  14. Primary centers and secondary concentrations of tectonic activity through time in the western hemisphere of Mars

    USGS Publications Warehouse

    Anderson, R.C.; Dohm, J.M.; Golombek, M.P.; Haldemann, A.F.C.; Franklin, B.J.; Tanaka, K.L.; Lias, J.; Peer, B.

    2001-01-01

    Five main stages of radial and concentric structures formed around Tharsis from the Noachian through the Amazonian as determined by geologic mapping of 24,452 structures within the stratigraphic framework of Mars and by testing their radial and concentric orientations. Tectonic activity peaked in the Noachian (stage 1) around the largest center, Claritas, an elongate center extending more than 20?? in latitude and defined by about half of the total grabens which are concentrated in the Syria Planum, Thaumasia, and Tempe Terra regions. During the Late Noachian and Early Hesperian (stage 2), extensional structures formed along the length of present-day Valles Marineris and in Thaumasia (with a secondary concentration near Warrego Vallis) radial to a region just to the south of the central margin of Valles Marineris. Early Hesperian (stage 3) radial grabens in Pavonis, Syria, Ulysses, and Tempe Terra and somewhat concentric wrinkle ridges in Lunae and Solis Plana and in Thaumasia, Sirenum, Memnonia, and Amazonis are centered northwest of Syria with secondary centers at Thaumasia, Tempe Terra, Ulysses Fossae, and western Valles Marineris. Late Hesperian/Early Amazonian (stage 4) structures around Alba Patera, the northeast trending alignment of Tharsis Montes, and Olympus Mons appears centered on Alba Patera. Stage 5 structures (Middle-Late Amazonian) represent the last pulse of Tharsis-related activity and are found around the large shield volcanoes and are centered near Pavonis Mons. Tectonic activity around Tharsis began in the Noachian and generally decreased through geologic time to the Amazonian. Statistically significant radial distributions of structures formed during each stage, centered at different locations within the higher elevations of Tharsis. Secondary centers of radial structures during many of the stages appear related to previously identified local magmatic centers that formed at different times and locations throughout Tharsis. Copyright 2001 by

  15. Flare-Shaped Acoustic Anomalies in the Water Column Along the Ecuadorian Margin: Relationship with Active Tectonics and Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Michaud, Francois; Proust, Jean-Noël; Dano, Alexandre; Collot, Jean-Yves; Guiyeligou, Grâce Daniella; Hernández Salazar, María José; Ratzov, Gueorgui; Martillo, Carlos; Pouderoux, Hugo; Schenini, Laure; Lebrun, Jean-Frederic; Loayza, Glenda

    2016-10-01

    With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to the shelf break (140 m). Nearly half of the flare-shaped acoustic anomalies rise 200-500 m above the seafloor. The base of the flares is generally associated with high-reflectivity backscatter patches contrasting with the neighboring seafloor. We interpret these flares as caused by fluid escape in the water column, most likely gases. High-resolution seismic profiles show that most flares occur close to the surface expression of active faults, deformed areas, slope instabilities or diapiric structures. In two areas tectonic deformation disrupts a Bottom Simulating Reflector (BSR), suggesting that buried frozen gas hydrates are destabilized, thus supplying free gas emissions and related flares. This discovery is important as it opens the way to determine the nature and origin of the emitted fluids and their potential link with the hydrocarbon system of the forearc basins along the Ecuadorian margin.

  16. Flare-Shaped Acoustic Anomalies in the Water Column Along the Ecuadorian Margin: Relationship with Active Tectonics and Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Francois, Michaud; Noël, Proust Jean; Alexandre, Dano; Yves, Collot Jean; Daniella, Guiyeligou Grâce; José, Hernández Salazar María; Gueorgui, Ratzov; Carlos, Martillo; Hugo, Pouderoux; Laure, Schenini; Frederic, Lebrun Jean; Glenda, Loayza

    2016-01-01

    With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to the shelf break (140 m). Nearly half of the flare-shaped acoustic anomalies rise 200-500 m above the seafloor. The base of the flares is generally associated with high-reflectivity backscatter patches contrasting with the neighboring seafloor. We interpret these flares as caused by fluid escape in the water column, most likely gases. High-resolution seismic profiles show that most flares occur close to the surface expression of active faults, deformed areas, slope instabilities or diapiric structures. In two areas tectonic deformation disrupts a Bottom Simulating Reflector (BSR), suggesting that buried frozen gas hydrates are destabilized, thus supplying free gas emissions and related flares. This discovery is important as it opens the way to determine the nature and origin of the emitted fluids and their potential link with the hydrocarbon system of the forearc basins along the Ecuadorian margin.

  17. The QuakeSim Project: Numerical Simulations for Active Tectonic Processes

    NASA Technical Reports Server (NTRS)

    Donnellan, Andrea; Parker, Jay; Lyzenga, Greg; Granat, Robert; Fox, Geoffrey; Pierce, Marlon; Rundle, John; McLeod, Dennis; Grant, Lisa; Tullis, Terry

    2004-01-01

    In order to develop a solid earth science framework for understanding and studying of active tectonic and earthquake processes, this task develops simulation and analysis tools to study the physics of earthquakes using state-of-the art modeling, data manipulation, and pattern recognition technologies. We develop clearly defined accessible data formats and code protocols as inputs to the simulations. these are adapted to high-performance computers because the solid earth system is extremely complex and nonlinear resulting in computationally intensive problems with millions of unknowns. With these tools it will be possible to construct the more complex models and simulations necessary to develop hazard assessment systems critical for reducing future losses from major earthquakes.

  18. Tracking tectonic activity and climate change in Southernmost Patagonia - The Lago Fagnano record

    NASA Astrophysics Data System (ADS)

    Waldmann, N.; Ariztegui, D.; Anselmetti, F. S.; Austin, J. A.; Moy, C.; Dunbar, R.

    2005-12-01

    The climate of southernmost Patagonia is influenced by the westerly winds, the Southern Ocean circumpolar flow, and the South Pacific gyre. Therefore, continental sediment records from this area are ideal to track high-latitude climate variability through time. Located at 55° S in Tierra del Fuego, Lago Fagnano occupies the deepest of a chain of tectonic depressions along the Fagnano-Magallanes fault system. Fagnano is the biggest (~110 km long), southernmost non-ice covered lake in the world. In March 2005, >800 km of geophysical data were acquired in the lake, combining simultaneously 3.5 kHz (pinger) single-channel with 1 in3 airgun multi-channel systems. These data provide a unique opportunity to look at the most recent lacustrine sediments with high-resolution, while imaging the oldest sediments at the same time. Preliminary interpretations show that the lake is divided into two sub-basins: a deep eastern sub-basin (~200 m water depth), and a shallower western sub-basin (~100 m). The seismic survey penetrated more than several tens of meters of sediments, exhibiting both lacustrine and glacial provenance, probably comprising the LGM and the Holocene. Seismic reflectors indicate the presence of neo-tectonic structures affecting even the most recent sedimentary package, including some mega-turbidites, suggesting continuing tectonic impact on sedimentation. Gravity cores from both sub-basins reveal a regular alternation of light and dark laminae with abundant diatom content. Ultra-high resolution X-ray fluorescence micro-profiles show fluctuations at mm scale in major and trace elements that may indicate seasonal influx changes into the basin. These core data will provide a unique record of decadal changes in regional climate that will be compared with other marine and continental archives to improve our understanding of the forcing mechanisms behind climate change that can be further used to validate the outcome of ocean and atmospheric climatic models for the

  19. Geochonology and Tectonic Significance of post-collisional porphyry in Qulong area, southeast segment of the Gangdese belt, Tibet, China

    NASA Astrophysics Data System (ADS)

    Liu, D.; Zeren, Z.; Du, C.; Feng, L.; Nima, C.; Zhang, L.

    2012-12-01

    With the collision of Indian plate and Eura-Asian plate, there developed complicated tectono-magmanism during Meso-Cenozoic in Gangdese belt, Xizang Tibet. Therefore, it resulted that plentiful tectonism and post-collision high-K calc-alkaline magmatism related to mineralization distrubted from east to west in the belt. And this is quite significant for us to do some rearch on large-scale metallogenetics, uplifting epoch and EW-striking extension during the post-collision in Xizang-Qinghai Plateau. Zircon samples from Cangrila Granodiorite-porphyry in Qulong area, Southeast of Gangdese porphyry copper belt, Xiangbeishan diorite-porphyrite and from Jiama Granite-porphyry give LA-ICPMS U-Pb ages of 16.3Ma, 14. 4Ma, and 15.4Ma, respectively, and all these ages represent the porphyries' forming ages. From barren Xiangbeishan diorite-porphyrite through intermediately mineralized Jiama Granite-porphyry to stongly mineralized Cangrila Granodiorite-porphyry, the LA-ICPMS U-Pb ages of zircon become younger and younger. According to the regional data and geochemical characteristics, these porphyries were mainly derived directly from the thickened mafic lower-crust formed in south Tibet during collision and epeirogeny. During post-collisional extension stage, for inter-earth thermal flowing, SN-striking normal faulting systems across the Tibetan orogen caused rapid rising and localization of porphyry magmas and adequately separating of massive ore-bearing fluids from the magmatic hydrothermal systems. All these data indicate that Gandese belt has experienced from post-collisional extrusion changed into intra-plate extension since Miocene. During Miocene, Gangdese belt undergone violent intraplate extension, post-collisional porphyry intrusion and paroxysmal massive mineralization of porphyry-type, and all these was controlled by deep dynamics. Key Words: Qulong area; Gangdese tectonic belt; Tibet;Zircon La-ICP-MS U-Pb dating; intra-plate extension; Image Information For CL

  20. Early Mesozoic reconstructions, tectonics and paleogeography of Caribbean-Gulf of Mexico-Atlantic area

    SciTech Connect

    Wiener, R.W.; Norton, I.O.

    1985-01-01

    Five plate reconstructions with paleogeography show the evolution of the Gulf of Mexico-Caribbean-Atlantic from Late Triassic through Late Jurassic time. The reconstructions are constrained by oceanic geophysical data, by the distribution of Paleozoic tectonic belts and early Mesozoic sedimentary and igneous rocks, and by restoration of post-Jurassic faulting. Late Triassic rifting formed grabens in which continental sediments and tholeiitic volcanics accumulated. Overlying salt was deposited from ingression of Tethyan waters into circum-Atlantic grabens. Oceanic crust formed in the Atlantic about 165 m.y. ago, followed by a spreading-center jump about 160 m.y. ago. The NA/SA-Africa plate boundary was a zone of intracontinental faulting from the left-lateral Bahama fracture zone to a zone of normal and strike-slip faulting in the Gulf, to the left-lateral Mojave-Sonora megashear. Sea-floor spread in began in the proto-Caribbean in the middle Jurassic, while only rifting occurred in the Gulf of Mexico, where the Louann salt was deposited from Pacific waters. In the late Jurassic, steepening of the Pacific subduction zone resulted ion back-arc extension in Mexico. At the same time, sea-floor spreading began in the Gulf of Mexico, resulting in marine transgression. In the late Oxfordian, spreading center reorganization occurred in the Gulf. Movement ceased on the Mojave-Sonora megashear and began on the Salina Cruz right-lateral fault. In latest Jurassic spreading ceased in the Gulf, but continued in the proto-Caribbean.

  1. Active tectonic deformation along rejuvenated faults in tropical Borneo: Inferences obtained from tectono-geomorphic evaluation

    NASA Astrophysics Data System (ADS)

    Mathew, Manoj Joseph; Menier, David; Siddiqui, Numair; Kumar, Shashi Gaurav; Authemayou, Christine

    2016-08-01

    The island of Borneo is enveloped by tropical rainforests and hostile terrain characterized by high denudation rates. Owing to such conditions, studies pertaining to neotectonics and consequent geomorphic expressions with regard to surface processes and landscape evolution are inadequately constrained. Here we demonstrate the first systematic tectono-geomorphic evaluation of north Borneo through quantitative and qualitative morphotectonic analysis at sub-catchment scale, for two large drainage basins located in Sarawak: the Rajang and Baram basins. The extraction of morphometric parameters utilizing digital elevation models arranged within a GIS environment focuses on hypsometric curve analysis, distribution of hypsometric integrals through spatial autocorrelation statistics, relative uplift values, the asymmetry factor and the normalized channel steepness index. Hypsometric analysis suggests a young topography adjusting to changes in tectonic boundary conditions. Autocorrelation statistics show clusters of high values of hypsometric integrals as prominent hotspots that are associated with less eroded, young topography situated in the fold and thrust belts of the Interior Highlands of Borneo. High channel steepness and gradients (> 200 m0.9) are observed in zones corresponding to the hotspots. Relative uplift values reveal the presence of tectonically uplifted blocks together with relatively subsided or lesser uplifted zones along known faults. Sub-catchments of both basins display asymmetry indicating tectonic tilting. Stream longitudinal profiles demonstrate the presence of anomalies in the form of knickzones without apparent lithological controls along their channel reaches. Surfaces represented by cold spots of low HI values and low channel gradients observed in the high elevation headwaters of both basins are linked to isolated erosional planation surfaces that could be remnants of piracy processes. The implication of our results is that Borneo experiences

  2. Can deep seated gravitational slope deformations be activated by regional tectonic strain: First insights from displacement measurements in caves from the Eastern Alps

    NASA Astrophysics Data System (ADS)

    Baroň, Ivo; Plan, Lukas; Grasemann, Bernhard; Mitroviċ, Ivanka; Lenhardt, Wolfgang; Hausmann, Helmut; Stemberk, Josef

    2016-04-01

    Tectonic elastic strain and ground deformations are documented as the most remarkable environmental phenomena occurring prior to local earthquakes in tectonically active areas. The question arises if such strain would be able to trigger mass movements. We discuss a directly observed fault slip and a subsequent minor activation of a deep-seated gravitational slope deformation prior to the M = 3 Bad Fischau earthquake between end of November and early December 2013 in NE Austria. The data originate from two faults in the Emmerberg and Eisenstein Caves in the transition zone between the Eastern Alps and the Vienna Basin, monitored in the framework of the FWF "Speleotect" project. The fault slips have been observed at the micrometer-level by means of an opto-mechanical 3D crack gauge TM-71. The discussed event started with the fault activation in the Emmerberg Cave on 25 November 2013 recorded by measurements of about 2 μm shortening and 1 μm sinistral parallel slip, which was fully in agreement with the macroscopically documented past fault kinematics. One day later, the mass (micro) movement activated on the opposite side of the mountain ridge in the Eisenstein Cave and it continued on three consecutive days. Further, the fault in the Emmerberg Cave experienced also a subsequent gravitational relaxation on 2/3 December 2013, when the joint opened and the southern block subsided towards the valley, while the original sinistral displacement remained irreversible. The process was followed by the M = 3 earthquake in Bad Fischau on 11 December 2013. Our data suggest that tectonic strain could play a higher role on the activation of slow mass movements in the area than expected. Although we cannot fully exclude the co-activation of the mass movement in the Eisenstein Cave by water saturation, the presented data bring new insight into recent geodynamics of the Eastern Alps and the Vienna Basin. For better interpretations and conclusions however, we need a much longer

  3. Meso-cenozoic volcanic rocks in east China and adjacent areas with relation to plate tectonics

    NASA Astrophysics Data System (ADS)

    Zheng, Xuezheng

    1985-03-01

    Meso-Cenozoic calc-alkaline volcanic rocks and granites in the East China region are composed of four NE belts from west to east; the Trassic belt in the middle and east Mongolia, the Jurassic-Creta-ceous belt in East China, the Paleogene belt in the East China Sea and the Neogene-Quaternary belt in southwestern Japan-Okinawa and northeastern Japan-Izu-Bonin-Mariana volcanic arcs. They are nearly parallel to the Benioff zones of the ancient Pacific Plate on one hand and become older as the distance from the Pacific Ocean increases on the other hand. This sequence is in reverse order to that in South and North America. There are two age-peaks among them: one is in the early Cretaceous and the other in the Miocene, in good agreement with the time when the sea-floor spreading of the ancient Pacific Plate became fast during 115-85 Ma and after 25 Ma (Hilde et al., 1977). The second belt in East China consists of three paralleled NE sub-belts and two E-W sub-belts on which the volcanoes erupted throughout the Jurassic-Cretaceous period but the strong eruption centres were moving eastward with time. The continental rift-type basalts occurred in the middle of East China in Paleogene time. The Neogene-Quaternary basalts in East China belong to crack-type (Zheng and Zao, 1984). These ages and types of rocks suggest that subduction of the ancient Pacific Plate began at Triassic time and became stronger later. The Meso-Cenozoic volcanic belts, from north to south, can be divided into three different regions by the Tianshan-Xinganling and the Qinling tectonic lines in the middle of East Asia and two regions in the middle of the western Pacific. This difference has been getting clear since the Triassic time. On the whole, the Meso-Cenozoic volcanism in the middle of the western Pacific records reaction between the Asian Plate and the ancient Pacific Plate or the Indian Plate.

  4. Tectonic stratigraphy near a metamorphic core complex: Lessons from the Castaneda-signal area of west-central Arizona

    SciTech Connect

    Lucchitta, I. ); Suneson, N.H. )

    1993-04-01

    A sequence of latest Oligocene through Quaternary sedimentary and volcanic rocks, when analyzed tectonically and combined with lithologically distinctive source terranes, clarifies the character and timing of Neogene extension just north of the Buckskin-Rawhide metamorphic core complex (BRMCC) in west-central Arizona. The oldest strata (basal arkose of Lucchitta and Suneson) reflect regional stability and a southwesterly paleoslope. In latest Oligocene time, this drainage was ponded by an upwarp (now exposed as the BRMCC) rising to the southwest. The resulting lake beds contain a thin 26.6 MA airfall tuff that marks the beginning of volcanic activity in the region. A widespread breccia records the progressive unroofing of the still-rising CC. Mantle-driven crustal heating probably caused the upwarp and allowed the eruption of voluminous mantle-derived basalt and basaltic andesite about 19 MA (early basalts, Artillery Basalt). The overlying syntectonic conglomerate (arkose of Keenan Camp) was deposited during a period of extreme extension, low-angle detachment faulting, and block rotation, typical of highly extended terranes. The conglomerate is interlayered with widespread silicic volcanic rocks (15--10 MA) derived from the lower crust and large gravity-glide sheets lithologically identical to the breccia and similarly derived from the CC to the south. Unconformably overlying the conglomerate are locally derived fanglomerate and 13--8.5 MA (mesa-forming) basalt that accumulated in present-day basins of classic basin-range type. Untilted and nearly unfaulted 7.7--5.4 MA mantle-derived megacryst-bearing basalt marks the cessation of tectonic activity.

  5. Relative tectonic activity assessment along the East Anatolian strike-slip fault, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Khalifa, Abdelrahman

    2016-04-01

    The East Anatolian transform fault is a morphologically distinct and seismically active left-lateral strike-slip fault that extends for ~ 500 km from Karlıova to the Maraş defining the boundary between the Anatolian Block and Syrian Foreland. Deformed landforms along the East Anatolian fault provide important insights into the nature of landscape development within an intra-continental strike-slip fault system. Geomorphic analysis of the East Anatolian fault using geomorphic indices including mountain front sinuosity, stream length-gradient index, drainage density, hypsometric integral, and the valley-width to valley height ratio helped differentiate the faulting into segments of differing degrees of the tectonic and geomorphic activity. Watershed maps for the East Anatolian fault showing the relative relief, incision, and maturity of basins along the fault zone help define segments of the higher seismic risk and help evaluate the regional seismic hazard. The results of the geomorphic indices show a high degree of activity, reveal each segment along the fault is active and represent a higher seismic hazard along the entire fault.

  6. Intermittent Plate Tectonics

    NASA Astrophysics Data System (ADS)

    Silver, P. G.; Behn, M. D.

    2006-12-01

    Intermittent Plate Tectonics A basic premise of Earth Science is that plate tectonics has been continuously operating since it began early in Earth's history. Yet, plate-tectonic theory itself, specifically the collisional phase of the Wilson Cycle, constitutes a process that is capable of stopping all plate motion. The plausibility of a plate-tectonic hiatus is most easily illustrated by considering the expected future of the present-day plate-tectonic configuration. Since the opening of the Atlantic at ~200 ma, the area of the Atlantic basin has been growing at the expense of the Pacific. If this trend continues, relative plate motion models predict that in ~350 my, the Pacific Ocean basin will effectively close leading to widespread continent-continent collisions. Since a continent-continent collision represents the termination of subduction locally, the accumulated effect of all collisions is to stop subduction globally. In this scenario, ridges would then stop spreading and young oceanic lithosphere would cool, reaching a steady-state thickness of 100 km in about 80 my, based on the properties of oceanic lithosphere today. This would constitute the stoppage of plate tectonics. The presumption that plate tectonics never stops in the face of continental collisions is equivalent to requiring that subduction flux is approximately constant through time, such that subduction initiation roughly balances subduction termination. Such a balance then raises several questions about the subduction initiation process. When and how does subduction initiate? Is there a detectible relationship between subduction cessation and subduction initiation? We can gain some guidance into these questions by examining the plate motion history over the last 200 my. Subduction initiation has occurred over the last 80 my in three intra- oceanic subduction zones: Aleutians, Marianas-Izu-Bonin and Tonga-Kermadec in the Pacific basin. In these cases, however, subduction initiation would not

  7. Tectonic evolution of the India-Asia suture zone since Middle Eocene time, Lopukangri area, south-central Tibet

    NASA Astrophysics Data System (ADS)

    Sanchez, V. I.; Murphy, M. A.; Robinson, A. C.; Lapen, T. J.; Heizler, M. T.

    2013-01-01

    Suture zones often archive complex geologic histories underscored by episodes of varying style of deformation associated with intercontinental collision. In the Lopukangri area of south-central Tibet (29°54'N, 84°24'E) field relationships between tectonic units juxtaposed by the India-Asia suture are well exposed, including Indian passive margin rocks (Tethyan Sedimentary Sequence), forearc deposits (Xigaze Group), magmatic arc rocks (Gangdese batholith and Linzizong Formation) and syncollision deposits (Eocene-Miocene conglomerates). To better understand the structural history of this area, we integrated geologic mapping with biotite 40Ar/39Ar thermochronology and zircon U-Pb geochronology. The first-order structure is a system of north-directed thrusts which are part of the Great Counter thrust (GCT) that places Indian passive margin rocks and forearc deposits on top of magmatic arc rocks and syn-tectonic conglomerates. We infer the south-directed Late Oligocene Gangdese Thrust (GT) exists at unexposed structural levels based on field mapping, cross sections, and regional correlations as it has been documented immediately to the east. A granite in the footwall has a U-Pb zircon age of 38.4 ± 0.4 Ma, interpreted to be the age of emplacement of the granite, and a younger 40Ar/39Ar biotite age of 19.7 ± 0.1 Ma. As the granite sample is situated immediately below a nonconformity with low grade greenschist facies rocks, we interpret the younger age to reflect Miocene resetting of the biotite Ar system. Syn-tectonic deposits in the Lopukangri area consist of three conglomerate units with a total thickness of ˜1.5 km. The lower two units consist of cobble gravel pebble conglomerates rich in volcanic and plutonic clasts, transitioning to conglomerates with only sedimentary clasts in the upper unit. We correlate the syncollision deposits to the Eocene-Oligocene Qiuwu Formation based on field relationships, stratigraphy and petrology. Petrology and clast composition

  8. Geomorphic evidence of possible tectonic activity in the Mississippi embayment of southeast Missouri

    SciTech Connect

    Steckel, P.J.

    1993-03-01

    Several distinct topographic and geomorphic features in the Mississippi Embayment of southeast Missouri may provide direct and indirect evidence of tectonic influence on surface processes. First, the Pascola bulge is an extremely subtle feature, which probably trends northwest from about Caruthersville to northeast of Kennett and may or may not be associated with the Pascola Arch. The Pascola bulge may be responsible for an abrupt change in both the direction and meander pattern of the natural channel of the Little river near Wardell; a bifurcation of the natural channel of the Little river west of Wardell; the closing off of a natural, navigable waterway between the Mississippi and St. Francis rivers (in the early 1800s); and, at least partly, the extremely inefficient Caruthersville Bend of the Mississippi River. Second, the Canalou nickpoint is an abrupt and distinct change in slope that coincides with both a series of northwest-trending surface lineaments and a southeast projection of the Black fault, located in the Paleozoic rock of the Ozark Uplift. The Canalou nickpoint may suggest a structural feature in the area west of Sikeston. Finally, a subtle yet distinctly irregular surface topography and the near obliteration of topographic expression of the natural channel of the Little River suggest that sunklands may have occurred in areas southeast of Kennett and from near Hornersville south to at least the Missouri-Arkansas state line.

  9. Impact of the Yakutat indentor corner on present-day tectonics and fault activity in SE Alaska - SW Yukon

    NASA Astrophysics Data System (ADS)

    Mazzotti, S.; Marechal, A.; Ritz, J. F.; Ferry, M. A.

    2015-12-01

    We present an active tectonic model of the SE Alaska - SW Yukon region based principally on the integration of recent GPS velocity data and new fault-slip rates derived from geomorphology. In this region, the Yakutat collision results in complex tectonics with patterns of strain localization and strain partitioning that strongly vary across the various mountain ranges and active faults. We propose that deformation and fault activity in the St. Elias and Chugach Mountains are primarily controlled by the eastern syntaxis of the Yakutat collision, which produces a semi-radial tectonic pattern: Velocities, principal horizontal shortening rates, and maximum horizontal stress orientations rotate by 60 - 80 ° around the syntaxis, from roughly parallel to the relative Pacific - North America motion at the front of the collision to roughly orthogonal southeast of the syntaxis. The interaction between this strain pattern and major inherited tectonic structures inland of the collision zone (i.e., Denali and Duke River Faults) results in various reactivation modes of these structures. Specifically, the Denali Fault shows a very pronounced lateral variations of activity from ~12 mm/a of dextral slip rate in its central section to ~1 mm/a of mostly shortening slip rate along its southern section. This marked change of activity is associated with a possible relay system where the Duke River and Totschunda Faults accommodate a major part (8 - 12 mm/a) of the inland strain transfer directly in front of the syntaxis. This new tectonic model retains some questions, in particular regarding the mechanisms of deformation and strain transfer (1) from the syntaxis to the Duke River - Totschunda system and (2) at the junction between Totschunda and Denali Faults. Numerical models of present-day deformation may help address these issues and provide information about relative strength of the various crustal and inherited fault elements of this system.

  10. The Role of Plate Tectonic-Climate Coupling and Exposed Land Area in the Development of Habitable Climates on Rocky Planets

    NASA Astrophysics Data System (ADS)

    Foley, Bradford J.

    2015-10-01

    The long-term carbon cycle is vital for maintaining liquid water oceans on rocky planets due to the negative climate feedbacks involved in silicate weathering. Plate tectonics plays a crucial role in driving the long-term carbon cycle because it is responsible for CO2 degassing at ridges and arcs, the return of CO2 to the mantle through subduction, and supplying fresh, weatherable rock to the surface via uplift and orogeny. However, the presence of plate tectonics itself may depend on climate according to recent geodynamical studies showing that cool surface temperatures are important for maintaining vigorous plate tectonics. Using a simple carbon cycle model, I show that the negative climate feedbacks inherent in the long-term carbon cycle are uninhibited by climate's effect on plate tectonics. Furthermore, initial atmospheric CO2 conditions do not impact the final climate state reached when the carbon cycle comes to equilibrium, as long as liquid water is present and silicate weathering can occur. Thus an initially hot, CO2 rich atmosphere does not prevent the development of a temperate climate and plate tectonics on a planet. However, globally supply limited weathering does prevent the development of temperate climates on planets with small subaerial land areas and large total CO2 budgets because supply limited weathering lacks stabilizing climate feedbacks. Planets in the supply limited regime may become inhospitable for life and could experience significant water loss. Supply limited weathering is less likely on plate tectonic planets because plate tectonics promotes high erosion rates and thus a greater supply of bedrock to the surface.

  11. Recent Fluvial, Volcanic, and Tectonic Activity on the Cerberus Plains of Mars

    NASA Astrophysics Data System (ADS)

    Berman, Daniel C.; Hartmann, William K.

    2002-09-01

    Athabasca and Marte Valles lie on the Cerberus plains, between the young, lava-covered plains of Elysium Planitia and Amazonis Planitia. To test pre- MGS ( Mars Global Surveyor) suggestions of extremely young volcanic and fluvial activity, we present the first crater counts from MGS imagery, at resolutions (˜2-20 m/pixel) much higher than previously available. The most striking result, based on morphologic relations as well as crater counts from different stratigraphic units, is to confirm quantitatively that these channel systems are much younger than most other major outflow channels. The general region has an average model age for lava and fluvial surfaces of ≤200 Myr, and has possibly seen localized water releases, interspersed with lava flows, within the past 20 Myr. The youngest lavas may be no more than a few megayears old. Access of lava and liquid brines to the surface may be favored by openings of the Cerberus Fossae fracture system, but, as shown in the new images, the fractures appear to have continued developing more recently than the most recent lavas or fluvial activity. The Cerberus Fossae system may be an analog to an early stage of Valles Marineris, and its youthful activity raises questions about regional tectonic history. Large-volume water delivery to the surface of young lava flows in recent martian history puts significant boundary conditions on the storage and history of water on Mars.

  12. Geomorphic assessment of the tectonic activity of Qiulitagh fold-belt, Kuqa foreland basin, Xinjiang, China

    NASA Astrophysics Data System (ADS)

    Saint Carlier, Dimitri; Graveleau, Fabien; Delcaillau, Bernard; Hurtrez, Jean-Emmanuel; Vendeville, Bruno

    2014-05-01

    The Qiulitagh fold belt is an anticline structure located in the Kuqa fold-and-thrust belt (southern Tian Shan, China), whose active folding is well documented by structural and palaeomagnetic studies (Chen et al., 2007; Hubert-Ferrari et al., 2007; Li et al., 2012; Wang et al., 2011). The topography of Quilitagh fold belt can be divided into two SW-NE parallel ridges: 1) a 90 km long northern ridge, composed of the Northern Qiulitagh anticline and the Yakelike anticline, and 2) a 165km long southern ridge, composed of the Southern Qiulitagh anticline and the Mishikantage anticline. Due to the current absence of vegetation and relative homogeneity of outcropping lithologies (mainly Neogene detrital sandstone and silstone), these anticlines provide exceptional field cases for investigating the dynamic relationships between fold growth mechanisms, the subsurface structures, the geomorphic entities and the drainage network evolution. We used free topographic and satellite image datasets to carry out a morphometric study of the Quilitagh fold-belt and investigate the kinematics of active folding. Topographic datasets include Digital Elevation Models (DEM) from the NASA SRTM V.4.0 and ASTER programs, whereas satellite images are extracted from Landsat 7 shots and Google Earth. These datasets were incorporated in GIS software where three scales of observation were investigated: 1) a global fold scale, 2) a drainage basin scale and 3) a valley scale. At the drainage basin scale, we selected about 250 items and quantified several geomorphic indices of relative active tectonic growth. These are the basin mean slope, hypsometric integral, basin asymmetry and local relief. We also used published seismic profiles to link the 3D subsurface geometry of the salt-related Qiulitagh fold belt with the geomorphic signal. Results indicate that the morphometry of Quilitagh drainage basins (hypsometry, drainage basin asymmetry, local relief, valley incision, steepness index) change

  13. Late Paleozoic to Jurassic tectonic evolution of the Bogda area (northwest China): Evidence from detrital zircon U-Pb geochronology

    NASA Astrophysics Data System (ADS)

    Tang, Wenhao; Zhang, Zhicheng; Li, Jianfeng; Li, Ke; Chen, Yan; Guo, Zhaojie

    2014-06-01

    Since the Cenozoic, the Tian Shan is rejuvenated by crustal shortening related to the ongoing India-Asia collision. However, the tectonic process prior to the Cenozoic remains ambiguous, especially in the Bogda area of the eastern Tian Shan. The continuous Late Paleozoic-Mesozoic sequences in the Bogda area record abundant information about the basin-mountain interaction. U-Pb (LA-ICP-MS) dating of detrital zircons from seven sandstone samples from Permian to Jurassic was used to investigate the changes of provenance and basin-mountain interaction in the Bogda area. During the Permian, proximal and synchronous pyroclastic materials were the major source. The Late Paleozoic magmatic belt in the North Tian Shan (NTS) had gradually become one of the main sources by the Late Permian, which implies the uplift and exhumation in the NTS area. This is interpreted in terms of near-source sedimentation in basin developing in a post-orogenic extension setting. The large range of U-Pb ages of detrital zircons observed in the Early-Middle Jurassic sediments encompasses most of the available sources implying a wide drainage pattern developing on a rather flat topography. Re-emergence of the Early Permian peak in the spectrum implies that the Bogda Mountains has existed as a gentle positive relief and began to provide materials to the submountain regions. The southern Junggar Basin extended towards to the south and evolved as a passively subsiding basin from the Middle Triassic to the Middle Jurassic. However, the synchronous pyroclastic (tuff) and the exhumed late Paleozoic detrital materials from the uplifted Bogda Mountains were the major component of the Upper Jurassic sediments. Associated to the conglomerate in the Kalaza Formation, the basin-range evolution entered a compression uplift stage. The basin pattern evolution of the Bogda area is consistent with that of the southern Junggar Basin.

  14. Pore-pressure sensitivities to dynamic strains: observations in active tectonic regions

    USGS Publications Warehouse

    Barbour, Andrew

    2015-01-01

    Triggered seismicity arising from dynamic stresses is often explained by the Mohr-Coulomb failure criterion, where elevated pore pressures reduce the effective strength of faults in fluid-saturated rock. The seismic response of a fluid-rock system naturally depends on its hydro-mechanical properties, but accurately assessing how pore-fluid pressure responds to applied stress over large scales in situ remains a challenging task; hence, spatial variations in response are not well understood, especially around active faults. Here I analyze previously unutilized records of dynamic strain and pore-pressure from regional and teleseismic earthquakes at Plate Boundary Observatory (PBO) stations from 2006 through 2012 to investigate variations in response along the Pacific/North American tectonic plate boundary. I find robust scaling-response coefficients between excess pore pressure and dynamic strain at each station that are spatially correlated: around the San Andreas and San Jacinto fault systems, the response is lowest in regions of the crust undergoing the highest rates of secular shear strain. PBO stations in the Parkfield instrument cluster are at comparable distances to the San Andreas fault (SAF), and spatial variations there follow patterns in dextral creep rates along the fault, with the highest response in the actively creeping section, which is consistent with a narrowing zone of strain accumulation seen in geodetic velocity profiles. At stations in the San Juan Bautista (SJB) and Anza instrument clusters, the response depends non-linearly on the inverse fault-perpendicular distance, with the response decreasing towards the fault; the SJB cluster is at the northern transition from creeping-to-locked behavior along the SAF, where creep rates are at moderate to low levels, and the Anza cluster is around the San Jacinto fault, where to date there have been no statistically significant creep rates observed at the surface. These results suggest that the strength

  15. Stratigraphic assessment of the Arcelia Teloloapan area, southern Mexico: implications for southern Mexico's post-Neocomian tectonic evolution

    NASA Astrophysics Data System (ADS)

    Cabral-Cano, E.; Lang, H. R.; Harrison, C. G. A.

    2000-10-01

    Stratigraphic assessment of the "Tierra Caliente Metamorphic Complex" (TCMC) between Arcelia and Teloloapan in southern Mexico, based on photo interpretation of Landsat Thematic Mapper images and field mapping at the 1:100,000 scale, tests different tectonic evolution scenarios that bear directly on the evolution of the southern North American plate margin. The regional geology, emphasizing the stratigraphy of a portion of the TCMC within the area between Arcelia and Teloloapan is presented. Stratigraphic relationships with units in adjacent areas are also described. The base of the stratigraphic section is a chlorite grade metamorphic sequence that includes the Taxco Schist, the Roca Verde Taxco Viejo Formation, and the Almoloya Phyllite Formation. These metamorphic units, as thick as 2.7 km, are covered disconformably by a sedimentary sequence, 2.9 km thick, composed of the Cretaceous marine Pochote, Morelos, and Mexcala Formations, as well as undifferentiated Tertiary continental red beds and volcanic rocks. The geology may be explained as the evolution of Mesozoic volcanic and sedimentary environments developed upon attenuated continental crust. Our results do not support accretion of the Guerrero terrane during Laramide (Late Cretaceous-Paleogene) time.

  16. Implications for the tectonic transition zone of active orogeny in Hoping drainage basin, by landscape evolution at the multi-temporal timescale

    NASA Astrophysics Data System (ADS)

    Chang, Q.; Chen, R. F.; Lin, W.; Hsieh, P. S.

    2015-12-01

    In an actively orogeny the landscape are transient state of disequilibrium in response to climatic and tectonic inputs. At the catchment scale, sensitivity of river systems plays an important role in landscape evolution. Hoping drainage basin is located at the tectonic transition zone in the north-eastern Taiwan, where the behavior of Philippine Sea plate switches from overriding above the east-dipping Eurasian Continental plate to northward subducting under the Ryukyu arc. However, extensive deep-seated landslides, debris flow, and numerous large alluvial terraces can be observed, suggesting strong surface processes in this watershed. This effect on regional climate fundamentally changed the landscape by reconfiguring drainage patterns and creating a vast influx of sediments into the basin. In this study we review the morphological evidence from multi-temporal timescale, including in-situ cosmogenic nuclides denudation rate and suspension load data, coupled with the analysis of the longitudinal profiles. The main goal of this study is to compare Holocene erosion rates with thermochronology and radiometric dating of river terraces to investigate the erosion history of Hoping area. The result shows that short-term erosion rate is around twice as large as the long-term denudation rate, which might due to the climate-driven erosion events such as typhoon-induced landslide. We've also mapped detail morphological features by using the high-resolution LiDAR image, which help us to identify not only the landslide but also tectonic features such as lineation, fault scarps, and fracture zones. The tectonic surface features and field investigation results show that the drainage basin is highly fractured, suggesting that even though the vertical tectonic activity rate is small, the horizontal shortening influenced by both southward opening of the back-arc Okinawa trough and the north-western collision in this area is significant. This might cause the reducing in rock strength

  17. Seismicity at Uturuncu Volcano, Bolivia: Volcano-Tectonic Earthquake Swarms Triggered by the 2010 Maule, Chile Earthquake and Non-Triggered Background Activity

    NASA Astrophysics Data System (ADS)

    Christensen, D. H.; Chartrand, Z. A.; Jay, J.; Pritchard, M. E.; West, M. E.; McNutt, S. R.

    2010-12-01

    We find that the 270 ky dormant Uturuncu Volcano in SW Bolivia exhibits relatively high rates of shallow, volcano-tectonic seismicity that is dominated by swarm-like activity. We also document that the 27 February 2010 Mw 8.8 Maule, Chile earthquake triggered an exceptionally high rate of seismicity in the seconds to days following the main event. Although dormant, Uturuncu is currently being studied due to its large-scale deformation rate of 1-2 cm/yr uplift as revealed by InSAR. As part of the NASA-funded Andivolc project to investigate seismicity of volcanoes in the central Andes, a seismic network of 15 stations (9 Mark Products L22 short period and 6 Guralp CMG40T intermediate period sensors) with an average spacing of about 10 km was installed at Uturuncu from April 2009 to April 2010. Volcano-tectonic earthquakes occur at an average rate of about 3-4 per day, and swarms of 5-60 events within a span of minutes to hours occur a few times per month. Most of these earthquakes are located close to the summit at depths near and above sea level. The largest swarm occurred on 28 September 2009 and consisted of 60 locatable events over a time span of 28 hours. The locations of volcano-tectonic earthquakes at Uturuncu are oriented in a NW-SE trend, which matches the dominant orientation of regional faults and suggests a relationship between the fault system at Uturuncu and the regional tectonics of the area; a NW-SE trending fault beneath Uturuncu may serve to localize stresses that are accumulating over the broad area of uplift. Based on automated locations, the maximum local magnitude of these events is approximately M = 4 and the average magnitude is approximately M = 2. An initial estimate of the b-value is about b = 1.2. The Mw 8.8 Maule earthquake on 27 February 2010 triggered hundreds of local volcano-tectonic events at Uturuncu. High-pass filtering of the long period surface waves reveals that the first triggered events occurred with the onset of the Rayleigh

  18. Peculiar Active-Tectonic Landscape Within the Sanctuary of Zeus at Mt. Lykaion (Peloponnese, Greece)

    NASA Astrophysics Data System (ADS)

    Davis, G. H.

    2008-12-01

    The Sanctuary of Zeus (Mt. Lykaion) lies in the Peloponnese within the Pindos fold and thrust belt. It is the object of investigation of the Mt. Lykaion Excavation and Survey (http://lykaionexcavation.org/). Mt. Lykaion is a thrust klippe, on the summit of which is an upper sanctuary marked by an ash altar, temenos, and column bases. Earliest objects recovered from the ash altar go back to 3000 BCE, leading Dr. David Romano (University of Pennsylvania), a principal leader of the project, to conclude that worship of divinities on the summit is ancient. Detailed structural geological mapping reveals one dimension of the "power" of the site. Crisscrossing the upper sanctuary are scree bands that mark the traces of active normal faults, which are expressions of tectonic stretching of the Aegean region. The scree bands, composed of cinder-block-sized limestone blocks, range up to 10 m in outcrop breadth, 100 m in length, and 5 m in thickness. Though discontinuous, most of the scree bands lie precisely on the traces of through-going faults, which cut and displace the sedimentary formations of the Pindos group. Some cut the thrust fault, whose elliptical trace defines the Lykaion klippe. What makes the scree bands of this active-tectonic landscape "peculiar" is that there are no cliffs from which the scree descends. Rather, the bands of scree occur along flanks of smooth, rounded hillslopes and ridges. The scree bands coincide with modest steps in the topography, ranging from tens of centimeters to several tens of meters. The specific bedrock formation where the bands are best developed is an Upper Cretaceous limestone whose average platy-bedding thickness (approximately 20 cm) matches closely the average joint spacing. The limestone has little mechanical integrity. It cannot support itself as a scarp footwall and instead collapses into a pile of scree, whose upper-surface inclination conforms to a stable angle of repose. Evidence of the contemporary nature of this

  19. The Tectonic Event of the Cenozoic in the Tasman Area, Western Pacific, and Its Role in Eocene Global Change

    NASA Astrophysics Data System (ADS)

    Collot, J.; Sutherland, R.; Rouillard, P.; Patriat, M.; Roest, W. R.; Bache, F.

    2014-12-01

    . Together, these evidences form a tectonic event, which is manifest as a regional Eocene-Oligocene unconformity, and which is named the "Tectonic Event of the Cenozoic in the Tasman Area" (TECTA). Studying the absolute timing of TECTA and the relative timing of its sub-events will allow to better understand its role and relation to Eocene global change.

  20. Geochemistry of eclogite xenoliths in Mesozoic adakitic rocks from Xuzhou-Suzhou area in central China and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Xu, Wen-Liang; Gao, Shan; Yang, De-Bin; Pei, Fu-Ping; Wang, Qing-Hai

    2009-02-01

    Detailed geochemical (major and trace elements, Sr-Nd isotope) and new zircon U-Pb dating data for eclogite and garnet-clinopyroxenite xenoliths within the Mesozoic adakitic rocks from the Xuzhou-Suzhou area in central China provide insight into origin of their protolith and the Mesozoic tectonic evolution of the eastern North China Craton (NCC). The eclogite xenoliths have a basaltic bulk composition with SiO 2 = 44.44-52.30 wt.%, Al 2O 3 = 11.72-20.90 wt.%, FeO total = 7.35-17.28 wt.%, and MgO = 4.35-10.62 wt.%, CaO = 7.80-12.96 wt.%. They are characterized by enrichment in large ionic lithophile elements, depletion in high field strength elements (such as Nb, Ta, Zr, Hf, and Ti) and transitional elements (Ni and Cr), and variable Sr-Nd isotopic compositions (initial 87Sr/ 86Sr ratios and the ɛ Nd (t) values ranging from 0.7041 to 0.7139 and from 3.03 to - 17.19, respectively), suggesting that their protoliths could have been formed in an island arc setting. The zircon age spectrum suggests that the majority of the eclogite xenoliths have a NCC affinity and that few show characteristics of the Yangtze Craton (YC) basement. The existence of the YC basement beneath the NCC in the Xuzhou-Suzhou area, together with the discovery of the early Mesozoic metamorphic and Neoproterozoic magmatic inherited zircons in the Mesozoic granites from the eastern NCC, implies that the eclogite-facies metamorphism of the eastern NCC basement might be attributed to the early Mesozoic subduction of the YC beneath the NCC along the Tan-Lu fault zone oriented in a north-westward (NW) direction. The subsequent YC clockwise rotation with respect to the NCC, the large-scale lateral extrusion and uplift of the Tongbai-Dabie Mountains in eastern China after the Triassic collision, as well as the early Cretaceous strike-slip in the Tan-Lu fault zone, played the major role in formation of the present tectonic architecture of the Dabie-Sulu belts.

  1. Devonian-Carboniferous tectonics and basin deformation in the Cabot Strait Area, eastern Canada

    SciTech Connect

    Langdon, G.S.; Hall, J.

    1994-11-01

    The Magdalen Basin, in the Cabot Strait-Bay St. George area, was a major depocenter for Devonian-Carboniferous sediments in eastern Canada. Structure within the basin is complex and is characterized by northeast- and east-trending, mainly dextral strike-slip faults associated with the bend in the Appalachian orogenic belt known as the St. Lawrence Promontory. Under the Cabot Strait two linear grabens parallel the major fault trends and preserve up to 6 km of Devonian-Carboniferous sedimentary rocks, comprising mainly coarse-grained terrigenous clastics with a Lower Carboniferous transgressive episode recorded by marine carbonates, evaporites, and fine-grained clastics. Several unconformities within the sedimentary succession record deformation associated with movement along the regional strike-slip faults. Minor local unconformities are interpreted within the upper Horton (early Visean), upper Barachois (late Westphalian), and post-Pennsylvanian successions. A major unconformity cuts out most of the Namurian and Westphalian section in the study area and can be correlated on a regional scale. Kinematic strain partitioning along the master Cabot fault led to the development of doubly vergent compressional structures within a wrench borderland. This was complicated by transpressive deformation at a restraining bend in the master fault, and by deformation associated with over-stepped ends of splays of the regional fault system. The Magdalen Basin probably formed in an early phase of post-Acadian extension, and was later reactivated by regional strike-slip faults. The presence of thick source and reservoir rocks, as well as diverse trapping possibilities and a favorable burial and maturation history, indicate that the Cabot Strait area has good potential for accumulating and preserving petroleum.

  2. Radon concentration in soil gas around local disjunctive tectonic zones in the Krakow area.

    PubMed

    Swakoń, J; Kozak, K; Paszkowski, M; Gradziński, R; Łoskiewicz, J; Mazur, J; Janik, M; Bogacz, J; Horwacik, T; Olko, P

    2005-01-01

    The purpose of this study was to investigate radon in the vicinity of geologic fault zones within the Krakow region of Poland, and to determine the influence of such formations on enhanced radon concentrations in soil. Radon ((222)Rn and (220)Rn) concentration measurements in soil gas (using ionization chamber AlphaGUARD PQ2000 PRO and diffusion chambers with CR-39 detectors), as well as radioactive natural isotopes of radium, thorium and potassium in soil samples (using gamma ray spectrometry with NaI(Tl) and HPGe detectors), were performed. Site selection was based on a geological map of Krakow. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to recognize the geological structure of the area and to locate the predicted courses of faults. Elevated levels of radon and thoron in soil gas were found in the study area when compared with those observed in an earlier survey covering Krakow agglomeration. For (222)Rn, the arithmetic mean of registered concentration values was 39 kBq/m(3) (median: 35.5 kBq/m(3)). For (220)Rn, the arithmetic mean was 10.8 kBq/m(3) and median 11.8 kBq/m(3).

  3. Radon concentration in soil gas around local disjunctive tectonic zones in the Krakow area.

    PubMed

    Swakoń, J; Kozak, K; Paszkowski, M; Gradziński, R; Łoskiewicz, J; Mazur, J; Janik, M; Bogacz, J; Horwacik, T; Olko, P

    2005-01-01

    The purpose of this study was to investigate radon in the vicinity of geologic fault zones within the Krakow region of Poland, and to determine the influence of such formations on enhanced radon concentrations in soil. Radon ((222)Rn and (220)Rn) concentration measurements in soil gas (using ionization chamber AlphaGUARD PQ2000 PRO and diffusion chambers with CR-39 detectors), as well as radioactive natural isotopes of radium, thorium and potassium in soil samples (using gamma ray spectrometry with NaI(Tl) and HPGe detectors), were performed. Site selection was based on a geological map of Krakow. Geophysical methods (ground penetrating radar and shallow acoustic seismic) were applied to recognize the geological structure of the area and to locate the predicted courses of faults. Elevated levels of radon and thoron in soil gas were found in the study area when compared with those observed in an earlier survey covering Krakow agglomeration. For (222)Rn, the arithmetic mean of registered concentration values was 39 kBq/m(3) (median: 35.5 kBq/m(3)). For (220)Rn, the arithmetic mean was 10.8 kBq/m(3) and median 11.8 kBq/m(3). PMID:15511556

  4. Active tectonics of the Ganzi-Yushu fault in the southeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Shi, Feng; He, Honglin; Densmore, Alexander L.; Li, An; Yang, Xiaoping; Xu, Xiwei

    2016-04-01

    The ongoing convergence between India and Eurasia apparently is accommodated not merely by crustal shortening in Tibet, instead also by motions along strike slip faults which are usually boundaries between tectonic blocks, especially in the Tibetan Plateau. Quantification of this strike slip faulting is fundamental for understanding the collision between India and Eurasia. Here, we use a variety of geomorphic observations to place constraints on the late Quaternary kinematics and slip rates of the Ganzi-Yushu fault, one of the significant strike-slip faults in eastern Tibet. The Ganzi-Yushu fault is an active, dominantly left-lateral strike-slip structure that can be traced continuously for up to 500 km along the northern boundary of the clockwise-rotating southeastern block of the Tibetan Plateau. We analyse geomorphic evidence for deformation, and calculate the late Quaternary slip rates at four sites along the eastern portion of the fault trace. The latest Quaternary apparent throw rates are variable along strike but are typically ~ 1 mm/a. Rates of strike-slip displacement are likely to be an order of magnitude higher, 8-11 mm/a. Trenching at two locations suggests that the active fault behaviour is dominated by strike-slip faulting and reveals several earthquake events with refined information of timing. The 2010 Mw 6.9 Yushu earthquake, which occurred on the northwestern segment of the Ganzi-Yushu fault zone, provides additional evidence for fault activity. These observations agree with GPS-derived estimates, and show that late Quaternary slip rates on the Ganzi-Yushu fault are comparable to those on other major active strike-slip faults in the eastern Tibetan Plateau.

  5. Depths to the magnetic layer bottom in the South China Sea area and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Li, Chun-Feng; Shi, Xiaobin; Zhou, Zuyi; Li, Jiabiao; Geng, Jianhua; Chen, Bing

    2010-09-01

    The depths to the magnetic layer bottom (Zb) in the South China Sea (SCS) area are estimated by computing radially averaged amplitude spectra of total field magnetic anomalies. We test different sizes of moving windows in which the spectra are calculated to better understand how window sizes affect the depth estimations. Apart from lowering the resolutions of estimated Zb, larger windows do not necessarily incur presumable increases in Zb in the SCS area. Although the centroid method is taken as our primary technique for estimating Zb, for cross check, the spectral peak and the non-linear inversion methods are also applied to those windows where spectral peaks do appear. In a single window we may find discrepancy in Zb estimated from different techniques, but for all windows showing spectral peaks, the estimated Zb from one technique are grossly correlated with those from another. Our results show that most parts of the central SCS ocean basin and the northern continent-ocean transition (COT) zone have significantly smaller Zb than the surrounding continental blocks. In the surrounding continental regions Zb are averaged at about 34 km, a depth close to the Moho depth. The average Zb is about 22 km in the central basin, but this value is much larger than the Moho depth, signifying that the uppermost 10 km or so of the mantle beneath the central basin is also magnetized. The strong faulting and recent magmatism within the COT zone can account for the small Zb near the northern continental margin. The estimated Zb are also found very correlative to surface heat flow. This observation verifies dominant contributions to surface heat flow from incoming mantle heat flow due to thermal conduction. The positive correlations observed among Zb from different techniques as well as the good correlation between surface heat flow and Zb support the reasoning that our estimated Zb are within an acceptable range of accuracy.

  6. Analyzing the drainage system anomaly of Zagros basins: Implications for active tectonics

    NASA Astrophysics Data System (ADS)

    Bahrami, Shahram

    2013-11-01

    tectonic activities.

  7. Teleseismic P and S Delay Times within Tectonically Active and Stable North America

    NASA Astrophysics Data System (ADS)

    Lou, X.; van der Lee, S.

    2009-12-01

    We have measured teleseismic P and S relative delay times within 1) Stable North America (SNA) using waveforms from IRIS PASSCAL seismic arrays MOMA (Fischer et al., 1995), ABBA (Roecker and Beavan, 1995), Abitibi (Hearn and Mareschal, 1996), and FLED (Wysession and Fischer, 2001), and 2) Tectonically-active North America (TNA) using Earthscope's Transportable Array (TA). To study the contribution of mantle structure to these delays we subtracted delays predicted for topography and crustal structure, using CRUST 2.0 (Bassin et al., 2000). Preliminary analyses of delay times from earthquakes with Mw>=6.5 show surprising differences between the heterogeneity of the mantle beneath SNA and TNA. While the range of delay times is expectedly small for an intra-shield array such as Abitibi, the range of delay times from Proterozoic basement in the midwest to Paleozoic margin in New England is much larger and slightly exceeds that for the TA in TNA. This suggests that that the mantle of SNA is slightly more heterogeneous than TNA, despite there being relatively little surface expression of this heterogeneity. Patterns of P and S relative delay times measured in TNA correlate better with surface tectonics, suggesting that the mantle in TNA has a greater effect on the surface geology than in SNA. The central and southern Basin and Range are characterized by positive delays. As shown in previous studies, the Snake River Plain is also well delineated by positive delays. These delays exhibit a significant peak at station H17A in Yellowstone National Park. Teleseismic P and S waves arriving at stations in the Rocky Mountains are much faster, including in northern Idaho and western Washington, but not in western Oregon. For both SNA and TNA, the measured S and P delay times have a significant linear correlation, with S delays at approximately 3 times the P delays, which confirms the dominant effect of mantle temperature on mantle velocity structure. However, the slope of this

  8. Investigation of the geologic and tectonic structures of Bafa Lake and Akbuk Gulf (terrestrial and marine areas) by means of gravity and magnetic methods

    NASA Astrophysics Data System (ADS)

    Edremit, Şüheda; Özel, Erdeniz

    2016-04-01

    Geologic units of Bafa Lake and Akbuk Gulf, which have very importance in point of geologic and tectonic structure, are generally are classified by high-grade metamorphic units of the Menderes Core Complex, Cycladic Complex (schist, marble, eclogite), Afyon zone meta sedimentary and Pan-African basement rocks, Neogene volcanic-sedimentary rocks and alluvium. As for tectonic structures of study areas are; Izmir-Balikesir Transfer Zone also affected the Buyuk Menderes Graben, Bornova Flysch Zone, Menderes Massif and Lycian Nappes. Regional researches were studied to reveal using Turkey Bouguer Anomaly and Turkey Aeromagnetic regional map with gravity method used for geologic structures analysis and magnetic method used to explain main structure, tectonic conditions of underground. General geologic structure and tectonic lineaments of region were examined and interpretated compatibility with gravity and magnetic values. When the geologic and tectonic structures on the terrestrial areas are generally investigated, graben systems and linearities are clearly seen on the Bouguer Anomaly map. Positive values are seen in the Bornova Flysch Zone and Menderes Massif areas at the north of study areas arising from high-density ophiolitic and metamorphic units. Graben areas in the Menderes Massif are observed negative gravity values on the low-density young alluviums. Positive gravity values are increased up to 50-60 mgal on the metamorphic rocks that are named Cycladic Complex located southwest of study areas. At the aeromagnetic regional magnetic map, gamma values about -100 observed on the Menderes Massif region are indicated metagranite rocks that are Paleozoic crystalline structure. Gamma values, which are changed between -100 and +100 at the transition areas granite with schists, are obviously revealed this transition region. Located northwest of study areas Upper Miocene-Pliocene aged from sedimentary rocks on the terrestrial carbonates and nonsegregated terrestrial

  9. Active tectonics of northwestern U.S. inferred from GPS-derived surface velocities

    SciTech Connect

    Robert McCaffrey; Robert W. King; Suzette J. Payne; Matthew Lancaster

    2013-02-01

    Surface velocities derived from GPS observations from 1993 to 2011 at several hundred sites across the deforming northwestern United States are used to further elucidate the region's active tectonics. The new velocities reveal that the clockwise rotations, relative to North America, seen in Oregon and western Washington from earlier GPS observations, continue to the east to include the Snake River Plain of Idaho and south into the Basin and Range of northern Nevada. Regional-scale rotation is attributed to gravitationally driven extension in the Basin and Range and Pacific-North America shear transferred through the Walker Lane belt aided by potentially strong pinning below the Idaho Batholith. The large rotating section comprising eastern Oregon displays very low internal deformation rates despite seismological evidence for a thin crust, warm mantle, organized mantle flow, and elevated topography. The observed disparity between mantle and surface kinematics suggests that either little stress acts between them (low basal shear) or that the crust is strong relative to the mantle. The rotation of the Oregon block impinges on Washington across the Yakima fold-thrust belt where shortening occurs in a closing-fan style. Elastic fault locking at the Cascadia subduction zone is reevaluated using the GPS velocities and recently published uplift rates. The 18 year GPS and 80 year leveling data can both be matched with a common locking model suggesting that the locking has been stable over many decades. The rate of strain accumulation is consistent with hundreds of years between great subduction events.

  10. Analysis of the geological structure and tectonic evolution of Xingning-Jinghai sag in deep water area, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Han, Xiaoying; Ren, Jianye; Lin, Zi; Yang, Linlong

    2015-04-01

    Recent years, oil and gas exploration of the Pearl River Mouth Basin in the northern margin of South China Sea continuously achieved historic breakthroughs. The Xingning-Jinghai sag, which is located in southeast of the Pearl River Mouth Basin, is a deep-water sag with a great exploration potential. Its tectonic evolution is extremely complex. It experienced Mesozoic subduction to Cenozoic intra-continental rifting background, and finally evolved into a deep-water sag of the northern continental margin of South China Sea. The geological characteristics and the tectonic evolution of Xingning-Jinghai sag was closely related to the process of formation and evolution of the passive continental margin of the northern South China Sea. It is confirmed by many geophysical data that compared with adjacent Chaoshan depression, the crustal thickness of Xingning-Jinghai sag was rapidly thinning, and it developed detachment faults with later magmatic intrusion. The development of detachment faults have dynamic significance for the spreading of the South China Sea. Based on the seismic geological interpretation of 2D seismic data in the study area, the characteristics of detachment fault and supra-detachment basin have been proposed in this study. The characteristics of the detachment fault are low angle and high ratio between heave and throw. The geometry of the detachment fault is a typical lisric shape, with the dip of fault decreasing generally from the seismic profile. The detachment basin where sediments are not deposited over a tilting hanging-wall block but onto a tectonically exhumed footwall which is different from the typical half graben basin. Seismic profiles indicate two different structural styles in the east and west part of Xingning-Jinghai sag. In the west of the sag, there developed two large detachment faults, which control their detachment basin systems and the typical H block, and the two detachment faults are dipping landward and seaward, respectively. In

  11. Geochemistry and tectonic setting of the Central Loei volcanic rocks, Pak Chom area, Loei, northeastern Thailand

    NASA Astrophysics Data System (ADS)

    Panjasawatwong, Y.; Zaw, Khin; Chantaramee, S.; Limtrakun, P.; Pirarai, K.

    2006-01-01

    The Central Loei volcanic rocks, as evidenced by those in the Pak Chom area, were formed in the Late Devonian-Early Carboniferous and can be separated into three magmatic groups: transitional tholeiitic basalt, tholeiitic microgabbro and calc-alkalic basalt/andesite on the basis of immobile-element contents and ratios of least altered samples. All the tholeiitic microgabbro possibly occurred as dikes. Chemically, the transitional tholeittic basalt and tholeiitic microgabbro have higher abundances of TiO 2, Ni and Cr relative to the calc-alkalic basalt/andesite at similar values for FeO*/MgO; they also contain higher Ti/Zr but lower Zr/Nb. The transitional tholeiitic basalt has higher concentrations of P 2O 5 and Nb relative to the tholeiitic microgabbro at similar levels of FeO*/MgO, and also has higher ratios of Nb/Y and Ti/V, but lower values for Ti/Zr and Zr/Nb. In terms of chondrite normalized REE and N-MORB normalized patterns, the transitional tholeiitic basalt, tholeiitic basalt and calc-alkalic basalt/andesite are analogous to those from North Atlantic, Southwest Indian Ridge and New Britain Arc. On this basis, the Central Loei volcanic rocks are comprised of MORBs and oceanic island-arc lavas. These arc lavas may have erupted on an oceanic basement in the same ocean basin as those in the Chiang Rai-Chiang Mai volcanic belt.

  12. Integrated Geoscience Studies in the Greater Yellowstone Area - Volcanic, Tectonic, and Hydrothermal Processes in the Yellowstone Geoecosystem

    USGS Publications Warehouse

    Morgan, Lisa A.

    2007-01-01

    Yellowstone National Park, rimmed by a crescent of older mountainous terrain, has at its core the Quaternary Yellowstone Plateau, an undulating landscape shaped by forces of volcanism, tectonism, and later glaciation. Its spectacular hydrothermal systems cap this landscape. From 1997 through 2003, the United States Geological Survey Mineral Resources Program conducted a multidisciplinary project of Yellowstone National Park entitled Integrated Geoscience Studies of the Greater Yellowstone Area, building on a 130-year foundation of extensive field studies (including the Hayden survey of 1871, the Hague surveys of the 1880s through 1896, the studies of Iddings, Allen, and Day during the 1920s, and NASA-supported studies starting in the 1970s - now summarized in USGS Professional Paper 729 A through G) in this geologically dynamic terrain. The project applied a broad range of scientific disciplines and state-of-the-art technologies targeted to improve stewardship of the unique natural resources of Yellowstone and enable the National Park Service to effectively manage resources, protect park visitors from geologic hazards, and better educate the public on geologic processes and resources. This project combined a variety of data sets in characterizing the surficial and subsurface chemistry, mineralogy, geology, geophysics, and hydrothermal systems in various parts of the park. The sixteen chapters presented herein in USGS Professional Paper 1717, Integrated Geoscience Studies in the Greater Yellowstone Area - Volcanic, Tectonic, and Hydrothermal Processes in the Yellowstone Geoecosystem, can be divided into four major topical areas: (1) geologic studies, (2) Yellowstone Lake studies, (3) geochemical studies, and (4) geophysical studies. The geologic studies include a paper by Ken Pierce and others on the influence of the Yellowstone hotspot on landscape formation, the ecological effects of the hotspot, and the human experience and human geography of the greater

  13. Cretaceous and Paleogene granitoid suites of the Sikhote-Alin area (Far East Russia): Geochemistry and tectonic implications

    NASA Astrophysics Data System (ADS)

    Grebennikov, Andrei V.; Khanchuk, Alexander I.; Gonevchuk, Valeriy G.; Kovalenko, Sergey V.

    2016-09-01

    The Mesozoic and Cenozoic geological history of NE Asia comprises alternating episodes of subduction or transform strike-slip movement of the oceanic plate along the continental margin of Eurasia. This sequence resulted in the regular generation of granitoid suites that are characterized by different ages, compositions, and tectonic settings. The Hauterivian-Aptian orogenic stage of the Sikhote-Alin, associated with the strike-slip displacement of the early Paleozoic continental blocks, the successive deformation of the Jurassic and Early Cretaceous terranes, and the injection of the earliest S-type granitoids. During late Albian, the area underwent syn-strike-slip compression caused by collision with the Aptian island arc and resulted in the injection of voluminous magmas of calc-alkaline magnesian (S- and I-type) and alkali-calcic ferroan (A-type) granitoids into syn-faulting compressional and extensional basins, respectively. Northwestward to westward movement of the Izanagi Plate resulted in the initiation of frontal subduction of the Paleo-Pacific Plate during the Cenomanian-Maastrichtian. In turn, this resulted in the generation of plateau-forming ignimbrites and their intrusive analogs formed from metaluminous I-type felsic magmas. Paleocene-Eocene magmatism in the Sikhote-Alin area commenced after the termination of subduction in a rifting regime related to strike-slip movement of the oceanic plate relative to the continent. The break-off of the subducted plate and the injection of oceanic asthenospheric material into the subcontinental lithosphere resulted in the eruption of lamproites and fayalite rhyolites, and coeval intrusions of gabbro and alkali feldspar granites (А-type). The A-type granitic-rocks and coeval gabbro-monzonites are considered to be reliable indicators of the transform continental margin geodynamic settings.

  14. Cretaceous and Paleogene granitoid suites of the Sikhote-Alin area (Far East Russia): Geochemistry and tectonic implications

    NASA Astrophysics Data System (ADS)

    Grebennikov, Andrei V.; Khanchuk, Alexander I.; Gonevchuk, Valeriy G.; Kovalenko, Sergey V.

    2016-09-01

    The Mesozoic and Cenozoic geological history of NE Asia comprises alternating episodes of subduction or transform strike-slip movement of the oceanic plate along the continental margin of Eurasia. This sequence resulted in the regular generation of granitoid suites that are characterized by different ages, compositions, and tectonic settings. The Hauterivian-Aptian orogenic stage of the Sikhote-Alin, associated with the strike-slip displacement of the early Paleozoic continental blocks, the successive deformation of the Jurassic and Early Cretaceous terranes, and the injection of the earliest S-type granitoids. During late Albian, the area underwent syn-strike-slip compression caused by collision with the Aptian island arc and resulted in the injection of voluminous magmas of calc-alkaline magnesian (S- and I-type) and alkali-calcic ferroan (A-type) granitoids into syn-faulting compressional and extensional basins, respectively. Northwestward to westward movement of the Izanagi Plate resulted in the initiation of frontal subduction of the Paleo-Pacific Plate during the Cenomanian-Maastrichtian. In turn, this resulted in the generation of plateau-forming ignimbrites and their intrusive analogs formed from metaluminous I-type felsic magmas. Paleocene-Eocene magmatism in the Sikhote-Alin area commenced after the termination of subduction in a rifting regime related to strike-slip movement of the oceanic plate relative to the continent. The break-off of the subducted plate and the injection of oceanic asthenospheric material into the subcontinental lithosphere resulted in the eruption of lamproites and fayalite rhyolites, and coeval intrusions of gabbro and alkali feldspar granites (B-type). The A-type granitic-rocks and coeval gabbro-monzonites are considered to be reliable indicators of the transform continental margin geodynamic settings.

  15. A systematic overview of the coincidences of river sinuosity changes and tectonically active structures in the Pannonian Basin

    NASA Astrophysics Data System (ADS)

    Petrovszki, Judit; Székely, Balázs; Timár, Gábor

    2012-12-01

    As tectonic movements change the valley slope (low-gradient reaches of valleys, in sedimentary basins), the alluvial rivers, as sensitive indicators, respond to these changes, by varying their courses to accommodate this forcing. In our study sinuosity values, a commonly used characteristic parameter to detect river pattern changes, were studied for the major rivers in the Pannonian Basin in order to reveal neotectonic influence on their planform shape. Our study area comprises the entire Pannonian Basin (330,000 km2) located in eastern Central-Europe, bounded by the Alps, Carpathians and Dinarides. The studied rivers were mostly in their natural meandering state before the main river regulations of the 19th century. The last quasi-natural, non-regulated river planforms were surveyed somewhat earlier, during the Second Military Survey of the Habsburg Empire. Using the digitized river sections of that survey, the sinuosities of the rivers were calculated with different sample section sizes ranging from 5 km to 80 km. Depending on the bank-full discharge, also a 'most representative' section size is given, which can be connected to the neotectonic activity. In total, the meandering reaches of 28 rivers were studied; their combined length is 7406 km. The places where the river sinuosity changed were compared to the structural lines of the "Atlas of the present-day geodynamics of the Pannonian Basin" (Horváth et al., 2006). 36 junctions along 26 structural lines were identified where the fault lines of this neotectonic map crossed the rivers. Across these points the mean sinuosity changed. Depending on the direction of the relative vertical movements, the sinuosity values increased or decreased. There were some points, where the sinuosity changed in an opposite way. Along these sections, the rivers belong to the range of unorganized meandering or there are lithological margins. Assuming that the rivers indicate on-going faulting accurately, some places were found

  16. Analysis of Landsat TM data for active tectonics: the case of the Big Chino Fault, Arizona

    NASA Astrophysics Data System (ADS)

    Salvi, Stefano

    1994-12-01

    The Big Chino Valley is a 50 km-long tectonic depression of the Basin and Range province of the South- western United States. It is bordered on the NE side by an important normal fault, the Big Chino Fault. The activity of the latter has been hypothesised on the basis of the presence of a 20 m-high fault scarp and on local geomorphological studies. Moreover, a magnitude 4.9 earthquake occurred in southern Arizona in 1976 has been attributed to this fault. The climate in the Big Chino Valley is semi-arid with average rainfall of about 400 mm per year; a very sparse vegetation cover is present, yielding a good possibility for the geo-lithologic application of remote sensing data. The analysis of the TM spectral bands shows, in the short wave infrared, a clear variation in the reflected radiance across the fault scarp. Also the available radar (SLAR) images show a marked difference in response between the two sides of the fault. An explanation of this phenomena has been found in the interaction between the geomorphic evolution, the pedological composition, and the periodic occurrence of coseismic deformation along the fault. Other effects of the latter process have been investigated on colour D- stretched images whose interpretation allowed to detect two paleoseismic events of the Big Chino Fault. This work demonstrates that important information on the seismological parameters of active faults in arid and semiarid climates can be extracted from the analysis of satellite spectral data in the visible and near -infrared.

  17. Interactions between recent tectonic activity and the evolution of mountain relief of the Inner Cottians Alps (Western Alps): preliminary morphotectonic map.

    NASA Astrophysics Data System (ADS)

    Bacenetti, Marco; Morelli, Michele; Cadoppi, Paola; Giardino, Marco; Perotti, Luigi; Perrone, Gianluigi

    2014-05-01

    Possible interactions between recent tectonic activity and the evolution of mountain relief have been investigated at the regional (1:50,000) and local (1:5,000) scale in the Germanasca Valley (Cottian Alps, NW-Italy) through an integrated, multidisciplinary approach combining Structural analysis, Quaternary Geology, Geomorphology and Geomatics. The inner edge of the Cottians Alps and the adjacent Po Plain are among the most densely populated portions of the Piemonte Region (NW-Italy). This area corresponds to the junction between the Alpine and Apennine chains and it is affected by a diffuse low- to moderate- seismicity (Ml<5) and hypocenters at a shallow crustal level (< 20 Km). Available apatite fission track data indicate that this sector reached shallow crustal levels, where brittle deformation mechanisms prevail since Late Oligocene times. Historical earthquakes (e.g. Prarostino's earthquakes, 1808 Ml=5.5; Cumiana's earthquakes, 1980 Ml=4.8) caused both material and social damage in the area. Since faults activity is often associated with characteristic geomorphological features, linear valleys, ridgelines, slope-breaks, steep slopes of uniform aspect, regional anisotropy and tilt of terrain, have been detected in the area. Analysis of digital elevation models, by means of numerical geomorphology, provides a tool to recognize linear features and characterizing the tectonics of an area in a quantitative way. Geomorphology and morphotectonic analyses have been performed using digital orthophotos (AGEA Orthophoto 2009), aerial stereo couples and DEMs (LiDAR5x5 meters, Regione Piemonte 2009). The morphotectonic lineament analysis was conducted using TerraExplorer® Software Systems, Inc. For the field mapping activities, it was used an application called "SRG2" (Support to Geological / Geomorphological Surveys), an extension for ArcPad (ESRI mobile GIS). Into ArcPad, the SRG2 application adds a toolbar made up of several functions for a useful mapping and

  18. Late Paleozoic magmatic record of Middle Gobi area, South Mongolia and its implications for tectonic evolution: Evidences from zircon U-Pb dating and geochemistry

    NASA Astrophysics Data System (ADS)

    Zhu, Mingshuai; Miao, Laicheng; Baatar, Munkhtsengel; Zhang, Fochin; Anaad, Chimedtseren; Yang, Shunhu; Li, Xingbo

    2016-01-01

    Late Paleozoic subduction-accretion complexes occur widely in Middle Gobi area and provide a good opportunity for unraveling the Paleozoic tectonic evolution of South Mongolia. The magmatic rocks in the Tsavchir hudug district mainly consist of rhyolites and volcaniclastic rocks. The rhyolites show enrichment in LREE and LILE and negative Nb, Ta and Ti anomalies, indicating genesis in the subduction zone. A rhyolite sample from the Tsavchir hudug region yielded a SHRIMP 206Pb/238U zircon age of 315 ± 4 Ma (MSWD = 0.79, n = 15). The andesite overlying the Namdain hundy Early Paleozoic ophiolite shows adakite geochemical features, and the two andesite samples yielded SHRIMP 206Pb/238U zircon ages of 325 ± 3 Ma (MSWD = 1.6, n = 14) and 319 ± 4 Ma (MSWD = 0.56, n = 13), respectively, suggesting that the Carboniferous island arc formed on the basis of Early Paleozoic accretionary complex. The granodiorite sample that intrudes the Early Paleozoic accretion complex with adakite geochemical features yielded a SHRIMP 206Pb/238U zircon age of 333 ± 4 Ma (MSWD = 1.6, n = 16), representing the Late Paleozoic island arc intrusive. The SHRIMP U-Pb analyses for the tuff sandstones that occur associated with Early Paleozic oceanic inliers in Middle Gobi area suggest detrital zircons mainly stem from the Devonian-Carboniferous arc. The age data obtained from the ophiolite (528-509 Ma) and tuff sandstone indicate the accretion in Middle Gobi area lasted from Early Paleozoic to Late Paleozoic for at least ca. 200 Ma, suggesting the ocean of the accretionary complex was the major Paleo-Asain ocean basin. The subduction related magmatic belt in Middle Gobi area includes both Early Paleozoic and Late Paleozoic island arc activities, which is consistent with the accretion duration time obtained from accretionary complex and also attests the argument of major Paleo-Asain ocean basin.

  19. Geology is the Key to Explain Igneous Activity in the Mediterranean Area

    NASA Astrophysics Data System (ADS)

    Lustrino, M.

    2014-12-01

    Igneous activity in tectonically complex areas can be interpreted in many different ways, producing completely different petrogenetic models. Processes such as oceanic and continental subduction, lithospheric delamination, changes in subduction polarity, slab break-off and mantle plumes have all been advocated as causes for changes in plate boundaries and magma production, including rate and temporal distribution, in the circum-Mediterranean area. This region thus provides a natural laboratory to investigate a range of geodynamic and magmatic processes. Although many petrologic and tectonic models have been proposed, a number of highly controversial questions still remain. No consensus has yet been reached about the capacity of plate-tectonic processes to explain the origin and style of the magmatism. Similarly, there is still not consensus on the ability of geochemical and petrological arguments to reveal the geodynamic evolution of the area. The wide range of chemical and mineralogical magma compositions produced within and around the Mediterranean, from carbonatites to strongly silica-undersaturated silico-carbonatites and melilitites to strongly silica-oversaturated rhyolites, complicate models and usually require a large number of unconstrained assumptions. Can the calcalkaline-sodic alkaline transition be related to any common petrogenetic point? Is igneous activity plate-tectonic- (top-down) or deep-mantle-controlled (bottom-up)? Do the rare carbonatites and carbonate-rich igneous rocks derive from the deep mantle or a normal, CO2-bearing upper mantle? Do ultrapotassic compositions require continental subduction? Understanding chemically complex magmas emplaced in tectonically complex areas require open minds, and avoiding dogma and assumptions. Studying the geology and shallow dynamics, not speculating about the deep lower mantle, is the key to understanding the igneous activity.

  20. Tectonic Plate Movement.

    ERIC Educational Resources Information Center

    Landalf, Helen

    1998-01-01

    Presents an activity that employs movement to enable students to understand concepts related to plate tectonics. Argues that movement brings topics to life in a concrete way and helps children retain knowledge. (DDR)

  1. Earthquakes and plate tectonics.

    USGS Publications Warehouse

    Spall, H.

    1982-01-01

    Earthquakes occur at the following three kinds of plate boundary: ocean ridges where the plates are pulled apart, margins where the plates scrape past one another, and margins where one plate is thrust under the other. Thus, we can predict the general regions on the earth's surface where we can expect large earthquakes in the future. We know that each year about 140 earthquakes of magnitude 6 or greater will occur within this area which is 10% of the earth's surface. But on a worldwide basis we cannot say with much accuracy when these events will occur. The reason is that the processes in plate tectonics have been going on for millions of years. Averaged over this interval, plate motions amount to several mm per year. But at any instant in geologic time, for example the year 1982, we do not know, exactly where we are in the worldwide cycle of strain build-up and strain release. Only by monitoring the stress and strain in small areas, for instance, the San Andreas fault, in great detail can we hope to predict when renewed activity in that part of the plate tectonics arena is likely to take place. -from Author

  2. Tectonics and Quaternary sequence development of basins along the active Vienna Basin strike-slip fault

    NASA Astrophysics Data System (ADS)

    Salcher, B.; Lomax, J.; Meurers, B.; Smit, J.; Preusser, F.; Decker, K.

    2012-04-01

    The Vienna Basin strike-slip fault is a continent scale active fault extending over a distance of some 300 km from the Eastern Alps through the Vienna Basin into the Western Carpathians. Sinistral movement causes the formation of several tight Pleistocene strike-slip basins within the older Miocene Vienna Basin. These sub-basins not only have a high relevance for groundwater exploitation but their fault activities depict serious seismic hazards. Basins are filled with fluvial sediments from the Danube and, closer to the Alpine front, with thick alluvial fan deposits. However, knowledge on the stratigraphy and tectonics is sparse and rather limited to the Miocene part of the Vienna Basin as it hosts giant hydrocarbon fields. This study tackles two major questions: (i) What is the effect of Quaternary climatic oscillations and subsidence on the sequence development of the alluvial fans and (ii) what is the deformation style of these basins? To answer (i) we present a series of new OSL ages and biotic data from both, surface and cores, to better constrain the timing of fan activity, fan abandonment but also to constrain the onset of Pleistocene basin formation. For (ii) we utilize information from unparalleled geophysical and geological data. Specifically we utilize industrial Bouguer gravity's derivatives to highlight shallow structures and to compensate for the lag of fault trace information. The integration of geological and geophysical data highlights textbook-like models of strike-slip basins, with typical features like Riedel shears with intervening relay ramps, en-echelon sidewall faults and a cross-basin fault zone delimiting opposite depocenters. The infill reflects a distinct cyclicity with thick sequences of coarse sediments deposited during colder periods and thin sequences of paleosol and flood sediments deposited during warmer periods. Ages indicate main activity around the short peak glacial periods and basin formation starting c. 300 ka ago. The

  3. Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

    USGS Publications Warehouse

    Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Campbell, Kenneth; Abrahamson, Norman; Silva, Walter

    2012-01-01

    Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.

  4. Extensional geometries as a result of regional scale thrusting: tectonic slides of the Dunlewy-NW Donegal area, Ireland

    NASA Astrophysics Data System (ADS)

    Hutton, Donald H. W.; Alsop, G. Ian

    1995-09-01

    The synmetamorphic ductile dislocations, known in the British Caledonian literature as 'Tectonic Slides', pose a classical structural problem. That is, despite being associated with synchronous contractional folds and cleavages the low angle dislocations have the effect, in many celebrated cases, of juxtaposing younger over older rocks: a geometry normally associated with extensional rather than contractional deformation. Recent models have attempted to demonstrate that this is the result of thrust reactivation of original, sedimentary, extensional growth faults. The Appin Group Dalradian metasediments of the complex and small Dunlewy area of NW Donegal, Ireland, contain the following geometric elements: (a) an early strike-swing-related stratigraphic facies change; (b) a major inter-deformational dolerite sheet; (c) major regional recumbent folds and slides; (d) major structures related to the 400 Ma sinistral Main Donegal Granite shear zone. This solution to the structural geometry reveals that the early mid-crustal (~11 km depth) D2 Ardsbeg-Dunlewy Slide is a thrust to the northwest. Its hangingwall contains rocks two-thirds of which are younger than the rocks of the footwall, together with major recumbent folds, coeval with the underlying thrust, which face downwards into the thrust in the direction of transport. Rather than thrust reactivation of an original extensional growth fault, we find that both stratigraphic and structural constraints are satisfied by a double thrusting model, with fault-bend folding onto an upper ramp of an earlier formed but penecontemporaneous and kinematically linked major fold pair. This solution to the geology also allows us to recognize that the regional (pre-granite) structure of the Dalradian of NW Donegal is a series of major D2 synmetamorphic thrust bounded nappes possibly involving up to 250 km of northwesterly overthrusting.

  5. Moment tensor inversion of recent local moderate sized Van Earthquakes: seismicity and active tectonics of the Van region : Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Kalafat, D.; Suvarikli, M.; Ogutcu, Z.; Kekovali, K.; Ocal, M. F.; Gunes, Y.; Pinar, A.

    2013-12-01

    The study area of the present research, the Van Region is located at the norththern end of the collision zone between the Anatolia and Arabian plates. Therefore, the southeast border of the Anatolian plate collides with the Arabian plate along the Bitlis Suture Zone. This zone is formed by collision of Arabian and in large scale Eurasian plates at mid-Miocen age. This type of thrust generation as a result of compressional regime extends east-west. The largest recorded earthquakes have all taken place along Southern Turkey (e.g. Lice, 1971; Varto, 1966; Caldiran, 1976). On the 23th of October 2011, an earthquake shook the Van Lake, Eastern Turkey, following a seismic sequence of more than three months in an unprecedented episode for this region characterized by null or low seismicity. The October 23, 2011 Van-Ercis Earthquake (Mw=7.1) was the most devastating resulting in loss of life and destruction. In order to study the aftershocks' activity of this main event, we installed and kept a seismic network of 10 broad-band (BB) stations in the area for an interval of nearly fifteen months. We characterized the seismogenic structure of the zone by calculating a minimum 1-D local velocity model and obtaining precise hypocentre locations. We also calculated fault plane solutions for more than 200 moderate sized earthquakes based on first motion polarities and commonly Moment Tensor Inversion Methods. The seismogenic zone would be localized at aproximately 10 km depth. Generally, the distribution of the important moderate earthquakes and the aftershock distribution shows that the E-W and NE-SW oriented fault segments cause the earthquake activities. Aftershock events are located along the eastern border of Lake Van and mainly between 5 and 10 km depth and disposed in two alignments: a ~E-W-trending alignment that matches with the trace of the Van Trust fault Zone and a NE-trending which could correspond to an structure not previously seen. Selected focal mechanisms show a

  6. Identification and interpretation of tectonic features from ERTS-1 imagery: Southwestern North America and the Red Sea area

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator); Tubbesing, L.

    1975-01-01

    The author has identified the following significant results. The ERTS-1 imagery was utilized to study major fault and tectonic lines and their intersections in southwestern North America. A system of transverse shear faults was recognized in the California Coast Ranges, the Sierra Nevada, the Great Basin, and Mexico. They are interpreted as expressions of a major left-lateral shear which predated the San Andreas system, the opening of the Gulf of California and Basin and Range rift development. Tectonic models for Basin and Range, Coast Ranges, and Texas-Parras shears were developed. Geological structures and Precambrian metamorphic trend lines of schistosity were studied across the Red Sea rift.

  7. Tectonic Geomorphology.

    ERIC Educational Resources Information Center

    Bull, William B.

    1984-01-01

    Summarizes representative quantitative tectonic-geomorphology studies made during the last century, focusing on fault-bounded mountain-front escarpments, marine terraces, and alluvial geomorphic surfaces (considering stream terraces, piedmont fault scarps, and soils chronosequences). Also suggests where tectonic-geomorphology courses may best fit…

  8. Coupling Fluvial Processes and Landslide Distribution Toward Geomorphological Hazard Assessment: Cases in Tectonically Active Mountain Ranges in Taiwan and Japan

    NASA Astrophysics Data System (ADS)

    Tsou, C. Y.; Chigira, M.; Matsushi, Y.; Arai, N.; Chen, S. C.; Feng, Z. Y.

    2015-12-01

    Large-scale destabilization of mountain slopes, which are affected by long-term river incision, give rise to the risk of catastrophic failures in tectonically active ranges. We found deep-seated gravitational slope deformations (DGSDs) induced by these processes in the Chishan River and Dahan River in the Central Range in Taiwan and the Kumano River in the Kii Mts. in Japan. These areas comprise paleosurface remnants with moderate relief at higher elevations and incised V-shaped inner gorges below them, which were made by the recession of knickpoints. Our studies include field surveys, mapping of DGSD and landslide scars, and cosmogenic nuclide exposure dating of several landform surfaces. In the Dahan River catchment, rims of paleosurfaces, which have a minimum age of ca. 150 kyr, are distributed up to 600 m above the present river bed, acting as a proxy of fluvial dissection associated with phases of river incision since the middle to late Pleistocene. The relationships between slope movements and the topography modified by the river incision show that about 53% of all DGSDs, or all large DGSDs (>106 m2) and catastrophic landslides occurred on slopes along the rims of paleosurfaces, suggesting they could be fundamentally controlled by long-term river incision. Catastrophic landslides observed along or below the rims of paleosurfaces were preceded by buckling of alternating beds of sandstone and mudstone on parallel or underdip cataclinal slopes dipped at 50° to 58°. This suggests that the peripheral zones of the paleosurfaces may be most susceptible to future catastrophic landslides, particularly on parallel or underdip cataclinal slopes comprising alternating beds of sandstone and mudstone dipping at 50° to 60°. The 2009 Typhoon Morakot-induced Shiaolin landslide along the Chishan River and the 2011 Typhoon Talas-induced catastrophic landslides along the Kumano River also occurred on the gravitationally deformed slopes along the rims of paleosurfaces.

  9. Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

    NASA Astrophysics Data System (ADS)

    Eisses, A.; Kell, A. M.; Kent, G.; Driscoll, N. W.; Karlin, R. E.; Baskin, R. L.; Louie, J. N.; Smith, K. D.; Pullammanappallil, S.

    2011-12-01

    Preliminary slip rates measured across the East Pyramid Lake fault, or the Lake Range fault, help provide new estimates of extension across the Pyramid Lake basin. Multiple stratigraphic horizons spanning 48 ka were tracked throughout the lake, with layer offsets measured across all significant faults in the basin. A chronstratigraphic framework acquired from four sediment cores allows slip rates of the Lake Range and other faults to be calculated accurately. This region of the northern Walker Lake, strategically placed between the right-lateral strike-slip faults of Honey and Eagle Lakes to the north, and the normal fault bounded basins to the southwest (e.g., Tahoe, Carson), is critical in understanding the underlying structural complexity that is not only necessary for geothermal exploration, but also earthquake hazard assessment due to the proximity of the Reno-Sparks metropolitan area. In addition, our seismic CHIRP imaging with submeter resolution allows the construction of the first fault map of Pyramid Lake. The Lake Range fault can be obviously traced west of Anahoe Island extending north along the east end of the lake in numerous CHIRP lines. Initial drafts of the fault map reveal active transtension through a series of numerous, small, northwest striking, oblique-slip faults in the north end of the lake. A previously field mapped northwest striking fault near Sutcliff can be extended into the west end of Pyramid Lake. This fault map, along with the calculated slip rate of the Lake Range, and potentially multiple other faults, gives a clearer picture into understanding the geothermal potential, tectonic regime and earthquake hazards in the Pyramid Lake basin and the northern Walker Lane. These new results have also been merged with seismicity maps, along with focal mechanisms for the larger events to begin to extend our fault map in depth.

  10. Tectonic setting of the Portland-Vancouver area, Oregon and Washington: constraints from low-altitude aeromagnetic data

    USGS Publications Warehouse

    Blakely, R.J.; Wells, R.E.; Yelin, T.S.; Madin, I.P.; Beeson, M.H.

    1995-01-01

    Seismic activity in the Portland-Vancouver metropolitan area may be associated with various mapped faults that locally offset volcanic basement of Eocene age and younger. This volcanic basement is concealed in most places by young deposits, vegetation, and urban development. The US Geological Survey conducted an aeromagnetic survey in September 1992 to investigate the extent of these mapped faults and possibly to help identify other seismic and volcanic hazards in the area. The survey was flown approximately 240 m above terrain, along flight lines spaced 460 m apart, and over an area about 50 ?? 50 km. -from Authors

  11. Facility Focus: Student Activity Areas.

    ERIC Educational Resources Information Center

    College Planning & Management, 2001

    2001-01-01

    Discusses the design of student activity facilities that are showpieces containing both business and entertainment elements. Four examples are highlighted including a performing arts center, a college gym, a student services facility, and a student union. (GR)

  12. Lake Clark fault, assessment of tectonic activity based on reconnaissance mapping of glacial deposits, northwestern Cook Inlet Alaska

    NASA Astrophysics Data System (ADS)

    Reger, R. D.; Koehler, R. D.

    2009-12-01

    The Lake Clark fault extends ~247 km from the vicinity of Lake Clark in the Alaska-Aleutian Range batholith northeastward to the Castle Mountain fault along the northern margin of Cook Inlet. Documented Tertiary deformation along the fault includes dextral offsets (5-26 km) and north-side-up reverse displacements (500-1,000 m). The fault is along strike with the Holocene-active Castle Mountain fault and adjacent to the active northern Cook Inlet fold belt. As part of the STATEMAP program, the State of Alaska has begun a 2-year geologic mapping project in the vicinity of the Lake Clark fault, including assessment of Quaternary fault activity and its role in accommodating deformation in the Aleutian forearc. Here we present preliminary Quaternary mapping and tectonic geomorphic observations aimed at assessing the fault activity. Between the Beluga and Chakachatna rivers, large lateral moraines of the late Wisconsinan Naptowne glaciation cross the fault and are not displaced. In the vicinity of Lone Ridge, the fault is expressed as a ~25-m southeast-facing scarp in bedrock associated with springs and vertically offset Stage 4 or 6 moraines. In the Chuitna River drainage basin beyond the Naptowne ice limit, the fault extends across a fairly flat plateau with drumlins and ice-stagnation deposits related to Stage 4 or 6 glaciation. There the fault is expressed by subtle vegetation and tonal lineaments on air photos; however, scarps and lateral offsets were not observed. Stream profiles perpendicular to the fault along the Chuitna River and Chuitna Creek have convex profiles that could be related to tectonic folding. Our observations indicate that this part of the Lake Clark fault may be Quaternary active, but has been relatively quiescent in the late Pleistocene. Thus, blind thrust faults associated with the northern Cook Inlet fold belt may accommodate the majority of the tectonic deformation in this part of the Aleutian forearc. This information is applicable to

  13. Tank Focus Area pretreatment activities

    SciTech Connect

    McGinnis, C.P.; Welch, T.D.; Manke, K.L.

    1997-03-01

    Plans call for the high-level wastes to be retrieved from the tanks and immobilized in a stable waste form suitable for long-term isolation. Chemistry and chemical engineering operations are required to retrieve the wastes, to condition the wastes for subsequent steps, and to reduce the costs of the waste management enterprise. Pretreatment includes those processes between retrieval and immobilization, and includes preparation of suitable feed material for immobilization and separations to partition the waste into streams that yield lower life-cycle costs. Some of the technologies being developed by the Tank Focus Area (TFA) to process these wastes are described. These technologies fall roughly into three areas: (1) solid/liquid separation (SLS), (2) sludge pretreatment, and (3) supernate pretreatment.

  14. Tectonic Geomorphology of an Active Low-Angle Normal Fault, Sierra El Mayor, Northern Baja California

    NASA Astrophysics Data System (ADS)

    Fletcher, J. M.; Spelz, R.

    2007-05-01

    Low angle normal faults (LANF) are ubiquitously distributed throughout the northern Gulf of California. They commonly bound uplifted mountain ranges and are found in numerous seismic sections in the Altar Desert and Wagner Basin (A. Martin, unpublished data). The Canada David detachment (CDD) is a spectacular example of an active LANF that controls the western mountain front of Sierra El Mayor over a strike length of 60 Km. Like most LANFs, the CDD contains two prominent antiform-synform megamullion pairs that strongly control the tectonic geomorphology of the uplifted footwall block and alluvial terraces along the range flank. Quantitative morphometric analysis along the mountain front shows that drainage basins in antiformal domains have systematically higher outlet elevations, higher gradients, greater relief, and much greater hypsometric integrals. Additionally river valleys are narrower and dominated by bedrock channels that extend nearly to the outlet, which is consistent with the fact that mountain front sinuosity is almost an order of magnitude less in the antiformal domains. A sequence of as many as 8 different regional strath terraces are preserved along the range flank and reconnaissance dating of the deposits by cosmogenic isotopes suggests that they formed during the major interglacial-to-glacial climatic transitions. Strath terraces are generally much older, and relative heights between terraces is significantly lower in synformal domains. All of these geomorphologic characteristics suggest that the synformal domains have experienced much lower rates of uplift and erosion of the footwall and likewise lower rates of sedimentation in the adjacent hanging wall basin. The lack of slip gradients on the master fault between synformal and antiformal domains suggests that the megamullions formed instead by regional buckling perpendicular to the extension direction. A Quaternary scarp array extends along the entire length of the mountain front and also shows

  15. Normal faulting along the western side of the Matese Mountains: Implications for active tectonics in the Central Apennines (Italy)

    NASA Astrophysics Data System (ADS)

    Boncio, Paolo; Dichiarante, Anna Maria; Auciello, Eugenio; Saroli, Michele; Stoppa, Francesco

    2016-01-01

    We provide new field data from geologic mapping and bedrock structural geology along the western side of the Matese Mts in central Italy, a region of high seismicity, strain rates among the highest of the entire Apennines (4-5 mm/yr GPS-determined extension), and poorly constrained active faults. The existing knowledge on the Aquae Iuliae normal fault (AIF) was implemented with geometric and kinematic data that better constrain its total length (16.5 km), the minimum long-term throw rate (0.3-0.4 mm/yr, post-late glacial maximum, LGM), and the segmentation. For the first time, we provide evidence of post-350 ka and possibly late Quaternary activity of the Ailano - Piedimonte Matese normal fault (APMF). The APMF is 18 km long. It is composed of a main 11 km-long segment striking NW-SE and progressively bending to the E-W in its southern part, and a 7 km-long segment striking E-W to ENE-WSW with very poor evidence of recent activity. The available data suggest a possible post-LGM throw rate of the main segment of ≳0.15 mm/yr. There is no evidence of active linkage in the step-over zone between the AIF and APMF (Prata Sannita step-over). An original tectonic model is proposed by comparing structural and geodetic data. The AIF and APMF belong to two major, nearly parallel fault systems. One system runs at the core of the Matese Mts and is formed by the AIF and the faults of the Gallo-Letino-Matese Lake system. The other system runs along the western side of the Matese Mts and is formed by the APMF, linked to the SE with the Piedimonte Matese - Gioia Sannitica fault. The finite extension of the APMF might be transferred to the NW towards the San Pietro Infine fault. The nearly 2-3 mm/yr GPS-determined extension rate is probably partitioned between the two systems, with a ratio that is difficult to establish due to poor GPS coverage. The proposed model, though incomplete (several faults/transfer zones need further investigations), aids in the seismotectonic

  16. Fault kinematics and tectonic stress in the seismically active Manyara Dodoma Rift segment in Central Tanzania Implications for the East African Rift

    NASA Astrophysics Data System (ADS)

    Macheyeki, Athanas S.; Delvaux, Damien; De Batist, Marc; Mruma, Abdulkarim

    2008-07-01

    The Eastern Branch of the East African Rift System is well known in Ethiopia (Main Ethiopian Rift) and Kenya (Kenya or Gregory Rift) and is usually considered to fade away southwards in the North Tanzanian Divergence, where it splits into the Eyasi, Manyara and Pangani segments. Further towards the south, rift structures are more weakly expressed and this area has not attracted much attention since the mapping and exploratory works of the 1950s. In November 4, 2002, an earthquake of magnitude Mb = 5.5 struck Dodoma, the capital city of Tanzania. Analysis of modern digital relief, seismological and geological data reveals that ongoing tectonic deformation is presently affecting a broad N-S trending belt, extending southward from the North Tanzanian Divergence to the region of Dodoma, forming the proposed "Manyara-Dodoma Rift segment". North of Arusha-Ngorongoro line, the rift is confined to a narrow belt (Natron graben in Tanzania) and south of it, it broadens into a wide deformation zone which includes both the Eyasi and Manyara grabens. The two-stage rifting model proposed for Kenya and North Tanzania also applies to the Manyara-Dodoma Rift segment. In a first stage, large, well-expressed topographic and volcanogenic structures were initiated in the Natron, Eyasi and Manyara grabens during the Late Miocene to Pliocene. From the Middle Pleistocene onwards, deformations related to the second rifting stage propagated southwards to the Dodoma region. These young structures have still limited morphological expressions compared to the structures formed during the first stage. However, they appear to be tectonically active as shown by the high concentration of moderate earthquakes into earthquake swarms, the distribution of He-bearing thermal springs, the morphological freshness of the fault scarps, and the presence of open surface fractures. Fault kinematic and paleostress analysis of geological fault data in basement rocks along the active fault lines show that recent

  17. Kinematic Evolution of fold-and-thrust Belts in the Yubei Area: Implications for the Tectonic Events of Ordovician at the Southern Tarim Basin

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2015-12-01

    As a response to tecto-orogenic processes of the South Altun and the West Kunlun (Monlar P, 1975; He Bizhu, 2011), early Paleozoic tectonic evolution of the southern Tarim craton was distinctively one of the extensions and was followed by compression (Morris W.Leighton, 1990; Gao Zhiqian, 2015). From the late Ordovician, the Yubei area developed distinctively NE-SW trending fold-and-thrust belts in rows which were eroded and deformed through multiphase tectonic movement (Dengfa He, 2007), with similarities and dissimilarities between each other rows in many aspects, at the Southern Tarim inner basin (Fig. 1). The northern of Hetian paleo-uplift and the northwestern of NE-trending folds zone on Caledonian in Tangguzibasi depression should be favorable to the potential exploration area for the first large-scale period of hydrocarbon migration and accumulation (Brown LF, 1979). In this contribution, based on geophysical log, core and 2D/3D seismic data, we constructed its tectonic geometry morphology, controlled by detailed chronostratigraphic framework. According to the fault-related fold theory, rows of asymmetric fault-propagation folds grew in the Yubei area during the late Caledonian period, with the evidence of interpreted growth strata from the high resolution 3D seismic data (Suppe J et al., 1990). That intercontinental tecto-orogenic events from southern Tarim basin, leading to the transformation of its margins, affected inner basin at that time, modified the basin into the Tarim metacraton (Jean-Paul Liégeois, 2013; Zieglar P.A., 1998). Correlating the four tectonic groups of the identified with the axis variation of strata and fold amplitude distribution showed that fault evolution progressed in several superimposed stages: Precambrian, late Ordovician to early Carboniferous (Zhao Zongju, 2009), Carboniferous to Permian, Cenozoic. Analyzing the sedimentary development and structure evolution the tectonic paleo-geographic setting is reconstructed, providing

  18. The Physics of a Volcanic System: What is the Actual Role Played by Tectonic Setting in Controlling Volcanic Activity?

    NASA Astrophysics Data System (ADS)

    Canon-Tapia, E.

    2005-12-01

    Modern text-books commonly explain volcanic activity as a direct consequence of plate tectonics, overlooking the different scales characteristic of both types of processes. By acknowledging such differences, however, it is possible to envisage a model of a volcanic system that is based in the same principles of hydrostatics established by Blaise Pascal over 300 yrs ago. Such principles allow us to estimate the local conditions required for the occurrence of volcanism at a given location highlighting the importance of the rock strength and the density difference between melt and its surroundings. This model shows that the minimum thickness of the zone of partial melting in the mantle (or seismically defined Low Velocity Zone) that is required to feed volcanic activity might range from 5 to over 100 km, but also that under certain circumstances a rock strength < 200 MPa may suffice to keep magma trapped at depth whereas in other cases a strength > 600 MPa will not suffice to stop magma ascent resulting in volcanic activity at the surface. Consequently, the model of volcanism developed here explains why is that a given LVZ may lead to volcanic activity in some places whereas a completely identical LVZ may not result in volcanic activity in a different location. Consequently, this model provides a general framework that allows us to better understand the actual role played by tectonic setting in controlling volcanism at a planetary scale.

  19. Active tectonics, paleoseismology and associated methodological challenges posed by the slow moving Alhama de Murcia fault (SE Iberia)

    NASA Astrophysics Data System (ADS)

    Ferrater, Marta; Ortuño, Maria; Masana, Eulàlia; Pallàs, Raimon; Perea, Hector; Baize, Stephane; García-Meléndez, Eduardo; Martínez-Díaz, José J.; Echeverria, Anna; Rockwell, Thomas; Sharp, Warren D.; Arrowsmith, Ramon; Medialdea, Alicia; Rhodes, Edward

    2016-04-01

    The Alhama de Murcia fault (AMF) is a 87 km-long left-lateral slow moving fault and is responsible for the 5.1 Mw 2011 Lorca earthquake. The characterization of the seismic potential of seismogenic strike-slip slow moving faults is necessary but raises huge methodological challenges, as most paleoseismological and active tectonic techniques have been designed on and for fast moving faults. The AMF is used here as a pilot study area to adapt the traditional geomorphological and trenching analyses, especially concerning the precise quantification of offset channels. We: 1) adapted methodologies to slow moving faults, 2) obtained, for the first time, the slip rate of the AMF, and 3) updated its recurrence period and maximum expected magnitude. Morphotectonic studies aim to use the measured tectonic offset of surface channels to calculate seismic parameters. However, these studies lack a standard criterion to score the analysed features. We improved this by differentiating between subjective and objective qualities, and determining up to three objective parameters (lithological changes, associated morphotectonics and shape, and three shape sub-parameters; all ranging from 0 to 1). By applying this methodology to the AMF, we identified and characterized 138 offset features that we mapped on a high-resolution (0.5 × 0.5 m pixel size) Digital Elevation Model (DEM) from a point cloud acquired in 2013 by airborne light detection and ranging (lidar). The identified offsets, together with the ongoing datings, are going to be used to calculate the lateral slip rate of the AMF. In three-dimensional trenches, we measured the offsets of a buried channel by projecting the far-field tendency of the channel onto the fault. This procedure is inspired by the widespread geomorphological procedure and aims to avoid the diffuse deformation in the fault zone associated with slow moving faults. The calculation of the 3D tendency of the channel and its projection onto the fault permitted

  20. {sup 40}Ar/{sup 39}Ar thermochronology and thermobarometry of metamorphism, plutonism, and tectonic denudation in the Old Woman Mountains area, California

    SciTech Connect

    Foster, D.A.; Miller, C.F.; Harrison, T.M.; Hoisch, T.D.

    1992-02-01

    Discrimination of individual tectonometamorphic events in polymetamorphosed terranes requires a comprehensive understanding of the relative timing and conditions of metamorphism and plutonism. We have applied a combination of {sup 40}Ar/{sup 39} Ar thermochronology, petrology, and thermobarometry to reconstruct the complex Early Proterozoic through early Cenozoic tectonic and metamorphic evolution of continental crust in the Old Woman Mountains area, southeastern California. Strong Mesozoic thermal events obscure the earlier history in much of the Old Woman Mountains area. In those areas where Early Proterozoic rocks underwent only lower-greenschist-facies metamorphism during the Mesozoic, thermobarometry of pelitic schists indicates that Proterozoic metamorphism occurred at 9 to 11 kbar and {approximately}700 {degrees}C. {sup 40}Ar/{sup 39}Ar ages of hornblende from samples of interbedded Proterozoic amphibolite indicate that this high-grade metamorphism took place before 1600 Ma. The relatively high-pressure conditions of Early Proterozoic metamorphism in the Old Woman Mountains area contrast with the low-pressure granulite-facies metamorphism that occurred elsewhere in the Mojave Desert at this time. {sup 40}Ar/{sup 39}Ar analyses of hornblende from Proterozoic rocks within Mesozoic shear zones and hornblende barometry from Jurassic intrusive rocks suggest that tectonism and burial of Paleozoic strata to >10 km began between 170 and 150 Ma. This tectonism resulted in regional greenschist-facies metamorphism. Late-stage mineral assemblages in Proterozoic and Paleozoic pelitic rocks in the Old Woman Mountains area indicate an increase in metamorphic grade from greenschist to upper amphibolite facies toward Later Cretaceous Plutons of the 73 Ma Old Woman-Piute batholith. Barometric calculations from garnet-bearing metamorphic rocks suggest that this Cretaceous metamorphism took place at 3.5 to 5.0 kbar in the Old Woman Mountains. 68 refs., 11 figs., 3 tabs.

  1. Late Pleistocene to Historical Activity of the Hovd Fault (Mongolian Altay) from Tectonic Geomorphology and Paleoseismology

    NASA Astrophysics Data System (ADS)

    Ferry, M. A.; Battogtokh, D.; Ritz, J. F.; Kurtz, R.; Braucher, R.; Klinger, Y.; Ulzibat, M.; Chimed, O.; Demberel, S.

    2015-12-01

    Active tectonics of western Mongolia is dominated by large strike-slip fault systems that produced great historical earthquakes: the Bulnay fault (Mw 8.1 and 8.4 in 1905), the Fu-Yun fault (Mw 8.0 in 1931) and the Bogd fault (Mw 8.1 in 1957). Central to these faults is the Altay Range that accommodates ~4 mm/yr of right-lateral motion. An earthquake of similar magnitude occurred in 1761 and has been attributed to the Hovd fault were seemingly fresh surface rupture was reported in 1985. Here, we study the Ar-Hötöl section of the Hovd fault where surface rupture was described over a length of ~200 km. Detailed mapping of stream gullies from high-resolution Pleiades satellite images show a consistent pattern of right-lateral offsets from a few meters to ~500 m. At Climbing Rock, we surveyed a gully offset by 75 ± 5 m. The associated surface was sampled for 10Be profile which yields an exposure age of 154 ± 20 ka. The resulting minimal right-lateral slip rate ranges 0.4-0.6 mm/yr. However, drainage reconstruction suggests this surface may have recorded as much as 400 ± 20 m of cumulative offset. This implies the Hovd fault may accommodate as much as 2.6 ± 0.4 mm/yr, which would make it the main active fault of the Altay. At a smaller scale, TLS topography documents offsets in the order of 2.5-5 m that likely correspond to the most recent surface-rupturing event with Mw ~8. A value of 2.8-3.0 m is reconstructed from a Uiger grave dated AD 750-840. At Marmot Creek and Small Creek, short drainages flow across the fault and form ponds against the main scarp. Two paleoseimic trenches reveal similar stratigraphy with numerous peat layers that developed over alluvial sands. The fault exhibits near vertical strands affecting pre-ponding units as well as a well-developed peat unit radiocarbon-dated AD 1465-1635. This unit likely corresponds to the ground surface at the time of the last rupture. It is overlain with a sandy pond unit on top of which a second continuous peat

  2. Reappraisal of the 1887 Ligurian earthquake (western Mediterranean) from macroseismicity, active tectonics and tsunami modelling

    NASA Astrophysics Data System (ADS)

    Larroque, C.; Scotti, O.; Ioualalen, M.; Hassoun, V.; Migeon, S.

    2012-04-01

    Early in the morning, of February 23, 1887 a major damaging earthquake hit the towns along the Italian and French Riviera. The earthquake was followed by a tsunami wave with a maximum runup of 2 m near Imperia. At least 600 hundred people died, mainly due to building collapses. The "Ligurian earthquake" occurred at the junction between the Southern French-Italian Alps and the Ligurian Basin in the western Mediterranean. For such historical event, the epicentre and the equivalent magnitude are difficult to characterize with a high degree of precision, and the tectonic fault responsible for the earthquake is still debated today. The recent MALISAR marine geophysical survey allowed identifying a set of N60-70°E recent scarps at the foot of the northern Ligurian margin, revealing a large system of active faults. The scarps correspond to cumulative reverse faulting, with a minor strike-slip component, consistent with the present-day kinematics of earthquakes. Since we have also identified submarine failures in the time-range of the Ligurian earthquake we addressed the question of the submarine slide-induced tsunami. Nevertheless, the maximum volume involved by these submarine slides was in the range of 0.005 km3. Such a volume appears too small to trigger a tsunami with the observed extent and run-up characteristics. Therefore, we propose that the rupture of fault segments belonging to the 80 km-long northern Ligurian Faults system is the source of the 1887 Ligurian earthquake. We investigate the macroseismic data from the historical databases SISFRANCE-08 and DBMI-04 using several models of intensity attenuation with distance and focal depth. Modelling results are consistent with the location offshore, indicating an epicentre around 43.70°-43.78°N and 7.81°-8.07°E with a magnitude Mw in the range of 6.3-7.5. A refinement of this range of magnitude is discussed in the light of the tsunami modelling. Numerous earthquake sources scenarios have been tested with

  3. Kinematics of the mosquito terrane, Coldfoot Area, Alaska: Keys to Brooks Range tectonics: Final report, Project No. 2

    SciTech Connect

    Harms, T.A.; Coney, P.J.

    1988-04-01

    Within the large-scale geometry of the Brooks Range, the Angayucham terrane occurs as a vast overthrust sheet. From the north flank of the Ruby terrane it underlies the Koyukuk basin and stretches north as the roof thrust to the various nappe terranes of the Brooks Range. The tectonic relationship of the Ruby terrane to the south flank of the Brooks Range lies largely obscured beneath the Angayucham in the eastern apex of the Koyukuk basin. The Mosquito terrane occurs as a window through the Angayucham at this juncture. The composition and structures of the Mosquito terrane reveal that is the result of shear along a sub-horizontal step or flange within the prominent, through-going dextral strike-slip fault system which cuts across the eastern Koyukuk basin and southeastern Brooks Range. Units of the Mosquito were derived from both the Angayucham and Ruby terranes. A consistent tectonic fabric imposed upon them is kinematically linked to the strike-slip system and indicates a northeasterly direction of transport across the terrane. The presence of Ruby-correlative units within the Mosquito suggests the Ruby underlies the Angayucham and that it is in contact with terrances of the southern Brooks Range at that structural level along high-angle strike-slip faults. These relationships demonstrate that an episode of dextral transpression is the latest in the history of terrane accretion and tectonic evolution of the Brooks Range. 35 refs.

  4. Estimate of the post-Last Glacial Maximum tectonic subsidence and attempt to elucidate the subsurface geometry of the active Shanchiao Fault in the Taipei metropolis, Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, C.; Lee, J.; Chan, Y.; Lu, C.; Teng, L. S.

    2011-12-01

    The Taipei Metropolis, home to some 10 million people, is subject to seismic hazard originated from not only ground shaking in thick alluvial deposits due to distant faults or sources scattered throughout the Taiwan region, but also active faulting directly underneath. Northern Taiwan including the Taipei region is currently affected by post-orogenic (Plio-Pleistocene arc-continent collision) processes related to backarc extension of the Ryukyu subduction system. The Shanchiao Fault, an active normal fault outcropping along the western boundary of the Taipei Basin and dipping to the east, is investigated here for the areal extent and magnitude of its recent activity. Based on the growth faulting analysis in the Wuku profile in the central portion of the fault, one key horizon - the top of the Jingmei Conglomerate which was an alluvial fan formed rapidly when a major drainage reorganization occurred during the Last Glacial Maximum - serves to be the marker of tectonic subsidence since its inception around 23 ka. A determination and compilation of the depths of the Jingmei Conglomerate top horizon from nearly 500 borehole records within the Taipei Basin demonstrates that the hanging-wall deforms in a roll-over fashion and the offset is largest in the Wuku-Luzhou area in the central portion of the fault and decreases toward the southern tip of the fault. A geologic profile across the fault zone in the Luzhou area reveals the similar main-branch fault half-negative flower structural pattern observed in the Wuku profile, a phenomenon we interpreted to be originated from the geometry of the basin basement and the strong rheological contrast between unconsolidated basin sediments and basement rocks. We also attempt to resolve the poorly-known subsurface geometry of the Shanchiao Fault by simple elastic dislocation models. The surface deformation recorded by the above compilation is representative of the latest Quaternary period as it spans probably more than 10 earthquake

  5. Input of UAV, DTM photo-interpretation and SAR interferometry on active tectonics applied on the Southern Coastal Range (SE Taiwan)

    NASA Astrophysics Data System (ADS)

    Deffontaines, Benoit; Chang, Kuo-Jen; Champenois, Johann; Magalhaes, Samuel; Serries, Gregory

    2016-04-01

    prove the injection of the Lichi melange within the maximum deformation area especially within the southern Longitudinal Valley Fault and the Pinantahsi river. To conclude, we now have the data (quality, quantity) in order to reconstruct correctly the geology of the surface of Taiwan which will help to better constrain the deepest structures of the island as well as seismic hazards. References : Champenois, J., Fruneau, B., Pathier, E., Deffontaines, B., Lin, K.C. & Hu, J.C., 2012. Monitoring of active tectonic deformations in the Longitudinal Valley (Eastern Taiwan) using Persistent Scatterer InSAR method with ALOS PALSAR data, Earth and Planetary Science Letters, 337-338, 144-155. Wang, Y., & Chen, W. S., 1993. Geological map of eastern Coastal Range, Central Geological Survey, scale 1:100,000.

  6. Evaporite sedimentation in a tectonically active basin: The lacustrine Las Minas Gypsum unit (Late Tortonian, SE Spain)

    NASA Astrophysics Data System (ADS)

    Ortí, Federico; Rosell, Laura; Gibert, Lluís; Moragas, Mar; Playà, Elisabet; Inglès, Montserrat; Rouchy, Jean Marie; Calvo, José Pedro; Gimeno, Domingo

    2014-08-01

    Evaporite successions may undergo significant lithostratigraphic changes laterally and vertically in tectonically-active basins. The Las Minas Gypsum, a lacustrine unit of Late Tortonian age and up to 160 m thick in the Las Minas-Camarillas basin (SE Spain), consists of a number of shallowing-upward cycles. Each cycle is made up of a lower interval with marl and carbonate, and an upper interval with gypsum. In the upper interval, the base displays carbonate-gypsum laminites (couplets, yearly microcycles) showing a large variability of textures and fabrics; gypsum textures are cumulates and bottom-grown crystals. Laminites are overlain by selenitic gypsum. The carbonate is a primary dolomite induced by sulphate-reducing bacterial activity. Native sulphur was formed in early diagenesis and during exhumation was partly transformed into late diagenetic gypsum. The isotopic compositions of gypsum suggest that the sulphate mainly derived from chemical recycling of Triassic evaporites; however, marine sulphate was probably supplied by episodic marine incursions. A perennial saline lake characterized by irregular bottom topography and depositional settings with variable subsidence ratios is interpreted. In addition to climate, saline diapirism, Neogene volcanism, synsedimentary faulting and seismicity influenced the evaporitic deposition. Las Minas-Camarillas basin is an example of how in tectonically active zones different factors interplay to produce significant variability of the evaporitic sedimentation and cyclicity.

  7. Geodynamic significance of the TRM segment in the East African Rift: active tectonics and paleostress in western Tanzania

    NASA Astrophysics Data System (ADS)

    Delvaux, D.; Kervyn, F.; Macheyeki, A. S.; Temu, E. B.

    2012-04-01

    The Tanganyika-Rukwa-Malawi (TRM) rift segment in western Tanzania is a key sector for understanding the opening dynamics of the East African rift system (EARS). In an oblique opening model, it is considered as a dextral transfer fault zone that accommodates the general opening of the EARS in a NW-SE direction. In an orthogonal opening model, it accommodates pure dip-slip normal faulting with extension orthogonal to the rift segments and a general E-W extension for the entire EARS. We investigated the active tectonic architecture and paleostress evolution of the Ufipa plateau and adjacent Rukwa basin and in order to define their geodynamic role in the development of the EARS and highlight their pre-rift brittle tectonic history. The active fault architecture, fault-kinematic analysis and paleostress reconstruction show that the recent to active fault systems that control the rift structure develop in a pure extensional setting with extension direction orthogonal to the trend of the TRM segment. Two pre-rift brittle events are evidenced. An older brittle thrusting is related to the interaction between the Bangweulu block and the Tanzanian craton during the late Pan-African (early Paleozoic). It was followed by a transpressional inversion during the early Mesozoic. This inversion stage caused dextral strike-slip faulting along the fault systems that now control the major rift structures. It has been erroneously interpreted as related to the late Cenozoic EARS which instead is characterized by pure normal faulting.

  8. Tectonics and Volcanism of East Africa as Seen Using Remote Sensing Imagery

    NASA Technical Reports Server (NTRS)

    Hutt, Duncan John

    1996-01-01

    The East African Rift is the largest area of active continental geology. The tectonics of this area has been studied with remote sensing data, including AVHRR, Landsat MSS and TM, SPOT, and electronic still camera from Shuttle. Lineation trends have been compared to centers of volcanic and earthquake activity as well as the trends shown on existing geologic maps. Remote sensing data can be used effectively to reveal and analyze significant tectonic features in this area.

  9. Seismicity and active tectonics in the Alboran Sea, Western Mediterranean: Constraints from an offshore-onshore seismological network and swath bathymetry data

    NASA Astrophysics Data System (ADS)

    Grevemeyer, Ingo; Gràcia, Eulàlia; Villaseñor, Antonio; Leuchters, Wiebke; Watts, Anthony B.

    2015-12-01

    Seismicity and tectonic structure of the Alboran Sea were derived from a large amphibious seismological network deployed in the offshore basins and onshore in Spain and Morocco, an area where the convergence between the African and Eurasian plates causes distributed deformation. Crustal structure derived from local earthquake data suggests that the Alboran Sea is underlain by thinned continental crust with a mean thickness of about 20 km. During the 5 months of offshore network operation, a total of 229 local earthquakes were located within the Alboran Sea and neighboring areas. Earthquakes were generally crustal events, and in the offshore domain, most of them occurred at crustal levels of 2 to 15 km depth. Earthquakes in the Alboran Sea are poorly related to large-scale tectonic features and form a 20 to 40 km wide NNE-SSW trending belt of seismicity between Adra (Spain) and Al Hoceima (Morocco), supporting the case for a major left-lateral shear zone across the Alboran Sea. Such a shear zone is in accord with high-resolution bathymetric data and seismic reflection imaging, indicating a number of small active fault zones, some of which offset the seafloor, rather than supporting a well-defined discrete plate boundary fault. Moreover, a number of large faults known to be active as evidenced from bathymetry, seismic reflection, and paleoseismic data such as the Yusuf and Carboneras faults were seismically inactive. Earthquakes below the Western Alboran Basin occurred at 70 to 110 km depth and hence reflected intermediate depth seismicity related to subducted lithosphere.

  10. Terrestrial source to deep-sea sink sediment budgets at high and low sea levels: Insights from tectonically active Southern California

    USGS Publications Warehouse

    Covault, J.A.; Romans, B.W.; Graham, S.A.; Fildani, A.; Hilley, G.E.

    2011-01-01

    Sediment routing from terrestrial source areas to the deep sea influences landscapes and seascapes and supply and filling of sedimentary basins. However, a comprehensive assessment of land-to-deep-sea sediment budgets over millennia with significant climate change is lacking. We provide source to sink sediment budgets using cosmogenic radionuclide-derived terrestrial denudation rates and submarine-fan deposition rates through sea-level fluctuations since oxygen isotope stage 3 (younger than 40 ka) in tectonically active, spatially restricted sediment-routing systems of Southern California. We show that source-area denudation and deep-sea deposition are balanced during a period of generally falling and low sea level (40-13 ka), but that deep-sea deposition exceeds terrestrial denudation during the subsequent period of rising and high sea level (younger than 13 ka). This additional supply of sediment is likely owed to enhanced dispersal of sediment across the shelf caused by seacliff erosion during postglacial shoreline transgression and initiation of submarine mass wasting. During periods of both low and high sea level, land and deep-sea sediment fluxes do not show orders of magnitude imbalances that might be expected in the wake of major sea-level changes. Thus, sediment-routing processes in a globally significant class of small, tectonically active systems might be fundamentally different from those of larger systems that drain entire orogens, in which sediment storage in coastal plains and wide continental shelves can exceed millions of years. Furthermore, in such small systems, depositional changes offshore can reflect onshore changes when viewed over time scales of several thousand years to more than 10 k.y. ?? 2011 Geological Society of America.

  11. The Boring Volcanic Field of the Portland-Vancouver area, Oregon and Washington: tectonically anomalous forearc volcanism in an urban setting

    USGS Publications Warehouse

    Evarts, Russell C.; Conrey, Richard M.; Fleck, Robert J.; Hagstrum, Jonathan T.; O'Connor, Jim; Dorsey, Rebecca; Madin, Ian P.

    2009-01-01

    More than 80 small volcanoes are scattered throughout the Portland-Vancouver metropolitan area of northwestern Oregon and southwestern Washington. These volcanoes constitute the Boring Volcanic Field, which is centered in the Neogene Portland Basin and merges to the east with coeval volcanic centers of the High Cascade volcanic arc. Although the character of volcanic activity is typical of many monogenetic volcanic fields, its tectonic setting is not, being located in the forearc of the Cascadia subduction system well trenchward of the volcanic-arc axis. The history and petrology of this anomalous volcanic field have been elucidated by a comprehensive program of geologic mapping, geochemistry, 40Ar/39Ar geochronology, and paleomag-netic studies. Volcanism began at 2.6 Ma with eruption of low-K tholeiite and related lavas in the southern part of the Portland Basin. At 1.6 Ma, following a hiatus of ~0.8 m.y., similar lavas erupted a few kilometers to the north, after which volcanism became widely dispersed, compositionally variable, and more or less continuous, with an average recurrence interval of 15,000 yr. The youngest centers, 50–130 ka, are found in the northern part of the field. Boring centers are generally monogenetic and mafic but a few larger edifices, ranging from basalt to low-SiO2 andesite, were also constructed. Low-K to high-K calc-alkaline compositions similar to those of the nearby volcanic arc dominate the field, but many centers erupted magmas that exhibit little influence of fluids derived from the subducting slab. The timing and compositional characteristics of Boring volcanism suggest a genetic relationship with late Neogene intra-arc rifting.

  12. Magnetic Data Interpretation for the Source-Edge Locations in Parts of the Tectonically Active Transition Zone of the Narmada-Son Lineament in Central India

    NASA Astrophysics Data System (ADS)

    Ghosh, G. K.

    2016-02-01

    The study has been carried out in the transition zone of the Narmada-Son lineament (NSL) which is seismically active with various geological complexities, upwarp movement of the mantle material into the crust through fault, fractures lamination and upwelling. NSL is one of the most prominent lineaments in central India after the Himalaya in the Indian geology. The area of investigation extends from longitude 80.25°E to 81.50°E and latitude 23.50°N to 24.37°N in the central part of the Indian continent. Different types of subsurface geological formations viz. alluvial, Gondwana, Deccan traps, Vindhyan, Mahakoshal, Granite and Gneisses groups exist in this area with varying geological ages. In this study area tectonic movement and crustal variation have been taken place during the past time and which might be reason for the variation of magnetic field. Magnetic anomaly suggests that the area has been highly disturbed which causes the Narmada-Son lineament trending in the ENE-WSW direction. Magnetic anomaly variation has been taken place due to the lithological variations subject to the changes in the geological contacts like thrusts and faults in this area. Shallow and deeper sources have been distinguished using frequency domain analysis by applying different filters. To enhance the magnetic data, various types of derivatives to identify the source-edge locations of the causative source bodies. The present study carried out the interpretation using total horizontal derivative, tilt angle derivative, horizontal tilt angle derivative and Cos (θ) derivative map to get source-edge locations. The results derived from various derivatives of magnetic data have been compared with the basement depth solutions calculated from 3D Euler deconvolution. It is suggested that total horizontal derivative, tilt angle derivative and Cos (θ) derivative are the most useful tools for identifying the multiple source edge locations of the causative bodies in this tectonically active

  13. Tectonic Windows Reveal Off-axis Volcanic and Hydrothermal Activity and Along-strike Variations in Eruption Effusion Rates

    NASA Astrophysics Data System (ADS)

    MacDonald, K. C.

    2005-12-01

    Alvin transects of faulted escarpments 50-500m high provide tectonic windows to investigate the top 500m of oceanic crustal structure and lava stratigraphy. The Alvin archives were used to review dives from the East Pacific Rise, the Mid-Atlantic Ridge, the Juan de Fuca Ridge, the Blanco Trough, Cayman Trough and the Galapagos Spreading Center. A spreading rate dependence in lava morphology based solely on areal coverage(Bonatti and Harrison, 1988) was confirmed in scarp transects: mostly pillow lavas at slow spreading rates and sheet flows/lobate flows at faster spreading rates. More interestingly; there is a systematic variation within first, second and third order segments on intermediate and fast-spreading centers such that sheet/lobate flows dominate at segment centers and pillow flows and lava domes are more common at segment ends. This confirms earlier studies which were based on areal coverage (White et al, 2000, 2002, Soule et al 2005). This suggests higher eruption effusion rates and perhaps higher magma pressure and lower magma viscosity at segment centers relative to segment ends. This has important implications for the relationship between segmentation, magma supply, volcanism and hydrothermal activity (Haymon and White 2005). A conundrum remains; based on areal photographic surveys, why are pillow lavas so much more common off-axis than on-axis for intermediate to fast-spreading ridges? If there is an eruption cycle in which sheeted and lobate flows dominate early on, and pillow lavas dominate the waning stages of eruption (e.g. Ballard et al 1979), then more pillow lavas should be seen on axis than are seen on-axis in either areal or transect data. Another explanation is that pillow lavas off-axis are primarily produced by off-axis eruptions (except near segment ends, they may also occur as the pillowed terminations of channeled sheet and lobate flows; the association with channels will make this obvious.) Off-axis volcanism is also indicated by a

  14. Quaternary migration of active extension revealed by a syn-tectonic alluvial fan shift. A case study in the Northern Apennines of Italy

    NASA Astrophysics Data System (ADS)

    Mirabella, Francesco; Bucci, Francesco; Cardinali, Mauro; Santangelo, Michele; Guzzetti, Fausto

    2016-04-01

    In areas characterized by the progressive migration of active extension through time, shifts in the position of the active depocenter occur. Such shifts through time produces peculiar geomorphological settings that are often characterized by wind gaps, abandoned valleys, streams captures and drainage inversions. These features provide the opportunity to investigate active areas by studying the recent-most geological history of the related nearby basins. We investigate this topic in a tectonically active area in the Northern Apennines of Italy, as indicated by both instrumental and historical seismicity (maximum epicentral intensity I0=VIII) and extension rates in the order of 2.5-2.7 mm/yr. In particular, we study the Montefalco ridge drainage inversion. Here, fluvial sands and imbricated conglomerates deposited in a lower Pleistocene depocenter constituted by an extensional subsiding basin, are presently uplifted more than 200 m above the present day alluvial plain. The Montefalco ridge drainage inversion, at about 400 m a.s.l., separates two valleys, the Gualdo Cattaneo - Bastardo valley to the West (300 m a.s.l.) and the Foligno present-day alluvial plain to the East (200 m a.s.l.). Seismic reflection data show that the maximum thickness of the continental sequence in the Foligno valley is in the order of 500 m. This valley is presently occupied by a 37 km2 alluvial fan produced by the Topino river flowing from NE to SW. To unravel the Quaternary tectonic evolution of the area, we integrate different data sets collected by field mapping, detailed photo-geological data, sediments provenance information, and subsurface data. We interpret the Montefalco ridge as a paleo-Foligno-like alluvial fan representing the evidence of the recent migration of the active extension to the East of around 7 km. Considering an age of deformation of 2.5 My, an extension rate of about 2.8 mm/yr is derived, which corresponds to the present-day geodetic rates. We stress the importance

  15. Interplay Between Tectonics And Volcanic Processes Active In The Yellowstone Caldera Detected Via DInSAR And GPS Time-Series

    NASA Astrophysics Data System (ADS)

    Tizzani, Pietro; Battaglia, Maurizio; Castaldo, Raffaele; Pepe, Antonio; Zeni, Giovanni; Lanari, Riccardo

    2014-05-01

    We discriminate and quantify the effects of different stress sources that are active in the Yellowstone volcanic region. In particular, the use of long-term deformation time series allows us to separate the spatial and temporal contributions of the regional tectonic field due to North American (NA) plate motion from the dynamic of magmatic/hydrothermal sources beneath the caldera area. Yellowstone volcano was formed by three major caldera forming eruptions that occurred around 2.0, 1.3 and 0.64 Ma, the most recent one responsible for the 60 km-wide and 40 km-long Yellowstone caldera. Two structural resurgent domes emerged after the last caldera forming eruption: the Mallard Lake (ML) resurgent dome in the southwestern region of Yellowstone caldera, and the Sour Creek (SC) resurgent dome in the northeast part of the caldera. In this work, we extensively exploit DInSAR and GPS measurements to investigate surface deformation at Yellowstone caldera over the last 18 years. We start by analyzing the 1992-2010 deformation time series retrieved by applying the Small BAseline Subset (SBAS) DInSAR technique. This allows us identifying three macro-areas: i) Norris Geyser Basin (NGB), ii) ML and SC resurgent domes and iii) Snake River Plain (SRP), characterized by unique deformation behaviors. In particular, SRP shows a signal related to tectonic deformation, while the other two regions are influenced by the caldera unrest. To isolate the deformation signals related to different stress sources in the Yellowstone caldera, we also remove from the retrieved mean deformation velocity maps the mean displacement rate associated to the northern sector of the Snake River Plain. This latter is the result of tectonic processes controlled by complex interactions between the NA plate, moving in the ENE - WSW direction with a rate of about 2 cm/yr, and the flow of the asthenosphere plume beneath the Yellowstone volcanic region. These de-trended data allow recognizing four major deformation

  16. Late Pleistocene and Holocene uplift history of Cyprus: implications for active tectonics along the southern margin of the Anatolian microplate

    USGS Publications Warehouse

    Harrison, R.W.; Tsiolakis, E.; Stone, B.D.; Lord, A.; McGeehin, J.P.; Mahan, S.A.; Chirico, P.

    2013-01-01

    The nature of the southern margin of the Anatolian microplate during the Neogene is complex, controversial and fundamental in understanding active plate-margin tectonics and natural hazards in the Eastern Mediterranean region. Our investigation provides new insights into the Late Pleistocene uplift history of Cyprus and the Troodos Ophiolite. We provide isotopic (14C) and radiogenic (luminescence) dates of outcropping marine sediments in eastern Cyprus that identify periods of deposition during marine isotope stages (MIS) 3, 4, 5 and 6. Past sea-levels indicated by these deposits are c. 95±25 m higher in elevation than estimates of worldwide eustatic sea-level. An uplift rate of c. 1.8 mm/year and possibly as much as c. 4.1 mm/year in the past c. 26–40 ka is indicated. Holocene marine deposits also occur at elevations higher than those expected for past SL and suggest uplift rates of c. 1.2–2.1 mm/year. MIS-3 marine deposits that crop out in southern and western Cyprus indicate uniform island-wide uplift. We propose a model of tectonic wedging at a plate-bounding restraining bend as a mechanism for Late Pleistocene to Holocene uplift of Cyprus; uplift is accommodated by deformation and seismicity along the margins of the Troodos Ophiolite and re-activation of its low-angle, basal shear zone.

  17. Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins

    USGS Publications Warehouse

    Cartwright, Richard; Clayton, Jordan A.; Kirk, Randolph L.

    2011-01-01

    Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0–5.0) for dendritic networks; comparisons with Rb values determined for Titanbasins, in conjunction with similarities in network patterns, suggest that portions of Titan's north polar region are modified by tectonic forces. Sufficient elevation data existed to calculate bed slope and potential fluvial sedimenttransport rates in at least one Titanbasin, indicating that 75 mm water ice grains (observed at the Huygens landing site) should be readily entrained given sufficient flow depths of liquid hydrocarbons. Volumetric sedimenttransport estimates suggest that ~6700–10,000 Titan years (~2.0–3.0 x 105 Earth years) are required to erode this basin to its minimum relief (assuming constant 1 m and 1.5 m flows); these lowering rates increase to ~27,000–41,000 Titan years (~8.0–12.0 x 105 Earth years) when flows in the north polar region are restricted to summer months.

  18. Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins

    USGS Publications Warehouse

    Cartwright, R.; Clayton, J.A.; Kirk, R.L.

    2011-01-01

    Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0-5.0) for dendritic networks; comparisons with Rb values determined for Titan basins, in conjunction with similarities in network patterns, suggest that portions of Titan's north polar region are modified by tectonic forces. Sufficient elevation data existed to calculate bed slope and potential fluvial sediment transport rates in at least one Titan basin, indicating that 75mm water ice grains (observed at the Huygens landing site) should be readily entrained given sufficient flow depths of liquid hydrocarbons. Volumetric sediment transport estimates suggest that ???6700-10,000 Titan years (???2.0-3.0??105 Earth years) are required to erode this basin to its minimum relief (assuming constant 1m and 1.5m flows); these lowering rates increase to ???27,000-41,000 Titan years (???8.0-12.0??105 Earth years) when flows in the north polar region are restricted to summer months. ?? 2011 Elsevier Inc.

  19. Saturn's Titan: Surface change, ammonia, and implications for atmospheric and tectonic activity

    USGS Publications Warehouse

    Nelson, R.M.; Kamp, L.W.; Matson, D.L.; Irwin, P.G.J.; Baines, K.H.; Boryta, M.D.; Leader, F.E.; Jaumann, R.; Smythe, W.D.; Sotin, C.; Clark, R.N.; Cruikshank, D.P.; Drossart, P.; Pearl, J.C.; Hapke, B.W.; Lunine, J.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, R.Y.; McCord, T.B.; Mennella, V.; Nicholson, P.D.; Sicardy, B.

    2009-01-01

    Titan is known to have a young surface. Here we present evidence from the Cassini Visual and Infrared Mapping Spectrometer that it is currently geologically active. We report that changes in the near-infrared reflectance of a 73,000 km2 area on Titan (latitude 26° S, longitude 78° W) occurred between July 2004 and March of 2006. The reflectance of the area increased by a factor of two between July 2004 and March–April 2005; it then returned to the July 2004 level by November 2005. By late December 2005 the reflectance had surged upward again, establishing a new maximum. Thereafter, it trended downward for the next three months. Detailed spectrophotometric analyses suggest these changes happen at or very near the surface. The spectral differences between the region and its surroundings rule out changes in the distribution of the ices of reasonably expected materials such as H2O, CO2, and CH4 as possible causes. Remarkably, the change is spectrally consistent with the deposition and removal of NH3 frost over a water ice substrate. NH3 has been proposed as a constituent of Titan's interior and has never been reported on the surface. The detection of NH3 frost on the surface might possibly be explained by episodic effusive events occur which bring juvenile ammonia from the interior to the surface. If so, its decomposition would feed nitrogen to the atmosphere now and in the future. The lateral extent of the region exceeds that of active areas on the Earth (Hawaii) or Io (Loki).

  20. Active Tectonics of off-Hokuriku, Central Japan, by two ships seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Kato, Naoko; Sato, Hiroshi; Ishiyama, Tatsuya; Abe, Susumu; Shiraishi, Kazuya

    2015-04-01

    Along the southern to eastern margin of the Sea of Japan, active faults are densely distributed. These submarine active faults produced tsunami disasters, such as 1983 Nihonkai-chubu earthquake (M7.7) and 1993 Hokkaido Nansei-oki earthquake (M7.8). To estimate tsunami hazards, we performed deep seismic reflection profiling to obtain the information of tsunami source faults, off-Hokuriku area in the central part of Honshu, Japan. The survey is carried out as a part of research project named "the integrated research project on seismic and tsunami hazards around the Sea of Japan" funded by MEXT. To obtain long offset data in busy marine activity area, we used two vessels; a gun-ship with 3020 cu. inch air-gun and a cable-ship with a 2-km-long, streamer cable with 156 channels and 480 cu. inch air-gun. Common-midpoint reflection data were acquired using two ships at 4 km offset. The survey area consists of stretched continental crust associated with rifting and opening of the Sea of Japan in early Miocene and is marked by densely distributed syn-rift normal faults. Fault reactivation of normal faults as reverse faults is common. Two phases of fault reactivation are identified from the seismic sections after termination of opening of the Sea of Japan. One is the late Miocene NS trending shortening deformation. This is produced by NS-trending convergence of the Shikoku basin (15 Ma), which belongs to the Philippine Sea plate (PHS) to SW Japan at Nankai trough (Kimura et al., 2005). After the initiation of the subduction of PHS at Nankai trough, the strong shortening deformation is terminated and the fold-and-thrust belt was unconformably covered by sub-horizontal Pliocene sediments. Some horizons of unconformities represent multiple events of shortening driven from the subduction interface. Some normal faults reactivated as active strike-slip and reverse faults in Quaternary. Well observed example is the 2007 Noto peninsula earthquake (M6.8). The 2007 Noto peninsula

  1. Investigating Cenozoic climate change in tectonically active regions with a high-resolution atmospheric general circulation model (ECHAM5)

    NASA Astrophysics Data System (ADS)

    Mutz, Sebastian; Ehlers, Todd; Li, Jingmin; Werner, Martin; Stepanek, Christian; Lohmann, Gerrit

    2016-04-01

    Studies of Cenozoic palaeo-climates contribute to our understanding of contemporary climate change by providing insight into analogues such as the Pliocene (PLIO), and by evaluation of GCM (General Circulation Models) performance using the Mid-Holocene (MH) and the Last Glacial Maximum (LGM). Furthermore, climate is a factor to be considered in the evolution of ecology, landscapes and mountains, and in the reconstruction of erosion histories. In this study, we use high-resolution (T159) ECHAM5 simulations to investigate pre-industrial (PI) and the the above mentioned palaeo-climates for four tectonically active regions: Alaska (St. Elias Range), the US Northwest Pacific (Cascade Range), western South America (Andes) and parts of Asia (Himalaya-Tibet). The PI climate simulation is an AMIP (Atmospheric Model Intercomparison Project) style ECHAM5 experiment, whereas MH and LGM simulation are based on simulations conducted at the Alfred Wegner Institute, Bremerhaven. Sea surface boundary conditions for MH were taken from coupled atmosphere-ocean model simulations (Wei and Lohmann, 2012; Zhang et al, 2013) and sea surface temperatures and sea ice concentration for the LGM are based on GLAMAP project reconstructions (Schäfer-Neth and Paul, 2003). Boundary conditions for the PLIO simulation are taken from the PRISM (Pliocene Research, Interpretation and Synoptic Mapping) project and the employed PLIO vegetation boundary condition is created by means of the transfer procedure for the PRISM vegetation reconstruction to the JSBACH plant functional types as described by Stepanek and Lohmann (2012). For each of the investigated areas and time slices, the regional simulated climates are described by means of cluster analyses based on the variability of precipitation, 2m air temperature and the intra-annual amplitude of the values. Results indicate the largest differences to a PI climate are observed for LGM and PLIO climates in the form of widespread cooling and warming

  2. Neotectonic to Active Tectonic Situation along Ulsan-Yeonil Faults, SE. Korea

    NASA Astrophysics Data System (ADS)

    Choi, S.; Chwae, U.

    2006-05-01

    Characteristics of middle to late Pleistocene faults occurred along NNW Ulsan-Yeonil faults, SE. Korea, have been controverted during last decade due to very short and frequent distribution. Those faults, having NS strike and dip to the east, generally show the top-up-to-the-west movement sense. ESR ages came out 300ka in average and OSL data range 90-50ka. Therefore the faults movement could be considered to two times within 500ka, which indicates capable fault. Earthquake around the region ranges middle to weak. Historic earthquake record described damages of wooden house and some roof tiles, which is not considered as strong as mm6.5-7.0. However tectonic background has been remained yet. In this study, the aim is to figure out geometric relationship between NNW Ulsan fault and Yeonil fault and addresses how the above capable faults have left step pattern of NS strike and left lateral movement sense. As early stage around 23Ma, the eastern block of Yeonil fault had begun to rotate to clockwise due to right lateral movement of two master faults, which are interpreted to Yansan fault and possibly Tsushima tectonic line. Yeonil block, which was in between two master faults, had been undergone the effect of clockwise rotation until around 15ma. The western margin of Yeonil block, which strikes NNW and parallel to sub-parallel to Ulsan fault, had jigsaw-type left lateral movement sense because of the clockwise fan-shape rotation. Among those jigsaw-type fault segments, NS fault segments have been given the westward tectonic pressure since 5Ma. Therefore, small NS-faults have had the top-up-to-the-west movement sense up to present time since after Pliocene and those jigsaw-type fault length yielded to short due to several intermittent shearing along NNW Ulsan fault. As an early product, two Miocene basins developed along Ulsan fault, which strike is not shown because of flat plain.

  3. Tree Tectonics

    NASA Astrophysics Data System (ADS)

    Vogt, Peter R.

    2004-09-01

    Nature often replicates her processes at different scales of space and time in differing media. Here a tree-trunk cross section I am preparing for a dendrochronological display at the Battle Creek Cypress Swamp Nature Sanctuary (Calvert County, Maryland) dried and cracked in a way that replicates practically all the planform features found along the Mid-Oceanic Ridge (see Figure 1). The left-lateral offset of saw marks, contrasting with the right-lateral ``rift'' offset, even illustrates the distinction between transcurrent (strike-slip) and transform faults, the latter only recognized as a geologic feature, by J. Tuzo Wilson, in 1965. However, wood cracking is but one of many examples of natural processes that replicate one or several elements of lithospheric plate tectonics. Many of these examples occur in everyday venues and thus make great teaching aids, ``teachable'' from primary school to university levels. Plate tectonics, the dominant process of Earth geology, also occurs in miniature on the surface of some lava lakes, and as ``ice plate tectonics'' on our frozen seas and lakes. Ice tectonics also happens at larger spatial and temporal scales on the Jovian moons Europa and perhaps Ganymede. Tabletop plate tectonics, in which a molten-paraffin ``asthenosphere'' is surfaced by a skin of congealing wax ``plates,'' first replicated Mid-Oceanic Ridge type seafloor spreading more than three decades ago. A seismologist (J. Brune, personal communication, 2004) discovered wax plate tectonics by casually and serendipitously pulling a stick across a container of molten wax his wife and daughters had used in making candles. Brune and his student D. Oldenburg followed up and mirabile dictu published the results in Science (178, 301-304).

  4. Reflectivity patterns in the Variscan mountain belts and adjacent areas: an attempt for a pattern recognition and correlation to tectonic units

    NASA Astrophysics Data System (ADS)

    Meissner, R.; Wever, Th.; Sadowiak, P.; Dekorp Research Group

    1990-02-01

    The Seismic reflection profiles of DEKORP (DEutsches KOntinentales ReflexionsSeismisches Programm) in the Federal Republic of Germany to date have been limited to areas of the Variscan orogeny. Nevertheless, the character of their reflections differs considerably and may be correlated to certain Variscan and post-Variscan developments. Lower crust lamellae develop in areas of high heat flow, mostly associated with post-Variscan extensional processes; "crocodile" and nappe tectonics are best preserved in the cores and at the flanks of older massifs which were incorporated into the Variscan orogeny. So far poor reflectivity has been observed only in the area of the London-Brabant Massif which was not involved in any of the Phanerozoic orogenies.

  5. Topographic analysis for tectonic geomorphology using digital image processing of elevation data from the Mississippi embayment and adjacent areas

    SciTech Connect

    Mayer, L. . Dept. of Geology)

    1993-03-01

    Image processing of digital elevation data provides a framework within which to evaluate the relative importance of tectonic and erosional signatures on the landscape. Shaded relief imaging of the elevation data illuminates regional topographic features coincident with the physiographic provinces bounding the Mississippi embayment portion of the Coastal Plain: the Ozark Plateaus and Ouachitas on the west, the Central Lowland on the north, and the Interior Low Plateaus on the east. Grayscale or colors from custom color lookup tables are assigned based on elevation. Stretching can be used to enhance a particular elevation range while spatial convolution kernels can be used to provide a robust and rapid means of designing high- and low-pass filters for the purpose of restricting the frequency range examined. Thresholding the elevation ranges and assigning boundaries of the resultant binary images allow for the rapid delineation of topographic contour lines and permits quantization of planform geometry. Forty one-degree by 30-minute quadrangles have been imaged for the purpose of delineating topographic features of possible tectonic origin.

  6. Collision tectonics

    SciTech Connect

    Coward, M.P.; Ries, A.C.

    1985-01-01

    The motions of lithospheric plates have produced most existing mountain ranges, but structures produced as a result of, and following the collision of continental plates need to be distinguished from those produced before by subduction. If subduction is normally only stopped when collision occurs, then most geologically ancient fold belts must be collisional, so it is essential to recognize and understand the effects of the collision process. This book consists of papers that review collision tectonics, covering tectonics, structure, geochemistry, paleomagnetism, metamorphism, and magmatism.

  7. Anatomy of mass transport deposits in the Dead Sea: sedimentary processes in an active tectonic hypersaline basin

    NASA Astrophysics Data System (ADS)

    Waldmann, Nicolas; Hadzhiivanova, Elitsa; Neugebauer, Ina; Brauer, Achim; Schwab, Markus; Frank, Ute; Dulski, Peter

    2014-05-01

    Continental archives such as interplate endorheic lacustrine sedimentary basins provide an excellent source of data for studying regional climate, seismicity and environmental changes through time. Such is the case for the sediments that were deposited in the Dead Sea basin, a tectonically active pull-apart structure along the Dead Sea fault (DSF). This elongated basin is characterized by steep slopes and a deep and flat basin-floor, which are constantly shaped by seismicity and climate. In this study, we present initial results on the sedimentology and internal structure of mass transport deposits in the Pleistocene Dead Sea. The database used for this study consists of a long core retrieved at ~300 m water depth in the deepest part of the Dead Sea as part of an international scientific effort under the auspice of the ICDP. Micro-facies analysis coupled by elemental scanning (µXRF), granulometry and petrophysical measurements (magnetic susceptibility) have been carried out on selected intervals in order to decipher and identify the source-to-sink processes and controlling mechanisms behind the formation of mass transport deposits. The findings of this study allowed defining and characterizing the mass transport deposits into separate sedimentary facies according to the lake level and limnological conditions. Investigating sediments from the deep Dead Sea basin allowed better understanding and deciphering the depositional processes in relation with the tectonic forces shaping this basin.

  8. Regional Tectonic Framework and Human Activities on the North Central Part of The Mexican Volcanic Belt.

    NASA Astrophysics Data System (ADS)

    Nieto-Obregon, J.

    2001-12-01

    Faults and fractures northeasterly oriented dipping NW and SE, with slips mainly normal with a slight left lateral component, affect a suite of rocks of Mesozoic to Pleistocene age, in the area of El Bajio, in the states of Queretaro, Guanajuato, Michoacan, and Aguascalientes. The faults and fractures have affected the infrastructure of the cities and surroundings of Queretaro, Celaya, Salamanca, Irapuato, Silao, Leon and Aguascalientes. In the city of Queretaro, the Tlacote-Balvanera active fault has developed a scarp and its motion may potentially affect life lines of great importance. In Celaya City a N-S trending fault traverses the city and has produced a step wise scarp more than 1.80 m high, damaging houses, streets and life lines. In Salamanca, a fault trending N 60oE, dipping to the SE extends from Cerro Gordo to the SW traversing the city and affecting with a varying degree its infrastructure. Displacements observed within the urban area reach as much as 50 cm. Close to Irapuato City, in a quarry near La Valencianita village, a N 45oE trending fault dipping to the NW affects a lacustrine sequence bearing calcareous horizons. The fault exhibits a throw of 10 m and passes north of the urban area. A similarly oriented fault traverses the city of Irapuato, and near the Traffic Circle of Puente de Guadalupe, changes its strike to the SE and continues to the city limits. In the city of Silao, a fault oriented N 60oE, traverses the city and continues to the SW up to the localities of Venta de Ramales and La Aldea. Important displacements in urban and rural areas reach more than 60 cm. Outside the city of Leon in the junction of the highways to Aguascalientes and Guadalajara a normal fault plane NE oriented and dipping SE shows striations compatible with a normal left lateral motion. Faulting is associated with old buried scarps controlled by pre existing faults, and over exploited aquifers. Some of these faults however are considered potentially active based on

  9. Tectonic map of Uruguay

    NASA Astrophysics Data System (ADS)

    Sanchez Bettucci, L.; Oyhantcabal, P.

    2008-05-01

    A compilation of available data about the geology of Uruguay allowed the definition of its main events and tectonic units. Based on a critical revision of different tectonic hypothesis found in the literature, a parsimonious tectonic evolution schema is presented, in the context of Western Gondwana. The tectonic map illustrates the general features of the structure and main tectonic units of Uruguay. The Precambrian shield, cropping out in the South and Southeast of the country is an Archean to Paleoprtoerozoic basement divided in three main tectonostratigraphic terrranes: the Piedra Alta (PAT) a juvenile Paleoproterozoic unit not reworked by later events; the Nico Pérez (NPT) a complex unit composed of several blocks where Archean to Mesoproterozoic events are recognised. The NPT was strongly reworked by Neoproterozoic (Brasiliano) orogeny. The Dom Feliciano Belt cropping out in eastern Uruguay is related to Western Gondwana amalgamation. Different tectonic settings are considered: pre-Brasiliano Basement inliers; supracrustal successions representing the evolution from a back- arc to a foreland basin; a magmatic arc; and post-collisional basins and related magmatism. In lower Paleozoic the Paraná foreland basin was generated as a consequence of orogenic events. The sedimentary successions in Uruguay include continental to shallow marine deposits where the influence of carboniferous to Permian glacial episode is recorded. The Mesozoic record is characterised by the influence of extension related to the break-up of Gondwana and the formation of the Atlantic Ocean: huge amounts of tholeiitic basalt were erupted (near 30.000 km3 in Uruguay), followed by cretaceous sediments in the northern area of the country while in the south-east, bimodal magmatism and sediments of the same age are associated to rift basins. The Cenozoic is characterised by tectonic quiescence. Subsidence is only observed in the western region (Chaco-Paraná Basin) and in the east (Laguna Mer

  10. Deep seated tectonic-gravitive failure and large landslide in the area from Scilla to Punta Pezzo (Calabria region South Italy)

    NASA Astrophysics Data System (ADS)

    Guerricchio, A.; Doglioni, A.; Simeone, V.

    2012-04-01

    A critical analysis of the morphological characters of the Southern Calabria region in the area from Scilla (RC province- Southern Italy) to Messina Strait show some geomorphological anomalies due to deep tectonic-gravitational failures and landslides induced by the uplift of the same area. The above mentioned phenomena involve, in fact the whole structure of the ridge included between the coastline and Fiumara di Catona (Catona Torrent), starting from Melia Highland (Pian della Melia) towards the promontory of Punta Pezzo on Messina Strait; and have a severe influence on the morphological forms of the territory, on the surface and coastal erosion phenomena and probably, also on the effect of seismic shocks on large engineering works, as the-to-be built Messina Strait bridge, which is very close to Scilla and Punta Pezzo area. The evidence of these failure can be recognized in the arched morphological steps breaking down the crystalline rock masses, but specially in the hydrographic stream network that is so deep and irregular in crystalline rocks that cannot be imputed only to surficial erosion. In fact at the end of the main streams or torrents as Santa Trara or San Gregorio torrents (fiumare) there are not relevant alluvial fan deposits. These tectonic-gravitative failure have been favored by the presence of biotitic schists underlying gneiss and granite rock masses. The first ones has a stiffness lower than the seconds, so they are more deformable. It is also possible that schist rock masses overlie the more deformable phyllite rocks, not outcropping in the area, as it happen in other zones of Calabria region (Guerricchio e Al., 2007). Tectonic-gravitative failures have broken and disarticulated also the terraces of Late Pleistocene deposits lying over the crystalline basement multiplied by these failures, so that may seem terraces of different order. The coastal slope between Gioia Tauro and Scilla is quite high and in a sudden way changes its form just in the

  11. Dynamical parameter analysis of continuous seismic signals of Popocatépetl volcano (Central Mexico): A case of tectonic earthquakes influencing volcanic activity

    NASA Astrophysics Data System (ADS)

    Tárraga, Marta; Cruz-Reyna, Servando; Mendoza-Rosas, Ana; Carniel, Roberto; Martínez-Bringas, Alicia; García, Alicia; Ortiz, Ramon

    2012-06-01

    The continuous background seismic activity contains information on the internal state of a volcanic system. Here, we report the influence of major regional tectonic earthquakes (M > 5 in most cases) on such state, reflected as changes in the spectral and dynamical parameters of the volcano continuous seismic data. Although changes do not always occur, analysis of five cases of earthquake-induced variations in the signals recorded at Popocatépetl volcano in central México reveal significant fluctuations following the tectonic earthquakes. External visible volcanic activity, such as small to moderate explosions and ash emissions, were related to those fluctuations. We briefly discuss possible causes of the variations. We conclude that recognition of fluctuations in the dynamical parameters in volcano monitoring seismic signals after tectonic earthquakes, even those located in the far field, hundreds of kilometers away, may provide an additional criterion for eruption forecasting, and for decision making in the definition of volcanic alert levels.

  12. Evidence for Tectonic Activity During the Mature Harappan Civilization, 2600-1800 BCE

    NASA Astrophysics Data System (ADS)

    Grijalva, K. A.; Kovach, R. L.; Nur, A. M.

    2006-12-01

    The mature Harappan civilization located in Pakistan and India dates from 2600 to 1800 BCE. By combining seismic data, three-dimensional elastic dislocation modeling, and archaeological findings we examined the role that earthquakes played in the demise of Harappan settlements. The study focuses on three different geographical regions: Gujarat, the Sarasvati-Ghaggar-Hakra River valley, and the Makran coast of Pakistan. In Gujarat, the fluvial system of the Rann of Kachchh has undergone significant changes. The Rann of Kachchh formed as a delta for three rivers, becoming an inland sea during the time of Alexander the Great, and ultimately a salty marsh. These changes were brought about by a combination of sea level changes, the truncation of the three rivers by tectonic uplift and the deepening of the Rann by earthquake induced subsidence. Events analogous to the 1819 Allah Bund earthquake, which dammed the Puran River for seven years, would have significantly altered the water source for downstream settlements. Data from the recent 2001 Bhuj event shows that Harappan settlements would have suffered considerable shaking damage from an analogous historical event. Archaeological studies to date have found direct evidence for of at least one large earthquake at Dholavira in 2200 BCE. A number of the mature Harappan settlements are located along the dry Sarasvati-Ghaggar-Hakra river system. The decline of these sites coincides with the divergence of the Sarasvati-Ghaggar-Hakra system to the Indus and Ganga river systems. A succession of earthquakes, along with a period of aridity, likely led to the disappearance of the Sarasvati-Ghaggar-Hakra system. Although this region has not had any large earthquakes in historic times, there is archaeological evidence of two large events at the Harappan site of Kalibangan, at 2900 and 2700 BCE. Along the Makran coast two settlements, believed to have been Harappan seaports, are now located tens of kilometers inland. Changes in sea

  13. Evidence and dating of mid-Cretaceous tectonic activity in the San Rafael Swell, Emery County, Utah

    SciTech Connect

    Eaton, J.G. ); Kirkland, J.I. ); Kauffman, E.G. )

    1990-04-01

    Evidence of tectonic activity in the form of recycled conglomerates has been found in middle Cretaceous deposits on the western flank of the San Rafael Swell. These conglomerates, present in the upper part of the Dakota Formation and in the overlying basal Mancos Shale (Tununk Member), are separated by an earliest Turonian unconformity. The conglomerates appear to be derived from the Lower Cretaceous Buckhorn Conglomerate, or similar conglomerates, which were re-exposed by latest Cenomanian uplift. Coarse clastics provided to the nearshore facies of the Dakota Formation by coastal rivers are preserved as a coarsening upward sequence. Continued uplift eventually caused a local marine regression by temporarily inhibiting the initial (latest Cenomanian) transgression of the Greenhorn Sea. In subaerially exposed environments pebbles and cobbles from the Buckhorn were distributed across the coastal floodplain by rivers. These clasts were reworked into a basal lag deposit when renewed transgression of the Greenhorn Sea occurred during the late early Turonian.

  14. Sedimentology of seismo-turbidites off the Cascadia and northern California active tectonic continental margins, Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Gutierrez Pastor, Julia; Nelson, Hans; Goldfinger, Chris; Escutia, Carlota

    2013-04-01

    Holocene turbidites from turbidite channel systems along the active tectonic continental margins of the Cascadia subduction zone (offshore Vancouver Island to Mendocino Triple Junction) and the northern San Andreas Transform Fault (the Triple Junction to San Francisco Bay), have been analyzed for sedimentologic features related to their seismic origin. Centimeter thick silt/sand beds (turbidite base) capped by mud layers (turbidite tail) and interbedded with hemipelagic silty clay intervals with high biogenic content have been characterized by visual core descriptions, grain-size analysis, X-ray radiographs and physical properties. Along the northern California margin in upstream single tributary canyons and channels, most turbidites are uni-pulsed (classic fining up) whereas downstream below multiple tributary canyon and channel confluences, most deposits are stacked turbidites. Because each set of stacked turbidites has no hemipelagic sediment between each turbidite unit and each unit has a distinct mineralogy from a different tributary canyon, we interpret that a stacked turbidite is deposited by several coeval turbidity currents fed by multiple tributary canyons and channels with synchronous triggering from a single San Andreas Fault earthquake. The Cascadia margin is characterized by individual multi-pulsed turbidites that contain multiple coarse-grained sub-units without hemipelagic sediment between pulses. Because the number and character of multiple coarse-grained pulses for each correlative multi-pulsed turbidite is almost always constant both upstream and downstream in different channel systems for 600 km along the margin,we interpret that the earthquake shaking or aftershock signature is usually preserved, for the much stronger Cascadia (≥9 Mw) compared to weaker California (≥8Mw) earthquakes, which result in upstream uni-pulsed turbidites and downstream stacked turbidites. Consequently, both the strongest (≥9 Mw) great earthquakes and downstream

  15. Early Cretaceous tectono-magmatic activity and tectonic implications along the Sulu Orogenic Belt - case study of the Dashan complex

    NASA Astrophysics Data System (ADS)

    Liu, Yanghe; Liu, Junlai; Shi, Xiaoxiao; Yuan, Fengjie; Ni, Jinlong; Wu, Wenbin; Chen, Xiaoyu

    2016-04-01

    The tectonic extension of the eastern Eurasian continent during the Early Cretaceous resulted in widespread occurrence of metamorphic core complexes, wide rifts and related magmatic emplacement, among which the Dashan complex of the Jiaonan orogenic belt is a typical example. The complex is a complex massif of several types of granitic rocks. The core of the complex is composed of massive porphry-bearing biotite-hornblende granitoid without any evidence of ductile deformation. Mylonitized augen quartz monzonite and granodiorite constitute the margin of the complex. A transition zone is composed of porphyritic biotite-hornblende monzonite with weakly orientated K-feldspar phenocryst and mafic microgranular enclave. The foliations along the northwestern margin of the complex dip to NW at with dip angles of about 38°, and along the southwestern and northeastern margins to SE with dip angles of about 45°. Stretching lineations are constantly plunging WNW-ESE with pitch angles between 10° and 40°, which is consistent with the orientation of lineations in the other regions in eastern China. The granites,porphyritic monzogranite and the mafic microgranular enclaves in monzogranite are dated of ca.126Ma. The similarities in ages of crystallization of the monzogranite and its MME's implies the existence of magmatic mixing processes. Meanwhile, the mylonitized augen quartz monzonite and granodiorite along the margins of the complex possess crystallization ages of 129.8±1.1Ma and 132.7±2.8Ma, respectively. The petrographical zonation , structural characteristics and the systematical zircon U-Pb geochronology of the granitic rocks may suggest that the Dashan complex has experienced multistage emplacement under the same tectonic extension setting. In despite of the location of the complex near the Tanlu fault zone, the remarkable consistency of the orientations of stretching lineation of the Dashan complex to those from the other parts of the eastern China area implies

  16. Bathymetric characterization of tectonically active basins in the northern Gulf of California

    NASA Astrophysics Data System (ADS)

    Prol-Ledesma, R. M.; Canet, C.; Dando, P. R.

    2009-04-01

    The Wagner Basin can be considered a "nascent spreading centre" that evolved from a half graben with a thick sediment cover that may mask magmatic activity at depth. The 200-210 m deep Wagner and Consag Basins are the northernmost of the 8 active extensional basins within the Gulf of California rift system and have been assumed to be mostly hydrothermally inactive; however, bathymetric data show dense deep faulting, mainly on the SE edge of the basins; additionally, the presence of extensive gas venting and heated sediments along the Wagner Fault was observed. Detailed bathymetry of the Wagner and Consag Basins shows the steep eastern edge of the basins bordered by the Wagner Fault. Bathymetry and profiler data revealed large vertical displacements due to faulting that disrupted the sedimentary column. More than 246 bubble plumes were mapped on the echo-sounder profiles, many rising to the surface from 65 -150 m depth and the area affected by low bottom pH, due to CO2 discharge, was in excess of 365 km2. Bubbles were observed breaking the sea surface from some large plumes. Only a minority of the vents present were mapped with the echo-sounders, since the closest survey lines were 1km apart. Based on the bottom coverage of the acoustic beam we estimate that there are at least 15,000 individual gas vents along the Wagner fault. Profiler images showed gas channels and chimneys associated with sedimentary layers. The gas plumes originated from sites of intense disruptions of the upper sediments (synsedimentary faults, pockmarks, mud domes and diapirs and raised irregular hard reflectors). Beneath the plumes, there were enhanced sedimentary reflectors and acoustic blanking indicative of subsurface gas accumulation. One of the strongest vents was associated with a mud diapir. Cemented sediments were common inside pockmarks and around gas outlets; 13 (22%) of grab and box core samples in the outgassing area contained these but in many cases the grab was empty after

  17. A seismic sequence from Northern Apennines (Italy) provides new insight on the role of fluids in the active tectonics of accretionary wedges

    NASA Astrophysics Data System (ADS)

    Calderoni, Giovanna; Di Giovambattista, Rita; Burrato, Pierfrancesco; Ventura, Guido

    2009-04-01

    We analyze a seismic sequence which occurred in 2000 along the Northern Apennines accretionary wedge (Italy). The sequence developed within the Cretaceous-Triassic limestones of the tectonic wedge, where methane-rich and oil reservoirs are stored. Ruptures mainly developed on WNW-ESE striking thrusts. The compressive stress field is consistent with that acting at regional scale in Northern Apennines. Seismic parameters indicate that fluids are involved in the seismogenic process. The amplitudes of the P and S phases and data from some stations evidence a P to S conversion within Vp/ Vs = 2.1 layer. The attenuation properties of crust show a higher attenuation zone located west of the epicentral cloud. Eight hundred aftershocks delineate a sub-vertical cloud of events between 7 and 14 km depth. The space-time evolution of the aftershocks is consistent with a diffusive spreading (diffusivity = 1.9 m 2/s) along vertically superimposed thrusts. Diffusion also controls the time evolution of the sequence. Fluid pressure is estimated to be roughly equal to the vertical, lithostatic stress. The overpressure within reservoirs develops by tectonic compaction processes. The fluids upraise along sub-vertical fractures related to the shortening of the wedge. The 2000 sequence occurred in an area that separates a thermal and deeper petroleum system from a shallower biogenic system. The divider of these systems controls the attenuation properties of the crust. The fluid-rock interaction at seismogenetic depth is related to hydrothermal processes more than to compaction. In accretionary wedges, seismicity activating superimposed thrusts may drive methane and oil upraising from the upper crust.

  18. North Chilean forearc tectonics and cenozoic plate kinematics

    NASA Astrophysics Data System (ADS)

    Buddin, Tim S.; Stimpson, Ian G.; Williams, Graham D.

    1993-04-01

    The continental forearc of northern Chile has been subjected to contemporaneous extension and compression. Here, cross-sections constructed across the forearc are presented which show that since initial shortening, deformation of the forearc has occurred in two tectonically distinct areas. These inner and outer forearc areas are separated by the strain discontinuity of the Atacama fault system and the tectonically neutral Central Depression. The outer forearc, the Coastal Cordillera, exhibits extensional tectonics, with large (up to 300 m) normal fault scarps preserved. These faults cut the earlier thrusts responsible for the elevation of Jurassic rocks at the coast above their regional elevation. The normal faults have been re-activated, displacing Quaternary salt deposits in the Salar Grande. This re-activation of the basement faults is probably due to the subduction of anomalously thick oceanic crust, producing an isostatic imbalance in the outer forearc. In the inner forearc, cross-sections through the Sierra del Medio and Cordillera de Domeyko show that structures of the Pre-Cordillera are best explained by a thick-skinned thrust system, with localized thin-skinned tectonics controlled by evaporite detachment horizons. Current forearc deformation features indicate a strong degree of correlation between subduction zone geometry and forearc tectonics. The timing of Cenozoic tectonism also fits well with established plate motion parameters, and the spatial and temporal variation in the state of stress of the forearc shows a close relationship throughout the Cenozoic to the plate kinematics and morphology of the subducting Nazca plate.

  19. Tectonic structure of East Antarctica

    NASA Astrophysics Data System (ADS)

    Leychenkov, German; Grikurov, Garrik; Golynsky, Alexander

    2013-04-01

    First overviews of tectonic structure of the Southern Continent were made by the pioneers of Antarctic earth science investigations almost 100 years ago. Despite rapidly advancing international geological studies under the Antarctic Treaty, the presentations of Antarctic tectonic structure remained largely speculative until the end of the past century when implementation of modern analytical and remote-sensing research technologies enabled compilation of more credible tectonic models of Antarctica. The East Antarctic bedrock consists mainly of the Precambrian crystalline complexes and the Paleozoic-Early Mesozoic platform units. Crystalline Shield is locally complicated by Neoproterozoic aulacogenes and Late Paleozoic to Mesozoic rifts. Shield assemblages reliably recognized in coastal outcrops indicate the predominant occurrence of Archean cratonic nuclei and Mesoproterozoic mobile belts. The undisturbed platform cover strata are exposed in East Antarctica mainly along its boundary with West Antarctica. Tectonic structure of ice-covered regions (more that 99% of the East Antarctic territory) is interpreted using mostly magnetic and bedrock topography data, but other geophysical and geological information (satellite, airborne and over-ice gravity; seismology; active seismics; erratics; detrital zircons dates; etc.) is also important. Archean cratons are geologically documented in western Dronning Maud Land, Enderby Land, Princess Elizabeth Land and in the southern Prince Charles Mts. Their distribution under the ice is marked by a specific magnetic pattern including low-amplitude mosaic and/or high-amplitude long-wavelength anomalies. The most extensive ancient craton being 1000 km across is believed to extend from the southern Prince Charles Mts. to the Gamburtsev Mts. Mesoproterozoic mobile belts are distinguished by elongated high-amplitude magnetic anomalies and are mapped along the costal area as the zone of 250-600 km wide. The Gamburtsev Mts. area is also

  20. Task 1 quarternary tectonics

    SciTech Connect

    Bell, J.W.

    1994-12-31

    Activities on the task of quarternary tectonics for the Yucca Mountain Site investigations are described. Technical topics include: A preliminary reveiw of Bare Mountain Trench; A preliminary detailed lineament map of the Southwestern part of the proposed repository; A discussion on the 1994 Double Spring Flat, Nevada earthquake; and evidence for temporal clustering.

  1. Tapping polyrhythms in music activates language areas.

    PubMed

    Vuust, Peter; Wallentin, Mikkel; Mouridsen, Kim; Ostergaard, Leif; Roepstorff, Andreas

    2011-05-01

    Music is experienced and understood on the basis of foreground/background relationships and tension created between actual music and the underlying meter. Polyrhythms create tension between a counter meter and the main meter. Previously, we have shown that Brodmann area 47 (BA47), a brain area associated with processing of language, is activated bilaterally when musicians tap the main meter in a polymetric context emphasizing a counter meter, suggesting that processing of metric elements in music relies on brain areas also involved in language processing. In that study, the tension was created entirely by changes in the stimulus while participants were tapping the main meter. Here we find left-hemispheric BA47 activation in response to a self-produced counter meter on top of a main meter provided by an ecological music excerpt. This data indicates that the activation is linked to polyrhythmic tension, regardless of whether it arises from the stimulus or the task.

  2. Late Pleistocene to Holocene alluvial tableland formation in an intra-mountainous basin in a tectonically active mountain belt ― A case study in the Puli Basin, central Taiwan

    NASA Astrophysics Data System (ADS)

    Tseng, Chia-Han; Lüthgens, Christopher; Tsukamoto, Sumiko; Reimann, Tony; Frechen, Manfred; Böse, Margot

    2016-01-01

    The morphology in Taiwan is a product of high tectonic activity at the convergent margin and East Asian monsoon climate. Tablelands are prominent geomorphic features in the Puli Basin in central Taiwan. These tablelands provide an archive to understand links between past climatic evolution and tectonic events resulting in the formation of the present-day landforms. To establish a geochronological framework for the alluvium underlying the tablelands in the Puli Basin, optically stimulated luminescence dating was applied to obtain burial ages. The numerical data indicate an accumulation phase of alluvial fans in the Late Pleistocene to Early Holocene transition. The study area in the Taomi River catchment, an obvious longer precursor of the Taomi River, originating from west of the Yuchih Basin, transported the sediments forming the present-day southern tablelands. During the Pleistocene-Holocene transition, the climate changed to wetter and warmer conditions, so that slope processes might have changed and an increasing transport in the fluvial system was stimulated. Fluvial and fan terraces in other river catchments in Taiwan also indicate a period of increased fluvial transport and deposition. A geomorphic evolution model in the Puli Basin is reconstructed on the basis of the chronological framework and of sedimentological features. Fluvial processes controlled by climatic change and accompanied by tectonic activities have created the diverse topography in the Puli Basin.

  3. Scenarios for earthquake-generated tsunamis on a complex tectonic area of diffuse deformation and low velocity: The Alboran Sea, Western Mediterranean

    USGS Publications Warehouse

    Alvarez-Gomez, J. A.; Aniel-Quiroga, I.; Gonzalez, M.; Olabarrieta, M.; Carreno, E.

    2011-01-01

    The tsunami impact on the Spanish and North African coasts of the Alboran Sea generated by several reliable seismic tsunamigenic sources in this area was modeled. The tectonic setting is complex and a study of the potential sources from geological data is basic to obtain probable source characteristics. The tectonic structures considered in this study as potentially tsunamigenic are: the Alboran Ridge associated structures, the Carboneras Fault Zone and the Yusuf Fault Zone. We characterized 12 probable tsunamigenic seismic sources in the Alboran Basin based on the results of recent oceanographical studies. The strain rate in the area is low and therefore its seismicity is moderate and cannot be used to infer characteristics of the major seismic sources. These sources have been used as input for the numerical simulation of the wave propagation, based on the solution of the nonlinear shallow water equations through a finite-difference technique. We calculated the Maximum Wave Elevations, and Tsunami Travel Times using the numerical simulations. The results are shown as maps and profiles along the Spanish and African coasts. The sources associated with the Alboran Ridge show the maximum potential to generate damaging tsunamis, with maximum wave elevations in front of the coast exceeding 1.5. m. The Carboneras and Yusuf faults are not capable of generating disastrous tsunamis on their own, although their proximity to the coast could trigger landslides and associated sea disturbances. The areas which are more exposed to the impact of tsunamis generated in the Alboran Sea are the Spanish coast between Malaga and Adra, and the African coast between Alhoceima and Melilla. ?? 2011 Elsevier B.V.

  4. Tectonic Setting and Bimodal Magmatic Evolution of Eocene Volcanic Rocks of the Bijgerd-Kuh-e Kharchin area, Uromieh-Dokhtar Zone, Iran

    NASA Astrophysics Data System (ADS)

    Davarpanah, A.; Khalatbari-Jafari, M.; Babaie, H. A.; Krogstad, E. J.; Mobasher, K.; La Tour, T. E.; Deocampo, D. M.

    2008-12-01

    Geochemical composition and texture of the Middle and Late Eocene volcanic, volcaniclastic, and volcanic- sedimentary rocks in the Bijgerd-Kuh-e Kharchin area, northwest of Saveh, provide significant geochemical and geological clues for the tectonic and magmatic evolution of the Uromieh-Dokhtar volcanic-plutonic zone of Iran. The Middle Eocene volcanic rocks have an intermediate composition and include green tuff and tuffaceous sandstone with intercalated sandstone, sandy tuff, and shale. The shale has lenses of nummulite- bearing limestone with a Middle Eocene detrital age. The time between the Middle and Late Eocene volcanic activities in this area is marked by the presence of andesite and rhyolitic tuff. The Late Eocene succession is distinguished by the presence of four alternating levels (horizons) of intermediate lava and ignimbrite which we designate as Eig. The ignimbrites of the Eig sequence have a rhyolitic composition and include ignimbrite- breccia, ignimbrite-tuff, and ignimbrite-lava pairs. The volume of the felsic volcanic rocks in this sequence far exceeds that of the intermediate rocks, which makes it unlikely that they evolved through the magmatic differentiation of a basaltic magma. The presence of the nummulite-bearing limestone lenses, and sandstone and conglomerate interbeds between the ignimbrites, suggests a shallow marine environment for the pyroclastic deposition and probably the eruptions. The tuff and siltstone of the Est unit that sits above the first ignimbrite may represent deep water, Late Eocene deposit. Oligo-Miocene limestone of the Qom Formation unconformably overlies the uppermost Late Eocene ignimbrite. Washings from red marls give microfossils with Late Eocene age for the Eig sequence, which is synchronous with other paleontological evidence that puts the peak volcanic activity as Late Eocene in the Bijgerd-Kuh-e Kharchin area. Field and petrographic evidence for magma mixing/mingling is given by the presence of mafic

  5. Provenance and sediment-dispersal system in tectonically active rapidly evolving foreland basin, Western Interior

    SciTech Connect

    Khandaker, N.I.; Vondra, C.F.

    1989-03-01

    The Upper Cretaceous Frontier Formation, along the mobile edge of the Western Interior foreland basin, is composed mainly of clastic sediments and was deposited during the initial Late Cretaceous transgressive-regressive phases of the Western Interior seaway across Wyoming. The formation contains many persistent bentonite beds and several sandstone packages in its lower part and a thin, lenticular lithic wacke-polymictic conglomerate association at its upper contact (Torchlight Sandstone Member). Abundant granule to cobble-sized clasts of andesite, granite, chert, and quartzite are set in a poorly sorted sand-to-granule grade volcaniclastic matrix. There is a lithologic continuity of this volcaniclastic unit across the Bighorn Mountains into the Powder River basin. A high-energy distributary complex of sizable areal extent is invoked for the deposition of this linear conglomerate facies. Geochemical investigations of the whole-rock andesite clasts and bentonite allowed more precise definition of character, tectonic setting, and evolutionary stages of sedimentary distributive provinces. Bentonites and andesites are strongly enriched in strontium and barium, but only mildly enriched in heavy rare earth elements and high field-strength elements. These analyzed rocks have trace element characteristics similar in a general way to those of typical orogenic volcanics; they show some significant differences in detail. Composition of volcaniclasts and paleocurrent data indicate a proximal sediment source for the extrabasinal detritus within the Frontier Formation. The possibility of a contribution from a Mesozoic volcanic center in the neighborhood of southwestern Montana is strongly favored. The products of this volcanism constitute an assemblage of deep crustal to mantle( ) derived rocks, and their composition record time-integrated enrichment in light over heavy rare earth elements.

  6. Structural and stratigraphic evolution of the central Mississippi Canyon area: Interaction of salt tectonics and slope processes in the formation of engineering and geologic hazards

    NASA Astrophysics Data System (ADS)

    Brand, John Richard

    Approximately 720 square miles of digital 3-dimensional seismic data covering the eastern Mississippi Canyon area, Gulf of Mexico, continental shelf was used to examine the structural and stratigraphic evolution of the geology in the study area. The analysis focused on salt tectonics and sequence stratigraphy to develop a geologic model for the study area and its potential impact on engineering and geologic hazards. Salt in the study area was found to be established structural end-members derived from shallow-emplaced salt sheets. The transition from regional to local salt tectonics was identified through structural deformation of the stratigraphic section on the seismic data and occurred no later than ˜450,000 years ago. From ˜450,000 years to present, slope depositional processes have become the dominant geologic process in the study area. Six stratigraphic sequences (I-VI) were identified in the study area and found to correlate with sequences previously defined for the Eastern Mississippi Fan. Condensed sections were the key to the correlation. The sequence stratigraphy for the Eastern Mississippi Fan can be extended ˜28 miles west, adding another ˜720 square miles to the interpreted Fan. A previously defined channel within the Eastern Fan was identified in the study area and extended the channel ˜28 miles west. Previous work on the Eastern Fan identified the source of the Fan to be the Mobile River; however, extending the channel west suggests the sediment source to be from the Mississippi River, not the Mobile River. Further evidence for this was found in ponded turbidites whose source has been previously established as the Mississippi River. Ages of the stratigraphic sequences were compared to changes in eustatic sea level. The formation stratigraphic sequences appear decoupled from sea level change with "pseudo-highstands" forming condensed sections during pronounced Pleistocene sea level lowstands. Miocene and Pleistocene depositional analogues

  7. Constraining fault activity by investigating tectonically-deformed Quaternary palaeoshorelines using a synchronous correlation method: the Capo D'Orlando Fault as a case study (NE Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Meschis, Marco; Roberts, Gerald P.; Robertson, Jennifer

    2016-04-01

    Long-term curstal extension rates, accommodated by active normal faults, can be constrained by investigating Late Quaternary vertical movements. Sequences of marine terraces tectonically deformed by active faults mark the interaction between tectonic activity, sea-level changes and active faulting throughout the Quaternary (e.g. Armijo et al., 1996, Giunta et al, 2011, Roberts et al., 2013). Crustal deformation can be calculated over multiple seismic cycles by mapping Quaternary tectonically-deformed palaeoshorelines, both in the hangingwall and footwall of active normal faults (Roberts et al., 2013). Here we use a synchronous correlation method between palaeoshorelines elevations and the ages of sea-level highstands (see Roberts et al., 2013 for further details) which takes advantage of the facts that (i) sea-level highstands are not evenly-spaced in time, yet must correlate with palaeoshorelines that are commonly not evenly-spaced in elevation, and (ii) that older terraces may be destroyed and/or overprinted by younger highstands, so that the next higher or lower paleoshoreline does not necessarily correlate with the next older or younger sea-level highstand. We investigated a flight of Late Quaternary marine terraces deformed by normal faulting as a result of the Capo D'Orlando Fault in NE Sicily (e.g. Giunta et al., 2011). This fault lies within the Calabrian Arc which has experienced damaging seismic events such as the 1908 Messina Straits earthquake ~ Mw 7. Our mapping and previous mapping (Giunta et al. (2011) demonstrate that the elevations of marine terraces inner edges change along the strike the NE - SW oriented normal fault. This confirms active deformation on the Capo D'Orlando Fault, strongly suggesting that it should be added into the Database of Individual Seismogenic Sources (DISS, Basili et al., 2008). Giunta et al. (2011) suggested that uplift rates and hence faults lip-rates vary through time for this examples. We update the ages assigned to

  8. Surface Rupture of the 2005 Kashmir, Pakistan, Earthquake and its Active Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Kaneda, H.; Nakata, T.; Tsutsumi, H.; Kondo, H.; Sugito, N.; Awata, Y.; Akhtar, S. S.; Majid, A.; Khattak, W.; Awan, A. A.; Yeats, R. S.

    2006-12-01

    The 8th October 2005 Kashmir earthquake of Mw 7.6 struck the westernmost area of the Indian-Eurasian collision zone, resulting in the worst earthquake disaster ever recorded along the frontal Himalaya. Although none of the historical Himalayan earthquakes is reported to have produced primary surface rupture, our field mapping reveals that the 2005 earthquake accompanied a NW-trending ~70-km-long distinctive surface rupture with maximum and mean vertical separations of ~7 m and ~3 m, respectively. Typical surface expression of faulting is a NE-side-up fault scarp or warp with surface shortening features at its base and tension cracks on its crest. Bulging and back-tilting are also observed on the upthrown side at many places. The surface rupture is subdivided into three geometrical segments separated by small steps. Location of the hypocenter suggests that the rupture was initiated at a deep portion of the northern-central segment boundary and bilaterally propagated to eventually break three segments. Mapped surface rupture trace clearly shows that neither the Himalayan Frontal Thrust (HFT) nor the Main Boundary Thrust (MBT) is responsible for the earthquake, but a geomorphologically-evident active fault within the Sub-Himalaya, the Balakot-Garhi fault, is a causative fault, although a part of the Balakot-Garhi fault appears to coincide with the surface trace of the MBT. Cumulative vertical separation of the most extensively recognized fluvial terrace surface is 7-8 times larger than the 2005 separation, implying occurrence of 7-8 similar earthquakes after the surface abandonment. If this deeply-incised fill surface is related to sediment yield increase due to the last major glaciation around 20 ka, the rupture interval and vertical slip rate of the Balakot-Garhi fault are estimated to be on the order of ~3000 years and ~1 mm/yr, respectively. By using the seismologically determined fault dip of ~30 degrees, horizontal shortening rate across the fault is then

  9. Seismicity study of volcano-tectonic in and around Tangkuban Parahu active volcano in West Java region, Indonesia

    NASA Astrophysics Data System (ADS)

    Ry, Rexha V.; Priyono, A.; Nugraha, A. D.; Basuki, A.

    2016-05-01

    Tangkuban Parahu is one of the active volcano in Indonesia located about 15 km northern part of Bandung city. The objective of this study is to investigate the seismic activity in the time periods of January 2013 to December 2013. First, we identified seismic events induced by volcano-tectonic activities. These micro-earthquake events were identified as having difference of P-wave and S-wave arrival times less than three seconds. Then, we constrained its location of hypocenter to locate the source of the activities. Hypocenter determination was performed using adaptive simulated annealing method. Using these results, seismic tomographic inversions were conducted to image the three-dimensional velocity structure of Vp, Vs, and the Vp/Vs ratio. In this study, 278 micro-earthquake events have been identified and located. Distribution of hypocenters around Tangkuban Parahu volcano forms an alignment structure and may be related to the stress induced by magma below, also movement of shallow magma below Domas Crater. Our preliminary tomographic inversion results indicate the presences of low Vp, high Vs, and low Vp/Vs ratio that associate to accumulated young volcanic eruption products and hot material zones.

  10. Paleo-surfaces of glacio-eustatically forced aggradational successions in the coastal area of Rome: Assessing interplay between tectonics and sea-level during the last ten interglacials

    NASA Astrophysics Data System (ADS)

    Marra, Fabrizio; Florindo, Fabio; Anzidei, Marco; Sepe, Vincenzo

    2016-09-01

    Recently acquired geochronological and stratigraphic data provide new information on the sedimentary successions deposited by the Paleo-Tiber River in the coastal and near-coastal area of Rome in consequence of the glacio-eustatic changes, allowing to better define their inner geometry and palaeogeographic spatial distribution. In the present work we use this revised sedimentary dataset to provide a geochronologically constrained and tectonically adjusted record of paleo sea-level indicators. Aimed at this scope, we review literature data acquired in the last 35 years and using the new geochronological constraints we pinpoint the coastal-to-fluvial terraces of MIS 5 and MIS 7, mapping their relic surfaces in an area of 30 km along the coast north and south of the Tiber River mouth, and 20 km inland of the fluvial valleys of Tiber and Aniene rivers. The geometry of these paleo-surfaces provides constraints on the relative elevation of the sea-level during the last interglacials and on the uplift rates in this region during the last 200 ka. In particular, we recognize the previously undetected terraces of MIS 5.3 and MIS 5.1 interstadials, and we assess their spatial relationship with respect to MIS 5.5, providing important information on sea-level oscillations during this time span. Comparison with sea-level indicators provided by previous aggradational successions deposited during past interglacials spanning MIS 9 through MIS 21 in the coastal area of Rome, also allows us to reconstruct the tectonic history and investigate its relationships with the Middle-Pleistocene volcanic activity of the Roman Comagmatic Region along the Tyrrhenian Sea margin of Italy in the last 900 ka.

  11. Active tectonics of the Seattle fault and central Puget sound, Washington - Implications for earthquake hazards

    USGS Publications Warehouse

    Johnson, S.Y.; Dadisman, S.V.; Childs, J. R.; Stanley, W.D.

    1999-01-01

    We use an extensive network of marine high-resolution and conventional industry seismic-reflection data to constrain the location, shallow structure, and displacement rates of the Seattle fault zone and crosscutting high-angle faults in the Puget Lowland of western Washington. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates that the west-trending Seattle fault comprises a broad (4-6 km) zone of three or more south-dipping reverse faults. Quaternary sediment has been folded and faulted along all faults in the zone but is clearly most pronounced along fault A, the northernmost fault, which forms the boundary between the Seattle uplift and Seattle basin. Analysis of growth strata deposited across fault A indicate minimum Quaternary slip rates of about 0.6 mm/yr. Slip rates across the entire zone are estimated to be 0.7-1.1 mm/yr. The Seattle fault is cut into two main segments by an active, north-trending, high-angle, strike-slip fault zone with cumulative dextral displacement of about 2.4 km. Faults in this zone truncate and warp reflections in Tertiary and Quaternary strata and locally coincide with bathymetric lineaments. Cumulative slip rates on these faults may exceed 0.2 mm/yr. Assuming no other crosscutting faults, this north-trending fault zone divides the Seattle fault into 30-40-km-long western and eastern segments. Although this geometry could limit the area ruptured in some Seattle fault earthquakes, a large event ca. A.D. 900 appears to have involved both segments. Regional seismic-hazard assessments must (1) incorporate new information on fault length, geometry, and displacement rates on the Seattle fault, and (2) consider the hazard presented by the previously unrecognized, north-trending fault zone.

  12. Variations in alluvial style of Tertiary units in response to tectonism, Las Monas area, middle Magdalena valley, Colombia

    SciTech Connect

    Jordan, D.W.; Siemers, C.T.

    1989-03-01

    Detailed sedimentologic and petrographic analyses of Tertiary alluvial sandstone outcrops within and east of producing oil fields in the Las Monas area in Colombia, South America, indicate that depositional style changed from fluvial-deltaic to braided streams atop alluvial fans to high-sinuosity meandering streams in response to uplifts in the surrounding areas. Diverse paleocurrent trends in the Tertiary formations in the perimeter area demonstrate that streams flowed northeast and northwest. Streams in the oil field had easterly and southerly components. Source areas contributing sediment were different and reflected uplifts to the west and south of the Las Monas area. Petrographic composition of sandstones that have easterly and southerly paleocurrent trends in the field area contain more feldspar and less polycrystalline strained quartz than sandstones having a northerly trend in the perimeter area. Sandstones in the field area represent an unroofing of a western granitic terrain, possibly in the ancestral Central Cordillera.

  13. Active Fault Characterization in the Urban Area of Vienna

    NASA Astrophysics Data System (ADS)

    Decker, Kurt; Grupe, Sabine; Hintersberger, Esther

    2016-04-01

    The identification of active faults that lie beneath a city is of key importance for seismic hazard assessment. Fault mapping and characterization in built-up areas with strong anthropogenic overprint is, however, a challenging task. Our study of Quaternary faults in the city of Vienna starts from the re-assessment of a borehole database of the municipality containing several tens of thousands of shallow boreholes. Data provide tight constraints on the geometry of Quaternary deposits and highlight several locations with fault-delimited Middle to Late Pleistocene terrace sediments of the Danube River. Additional information is obtained from geological descriptions of historical outcrops which partly date back to about 1900. The latter were found to be particularly valuable by providing unprejudiced descriptions of Quaternary faults, sometimes with stunning detail. The along-strike continuations of some of the identified faults are further imaged by industrial 2D/3D seismic acquired outside the city limits. The interpretation and the assessment of faults identified within the city benefit from a very well constrained tectonic model of the active Vienna Basin fault system which derived from data obtained outside the city limits. This data suggests that the urban faults are part of a system of normal faults compensating fault-normal extension at a releasing bend of the sinistral Vienna Basin Transfer Fault. Slip rates estimated for the faults in the city are in the range of several hundredths of millimetres per year and match the slip rates of normal faults that were trenched outside the city. The lengths/areas of individual faults estimated from maps and seismic reach up to almost 700 km² suggesting that all of the identified faults are capable of producing earthquakes with magnitudes M>6, some with magnitudes up to M~6.7.

  14. Tectonic Maps of the Poles

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These tectonic relief maps of the north (left, view large [540k]) and south (right, view large [411k]) poles are the result of new satellite-based technologies which are being used to analyze tectonic activity in the Earth's crust. These maps, known as Digital Tectonic Activity Maps (DTAMs), synoptically depict the architecture of the Earth's crust including current and past tectonic activity. This is significant because it permits researchers to view broad zones of activity over the entire surface of the Earth, rather than focusing on single boundary features. By looking at these 'big pictures,' scientists can possibly identify regions of activity which were not previously recognized or mapped using traditional methods. For more information, see: DTAM web site Putting Earthquakes in Their Place Images courtesy Brian Montgomery, NASA GSFC; data by Paul Lowman and Jacob Yates, NASA GSFC

  15. Tectonic versus eustatic control on Neogene sedimentation in the Cibao basin of the Dominican Republic: Tectonic dominance near an active plate boundary

    SciTech Connect

    Erikson, J.P. )

    1991-03-01

    Continuous Neogene subsidence, transgression, and brief periods of accelerated subsidence are indicated by the Yaque Group sediments of the Cibao basin of northern Dominican Republic, in which the generally fining-upward sediments are punctuated by two, thick, conglomeratic sequences. Lithologic and paleontologic evidence support continuous subsidence and a tectonic control on sedimentation and is in conflict with an interpretation of one or both of the conglomeratic sequences as being due to a rapid regressive-transgressive cycle and a correlation with a second-order fluctuation (supercycle) on a Vail-type sea-level curve. Subsidence generally outpaced sedimentation, such that water depths almost continuously increased during deposition of all but the uppermost Yaque Group (when the basin shallowed prior to the subaerial exposure), as interpreted from detailed paleontological analyses. The depositional history of the entire {approximately}1 km exposed section and {approximately}5 km subsurface section of the Yaque Group is best explained by a single, continuous, east to west, middle Miocene to earliest Pliocene transgression due to asymmetric basin subsidence. Deposition of the igneous clast-rich conglomerates was probably caused by accelerated basement subsidence at the northern edge of the basin, which oversteepened the depositional slope, led to accelerated transgression of the northern flank of the Central Cordillera, and produced brief pulses of coarse, partially Cordilleran-derived conglomerates. Varying subsidence of the Cibao basin is correlated with episodic uplift and sedimentation in the Cordillera Septentrional.

  16. The 1946 Unimak Tsunami Earthquake Area: revised tectonic structure in reprocessed seismic images and a suspect near field tsunami source

    USGS Publications Warehouse

    Miller, John J.; von Huene, Roland; Ryan, Holly F.

    2014-01-01

    In 1946 at Unimak Pass, Alaska, a tsunami destroyed the lighthouse at Scotch Cap, Unimak Island, took 159 lives on the Hawaiian Islands, damaged island coastal facilities across the south Pacific, and destroyed a hut in Antarctica. The tsunami magnitude of 9.3 is comparable to the magnitude 9.1 tsunami that devastated the Tohoku coast of Japan in 2011. Both causative earthquake epicenters occurred in shallow reaches of the subduction zone. Contractile tectonism along the Alaska margin presumably generated the far-field tsunami by producing a seafloor elevation change. However, the Scotch Cap lighthouse was destroyed by a near-field tsunami that was probably generated by a coeval large undersea landslide, yet bathymetric surveys showed no fresh large landslide scar. We investigated this problem by reprocessing five seismic lines, presented here as high-resolution graphic images, both uninterpreted and interpreted, and available for the reader to download. In addition, the processed seismic data for each line are available for download as seismic industry-standard SEG-Y files. One line, processed through prestack depth migration, crosses a 10 × 15 kilometer and 800-meter-high hill presumed previously to be basement, but that instead is composed of stratified rock superimposed on the slope sediment. This image and multibeam bathymetry illustrate a slide block that could have sourced the 1946 near-field tsunami because it is positioned within a distance determined by the time between earthquake shaking and the tsunami arrival at Scotch Cap and is consistent with the local extent of high runup of 42 meters along the adjacent Alaskan coast. The Unimak/Scotch Cap margin is structurally similar to the 2011 Tohoku tsunamigenic margin where a large landslide at the trench, coeval with the Tohoku earthquake, has been documented. Further study can improve our understanding of tsunami sources along Alaska’s erosional margins.

  17. Active tectonics of North Haji Abad (Hormozgan region) in south of Iran

    NASA Astrophysics Data System (ADS)

    shafiei bafti, amir

    2014-05-01

    Zagros Active Fold -thrust Belt is situated in the northern margin of the Arabian Plat and formed due to shortening, thickening and uplift of tethys sedimentary basin between Arabian and Iranian plates. In this study, the rate of uplift in the northern margin of the Zagros Mountains in southern Iran are examined. The Zagros fault zone in this region is composed of a set faults, including Deragah, Haji Abad, Tezerj and several other faults and also we call these branches from F1 to F8. These segments puts from northwest to the East- Southeast. Based on field surveys and Geological maps, we prepared a structural map from major faults of Zagros fault system for identify faults pattern and estimating of uplift rate movements in Zagros fault. Three methods used to calculation of uplift rate: A: Asymmetry index Accordance with the procedure, in studied area, northeast drainage are longer than of southwest drainage and east minor drainages also longer than the west side drainages, Uplifting in this region is characterized by mentioned asymmetry factor. The amount of this index is AF=71.81. B. Interaction between the faults movements and erosion process We comparison contrast between uplifting movement rates and erosion rates in different parts of studied region by Smf and other indexes. Average amount of Smf=1.1. C. Evaluation of Uplift rate of alluvial terraces was performed by sediment ages and terraces height. We surveyed Quaternary facieses which have ages between 17,000 and 30,000 years old. the rate of uplifting for each fault is follows : Deragah fault and F8 fault between 1.0 to 1.85mm per year and F7, F6, F5, and F4 faults, have a rate Uplifting between 0.6 to 1.0 mm per year and the rate of Uplift for other faults is between 0.04 to 0.06 mm per year. According to our studies, uplift rates in north -east and south-west more than other regions The minimum rate at different stations are about 0.5mm/y to 0.93mm/y and its maximum is 0.88 mm/y to 1.47mm/y.

  18. Upper plate deformation and seismic barrier in front of Nazca subduction zone: The Chololo Fault System and active tectonics along the Coastal Cordillera, southern Peru

    NASA Astrophysics Data System (ADS)

    Audin, Laurence; Lacan, Pierre; Tavera, Hernando; Bondoux, Francis

    2008-11-01

    The South America plate boundary is one of the most active subduction zone. The recent Mw = 8.4 Arequipa 2001 earthquake ruptured the subduction plane toward the south over 400 km and stopped abruptly on the Ilo Peninsula. In this exact region, the subduction seismic crisis induced the reactivation of continental fault systems in the coastal area. We studied the main reactivated fault system that trends perpendicular to the trench by detailed mapping of fault related-geomorphic features. Also, at a longer time scale, a recurrent Quaternary transtensive tectonic activity of the CFS is expressed by offset river gullies and alluvial fans. The presence of such extensional fault systems trending orthogonal to the trench along the Coastal Cordillera in southern Peru is interpreted to reflect a strong coupling between the two plates. In this particular case, stress transfer to the upper plate, at least along the coastal fringe, appears to have induced crustal seismic events that were initiated mainly during and after the 2001 earthquake. The seafloor roughness of the subducting plate is usually thought to be a cause of segmentation along subduction zones. However, after comparing and discussing the role of inherited structures within the upper plate to the subduction zone segmentation in southern Peru, we suggest that the continental structure itself may exert some feedback control on the segmentation of the subduction zone and thus participate to define the rupture pattern of major subduction earthquakes along the southern Peru continental margin.

  19. Spiral tectonics

    NASA Astrophysics Data System (ADS)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  20. Interplay between active and past tectonics in the Hellenic Arc (Greece): Geological and geomorphic evidences from Kythira Island

    NASA Astrophysics Data System (ADS)

    Fernández-Blanco, David; de Gelder, Gino; Delorme, Arthur; Lacassin, Robin; Armijo, Rolando

    2016-04-01

    The Hellenic Arc undergoes the largest convergence velocity and highest seismic activity among Mediterranean subduction systems. The outer-arc high islands of the Hellenic Arc are thus key to understand the mode of deformation of the crust during subduction and the mechanisms behind vertical motions at the front of overriding plates, here and elsewhere. Kythira Island, located between SW Peloponnese and NE Crete, provides an exceptional opportunity to understand the interaction between past and active tectonics in the Hellenic Arc. The recent uplift of the Kythira Island is marked in its landscape as paleosurfaces, marine terraces, abandon valleys and gorges. Together with the sedimentary record of the island and its geologic structures, we attempt to reconstruct its tectonic evolution since the latest Miocene. Here, we present exceptionally detailed geological and geomorphological maps of the Kythira Island based on fieldwork, Pleiades satellite imagery and 2-m resolution DEM, as well as the analyses of marine terraces and river network morphometrics. Pliocene or younger infill sequences rest atop of Palaeocene or older rocks in several marine basins in the island. In the largest marine basin, we found a stratigraphic sequence with a (tilted) continental conglomerate at the base, passing upwards to a disconformal subhorizontal conglomerate, calcarenites and fine sands, and terminating with a marine conglomerate. This marine conglomerate acts as a "cap rock" that marks the topography and shapes the highermost, and most extensive, low-relief surface. Overall, the infill sequence onlaps basement with the exception of the western margin where normal faults partly controlled the deposition of its lower sector. These faults reactivated older Hellenic fold-and-thrust structures, parallel to the subduction trench, and were not active during the maximum marine transgression that led to the deposition of the subhorizontal part of the infill sequence, including the topmost

  1. Petrography and geochemistry of sands from the Chachalacas and Veracruz beach areas, western Gulf of Mexico, Mexico: Constraints on provenance and tectonic setting

    NASA Astrophysics Data System (ADS)

    Armstrong-Altrin, John S.; Nagarajan, Ramasamy; Balaram, Vysetti; Natalhy-Pineda, Olmedo

    2015-12-01

    Compositional and geochemical analyses of sands collected from the Chachalacas (CHA) and Veracruz (VER) beach areas along the western Gulf of Mexico were studied to determine the provenance and tectonic setting of the source region. The modal composition showed that the proportion of quartz (Q) is lower in CHA than in VER sands. The average quartz-feldspar-lithic fragment (QFL) ratios for the CHA and VER sands are Q75F8L17 and Q86F4L10, respectively. The X-ray diffractometer (XRD) and Scanning Electron Microscope equipped with EDAX spectrometer (SEM-EDS) data revealed that the CHA sands were abundant in heavy minerals like magnetite, ilmenite, and zircon. The rare earth element concentration (REE) is higher in CHA than in VER sands, which is due to the concentration of heavy minerals in CHA sands. The weathering indices such as chemical index of alteration (CIA), plagioclase index of alteration, and A-CN-K (A = Al2O3, CN = CaO∗ + Na2O, K = K2O) plot suggested that the intensity of weathering in the source area was low to moderate. The index of chemical variability (ICV) for the CHA (˜1.9-3.0) and VER (˜0.82-1.33) sands indicated that the compositional maturity was higher for the VER sands. The concentrations of Co, Cr, Ni, and V are lower in VER sands than in CHA sands, indicating that the CHA sands were derived from the intermediate source rocks. Provenance modelling revealed that the CHA sands were associated with the mixture of basalt, andesite, dacite, and trachyandesite in the ratio of 5:20:25:50. The VER sands were best matched with a mixture having 75-90% dacite and 25-10% andesite compositions. The provenance difference between the two beach areas suggested that longshore current play a less significant role in mixing and homogenization of sands. The multidimensional tectonic discrimination diagrams revealed rift and collision settings for the VER and CHA beach areas, respectively, which is consistent with the general geology of the study areas.

  2. Characterization of the Monument Hill fault system and implications for the active tectonics of the Red Rock Valley, Southwestern Montana

    NASA Astrophysics Data System (ADS)

    Regalla, Christine A.; Anastasio, David J.; Pazzaglia, Frank J.

    2007-08-01

    New geologic mapping, morphologic fault scarp modeling, and geomorphic metrics in the Red Rock Valley, southwestern Montana, help characterize the Quaternary history of the virtually unstudied Monument Hill fault and tectonics of the youthful and seismically active Red Rock graben. Two generations of Pleistocene surface ruptures are preserved along the Monument Hill fault. Similarity in rupture ages along multiple strands, determined from offset alluvial surfaces and morphologic modeling, suggest earthquake clusters at 22-32 ka and possibly >160 ka. Quaternary activity along the Monument Hill fault is also reflected in elongate drainage basins and channel profiles with anomalously steep reaches coincident with mapped faults. An anticlinal accommodation zone at Kidd accommodates a change in fault polarity between the en echelon Monument Hill and Red Rock faults and a northward decrease in extension within the Red Rock graben. The unique rupture histories of the Monument Hill and Red Rock faults, however, suggest the systems are not seismogenically linked and that the accommodation zone serves as a rupture barrier. The geometry, interconnectivity, and kinematics of faults in the Red Rock Valley may represent a snapshot of the early stages of extension applicable to the evolution of other Northern Basin and Range grabens.

  3. A test of the hypothesis that impact-induced fractures are preferred sites for later tectonic activity

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.; Duxbury, Elizabeth D.

    1987-01-01

    Impact cratering has been an important process in the solar system. The cratering event is generally accompanied by faulting in adjacent terrain. Impact-induced faults are nearly ubiquitous over large areas on the terrestrial planets. The suggestion is made that these fault systems, particularly those associated with the largest impact features are preferred sites for later deformation in response to lithospheric stresses generated by other processes. The evidence is a perceived clustering of orientations of tectonic features either radial or concentric to the crater or basin in question. An opportunity exists to test this suggestion more directly on Earth. The terrestrial continents contain more than 100 known or probable impact craters, with associated geological structures mapped to varying levels of detail. Prime facie evidence for reactivation of crater-induced faults would be the occurrence of earthquakes on these faults in response to the intraplate stress field. Either an alignment of epicenters with mapped fault traces or fault plane solutions indicating slip on a plane approximately coincident with that inferred for a crater-induced fault would be sufficient to demonstrate such an association.

  4. Origin of metabasites from upper tectonic unit of the Lavrion area (SE Attica, Greece): Geochemical implications for dual origin with distinct provenance of blueschist and greenschist's protoliths

    NASA Astrophysics Data System (ADS)

    Baziotis, I.; Mposkos, E.

    2011-10-01

    The Lavrion area forms the westernmost part of the Attic-Cycladic crystalline belt (ACCB) and is built up by two tectonic units metamorphosed at HP/LT conditions. In the Upper Tectonic Unit metabasic rocks occur as greenschists and blueschists. Major and trace elements plotted against Mg# show a systematic increase in TiO 2, Fe 2O 3*, Na 2O, Zr, Y, V, La and Yb and a decrease in Al 2O 3, Ni and Cr with decreasing Mg#. Typically, the blueschists always exhibit a more evolved basaltic composition. The greenschists are characterized by LREE-depleted chondrite-normalized REE patterns and Zr/Nb values that range from 15 to 24. The blueschists are characterized by slightly LREE-enriched chondrite-normalized REE patterns and lower Zr/Nb ratios (6.6-11.3). Both rock types share common geochemical features like flat HFSE patterns or slight positive Nb anomalies with La/Nb < 1. The protoliths of both greenschists and blueschists show that two different suites generated their protoliths and that their magmatic evolution at low pressures has also been different. The observed Zr/Nb vs. Ce/Y ratios span the compositions of greenschists and blueschists out on hyperbolae at an ideal spectrum from intermediate N-MORB to E-MORB. However, the REE patterns of the studied metabasites cannot be explained by fractional crystallization processes alone. We interpret that the protoliths of the Lavrion metabasites support a dual origin; the blueschist's protoliths are comparable to rift-related mildly alkaline basalts whereas the greenschist's protoliths probably formed as typical N-MORB at an oceanic spreading center or in an evolved back-arc basin. A mélange setting with two distinct provenances of the basic protoliths is the proposed genetic model, similar to that envisioned for other parts of the ACCB, e.g. the islands of Syros, Sifnos and Tinos.

  5. Late Paleozoic tectonic evolution of the Central Asian Orogenic Belt: Constraints from multiple arc-basin systems in Altai-Junggar area, NW China

    NASA Astrophysics Data System (ADS)

    Li, D.

    2015-12-01

    In this study, we report results from integrated geological, geophysical and geochemical investigations on the Wulungu Depression of the Junggar Basin to understand the Late Paleozoic continental growth of the Junggar area and its amalgamation history with the Altai terrane, within the broad tectonic evolution of the Altai-Junggar area. Based on seismic and borehole data, the Wulungu Depression can be divided into two NW-trending tectonic units by southward thrust faults. The Suosuoquan Sag is composed of gray basaltic andesite, andesite, tuff, tuffaceous sandstone and tuffite, and the overlying Early Carboniferous volcano-sedimentary sequence with lava gushes and marine sediments from a proximal juvenile provenance, compared to the andesite in the Hongyan High. The SIMS Zircon U-Pb ages for andesites from Late Paleozoic strata indicate that these volcanics in Suosuoquan Sag and Hongyan High erupted at 376.3Ma and 313.4Ma, respectively. Most of the intermediate-mafic volcanic rocks exhibit calc-alkaline affinity, low initial 87Sr/86Sr and positive ɛNd(t) and ɛHf(t) values. Furthermore, these rocks have high Th/Yb and low Ce/Pb and La/Yb ratios as well as variable Ba/Th and Ba/La ratios. These features imply that the rocks were derived from partial melting of a mantle wedge metasomatized by subduction-related components in an island arc setting. The basin filling pattern and the distribution of island arc-type volcanics and their zircon Hf model ages with the eruptive time suggest that the Wulungu Depression represents an island arc-basin system with the development of a Carboniferous retro-arc basin. The gravity and magnetic anomaly data suggest that Altai-Junggar area incorporates three arc-basin belts from north to south: the Karamaili-Luliang-Darbut, Yemaquan-Wulungu, and Dulate-Fuhai-Saur. The recognition of the Wulungu arc-basin system demonstrates that the northern Junggar area is built by amalgamation of multiple Paleozoic linear arcs and accretionary

  6. Active tectonics of the Devils Mountain Fault and related structures, northern Puget Lowland and eastern Strait of Juan de Fuca region, Pacific Northwest

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dadisman, Shawn V.; Mosher, David C.; Blakely, Richard J.; Childs, Jonathan R.

    2001-01-01

    Information from marine high-resolution and conventional seismic-reflection surveys, aeromagnetic mapping, coastal exposures of Pleistocene strata, and lithologic logs of water wells is used to assess the active tectonics of the northern Puget Lowland and eastern Strait of Juan de Fuca region of the Pacific Northwest. These data indicate that the Devils Mountain Fault and the newly recognized Strawberry Point and Utsalady Point faults are active structures and represent potential earthquake sources.

  7. Teaching Plate Tectonic Concepts using GeoMapApp Learning Activities

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.; Kluge, S.

    2012-12-01

    GeoMapApp Learning Activities ( http://serc.carleton.edu/geomapapp/collection.html ) can help educators to expose undergraduate students to a range of earth science concepts using high-quality data sets in an easy-to-use map-based interface called GeoMapApp. GeoMapApp Learning Activities require students to interact with and analyse research-quality geoscience data as a means to explore and enhance their understanding of underlying content and concepts. Each activity is freely available through the SERC-Carleton web site and offers step-by-step student instructions and answer sheets. Also provided are annotated educator versions of the worksheets that include teaching tips, additional content and suggestions for further work. The activities can be used "off-the-shelf". Or, since the educator may require flexibility to tailor the activities, the documents are provided in Word format for easy modification. Examples of activities include one on the concept of seafloor spreading that requires students to analyse global seafloor crustal age data to calculate spreading rates in different ocean basins. Another activity has students explore hot spots using radiometric age dating of rocks along the Hawaiian-Emperor seamount chain. A third focusses upon the interactive use of contours and profiles to help students visualise 3-D topography on 2-D computer screens. A fourth activity provides a study of mass wasting as revealed through geomorphological evidence. The step-by-step instructions and guided inquiry approach reduce the need for teacher intervention whilst boosting the time that students can spend on productive exploration and learning. The activities can be used, for example, in a classroom lab with the educator present and as self-paced assignments in an out-of-class setting. GeoMapApp Learning Activities are funded through the NSF GeoEd program and are aimed at students in the introductory undergraduate, community college and high school levels. The activities are

  8. Buried paleo-sedimentary basins in the north-eastern Black Sea-Azov Sea area and tectonic implications (DOBRE-2)

    NASA Astrophysics Data System (ADS)

    Starostenko, Vitaly; Stephenson, Randell; Janik, Tomasz; Tolkunov, Anatoly

    2014-05-01

    A number of independent but inter-related projects carried out under the auspices of various national and international programmes in Ukraine including DARIUS were aimed at imaging the upper lithosphere, crustal and sedimentary basin architecture in the north-eastern Black Sea, southern Crimea and Kerch peninsulas and the Azov Sea. This region marks the transition from relatively undisturbed Precambrian European cratonic crust and lithosphere north of the Azov Sea to areas of significant Phanerozoic tectonics and basin development, in both extensional as well as compressional environments, to the south, including the eastern Black Sea rift, which is the main sedimentary basin of the study area. The wide-angle reflection and refraction (WARR) profile DOBRE-2, a Ukrainian national project with international participation (see below), overlapping some 115 km of the southern end of the DOBREfraction'99 profile (that crosses the intracratonic Donbas Foldbelt) in the north and running to the eastern Black Sea basin in the south, utilised on- and offshore recording and energy sources. It maps crustal velocity structure across the craton margin and documents, among other things, that the Moho deepens from 40 km to ~47 km to the southwest below the Azov Sea and Crimean-Caucasus deformed zone. A regional CDP seismic profile coincident with DOBRE-2, crossing the Azov Sea, Kerch Peninsula and the north-eastern Black Sea southwest to the Ukraine-Turkey border, acquired by Ukrgeofisika (the Ukrainian national geophysical company) reveals in its inferred structural relationships the ages of Cretaceous and younger extensional and subsequent basin inversion tectonic events as well as the 2D geometry of basement displacement associated with post mid-Eocene inversion. A direct comparison of the results of the WARR velocity model and the near-vertical reflection structural image has been made by converting the former into the time domain. The results dramatically demonstrate that

  9. Damping scaling factors for elastic response spectra for shallow crustal earthquakes in active tectonic regions: "average" horizontal component

    USGS Publications Warehouse

    Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Abrahamson, Norman; Campbell, Kenneth; Silva, Walter

    2014-01-01

    Ground motion prediction equations (GMPEs) for elastic response spectra are typically developed at a 5% viscous damping ratio. In reality, however, structural and nonstructural systems can have other damping ratios. This paper develops a new model for a damping scaling factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE for damping ratios between 0.5% to 30%. The model is developed based on empirical data from worldwide shallow crustal earthquakes in active tectonic regions. Dependencies of the DSF on potential predictor variables, such as the damping ratio, spectral period, ground motion duration, moment magnitude, source-to-site distance, and site conditions, are examined. The strong influence of duration is captured by the inclusion of both magnitude and distance in the DSF model. Site conditions show weak influence on the DSF. The proposed damping scaling model provides functional forms for the median and logarithmic standard deviation of DSF, and is developed for both RotD50 and GMRotI50 horizontal components. A follow-up paper develops a DSF model for vertical ground motion.

  10. A subdued topography among the high relief, tectonic-active island ---registered middle to late Pleistocene climatic changes in Taiwan

    NASA Astrophysics Data System (ADS)

    Liew, P.; Chen, B.

    2003-12-01

    The island of Taiwan is geographically in the frontal zone of the Asian monsoon region, and is geologically located in the collision boundary between the Philippine Sea plate and the Eurasian plate. A Holocene uplifting rate of up to 10mm/yr in the eastern coast has been documented in this high relief mountainous island, and active folds and thrusts are common. When tracing the rivers backward to the mountain, one often encounters a subdued topography, covered by primary lateritic soil, above the higher river terrace and below the rugged mountains, and is referred to as lateritic highland (LH) by a previous author. Studies in paleoclimatology and geomorphology enable us to refine the possible age and origin of this remarkable topography. The penultimate glacial-interglacial cycle and the last interglacial period should be the major interval for the development of lateritic highland. LH may be looked upon as a reference surface for studying the dynamic evolution of the tectonic landscape of Taiwan. It shows that the lower uplifting rate is the most important factor for the preservation of the LH topography in this island. Based on the morphology of LH, different deformation styles are recognized in north and south Chiayi (near tropic of cancer), in western Taiwan. To the north, platforms originating from piedmont LH are well developed, whereas to the south, platforms and piedmont LH are hardly visible. This contrast is probably due to a lithological variance between them.

  11. Late Pleistocene to Holocene sedimentation and hydrocarbon seeps on the continental shelf of a steep, tectonically active margin, southern California, USA

    USGS Publications Warehouse

    Draut, Amy E.; Hart, Patrick E.; Lorenson, T.D.; Ryan, Holly F.; Wong, Florence L.; Sliter, Ray W.; Conrad, James E.

    2009-01-01

    Small, steep, uplifting coastal watersheds are prolific sediment producers that contribute significantly to the global marine sediment budget. This study illustrates how sedimentation evolves in one such system where the continental shelf is largely sediment-starved, with most terrestrial sediment bypassing the shelf in favor of deposition in deeper basins. The Santa Barbara-Ventura coast of southern California, USA, is considered a classic area for the study of active tectonics and of Tertiary and Quaternary climatic evolution, interpretations of which depend upon an understanding of sedimentation patterns. High-resolution seismic-reflection data over >570 km2 of this shelf show that sediment production is concentrated in a few drainage basins, with the Ventura and Santa Clara River deltas containing most of the upper Pleistocene to Holocene sediment on the shelf. Away from those deltas, the major factor controlling shelf sedimentation is the interaction of wave energy with coastline geometry. Depocenters containing sediment 5-20 m thick exist opposite broad coastal embayments, whereas relict material (bedrock below a regional unconformity) is exposed at the sea floor in areas of the shelf opposite coastal headlands. Locally, natural hydrocarbon seeps interact with sediment deposition either to produce elevated tar-and-sediment mounds or as gas plumes that hinder sediment settling. As much as 80% of fluvial sediment delivered by the Ventura and Santa Clara Rivers is transported off the shelf (some into the Santa Barbara Basin and some into the Santa Monica Basin via Hueneme Canyon), leaving a shelf with relatively little recent sediment accumulation. Understanding factors that control large-scale sediment dispersal along a rapidly uplifting coast that produces substantial quantities of sediment has implications for interpreting the ancient stratigraphic record of active and transform continental margins, and for inferring the distribution of hydrocarbon resources

  12. Slip sense inversion on active strike-slip faults in southwest Japan and its implications for Cenozoic tectonic evolution

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2004-05-01

    Analyses of deflected river channels, offset of basement rocks, and fault rock structures reveal that slip sense inversion occurred on major active strike-slip faults in southwest Japan such as the Yamasaki and Mitoke fault zones and the Median Tectonic Line (MTL). Along the Yamasaki and Mitoke fault zones, small-size rivers cutting shallowly mountain slopes and Quaternary terraces have been deflected sinistrally, whereas large-size rivers which deeply incised into the Mio-Pliocene elevated peneplains show no systematically sinistral offset or complicated hairpin-shaped deflection. When the sinistral offsets accumulated on the small-size rivers are restored, the large-size rivers show residual dextral deflections. This dextral offset sense is consistent with that recorded in the pre-Cenozoic basement rocks. S-C fabrics of fault gouge and breccia zone developed in the active fault zones show sinistral shear sense compatible with earthquake focal mechanisms, whereas those of the foliated cataclasite indicate a dextral shear sense. These observations show that the sinistral strike-slip shear fabrics were overprinted on dextral ones which formed during a previous deformation phase. Similar topographic and geologic features are observed along the MTL in the central-eastern part of the Kii Peninsula. Based on these geomorphological and geological data, we infer that the slip sense inversion occurred in the period between the late Tertiary and mid-Quaternary period. This strike-slip inversion might result from the plate rearrangement consequent to the mid-Miocene Japan Sea opening event. This multidisciplinary study gives insight into how active strike-slip fault might evolves with time.

  13. Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

    USGS Publications Warehouse

    Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

    2010-01-01

    This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

  14. Remote sensing and tectonic analysis of active volcanoes in continental arcs

    NASA Astrophysics Data System (ADS)

    Wessels, Rick Lee

    Variations in arc volcano spatial distribution and morphology are influenced by the crustal structure beneath the arc. In Colombia and Ecuador, most of the active volcanoes lie on or near regional arc-parallel fault zones, and many of the major volcanoes are aligned or elongated parallel to the faults. Two dominant volcano-fault geometry patterns exist: (1) From north to south, the orientation of the fractures and volcano-shapes changes along the arc from primarily north-northwest trending to east-northeast trending; and (2) From west to east, the fault and volcano alignment patterns vary from north-northwest trends at the outer edges of the arc to east-northeast trending in the middle of the arc. The fault and volcano orientation patterns are related to the age and type of crust being faulted during oblique subduction. The regionally active strike-slip faults in the Northern Andes and other arcs provide long-lasting paths for magma ascent that penetrate much deeper through the lithosphere than the secondary features. Local zones of extension and pre-existing fractures in the last several kilometers of lithosphere provide the plumbing that diverts magma slightly away from the primary linear volcanic front. The dissertation also describes a technique for merging multiple remote sensing data sets over the extremely rough terrain of silicic volcanoes. The major focus of this work was on overcoming coregistration errors from geometric distortion induced by local topography. The geometric distortion was compensated for by first creating an accurate base image with a combination of global positioning system (GPS) ground control, high resolution digital elevation models (DEM), and orthorectified aerial photographs. The individual sensor data were then rectified to the new reference base using triangulation geocoding. The final multi-layered, geocoded product is being used to enhance an existing thermal infrared technique for mapping complex textural patterns in silicic

  15. Cenozoic Tectonic Activity of the "Passive" North America Margin: Evidence for Cenozoic Activity on Mesozoic or Paleozoic Faults

    NASA Astrophysics Data System (ADS)

    Nedorub, O. I.; Knapp, C. C.

    2012-12-01

    The tectonic history of the Eastern North American Margin (ENAM) incorporates two cycles of continental assembly, multiple pulses of orogeny, rifting, and post-rift geodynamic evolution. This is reflected in the heterogeneous lithosphere of the ENAM which contains fault structures originated in Paleozoic to Mesozoic eras. The South Georgia Rift basin is probably the largest Mesozoic graben within its boundaries that is associated with the breakup of Pangea. It is composed of smaller sub-basins which appear to be bounded by high-angle normal faults, some of which may have been inverted in late Cretaceous and Cenozoic eras. Paleozoic structures may have been reactivated in Cenozoic time as well. The ENAM is characterized by N-NE maximum horizontal compressive stress direction. This maximum compressional stress field is sub-parallel to the strike of the Atlantic Coast province fault systems. Camden, Augusta, Allendale, and Pen Branch faults are four of the many such reactivated faults along the southern part of ENAM. These faults are now buried under the 0-400 m of loosely consolidated Cretaceous and Cenozoic age sediments and thus are either only partially mapped or currently not recognized. Some of the objectives of this study are to map the subsurface expression and geometry of these faults and to investigate the post Cretaceous deformation and possible causes of fault reactivation on a passive margin. This study employs an integrated geophysical approach to investigate the upper 200 m of identified locations of the above mentioned faults. 2-D high-resolution shallow seismic reflection and refraction methods, gravity surveys, GPR, 2-D electrical resistivity and well data are used for analyses and interpretation. Preliminary results suggest that Camden fault shows signs of Cenozoic reactivation through an approximately 30 m offset NW side up mainly along a steeply dipping fault zone in the basal contact of Coastal Plain sediments with the Carolina Piedmont. Drill

  16. Zircon U-Pb age, Hf isotope and geochemistry of Carboniferous intrusions from the Langshan area, Inner Mongolia: Petrogenesis and tectonic implications

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zhang, Da; Xiong, Guangqiang; Zhao, Hongtao; Di, Yongjun; Wang, Zhong; Zhou, Zhiguang

    2016-04-01

    Late Paleozoic was a critical period for the tectonic evolution of the northern margin of the Alxa-North China craton, but the evolutionary history is not well constrained. The Carboniferous intrusions in the Langshan area in the western part of the northern margin of the Alxa-North China craton are mainly composed of tonalite, quartz diorite, olivine gabbro and pyroxene peridotite. Zircon LA-ICP-MS U-Pb dating indicates that the Langshan Carboniferous intrusions were emplaced at ca. 338-324 Ma. The quartz diorites are characterized by high amounts of compatible trace elements (Cr, Ni and V) and high Mg# values, which may suggest a significant mantle source. The positive Pb and negative Nb-Ta-Ti anomalies, the variable εHf(t) (-6.9 to 2.0) values and the old Hf model ages (1218-1783 Ma) imply some involvement of ancient continental materials in its petrogenesis. The tonalite has relatively high Sr/Y ratios, low Mg#, Yb and Y contents, features of adakite-like rocks, negative εHf(t) values (-9.8 to -0.1) and older Hf model ages (1344-1953 Ma), which suggest significant involvement of ancient crust materials and mantle-derived basaltic component in its petrogenesis. The high Mg# values, high Cr and Ni contents, and low Zr and Hf contents of the mafic-ultramafic rocks show evidence of a mantle source, and the relatively low zircon εHf(t) values (-5.9 to 3.2) might point to an enriched mantle. The trace element characteristics indicate the influence of subducted sediments and slab-derived fluids. In the tectonic discrimination diagrams, all the rocks plot in subduction-related environment, such as volcanic arc and continental arc. Considering the regional geology, we suggest that the Carboniferous intrusions in the Langshan area were likely emplaced during the late stage of the southward subduction of the Paleo-Asian Ocean plate, which formed a continental arc along the northern margin of the Alxa-North China craton.

  17. Tectonics of the central Andes

    NASA Technical Reports Server (NTRS)

    Bloom, Arthur L.; Isacks, Bryan L.; Fielding, Eric J.; Fox, Andrew N.; Gubbels, Timothy L.

    1989-01-01

    Acquisition of nearly complete coverage of Thematic Mapper data for the central Andes between about 15 to 34 degrees S has stimulated a comprehensive and unprecedented study of the interaction of tectonics and climate in a young and actively developing major continental mountain belt. The current state of the synoptic mapping of key physiographic, tectonic, and climatic indicators of the dynamics of the mountain/climate system are briefly reviewed.

  18. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    SciTech Connect

    Ry, Rexha Verdhora; Nugraha, Andri Dian

    2015-04-24

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location.

  19. Active tectonics in the NW-German Basin: Evidence from correlations between the modern landscape and deep geological structures (Lower Saxony, river Hunte)

    NASA Astrophysics Data System (ADS)

    Szeder, T.; Sirocko, F.

    2003-04-01

    The catchment basin of the river Hunte (NW-German Basin, Lower Saxony) was studied on a mesoscale (length of ˜90 km) to investigate if tectonic movements in the upper crust influence modern landscape formation. Crustal movements led to upwarping of the Lower Weichselian Terrace above the transition zone of a major crustal boundery of the NW-German Basin (Lower Saxony Basin/Pompeckj Block) with an average vertical velocity of about 0,5 mm/a over the last 12 ka. The Lower Weichselian Terrace and the Hunte catchment basin are narrowest at the same position. Even the Holocene Alluvial Plain is affected by active tectonics. The Holocene Alluvial Plain is narrower and shows a negative gradient directly above a deep seated Permian salt pillow which can be traced over a vertical distance of about 4000 m as an anticline structure to the uppermost Tertiary (100 m b.s.l.). The spatial similarity of fluvial anomalies with anomalies of the geological subground indicates that crustal movements still exercise control on fluvial dynamics and are coupled to the geological predesign. Basin subsidence is thought to have triggered primarily the aggradation of the Lower Weichselian Terrace, because there is an accordance between the mean recent velocity of basin subsidence (˜-0,21 mm/a), calculated from repeated geodetic fine levelling and the mean sedimentation rate of the Lower Weichselian Terrace (˜0,2--0,4 mm/a). In addition, sedimentation rates of the Lower Weichselian Terrace were nearly constant over a time span of about 35 ka (˜47--12 ka BP). During these times the climate has changed rapidly over Northern Europe (Dansgaard-Oeschger Cycles) which affected river morphology, hydrology and sediment supply. However, the observation that no change of the mean sedimentation rate is observable indicates a long term subsiding tendency which enables accumulation of longer fluvial sequences independent of short scale climatic fluctuations. Most likely northward tilting of the NW

  20. Natural trace element enrichment in fishes from a volcanic and tectonically active region (Azores archipelago)

    NASA Astrophysics Data System (ADS)

    Raimundo, Joana; Vale, Carlos; Caetano, Miguel; Giacomello, Eva; Anes, Bárbara; Menezes, Gui M.

    2013-12-01

    Seamounts, in general, are thought to support high biodiversity and special biological communities. They have been targeted by commercial fishing for demersal and pelagic fish species due to the occurrence of large aggregations in mid- and deep-water. Specimens of Phycis phycis, Helicolenus dactylopterus, Pontinus kuhlii, Beryx splendens, Beryx decadactylus, Etmopterus pusillus, Mora moro, Pagellus bogaraveo, Deania profundorum, Scomber colias and Trachurus picturatus were collected at the Condor seamount and on the slopes of Faial and Pico islands of Azores archipelago. Concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd and Pb were determined in muscle and liver of each individual. Values of the 11 trace elements in the two tissues of the benthopelagic and benthic specimens, from the two surveyed areas, presented a significant inter-specific variation. In general, levels were lower in muscle than in liver, and negative relations between weight and Co, Mn, Zn, As, Cd and Pb concentrations in muscle and liver of three species were found. Pagellus bogaraveo, S. colias and T. picturatus presented enhanced elemental concentrations in liver, particularly of Cd. The extremely high storage of this potentially toxic element suggests a response to high uptake of Cd and the existence of an additional natural source of Cd to the environment.

  1. Did tectonic activity stimulate oligo-miocene speciation in the Indo-West Pacific?

    PubMed

    Williams, Suzanne T; Duda, Thomas F

    2008-07-01

    Analyses of molecular phylogenies of three unrelated tropical marine gastropod genera, Turbo, Echinolittorina, and Conus, reveal an increase in the rate of cladogenesis of some Indo-West Pacific (IWP) clades beginning in the Late Oligocene or Early Miocene between 23.7 and 21.0 million years ago. In all three genera, clades with an increased rate of diversification reach a maximum of diversity, in terms of species richness, in the central IWP. Congruence in both the geographical location and the narrow interval of timing suggests a common cause. The collision of the Australia and New Guinea plate with the southeast extremity of the Eurasian plate approximately 25 Mya resulted in geological changes to the central IWP, including an increase in shallow-water areas and length of coastline, and the creation of a mosaic of distinct habitats. This was followed by a period of rapid diversification of zooxanthellate corals between 20 and 25 Mya. The findings reported here provide the first molecular evidence from multiple groups that part of the present-day diversity of shallow-water gastropods in the IWP arose from a rapid pulse of speciation when new habitats became available in the Late Oligocene to Early Miocene. After the new habitats were filled, the rate of speciation likely decreased and this combined with high levels of extinction (in some groups), resulted in a slow down in the rate of diversification in the genera examined.

  2. Did tectonic activity stimulate oligo-miocene speciation in the Indo-West Pacific?

    PubMed

    Williams, Suzanne T; Duda, Thomas F

    2008-07-01

    Analyses of molecular phylogenies of three unrelated tropical marine gastropod genera, Turbo, Echinolittorina, and Conus, reveal an increase in the rate of cladogenesis of some Indo-West Pacific (IWP) clades beginning in the Late Oligocene or Early Miocene between 23.7 and 21.0 million years ago. In all three genera, clades with an increased rate of diversification reach a maximum of diversity, in terms of species richness, in the central IWP. Congruence in both the geographical location and the narrow interval of timing suggests a common cause. The collision of the Australia and New Guinea plate with the southeast extremity of the Eurasian plate approximately 25 Mya resulted in geological changes to the central IWP, including an increase in shallow-water areas and length of coastline, and the creation of a mosaic of distinct habitats. This was followed by a period of rapid diversification of zooxanthellate corals between 20 and 25 Mya. The findings reported here provide the first molecular evidence from multiple groups that part of the present-day diversity of shallow-water gastropods in the IWP arose from a rapid pulse of speciation when new habitats became available in the Late Oligocene to Early Miocene. After the new habitats were filled, the rate of speciation likely decreased and this combined with high levels of extinction (in some groups), resulted in a slow down in the rate of diversification in the genera examined. PMID:18410535

  3. Linking Europa’s Plume Activity to Tides, Tectonics, and Liquid Water

    NASA Astrophysics Data System (ADS)

    Rhoden, Alyssa R.; Hurford, Terry; Roth, Lorenz; Retherford, Kurt

    2014-11-01

    Much of the geologic activity preserved on Europa’s icy surface has been attributed to tidal deformation, mainly due to Europa’s eccentric orbit. Although the surface is geologically young, evidence of ongoing tidally-driven processes has been lacking. However, a recent observation of water vapor near Europa’s south pole suggests that it may be geologically active. Non-detections in previous and follow-up observations indicate a temporal variation in plume visibility and suggests a relationship to Europa’s tidal cycle. Similarly, the Cassini spacecraft has observed plumes emanating from the south pole of Saturn’s moon, Enceladus, and variability in the intensity of eruptions has been linked to its tidal cycle. The inference that a similar mechanism controls plumes at both Europa and Enceladus motivates further analysis of Europa’s plume behavior and the relationship between plumes, tides, and liquid water on these two satellites.We determine the locations and orientations of hypothetical tidally-driven fractures that best match the temporal variability of the plumes observed at Europa. Specifically, we identify model faults that are in tension at the time in Europa’s orbit when a plume was detected and in compression at times when the plume was not detected. We find that tidal stress driven solely by eccentricity is incompatible with the observations unless additional mechanisms are controlling the eruption timing or restricting the longevity of the plumes. In contrast, the addition of obliquity tides, and corresponding precession of the spin pole, can generate a number of model faults that are consistent with the pattern of plume detections. The locations and orientations of the model faults are robust across a broad range of precession rates and spin pole directions. Analysis of the stress variations across model faults suggests that the plumes would be best observed earlier in Europa’s orbit. Our results indicate that Europa’s plumes, if

  4. Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front

    USGS Publications Warehouse

    Sohn, M.F.; Mahan, S.A.; Knott, J.R.; Bowman, D.D.

    2007-01-01

    Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

  5. Volcano-tectonic structures, gravity and helium in geothermal areas of Tuscany and Latium (Vulsini volcanic district), Italy

    USGS Publications Warehouse

    Di, Filippo M.; Lombardi, S.; Nappi, G.; Reimer, G.M.; Renzulli, A.; Toro, B.

    1999-01-01

    Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.

  6. Active Deformation in the Zagros-Makran Transition Zone Inferred From GPS, Tectonic and Seismological Measurements

    NASA Astrophysics Data System (ADS)

    Bayer, R.; Shabanian, E.; Regard, V.; Yaminifard, F.; Vernant, P.; Nilforoushan, F.; Abbassi, M.; Chery, J.; Tatar, M.; Doerflinger, E.; Peyret, M.; Daignières, M.; Bellier, O.; Hatzfeld, D.; Mokhtari, M.

    2002-12-01

    The present-day N-S convergence between the Arabian and the Eurasian plates is accommodated in Southern Iran along the Zagros fold and thrust belt (with a shortening of ~8 mm/yr)and by the subduction of the Oman oceanic lithosphere beneath the Makran (with a rate of 18mm/yr). The Bandar Abbas-Strait of Hormuz zone is considered as a transition between the Zagros continental collision and the Makran oceanic subduction. In this area, the strain is mainly accommodated along the NNW-SSE trending reverse right lateral Minab-Zendan-Palami faults and along the N-S trending faults of Sarduiyeh, Jiroft and Sabzevaran. We used GPS network measurements (carried out in 2000 and 2002) to better understand how the deformation is distributed between between the Zagros continental collision and the Makran oceanic subduction. The analysis of the velocities (together with the measurements of the global network of Iran) leads to the following conclusions : - The rate of shortening in the Eastern Zagros is < 8mm/yr. It is < 5 mm/yr between the coast and the Main Zagros Thrust. - The horizontal residual velocities of the coastal sites in Zagros relative to Musandan are < 3mm/yr, evidencing for a small deformation in the Persian Gulf. - Across the Minab-Zendan-Palami faults system GPS measurements are consistent with a N-S trending reverse right lateral motion at rate of ~ 10 mm/yr. - West of the Lut block at the latitude of Khanuj, the N-S trending Sarduiyeh-Jiroft-Sabzevaran fault system is characterized by a 2 mm/yr right strike slip motion. Local seismicity is located at an unusual depth down to 35 km. Little is associated with the Minab-Zendan-Palami faults strike slip faults. They rather suggest that they are associated with a complex transition between the Zagros collision and the Makran subduction. Times delays also suggest a large heterogeneity in the crust across the fault system. These measurements support the model that the convergence from the collision to the subduction is

  7. Episodic Cenozoic volcanism and tectonism in the Andes of Peru

    USGS Publications Warehouse

    Noble, D.C.; McKee, E.H.; Farrar, E.; Petersen, U.

    1974-01-01

    Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise. ?? 1974.

  8. Geologic and tectonic setting of the epicentral area of the Loma Prieta earthquake, Santa Cruz County, California

    SciTech Connect

    Wagner, D.L.

    1990-11-01

    Although shaking from the magnitude 7.1 October 17, 1989 Loma Prieta quake lasted only about 15 seconds, the temblor resulted in 67 deaths, more than 3,500 people injured, and property damage estimated at $7.5 billion, it was felt over an area of about 400,000 square miles and caused the biggest dollar loss of any natural disaster in US history. The following article was originally published in the Division of Mines and Geology Special Publication 104 and describes the regional geology of this catastrophic quake. Such detailed investigations of earthquake processes aid in our understanding of how, where - and hopefully - when they will happen in the future.

  9. Gravity Data from the Teboursouk Area ("Diapirs Zone", Northern Tunisia): Characterization of Deep Structures and Updated Tectonic Pattern

    NASA Astrophysics Data System (ADS)

    Hachani, Fatma; Balti, Hadhemi; Kadri, Ali; Gasmi, Mohamed

    2016-04-01

    Located between eastern segments of the Atlas and Tell-Rif orogenic belts, the "Dome zone" of northern Tunisia is characterized by the juxtaposition of various structures that mainly controlled the long geodynamic history of this part of the south-Tethyan Margin. To better understand the organization and deep extension of these structures, gravity data from the Teboursouk key area are proposed. These data include the plotting of Bouguer anomaly map and related parameters such as vertical and horizontal gradients, upward continuation and Euler solution. Compared to geological and structural maps available, they allow the identification of new deep structures and greater precision regarding the characteristics and organization of known ones; consequently, an updated structural pattern is proposed.

  10. Reliability of calculation of the lithosphere deformations in tectonically stable area of Poland based on the GPS measurements

    NASA Astrophysics Data System (ADS)

    Araszkiewicz, Andrzej; Jarosiński, Marek

    2013-04-01

    In this research we aimed to check if the GPS observations can be used for calculation of a reliable deformation pattern of the intracontinental lithosphere in seismically inactive areas, such as territory of Poland. For this purpose we have used data mainly from the ASG-EUPOS permanent network and the solutions developed by the MUT CAG team (Military University of Technology: Centre of Applied Geomatics). From the 128 analyzed stations almost 100 are mounted on buildings. Daily observations were processed in the Bernese 5.0 software and next the weekly solutions were used to determine the station velocities expressed in ETRF2000. The strain rates were determined for almost 200 triangles with GPS stations in their corners plotted used Delaunay triangulation. The obtained scattered directions of deformations and highly changeable values of strain rates point to insufficient antennas' stabilization as for geodynamical studies. In order to depict badly stabilized stations we carried out a benchmark test to show what might be the effect of one station drift on deformations in contacting triangles. Based on the benchmark results, from our network we have eliminated the stations which showed deformation pattern characteristic for instable station. After several rounds of strain rate calculations and eliminations of dubious points we have reduced the number of stations down to 60. The refined network revealed more consistent deformation pattern across Poland. Deformations compared with the recent stress field of the study area disclosed good correlation in some places and significant discrepancies in the others, which will be the subject of future research.

  11. Microearthquake activity around Kueishantao island, offshore northeastern Taiwan: Insights into the volcano-tectonic interactions at the tip of the southern Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Konstantinou, K. I.; Pan, C.-Y.; Lin, C.-H.

    2013-05-01

    Kueishantao is a volcanic island located offshore the northeastern coast of Taiwan and lies at the tip of the southern Okinawa Trough which is the back-arc basin of the Ryukyu subduction zone. Its last eruption occurred during the Holocene (~ 7 ka), hence Kueishantao can be considered as an active volcano. In an effort to better understand how magmatic processes may interact with the regional tectonics, a seismic network was installed in the area during early January 2008. This network consisted of 16 three-component seismometers located both on Kueishantao and the coast of northeastern Taiwan. One year of data was analyzed yielding 425 earthquakes whose P and S arrival times were manually picked and each event was located using a nonlinear probabilistic location method. In order to improve the location accuracy, the minimum 1-D velocity model for this dataset was derived and all earthquakes were relocated using this model. The results show a tight cluster of events near Kueishantao while the remaining earthquakes are scattered between the island and mainland Taiwan. The majority of hypocentral depths range between 2.5 and 10 km where the former depth coincides with the bottom of the shallow sedimentary layer and the latter with the ductile lower crust. Waveforms of the three largest events were also inverted for the determination of their deviatoric and full moment tensor. No statistically significant isotropic component was found, while two of the events can be explained by a double-couple source. The third event exhibited a low frequency content (< 10 Hz) and a large non-double-couple component suggesting fluid involvement at its source. A stress inversion of all available focal mechanisms in the area shows that fluid circulation in the upper crust generates a local stress field around Kueishantao facilitating the opening of cracks along the NW-SE direction of regional extension.

  12. Deep reaching versus vertically restricted Quaternary normal faults: Implications on seismic potential assessment in tectonically active regions: Lessons from the middle Aterno valley fault system, central Italy

    NASA Astrophysics Data System (ADS)

    Falcucci, E.; Gori, S.; Moro, M.; Fubelli, G.; Saroli, M.; Chiarabba, C.; Galadini, F.

    2015-05-01

    We investigate the Middle Aterno Valley fault system (MAVF), a poorly investigated seismic gap in the central Apennines, adjacent to the 2009 L'Aquila earthquake epicentral area. Geological and paleoseismological analyses revealed that the MAVF evolved through hanging wall splay nucleation, its main segment moving at 0.23-0.34 mm/year since the Middle Pleistocene; the penultimate activation event occurred between 5388-5310 B.C. and 1934-1744 B.C., the last event after 2036-1768 B.C. and just before 1st-2nd century AD. These data define hard linkage (sensu Walsh and Watterson, 1991; Peacock et al., 2000; Walsh et al., 2003, and references therein) with the contiguous Subequana Valley fault segment, able to rupture in large magnitude earthquakes (up to 6.8), that did not rupture since about two millennia. By the joint analysis of geological observations and seismological data acquired during to the 2009 seismic sequence, we derive a picture of the complex structural framework of the area comprised between the MAVF, the Paganica fault (the 2009 earthquake causative fault) and the Gran Sasso Range. This sector is affected by a dense array of few-km long, closely and regularly spaced Quaternary normal fault strands, that are considered as branches of the MAVF northern segment. Our analysis reveals that these structures are downdip confined by a decollement represented by to the presently inactive thrust sheet above the Gran Sasso front limiting their seismogenic potential. Our study highlights the advantage of combining Quaternary geological field analysis with high resolution seismological data to fully unravel the structural setting of regions where subsequent tectonic phases took place and where structural interference plays a key role in influencing the seismotectonic context; this has also inevitably implications for accurately assessing seismic hazard of such structurally complex regions.

  13. Active Tectonics along the Carboneras Fault (SE Iberian Margin): Onshore-Offshore Paleoseismological Approach

    NASA Astrophysics Data System (ADS)

    Moreno, X.; Masana, E.; Gràcia, E.; Pallàs, R.; Santanach, P.; Dañobeitia, J. J.; Party, I.

    2006-12-01

    The southern margin of the Iberian Peninsula hosts the convergent boundary between the European and African Plates. At the eastern Betic Cordillera, the Neogene and Quaternary shortening has mainly been absorbed by left-lateral strike-slip faults, which in the Iberian Peninsula is represented by the Eastern Betics Shear Zone (EBSZ). One of the longest structures in the EBSZ is the Carboneras Fault, with almost 50 km onshore and more than 100 km offshore. The low record seismicity along its trace, suggest either non seismic behaviour or long recurrence intervals (104 years). The aim of this work is an integrated onshore-offshore neotectonic and paleoseismological study of the Carboneras Fault Zone to characterize its seismic potential. The onshore study was made through regional geological and geomorphological analysis, geophysical prospecting, microtopography, trenching, and dating (14 C, U/Th, TL). Onshore macro and microstructures as beheaded and offset alluvial fans and S-C microstructures in the fault zone reveals a Quaternary left-lateral strike-slip motion combined with a vertical component along the fault. Trenching reveals this fault is seismogenic, with at least four late Quaternary events. The oldest occurred between 54.9 and 32.2 ka BP, the second one between 40.9 and 27.1 ka BP, and the two most recent events occurred between 30.8 and 0.875 ka BP. The thickness of the colluvial wedges suggest a Mw=7 for the first and Mw=6.6 for the second event. The mean recurrence rate is 14 ka, and the minimum elapsed time is 875 years. The offshore portion, studied by high-resolution marine geophysical methods, shows very similar strike-slip structures. The marine paleoseismic data will be integrated with the onland results in order to accurately determine the recent activity and seismic parameters of the entire Carboneras Fault.

  14. Active Tectonics of the Lower Tagus Valley Fault(Portugal) and Implications for Seismic Hazard Assessment

    NASA Astrophysics Data System (ADS)

    Vilanova, S. P.; Meghraoui, M.; Bosi, V.; Fonseca, J. F.

    2001-12-01

    The Lower Tagus Valley (LTV) has been the locus of M6 to M7 onshore historical earthquakes in the vicinity of Lisbon, the best studied being those of 1531 and 1909 (Moreira, 1984). The distribution of damage in these events shows an elongated shape along the river valley, leading several authors to infer the existence of an active fault following the valley (Choffat and Bensaude, 1912; Fonseca, 1989; Cabral, 1995). However, no direct evidence of such structure - other than the occurrence of large earthquakes - was put forward until now. To address this problem we developed a series of geomorphic, geophysical and paleoseismological investigations along the LTV which indicated displacement of drainage system, uplifted alluvial terrace, and the presence of a scarp for a minimum length of 20 km. Upon trenching, we identified NNE-SSW trending thrust planes affecting Pliocene and Holocene formations, and measured a minimum displacement of 3m over the last 4000 years. The age of thrusting was constrained by radiocarbon dating and corroborated by archaeological findings. The most recent faulting event can likely be correlated with the M7 1531 earthquake. The thrust geometry shows a significant left-lateral component, as it is pointed out by the imbricate pattern of fault planes and kinematic indicators (striations), which suggest a N-S direction of maximum compression. A gravitational origin for the deformation exposed in the trenches is discussed and discarded. On a larger scale, fault segments inland may be a continuation of the offshore source of the 1755 Lisbon Earthquake (Vilanova et al., this conference). We present new calculations of seismic hazard for Western Iberia, and discuss the impact of the new seismotectonic data for the Lower Tagus Valley.

  15. Seismo-turbidite Sedimentology: Implications for Active Tectonic Margin Stratigraphy and Sediment Facies Patterns

    NASA Astrophysics Data System (ADS)

    Nelson, C. H.; Goldfinger, C.; Gutierrez Pastor, J.; Polonia, A.; Van Daele, M. E.

    2014-12-01

    Earthquakes generate mass transport deposits (MTDs); megaturbidites (MTD overlain by coeval turbidite); multi-pulsed, stacked, and mud homogenite seismo-turbidites; tsunamites; and seiche deposits. The strongest (Mw 9) earthquake shaking signatures appear to create multi-pulsed individual turbidites, where the number and character of multiple coarse-grained pulses for correlative turbidites generally remain constant both upstream and downstream in different channel systems. Multiple turbidite pulses, that correlate with multiple ruptures shown in seismograms of historic earthquakes (e.g. Chile 1960, Sumatra 2004 and Japan 2011), support this hypothesis. The weaker (Mw = or < 8) (e.g. northern California San Andreas) earthquakes generate dominantly upstream simple fining-up (uni-pulsed) turbidites in single tributary canyons and channels; however, downstream stacked turbidites result from synchronously triggered multiple turbidity currents that deposit in channels below confluences of the tributaries. Proven tsunamites, which result from tsunami waves sweeping onshore and shallow water debris into deeper water, are a fine-grained turbidite cap over other seismo-turbidites. In contrast, MTDs and seismo-turbidites result from slope failures. Multiple great earthquakes cause seismic strengthening of slope sediment, which results in minor MTDs in basin floor turbidite system deposits (e.g. maximum run-out distances of MTDs across basin floors along active margins are up to an order of magnitude less than on passive margins). In contrast, the MTDs and turbidites are equally intermixed in turbidite systems of passive margins (e.g. Gulf of Mexico). In confined basin settings, earthquake triggering results in a common facies pattern of coeval megaturbidites in proximal settings, thick stacked turbidites downstream, and ponded muddy homogenite turbidites in basin or sub-basin centers, sometimes with a cap of seiche deposits showing bi-directional flow patterns.

  16. 3D gravity inversion and Euler deconvolution to delineate the hydro-tectonic regime in El-Arish area, northern Sinai Peninsula

    NASA Astrophysics Data System (ADS)

    Khalil, Mohamed A.; Santos, Fernando M.; Farzamian, Mohammad

    2014-04-01

    Sinai Peninsula occupies a part of the arid zone belt of northern Africa and southwestern Asia. The largest ephemeral stream in the Sinai Peninsula is called Wadi El-Arish, which winds down northward to the Mediterranean Sea. The delta of Wadi El-Arish has been built by the heavy floods of the Wadi. The Quaternary aquifer is the main water supply of the delta of Wadi El-Arish and its vicinities. The combined action of aridity and extensive pumping from the Quaternary aquifer led to a noticeable increase in groundwater salinity. The hydrochemistry and isotope hydrology confirm that the Quaternary aquifer is recharged by an old saline groundwater from the Pre-Quaternary. A hydrogeological connection between Quaternary and Pre-Quaternary aquifers in the form of fault(s) should exist to explain the hydro-tectonic regime of this area. The Bouguer gravity map shows the high gravity anomaly of the doubly plunging anticline of Risan Aniza Mountain to the south of El-Arish area, which is a part of the Syrian Arc System of northern Sinai Peninsula. A 3D density contrast model, 3D Euler deconvolution, horizontal derivative and least square separation have been performed. The findings showed that (1) two deep regional faults extending NE-SW, surround the Risan Aniza anticline, and (2) two deep local N-S faults are in the area of Delta Wadi El-Arish. These deep faults are proposed to bring the deep Cretaceous aquifer into contact with the shallow Quaternary aquifer and work as a hydrogeological connection between both aquifers. The present hypothesis has some geological evidences from the subsurface lithology of the nearby wells.

  17. Edaphics, active tectonics and animal movements in the Kenyan Rift - implications for early human evolution and dispersal

    NASA Astrophysics Data System (ADS)

    Kübler, Simon; Owenga, Peter; Rucina, Stephen; King, Geoffrey C. P.

    2014-05-01

    The quality of soils (edaphics) and the associated vegetation strongly controls the health of grazing animals. Until now, this has hardly been appreciated by paleo-anthropologists who only take into account the availability of water and vegetation in landscape reconstruction attempts. A lack of understanding the importance of the edaphics of a region greatly limits interpretations of the relation between our ancestors and animals over the last few million years. If a region lacks vital trace elements then wild grazing and browsing animals will avoid it and go to considerable length and take major risks to seek out better pasture. As a consequence animals must move around the landscape at different times of the year. In complex landscapes, such as tectonically active rifts, hominins can use advanced group behaviour to gain strategic advantage for hunting. Our study in the southern Kenya rift in the Lake Magadi region shows that the edaphics and active rift structures play a key role in present day animal movements as well as the for the location of an early hominin site at Mt. Olorgesailie. We carried out field analysis based on studying the relationship between the geology and soil development as well as the tectonic geomorphology to identify 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We further sampled different soils that developed on the volcanic bedrock and sediment sources of the region and interviewed the local Maasai shepherds to learn about present-day good and bad grazing sites. At the Olorgesailie site the rift valley floor is covered with flood trachytes; basalts only occur at Mt. Olorgesailie and farther east up the rift flank. The hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. The lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by basalt flows from Mt. Olorgesailie

  18. Evidence of active tectonics on a Roman aqueduct system (II-III century A.D.) near Rome, Italy

    NASA Astrophysics Data System (ADS)

    Marra, Fabrizio; Montone, Paola; Pirro, Mario; Boschi, Enzo

    2004-04-01

    In this paper we describe evidence of strong tectonic deformation affecting two aqueducts of Roman age (II-III century A.D.). The channels are located approximately 20 km northeast of Rome along the ancient Via Tiburtina. Brittle and ductile deformation affects these two structures, including extensional joint systems, NE-oriented faults, and horizontal distortion. This deformation is consistent with right-lateral movement on major N-striking faults, and represents the first evidence that tectonic deformation took place in historical times in the vicinity of Rome, with local strike-slip movement superimposed on a regional extensional fault system.

  19. Repeated large-magnitude earthquakes in a tectonically active, low-strain continental interior: The northern Tien Shan, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Landgraf, A.; Dzhumabaeva, A.; Abdrakhmatov, K. E.; Strecker, M. R.; Macaulay, E. A.; Arrowsmith, Jr.; Sudhaus, H.; Preusser, F.; Rugel, G.; Merchel, S.

    2016-05-01

    The northern Tien Shan of Kyrgyzstan and Kazakhstan has been affected by a series of major earthquakes in the late 19th and early 20th centuries. To assess the significance of such a pulse of strain release in a continental interior, it is important to analyze and quantify strain release over multiple time scales. We have undertaken paleoseismological investigations at two geomorphically distinct sites (Panfilovkoe and Rot Front) near the Kyrgyz capital Bishkek. Although located near the historic epicenters, both sites were not affected by these earthquakes. Trenching was accompanied by dating stratigraphy and offset surfaces using luminescence, radiocarbon, and 10Be terrestrial cosmogenic nuclide methods. At Rot Front, trenching of a small scarp did not reveal evidence for surface rupture during the last 5000 years. The scarp rather resembles an extensive debris-flow lobe. At Panfilovkoe, we estimate a Late Pleistocene minimum slip rate of 0.2 ± 0.1 mm/a, averaged over at least two, probably three earthquake cycles. Dip-slip reverse motion along segmented, moderately steep faults resulted in hanging wall collapse scarps during different events. The most recent earthquake occurred around 3.6 ± 1.3 kyr ago (1σ), with dip-slip offsets between 1.2 and 1.4 m. We calculate a probabilistic paleomagnitude to be between 6.7 and 7.2, which is in agreement with regional data from the Kyrgyz range. The morphotectonic signals in the northern Tien Shan are a prime example of deformation in a tectonically active intracontinental mountain belt and as such can help understand the longer-term coevolution of topography and seismogenic processes in similar structural settings worldwide.

  20. Complex Tectonism on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Complex tectonism is evident in these images of Ganymede's surface. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. The 80 kilometer (50 mile) wide lens-shaped feature in the center of the image is located at 32 degrees latitude and 188 degrees longitude along the border of a region of ancient dark terrain known as Marius Regio, and is near an area of younger bright terrain named Nippur Sulcus. The tectonism that created the structures in the bright terrain nearby has strongly affected the local dark terrain to form unusual structures such as the one shown here. The lens-like appearance of this feature is probably due to shearing of the surface, where areas have slid past each other and also rotated slightly. Note that in several places in these images, especially around the border of the lens-shaped feature, bright ridges appear to turn into dark grooves. Analysis of the geologic structures in areas like this are helping scientists to understand the complex tectonic history of Ganymede.

    North is to the top-left of the image, and the sun illuminates the surface from the southeast. The image covers an area about 63 kilometers (39 miles) by 120 kilometers (75 miles) across at a resolution of 188 meters (627 feet) per picture element. The images were taken on September 6, 1996 at a range of 18,522 kilometers (11,576 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  1. Extensional tectonics on continents and the transport of heat and matter

    NASA Technical Reports Server (NTRS)

    Neugebauer, H. J.

    1985-01-01

    Intracontinental zones of extensional tectonic style are commonly of finite width and length. Associated sedimentary troughs are fault-controlled. The evolution of those structures is accompanied by volcanic activity of variable intensity. The characteristic surface structures are usually underlaid by a lower crust of the transitional type while deeper subcustal areas show delayed travel times of seismic waves especially at young tectonic provinces. A correspondence between deep-seated processes and zones of continental extension appears obvious. A sequential order of mechanisms and their importance are discussed in the light of modern data compilations and quantitative kinematic and dynamic approaches. The Cenozoic exensional tectonics related with the Rhine River are discussed.

  2. Control of salt tectonics by young basement tectonics in Brazil`s offshore basins

    SciTech Connect

    Szatmari, P.; Mohriak, W.

    1995-08-01

    The Campos basin (offshore SE Brazil) is one of the most successful areas of oil exploration in South America. Discovered 20 years ago, its production (500,000 b/d) and reserves (2.9 billion barrels) are second only to Venezuela`s. This richness is due, to a large extent, to intense salt tectonics and the abundance of turbidites. Reactivated basement structures onshore provide a unique opportunity to understand the role of young basement tectonics in controlling salt tectonics and petroleum occurrence. The mountains of SE Brazil, over 1500 m high, formed by the reactivation of late Precambrian thrust and wrench zones under E-W compression, presumably caused by Mid-Atlantic ridge push. Coastal mountain ranges, up to 3000 m high, are limited to the segment of the Atlantic between the Vitoria-Trindade hotspot chain and the Rio Grande Rise. The coastal ranges formed as this segment of oceanic crust and adjacent continental margin were pushed WSW along a reactivated Precambrian wrench zone. To the north of this segment, salt tectonics is mostly due to basinward sliding on a tilted salt layer. Along the coastal ranges, to this is added basinward escape of the salt from beneath prograding sediments derived from the rising mountains. Extension above the salt tends to be compensated by compression farther basinward. Salt canopies, frequent in the Gulf of Mexico, occur only near the Abrolhos hotspot, where high temperatures during volcanic activity sharply reduced the viscosity of the salt.

  3. Stratigraphic contrasts and tectonic relationships between Carboniferous successions in the Trans-Alaska Crustal Transect corridor and adjacent areas, northern Alaska

    USGS Publications Warehouse

    Dumoulin, J.A.; Watts, K.F.; Harris, A.G.

    1997-01-01

    The Carboniferous succession along the Trans-Alaska Crustal Transect (TACT) corridor in the Atigun Gorge area of the central Brooks Range consists of the Kayak Shale (Kinderhookian) and the Lisburne Group (Kinderhookian through Chesterian). The Kayak Shale is at least 210 m thick; it is chiefly black, noncalcareous shale with several limestone beds of pelmatozoan-bryozoan packstone and formed in an open-marine setting. The Lisburne Group is a carbonate rock succession about 650 m thick and consists mainly of skeletal packstone, wackestone, and mudstone which contain locally abundant calcispheres, ostracodes, algae, and sponge spicules; it accumulated largely in a shallow water platform environment with restricted circulation. This restriction was probably produced by a coeval belt of skeletal sand shoals recognized 70 km to the west in the Shainin Lake area. Significant and apparently abrupt shifts in the age and lithofacies of Carboniferous strata occur across the central and eastern Brooks Range. These shifts are most marked in a zone roughly coincident with what is interpreted by many workers to be the leading edge of the Endicott Mountains allochthon. Notable lithologic contrasts are also observed, however, between sections in the northern and southern parts of the Endicott Mountains allochthon. This suggests that considerable tectonic shortening has taken place within the allochthon, as well as between it and parautochthonous rocks to the northeast. The Carboniferous section near Mount Doonerak is more similar in age and lithofacies to coeval sections in the central Brooks Range that are considered allochthonous than to parautochthonous sections to the northeast. Copyright 1997 by the American Geophysical Union.

  4. Temporal and spatial complexity in post-glacial sedimentation on the tectonically active, Poverty Bay continental margin of New Zealand

    NASA Astrophysics Data System (ADS)

    Orpin, Alan R.; Alexander, Clark; Carter, Lionel; Kuehl, Steve; Walsh, J. P.

    2006-11-01

    On the eastern Raukumara Ranges of the New Zealand East Coast, active tectonics, vigorous weather systems, and human colonisation have combined to cause widespread erosion of the mudstone- and sandstone-dominated hinterland. The Waipaoa River sedimentary dispersal system is an example that has responded to environmental change, and is now New Zealand's second largest river in terms of suspended sediment discharge. This paper presents new sediment accumulation rates for the continental shelf and slope that span century to post-glacial time scales. These data are derived from radiochemical tracer, palynological, tephrostratigraphic, and seismic methods. We hypothesise on the temporal and spatial complexity of post-glacial sedimentation across the margin and identify the broad extent of sediment dispersal from the Waipaoa system. The ˜15 km 3 Poverty Bay mid-shelf basin lies adjacent to the mouth of the Waipaoa River, reaching a maximum thickness of ˜45 m. A post-glacial mud lobe of an additional ˜3 km 3 extends through the Poverty Gap and out onto the uppermost slope, attaining 40 m thickness in a structurally controlled sub-basin. Here, an offset in the last-glacial erosion surface indicates that deposition was sympathetic with fault activity and the creation of accommodation space, implying that sedimentation was not supply limited. Contrary to classical shelf sedimentation models, the highest modern accumulation rate of 1 cm y -1 occurs on the outer-shelf sediment lobe, approximately ˜2 times the rate recorded at the mid-shelf basin depocentre, and ˜10 times faster than the excess 210Pb rates estimated from the slope. Pollen records from slope cores fingerprint Polynesian then European settlement, and broaden the spatial extent of post-settlement sedimentation initially documented from the Poverty Bay mid-shelf. Changes in sub-millennial sedimentation infer a 2-3-times increase in post-settlement accumulation on the shelf but a smaller 1-2 times increase on

  5. Global Tectonics on Ganymede

    NASA Technical Reports Server (NTRS)

    Thomas, P. G.; Forni, O. P.; Masson, P. L.

    1985-01-01

    Three large basin surroundings on Ganymede located on grooved terrains, which are supposed to be intensely tectonized areas were studied. All rectilinear morphological elements such as ridges, block edges; and parts of scarps were mapped. The geometric properties (grid pattern) characteristics were determined and a history for the formation of the Ganymede basins studied is proposed. Results indicate that the grooved terrains are very surficial layers, and that their formation does not significantly affect, disturb or rotate the basement. This is in agreement with the conclusion obtained from completely different data (crosscutting relationships between groove sets and their basements).

  6. Mars tectonics and volcanism

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.

    1990-01-01

    The focus of this research was on three broad areas: (1) the relation between lithospheric stress in the vicinity of a growing volcano and the evolution of eruption characteristics and tectonic faulting; (2) the relation between elastic lithosphere thickness and thermal structure; and (3) a synthesis of constraints on heat flow and internal dynamics on Mars. The two reports presented are: (1) Heterogeneities in the Thickness of the Elastic Lithosphere of Mars--Constraints on Heat Flow and Internal Dynamics; and (2) State of Stress, Faulting, and Eruption Characteristics of Large Volcanoes on Mars.

  7. Hydrothermal activity on the southern Mid-Atlantic Ridge: Tectonically- and volcanically-controlled venting at 4 5°S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Murton, B. J.; Parson, L. M.; Prien, R. D.; Ramirez-Llodra, E.; Jakuba, M.; Shank, T. M.; Yoerger, D. R.; Baker, E. T.; Walker, S. L.; Nakamura, K.

    2008-09-01

    We report results from an investigation of the geologic processes controlling hydrothermal activity along the previously-unstudied southern Mid-Atlantic Ridge (3-7°S). Our study employed the NOC (UK) deep-tow sidescan sonar instrument, TOBI, in concert with the WHOI (USA) autonomous underwater vehicle, ABE, to collect information concerning hydrothermal plume distributions in the water column co-registered with geologic investigations of the underlying seafloor. Two areas of high-temperature hydrothermal venting were identified. The first was situated in a non-transform discontinuity (NTD) between two adjacent second-order ridge-segments near 4°02'S, distant from any neovolcanic activity. This geologic setting is very similar to that of the ultramafic-hosted and tectonically-controlled Rainbow vent-site on the northern Mid-Atlantic Ridge. The second site was located at 4°48'S at the axial-summit centre of a second-order ridge-segment. There, high-temperature venting is hosted in an ˜ 18 km 2 area of young lava flows which in some cases are observed to have flowed over and engulfed pre-existing chemosynthetic vent-fauna. In both appearance and extent, these lava flows are directly reminiscent of those emplaced in Winter 2005-06 at the East Pacific Rise, 9°50'N and reference to global seismic catalogues reveals that a swarm of large (M 4.6-5.6) seismic events was centred on the 5°S segment over a ˜ 24 h period in late June 2002, perhaps indicating the precise timing of this volcanic eruptive episode. Temperature measurements at one of the vents found directly adjacent to the fresh lava flows at 5°S MAR (Turtle Pits) have subsequently revealed vent-fluids that are actively phase separating under conditions very close to the Critical Point for seawater, at ˜ 3000 m depth and 407 °C: the hottest vent-fluids yet reported from anywhere along the global ridge crest.

  8. Active tectonic extension across the Alto Tiberina normal fault system from GPS data modeling and InSAR velocity maps: new perspectives within TABOO Near Fault Observatory

    NASA Astrophysics Data System (ADS)

    Vadacca, Luigi; Anderlini, Letizia; Casarotti, Emanuele; Serpelloni, Enrico; Chiaraluce, Lauro; Polcari, Marco; Albano, Matteo; Stramondo, Salvatore

    2014-05-01

    The Alto Tiberina fault (ATF) is a low-angle (east-dipping at 15°) normal fault (LANF) 70 km long placed in the Umbria-Marche Apennines (central Italy), characterized by SW-NE oriented extension occurring at rates of 2-3 mm/yr. These rates were measured by continuous GPS stations belonging to several networks, which are denser in the study area thanks to additional sites recently installed in the framework of the INGV national RING network and of the ATF observatory. In this area historical and instrumental earthquakes mainly occur on west-dipping high-angle normal faults. Within this context the ATF has accumulated 2 km of displacement over the past 2 Ma, but at the same time the deformation processes active along this misoriented fault, as well as its mechanical behavior, are still unknown. We tackle this issue by solving for interseismic deformation models obtained by two different methods. At first, through the 2D and 3D finite element modeling, we define the effects of locking depth, synthetic and antithetic fault activity and lithology on the velocity gradient measured along the ATF system. Subsequently through a block modeling approach, we model the GPS velocities by considering the major fault systems as bounds of rotating blocks, while estimating the corresponding geodetic fault slip-rates and maps of heterogeneous fault coupling. Thanks to the latest imaging of the ATF deep structure obtained from seismic profiles, we improve the proposed models by modeling the fault as a complex rough surface to understand where the stress accumulations are located and the interseismic coupling changes. The preliminary results obtained show firstly that the observed extension is mainly accommodated by interseismic deformation on both the ATF and antithetic faults, highlighting the important role of this LANF inside an active tectonic contest. Secondarily, using the ATF surface "topography", we find an interesting correlation between microseismicty and creeping portions

  9. Middle-Late Mesozoic sedimentary provenances of the Luxi and Jiaolai areas: Implications for tectonic evolution of the North China Block

    NASA Astrophysics Data System (ADS)

    Xu, Jianqiang; Li, Zhong

    2015-11-01

    Provenances of sedimentary rocks may provide important constraints on the tectonic evolution of the North China Block (NCB). Previous studies have demonstrated that the northern NCB (NNCB) and the Xing-Meng orogenic belt (XMOB) supplied massive detritus southward into the hinterland of the NCB during the Jurassic. In order to study the evolution of sedimentary provenance during the Middle-Late Mesozoic, U-Pb geochronology and Hf isotopic geochemistry of detrital zircon grains and chemical compositions of detrital garnets from sandstones in the Luxi and Jiaolai areas, eastern NCB, were analyzed in combination with published data on the Jurassic sandstones. The Late Paleozoic-Mesozoic (367-139 Ma) zircons in the lowermost Cretaceous Mengyin Formation samples from the Luxi area show εHf(t) values of -15.3 to -3.2 and +1.3 to +10.0, which are very similar to the results of analyses of the Jurassic formations. Further, the increased amount of Mesozoic zircons and granulite-derived garnets in the Mengyin Formation samples, compared to those in the Jurassic samples, indicates there was more detritus supply from the NNCB than from the XMOB. In the overlying Qingshan Formation samples, zircon grains do not exhibit Paleozoic ages, but most of them have Early Cretaceous ages and negative εHf(t) values, which are similar to the zircon grains extracted from the widespread Early Cretaceous igneous rocks in the NCB. This suggests that the provenance might have changed to a locally derived source. In contrast, the zircon population of the Early Cretaceous sandstones from the Jiaolai basin is dominated by grains of mid-Neoproterozoic age (700-900 Ma) which signifies contribution from the Sulu orogen. Moreover, the detrital garnet assemblages of sandstones in the Luxi area are not consistent with those from representative metamorphic rocks in the Sulu orogen. The above results seem to confirm that the Mesozoic sedimentary provenance of the Luxi area had no evident connection with

  10. Active strike-slip faulting history inferred from offsets of topographic features and basement rocks: a case study of the Arima Takatsuki Tectonic Line, southwest Japan

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2002-01-01

    Geological, geomorphological and geophysical data have been used to determine the total displacement, slip rates and age of formation of the Arima-Takatsuki Tectonic Line (ATTL) in southwest Japan. The ATTL is an ENE-WSW-trending dextral strike-slip fault zone that extends for about 60 km from northwest of the Rokko Mountains to southwest of the Kyoto Basin. The ATTL marks a distinct topographic boundary between mountainous regions and basin regions. Tectonic landforms typically associated with active strike-slip faults, such as systematically-deflected stream channels, offset ridges and fault scarps, are recognized along the ATTL. The Quaternary drainage system shows progressive displacement along the fault traces: the greater the magnitude of stream channel, the larger the amount of offset. The maximum dextral deflection of stream channels is 600-700 m. The field data and detailed topographic analyses, however, show that pre-Neogene basement rocks on both sides of the ATTL are displaced by about 16-18 km dextrally and pre-Mio-Pliocene elevated peneplains are also offset 16-17 km in dextral along the ATTL. This suggests that the ATTL formed in the period between the development of the pre-Mio-Pliocene peneplains and deflection of the Quaternary stream channels. The geological, geomorphological and geophysical evidence presented in this study indicates that (1) the ATTL formed after the mid-Miocene, (2) the ATTL has moved as a dextral strike-slip fault with minor vertical component since its formation to late Holocene and (3) the ATTL is presently active with dextral slip rates of 1-3 mm/year and a vertical component of >0.3 mm/year. The formation of the ATTL was probably related to the opening of the Japan Sea, which is the dominant tectonic event around Japan since mid-Miocene. The case study of the ATTL provides insight into understanding the tectonic history and relationship between tectonic landforms and structures in active strike-slip faults.

  11. Climatically controlled formation of river terraces in a tectonically active region along the southern piedmont of the Tian Shan, NW China

    NASA Astrophysics Data System (ADS)

    Huang, Wei-liang; Yang, Xiao-ping; Li, An; Thompson, Jessica A.; Zhang, Ling

    2014-09-01

    Combined tectonic uplift and Quaternary climate variability control the deposition and abandonment of terraces along the southern Tian Shan in northwest China. Several preserved terraces have been deformed by an actively growing anticline within the uplifted frontal thrust system of the southern Tian Shan. We combine geomorphic mapping, topographic surveys of the deformed terrace surfaces, 10Be terrestrial cosmogenic nuclide (TCN) depth profile dating, and optically stimulated luminescence (OSL) dating to develop a new chronology for the terraces along the Huangshui He since 550 ka. Our in situ 10Be dating of fluvial gravels capping strath terraces suggests a relationship between the formation and abandonment of the terraces and glacial climate cycles since the middle-late Pleistocene. These data indicate that the formation of the four terraces occurred at ~ 550, ~ 430, ~ 350, and ~ 60 ka. We suggest that episodes of aggradation were facilitated by high sediment supply during glacial periods, followed by subsequent incision that led to abandonment of these terraces during deglaciation. We also estimate that tectonically induced river incision may account for about 60-70% of the total incision. However, during the intervening time between 350 ka and present, only one terrace was formed and preserved. We suggest that this record might be caused by a gradually decreasing uplift rate of the anticline through time and thus has influenced the preservation of terraces. Therefore, our results demonstrate the utility of chronologic records from southern Tian Shan for deconvolving the effects of tectonics and climate on fluvial incision.

  12. Seismic source study of the Racha-Dzhava (Georgia) earthquake from aftershocks and broad-band teleseismic body-wave records: An example of active nappe tectonics

    USGS Publications Warehouse

    Fuenzalida, H.; Rivera, L.; Haessler, H.; Legrand, D.; Philip, H.; Dorbath, L.; McCormack, D.; Arefiev, S.; Langer, C.; Cisternas, A.

    1997-01-01

    The Racha-Dzhava earthquake (Ms = 7.0) that occurred on 1991 April 29 at 09:12:48.1 GMT in the southern border of the Great Caucasus is the biggest event ever recorded in the region, stronger than the Spitak earthquake (Ms = 6.9) of 1988. A field expedition to the epicentral area was organised and a temporary seismic network of 37 stations was deployed to record the aftershock activity. A very precise image of the aftershock distribution is obtained, showing an elongated cloud oriented N105??, with one branch trending N310?? in the western part. The southernmost part extends over 80 km, with the depth ranging from 0 to 15 km, and dips north. The northern branch, which is about 30 km long, shows activity that ranges in depth from 5 to 15 km. The complex thrust dips northwards. A stress-tensor inversion from P-wave first-motion polarities shows a state of triaxial compression, with the major principal axis oriented roughly N-S, the minor principal axis being vertical. Body-waveform inversion of teleseismic seismograms was performed for the main shock, which can be divided into four subevents with a total rupture-time duration of 22 s. The most important part of the seismic moment was released by a gentle northerly dipping thrust. The model is consistent with the compressive tectonics of the region and is in agreement with the aftershock distribution and the stress tensor deduced from the aftershocks. The focal mechanisms of the three largest aftershocks were also inverted from body-wave records. The April 29th (Ms = 6.1) and May 5th (Ms = 5.4) aftershocks have thrust mechanisms on roughly E-W-oriented planes, similar to the main shock. Surprisingly, the June 15th (Ms = 6.2) aftershock shows a thrust fault striking N-S. This mechanism is explained by the structural control of the rupture along the east-dipping geometry of the Dzirula Massif close to the Borzhomi-Kazbeg strike-slip fault. In fact, the orientation and shape of the stress tensor produce a thrust on a N

  13. The Deccan tholeiite lavas and dykes of Ghatkopar-Powai area, Mumbai, Panvel flexure zone: Geochemistry, stratigraphic status, and tectonic significance

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Zellmer, Georg F.; Demonterova, Elena I.; Ivanov, Alexei V.; Kumar, Rohit; Patel, Rakesh Kumar

    2014-04-01

    Mumbai City, situated on the western Indian coast, is well known for exposures of late-stage Deccan pillow basalts and spilites, pyroclastic rocks, rhyolite lavas, and trachyte intrusions. These rock units, and a little-studied sequence of tholeiitic flows and dykes in the eastern part of Mumbai City, constitute the west-dipping limb of a regional tectonic structure called the Panvel flexure. Here we present field, petrographic, major and trace element and Sr-Nd isotopic data on these tholeiitic flows and dykes, best exposed in the Ghatkopar-Powai area. The flows closely resemble the Mahabaleshwar Formation of the thick Western Ghats sequence to the east, in Sr-Nd isotopic ratios and multielement patterns, but have other geochemical characteristics (e.g., incompatible trace element ratios) unlike the Mahabaleshwar or any other Formation. The flows may have originated from a nearby eruptive center, possibly offshore of Mumbai. Two dykes resemble the Ambenali Formation of the Western Ghats in all geochemical characteristics, though they may not represent feeders of the Ambenali Formation lavas. Most dykes are distinct from any of the Western Ghats stratigraphic units. Some show partial (e.g., Sr-Nd isotopic) similarities to the Mahabaleshwar Formation, and these include several dykes with unusual, concave-downward REE patterns suggesting residual amphibole and thus a lithospheric source. The flows and dykes are inferred to have undergone little or no contamination, by lower continental crust. Most dykes are almost vertical, suggesting emplacement after the formation of the Panvel flexure, and indicate considerable east-west lithospheric extension during this late but magmatically vigorous stage of Deccan volcanism.

  14. Using earthquake-triggered landslides as a hillslope-scale shear strength test: Insights into rock strength properties at geomorphically relevant spatial scales in high-relief, tectonically active settings

    NASA Astrophysics Data System (ADS)

    Gallen, Sean; Clark, Marin; Godt, Jonathan; Lowe, Katherine

    2016-04-01

    obtained using typical laboratory shear strength measurements on intact rock samples. Furthermore, the near-surface material strength is similar between the study areas despite differences in tectonic, climatic, and lithologic conditions. Variations in near-surface strength within each setting appear to be more strongly associated with factors contributing to the weakening rock through chemical or physical weathering, such as mean annual precipitation and distance to active faults (a proxy for rock shattering intensity), rather than intrinsic lithologic properties. We hypothesize that the shattering of rock through long-term permanent strain accumulation and by repeated earthquakes is an important mechanism that can explain low rock strength values among the different study sites and the spatial pattern of rock strength within each location. These findings emphasize the potential role of factors other than lithology in controlling the spatial distribution of near-surface rock strength in high-relief, tectonically active settings, which has important implications for understanding the evolution of landscapes, interpreting tectonic and climatic signals from topography, critical zone processes, and natural hazard assessment.

  15. Linking mantle dynamics, plate tectonics and surface processes in the active plate boundary zones of eastern New Guinea (Invited)

    NASA Astrophysics Data System (ADS)

    Baldwin, S.; Moucha, R.; Fitzgerald, P. G.; Hoke, G. D.; Bermudez, M. A.; Webb, L. E.; Braun, J.; Rowley, D. B.; Insel, N.; Abers, G. A.; Wallace, L. M.; Vervoort, J. D.

    2013-12-01

    Eastern New Guinea lies within the rapidly obliquely converging Australian (AUS)- Pacific (PAC) plate boundary zone and is characterized by transient plate boundaries, rapidly rotating microplates and a globally significant geoid high. As the AUS plate moved northward in the Cenozoic, its leading edge has been a zone of subduction and arc accretion. The variety of tectonic settings in this region permits assessment of the complex interplay among mantle dynamics, plate tectonics, and surface processes. Importantly, the timescale of tectonic events (e.g., subduction, (U)HP exhumation, seafloor spreading) are within the valid bounds of mantle convection models. A record of changes in bathymetry and topography are preserved in high standing mountain belts, exhumed extensional gneiss domes and core complexes, uplifted coral terraces, and marine sedimentary basins. Global seismic tomography models indicate accumulation of subducted slabs beneath eastern New Guinea at the bottom of the upper mantle (i.e., <660km depth). Some of the deeply subducted material may indeed be buoyant subducted AUS continental margin (to depths of ~250-300 km), as well as subducted continental material that has reached the point of no return (i.e., > 250-300 km). Preliminary global-scale backward advected mantle convection models, driven by density inferred from joint seismic-geodynamic tomography models, exhibit large-scale flow associated with these subducted slab remnants and predict the timing and magnitude (up to 1500 m) of dynamic topography change (both subsidence and uplift) since the Oligocene. In this talk we will explore the effects of large-scale background mantle flow and plate tectonics on the evolution of topography and bathymetry in eastern New Guinea, and discuss possible mechanisms to explain basin subsidence and surface uplift in the region.

  16. Carboniferous sedimentation and tectonics in southern Morocco

    SciTech Connect

    Harris, J.P.; Crossley, R.; Aktas, G.; Matthews, S.J.; Boudda, A.

    1988-08-01

    The Carboniferous rocks of southern Morocco record the gradual change from the extensional tectonic style of the early Paleozoic to a compressional regime. During the Tournaisian and early Visean, northwest compression formed a rising anticline in the Anti-Atlas, which provided sediments to shallow marine basins formed in the flanking synclines. During the late Visean, tectonic activity increased markedly, and northward-downthrowing normal/oblique slip faulting formed submarine fault scarps. Turbidity currents and debris flows together with giant exotic blocks were shed northward from these scarps. The turbidity currents were deflected eastward to flow down the axes of these small easterly plunging marine basins. A late Visean phase of minor folding with locally developed cleavage and quartz veining closed these basins. The folded sequences are unconformably overlain by uppermost Visean fluvial sediments deposited from northward and eastward-flowing rivers. During the Pennsylvanian, collisional tectonics recorded in the Moroccan Meseta to the north were probably responsible for thrust faulting and the formation of a high-angle cleavage. Thick (up to 4.5 km) sandstones and conglomerates with red mudstones, paleosols, and coals are preserved on the fringes of the area. These were deposited by southeast-flowing rivers and are interpreted as the eroded remnants of a syn-postorogenic molasse deposited in a major foredeep south of the main orogen.

  17. Active tectonics west of New Zealand's Alpine Fault: South Westland Fault Zone activity shows Australian Plate instability

    NASA Astrophysics Data System (ADS)

    De Pascale, Gregory P.; Chandler-Yates, Nicholas; Dela Pena, Federico; Wilson, Pam; May, Elijah; Twiss, Amber; Cheng, Che

    2016-04-01

    The 300 km long South Westland Fault Zone (SWFZ) is within the footwall of the Central Alpine Fault (<20 km away) and has 3500 m of dip-slip displacement, but it has been unknown if the fault is active. Here the first evidence for SWFZ thrust faulting in the "stable" Australian Plate is shown with cumulative dip-slip displacements up to 5.9 m (with 3 m throw) on Pleistocene and Holocene sediments and gentle hanging wall anticlinal folding. Cone penetration test (CPT) stratigraphy shows repeated sequences within the fault scarp (consistent with thrusting). Optically stimulated luminescence (OSL) dating constrains the most recent rupture post-12.1 ± 1.7 ka with evidence for three to four events during earthquakes of at least Mw 6.8. This study shows significant deformation is accommodated on poorly characterized Australian Plate structures northwest of the Alpine Fault and demonstrates that major active and seismogenic structures remain uncharacterized in densely forested regions on Earth.

  18. Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: Observations in groundwaters along the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Deeds, Daniel A.; Kulongoski, Justin T.; Mühle, Jens; Weiss, Ray F.

    2015-02-01

    Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge (Cre; ∼30 fmol kg-1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1-9 times Cre), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10-980 times Cre) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20-100 km) suggests that the SAFS potentially emits (0.3- 1) ×10-1 kg CF4 yr-1 to the Earth's surface. For comparison, the chemical weathering of ∼ 7.5 ×104km2 of granitic rock in California is estimated to release (0.019- 3.2) ×10-1 kg CF4 yr-1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial-interglacial transitions.

  19. The analysis of interseismic GPS observation and its implication to seismic activity in Taiwan area

    NASA Astrophysics Data System (ADS)

    Tsai, M. C.; Yu, S. B.; Shin, T. C.

    2015-12-01

    Taiwan is an active tectonic area with about 80 mm/yr plate convergence rate. To understand the crustal deformation and seismic potential in Taiwan area. We derived 2009-2014 interseismic GPS velocity field and strain rate, implicate to seismic activity of 2005-2014. Data collected by 281 sites of Taiwan Continuous GPS (cGPS) Array and processed with GAMIT/GLOBK software. Stacking of power spectral densities from cGPS data in Taiwan, we found the errors type can be described as a combination of white noise and flicker noise. The common errors are removed by stacking 50 cGPS sites with data period larger than 5 years. By removing the common errors, the precision of GPS data has been further improved to 2.3 mm, 1.9 mm, and 6.9 mm in the E, N, U components, respectively. After strictly data quality control, time series analysis and noise analysis, we derive an interseismic ITRF2008 velocity field from 2009 to 2014 in the Taiwan area. The general pattern is quite similar with previous studies, but the station density is much larger and spatial coverage better. Based on this interseismic velocity field, we estimate the crustal strain rate in Taiwan area. Approximately half of plate convergence strain rate is accommodated on the fold and thrust belt of western Taiwan and another half is taken up in the Longitudinal Valley and the Coastal Range in eastern Taiwan. The maximum dilatation rates is about -0.75~-0.9 μstrain/yr in WNW-ESE direction. The velocities in western Taiwan generally show a fan-shaped pattern, consistent with the direction of maximum compression tectonic stress. Extension in the E-W direction is observed at the Central Range area, the focal mechanism results also indicate the earthquake type here most are normal faults. In northern Taiwan, the velocity vectors reveal clockwise rotation, indicating the on-going extensional deformation related to the back-arc extension of the Okinawa Trough. In southern Taiwan, the horizontal velocity increases from

  20. Active Uplift At The Taiwan Belt Front Revealed By River Profiles:the Hsiaomei Anticline Area

    NASA Astrophysics Data System (ADS)

    Chen, R.-F.; Angelier, J.; Hu, J.-C.; Deffontaines, B.; Tsai, H.

    A river profile may reveal tectonic deformation through comparison with a smoothed theoretical function based on simple assumptions, provided that its relationships with the erosion-accumulation phenomena have been deciphered. The Taiwan orogeny re- sults from the collision between the Luzon volcanic arc of the Philippine Sea plate and the Chinese continental margin of the Eurasian plate. As an active collision zone between the Luzon arc and the China continental margin, the Taiwan mountain belt, particularly its south-central part, is undergoing strong crustal shortening and rapid uplift. In the central part of the island, rock uplift rates are matched by erosion rates calculated from sediment yields and exhumation rates. In the foothills of southwestern Taiwan we focus on the longitudinal profiles of twelve rivers near Chiayi area. Based on the fit with mathematical functions, we characterize a significant positive anomaly in terms of shape, amplitude and location. River data from 1/5,000 topographic maps were used to define a set of parameters related to the classical exponential equation of the longitudinal profiles. We obtained an accepted fit for a set of 5-7 parameters of the polynomial exponent, that is, a degree 4-6. The anomaly is spatially consistent and does not show correlation with variations in erosional-depositional phenomena, including variations in lithology of the rock formations. The anomaly thus reflects tectonic uplift, in good agreement with other sources of information, including the GPS data that indicate active E-W shortening of about 1 cm/yr in this area. The posi- tive anomaly detected in ten river profiles diminishes and vanishes in the northernmost and southernmost river profiles. It reflects continuing folding and uplift within an ellip- tic area elongated N-S, which corresponds to the present-day growth of the Hsiaomei anticline at the front of Taiwan belt.

  1. Tectonics of the Easter plate

    NASA Technical Reports Server (NTRS)

    Engeln, J. F.; Stein, S.

    1984-01-01

    A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

  2. Caribbean paleomagnetism and tectonic evolution

    SciTech Connect

    MacDonald, W.D.

    1985-01-01

    Approximately fifty papers treating diverse aspects of Caribbean paleomagnetism have appeared since Creer's pioneering work in the early 1960s. Apparently anomalous early results were initially attributed to anomalous geomagnetic field behavior, to unusual mineralogic effects in rock magnetism and to complex remagnetizations. Eventually the importance of structural and tectonic influences were recognized in paleomagnetic data of the Caribbean area, as elsewhere. Large tectonic rotation is evident from the unusual paleomagnetic declination found at many Caribbean localities. Latitudinal transport, with its plate motion implications, is more subtly expressed in the paleomagnetic inclination parameter, with its typically large relative variance. A review of Caribbean paleomagnetic data is given to form a basis for composing realistic tectonic models.

  3. Analysis of tectonic features in US southwest from Skylab photographs

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator); Tubbesing, L.

    1975-01-01

    The author has identified the following significant results. Skylab photographs were utilized to study faults and tectonic lines in selected areas of the U.S. Southwest. Emphasis was on elements of the Texas Zone in the Mojave Desert and the tectonic intersection in southern Nevada. Transverse faults believed to represent the continuation of the Texas Zone were found to be anomalous in strike. This suggests that the Mojave Desert block was rotated counterclockwise as a unit with the Sierra Nevada. Left-lateral strike-slip faults in Lake Mead area are interpreted as elements of the Wasatch tectonic zone; their anomalous trend indicates that the Lake Mead area has rotated clockwise with the Colorado Plateau. A tectonic model relating major fault zones to fragmentation and rotation of crustal blocks was developed. Detailed correlation of the high resolution S190B metric camera photographs with U-2 photographs and geologic maps demonstrates the feasibility of utilizing S190B photographs for the identification of geomorphic features associated with recent and active faults and for the assessment of seismic hazards.

  4. Tectonic evolution of northern Wadi Araba, Jordan

    NASA Astrophysics Data System (ADS)

    Atallah, Mohammad

    1992-03-01

    In the area east of northern Wadi Araba several phases of tectonic fracturing can be distinguished. The oldest is of Precambrian age and is represented by a system of dikes. A second, pre-Cretaceous, tectonic phase is represented by a distinct joint system, which is restricted to the Cambrian sediments and has not cut the Cretaceous sediments. The major tectonic movements which lead to the formation of the Dead Sea rift produced faults and joint systems which cut all rock sequences. The major deformation of the area started in the early Tertiary, when the accumulation of the SE-NW directed compressive stresses produced fold structures which are older than the rift movements. As a result of this stress a conjugate system of fractures was produced; ESE-trending right-lateral (antithetic) faults and SSE-trending left-lateral (synthetic) faults. A major group of tensional faults and fractures, trending 130°, was produced due to this compression. The major displacement along the rift followed the formation of the above mentioned faults. These fault systems dissected the area into different blocks. As the compression continued, the faults and the blocks between them were rotated relative to each other. Two phases of rotational movements were recorded, contemporaneous with the two phases of the rift formation. During its northward movement, the Arabian plate came into collision with the Sinai-Palestine plate in the Dahal area in northern Wadi Araba. Various indications prove that the Wadi Araba fault is still active and the northward displacement of the Arabian plate along this fault continues in recent time.

  5. Quantitative morphometric analysis for the tectonic characterisation of northern Tunisia.

    NASA Astrophysics Data System (ADS)

    Camafort, Miquel; Pérez-Peña, José Vicente; Booth-Rea, Guillermo; Ranero, César R.; Gràcia, Eulàlia; Azañón, José Miguel; Melki, Fetheddine; Ouadday, Mohamed

    2016-04-01

    Northern Tunisia is characterized by low deformation rates and low to moderate seismicity. Although instrumental seismicity reaches maximum magnitudes of Mw 5.5, some historical earthquakes have occurred with catastrophic consequences in this region. Aiming to improve our knowledge of active tectonics in Tunisia, we carried out both a quantitative morphometric analysis and field study in the north-western region. We applied different morphometric tools, like river profiles, knickpoint analysis, hypsometric curves and integrals and drainage pattern anomalies in order to differentiate between zones with high or low recent tectonic activity. This analysis helps identifying uplift and subsidence zones, which we relate to fault activity. Several active faults in a sparse distribution were identified. A selected sector was studied with a field campaign to test the results obtained with the quantitative analysis. During the fieldwork we identified geological evidence of recent activity and a considerable seismogenic potential along El Alia-Teboursouk (ETF) and Dkhila (DF) faults. The ETF fault could be responsible of one of the most devastating historical earthquakes in northern Tunisia that destroyed Utique in 412 A.D. Geological evidence include fluvial terraces folded by faults, striated and cracked pebbles, clastic dikes, sand volcanoes, coseismic cracks, etc. Although not reflected in the instrumental seismicity, our results support an important seismic hazard, evidenced by the several active tectonic structures identified and the two seismogenic faults described. After obtaining the current active tectonic framework of Tunisia we discuss our results within the western Mediterranean trying to contribute to the understanding of the western Mediterranean tectonic context. With our results, we suggest that the main reason explaining the sparse and scarce seismicity of the area in contrast with the adjacent parts of the Nubia-Eurasia boundary is due to its extended

  6. Tectonic inheritance and crustal thickening of the Tibetan crust in the Longmen Shan area : Highlights for the origin and the evolution of the eastern part of the Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Pubellier, M.; Robert, A.; de Sigoyer, J.; Lahfid, A.; Billerot, A.; Vergne, J.

    2011-12-01

    The present-day crustal structure of the Longmen Shan highlights an abrupt 18km-high Moho step between the 63km-thick Tibetan crust and the 45km-thick Yangtze craton (figure 1). This crustal contrast is associated with a topographic gradient of about 10% whereas there is almost no present-day horizontal convergence across the range. We perform a pluridisciplinary approach combining seismological imagery, structural geology and metamorphic petrology to study the geodynamic evolution of this mountain range. Our results highlights the importance of the tectonic inheritance in the Longmen Shan area. In fact, several phases of tectonic reactivation in the Longmen Shan since the middle Triassic have been characterized : (1) The indosinian orogeny occured as a consequence of the closure of the Paleotethys and the overflow of the sedimentary pile of the Songpan Garze upon the western part of the Yangtze craton margin. (2) A Cretaceous reactivation (~70-90Ma) which was characterized by a sinistral reactivation of the Wenchuan shear zone located on the western part of the Longmen Shan range. (3) The current tectonic phase as a result of the collision between India and Eurasia and of the eastward motion of the northeastern part of the Tibetan plateau. These results indicate that the crustal growth in the eastern part of the Songpan Garze area is a result of several episodes of thickening of the crust which should be considerated in the geodynamical evolution of the Tibetan plateau.

  7. Numerical modelling of Non Transform Discontinuity geometries: Implications for ridge structure, volcano-tectonic fabric development and hydrothermal activity at segment ends

    NASA Astrophysics Data System (ADS)

    Tyler, S.; Bull, J.; Parson, L.; Tuckwell, G.

    2005-12-01

    Non Transform Discontinuities (NTDs) are a fundamental component of ocean ridge structure and geometry partitioning spreading centres into spatially and temporally independent segments. We use finite difference numerical models to understand the stress distributions associated with a range of NTD geometries. We also apply the models to rotations of volcano-tectonic fabrics observed within NTDs along the Central Indian Ridge (CIR) from high resolution sidescan and bathymetry data. The CIR is an intermediate spreading ridge and within our study area between 18S and 21S, eight NTDs are identified, three of which are used for this study. The modelling results show a dominant component of along-axis offset for the stress field rotations. Model correlation and co-location with the CIR NTDs highlights important differences between the interpreted segment tips and the tips predicted by the mechanical models. We propose that segments interpreted from morphological and volcano-tectonic observations may overlook fundamental components of segment structure. The results indicate that morphologically defined segments are composed of an effective segment behaving at the scale of this study as cracks opening under a tensile stress in an elastic medium and a damage zone behaving inelastically between the effective segment tip and the NTD. The damage zone is broadly analogous to the process zone described in fracture mechanics. The damage zone if well developed is associated with crustal softening through significant tectonism in a region of high magnitude stresses ahead of the segment tip. One significant property of the damage zone is an increase in the permeability of the crust. We therefore propose that the damage zone coupled with a suitable heat supply from serpentinisation or along-axis transport of heat may be a favourable site for the development of hydrothermal systems

  8. Retrospective salt tectonics

    SciTech Connect

    Jackson, M.P.A.

    1996-12-31

    The conceptual breakthroughs in understanding salt tectonics can be recognized by reviewing the history of salt tectonics, which divides naturally into three parts: the pioneering era, the fluid era, and the brittle era. The pioneering era (1856-1933) featured the search for a general hypothesis of salt diapirism, initially dominated by bizarre, erroneous notions of igneous activity, residual islands, in situ crystallization, osmotic pressures, and expansive crystallization. Gradually data from oil exploration constrained speculation. The effects of buoyancy versus orogeny were debated, contact relations were characterized, salt glaciers were discovered, and the concepts of downbuilding and differential loading were proposed as diapiric mechanisms. The fluid era (1933-{approximately}1989) was dominated by the view that salt tectonics resulted from Rayleigh-Taylor instabilities in which a dense fluid overburden having negligible yield strength sinks into a less dense fluid salt layer, displacing it upward. Density contrasts, viscosity contrasts, and dominant wavelengths were emphasized, whereas strength and faulting of the overburden were ignored. During this era, palinspastic reconstructions were attempted; salt upwelling below thin overburdens was recognized; internal structures of mined diapirs were discovered; peripheral sinks, turtle structures, and diapir families were comprehended; flow laws for dry salt were formulated; and contractional belts on divergent margins and allochthonous salt sheets were recognized. The 1970s revealed the basic driving force of salt allochthons, intrasalt minibasins, finite strains in diapirs, the possibility of thermal convection in salt, direct measurement of salt glacial flow stimulated by rainfall, and the internal structure of convecting evaporites and salt glaciers. The 1980`s revealed salt rollers, subtle traps, flow laws for damp salt, salt canopies, and mushroom diapirs.

  9. Chronology and geochemistry of Mesozoic granitoids in the Bengbu area, central China: Constraints on the tectonic evolution of the eastern North China Craton

    NASA Astrophysics Data System (ADS)

    Yang, De-Bin; Xu, Wen-Liang; Wang, Qing-Hai; Pei, Fu-Ping

    2010-01-01

    We performed zircon U-Pb dating and analyses of major and trace elements, and Sr-Nd-Pb isotopes for granitoids in the Bengbu area, central China, with the aim of constraining the magma sources and tectonic evolution of the eastern North China Craton (NCC). The analyzed zircons show typical fine-scale oscillatory zoning, indicating a magmatic origin. Zircon U-Pb dating reveals granitoids of two ages: Late Jurassic and Early Cretaceous ( 206Pb/ 238U ages of 160 Ma and 130-110 Ma, respectively). The Late Jurassic rocks (Jingshan intrusion) consist of biotite-syenogranite, whereas the Early Cretaceous rocks (Huaiguang, Xilushan, Nushan, and Caoshan intrusions) are granodiorite, syenogranite, and monzogranite. The Late Jurassic biotite-syenogranites and Early Cretaceous granitoids have the following common geochemical characteristics: SiO 2 = 70.35-74.56 wt.%, K 2O/Na 2O = 0.66-1.27 (mainly < 1.0), and A/CNK = 0.96-1.06, similar to I-type granite. The examined rocks are characterized by enrichment in light rare earth elements, large ion lithophile elements, and U; depletion in heavy rare earth elements, Nb, and Ta; and high initial 87Sr/ 86Sr ratios (0.7081-0.7110) and low ɛNd ( t) values (- 14.40 to - 22.77), indicating a crustal origin. The occurrence of Neoproterozoic magmatic zircons (850 Ma) and inherited early Mesozoic (208-228 Ma) metamorphic zircons within the Late Jurassic biotite-syenogranites, together with the occurrence of Neoproterozoic magmatic zircons (657 and 759 Ma) and inherited early Mesozoic (206-231 Ma) metamorphic zircons within the Early Cretaceous Nushan and Xilushan granitoids, suggests that the primary magmas were derived from partial melting of the Yangtze Craton (YC) basement. In contrast, the occurrence of Paleoproterozoic and Paleoarchean inherited zircons within the Huaiguang granitoids indicates that their primary magmas mainly originated from partial melting of the NCC basement. The occurrence of YC basement within the lower

  10. Tectonic ancestry of central Montana and its influence on inversion tectonics

    SciTech Connect

    Woodward, L.A.

    1996-06-01

    Inversion tectonics, where structurally low areas become structurally high, has profound implications for hydrocarbon exploration. Effective exploration depends on understanding structures, timing, and controls on tectonic inversion. In central Montana tectonic inversion occurred three times in Phanerozoic time and reflects Precambrian tectonic trends. Westerly striking, steep foliation in Archean crystalline rocks defines the tectonic grain in basement exposures. The Helena embayment of the Middle Proterozoic Belt Basin formed an east-trending aulacogen extending into the craton in central Montana. Westerly trending fault-blocks of probable Late Proterozoic age formed within the embayment. The trough was tectonically inverted in the Devonian, but was depressed in the Carboniferous, accumulating major thicknesses of Madison Group and Big Snowy Group strata. Tectonic inversion again occurred with rise of the {open_quotes}Belt island{close_quotes} in the Jurassic. The trough was reactivated with a thick accumulation of lower Lower Cretaceous strata. Laramide (Late Cretaceous-early Tertiary) deformation resulted in tectonic inversion with rise of the Little Belt, Big Snowy, and related uplifts. Reactivation with reverse and strike-slip movement occurred on synsedimentary Proterozoic westerly trending normal faults that bounded the Helena embayment. Subsidence was probably related to crustal extension, whereas tectonic inversion and rise is inferred to be caused by crustal shortening. West-northwesterly trending en echelon folds that cross central Montana suggest major left shift. The Precambrian structural framework and fabric of the region thus appear to have had major influence on tectonic features that were multiply reactivated in Phanerozoic time.

  11. Preliminary results on the tectonic activity of the Ovacık Fault (Malatya-Ovacık Fault Zone, Turkey): Implications of the morphometric analyses

    NASA Astrophysics Data System (ADS)

    Yazıcı, Müge; Zabci, Cengiz; Sançar, Taylan; Sunal, Gürsel; Natalin, Boris A.

    2016-04-01

    The Anatolian 'plate' is being extruded westward relative to the Eurasia along two major tectonic structures, the North Anatolian and the East Anatolian shear zones, respectively making its northern and eastern boundaries. Although the main deformation is localized along these two structures, there is remarkable intra-plate deformation within Anatolia, especially which are characterized by NE-striking sinistral and NW-striking dextral strike-slip faults (Şengör et al. 1985). The Malatya-Ovacık Fault Zone (MOFZ) and its northeastern member, the Ovacık Fault (OF), is a one of the NE-striking sinistral strike slip faults in the central 'ova' neotectonic province of Anatolia, located close to its eastern boundary. Although this fault zone is claimed to be an inactive structure in some studies, the recent GPS measurements (Aktuǧ et al., 2013) and microseismic activity (AFAD, 2013) strongly suggest the opposite. In order to understand rates and patterns of vertical ground motions along the OF, we studied the certain morphometric analyses such as hypsometric curves and integrals, longitudinal channel profiles, and asymmetry of drainage basins. The Karasu (Euphrates) and Munzur rivers form the main drainage systems of the study area. We extracted all drainage network from SRTM-based Digital Elevation Model with 30 m ground pixel resolution and totally identified 40 sub-drainage basins, which are inhomogeneously distributed to the north and to the south of the OF. Most of these basins show strong asymmetry, which are mainly tilted to SW. The asymmetry relatively decreases from NE to SW in general. The only exception is at the margins of the Ovacık Basin (OB), where almost the highest asymmetry values were calculated. On the other hand, the characteristics of hypsometric curves and the calculated hypsometric integrals do not show the similar systematic spatial pattern. The hypsometric curves with convex-shaped geometry, naturally indicating relatively young morphology

  12. Preliminary results on the tectonic activity of the Ovacık Fault (Malatya-Ovacık Fault Zone, Turkey): Implications of the morphometric analyses

    NASA Astrophysics Data System (ADS)

    Yazıcı, Müge; Zabci, Cengiz; Sançar, Taylan; Sunal, Gürsel; Natalin, Boris A.

    2016-04-01

    The Anatolian 'plate' is being extruded westward relative to the Eurasia along two major tectonic structures, the North Anatolian and the East Anatolian shear zones, respectively making its northern and eastern boundaries. Although the main deformation is localized along these two structures, there is remarkable intra-plate deformation within Anatolia, especially which are characterized by NE-striking sinistral and NW-striking dextral strike-slip faults (Şengör et al. 1985). The Malatya-Ovacık Fault Zone (MOFZ) and its northeastern member, the Ovacık Fault (OF), is a one of the NE-striking sinistral strike slip faults in the central 'ova' neotectonic province of Anatolia, located close to its eastern boundary. Although this fault zone is claimed to be an inactive structure in some studies, the recent GPS measurements (Aktuǧ et al., 2013) and microseismic activity (AFAD, 2013) strongly suggest the opposite. In order to understand rates and patterns of vertical ground motions along the OF, we studied the certain morphometric analyses such as hypsometric curves and integrals, longitudinal channel profiles, and asymmetry of drainage basins. The Karasu (Euphrates) and Munzur rivers form the main drainage systems of the study area. We extracted all drainage network from SRTM-based Digital Elevation Model with 30 m ground pixel resolution and totally identified 40 sub-drainage basins, which are inhomogeneously distributed to the north and to the south of the OF. Most of these basins show strong asymmetry, which are mainly tilted to SW. The asymmetry relatively decreases from NE to SW in general. The only exception is at the margins of the Ovacık Basin (OB), where almost the highest asymmetry values were calculated. On the other hand, the characteristics of hypsometric curves and the calculated hypsometric integrals do not show the similar systematic spatial pattern. The hypsometric curves with convex-shaped geometry, naturally indicating relatively young morphology

  13. Preliminary results of systematic sampling of gas manifestations in geodynamically active areas of Greece

    NASA Astrophysics Data System (ADS)

    Daskalopoulou, Kyriaki; D'Alessandro, Walter; Calabrese, Sergio; Kyriakopoulos, Konstantinos

    2016-04-01

    Greece is located on a convergent plate boundary comprising the subduction of the African Plate beneath the Eurasian, while the Arabian plate approaches the Eurasian in a northwestward motion. It is considered to be one of the most tectonically active regions of Earth with a complex geodynamic setting, deriving from a long and complicated geological history. Due to this specific geological background, conditions for the formation of many thermal springs are favoured. In the past years, almost all the already known sites of degassing (fumaroles, soil gases, mofettes, gas bubbling in cold and thermal waters) located in the Hellenic area were sampled at least one time. Collected samples were analysed for their chemical (He, Ne, Ar, O2, N2, H2, H2S, CO, CH4 and CO2) and isotopic composition (He, C and N). Some of these sites have been selected for systematic sampling. Four of them have records longer than 10 years with tens of samplings also considering some literature data. Two of the sites are located in active volcanic areas (Santorini and Nisyros) while the other two are close to actively spreading graben structures with intense seismic activity (Gulf of Korinth and Sperchios basin). Results allowed to define long term background values and also some interesting variation related to seismic or volcanic activity.

  14. Incipient mantle delamination, active tectonics and crustal thickening in Northern Morocco: Insights from gravity data and numerical modeling

    NASA Astrophysics Data System (ADS)

    Baratin, Laura-May; Mazzotti, Stéphane; Chéry, Jean; Vernant, Philippe; Tahayt, Abdelilah; Mourabit, Taoufik

    2016-11-01

    The Betic-Rif orocline surrounding the Alboran Sea, the westernmost tip of the Mediterranean Sea, accommodates the NW-SE convergence between the Nubia and Eurasia plates. Recent GPS observations indicate a ∼4 mm/yr SW motion of the Rif Mountains, relative to stable Nubia, incompatible with a simple two-plate model. New gravity data acquired in this study define a pronounced negative Bouguer anomaly south of the Rif, interpreted as a ∼40 km-thick crust in a state of non-isostatic equilibrium. We study the correlation between these present-day kinematic and geodynamic processes using a finite-element code to model in 2-D the first-order behavior of a lithosphere affected by a downward normal traction (representing the pull of a high-density body in the upper mantle). We show that intermediate viscosities for the lower crust and uppermost mantle (1021-1022Pas) allow an efficient coupling between the mantle and the base of the brittle crust, thus enabling (1) the conversion of vertical movement, resulting from the downward traction, to horizontal movement and (2) shortening in the brittle upper crust. Our results show that incipient delamination of the Nubian continental lithosphere, linked to slab pull, can explain the present-day abnormal tectonics, contribute to the gravity anomaly observed in northern Morocco, and give insight into recent tectonics in the Western Mediterranean region.

  15. A quantitative geomorphological approach to constraining the volcanic and tectonic evolution of the active Dabbahu rift segment, Afar, Ethiopia.

    NASA Astrophysics Data System (ADS)

    Medynski, Sarah; Pik, Raphaël; Burnard, Peter; Vye-Brown, Charlotte; Blard, Pierre-Henri; France, Lydéric; Dumont, Stéphanie; Grandin, Raphaël; Schimmelpfennig, Irene; Benedetti, Lucilla; Ayalew, Dereje; Yirgu, Gezahegn

    2013-04-01

    In the Afar depression (Ethiopia), extension is organised along rift segments that morphologically resemble oceanic rifts. Segmentation results from interactions between dyke injection and volcanism, as observed during the well-documented 2005 rifting event on the Dabbahu rift segment. This tectono-volcanic crisis was observed in detail via remote sensing techniques, providing invaluable information on the present-day tectonic - magmatic interplay during a sequence of dyke intrusions. However, lack of data remains on timescales of 1 to 100 kyr, the period over which the main morphology of the rift is acquired. The Dabbahu rift segment represents an ideal natural laboratory to study the evolution of rift morphology as a response to volcanic and tectonic influences. We use cosmogenic nuclides (3He and 36Cl) to determine the ages of young (<100 kyr) lava flows and to date the initiation and movement of fault scarps, which cut the lavas. Where possible, we analysed vertical profiles along fault scarps, in an attempt to distinguish individual tectonic events that offset the scarp, estimate their amplitudes and date the recurrence intervals. These geochronological constraints, combined with major & trace element compositions, field mapping and digital mapping (Landsat, ASTER and SPOT imagery), provide valuable insights on the magmatic and tectonic history of the segment. The results show that over the last 100 ka, the northern part of the Dabbahu segment was supplied by at least two different magma reservoirs, which can be identified from their distinctive chemistries. The main reservoir is located beneath Dabbahu volcano at the northern tip of the rift segment, and has been supplied with magma for at least 72 ka. The second reservoir is located further south on the rift axis and corresponds to the current mid-segment magma chamber, which was responsible for the 2005 rifting episode. Two magmatic cycles linked to the Dabbahu magma chamber were recorded, lasting 20-30 kyr

  16. The interpretation of crustal dynamics data in terms of plate interactions and active tectonics of the Anatolian plate and surrounding regions in the Middle East

    NASA Technical Reports Server (NTRS)

    Toksoz, M. Nafi; Reilinger, Robert

    1992-01-01

    A detailed study was made of the consequences of the Arabian plate convergence against Eurasia and its effects on the tectonics of Anatolia and surrounding regions of the eastern Mediterranean. A primary source of information is time rates of change of baseline lengths and relative heights determined by repeated SLR measurements. These SLR observations are augmented by a network of GPS stations in Anatolia, Aegea, and Greece, established and twice surveyed since 1988. The existing SLR and GPS networks provide the spatial resolution necessary to reveal the details of ongoing tectonic processes in this area of continental collision. The effort has involved examining the state of stress in the lithosphere and relative plate motions as revealed by these space based geodetic measurements, seismicity, and earthquake mechanisms as well as the aseismic deformations of the plates from conventional geodetic data and geological evidence. These observations are used to constrain theoretical calculations of the relative effects of: (1) the push of the Arabian plate; (2) high topography of Eastern Anatolia; (3) the geometry and properties of African-Eurasian plate boundary; (4) subduction under the Hellenic Arc and southwestern Turkey; and (5) internal deformation and rotation of the Anatolian plate.

  17. Fault-based PSHA of an active tectonic region characterized by low deformation rates: the case of the Lower Rhine Graben

    NASA Astrophysics Data System (ADS)

    Vanneste, Kris; Vleminckx, Bart; Camelbeeck, Thierry

    2016-04-01

    The Lower Rhine Graben (LRG) is one of the few regions in intraplate NW Europe where seismic activity can be linked to active faults, yet probabilistic seismic hazard assessments of this region have hitherto been based on area-source models, in which the LRG is modeled as a single or a small number of seismotectonic zones with uniform seismicity. While fault-based PSHA has become common practice in more active regions of the world (e.g., California, Japan, New Zealand, Italy), knowledge of active faults has been lagging behind in other regions, due to incomplete tectonic inventory, low level of seismicity, lack of systematic fault parameterization, or a combination thereof. The past few years, efforts are increasingly being directed to the inclusion of fault sources in PSHA in these regions as well, in order to predict hazard on a more physically sound basis. In Europe, the EC project SHARE ("Seismic Hazard Harmonization in Europe", http://www.share-eu.org/) represented an important step forward in this regard. In the frame of this project, we previously compiled the first parameterized fault model for the LRG that can be applied in PSHA. We defined 15 fault sources based on major stepovers, bifurcations, gaps, and important changes in strike, dip direction or slip rate. Based on the available data, we were able to place reasonable bounds on the parameters required for time-independent PSHA: length, width, strike, dip, rake, slip rate, and maximum magnitude. With long-term slip rates remaining below 0.1 mm/yr, the LRG can be classified as a low-deformation-rate structure. Information on recurrence interval and elapsed time since the last major earthquake is lacking for most faults, impeding time-dependent PSHA. We consider different models to construct the magnitude-frequency distribution (MFD) of each fault: a slip-rate constrained form of the classical truncated Gutenberg-Richter MFD (Anderson & Luco, 1983) versus a characteristic MFD following Youngs

  18. Tectonic controls on the morphometry of alluvial fans around Danehkhoshk anticline, Zagros, Iran

    NASA Astrophysics Data System (ADS)

    Bahrami, Shahram

    2013-01-01

    Alluvial fans are important landforms where their morphology and morphometry reflect changes in tectonic, climate, base level, and drainage basin characteristics. Along the margins of tectonically active mountain ranges like the Zagros Mountains, alluvial fans are generally assumed to act as useful landforms for identifying the level of tectonic activity. The purpose of this paper is to evaluate the relationship between active tectonics and morphometric characteristics of alluvial fans around Danehkhoshk anticline in the Simply Folded Belt of Zagros. Morphometric characteristics of alluvial fans, such as area (FA), slope (SF) length of base (BF), width/length ratio (W/L), radius (R), sweep angle (SA) and entrenchment (E) as well as valley floor width-to-height ratio (Vf) and strata dips of anticline limbs (DAL), were measured. The study area was sub-divided into eight tectonic zones and then the mean values of the above-mentioned parameters were calculated in each zone. Result reveals that values of SA, BF and E are directly proportional to DAL. The poor relationships between catchment characteristics (slope and area) and fan parameters are probably due to extensive karstic landforms of catchments having complex hydrologic systems and, hence, result in complex catchment/fan relations. The highly entrenched fans with high sweep angles and long bases are characteristic of tectonically active fronts of Danehkhoshk anticline, having V-shaped valleys (higher Vf values), steep triangular facets and more rotated limbs (higher DAL values). Apart from the tectonic control on fan development, the fan head entrenchment and negative accumulation spaces on most alluvial fans can be attributed to decreased sediment load and discharge the drier the present-day climate regime.

  19. Geochemistry of the Jurassic and Upper Cretaceous shales from the Molango Region, Hidalgo, eastern Mexico: Implications for source-area weathering, provenance, and tectonic setting

    NASA Astrophysics Data System (ADS)

    Armstrong-Altrin, John S.; Nagarajan, Ramasamy; Madhavaraju, Jayagopal; Rosalez-Hoz, Leticia; Lee, Yong Il; Balaram, Vysetti; Cruz-Martínez, Adriana; Avila-Ramírez, Gladis

    2013-04-01

    This study focuses on the Jurassic (Huayacocotla and Pimienta Formations) and Upper Cretaceous (Méndez Formation) shales from the Molango Region, Hidalgo, Mexico. In this article, we discuss the mineralogy, major, and trace element geochemistry of the Mesozoic shales of Mexico. The goal of this study is to constrain the provenance of the shales, which belong to two different periods of the Mesozoic Era and to understand the weathering conditions and tectonic environments of the source region.

  20. Recent tectonics of East (Iranian) Azerbaijan from stress state reconstructions

    NASA Astrophysics Data System (ADS)

    Zamani G., Behzad; Masson, Frédéric

    2014-01-01

    Iranian (East) Azerbaijan (E-Azerbaijan), in northwestern Iran, is characterized by relatively complex active tectonics. The area is shaped like a lozenge and is bordered by strike-slip faults. This region includes three fold and thrust belts, the Arasbaran, Ghoshe Dagh and Bozkosh mountain ranges, and includes a set of N-S trending compressive thrusts and folds and a set of E-W trending compressive structures.

  1. NASA's Spaceliner 100 Investment Area Technology Activities

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe; Lyles, Garry M. (Technical Monitor)

    2001-01-01

    NASA's has established long term goals for access-to-space. The third generation launch systems are to be fully reusable and operational around 2025. The goals for the third generation launch system are to reduce cost by a factor of 100 and improve safety by a factor of 10,000 over current conditions. The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop space transportation technologies. Within ASTP, under the Spaceliner100 Investment Area, third generation technologies are being pursued in the areas of propulsion, airframes, integrated vehicle health management (IVHM), launch systems, and operations and range. The ASTP program will mature these technologies through ground system testing. Flight testing where required, will be advocated on a case by case basis.

  2. NASA's Spaceliner Investment Area Technology Activities

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe; Lyles, Garry M. (Technical Monitor)

    2001-01-01

    NASA's has established long term goals for access-to-space. The third generation launch systems are to be fully reusable and operational around 2025. The goals for the third generation launch system are to significantly reduce cost and improve safety over current conditions. The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville, AL has the agency lead to develop space transportation technologies. Within ASTP, under the Spaceliner Investment Area, third generation technologies are being pursued in the areas of propulsion, airframes, integrated vehicle health management (IVHM), avionics, power, operations, and range. The ASTP program will mature these technologies through both ground and flight system testing. The Spaceliner Investment Area plans to mature vehicle technologies to reduce the implementation risks for future commercially developed reusable launch vehicles (RLV). The plan is to substantially increase the design and operating margins of the third generation RLV (the Space Shuttle is the first generation) by incorporating advanced technologies in propulsion, materials, structures, thermal protection systems, avionics, and power. Advancements in design tools and better characterization of the operational environment will allow improvements in design margins. Improvements in operational efficiencies will be provided through use of advanced integrated health management, operations, and range technologies. The increase in margins will allow components to operate well below their design points resulting in improved component operating life, reliability, and safety which in turn reduces both maintenance and refurbishment costs. These technologies have the potential of enabling horizontal takeoff by reducing the takeoff weight and achieving the goal of airline-like operation. These factors in conjunction with increased flight rates from an expanding market will result in significant improvements in safety

  3. Active tectonics of the western tethyan himalaya above the underthrusting indian plate: The upper sutlej river basin as a pull-apart structure

    NASA Astrophysics Data System (ADS)

    Ni, James; Barazangi, Muawia

    1985-03-01

    Fault-bounded blocks and structural elements were mapped in the eastern Ladakh-Spiti and upper Sutlej River Basin located within the Tethyan Himalaya and to the southwest of the Karakorum fault zone mainly using LANDSAT Multispectral Scanner (MSS) band 5, band 7 (near-infrared) images with detailed analysis of smaller areas by interactive digital processing of false color images, and Returned Beam Vidicon (RBV) imagery in conjunction with available topographical, geological and seismological data. For the first time the Leo Pargil Horst and other nearby fault-bounded blocks located at the northwestern end of the upper Setlej River Basin were clearly revealed on the LANDSAT color composites. Shallow crustal seismicity is systematically related to the NNE-trending and N-trending normal faults of the Leo Pargil and nearby regions. Some of the aftershocks of the Kinnaur earthquake of January 19,1975 ( Ms = 6.8), appear to be associated with movement along the NNE-trending westbound fault of the Leo Pargil Horst and the nearby Kaurik-Chango fault. The main shock, however, is teleseismically located at about 30 km to the northwest of the Kaurik-Chango fault. Fault plane solutions of the main shock and two aftershocks indicate a large component of normal faulting. In map view, the upper Sutlej River Basin has an approximately rhomboidal shape and is located to the southwest of the Karakorum fault system. We suggest that this basin is a pull-apart between the NW-SE oriented, right-lateral, strike-slip Karakorum fault system and the high-angle faults near the southern boundary of the Tethyan Himalaya. The Leo Pargil Horst is the northwestern bounding fault block of this pull-apart. The active tectonic features in this part of the Tethyan Himalaya appear to reflect right-shear within the crust, and this is probably a consequence of oblique underthrusting of the Indian continental plate beneath the western Himalaya and southwestern Tibet during the Neogene and Quaternary

  4. Late Pleistocene-Holocene uplift driven terrace formation and climate-tectonic interplay from a seismically active intraplate setting: An example from Kachchh, Western India

    NASA Astrophysics Data System (ADS)

    Prizomwala, S. P.; Das, Archana; Chauhan, G.; Solanki, T.; Basavaiah, N.; Bhatt, Nilesh; Thakkar, M. G.; Rastogi, B. K.

    2016-07-01

    terrace, we reported a minimum uplift rate of 1.04 mm/a for the eastern KMF during the Late Pleistocene-Holocene period, hinting seismically active nature of the KMF during this period. The terrace formation in the eastern Northern Hill Range is mostly regulated by tectonic uplifts along the KMF.

  5. Geomorphic evidence of active faults growth in the Norcia seismic area (central Apennines, Italy)

    NASA Astrophysics Data System (ADS)

    Materazzi, Marco; Aringoli, Domenico; Farabollini, Piero; Giacopetti, Marco; Pambianchi, Gilberto; Tondi, Emanuele; Troiani, Francesco

    2016-04-01

    Fault-growth by segment linkage is one of the fundamental processes controlling the evolution, in both time and the space, of fault systems. In fact, step-like trajectories shown by length-displacement diagrams for individual fault arrays suggest that the development of evolved structures result by the linkage of single fault segments. The type of interaction between faults and the rate at which faults reactivate not only control the long term tectonic evolution of an area, but also influence the seismic hazard, as earthquake recurrence intervals tend to decrease as fault slip rate increase. The use of Geomorphological investigations represents an important tool to constrain the latest history of active faults. In this case, attention has to be given to recognize morphostructural, historical, environmental features at the surface, since they record the long-term seismic behavior due to the fault growth processes (Tondi and Cello, 2003). The aim of this work is to investigate the long term morphotectonic evolution of a well know seismic area in the central Apennines: the Norcia intramontane basin (Aringoli et al., 2005). The activity of the Norcia seismic area is characterized by moderate events and by strong earthquakes with maximum intensities of X-XI degrees MCS and equivalent magnitudes around 6.5±7.0 (CPTI, 2004). Based on the morphostructural features as well as on the historical seismicity of the area, we may divide the Norcia seismic area into three minor basins roughly NW-SE oriented: the Preci sub-basin in the north; the S. Scolastica and the Castel S. Maria sub-basins in the south. The wider basin (S. Scolastica) is separated from the other two by ridges transversally oriented with respect the basins themselves; they are the geomorphological response to the tectonic deformation which characterizes the whole area. Other geomorphological evidences of tectonic activity are represented by deformation of old summit erosional surfaces, hydrographic network

  6. Using Grand Challenges For Innovative Teaching in Structural Geology, Geophysics, and Tectonics

    NASA Astrophysics Data System (ADS)

    McDaris, J. R.; Tewksbury, B. J.; Wysession, M. E.

    2012-12-01

    An innovative approach to teaching involves using the "Big Ideas" or "Grand Challenges" of a field, as determined by the research community in that area, as the basis for classroom activities. There have been several recent efforts in the areas of structural geology, tectonics, and geophysics to determine these Grand Challenges, including the areas of seismology ("Seismological Grand Challenges in Understanding Earth's Dynamic Systems"), mineral physics ("Unlocking the Building Blocks of the Planet"), EarthScope-related science ("Unlocking the Secrets of the North American Continent: An EarthScope Science Plan for 2010-2020"), and structural geology and tectonics (at the Structural Geology and Tectonics Forum held at Williams College in June, 2012). These research community efforts produced frameworks of the essential information for their fields with the aim of guiding future research. An integral part of this, however, is training the next generation of scientists, and using these Big Ideas as the basis for course structures and activities is a powerful way to make this happen. When activities, labs, and homeworks are drawn from relevant and cutting-edge research topics, students can find the material more fascinating and engaging, and can develop a better sense of the dynamic process of scientific discovery. Many creative ideas for incorporating the Grand Challenges of structural geology, tectonics, and geophysics in the classroom were developed at a Cutting Edge workshop on "Teaching Structural Geology, Geophysics, and Tectonics in the 21st Century" held at the University of Tennessee in July, 2012.

  7. 50 CFR 218.120 - Specified activity and geographical area.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Activities Area (GoA TMAA) § 218.120 Specified activity and geographical area. (a) Regulations in this... Alaska Temporary Maritime Activities Area (GoA TMAA) (as depicted in Figure 1-1 in the Navy's application for GoA TMAA), which is bounded by a hexagon with the following six corners: 57°30′ N. lat., 141°30′...

  8. Holocene Tectonic and Sedimentary Evolution of Coastal San Diego

    NASA Astrophysics Data System (ADS)

    Maloney, J. M.; Driscoll, N. W.; Brothers, D. S.; Babcock, J. M.; Kent, G.

    2010-12-01

    The shelf and nearshore region of San Diego, California, between La Jolla cove in the north and the U.S.- Mexico border in the south, is an important ecological and economic resource. It contains two of the largest kelp forests in southern California and lies offshore miles of popular beaches. Understanding the interplay between tectonic and sedimentary processes in this area is critical because it will allow us to assess how other forcing functions such as the rapid sea level rise (2 - 3 mm/yr) and predicted climate change associated with global warming are impacting the kelp and nearshore environments. The fault architecture and sedimentary deposits offshore San Diego have been mapped using high-resolution seismic CHIRP profiling. The mapped area lies within the inner California Continental Borderland (CCB), which is characterized by a system of basins and ridges and extensive strike-slip faulting. The CHIRP data clearly images several splays of the Coronado Bank Fault Zone (CBFZ), a major fault in the area, which show recent activity in the upper 30 m of sediment with the most recent deformation at ~4 m below seafloor. Several sediment packages as deep as 50 m below the seafloor are imaged and place important constraints on tectonic deformation and sediment dispersal in the region as well as the earthquake recurrence interval on the CBFZ. Exposed and buried wavecut terraces identified on numerous CHIRP profiles, which can be correlated to terraces mapped regionally, provide insight into tectonic uplift rates and sea-level fluctuations. Finally, the extensive kelp forests offshore Mount Soledad and Point Loma occur where hardgrounds are exposed at the seafloor as a consequence of tectonic uplift. High resolution mapping offshore San Diego is providing new insight into the complex interplay between tectonics, sedimentation, and biology in this ecologically diverse region.

  9. Active Pacific North America Plate boundary tectonics as evidenced by seismicity in the oceanic lithosphere offshore Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Hauksson, Egill; Kanamori, Hiroo; Stock, Joann; Cormier, Marie-Helene; Legg, Mark

    2014-03-01

    Pacific Ocean crust west of southwest North America was formed by Cenozoic seafloor spreading between the large Pacific Plate and smaller microplates. The eastern limit of this seafloor, the continent-ocean boundary, is the fossil trench along which the microplates subducted and were mostly destroyed in Miocene time. The Pacific-North America Plate boundary motion today is concentrated on continental fault systems well to the east, and this region of oceanic crust is generally thought to be within the rigid Pacific Plate. Yet, the 2012 December 14 Mw 6.3 earthquake that occurred about 275 km west of Ensenada, Baja California, Mexico, is evidence for continued tectonism in this oceanic part of the Pacific Plate. The preferred main shock centroid depth of 20 km was located close to the bottom of the seismogenic thickness of the young oceanic lithosphere. The focal mechanism, derived from both teleseismic P-wave inversion and W-phase analysis of the main shock waveforms, and the 12 aftershocks of M ˜3-4 are consistent with normal faulting on northeast striking nodal planes, which align with surface mapped extensional tectonic trends such as volcanic features in the region. Previous Global Positioning System (GPS) measurements on offshore islands in the California Continental Borderland had detected some distributed Pacific and North America relative plate motion strain that could extend into the epicentral region. The release of this lithospheric strain along existing zones of weakness is a more likely cause of this seismicity than current thermal contraction of the oceanic lithosphere or volcanism. The main shock caused weak to moderate ground shaking in the coastal zones of southern California, USA, and Baja California, Mexico, but the tsunami was negligible.

  10. Guide to good practices for control area activities

    SciTech Connect

    1998-12-01

    This Guide to Good Practices is written to enhance understanding of, and provide direction for, Control Area Activities, Chapter III of Department of Energy (DOE) Order 5480.19, Conduct of Operations Requirements for DOE Facilities. The practices in this guide should be considered for controlling the activities in control areas. Contractors are advised to adopt procedures that meet the intent of DOE Order 5480.19. Control Area Activities is an element of an effective Conduct of Operations program. The complexity and array of activities performed in DOE facilities dictate the necessity for maintaining a formal environment in operational control areas to promote safe and efficient operations.

  11. Tectonic features on Saturns satellites Dione and Rhea: Morphology and stratigraphy derived from Cassini ISS images

    NASA Astrophysics Data System (ADS)

    Wagner, R. J.; Neukum, G.; Stephan, K.; Giese, B.; Roatsch, T.; Wolf, U.; Porco, C. C.

    2009-04-01

    Introduction: The second- and fourth-largest satellites of Saturn, Rhea (1528 km in diameter) and Dione (1124 km), harbor old, densely cratered surfaces but also show evidence of resurfacing through tectonism in the images taken by the two ISS cameras aboard the Cassini spacecraft since July 2004. On Dione, tectonic features are more widespread than on Rhea implying that geologic activity has been going on for a longer time, whereas on Rhea tectonic activity may have ceased early in its history. The tectonic inventory of both satellites incorporates (a) troughs (graben), (b) scarps, (c) ridges, (d) lineaments, and (e) plateaus on Dione. Procedure: In this paper we focus on the stratigraphic sequence of events which created these tectonic landforms, independent of specific stress origins which are the topic of further work. Our investigation is based on the global ISS image coverage at regional (150 - 500 m/pxl), and, for selected target areas, at high-resolution scale (< 50 m/pxl). Relative ages of tectonic landforms are constrained by (1) cross-cutting relationships, (2) by their degree of degradation, (3) and by their superimposed crater frequency. On Dione, the image resolutions are sufficient to examine stratigraphic relationships between tectonic features while on Rhea the areas affected by tectonism could not yet be observed so far at regional or high resolution. Stratigraphy: On both satellites, densely cratered plains are the dominant geologic units with inferred high ages of ~ 3 - 4.2 Gyr from cratering chronology models. Degraded, densely cratered graben in the high northern and southern latitudes on Dione were formed early in its history. On Rhea, ridges seen in stereo data also appear to be rather old features. Troughs and graben on Rhea's trailing hemisphere could be old, but further regional- and high-resolution imaging is needed for detailed investigations. On Dione's trailing hemisphere, a stratigraphic sequence of horsts, graben and scarps has been

  12. Geodynamic significance of the TRM segment in the East African Rift (W-Tanzania): Active tectonics and paleostress in the Ufipa plateau and Rukwa basin

    NASA Astrophysics Data System (ADS)

    Delvaux, D.; Kervyn, F.; Macheyeki, A. S.; Temu, E. B.

    2012-04-01

    The Tanganyika-Rukwa-Malawi (TRM) rift segment in western Tanzania is a key sector for understanding the opening dynamics of the East African rift system (EARS). In an oblique opening model, it is considered as a dextral transfer fault zone that accommodates the general opening of the EARS in an NW-SE direction. In an orthogonal opening model, it accommodates pure dip-slip normal faulting with extension orthogonal to the rift segments and a general E-W extension for the entire EARS. The central part of the TRM rift segment is well exposed in the Ufipa plateau and Rukwa basin, within the Paleoproterozoic Ubende belt. It is also one of the most seismically active regions of the EARS. We investigated the active tectonic architecture and paleostress evolution of the Ufipa plateau and adjacent Rukwa basin and in order to define their geodynamic role in the development of the EARS and highlight their pre-rift brittle tectonic history. The active fault architecture, fault-kinematic analysis and paleostress reconstruction show that the recent to active fault systems that control the rift structure develop in a pure extensional setting with extension direction orthogonal to the trend of the TRM segment. Two pre-rift brittle events are evidenced. An older brittle thrusting is related to the interaction between the Bangweulu block and the Tanzanian craton during the late Pan-African (early Paleozoic). It was followed by a transpressional inversion during the early Mesozoic. This inversion stage is the best expressed in the field and caused dextral strike-slip faulting along the fault systems that now control the major rift structures. It has been erroneously interpreted as related to the late Cenozoic EARS which instead is characterized by pure normal faulting (our third and last stress stage).

  13. Remedial activities effectiveness verification in tailing areas.

    PubMed

    Kluson, J; Thinova, L; Neznal, M; Svoboda, T

    2015-06-01

    The complex radiological study of the basin of sludge from the uranium ore mining and preprocessing was done. Air kerma rates (including its spectral analysis) at the reference height of 1 m above ground over the whole area were measured and radiation fields mapped during two measuring campaigns (years 2009 and 2014). K, U and Th concentrations in sludge and concentrations in depth profiles (including radon concentration and radon exhalation rates) in selected points were determined using gamma spectrometry for in situ as well as laboratory samples measurement. Results were used for the analysis, design evaluation and verification of the efficiency of the remediation measures. Efficiency of the sludge basin covering by the inert material was modelled using MicroShield code.

  14. Active tectonics on Deception Island (West-Antarctica): A new approach by using the fractal anisotropy of lineaments, fault slip measurements and the caldera collapse shape

    USGS Publications Warehouse

    Pérez-López, R.; Giner-Robles, J.L.; Martínez-Díaz, J.J.; Rodríguez-Pascua, M.A.; Bejar, M.; Paredes, C.; González-Casado, J.M.

    2007-01-01

    The tectonic field on Deception Island (South Shetlands, West Antarctica) is determined from structural and fractal analyses. Three different analyses are applied to the study of the strain and stress fields in the area: (1) field measurements of faults (strain analysis), (2) fractal geometry of the spatial distribution of lineaments and (3) the caldera shape (stress analyses). In this work, the identified strain field is extensional with the maximum horizontal shortening trending NE-SW and NW-SE. The fractal technique applied to the spatial distribution of lineaments indicates a stress field with SHMAX oriented NE-SW. The elliptical caldera of Deception Island, determined from field mapping, satellite imagery, vents and fissure eruptions, has an elongate shape and a stress field with SHMAX trending NE-SW.

  15. The tectonics of icy satellites

    NASA Astrophysics Data System (ADS)

    Murchie, S. L.

    The formation of tectonic structures on icy satellites may have resulted from one or more of several geologic processes: global volume change due to internal temperature change, H2O-ice phase changes, or ice-silicate differentiation; mantle convection driven by thermal or compositional heterogeneities; tidal deformation; and impact-related processes including formation of fracture systems, seismic disruption of areas antipodal to impact sites, basin collapse, and global reorientation. Observed tectonic structures and their associated volcanic deposits are classified herein into six basic assemblages: (1) pervasive troughs and scarps occurring at globally coherent orientations; (2) throughgoing troughs and bands of troughs, generally associated with volcanic materials; (3) linear to curvilinear ridges; (4) volcanically modified systems of concentric and radial scarps and furrows; (5) regional volcanic and tectonic centers; and (6) grooved terrain intimately associated with light-colored volcanic deposits. Comparison of these assemblages with predicted manifestations of different geologic processes may lead to some understanding of the relationship of volcanic and tectonic features to the endogenic and exogenic processes that have affected icy satellites.

  16. Geomorphology, tectonics, and exploration

    NASA Technical Reports Server (NTRS)

    Sabins, F. F., Jr.

    1985-01-01

    Explorationists interpret satellite images for tectonic features and patterns that may be clues to mineral and energy deposits. The tectonic features of interest range in scale from regional (sedimentary basins, fold belts) to local (faults, fractures) and are generally expressed as geomorphic features in remote sensing images. Explorationists typically employ classic concepts of geomorphology and landform analysis for their interpretations, which leads to the question - Are there new and evolving concepts in geomorphology that may be applicable to tectonic analyses of images?

  17. Tectonic and stratigraphic evolution in South Alboran Sea (Morocco)

    NASA Astrophysics Data System (ADS)

    D'Acremont, E.; Gorini, C.; El Abbassi, M.; Farran, M.; Leroy, S.; Mercier De Lepinay, B. F.; Migeon, S.; Poort, J.; Ammar, A.; Smit, J.; Ercilla, G.; Alonso, B.; Scientific Team of the Marlboro project

    2011-12-01

    The Alboran Basin, in western Mediterranean, concentrates on a relatively small surface and densely-populated, a large structural complexity linked to seismic activity with recurrent mass-transport deposits that may trigger tsunamis. It was formed by Oligo-Miocene extension while tectonic inversion occurred since the Late Miocene (Tortonian) due to the African-European collision. This North-South compression produces a conjugated fault system located in the central area from Al Hoceima to Andalusia. Numerous instabilities are linked to the recent and present-day seismic activity and show the link between seismicity and erosion-sedimentation processes. On the Andalusia margin the active structures have been identified and recently mapped in detail by using MBES data (including backscatter), and high-resolution seismic data. Such detailed studies have not yet been carried out on the Moroccan margin. The Marlboro-1 oceanographic cruise (R/V Côtes de la Manche, July 2011) has imaged and constrained active structures and associated sedimentary systems through seismic reflection data (MCS). The Xauen/Tofino banks (growth folds), the Alboran Ridge, and the Al Hoceima basin offshore Morocco have been selected because they constitute key-study areas that record a complete deformation history since the Tortonian. Active features including faults, growth folds, channels, mass transport deposits, contourites and volcanoes has provided first order tectonic and sedimentary markers of the basin's evolution. A high chrono-stratigraphical resolution will constitute the basis for reconstructing the evolution of this tectonically active area marked by strong seismic activity. The Marlboro-1 cruise will allow determining key-study area of the Marlboro-2 cruise scheduled for 2012 (R/V Téthys-II, CNFC Call). These cruises should allow for the acquisition of data necessary to characterize basin morphology, active tectonic and sedimentary structures and also make the link with existing

  18. Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: observations in groundwaters along the San Andreas Fault

    USGS Publications Warehouse

    Deeds, Daniel A.; Kulongoski, Justin T.; Muhle, Jens; Weiss, Ray F.

    2015-01-01

    Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge (CreCre; ∼30 fmol kg−1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1–9 times CreCre), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10–980 times CreCre) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20–100 km) suggests that the SAFS potentially emits (0.3–1)×10−1 kg(0.3–1)×10−1 kg CF4 yr−1 to the Earth's surface. For comparison, the chemical weathering of ∼7.5×104 km2∼7.5×104 km2 of granitic rock in California is estimated to release (0.019–3.2)×10−1 kg(0.019–3.2)×10−1 kg CF4 yr−1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial–interglacial transitions.

  19. Tectonics on Triton

    NASA Astrophysics Data System (ADS)

    Croft, Steven K.

    1993-03-01

    Tectonic features on Triton have been mapped as part of a larger study of the geology of Triton. Few purely tectonic structures are found on Triton: some grabens and possibly some compressive ridges. However, most of the other structures seen (primarily cryovolcanic in origin) exhibit tectonic control. A regional tectonic network has the following dominant orientations: N-S, E-W, NE-SW, and NW-SE. Most of the orientations are consistent with tidal deformations related to Triton's decreasing orbital radius. Localized quasi-concentric patterns may be due to interior processes such as mantle plumes.

  20. Tectonics on Triton

    NASA Technical Reports Server (NTRS)

    Croft, Steven K.

    1993-01-01

    Tectonic features on Triton have been mapped as part of a larger study of the geology of Triton. Few purely tectonic structures are found on Triton: some grabens and possibly some compressive ridges. However, most of the other structures seen (primarily cryovolcanic in origin) exhibit tectonic control. A regional tectonic network has the following dominant orientations: N-S, E-W, NE-SW, and NW-SE. Most of the orientations are consistent with tidal deformations related to Triton's decreasing orbital radius. Localized quasi-concentric patterns may be due to interior processes such as mantle plumes.

  1. Sedimentation and preservation of the Miocene Atacama Gravels in the Pedernales Chañaral Area, Northern Chile: Climatic or tectonic control?

    NASA Astrophysics Data System (ADS)

    Nalpas, T.; Dabard, M.-P.; Ruffet, G.; Vernon, A.; Mpodozis, C.; Loi, A.; Hérail, G.

    2008-11-01

    In recent years, longitudinal changes on the thin/thick-skinned tectonic styles of the Central Andes has been intensively discussed while other studies have considered the role of mass transfers on the unloading of the orogen, and on the stress regime along the plate interface arising from changes on the volume of sediment arriving into the Peru-Chile trench. The search for paleo-climate records is therefore crucial for our understanding of the history of the Central Andes. In this paper, we focus on the Atacama Gravels, an extensive blanket of Miocene continental deposits filling a Neogene paleo-valley system along the southern Atacama Desert in northern Chile. An east-west transect, between Pedernales and Chañaral (26°30'S), enabled us to carry out a sedimentological and tectonic study of the Atacama Gravels, based on logging and field observations along the Rio Salado canyon. New 39Ar- 40Ar ages obtained on intercalated and overlying ignimbrites date the beginning of the Atacama Gravels sedimentation at around the Oligocene-Miocene boundary and cessation of sedimentation in the Late Miocene. Thirteen lithofacies, included within five facies associations (A1 to A5) were identified. Depositional environments vary from proximal alluvial fan (A1, A2) in the Precordillera through ephemeral fluvial (A3, A4) to distal playa lake (A5) in the Coastal Cordillera. No evidences of synsedimentary deformation have been found, showing that the change from sediment removal to sediment preservation cannot be explained by tectonic causes, and climate change appears to be the dominant controlling factor of sediment preservation. A progressive change from semi-arid towards hyper-arid climatic conditions during the Miocene, led to a reduction on the transport capacity of the fluvial system and sediment preservation along the paleo-valley system formed during the Oligocene.

  2. Compilation of historical information of 300 Area facilities and activities

    SciTech Connect

    Gerber, M.S.

    1992-12-01

    This document is a compilation of historical information of the 300 Area activities and facilities since the beginning. The 300 Area is shown as it looked in 1945, and also a more recent (1985) look at the 300 Area is provided.

  3. Geometrical modulation transfer function for different pixel active area shapes

    NASA Astrophysics Data System (ADS)

    Yadid-Pecht, Orly

    2000-04-01

    In this work we consider the effect of the pixel active area geometrical shape on the modulation transfer function (MTF) of an image sensor. When designing a CMOS Active Pixel Sensor, or a CCD or CID sensor for this matter, the active area of the pixel would have a certain geometrical shape which might not cover the whole pixel area. To improve the device performance, it is important to understand the effect this has on the pixel sensitivity and on the resulting MTF. We perform a theoretical analysis of the MTF for the active area shape and derive explicit formulas for the transfer function for pixel arrays with a square, a rectangular and an L shaped active area (most commonly used), and generalize for any connected active area shape. Preliminary experimental results of subpixel scanning sensitivity maps and the corresponding MTFs have also bee obtained, which confirm the theoretical derivations. Both the simulation results and the MTF calculated from the point spread function measurements of the actual pixel arrays show that the active area shape contributes significantly to the behavior of the overall MTF. The results also indicate that for any potential pixel active area shape, the effect of its diversion from the square pixel could be calculated, so that tradeoff between the conflicting requirements, such as SNR and MTF, could be compared per each pixel design for better overall sensor performance.

  4. Tectonics and metallogenic provinces

    USGS Publications Warehouse

    Guild, P.W.

    1983-01-01

    Various theories have been advanced to explain the well-known uneven distribution of metals and ore-deposit types in space and time. Primordial differences in the mantle, preferential concentration of elements in the crust, the prevalence of ore-forming processes at certain times and (or) places, and combinations of one or several of these factors have all been called upon to account for the "metallogenic provinces," which can be defined loosely as regions containing similar deposits of one or a group of metals or minerals. Because many, perhaps most, provinces have complex, multistage origins, the relative importance of inheritance vs. process is still controversial. In recent years the geographic relationship of many geologically young provinces to present-day plate-tectonic positions (accreting or consuming margins, intraplate structures, etc.) has been widely recognized, and the presumption is strong that older provinces had similar relationships to former plates. As most ore deposits resulted from a favorable conjunction of geological processes that are no longer operative, elucidation of their genesis requires reconstruction of the geologic history of the province, with particular emphasis on events coeval with mineralization. Tectonic analysis is an important aspect of this reconstruction; data from orbiting satellites have contributed greatly to this analysis, as the voluminous literature of the past decade testifies. Both the synoptic view of large areas and the ability to emphasize faint contrasts have revealed linear, curvilinear, and circular features not previously recognized from field studies. Some of these undoubtedly reflect basement structures that have contributed to the development, or limit the extent, of metallogenic provinces. Their recognition and delineation will be increasingly valuable to the assessment of resources available and as guides to exploration for the ores needed by future generations. ?? 1983.

  5. Applications of Quaternary stratigraphic, soil-geomorphic, and quantitative geomorphic analyses to the evaluation of tectonic activity and landscape evolution in the Upper Coastal Plain, South Carolina

    SciTech Connect

    Hanson, K.L.; Bullard, T.F.; de Wit, M.W.; Stieve, A.L.

    1993-07-01

    Geomorphic analyses combined with mapping of fluvial terraces and upland geomorphic surfaces provide new approaches and data for evaluating the Quaternary activity of post-Cretaceous faults that are recognized in subsurface data at the Savannah River Site in the Upper Coastal Plain of southwestern South Carolina. Analyses of longitudinal stream and terrace profiles, regional slope maps, and drainage basin morphometry indicate long-term uplift and southeast tilt of the site region. Preliminary results of drainage basin characterization suggests an apparent rejuvenation of drainages along the trace of the Pen Branch fault (a Tertiary reactivated reverse fault that initiated as a basin-margin normal fault along the northern boundary of the Triassic Dunbarton Basin). This apparent rejuvenation of drainages may be the result of nontectonic geomorphic processes or local tectonic uplift and tilting within a framework of regional uplift.

  6. Characterization of potential sources of magnetic anomalies within the crust in a tectonically active region: Amphibolites and migmatites from Potrillo Maar, New Mexico

    NASA Technical Reports Server (NTRS)

    Spear, F. S.; Padovanni, E.

    1985-01-01

    The purpose was to characterize the oxide mineralogy and petrology of samples collected from Potrillo Maar, New Mexico with the goal of explaining the magnetic anamoly that is observed over this region from remote sensing. Potrillo Maar is a diatreme that has brought rocks from all depths in the crust to the surface almost instantaneously. The samples are therefore thought to be representative of the crust as it exists today below this portion of the Rio Grande Rift. It is generally believed that oxide minerals (magnetite, hematite, etc.) are responsible for the magnetic signature of the crust. The samples from Portillo Maar therefore offer a unique opportunity to examine the magnetic mineralogy of the entire crust. The results indicate that the magnetic anamoly observed over Rio Grande Rift may be consequence of the tectonic activity that caused mylonitization of the rocks and allowed the infiltration of oxidizing fluids.

  7. Global Tectonics of Enceladus: Numerical Model

    NASA Astrophysics Data System (ADS)

    Czechowski, Leszek

    2016-10-01

    Introduction: Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where volcanic and tectonic activities are observed. Every second, the mass of 200 kg is ejected into space from the South Polar Terrain (SPT) – [1]. The loss of matter from the body's interior should lead to global compression of the crust. Typical effects of compression are: thrust faults, folding and subduction. However, such forms are not dominant on Enceladus. We propose here special tectonic process that could explain this par