44 research outputs found

    Comparison between Venetian and Western Carpathian Late Eocene bryozoan faunas.

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    From a critical examination of the previous papers about the Upper Eocene bryozoan faunas of NE Italy (Venetia region) and Western Carpathian Mountains (Slovakia and Hungary) it appears that there are 148 valid species (97 Cheilostomata and 50 Cyclostomata). The remarkable lithological and faunistocal affinities of the two sedimentary basins are compared and emphasized, especially with regard to the bryozoan associations. The paleogeography and relationships of these Tethyan areas are briefly examined

    Archaeoseismology of the AD 1545 earthquake in Chiang Mai, Northern Thailand

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    The A.D. 1545 Chiang Mai earthquake in northern Thailand was studied by historical and archaeological sources.The temple Wat Chedi Luang has lost about half of the original 80-metres height due to southward-directed collapse. Twenty-one temple sites – out of 74 visited – has tilted pagodas, up to 5° in various directions, dominated by a SE trend. All damaged temples were built before the 1545 earthquake. We suggest that a city-wide liquefaction event caused tilting. The responsible earthquake possibly occurred along the Doi Suthep Fault within city limits. Possible activity of distant faults is assessed

    Late Holocene shorelines deduced from tidal notches on both sides of the Ionian Thrust (Greece): Fiscardo Peninsula (Cephalonia) and Ithaca Island.

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    Fossil shorelines produced by recent co-seismic movements were identified throughasubmarine survey along the coasts of Ithaca and Fiscardo (Greece).In both areas a tidal notch-slightly submerged below present Mean Sea Level (MSL) was observed at various sites. This “modern” notch is known to have been submerged by the global sea-level rise during the 19th and 20th centuries. The depth after tide and air-pressure correction of the vertex of the “modern” notch (that owes its submergence to the current rapid sea level rise) was measured between -20 and -30±5cm at Fiscardo and between -36 and -45±6cm at Ithaca. This “modern” notch at the same depth on east and west sides of the Ionian Thrust suggests that both areas were not affected by the co-seismic vertical movements that occurred in 1953 (in the wider area). On the other hand, a greater depth in Ithaca could be an effect of co-seismic subsidence. Over the long term, the tectonic behavior of Ithaca differs from Fiscardo. At Ithaca no evidence of emergence was found and Holocene vertical movements have been only of subsidence: submerged fossil tidal notches were distinguished below MSL at about -40 (modern), -60, -75, -95, -106, -126, -150 and -220±6cm. On the East coast of Fiscardo peninsula impacts of ancient earthquakes have left some marks of emergence at about +18 and +44±5cm, and of submergence at about -25 (modern), -45, -60, -75, -82, -100 and -230cm, with even some evidence of past uplift and subsidence at the same sites

    Miocene siliciclastic deposits of Naxos Island: Geodynamic and environmental implications for the evolution of the southern Aegean Sea (Greece)

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    An interdisciplinary study has been carried out on Naxos Island, located in the southern Aegean Sea (Greece), which shows Miocene geodynamic and environmental changes in a classic example of a collapsing orogen. Early to Mid-Miocene siliciclastic deposits on Naxos have been shed from an uplifting mountainous realm in the south, which included a patchwork of at least four source terrains of different thermal histories.Petrography of pebbles suggests that the source units formed part of a passivecontinental margin succession (external Pelagonian unit), and an ophiolite succession mainly of deep-water cherts and limestones deposited on basalt substratum (Pindos unit). The continental margin source contributed rounded zircon crystals of Late Jurassic to Early Cretaceous age and broadly scattering Paleozoic zircon fission-track cooling ages. A distal pebble assemblage of Paleogene shallow-water carbonates passing into flysch-like, mixed calcarenitic and siliciclastic components with volcanic arc components is subordinately present. High-grade metamorphic components from the nearby metamorphic core complex are not present. The depositional evolution reflects increasing relief and, in some parts, a fluvial succession with rhythmic channel deposition, possibly due to runoff variability forced by orbital cyclicity. Upsection, the depositional trend indicates increasing seasonality and decreasing humidity in the source region. The Miocene sedimentary succession has been deposited on an ophiolite nappe. Juxtaposition of this ophiolite nappe occurred as an extensional allochthon during large-scale extension in the Aegean region at the margins of an exhuming metamorphic core complex

    Rapid Profiling of Marine Notches Using a Handheld Laser Distance Meter

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    A rapid, single-user profiling method for rocky shores is described. The Leica Disto D8 handheld laser distance meter measures distance up to 100 m and inclination in 360 degrees. It automatically calculates horizontal distance and vertical elevation. Memory storage accommodates data for 30 measurement points, allowing easy plotting of shore profiles. This technique allows even inaccessible, dangerous, and overhanging cliff faces to be evaluated faithfully and within minutes. It is a major improvement over standard methods that often involve risky coasteering and climbing. Examples are given from marine notches in Thailand

    GEOMETRY OF HOLOCENE TIDAL NOTCHES – SEA LEVEL MARKERS AT PERACHORA PENINSULA, GULF OF CORINTH, GREECE

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    Tidal notches are a generally accepted sea level indicator that, when different from mean sea level, witness tectonic activity at or near coastlines. However, how to infer related information is controversial since tectonic uplift from a single seismic event is not likely to exceed several decimetres. High resolution laser scanning offers the availability of close-up views on exposures and to detect evidence for multiple sea level indicators in between major emergence. Statistically representative profiles along exposure were analysed in order to prove for already described tidal notches and to highlight similar shapes in consistent geometries along coastal cliffs of Perachora Peninsula.</jats:p
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