980 resultados para MGS3 stratigraphic segment
Resumo:
The Thrace Basin is the largest and thickest Tertiary sedimentary basin of the eastern Balkans region and constitutes an important hydrocarbon province. It is located between the Rhodope-Strandja Massif to the north and west, the Marmara Sea and Biga Peninsula to the south, and the Black Sea to the est. It consists of a complex system of depocenters and uplifts with very articulate paleotopography indicated by abrupt lateral facies variations. Its southeastern margin is widely deformed by the Ganos Fault, a segment of the North Anatolian strike-slip fault system . Most of the Thrace Basin fill ranges from the Eocene to the Late Oligocene. Maximum total thickness, including the Neogene-Quaternary succession, reaches 9.000 meters in a few narrow depocenters. This sedimentary succession consists mainly of basin plain turbiditic deposits with a significant volcaniclastic component which evolves upwards to shelf deposits and continental facies, with deltaic bodies prograding towards the basin center in the Oligocene. This work deals with the provenance of Eocene-Oligocene clastic sediments of the southern and western part of Thrace Basin in Turkey and Greece. Sandstone compositional data (78 gross composition analyses and 40 heavy minerals analyses) were used to understand the change in detrital modes which reflects the provenance and geodinamic evolution of the basin. Samples were collected at six localities, which are from west to est: Gökçeada, Gallipoli and South-Ganos (south of Ganos Fault), Alexandroupolis, Korudağ and North-Ganos (north of Ganos Fault). Petrologic (framework composition and heavy-mineral analyses) and stratigraphic-sedimentologic data, (analysis of sedimentologic facies associations along representative stratigraphic sections, paleocurrents) allowed discrimination of six petrofacies; for each petrofacies the sediment dispersal system was delineated. The Thrace Basin fill is made mainly of lithic arkoses and arkosic litharenites with variable amount of low-grade metamorphic lithics (also ophiolitic), neovolcanic lithics, and carbonate grains (mainly extrabasinal). Picotite is the most widespread heavy mineral in all petrofacies. Petrological data on analyzed successions show a complex sediment dispersal pattern and evolution of the basin, indicating one principal detrital input from a source area located to the south, along both the İzmir-Ankara and Intra-Pontide suture lines, and a possible secondary source area, represented by the Rhodope Massif to the west. A significant portion of the Thrace Basin sediments in the study area were derived from ophiolitic source rocks and from their oceanic cover, whereas epimetamorphic detrital components came from a low-grade crystalline basement. An important penecontemporaneous volcanic component is widespread in late Eocene-Oligocene times, indicating widespread post-collisional (collapse?) volcanism following the closure of the Vardar ocean. Large-scale sediment mass wasting from south to north along the southern margin of the Thrace Basin is indicated (i) in late Eocene time by large olistoliths of ophiolites and penecontemporaneous carbonates, and (ii) in the mid-Oligocene by large volcaniclastic olistoliths. The late Oligocene paleogeographic scenario was characterized by large deltaic bodies prograding northward (Osmancik Formation). This clearly indicates that the southern margin of the basin acted as a major sediment source area throughout its Eocene-Oligocene history. Another major sediment source area is represented by the Rhodope Massif, in particolar the Circum-Rhodopic belt, especially for plutonic and metamorphic rocks. Considering preexisting data on the petrologic composition of Thrace Basin, silicilastic sediments in Greece and Bulgaria (Caracciolo, 2009), a Rhodopian provenance could be considered mostly for areas of the Thrace Basin outside our study area, particularly in the northern-central portions of the basin. In summary, the most important source area for the sediment of Thrace Basin in the study area was represented by the exhumed subduction-accretion complex along the southern margin of the basin (Biga Peninsula and western-central Marmara Sea region). Most measured paleocurrent indicators show an eastward paleoflow but this is most likely the result of gravity flow deflection. This is possible considered a strong control due to the east-west-trending synsedimentary transcurrent faults which cuts the Thrace Basin, generating a series of depocenters and uplifts which deeply influenced sediment dispersal and the areal distribution of paleoenvironments. The Thrace Basin was long interpreted as a forearc basin between a magmatic arc to the north and a subduction-accretion complex to the south, developed in a context of northward subduction. This interpretation was challenged by more recent data emphasizing the lack of a coeval magmatic arc in the north and the interpretation of the chaotic deposit which outcrop south of Ganos Fault as olistoliths and large submarine slumps, derived from the erosion and sedimentary reworking of an older mélange unit located to the south (not as tectonic mélange formed in an accretionary prism). The present study corroborates instead the hypothesis of a post-collisional origin of the Thrace Basin, due to a phase of orogenic collapse, which generated a series of mid-Eocene depocenters all along the İzmir-Ankara suture (following closure of the Vardar-İzmir-Ankara ocean and the ensuing collision); then the slab roll-back of the remnant Pindos ocean played an important role in enhancing subsidence and creating additional accommodation space for sediment deposition.
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The modern stratigraphy of clastic continental margins is the result of the interaction between several geological processes acting on different time scales, among which sea level oscillations, sediment supply fluctuations and local tectonics are the main mechanisms. During the past three years my PhD was focused on understanding the impact of each of these process in the deposition of the central and northern Adriatic sedimentary successions, with the aim of reconstructing and quantifying the Late Quaternary eustatic fluctuations. In the last few decades, several Authors tried to quantify past eustatic fluctuations through the analysis of direct sea level indicators, among which drowned barrier-island deposits or coral reefs, or indirect methods, such as Oxygen isotope ratios (δ18O) or modeling simulations. Sea level curves, obtained from direct sea level indicators, record a composite signal, formed by the contribution of the global eustatic change and regional factors, as tectonic processes or glacial-isostatic rebound effects: the eustatic signal has to be obtained by removing the contribution of these other mechanisms. To obtain the most realistic sea level reconstructions it is important to quantify the tectonic regime of the central Adriatic margin. This result has been achieved integrating a numerical approach with the analysis of high-resolution seismic profiles. In detail, the subsidence trend obtained from the geohistory analysis and the backstripping of the borehole PRAD1.2 (the borehole PRAD1.2 is a 71 m continuous borehole drilled in -185 m of water depth, south of the Mid Adriatic Deep - MAD - during the European Project PROMESS 1, Profile Across Mediterranean Sedimentary Systems, Part 1), has been confirmed by the analysis of lowstand paleoshorelines and by benthic foraminifera associations investigated through the borehole. This work showed an evolution from inner-shelf environment, during Marine Isotopic Stage (MIS) 10, to upper-slope conditions, during MIS 2. Once the tectonic regime of the central Adriatic margin has been constrained, it is possible to investigate the impact of sea level and sediment supply fluctuations on the deposition of the Late Pleistocene-Holocene transgressive deposits. The Adriatic transgressive record (TST - Transgressive Systems Tract) is formed by three correlative sedimentary bodies, deposited in less then 14 kyr since the Last Glacial Maximum (LGM); in particular: along the central Adriatic shelf and in the adjacent slope basin the TST is formed by marine units, while along the northern Adriatic shelf the TST is represented by costal deposits in a backstepping configuration. The central Adriatic margin, characterized by a thick transgressive sedimentary succession, is the ideal site to investigate the impact of late Pleistocene climatic and eustatic fluctuations, among which Meltwater Pulses 1A and 1B and the Younger Dryas cold event. The central Adriatic TST is formed by a tripartite deposit bounded by two regional unconformities. In particular, the middle TST unit includes two prograding wedges, deposited in the interval between the two Meltwater Pulse events, as highlighted by several 14C age estimates, and likely recorded the Younger Dryas cold interval. Modeling simulations, obtained with the two coupled models HydroTrend 3.0 and 2D-Sedflux 1.0C (developed by the Community Surface Dynamics Modeling System - CSDMS), integrated by the analysis of high resolution seismic profiles and core samples, indicate that: 1 - the prograding middle TST unit, deposited during the Younger Dryas, was formed as a consequence of an increase in sediment flux, likely connected to a decline in vegetation cover in the catchment area due to the establishment of sub glacial arid conditions; 2 - the two-stage prograding geometry was the consequence of a sea level still-stand (or possibly a fall) during the Younger Dryas event. The northern Adriatic margin, characterized by a broad and gentle shelf (350 km wide with a low angle plunge of 0.02° to the SE), is the ideal site to quantify the timing of each steps of the post LGM sea level rise. The modern shelf is characterized by sandy deposits of barrier-island systems in a backstepping configuration, showing younger ages at progressively shallower depths, which recorded the step-wise nature of the last sea level rise. The age-depth model, obtained by dated samples of basal peat layers, is in good agreement with previous published sea level curves, and highlights the post-glacial eustatic trend. The interval corresponding to the Younger Dyas cold reversal, instead, is more complex: two coeval coastal deposits characterize the northern Adriatic shelf at very different water depths. Several explanations and different models can be attempted to explain this conundrum, but the problem remains still unsolved.
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Background: Chronic kidney disease (CKD) is one of the strongest risk factor for myocardial infarction (MI) and mortality. The aim of this study was to assess the association between renal dysfunction severity, short-term outcomes and the use of in-hospital evidence-based therapies among patients with non–ST-segment elevation myocardial infarction (NSTEMI). Methods: We examined data on 320 patients presenting with NSTEMI to Maggiore’s Emergency Department from 1st Jan 2010 to 31st December 2011. The study patients were classified into two groups according to their baseline glomerular filtration rate (GFR): renal dysfunction (RD) (GFR<60) and non-RD (GFR≥60 ml/min). Patients were then classified into four groups according to their CKD stage (GFR≥60, GFR 59-30, GFR 29-15, GFR <15). Results: Of the 320 patients, 155 (48,4%) had a GFR<60 ml/min at baseline. Compared with patients with a GFR≥60 ml/min, this group was, more likely to be female, to have hypertension, a previous myocardial infarction, stroke or TIA, had higher levels of uric acid and C-reactive protein. They were less likely to receive immediate (first 24 hours) evidence-based therapies. The GFR of RD patients treated appropriately increases on average by 5.5 ml/min/1.73 m2. The length of stay (mean, SD) increased with increasing CKD stage, respectively 5,3 (4,1), 7.0 (6.1), 7.8 (7.0), 9.2 (5.8) (global p <.0001). Females had on average a longer hospitalization than males, regardless of RD. In hospital mortality was higher in RD group (3,25%). Conclusions: The in-hospital mortality not was statically difference among the patients with a GFR value ≥60 ml/min, and patients with a GFR value <60 ml/min. The length of stay increased with increasing CKD stages. Despite patients with RD have more comorbidities then without RD less frequently receive guideline –recommended therapy. The GFR of RD patients treated appropriately improves during hospitalization, but not a level as we expected.
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The association of several favorable factors has resulted in the development of a wide barchan dune field that stands out as a fundamental element in the coastal landscape of southern Santa Catarina state in Brazil. This original ecosystem is being destroyed and highly modified, due to urbanization. This work identifies and discusses its basic characteristics and analyzes the favorable factors for its preservation, in the foreseen of both a sustainable future and potential incomes from ecotourism. The knowledge of the geologic evolution allows to associate this transgressive Holocene dunes formation to more dissipative beach conditions. Spatial differences on morphodynamics are related to local and regional contrasts in the sediment budget, with an influence on gradients of wave attenuation in the inner shelf and consequently with influence in the level of coastal erosion. The link between relative sea level changes and coastal eolian sedimentation can be used to integrate coastal eolian systems to the sequence stratigraphy model. The main accumulation phase of eolian sediments would occur during the final transgressive and highstand systems tracts. Considering the global character of Quaternary relative sea level changes, the Laguna transgressive dune field should be correlated with similar eolian deposits developed along other parts of the Brazilian coast compatibles with the model of dunefield initiation during rising and highstand sea level phases.
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To evaluate the intraoperative use of handheld Fourier-domain optical coherence tomography (OCT) during Descemet stripping automated endothelial keratoplasty (DSAEK) to assess the donor-host interface.
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This study sought to assess outcomes in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention (PCI) for unprotected left main (LM) disease.
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To evaluate safety and effectiveness of early generation drug-eluting stents (DES) compared with bare-metal stents (BMS) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI), and to determine whether benefits and risks vary over time.
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The aim of this paper was to evaluate the efficacy of a novel 4-F compatible self-expanding Nitinol stent for the treatment of long femoro-popliteal obstructions.
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The prognostic relevance of quantitative an intracoronary occlusive electrocardiographic (ECG) ST-segment shift and its determinants have not been investigated in humans. In 765 patients with chronic stable coronary artery disease, the following simultaneous quantitative measurements were obtained during a 1-minute coronary balloon occlusion: intracoronary ECG ST-segment shift (recorded by angioplasty guidewire), mean aortic pressure, mean distal coronary pressure, and mean central venous pressure (CVP). Collateral flow index (CFI) was calculated as follows: (mean distal coronary pressure minus CVP)/(mean aortic pressure minus CVP). During an average follow-up duration of 50 ± 34 months, the cumulative mortality rate from all causes was significantly lower in the group with an ST-segment shift <0.1 mV (n = 89) than in the group with an ST-segment shift ≥0.1 mV (n = 676, p = 0.0211). Factors independently related to intracoronary occlusive ECG ST-segment shift <0.1 mV (r(2) = 0.189, p <0.0001) were high CFI (p <0.0001), intracoronary occlusive RR interval (p = 0.0467), right coronary artery as the ischemic region (p <0.0001), and absence of arterial hypertension (p = 0.0132). "High" CFI according to receiver operating characteristics analysis was ≥0.217 (area under receiver operating characteristics curve 0.647, p <0.0001). In conclusion, absence of ECG ST-segment shift during brief coronary occlusion in patients with chronic coronary artery disease conveys a decreased mortality and is directly influenced by a well-developed collateral supply to the right versus left coronary ischemic region and by the absence of systemic hypertension in a patient's history.
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PURPOSE: Limited information is available concerning changes in the urodynamic characteristics of orthotopic bladder substitutes with time. Therefore, we compared early and late urodynamic results in patients with an ileal orthotopic bladder substitute combined with an afferent tubular segment. MATERIALS AND METHODS: Of 139 patients surviving at least 5 years after cystoprostatectomy and ileal orthotopic bladder substitution with an afferent tubular segment 119 underwent urodynamic assessment, including 66 at a median of 9 months (early) and 77 at a median of 62 months (late). Of these patients 24 were assessed at each time point. Simultaneously all patients were asked to complete a bladder diary and questionnaire regarding continence for at least 3 days in the week preceding the urodynamic study. RESULTS: Urodynamic parameters were comparable in patients who were evaluated early and late postoperatively. In addition, median values at early and late urodynamic evaluation in the 24 patients with the 2 examinations showed no statistically significant differences for volume at first desire to void (300 vs 333 ml, p = 0.85), pressure at first desire to void (12 vs 13 cm H2O, p = 0.57), maximum cystometric capacity (450 vs 453 ml, p = 0.84), end filling pressure (19 vs 20 cm H2O, p = 0.17), reservoir compliance (25 vs 28 ml/cm H2O, p = 0.58) or post-void residual urine volume (5 vs 15 ml, p = 0.27). CONCLUSIONS: Urodynamic results after 5 years of living with an ileal orthotopic bladder substitute with an afferent tubular segment show grossly unchanged urodynamic characteristics. Patients maintain a reservoir capacity and micturition pattern consistent with a normal life-style. Reservoir pressure remained low, thereby protecting and preserving upper tract function. To achieve these results patients must be regularly followed, and the causes of bacteriuria, increased post-void residual urine and bladder outlet obstruction must be recognized and dealt with accordingly.