196,035 research outputs found
Regional deformation and offshore crustal local faulting as combined processes to explain uplift through time constrained by investigating differentially-uplifted Late Quaternary palaeoshorelines: the foreland Hyblean Plateau, SE Sicily.
No full textQuaternary uplift is well documented in SE Sicily, a region prone to damaging seismic events, such as the 1693 “Val di Noto” Earthquake (Mw 7.4), the largest seismic event reported within the Italian Earthquake Catalogue, whose seismogenic source is still debated and, consequently, the long-term seismic hazard is poorly-understood. However, the spatial variation in the timing and rates of uplift are still debated, so it is difficult to link the dominant tectonic process(es) responsible for the uplift and the location of seismogenic sources. To better constrain the uplift rate, we have refined the dating of Late Quaternary marine terraces, using a synchronous correlation approach, driven by both published and newly obtained numerical age controls (234U/230Th dating on corals). This has allowed re-calculation of uplift rates along a N-S oriented transect within the Hyblean Plateau (HP) foreland region. Consequently, we have mapped the geometry of palaeoshorelines along a coastline-parallel transect, and hence the rates of uplift. The results suggest increasing uplift rate from south to north across the HP, and that uplift rates have remained constant through the late Quaternary. This spatially-changing but temporally constant uplift places constraints on the proportion of uplift produced by regional geodynamic processes versus produced by local faults, such as an offshore E-dipping active normal fault. We discuss these new findings in terms of the long-term seismic hazard for one of the most seismically-active regions in the Mediterranean Basin
The Relationships Between Regional Quaternary Uplift, Deformation Across Active Normal Faults, and Historical Seismicity in the Upper Plate of Subduction Zones: The Capo D'Orlando Fault, NE Sicily
No full textIn order to investigate the deformation within the upper plate of the Calabrian subduction zone, we have mapped and modeled a sequence of Late Quaternary paleoshorelines tectonically deformed by the Capo D'Orlando normal fault, NE Sicily, which forms part of the actively deforming Calabrian Arc. In addition to the 1908 Messina Strait earthquake (Mw 7.1), this region has experienced damaging earthquakes, possibly on the Capo D'Orlando Fault; however, it is not considered by some to be a potential seismogenic source. Uplifted Quaternary paleoshorelines are preserved on the hangingwall of the Capo D'Orlando Fault, indicating that hangingwall subsidence is counteracted by regional uplift, likely because of deformation associated with subduction/collision. We attempt to constrain the relationship between regional uplift, crustal extensional processes, and historical seismicity, and we quantify both the normal and regional deformation signals. We report uplift variations along the strike of the fault and use a synchronous correlation technique to assign ages to paleoshorelines, facilitating calculation of uplift rates and the fault throw rate. Uplift rates in the hangingwall increase from 0.4 mm/year in the center of the fault to 0.89 mm/year beyond its SW fault tip, suggesting 0.5 mm/year of fault-related subsidence, which implies a throw rate of 0.63 ± 0.02 mm/year, and significant seismic hazard. Overall, we emphasize that upper plate extension and related vertical motions complicate the process of deriving information on the subduction/collision process, such as coupling and slip distribution on the subduction interface, parameters that are commonly inferred for other subduction zones without considering upper plate deformation
The implications of revised Quaternary palaeoshoreline chronologies for the rates of active extension and uplift in the upper plate of subduction zones
No full textWe demonstrate a synchronous correlation technique to determine the chronology of Quaternary palaeoshorelines to test proposed relationships between tectonics, climate and sea-level change. The elevations of marine palaeoshorelines in Calabria around the active Vibo normal fault have been measured from TIN DEM 10m data and fieldwork and correlated with global sea-level curves. A synchronous correlation method and new U/Th dates are used to ascertain how the slip-rate on the fault relates to uplift rates across the region. Regional uplift, possibly associated with subduction along the Calabrian trench or due to the cumulative effect of closely-spaced active normal faults, is rapid enough to uplift even the hangingwall of the Vibo normal fault; the actual value for the rate of background uplift can only be ascertained once the rate of slip on the Vibo fault is subtracted. Synchronous correlation of multiple palaeoshorelines sampled along 29 elevation profiles with global sea-levels shows that the resultant uplift rate (background uplift minus local hangingwall subsidence) is constant through time from 0 to 340ka, and not fluctuating by a factor of 4 as previously suggested. The uplift rate increases from 0.4mm/yr at the centre of the hangingwall of the fault to 1.75mm/yr in the hangingwall in the vicinity of the fault tip. Palaeoshorelines can be traced from the hangingwall to the footwall around the fault tip and hence correlated across the fault. The throw-rate on the fault averaged over 340ka decreases from a maximum at the centre of the fault (1mm/yr) to zero at the tip. This gradient in throw-rate explains the spatial variation in resultant uplift rates along the fault. We interpret the 1.75mm/yr resultant uplift rate at and beyond the fault tip as the signature of a regional uplift, presumably related to subduction, although we cannot exclude the possibility that other local faults influence this uplift; the lower uplift rates in the hangingwall of the fault are due to interaction between "regional" uplift and subsidence associated with the local active normal faulting. We discuss (a) how our synchronous correlation technique should trigger a re-appraisal of palaeoshoreline chronologies worldwide, and (b) the implications for the tectonics and seismic hazard of Calabria, suggesting that perturbations in the uplift-rate field are a key criterion to map the locations of active faults, their deformation rates, and hence seismic hazard above subduction zones. © 2013 Elsevier Ltd
Distributed normal faulting in the tip zone of the South Alkyonides Fault System, Gulf of Corinth, constrained using 36Cl exposure dating of late-Quaternary wave-cut platforms
No full textThe geometry, rates and kinematics of active faulting in the region close to the tip of a major crustal-scale normal fault in the Gulf of Corinth, Greece, are investigated using detailed fault mapping and new absolute dating. Fault offsets have been dated using a combination of 234U/230Th coral dates and in situ 36Cl cosmogenic exposure ages for sediments and wave-cut platforms deformed by the faults. Our results show that deformation in the tip zone is distributed across as many as eight faults arranged within ~700 m across strike, each of which deforms deposits and landforms associated with the 125 ka marine terrace of Marine Isotope Stage 5e. Summed throw-rates across strike achieve values as high as 0.3–1.6 mm/yr, values that are comparable to those at the centre of the crustal-scale fault (2–3 mm/yr from Holocene palaeoseismology and 3–4 mm/yr from GPS geodesy). The relatively high deformation rate and distributed deformation in the tip zone are discussed in terms of stress enhancement from rupture of neighbouring crustal-scale faults and in terms of how this should be considered during fault-based seismic hazard assessment
Refining the middle-late Pleistocene chronology of marine terraces and uplift history in a sector of the Apulian foreland (southern Italy) by applying a synchronous correlation technique and amino acid racemization to Patella spp. And Thetystrombus latus
No full textFor the first time, the synchronous correlation technique and amino acid racemization (AAR) analyses of Patella spp. and Thetystrombus latus shells are applied to an understudied sequence of raised palaeoshorelines to refine the knowledge about terrace phases and uplift history in the middle-late Pleistocene in a sector of the Apulian foreland (western coast of the Salento Peninsula, southern Italy). These combined methodologies provide the first chronological attribution for middle-late Pleistocene palaeoshorelines and quantitative assessment of vertical crustal movements in this sector of the Apulian foreland, which, to date, has been characterised by a scarcity of reliable chronological data. By applying a synchronous correlation technique driven by new AAR analyses, we iterate different uplift rate scenarios to find the best match between digital terrain model and field-based observed palaeoshorelines and "expected" sea level highstand elevations. Our results show that two uplift rate scenarios could explain the mapped geomorphology: (i) scenario 1 suggests fluctuating uplift rates over time with an uplift rate of 0.15 mm/y until 130 ky BP (middle Pleistocene, interval MIS 15 - MIS 6; that is, 590 - 130 ky BP) and of 0.07 mm/y from 130 ky BP to the present; on the other hand, (ii) scenario 2 suggests a constant uplift rate of 0.12 mm/y over time in the middle-late Pleistocene. The palaeoshorelines recognised in this study are related to the following highstands: 119 ky BP (MIS 5.5 second peak), 125 ky BP (MIS 5.5), 240 ky BP (MIS 7.5), 340 ky BP (MIS 9.3), and 478 ky BP (MIS 13.1) for both scenarios 1 and 2. The two scenarios only differ in the oldest palaeoshoreline: 560 ky BP (MIS 15.3) in scenario 1 and 550 ky BP (MIS 15.1) in scenario 2. Our results highlight how the number of preserved palaeoshorelines is controlled by uplift rates; indeed, in this area, we show that fewer palaeoshorelines are preserved than in regions where higher uplift rates have been inferred, suggesting a more prominent effect of the "overprinting" or re-occupation of younger sea level highstands over the older sea level highstands. Finally, we discuss geomorphological and geological implications of using a synchronous correlation approach, driven by new age controls, to model raised palaeoshorelines where relatively low uplift rates have been mapped within well-known geodynamically stable regions, such as the Apulian foreland, southern Italy
Distributed normal faulting in the tip zone of the South Alkyonides Fault System, Gulf of Corinth, constrained using 36Cl exposure dating of late-Quaternary wave-cut platforms
No full textThe geometry, rates and kinematics of active faulting in the region close to the tip of a major crustal-scale normal fault in the Gulf of Corinth, Greece, are investigated using detailed fault mapping and new absolute dating. Fault offsets have been dated using a combination of 234U/230Th coral dates and in situ 36Cl cosmogenic exposure ages for sediments and wave-cut platforms deformed by the faults. Our results show that deformation in the tip zone is distributed across as many as eight faults arranged within ~700 m across strike, each of which deforms deposits and landforms associated with the 125 ka marine terrace of Marine Isotope Stage 5e. Summed throw-rates across strike achieve values as high as 0.3–1.6 mm/yr, values that are comparable to those at the centre of the crustal-scale fault (2–3 mm/yr from Holocene palaeoseismology and 3–4 mm/yr from GPS geodesy). The relatively high deformation rate and distributed deformation in the tip zone are discussed in terms of stress enhancement from rupture of neighbouring crustal-scale faults and in terms of how this should be considered during fault-based seismic hazard assessment
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
- …
