نتایج جستجو برای: uplift and magmatism
تعداد نتایج: 16828102 فیلتر نتایج به سال:
[1] Vertical crustal motions at 15 sites along the northern Pacific-North America plate boundary are determined using relative sea level changes from tide gauge records. Our analysis is based on monthly mean sea levels, from which barometric pressure and seasonal effects are removed. The records are corrected for common-mode oceanographic variations. These records are statistically examined for...
Abstract A sill covering an area of more than 15 km 2 , several dykes up to 5 m thick and a volcanoclastic deposit crop out with similar petrology in the sector Atienza (NW Iberian Chain, Spain). They consist calc-alkaline porphyritic andesites phenocrysts plagioclase, amphibole, biotite, garnet orthopyroxene. Based on U–Pb zircon analysis, age 290 ± 3 Ma (Sakmarian-Artinskian Cisuralian) has b...
Relief wells are used extensively to relieve excess hydrostatic pressure in pervious foundation strata overlain by impervious top strata, conditions which often exist landward of levees and downstream of dams and hydraulic structures. Placing well outlets in below-surface trenches or collector pipes helps dry up seepage areas downstream of levees and dams. Relief wells are often used in combina...
Our observations show that extreme uplift in southeast Alaska began about 1770 AD, with relative sea level (RSL) change to 5.7 m and current uplift rates to 32 mm/yr. This region experienced widespread glacial melting following the Little Ice Age (LIA), with the collapse of the Glacier Bay Icefield alone equivalent to 8 mm of global sea level rise. Geodynamic modelling links the uplift to post-...
Fission track analysis of apatites from basement rocks of the Wright Valley in southern Victoria Land provides information about the timing. the amount and hence the rate of uplift of the Transantarctic Mountains in this area. Apatite ages increase systematically with elevation, and a pronounced break in the age versus elevation profile has been recognised at about 800 m on Mt. Doody near the m...
[1] Seasonal melting of the coastal part of the Greenland ice sheet is investigated using GPS vertical displacement data from coastal stations, combined with data on atmospheric and ocean temperatures. Using a high pass filter and cubic spline models, we estimate five variables describing seasonal uplift, a proxy for proximal mass loss, including duration of the melt season and the amount of su...
Anchors are widely used in foundation systems for structures requiring uplift resistance. As demonstrated by numerous theoretical and experimental studies on the subject, uncertainty remains as to both the theoretical uplift capacity of anchors in idealised soils and the suitability of the various modelling assumptions in capturing the responses observed during tests. This study, which deals ex...
[1] Coastal stratigraphy of eastern Hokkaido indicates that decimeters of coastal uplift occurred repeatedly in the late Holocene. Employing radiocarbon dating and tephrochronology, we identify along a 100 km length of the Kuril subduction zone six uplift events since 2,800 years B.P. Uplift events occur at the same frequency as unusually high tsunamis. Each coastal uplift event, which occurs o...
Estimating pore pressure in the Cooper Basin, South Australia: sonic log method in an uplifted basin
The use of sonic log data to analyse overpressure in the Cooper Basin, South Australia is complicated by the occurrence of Tertiary uplift in the basin. Uplift and overpressure are both associated with anomalous porosity/depth relationships: the former being witnessed by overcompaction and the later by undercompaction. Hence uplift may mask overpressure effects on log data. A normal compaction ...
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