104,067 research outputs found
Daniel G. Prosser Civil War diary
No full textThis collection contains a pocket diary kept from 1862 to 1864 by Daniel G. Prosser of the 1st Indiana Cavalry
An exposed cross-section of Late Hercynian upper and intermediate continental crust in the Sila nappe (Calabria, S. Italy)
No full textThe complete Apennines orogenic cycle preserved in a transient single outcrop near San Fele, Lucania, Southern Italy
No full textOrogenic cycles may be viewed as comprising two extensional stages that are separated by a stage of contraction. This sequence has characterized the evolution of most mountain belts resulting from continental collision, and the structural signature of individual stages is recognized on a wide variety of scales, i.e. from microscopic to regional. Whereas the history of mountain belts is generally inferred from observations carried out at different sites, the entire sequence of deformation is very rarely recorded in single exposures. The double switch in tectonic regime that led to the development of the Lucanian Apennines in southern Italy, from pre-orogenic drifting through synorogenic thrusting to post-orogenic extension, is preserved in a superb metre-scale outcrop at Serra Manarella, in the vicinity of San Fele. A Late Jurassic, synsedimentary normal fault is sealed by strata affected by a Mid-Pliocene thrust-related fold. This composite structure, in turn, is truncated by a Mid-Pleistocene normal fault. Observation of these relationships represents a unique opportunity to unequivocally establish the relative chronology of deformations in the Lucanian Apennines, and may provide useful constraints for regional cross-section restoration
The abundance of 55 elements and petrovolumetric models of the crust in the Sila nappe, Calabria (site 7). In SASSI F.P. The abundance of 55 elements and petrovolumetric models of the crust in 9 type areas from the crystalline basements of Italy, with some Geophysical and petrophysical data
No full textHow We Voted
No full textAF beat Cherberg in Prosser, WA, and beat the other Republicans but not Cherberg in Benton County
Thermal history vs. fabric anisotropy in granitoids emplaced at different crustal levels: an example from Calabria, southern Italy
No full textThe Sila and Serre granitoids of Calabria were emplaced in the late
Carboniferous at depths ranging from 6 to 23 km in a postcollisional
extensional regime. Their fabric, which developed during and after final
crystallization up to the solid state, strongly increases in intensity
with emplacement depth, This relationship is attributed to the thermal
history of the Calabrian basement. Cooling histories of granitoids,
constrained by geological data and Rb-Sr cooling ages on micas,
demonstrate that residence times of rocks at temperatures greater than
those of the brittleductile transition vary greatly as a function of
initial emplacement depth. This explains why shallow-level granitoids,
that remained for about 10 Myr at temperatures above those of the
brittle domain, retain their original magmatic fabric, By contrast, the
strong fabrics of the deep-seated granitoids are explained by
solid-state strain overprint that lasted more than 100 Myr at
temperatures above those of the brittle domain
Fold uplift versus regional subsidence and sedimentation rate
No full textFold uplifts compete during their development with regional subsidence in the frontal parts of thrust belts and accretionary wedges. Two cases exist in frontal thrust belts. In the first, more common case, the uplift rate of the external folds is higher than the subsidence rate of the foredeep. In the second case the fold uplift is less than the regional subsidence. The total fold uplift may be considered as the fold uplift rate minus the regional subsidence rate; this value can be either positive or negative. Positive total fold uplift occurs when folds rise faster than regional subsidence and the envelope of the fold crest rises towards the hinterland of the accretionary wedge. In the opposite case, negative total fold uplift, the envelope dips towards the hinterland because folds rise more slowly than regional subsidence. In the first positive case, the folds are deeply eroded and the onlap of the growing strata moves away from the fold crest if the sedimentation rate is lower than the fold uplift rate in marine or alluvial environments. In the second negative case, where folds rise at lower rates than the regional subsidence, the onlap moves towards the fold crest if the sedimentation rate is higher than the fold uplift rate. This is also the more favorable case for hydrocarbon traps where growth strata can seal the fold, Moreover the fast subsidence rates in the foredeep provide a higher thermal maturation. This second tectonic setting is commonly associated with accretionary wedges forming along west-directed subduction zones, which are characterized by high subsidence rates in the foredeep or trench, due to the fast 'eastward' roll-back of the subduction hinge (e.g. Apennines, Carpathians,Banda are)
Modelling the thermal perturbation of the continental crust after intraplating of thick granitoid sheets: a comparison with the crustal sections in Calabria (Italy)
No full textThick granitoid sheets represent a considerable percentage of Palaeozoic
crustal sections exposed in Calabria. High thermal gradients are
recorded in upper and lower crustal regional metamorphic rocks lying at
the roof and base of the granitoids. Ages of peak metamorphism and
emplacement of granitoids are mostly overlapping, suggesting a
connection between magma intrusion and low-pressure metamorphism. To
analyse this relationship, thermal perturbation following granitoid
emplacement has been modelled. The simulation indicates that, in the
upper crust, the thermal perturbation is short-lived. In contrast, in
the lower crust temperatures greater than 700degreesC are maintained for
12 Ma, explaining granulite formation, anatexis and the following nearly
isobaric cooling. An even longer perturbation can be achieved
introducing the effect of mantle lithosphere thinning into the model
Alien Registration- Prosser, Bethia G. (Orono, Penobscot County)
No full texthttps://digitalmaine.com/alien_docs/5914/thumbnail.jp
COEXISTENCE OF PSEUDOTACHYLYTE VEINS AND MYLONITIC ZONES AT THE BASE OF THE DEEP CRUST: AN EXAMPLE FROM THE CALABRIA (SOUTHERN ITALY)
No full textNatural examples indicate that pseudotachylytes cohexist in the same
outcrop with mylonites and ultramylonites. Pseudotachylytes intimately
associated with mylonites and ultramylonites can develop in high strain
zone close to the brittle-ductile transition (e.g. Passchier, 1982) or entirely
within the ductile regime as result of plastic instabilities (e.g. Hobbs et al.,
1986; Handy & Brun, 2004).
This study report microstructural investigations on two pseudotachylyte
veins found within the felsic granulites at the base of the ~20-25 km thick
Variscan crustal section outcropping in the Serre Massif (southern
Calabria). Felsic granulites consist of quartz, plagioclase, K-feldspar,
biotite, garnet, sillimanite and accessory minerals. Stretched minerals and
S-C composite foliations are detected in zones crystal-plastic deformation.
In places, felsic granulites exhibit an alternance of mylonitic and
ultramylonitic bands (a few millimeters thick). Pseudotachylyte fault-veins
develop along planes, which have a parallel orientation to the mylonitic
and/or ultramylonitic foliation. Locally, pseudotachylyte fault-veins occur
along the S-C composite foliations of the felsic granulite. On the other
hand, the pseudotachylyte injection-veins cross cut the mylonitic and/or
ultramylonitic bands.
Microstructural observations indicate that the felsic granulite exhibits a
strong grain-size reduction along the S-C composite foliations and near
the contact with the pseudotachylyte veins. Back scattered electron (BSE)
images, obtained by scanning electron microscopy (SEM) and
Field-Emission Gun SEM, show that in proximity of the contact with the
pseudotachylyte the garnet of the felsic granulite is fractured and shows
rims characterized by a new cristallization of very small euhedral garnet
(3-4 m). On the other hand, the ultramylonitic bands display a very
fine-grained matrix and have a dark appearance. However, the BSE
images reveal a strong penetrative foliation, which is defined by the
alignment of biotite and by the shape preferred orientation of quartz,
plagioclase and garnet. Moreover, the ultramylonitic bands are
characterized by a new crystallization of very small crystals (a few microns
in length) of sillimanite and K-feldspar, aligned along the foliation planes.
Matrix of the pseudotachylytes is microcrystalline and contains abundant
clasts (>50%) made up of quartz, plagioclase, K-feldspar, garnet and rare
biotite. Clasts in the matrix are aligned with a parallel orientation to
oblique foliation of the mylonitic granulite. At the margin of the vein,
garnet of the pseudotachylyte may occur in two habits: 1) garnet
microlites with very small sizes (3-4 m) and an idiomorph habit, which
formed by direct crystallization from the frictional melt, and 2) garnet
clasts (a few ten micrometres in size), with rims characterized by a new
crystallization of very small garnets (<2 m) and with a similar aspect to
the garnet rims of the host rock. In the vein centre, the matrix is mainly
composed of skeletal plagioclase and biotite (a few microns in lenght).
Plagioclase and biotite microlites often nucleated on rounded clasts of
quartz or plagioclase. Garnet microlites are absent in the vein centre.
These data, combined with the indications for the formation depth of the
pseudotachylytes (21-23 km) obtained by Altenberger et al. (2010),
indicate that during propagation of the seismic rupture the shear
deformation was highly heterogeneous and took place through the
development of alternating pseudotachylyte and ultramylonite, as result of
plastic instabilities.
References
Altenberger, U., Prosser, G. & Grande, A. (2010): Workshop
Physico-chemical processes in seismic faults, 11
Handy, M.R. & Brun, J.P. (2004): Earth Planet. Sc. Lett., 223, 427-441
Hobbs, B.E., Ord, A. & Teyssier, C. (1986): Pure Appl. Geophys., 124,
309-336
Passchier, C.W. (1982): J. Struct. Geol., 4, 69-7
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