237 research outputs found
Did differences in composition and strength of subducted sediment define the rupture of the great 1960 Chile earthquake?
Tracking the provenance - assessing sedimentary pathways and upper plate dynamics at the South Central Chile margin
Did differences in strength and frictional behaviour of subducted sediment constrain the rupture of the great 1960 Chile earthquake?
Data report: preliminary assessment of Pleistocene sediment strength in the Ursa Basin (Gulf of Mexico continental slope) from triaxial and ring shear test data
We report the preliminary results of a triaxial and ring shear study
on clay-rich, fine-grained Pleistocene sediments cored in Ursa Basin,
Gulf of Mexico continental slope. Specimens from Integrated
Ocean Drilling Program (IODP) Expedition 308 Sites U1322 and
U1324 document friction coefficients in the range of 0.13–0.31,
with internal angles of friction of ~7.4°–17.2° in ring shear experiments.
At intermediate (7.624 MPa) to high (15.237 MPa) overburden
pressure, the majority of the samples tested show velocity
weakening, whereas lower overburden pressures do not give a
clear trend regarding velocity weakening or strengthening of the
samples. In consolidated-undrained triaxial tests, peak shear
stresses observed are between 27 and 140 kPa, with the strongest
sample by far coming from a core catcher section. We suspect that
this is an effect of fabric changes induced during hydraulic piston
coring. One sample coming from the base of a mass transport deposit
at Site U1322 is the weakest one tested. Young’s moduli calculated
range from 2 to 17.4 kPa. Stress paths indicate slight overconsolidation
of the samples, which is in line with the
information gained from preconsolidation stresses in other studies.
Permeability determined from consolidation data is in the
range of 10–16 to 10–17 m2, and hydraulic conductivity is around
10–9 to 10–10 ms–1. Grain density of the tested samples is around
2.7 g/cm3, and water content ranges from 18.3% to 30.7%
Geologie und Strukturentwicklung der Blankuskopf- und Wildberggruppe im südlichen Brandnertal (Rätikon, Österreich)
Detailed geological mapping and structural analysis of the Blankuskopf- and
Wildberggroup in the Rätikon area (Vorarlberg/Austria) was carried out in the
framework of a Diploma-thesis at the University of Freiburg.
The full stratigraphy of the Northen Calcareous Alps (NCA) can be found
in the area, starting with the skythian Bundsandstein and continuing up to the
upper Cretaceous Kreideschiefer, as well as lithologies from the south-Penninic
Arosazone.
The structural style of the mapping area is characterized by many folds and
thrusts and shows two mean features:
1) From the lower to the higher tectonic unit and from NW to SE there is a
change in transport direction from NW via N to NE. This change is linked to a
clockwise rotation of each unit with respect to its underlying unit.
2) Within each unit there is a change in transport direction from NW in its western
part to N in its eastern part. This is especially pronounced in the well-conserved
unit of the Blankuskopfgroup.
The structures are the result of horizontal shortening as well as dextral shearing.
The latter is represented by the fl exing of fold-axes and clockwise rotation
Young sediments from the Southern Chile Trench: a record of active margin magmatism, tectonics, and paleoseismicity
Mass wasting at the base of the South central Chilean continental margin: the Reloca Slide
Offshore south central Chile (35° S–42° S), the morphology of the lowermost continental slope and trench floor witnesses a voluminous submarine mass-wasting event. The blocky slide body deposited in the Chile Trench at 73°46´ W 35°35´ S was targeted for study during RRS JAMES COOK Cruise JC23 and termed Reloca Slide. Its size of about 24 km3, its steep and high headscarp, the spatial distribution of slide deposits and the cohesive nature of major slide blocks make it interesting to address the issue of tsunami generation. We have obtained seismic reflection data that partly reveal the internal structure of the slide body. Gravity core samples were retrieved that will allow the slide to be dated and linked to the history of sedimentation and slope stability along this particular segment of the Chilean convergent margin. At present we assume a Holocene age for the sliding event
Mass wasting as major agent of shaping the morphology of the Southern Central Chilean continental margin
Mass wasting-related morphology of the Southern Central Chilean continental margin - quantitative comparison with other active margins
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