15 research outputs found
Stress field and active faults in the orogenic front of the Andes in the MalargĂŒe fold-and-thrust belt (35°â36°S)
We integrate field and wellbore data to discuss the stress field in the frontal sector of the MalargĂŒe fold-and-thrust belt (Andes of Argentina). Surface observations indicate N-S thrusts and NW to WNW and ESE strike-slip faults are active in the study area. Inversion of fault kinematic indicators, combined with borehole breakout data and a mini-frac test within the study area, constrain the Quaternary to recent stress state, which is characterized by a subhorizontal, E-W oriented maximum stress, and by intermediate and minimum stresses with similar magnitudes that are locally interchanged, producing a setting in which reverse and strike-slip faults are alternatively active. The implications of the recognized structures for earthquake hazard are examined.Fil: Mescua, Jose Francisco. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales; ArgentinaFil: Barrionuevo, MatĂas. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales; ArgentinaFil: Giambiagi, Laura Beatriz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales; ArgentinaFil: Suriano, Julieta. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales; ArgentinaFil: Spagnotto, Silvana Liz. Universidad Nacional de San Luis. Facultad de Ciencias FĂsico MatemĂĄticas y Naturales. Departamento de FĂsica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Stahlschmidt, E.. El TrĂ©bol S.a.; ArgentinaFil: de la Cal, H.. Roch S.a.; ArgentinaFil: Soto, J. L.. Roch S.a.; ArgentinaFil: Mazzitelli, Manuela Amelia. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de NivologĂa, GlaciologĂa y Ciencias Ambientales; Argentin
The structure of Chariklo's rings from stellar occultations
Two narrow and dense rings (called C1R and C2R) were discovered around the
Centaur object (10199) Chariklo during a stellar occultation observed on 2013
June 3. Following this discovery, we planned observations of several
occultations by Chariklo's system in order to better characterize the physical
properties of the ring and main body. Here, we use 12 successful occulations by
Chariklo observed between 2014 and 2016. They provide ring profiles (physical
width, opacity, edge structure) and constraints on the radii and pole position.
Our new observations are currently consistent with the circular ring solution
and pole position, to within the km formal uncertainty for the ring
radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal
significant width variations from to 7.5 km. The width of the fainter
ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and
outer edges of C1R are consistent with infinitely sharp boundaries, with
typical upper limits of one kilometer for the transition zone between the ring
and empty space. No constraint on the sharpness of C2R's edges is available. A
1 upper limit of m is derived for the equivalent width of
narrow (physical width <4 km) rings up to distances of 12,000 km, counted in
the ring plane
A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS measured from stellar occultations
This work aims at constraining the size, shape, and geometric albedo of the
dwarf planet candidate 2002 MS4 through the analysis of nine stellar
occultation events. Using multichord detection, we also studied the object's
topography by analyzing the obtained limb and the residuals between observed
chords and the best-fitted ellipse. We predicted and organized the
observational campaigns of nine stellar occultations by 2002 MS4 between 2019
and 2022, resulting in two single-chord events, four double-chord detections,
and three events with three to up to sixty-one positive chords. Using 13
selected chords from the 8 August 2020 event, we determined the global
elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the
object's rotational information from the literature, constrains the object's
size, shape, and albedo. Additionally, we developed a new method to
characterize topography features on the object's limb. The global limb has a
semi-major axis of 412 10 km, a semi-minor axis of 385 17 km, and
the position angle of the minor axis is 121 16. From
this instantaneous limb, we obtained 2002 MS4's geometric albedo and the
projected area-equivalent diameter. Significant deviations from the fitted
ellipse in the northernmost limb are detected from multiple sites highlighting
three distinct topographic features: one 11 km depth depression followed by a
25 km height elevation next to a crater-like depression with an
extension of 322 39 km and 45.1 1.5 km deep. Our results present an
object that is 138 km smaller in diameter than derived from thermal
data, possibly indicating the presence of a so-far unknown satellite. However,
within the error bars, the geometric albedo in the V-band agrees with the
results published in the literature, even with the radiometric-derived albedo
A ring system detected around the Centaur (10199) Chariklo
Until now, rings have been detected in the Solar System exclusively around the four giant planets. Here we report the discovery of the rst minor-body ring system around the Centaur object (10199) Chariklo, a body with equivalent radius 124±9 km. A multi-chord stellar occultation revealed the presence of two dense rings around Chariklo, with widths of about 7 km and 3 km, optical depths 0.4 and 0.06, and orbital radii 391 and 405 km, respectively. The present orientation of the ring is consistent with an edge-on geometry in 2008, thus providing a simple explanation for the dimming of Chariklo's system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partially composed of water ice. These rings may be the remnants of a debris disk, which were possibly con ned by embedded kilometre-sized satellites
Three-dimensional approach to understanding the relationship between the Plio-Quaternary stress field and tectonic inversion in the Triassic Cuyo Basin, Argentina
The Cacheuta sub-basin of the Triassic Cuyo Basin is an example of
rift basin inversion contemporaneous to the advance of the Andean
thrust front, during the PlioâQuaternary. This basin is one of the
most important sedimentary basins in a much larger Triassic
NNW-trending depositional system along the southwestern margin of the
Pangea supercontinent. The amount and structural style of inversion is
provided in this paper by a three-dimensional approach to the
relationship between inversion of rift-related structures and spatial
variations in late Cenozoic stress fields.
The PlioâQuaternary stress field exhibits important NâS variations in
the foreland area of the southern Central Andes, between 33 and
34° S, with a southward gradual change from pure
compression, with σ1 and σ2 being horizontal, to
a strike-slip type stress field, with σ2 being vertical.
We present a 3-D approach for studying the tectonic inversion of the
sub-basin master fault associated with strike-slipâreverse to
strike-slip faulting stress regimes. We suggest that the inversion of
Triassic extensional structures, striking NNW to WNW, occurred during
the PlioâPleistocene in those areas with strike-slipâreverse to
strike-slip faulting stress regime, while in the reverse faulting
stress regime domain they remain fossilized. Our example demonstrates
the impact of the stress regime on the reactivation pattern along the
faults
Waveform inversion and focal mechanisms of two weak earthquakes in Cordillera Principal (Argentina) between 35° and 35.5° S
Only few (six) focal mechanism, in CMT Catalog, have been so far known for intraplate shallow events in the Andean chain close to ChileâArgentina state border at latitudes âŒ35° S. We add two more mechanisms, depths and moment magnitudes by carefully analyzing full waveforms of weak events recorded by broad-band stations of the Chile Argentina Geophysical Experiment (southern profile). The moment magnitudes of both events (Mw = 3.6 and 3.7) are lower than the duration magnitudes (Md = 4.0 and 4.29) reported by NEIC. The source depth, constrained by waveforms for one of the studied events (5.5â8.5 km) seems to be considerably shallower than the hypocenter depth located by means of arrival times (âŒ20 km). The waveform analysis was complemented by first-motion polarities which resulted in an uncertainty assessment of the focal mechanism. Event 1 (2001-11-03) has a strike-slip mechanism with a small normal component and almost vertical nodal planes in the north-south and east-west directions. The north-south nodal plane could be related to the Calabozos faults system. Event 2 (2002-02-16) has a strike-slip mechanism with a small thrust component. The latter event (its subhorizontal nodal plane) could be associated with the El Diablo-El Fierro fault system. Dextral strike-slip solutions are consistent with recent studies in the area.Fil: Villegas Alvarez, Raquel Judith. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂsicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: ZahradnĂk, Jiri. Karlova Univerzita (cuni); RepĂșblica ChecaFil: Nacif Suvire, Silvina Valeria. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, FĂsicas y Naturales. Instituto GeofĂsico SismolĂłgico Volponi; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan; ArgentinaFil: Spagnotto, Silvana Liz. Universidad Nacional de San Luis. Facultad de Ciencias FĂsico MatemĂĄticas y Naturales. Departamento de FĂsica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Luis; ArgentinaFil: Winocur, Diego Alejandro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de GeologĂa. Laboratorio de TectĂłnica Andina; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Leiva, Maria Flavia. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, FĂsicas y Naturales. Instituto GeofĂsico SismolĂłgico Volponi; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan; Argentin
The Trans-Neptunian Object (84922) 2003 VS 2 through Stellar Occultations
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