INVESTIGADORES
CRISTALLINI ernesto Osvaldo
artículos
Título:
Thick-skinned and thin-skinned thrusting in La Ramada fold and thrust belt : Crustal evolution of the High Andes of San Juan, Argentina (32° SL).
Autor/es:
CRISTALLINI, E.O.; RAMOS, V.A.
Revista:
TECTONOPHYSICS
Editorial:
Elsevier Ltd.
Referencias:
Año: 2000 vol. 317 p. 205 - 235
ISSN:
0040-1951
Resumen:
The Cenozoic structural evolution of the La Ramada fold and thrust belt in the High Andes of Argentina, between
32°00¾S and 32°30¾S, shows in time and space the interaction of thin-skinned and thick-skinned deformations. Based
on geometric and kinematic constraints, three different deformation stages have been recognized. The first began with
thin-skinned NNW-trending structures detached in Upper Jurassic gypsum. In the second stage, the basement was
involved by tectonic inversion of Triassic normal faults producing a thick-skinned fold and thrust belt. This inversion,
combined with the ductile rheology of the Jurassic gypsum, resulted in refolding of older structures. The uplift of the
basement by high-angle reverse faults at the RamadaEspinacito Massif, produced a sticking point in the foreland
propagation of the thrust belt. This was responsible for the third stage of deformation characterized by thin-skinned
NNW out-of-sequence thrusts developed in the westernmost sector. The total Andean shortening calculated in the
area was 2124 km (near 30%). The structure of the La Ramada fold and thrust belt was integrated into a crustalscale
cross-section at 32°S latitude. Based on gravimetric models and surface geology, a crustal model is proposed for
the Andes of Chile and Argentina. A shortening of 180 km was calculated between the Chile trench and the Sierra
de Pie de Palo. This implies a mean deformation rate of 2.8 mm year−1 during Cenozoic times. An initial crustal
thickness of ca. 33 km was computed. A two-layer model with a middle detachment level is proposed to explain the
spatial decoupling between maximum shortening at the surface and maximum crustal thickening. The upper layer
was balanced based on surface structural information. The lower layer is interpreted to have been constructed by an
imbricate thrust system controlled by the Mercedario rift master-shear and the PrecordilleraChilenia suture.°00¾S and 32°30¾S, shows in time and space the interaction of thin-skinned and thick-skinned deformations. Based
on geometric and kinematic constraints, three different deformation stages have been recognized. The first began with
thin-skinned NNW-trending structures detached in Upper Jurassic gypsum. In the second stage, the basement was
involved by tectonic inversion of Triassic normal faults producing a thick-skinned fold and thrust belt. This inversion,
combined with the ductile rheology of the Jurassic gypsum, resulted in refolding of older structures. The uplift of the
basement by high-angle reverse faults at the RamadaEspinacito Massif, produced a sticking point in the foreland
propagation of the thrust belt. This was responsible for the third stage of deformation characterized by thin-skinned
NNW out-of-sequence thrusts developed in the westernmost sector. The total Andean shortening calculated in the
area was 2124 km (near 30%). The structure of the La Ramada fold and thrust belt was integrated into a crustalscale
cross-section at 32°S latitude. Based on gravimetric models and surface geology, a crustal model is proposed for
the Andes of Chile and Argentina. A shortening of 180 km was calculated between the Chile trench and the Sierra
de Pie de Palo. This implies a mean deformation rate of 2.8 mm year−1 during Cenozoic times. An initial crustal
thickness of ca. 33 km was computed. A two-layer model with a middle detachment level is proposed to explain the
spatial decoupling between maximum shortening at the surface and maximum crustal thickening. The upper layer
was balanced based on surface structural information. The lower layer is interpreted to have been constructed by an
imbricate thrust system controlled by the Mercedario rift master-shear and the PrecordilleraChilenia suture.fferent deformation stages have been recognized. The first began with
thin-skinned NNW-trending structures detached in Upper Jurassic gypsum. In the second stage, the basement was
involved by tectonic inversion of Triassic normal faults producing a thick-skinned fold and thrust belt. This inversion,
combined with the ductile rheology of the Jurassic gypsum, resulted in refolding of older structures. The uplift of the
basement by high-angle reverse faults at the RamadaEspinacito Massif, produced a sticking point in the foreland
propagation of the thrust belt. This was responsible for the third stage of deformation characterized by thin-skinned
NNW out-of-sequence thrusts developed in the westernmost sector. The total Andean shortening calculated in the
area was 2124 km (near 30%). The structure of the La Ramada fold and thrust belt was integrated into a crustalscale
cross-section at 32°S latitude. Based on gravimetric models and surface geology, a crustal model is proposed for
the Andes of Chile and Argentina. A shortening of 180 km was calculated between the Chile trench and the Sierra
de Pie de Palo. This implies a mean deformation rate of 2.8 mm year−1 during Cenozoic times. An initial crustal
thickness of ca. 33 km was computed. A two-layer model with a middle detachment level is proposed to explain the
spatial decoupling between maximum shortening at the surface and maximum crustal thickening. The upper layer
was balanced based on surface structural information. The lower layer is interpreted to have been constructed by an
imbricate thrust system controlled by the Mercedario rift master-shear and the PrecordilleraChilenia suture.%). The structure of the La Ramada fold and thrust belt was integrated into a crustalscale
cross-section at 32°S latitude. Based on gravimetric models and surface geology, a crustal model is proposed for
the Andes of Chile and Argentina. A shortening of 180 km was calculated between the Chile trench and the Sierra
de Pie de Palo. This implies a mean deformation rate of 2.8 mm year−1 during Cenozoic times. An initial crustal
thickness of ca. 33 km was computed. A two-layer model with a middle detachment level is proposed to explain the
spatial decoupling between maximum shortening at the surface and maximum crustal thickening. The upper layer
was balanced based on surface structural information. The lower layer is interpreted to have been constructed by an
imbricate thrust system controlled by the Mercedario rift master-shear and the PrecordilleraChilenia suture.°S latitude. Based on gravimetric models and surface geology, a crustal model is proposed for
the Andes of Chile and Argentina. A shortening of 180 km was calculated between the Chile trench and the Sierra
de Pie de Palo. This implies a mean deformation rate of 2.8 mm year−1 during Cenozoic times. An initial crustal
thickness of ca. 33 km was computed. A two-layer model with a middle detachment level is proposed to explain the
spatial decoupling between maximum shortening at the surface and maximum crustal thickening. The upper layer
was balanced based on surface structural information. The lower layer is interpreted to have been constructed by an
imbricate thrust system controlled by the Mercedario rift master-shear and the PrecordilleraChilenia suture.−1 during Cenozoic times. An initial crustal
thickness of ca. 33 km was computed. A two-layer model with a middle detachment level is proposed to explain the
spatial decoupling between maximum shortening at the surface and maximum crustal thickening. The upper layer
was balanced based on surface structural information. The lower layer is interpreted to have been constructed by an
imbricate thrust system controlled by the Mercedario rift master-shear and the PrecordilleraChilenia suture.