Capítulos de Libros

Geomorfología

CANDIANI; CARIGNANO; STUART-SMITH; LYONS; MIRO; LOPEZ

Hoja Geológica 3166-II, Cruz del Eje. Provincias de Córdoba, La Rioja y Catamarca.

Instituto de Geología y Recursos Minerales, Servicio Geológico Minero Argentino., Buenos Aires

Año:2001 p.62-69

Geological Sheet 3166-II, CRUZ DEL EJE is located in Córdoba province and encompasses the northern portion of the hilly ridges named Sierra Gran-de and Sierra Chica and part of the large salt-lake known as Salinas Grandes. The study region is part of the southern Sierras Pampeanas, which is a distinctive morphotectonic province composed of early to mid-Paleozoic metamorphic and igneous tilted-blocks. The Pampean domain comprises a suite of metamorphic units intruded by Cambrian, Ordovician, and Devonian granitoids and includes major shear zones, such as the Guamanes Shear Zone. The oldest exposures are mainly metapelites, calc-silicate rocks and marbles with minor amphibolites, which reached amphibolite grade conditions (M1; high temperature, low pressure) with localized migmatization approximately 530 million years ago. Local melting produced a series of S-type granites, which probably crystallized about 10 to 15 million years later. The early Cambrian Complejo Ígneo Ascochinga comprises tonalites, granodiorites, monzogranites and minor paragneisses with a crystallization age of about 515 Ma. The protolith sediments accumulated on the western passive margin of Gondwana, which developed during the separation of Laurentia from Gondwana and the formation of the Iapetus Ocean at about 540 Ma. Following intrusion of mafic dykes, progressive deformation (D1) and metamorphism (M1) produced penetrative foliation, which in turn is associated with tectonic activity developed during the Pampean cycle. In the lower Ordovician (490-470 Ma), com-pressive deformation followed by extension (D2) and metamorphism of amphibolite-greenschist grade (M2) resulted in tight folding (D1) and development of gneissic fabrics in the unit named Complejo Ígneo Ascochinga. Thrusting of west-vergence and tectonic activity along the Guamanes Shear Zone probably occurred at this time. In addition, the phyric granites of the Guamanes Shear Zone are interpreted to be emplaced during extension at about 470 Ma. The Ordovician deformation known as the Famatinian cycle is linked with the closure of the Iapetus Ocean and eastward subduction beneath the Gondwana continent. In the lower Devonian, the active convergence along the Gondwana margin during the Achalian cycle, resulted in the reactivation of the Guamanes Shear Zone, isoclinal folding of earlier fabrics (D3) and metamorphism of greenschist facies (M3). In addition, the development of a magmatic arc promoted the generation of large volumes of felsic magma from partial melting of a MgO depleted crust. It is worth noting that airborne magnetic surveys suggest that a series of granitic plutons are emplaced near the surface or are buried beneath Cenozoic cover, such as the small bodies located to the south of the Capi-lla del Monte, which are apophyses of a larger plutonic body. Based on 40 Ar-39 Ar dates from the Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-39 40 Ar-39 Ar dates from the Guamanes Shear Zone, the Achalian cycle exten-ded throughout the Devonian. Peneplanation of the basement was followed by deposition of the Carboniferous-Permian Panganzo Group, which comprises fluvio-lacustrine sediments preserved in a graben named Tasa Cuna located in the northwestern portion of the quadrangle. This structure probably developed in the late Paleozoic and was active until Cretaceous times when exten-sional processes recorded by the Punilla and La Calera faults promoted the formation of half-grabens. Deposition of nonmarine clastic strata was associated with extrusion of mafic lavas. The present-day topography is due to Plio-Pleistocene block tilting of the crystalline basement during the Andean orogenic cycle. Uplift occurred on moderate to steeply dipping reverse faults. The most important ore deposits are genetically linked with the Achalian tectonic cycle (Devonian). There are several deposits bearing gold, wolfram, silver, lead, zinc and copper, which are associated with a second period of mineralization represented by pegmatites bearing beryl, lithium, thallium, uranium, thorium, phosphorus and rare earth elements. In addition, there are gold-bearing quartz veins associated with shear zones in the Candelaria district, silver-lead-zinc quartz veins in the El Guaico district and wolfram-bearing quartz veins near Aguas de Ramón area. Epigenetic wolfram-copper deposits mainly hosted by calc-silicate rocks to the west of Capilla del Monte (e.g., El Zinqui) are interpreted to be formed during the Achalian phase. New 40 Ar-3940 Ar-39 Ar dating of white mica from gold-copper-wolfram and gold-lead-zinc veins suggests that mineralization occurred between 390 and 360 Ma.