Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement
The Renca Batholith belongs to a group of post-collisional plutons that intruded the Early Paleozoic basement of the Sierra de San Luis during Late Devonian to Early Carboniferous. Combined microstructural, petrofabric and anisotropy of magnetic susceptibility (AMS) studies indicate that interaction...
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2002
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00244937_v61_n3-4_p161_DeLuchi http://hdl.handle.net/20.500.12110/paper_00244937_v61_n3-4_p161_DeLuchi |
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paper:paper_00244937_v61_n3-4_p161_DeLuchi2023-06-08T14:52:29Z Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement Rapalini, Augusto Ernesto Geuna, Silvana Evangelina Argentina Emplacement Magnetic fabrics Renca Batholith Rock fabrics Sierras Pampeanas South America Texture batholith deformation Devonian emplacement magmatism magnetic susceptibility microstructure petrofabric Argentina The Renca Batholith belongs to a group of post-collisional plutons that intruded the Early Paleozoic basement of the Sierra de San Luis during Late Devonian to Early Carboniferous. Combined microstructural, petrofabric and anisotropy of magnetic susceptibility (AMS) studies indicate that interactions between magmatism and emplacement related fabrics played the main role in the strain patterns with a very subordinate far field control by regional deformation. This concentrically foliated zoned elliptical granitoid is made up by porphyric granodiorites and equigranular monzogranites that are associated with syenites and monzonites. Two major magmatic associations are present: (i) a Mg-K monzonitic association represented by syenitic, monzonitic and monzodioritic enclaves and synplutonic dykes and a porphyroid monzodioritic to melagranodioritic facies and (ii) a high K calc-alkaline association that constitutes the major part of the concentrically zoned batholith with an external porphyroid granodiorite to monzogranite (Unit 1) and a central equigranular monzogranite (Unit 2). Bulk susceptibility (K) shows a bimodal distribution that corresponds, respectively, to Unit 1 (ferromagnetic) and Unit 2 (paramagnetic). Similar distribution is observed in the intensity of natural remanent magnetization (NRM) and AMS degree (P'). The steep to vertical inward dipping foliation that is recognized in the porphyroid granitoids is parallel to the X-Y flattening plane of the enclaves, the synplutonic dykes attitude and the contact between the two major units of the batholith. The AMS defines a predominantly foliated fabric, with a distribution of magnetic foliation planes generally subvertical and parallel to the boundaries of the ring-like Unit 1. These internal features are concordant with the axial planes of the meso- and microscale folding of the regional NNE S2/S3 in the ductile aureole that developed in the medium grade metamorphic Ordovician country rocks. Foliation results from a combination of both magmatic and high-temperature solid-state flows; the latter as the result of the emplacement of the central monzogranite, which caused a radial compression. K ≈ O as measured using strain indicators suggests flattening. Unit 2 shows a planar magnetic fabric shallowly dipping outwards and dominant subhorizontal lineations. The magnetic fabrics of this body agree with other fabric parameters and are consistent with a magmatic fabric. There is a strong correlation between rock and magnetic fabrics. These fabrics reflect internal magma dynamics whereas regional tectonic exerted a far field control on the expansion of the pluton. © 2002 Elsevier Science B.V. All rights reserved. Fil:Rapalini, A.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Geuna, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2002 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00244937_v61_n3-4_p161_DeLuchi http://hdl.handle.net/20.500.12110/paper_00244937_v61_n3-4_p161_DeLuchi |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Argentina Emplacement Magnetic fabrics Renca Batholith Rock fabrics Sierras Pampeanas South America Texture batholith deformation Devonian emplacement magmatism magnetic susceptibility microstructure petrofabric Argentina |
| spellingShingle |
Argentina Emplacement Magnetic fabrics Renca Batholith Rock fabrics Sierras Pampeanas South America Texture batholith deformation Devonian emplacement magmatism magnetic susceptibility microstructure petrofabric Argentina Rapalini, Augusto Ernesto Geuna, Silvana Evangelina Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement |
| topic_facet |
Argentina Emplacement Magnetic fabrics Renca Batholith Rock fabrics Sierras Pampeanas South America Texture batholith deformation Devonian emplacement magmatism magnetic susceptibility microstructure petrofabric Argentina |
| description |
The Renca Batholith belongs to a group of post-collisional plutons that intruded the Early Paleozoic basement of the Sierra de San Luis during Late Devonian to Early Carboniferous. Combined microstructural, petrofabric and anisotropy of magnetic susceptibility (AMS) studies indicate that interactions between magmatism and emplacement related fabrics played the main role in the strain patterns with a very subordinate far field control by regional deformation. This concentrically foliated zoned elliptical granitoid is made up by porphyric granodiorites and equigranular monzogranites that are associated with syenites and monzonites. Two major magmatic associations are present: (i) a Mg-K monzonitic association represented by syenitic, monzonitic and monzodioritic enclaves and synplutonic dykes and a porphyroid monzodioritic to melagranodioritic facies and (ii) a high K calc-alkaline association that constitutes the major part of the concentrically zoned batholith with an external porphyroid granodiorite to monzogranite (Unit 1) and a central equigranular monzogranite (Unit 2). Bulk susceptibility (K) shows a bimodal distribution that corresponds, respectively, to Unit 1 (ferromagnetic) and Unit 2 (paramagnetic). Similar distribution is observed in the intensity of natural remanent magnetization (NRM) and AMS degree (P'). The steep to vertical inward dipping foliation that is recognized in the porphyroid granitoids is parallel to the X-Y flattening plane of the enclaves, the synplutonic dykes attitude and the contact between the two major units of the batholith. The AMS defines a predominantly foliated fabric, with a distribution of magnetic foliation planes generally subvertical and parallel to the boundaries of the ring-like Unit 1. These internal features are concordant with the axial planes of the meso- and microscale folding of the regional NNE S2/S3 in the ductile aureole that developed in the medium grade metamorphic Ordovician country rocks. Foliation results from a combination of both magmatic and high-temperature solid-state flows; the latter as the result of the emplacement of the central monzogranite, which caused a radial compression. K ≈ O as measured using strain indicators suggests flattening. Unit 2 shows a planar magnetic fabric shallowly dipping outwards and dominant subhorizontal lineations. The magnetic fabrics of this body agree with other fabric parameters and are consistent with a magmatic fabric. There is a strong correlation between rock and magnetic fabrics. These fabrics reflect internal magma dynamics whereas regional tectonic exerted a far field control on the expansion of the pluton. © 2002 Elsevier Science B.V. All rights reserved. |
| author |
Rapalini, Augusto Ernesto Geuna, Silvana Evangelina |
| author_facet |
Rapalini, Augusto Ernesto Geuna, Silvana Evangelina |
| author_sort |
Rapalini, Augusto Ernesto |
| title |
Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement |
| title_short |
Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement |
| title_full |
Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement |
| title_fullStr |
Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement |
| title_full_unstemmed |
Rock and magnetic fabric of the Renca Batholith (Sierra de San Luis, Argentina): Constraints on emplacement |
| title_sort |
rock and magnetic fabric of the renca batholith (sierra de san luis, argentina): constraints on emplacement |
| publishDate |
2002 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00244937_v61_n3-4_p161_DeLuchi http://hdl.handle.net/20.500.12110/paper_00244937_v61_n3-4_p161_DeLuchi |
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AT rapaliniaugustoernesto rockandmagneticfabricoftherencabatholithsierradesanluisargentinaconstraintsonemplacement AT geunasilvanaevangelina rockandmagneticfabricoftherencabatholithsierradesanluisargentinaconstraintsonemplacement |
| _version_ |
1768544899481731072 |