Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland
In the northern part of the Calchaquí Valley (NW Argentina), Palaeogene Andean foreland sediments are represented by a 1400-metre-thick continental succession (QLC: Quebrada de Los Colorados Formation) consisting of claystones, siltstones, sandstones, and conglomerates representing sedimentation in...
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2014
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v52_n_p43_DoCampo http://hdl.handle.net/20.500.12110/paper_08959811_v52_n_p43_DoCampo |
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paper:paper_08959811_v52_n_p43_DoCampo2023-06-08T15:48:44Z Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland Do Campo, Margarita Diana Diagenesis Foreland basins Illite/smectite mixed-layers Kaolinite NW Argentina Cenozoic diagenesis facies analysis foreland basin geothermal gradient illite kaolinite Paleogene sedimentation smectite tectonic evolution tectonic setting X-ray diffraction Argentina Calchaqui Valleys Micas In the northern part of the Calchaquí Valley (NW Argentina), Palaeogene Andean foreland sediments are represented by a 1400-metre-thick continental succession (QLC: Quebrada de Los Colorados Formation) consisting of claystones, siltstones, sandstones, and conglomerates representing sedimentation in fluvial-alluvial plains and alluvial fan settings. To understand the main syn- and postsedimentary variables controlling the clay mineral assemblages of this succession, we have studied the fine-grained clastic sediments by X-ray diffraction and electron microscopy, along with a detailed sedimentary facies analysis, for two representative sections. In the northern section, the whole succession was sampled and analysed by XRD, whereas in the second section, a control point 15km to the south, only the basal levels were analysed. The XRD study revealed a strong contrast in clay mineral assemblages between these two sections as well as with sections in the central Calchaquí Valley studied previously. In the northernmost part of the study area, a complete evolution from smectite at the top to R3 illite/smectite mixed-layers plus authigenic kaolinite at the bottom, through R1-type mixed-layers in between, has been recognized, indicating the attainment of late diagenesis. In contrast, the clay mineral assemblages of equivalent foreland sediments cropping out only 15km to the south contain abundant smectite and micas, subordinate kaolinite and chlorite, and no I/S mixed-layers to the bottom of the sequence. Early diagenetic conditions were also inferred in a previous study for equivalent sediments of the QLC Formation cropping out to the south, in the central Calchaquí Valley, as smectite occurs in basal strata. Burial depths of approximately 3000m were estimated for the QLC Formation in the central and northern Calchaquí Valley; in addition, an intermediate to slightly low geothermal gradient can be considered likely for both areas as foreland basins are regarded as hypothermal basins. Consequently, the attainment of late diagenesis in the northernmost study area cannot be explained by significant differences in burial depth nor in geothermal gradient in relation to the section 15km to the south nor with the central Calchaquí Valley. The formation of R3 mixed-layer I/S and authigenic kaolinite in the northern study area was most likely controlled by the circulation of hot, deep fluids along the reverse faults that bounded the Calchaquí valley. These faults were active during the Cenozoic, as evidenced by the syndepositional deformation features preserved in the studied sediments. Stress could also have been a driving force in burial diagenesis at the R3 mixed-layer I/S stage in these young continental sediments. © 2014 Elsevier Ltd. Fil:Do Campo, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2014 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v52_n_p43_DoCampo http://hdl.handle.net/20.500.12110/paper_08959811_v52_n_p43_DoCampo |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Diagenesis Foreland basins Illite/smectite mixed-layers Kaolinite NW Argentina Cenozoic diagenesis facies analysis foreland basin geothermal gradient illite kaolinite Paleogene sedimentation smectite tectonic evolution tectonic setting X-ray diffraction Argentina Calchaqui Valleys Micas |
| spellingShingle |
Diagenesis Foreland basins Illite/smectite mixed-layers Kaolinite NW Argentina Cenozoic diagenesis facies analysis foreland basin geothermal gradient illite kaolinite Paleogene sedimentation smectite tectonic evolution tectonic setting X-ray diffraction Argentina Calchaqui Valleys Micas Do Campo, Margarita Diana Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland |
| topic_facet |
Diagenesis Foreland basins Illite/smectite mixed-layers Kaolinite NW Argentina Cenozoic diagenesis facies analysis foreland basin geothermal gradient illite kaolinite Paleogene sedimentation smectite tectonic evolution tectonic setting X-ray diffraction Argentina Calchaqui Valleys Micas |
| description |
In the northern part of the Calchaquí Valley (NW Argentina), Palaeogene Andean foreland sediments are represented by a 1400-metre-thick continental succession (QLC: Quebrada de Los Colorados Formation) consisting of claystones, siltstones, sandstones, and conglomerates representing sedimentation in fluvial-alluvial plains and alluvial fan settings. To understand the main syn- and postsedimentary variables controlling the clay mineral assemblages of this succession, we have studied the fine-grained clastic sediments by X-ray diffraction and electron microscopy, along with a detailed sedimentary facies analysis, for two representative sections. In the northern section, the whole succession was sampled and analysed by XRD, whereas in the second section, a control point 15km to the south, only the basal levels were analysed. The XRD study revealed a strong contrast in clay mineral assemblages between these two sections as well as with sections in the central Calchaquí Valley studied previously. In the northernmost part of the study area, a complete evolution from smectite at the top to R3 illite/smectite mixed-layers plus authigenic kaolinite at the bottom, through R1-type mixed-layers in between, has been recognized, indicating the attainment of late diagenesis. In contrast, the clay mineral assemblages of equivalent foreland sediments cropping out only 15km to the south contain abundant smectite and micas, subordinate kaolinite and chlorite, and no I/S mixed-layers to the bottom of the sequence. Early diagenetic conditions were also inferred in a previous study for equivalent sediments of the QLC Formation cropping out to the south, in the central Calchaquí Valley, as smectite occurs in basal strata. Burial depths of approximately 3000m were estimated for the QLC Formation in the central and northern Calchaquí Valley; in addition, an intermediate to slightly low geothermal gradient can be considered likely for both areas as foreland basins are regarded as hypothermal basins. Consequently, the attainment of late diagenesis in the northernmost study area cannot be explained by significant differences in burial depth nor in geothermal gradient in relation to the section 15km to the south nor with the central Calchaquí Valley. The formation of R3 mixed-layer I/S and authigenic kaolinite in the northern study area was most likely controlled by the circulation of hot, deep fluids along the reverse faults that bounded the Calchaquí valley. These faults were active during the Cenozoic, as evidenced by the syndepositional deformation features preserved in the studied sediments. Stress could also have been a driving force in burial diagenesis at the R3 mixed-layer I/S stage in these young continental sediments. © 2014 Elsevier Ltd. |
| author |
Do Campo, Margarita Diana |
| author_facet |
Do Campo, Margarita Diana |
| author_sort |
Do Campo, Margarita Diana |
| title |
Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland |
| title_short |
Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland |
| title_full |
Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland |
| title_fullStr |
Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland |
| title_full_unstemmed |
Syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, Andean Argentinean foreland |
| title_sort |
syn- and post-sedimentary controls on clay mineral assemblages in a tectonically active basin, andean argentinean foreland |
| publishDate |
2014 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v52_n_p43_DoCampo http://hdl.handle.net/20.500.12110/paper_08959811_v52_n_p43_DoCampo |
| work_keys_str_mv |
AT docampomargaritadiana synandpostsedimentarycontrolsonclaymineralassemblagesinatectonicallyactivebasinandeanargentineanforeland |
| _version_ |
1768541852469821440 |