Micromorphology of paleosols at the continental border of the Buenos Aires province, Argentina
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| Natura: | Artículo científico |
| Lingua: | en |
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Universidad Nacional Autónoma de México
2004
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| _version_ | 1876453843261194240 |
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| author | Andrea Cumba |
| author_facet | Andrea Cumba |
| contents | Micromorphology of paleosols at the continental border of the Buenos Aires province, Argentina Andrea Cumba Perla Imbellone Ciencias de la Tierra Argentina buried soils reworked loess micromorphology The sediments with loessial characteristics of the Pampean plain are called loess y limospampeanos (Pampean loess and silts), to distinguish those of purely eolian origin (loess) from thosereworked by water (silts). In the continental border of La Plata River, mainly loess-like sediments of thelate and middle Pleistocene outcrop, approximately at 20 km from the shoreline. Between that border andthe shoreline they underlie at 25 m depth the Holocene sediments deposited by the regressive events in asuccessive lowering of sea level during the late 6,000 years.The objectives of this work are: a) to integrate previous and new information on several sedimentarysuccessions, b) to study the micromorphological features of the paleosols and c) to carry out a regionalcorrelation of paleosols between the localities of San Pedro and La Plata based on field andmicromorphological features.The profiles are between 18.5 and 12.5 m a.s.l. with macroscopic pedological features which showpartially continuous development. The buried paleosols are superposed and welded, with different degreesof pedogenesis indicated by macro- and micromorphological features of illuviation and hydromorphism.In some cases, these features would have formed simultaneously with the deposition of the eolian dusttrapped by grass. The degree of pedogenesis would depend on the ratio between the intensity of theaccretion and reworking processes, and pedogenesis. The sedimentary units were affected partially ortotally by pedogenesis.Two zones rich in volcanic glass were detected at San Pedro profile; new information reveals thesame situation near La Plata city. The uppermost zone, with 2030% volcanic glass, constitutes in somecases the parent material of the present soil; the deeper zone, contains 5070% volcanic glass.Micromorphological observations confirm the presence of scarce to abundant clasts of old illuvial horizonsand loess embedded in the matrix of most of the paleosols.Pedological processes are most evident in the deeper part of the profiles, indicated by a strong gradeof structure and abundant laminated and juxtaposed textural and amorphous features. The lower paleosolscan be considered pedostratigraphic units useful for correlation in the continental border in northeasternBuenos Aires Province, Argentina. 2004 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57221104 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.1 Vol.21 |
| format | Artículo científico |
| id | redalyc_57221104 |
| institution | Redalyc |
| language | en |
| publishDate | 2004 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Micromorphology of paleosols at the continental border of the Buenos Aires province, Argentina Andrea Cumba Ciencias de la Tierra Argentina buried soils reworked loess micromorphology Micromorphology of paleosols at the continental border of the Buenos Aires province, Argentina Andrea Cumba Perla Imbellone Ciencias de la Tierra Argentina buried soils reworked loess micromorphology The sediments with loessial characteristics of the Pampean plain are called loess y limospampeanos (Pampean loess and silts), to distinguish those of purely eolian origin (loess) from thosereworked by water (silts). In the continental border of La Plata River, mainly loess-like sediments of thelate and middle Pleistocene outcrop, approximately at 20 km from the shoreline. Between that border andthe shoreline they underlie at 25 m depth the Holocene sediments deposited by the regressive events in asuccessive lowering of sea level during the late 6,000 years.The objectives of this work are: a) to integrate previous and new information on several sedimentarysuccessions, b) to study the micromorphological features of the paleosols and c) to carry out a regionalcorrelation of paleosols between the localities of San Pedro and La Plata based on field andmicromorphological features.The profiles are between 18.5 and 12.5 m a.s.l. with macroscopic pedological features which showpartially continuous development. The buried paleosols are superposed and welded, with different degreesof pedogenesis indicated by macro- and micromorphological features of illuviation and hydromorphism.In some cases, these features would have formed simultaneously with the deposition of the eolian dusttrapped by grass. The degree of pedogenesis would depend on the ratio between the intensity of theaccretion and reworking processes, and pedogenesis. The sedimentary units were affected partially ortotally by pedogenesis.Two zones rich in volcanic glass were detected at San Pedro profile; new information reveals thesame situation near La Plata city. The uppermost zone, with 2030% volcanic glass, constitutes in somecases the parent material of the present soil; the deeper zone, contains 5070% volcanic glass.Micromorphological observations confirm the presence of scarce to abundant clasts of old illuvial horizonsand loess embedded in the matrix of most of the paleosols.Pedological processes are most evident in the deeper part of the profiles, indicated by a strong gradeof structure and abundant laminated and juxtaposed textural and amorphous features. The lower paleosolscan be considered pedostratigraphic units useful for correlation in the continental border in northeasternBuenos Aires Province, Argentina. 2004 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57221104 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.1 Vol.21 |
| title | Micromorphology of paleosols at the continental border of the Buenos Aires province, Argentina |
| topic | Ciencias de la Tierra Argentina buried soils reworked loess micromorphology |
| url | https://www.redalyc.org/articulo.oa?id=57221104 |