Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America
The Agua Colorada Formation crops out in the Famatina System (northwestern Argentina) and is composed of sandstones, conglomerates, mudstones, some coal seams, and diamictites. The diamictites are not abundant in the formation, but they form thick beds in the lower member. The diamictites are divide...
Guardado en:
Autor principal: | |
---|---|
Publicado: |
1990
|
Materias: | |
Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v3_n1_p9_Limarino http://hdl.handle.net/20.500.12110/paper_08959811_v3_n1_p9_Limarino |
Aporte de: |
id |
paper:paper_08959811_v3_n1_p9_Limarino |
---|---|
record_format |
dspace |
spelling |
paper:paper_08959811_v3_n1_p9_Limarino2023-06-08T15:48:39Z Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America Gutierrez, Pedro Raúl Agua Colorado Formation Carboniferous diamictite Famatina System glaciation tillite Argentina The Agua Colorada Formation crops out in the Famatina System (northwestern Argentina) and is composed of sandstones, conglomerates, mudstones, some coal seams, and diamictites. The diamictites are not abundant in the formation, but they form thick beds in the lower member. The diamictites are divided into two major genetic types; the first is interpreted as resedimented lacustrine diamictites and therefore is not considered a tillite. The massive diamictites included in the second type are considered true tillites. The principal features that suggest a glacial origin are: 1) very poor sorting; 2) small grain size (clay to very fine sand) of the matrix; 3) massive bedding; 4) existence of faceted and striated clasts; and 5) very close relationship with lacustrine sequences containing dropstones. According to Eyles' methodology, several lithofacies have been recognized in the diamictites of the Las Gredas locality: Dmm, Dcm, Dcs, and Dcg. Dmm (matrix-supported massive diamictites) and Dcm (clast-supported massive) are the most frequent and very probably represent tillitic deposits. The Dcs (clast-supported stratified) and Dcg (clast-supported graded) lithofacies are interpreted as originated by slides and gravity flows. The finding of a rich palynological assemblage obtained in lacustrine deposits (closely associated with the diamictites) allows the dating of the glacial event as early Late Carboniferous. This age is based on the presence of diagnostic cosmopolitan taxa together with monosaccate pollen grains. © 1990. Fil:Gutierrez, P. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1990 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v3_n1_p9_Limarino http://hdl.handle.net/20.500.12110/paper_08959811_v3_n1_p9_Limarino |
institution |
Universidad de Buenos Aires |
institution_str |
I-28 |
repository_str |
R-134 |
collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
topic |
Agua Colorado Formation Carboniferous diamictite Famatina System glaciation tillite Argentina |
spellingShingle |
Agua Colorado Formation Carboniferous diamictite Famatina System glaciation tillite Argentina Gutierrez, Pedro Raúl Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America |
topic_facet |
Agua Colorado Formation Carboniferous diamictite Famatina System glaciation tillite Argentina |
description |
The Agua Colorada Formation crops out in the Famatina System (northwestern Argentina) and is composed of sandstones, conglomerates, mudstones, some coal seams, and diamictites. The diamictites are not abundant in the formation, but they form thick beds in the lower member. The diamictites are divided into two major genetic types; the first is interpreted as resedimented lacustrine diamictites and therefore is not considered a tillite. The massive diamictites included in the second type are considered true tillites. The principal features that suggest a glacial origin are: 1) very poor sorting; 2) small grain size (clay to very fine sand) of the matrix; 3) massive bedding; 4) existence of faceted and striated clasts; and 5) very close relationship with lacustrine sequences containing dropstones. According to Eyles' methodology, several lithofacies have been recognized in the diamictites of the Las Gredas locality: Dmm, Dcm, Dcs, and Dcg. Dmm (matrix-supported massive diamictites) and Dcm (clast-supported massive) are the most frequent and very probably represent tillitic deposits. The Dcs (clast-supported stratified) and Dcg (clast-supported graded) lithofacies are interpreted as originated by slides and gravity flows. The finding of a rich palynological assemblage obtained in lacustrine deposits (closely associated with the diamictites) allows the dating of the glacial event as early Late Carboniferous. This age is based on the presence of diagnostic cosmopolitan taxa together with monosaccate pollen grains. © 1990. |
author |
Gutierrez, Pedro Raúl |
author_facet |
Gutierrez, Pedro Raúl |
author_sort |
Gutierrez, Pedro Raúl |
title |
Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America |
title_short |
Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America |
title_full |
Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America |
title_fullStr |
Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America |
title_full_unstemmed |
Diamictites in the Agua Colorada Formation (northwestern Argentina): New evidence of Carboniferous glaciation in South America |
title_sort |
diamictites in the agua colorada formation (northwestern argentina): new evidence of carboniferous glaciation in south america |
publishDate |
1990 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_08959811_v3_n1_p9_Limarino http://hdl.handle.net/20.500.12110/paper_08959811_v3_n1_p9_Limarino |
work_keys_str_mv |
AT gutierrezpedroraul diamictitesintheaguacoloradaformationnorthwesternargentinanewevidenceofcarboniferousglaciationinsouthamerica |
_version_ |
1768544280992808960 |