Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed
A large amount of calcite pseudomorphs after gypsum were discovered in a volcanic ash bed and its underlying sand/siltstone in the Gering Formation (late Oligocene), northwestern NE, USA. The highly positive 17O anomalies in the residual sulfate indicate that the sulfate could only have come from th...
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ftlouisianastuir:oai:repository.lsu.edu:geo_pubs-1252 2024-09-15T17:46:44+00:00 Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed Bao, Huiming 2005-01-03T08:00:00Z https://repository.lsu.edu/geo_pubs/253 https://doi.org/10.1016/j.chemgeo.2004.08.052 unknown LSU Scholarly Repository https://repository.lsu.edu/geo_pubs/253 doi:10.1016/j.chemgeo.2004.08.052 Faculty Publications 17 O-anomaly Dry fogs Hyperarid deserts Oligocene Playa Sulfate text 2005 ftlouisianastuir https://doi.org/10.1016/j.chemgeo.2004.08.052 2024-08-08T04:27:15Z A large amount of calcite pseudomorphs after gypsum were discovered in a volcanic ash bed and its underlying sand/siltstone in the Gering Formation (late Oligocene), northwestern NE, USA. The highly positive 17O anomalies in the residual sulfate indicate that the sulfate could only have come from the oxidation of sulfur gases by ozone in the atmosphere. We previously proposed that it was most likely the result of an extreme tropospheric sulfate haze (dry fog) event that was associated with volcanic eruptions in the west. To test the dry fog hypothesis, we examine here two alternative scenarios that also involve atmospheric sulfate deposition but do not imply a dramatic volcanic and dry fog source: (1) is it possible that some playas in arid or semiarid regions accumulate the type of atmospheric sulfate deposits as we see in the mid-Gering bed by the inflow of surface water or groundwater? (2) Could a period of hyperaridity and stability during the late Oligocene have caused a significant accumulation of atmospheric background sulfate onto the mid-Gering ash bed surface? Sulfates from a variety of playa settings were collected and measured for their 17O anomalies. The sulfate isotope (both O and S) and concentration profiles of two volcanic ash beds that are currently exposed in the central Atacama Desert (Chile) and in Taylor Valley of the Antarctica Dry Valleys were studied along with their sedimentary features. These two ash beds were chosen for comparison because of their significant levels of atmospheric sulfate accumulated during prolonged and hyperarid climatic conditions. Results showed no or minimal 17O anomalies in any of the playa sulfate samples from around the world, and none of the parameters in the mid-Gering ash profile matches those in either of the two volcanic ash profiles in modern hyperarid settings. Conclusion: The observed 17O-anomalous gypsum deposit in the mid-Gering ash bed is most likely the result of a series of extreme dry fogs that resulted in an intense pulse of atmospheric sulfate ... Text Antarc* Antarctica LSU Digital Commons (Louisiana State University) Chemical Geology 214 1-2 127 134 |
institution |
Open Polar |
collection |
LSU Digital Commons (Louisiana State University) |
op_collection_id |
ftlouisianastuir |
language |
unknown |
topic |
17 O-anomaly Dry fogs Hyperarid deserts Oligocene Playa Sulfate |
spellingShingle |
17 O-anomaly Dry fogs Hyperarid deserts Oligocene Playa Sulfate Bao, Huiming Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed |
topic_facet |
17 O-anomaly Dry fogs Hyperarid deserts Oligocene Playa Sulfate |
description |
A large amount of calcite pseudomorphs after gypsum were discovered in a volcanic ash bed and its underlying sand/siltstone in the Gering Formation (late Oligocene), northwestern NE, USA. The highly positive 17O anomalies in the residual sulfate indicate that the sulfate could only have come from the oxidation of sulfur gases by ozone in the atmosphere. We previously proposed that it was most likely the result of an extreme tropospheric sulfate haze (dry fog) event that was associated with volcanic eruptions in the west. To test the dry fog hypothesis, we examine here two alternative scenarios that also involve atmospheric sulfate deposition but do not imply a dramatic volcanic and dry fog source: (1) is it possible that some playas in arid or semiarid regions accumulate the type of atmospheric sulfate deposits as we see in the mid-Gering bed by the inflow of surface water or groundwater? (2) Could a period of hyperaridity and stability during the late Oligocene have caused a significant accumulation of atmospheric background sulfate onto the mid-Gering ash bed surface? Sulfates from a variety of playa settings were collected and measured for their 17O anomalies. The sulfate isotope (both O and S) and concentration profiles of two volcanic ash beds that are currently exposed in the central Atacama Desert (Chile) and in Taylor Valley of the Antarctica Dry Valleys were studied along with their sedimentary features. These two ash beds were chosen for comparison because of their significant levels of atmospheric sulfate accumulated during prolonged and hyperarid climatic conditions. Results showed no or minimal 17O anomalies in any of the playa sulfate samples from around the world, and none of the parameters in the mid-Gering ash profile matches those in either of the two volcanic ash profiles in modern hyperarid settings. Conclusion: The observed 17O-anomalous gypsum deposit in the mid-Gering ash bed is most likely the result of a series of extreme dry fogs that resulted in an intense pulse of atmospheric sulfate ... |
format |
Text |
author |
Bao, Huiming |
author_facet |
Bao, Huiming |
author_sort |
Bao, Huiming |
title |
Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed |
title_short |
Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed |
title_full |
Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed |
title_fullStr |
Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed |
title_full_unstemmed |
Sulfate in modern playa settings and in ash beds in hyperarid deserts: Implication for the origin of 17 O-anomalous sulfate in an Oligocene ash bed |
title_sort |
sulfate in modern playa settings and in ash beds in hyperarid deserts: implication for the origin of 17 o-anomalous sulfate in an oligocene ash bed |
publisher |
LSU Scholarly Repository |
publishDate |
2005 |
url |
https://repository.lsu.edu/geo_pubs/253 https://doi.org/10.1016/j.chemgeo.2004.08.052 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Faculty Publications |
op_relation |
https://repository.lsu.edu/geo_pubs/253 doi:10.1016/j.chemgeo.2004.08.052 |
op_doi |
https://doi.org/10.1016/j.chemgeo.2004.08.052 |
container_title |
Chemical Geology |
container_volume |
214 |
container_issue |
1-2 |
container_start_page |
127 |
op_container_end_page |
134 |
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1810495093777367040 |