| Abstract: | An inter-laboratory comparison has been made of X-ray fluorescence analyses of 10 samples of lava and pumices from El Chicho??n Volcano, Chiapas, Mexico. Some determinations of major-element constituents agree within analytical uncertainty, whereas others exchibit significant bias. Analyses carried out at the Michigan Technological University (MTU) laboratory are systematically lower in MgO (26-48%), Fetotal(5-18%), CaO (4-15%) and higher in K2O (0-15%) than analyses made at the U.S. Geological Survey (USGS) Denver laboratory. These differences are ascribed in part to a complex combination of calibration assumptionsand mineralogical and particle-size effects inherent in the use of pressed rock-powder pellets in the analytical procedure of the MTU laboratory. Other, but as yet unknown, differences in sample preparation and/or analytical technique may also be important; effects related to natural sample inhomogeneityare believed to be insignificant. The inter-laboratory differences in the analytical data complicated accurate assessment of whether El Chicho??n magmas have changed composition during the past 300 000 a. Knowledge of such change is needed for understanding petrogenetic history and for such related studies as evaluation of volcanic hazards. ?? 1987. |
| Genre: | Article |
| ProdID: | 70014594 |
| Citation Author: | Tilling, R. I.; Bornhorst, T. J.; Taggart, Jr. , J. E.; Rose, W. I.; McGee, J. J. |
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| Citation End Page: | 345 |
| Citation Issue: | 3 |
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| Citation Language: | English |
| Citation Larger Work Title: | Applied Geochemistry |
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| Citation Number Of Pages: | 9 |
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| Citation Search Results Text: | Inter-laboratory comparison of X-ray fluorescence analyses of eruptive products of El Chicho??n Volcano, Chiapas, Mexico; 1987; Article; Journal; Applied Geochemistry; Tilling, R. I.; Bornhorst, T. J.; Taggart, Jr. , J. E.; Rose, W. I.; McGee, J. J. |
| Citation Start Page: | 337 |
| Citation Volume: | 2 |
| Citation Year: | 1987 |
| Type: | citation/reference |
| Text: | Inter-laboratory comparison of X-ray fluorescence analyses of eruptive products of El Chicho??n Volcano, Chiapas, Mexico; 1987; Article; Journal; Applied Geochemistry; Tilling, R. I.; Bornhorst, T. J.; Taggart, Jr. , J. E.; Rose, W. I.; McGee, J. J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Thu, 1 Jan 1987 00:00 -0600 |
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