The Orange Tuff is an informally named tephra-fall deposit that crops out extensively in the volcanic highlands to the south and southwest of Bogor, West Java, Indonesia. The data included in this data release documents the deposit thickness and maximum sizes of lithics present at sites throughout its distribution. Additional tables document dispersal areas calculated from within hand-drawn isopach and lithic isopleth maps based on the aforementioned thickness and lithic size data. Such area measurements will be used in the related subsequent publication listed in the metadata to derive eruption and deposit characteristics such as bulk volume and column height and to help determine the source volcano. The isopach and isopleth maps will also be reported as figures in the subsequent publication. Additional tables contain geochemical data from electron microprobe analyses of constituent plagioclase, Fe-Ti oxides, and orthopyroxenes. All analyses were carried out at Nanyang Technological University's electron microprobe laboratory. Analyses for plagioclase and pyroxenes were carried out using a 10 μm beam diameter, 15 keV accelerating voltage, and 20 nA beam current. Analyses for Fe-Ti oxides were carried out using a concentrated point beam, 15 keV accelerating voltage, and 20 nA beam current. Repeat geochemical analyses of standard reference materials yielded analytical uncertainty at the 99% confidence level of less than 1% of reported values. Detection limits for analyses of Fe-Ti oxides are as follows: TiO2 (0.02%), Al2O3 (0.013%), Cr2O3 (0.019%), FeO (0.018%), MnO (0.013%), MgO (0.011%). Detection limits for analyses of pyroxenes are as follows: SiO2 (0.02%), TiO2 (0.02%), Al2O3 (0.013%), FeO (0.013%), MnO (0.013%), MgO (0.011%), Na2O (0.007%). Detection limits for analyses of plagioclase are as follows: SiO2 (0.02%), TiO2 (0.02%), Al2O3 (0.011%), FeO (0.018%), MnO (0.013%), MgO (0.01%), CaO (0.006%), Na2O (0.007%), and K2O (0.004%). To maintain data quality, plagioclase and pyroxene analyses with totals below 98.5% and exceeding 101% were excluded. For magnetite, analyses with totals below 91.5% and exceeding 95.25% were excluded, which correspond to totals of 98% and 101% after adjustment for allowable stoichiometric substitution of ferric and ferrous iron were excluded. For ilmenite, analyses with totals below 96.4% and exceeding 99.7% were excluded, which correspond to totals of 98% and 101% after adjustment for allowable stoichiometric substitution of ferric and ferrous iron were excluded.
|Title||Isopach, lithic isopleth, and pyroxene, Fe-Ti oxide, and plagioclase geochemistry data for the Orange Tuff, West Java, Indonesia|
|Authors||Harpel Christopher J., Stimac James, Kushendratno, Rodriguez de Harpel Cecilia F.A., Primulyana Sofyan|
|Product Type||Data Release|
|Record Source||USGS Digital Object Identifier Catalog|
|USGS Organization||Volcano Hazards Program Office|