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Robert R. Seal, II

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The table contains oxide and cation compositions of olivine grains from drill core of the Duluth Complex, Minnesota. The oxides were determined by electron probe microanalysis (EPMA) and are reported in weight percent (wt%). The cations were calculated based on the oxide compositions and are reported in mole percent (mol%). Olivine is a magnesium iron orthosilicate mineral with the formula (Mg2+, Fe2+)2SiO4. Olivine forms a solid solution series with magnesium (Mg) at one end and iron (Fe) at the other. Forsterite (Mg2SiO4) is the magnesium endmember and fayalite (Fe2SiO4) is the iron endmember. Minor elements can substitute into the crystal structure, such as manganese (Mn) and nickel (Ni). To better understand...
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This worksheet displays the results of X-ray diffraction (XRD) analyses of samples from the Ironwood Iron-Formation. Samples were analyzed using a PANalytical X'Pert Pro diffractometer using Co radiation and the results interpreted using Highscore Plus v.4.5. Mineral abundances were determined by Rietveld refinement. First posted October 10, 2018 Revised April 2019, ver. 2.0
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The table contains oxide and cation compositions of pyroxene grains from drill core in the Duluth Complex. The oxides were determined by electron probe microanalysis (EPMA) and are reported in weight percent (we%). The cations were calculated from the oxide concentrations and are reported in mole percent (mol%). Pyroxene minerals are a group of rock-forming inosilicate minerals with calcium (Ca), iron (Fe), and magnesium (Mg) endmembers. Wollastonite (Wo) is the Ca-endmember with the formula Ca2Si2O6. Ferrosilite (Fs) is the Fe-endmember with the formula Fe2Si2O6, and enstatite (En) is the Mg-endmember with the formula Mg2Si2O6. In order to better understand the chemical compositions of the pyroxenes, the percent...
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The table contains oxide and cation compositions of feldspar grains from drill core of the Duluth Complex. The oxides were determined by electron probe microanalysis (EPMA) and are are reported in weight percent (wt%). The cations were then calculated and are reported in mole percent (mol%). Feldspar grains are a group of rock-forming tectosilicate minerals with potassium (K), sodium (Na), and calcium (Ca) endmembers. Anorthite has a chemical formula CaAlSi3O8; albite has the formula NaAlSi3O8; and orthoclase has the chemical formula KAlSi3O8. To better understand the composition of the measured feldspars, we calculated the anorthite content (An%) as (Ca/(Ca+Na+K)) x 100 and report the values in mol%. Albite (Ab%)...
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This table reports major, minor, and trace element compositions of bulk drill core samples from the Duluth Complex, Minnesota. Major elements were measured using wavelength dispersive X-ray fluorescence (XRF) and inductively coupled plasma atomic emission spectrometry (ICP-AES); minor and trace elements were determined using ICP-AES, inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HGAAS). Total carbon, carbonate carbon, and total sulfur were also analyzed. Total carbon was measured by combustion followed by infrared detection on LECO instrumentation. Carbonate carbon in the bulk rock samples was determined as carbon dioxide by coulometric titration. Total...
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