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Geochemical and Modal Data for Mesoproterozoic Igneous Rocks of the St. Francois Mountains, Southeast Missouri

March 13, 2018

This data release accompanies the Data Series report 'Compilation of new and previously published geochemical and modal data for Mesoproterozoic igneous rocks of the St. Francois Mountains, southeast Missouri (https://doi.org/10.3133/ds1080). The compilation includes recently acquired as well as previously published geochemical and modal petrographic data for igneous rocks in the St. Francois Mountains, southeast Missouri, and supports an ongoing effort to understand the regional geology and ore deposits of the Mesoproterozoic basement rocks of southeast Missouri, USA. This data release includes geochemical data that are (1) newly acquired by the U.S. Geological Survey (USGS) and (2) compiled from numerous sources published during the last fifty-five years. These data are required for ongoing petrogenetic investigations of these rocks. This data release also contains selected data for Mesoproterozoic igneous rocks that were previously published in three U.S. Geological Survey (USGS) data releases (Day and Granitto, 2014; Day, Granitto, and others, 2016, and Granitto and others, 2017). These previously published USGS products include sample description, sample locations, and major oxide and trace element determinations for Mesoproterozoic igneous samples, as well as other samples collected in southeast Missouri by the USGS from the late 1980s through 2017. In this data release, field notes pertinent to the 2015-2017 samples, prefixed with MO15, MO16, and MO17 and where '_xxx' is the individual sample number, are included as Appendix 1 in the Microsoft Excel file 'DS1080_appendix1_MO15_17_Field_Notes.xlxs' file and in its derivative ASCII tab-delimited text file. Data attributes in these files include the field number (Field_ID), location (Latitude, Longitude), rock type (Rock_Type), description of the rock and (or) outcrop from which the sample was collected (Rock_Description), the alteration minerals observed in the field (Alt_Minerals), and their mode of occurrence (Alt_Style). For completeness, the field notes files also include descriptive information for samples without corresponding geochemical analyses. Prior investigations report compositional data for Mesoproterozoic igneous rocks in the St. Francois Mountains that contribute significantly to the understanding of the geochemistry of the region. These data have been compiled during our investigations and are reported herein. For an individual sample to be included in our compilation, a minimum data set consisting of a sample identification value, location information, and a major oxide analysis was required. Additional data were included when available. As a result of this compilation, data for 618 unaltered samples and 549 altered samples were identified and included in this data release as Appendix 2, the Microsoft Excel file 'DS1080_appendix2_SE_MO_ChemData.xlsx,' and its derivative ASCII tab-delimited text files 'DS1080_appendix2SE_MO_ChemData_FreshUnaltered.txt' and 'DS1080_appendix2_SE_MO_ChemData_AlteredMineralized.txt'. Data sources, including published reports and theses, are itemized and tabulated in the Data_Src field in Appendix 2. Along with the data found in Day and Granitto, 2014; Day, Granitto, and others, 2016, and Granitto and others, 2017, this compilation process has likely resulted in the identification and incorporation of the majority of compositional data available for Mesoproterozoic igneous rocks in the St. Francois Mountains, Missouri. Compiling analytical methods and associated estimates of precision and accuracy associated with previously published data is beyond the scope of this effort. Analytical protocols, precision, and accuracy were highly variable among the previous publication sources. Fortunately, most publications document these parameters and details can be retrieved by referring to the original publication identified in the Data_Src field. Background documentation for some samples or analytical data presented in this data release may be incomplete, misleading, or incorrect, any of which could result in the inclusion of inappropriate information in the data set. All efforts have been made to exclude inappropriate samples or misleading data; the amount of inappropriate data inadvertently included in the data set is probably small and is unlikely to significantly affect data interpretation.