A compilation of 29,574 published radiometric dates for metamorphic rocks from the South American Andes and adjacent parts of South America have been tabulated for access by researchers via GEOROC Expert Datasets. The compilation exists as a spreadsheet for access via MS Excel, Google Sheets, and other spreadsheet applications. Initial igneous compilations were utilized in two publications by the author, Pilger (1981, 1984). The compilations have been added to in subsequent years with the metamorphic and sedimentary compilations separated in the last few years. Locations in latitude and longitude are largely taken from the original source, if provided, with UTM locations maintained and converted; in some cases, sample locations were digitized from electronic maps if coordinates were otherwise not available. Analytical results are not included to prevent the files from becoming too large. The existing compilation incorporates compilations by other workers in smaller regions of the Andes. References to original and compilation sources are included.
While I am updating reconstructions of the South American and Nazca/Farallon plates, incorporating recent studies in the three oceans, for comparison with the igneous dates for the past 80 m. y., it is hoped that the spreadsheets will be of value to other workers.
Reliability: In most cases the data have been copy/pasted from published or appendix tables. In a few cases, the location has been digitized from published maps; the (equatorial equidistant) maps were copied into Google Earth and positioned according to indicated coordinates, with locations digitized and copied/pasted into the spreadsheet. (It is possible that published maps are conventional Mercator-based, even if not so identified, rather than either equatorial equidistant or Universal Transverse Mercator; this can be a source of error in location. For UTMs, the errors should be minor.) Duplicates are largely recognized by equivalent IDs, dates, and uncertainties. Where primary sources have been accessed, duplicate data points in compilations are deleted. (Analytic data are NOT included.)
This compilation is part of a series. Companion compilations of radiometric dates from igneous and sedimentary rocks are available at https://doi.org/10.5880/digis.e.2023.005 and https://doi.org/10.5880/digis.e.2023.006, respectively.
This data set is the 4th contribution of a series reporting chemical data for accessory minerals from felsic igneous rocks. It deals with two late Variscan biotite-granite massifs emplaced in the Saxothuringian Zone of the Variscan Orogen (Erzgebirge−Vogtland metallogenic province) in Germany. Mineral compositions were measured by electron-microprobe on surface rocks and borehole samples.The data set assembles the results of electron-microprobe spot analyses of primary and secondary allanite-(Ce), monazite-(Ce), xenotime-(Y) and zircon from the multi-phase biotite-granite plutons of Kirchberg (KIB, Western Erzgebirge) and Niederbobritzsch (NBZ, Eastern Erzgebirge). Both plutons comprise several, compositionally and texturally distinct sub-intrusions, contain locally centimeter- to decimeter-sized co-genetic enclaves and xenoliths, and are cross-cut by chemically distinct, fine-grained aplitic dikes. These late-Variscan (c. 325 Ma) granites are moderately to highly evolved and (not considering enclaves) span the SiO2-range (in wt%) 67.0-77.4 (KIB) and 66.8-76.2 (NBZ). The granites are weakly peraluminous (A/CNK = 1.04−1.11 for KIB and 0.99-1.10 for NBZ) and of transitional I−S-type affinity.Formation of primary allanite-(Ce) was restricted to the least-evolved subintrusions KIB1 and NBZ1 of both massifs. All other granites contain monazite-(Ce) as predominant LREE host. Magmatic allanite-(Ce) is variably altered and characterized by totals <100 wt%, implying the presence of several wt% water in the structure. Synchysite-(Ce) constitutes one of its alteration minerals. The Kirchberg massif hosts a second sub-facies of KIB1 that contains monazite instead of allanite as primary species. Severe alteration of this granite facies gave rise to partial or complete dissolution of part of the monazite accompanied by formation of allanite-epidote solid solutions as alteration product. Monazite-(Ce) displays large variations in Th versus REE concentrations even at thin-section scale. Incorporation of Th is mainly governed by the huttonite substitution Th^4+ + Si^4+ = REE^3+ + P^5+. Thorium concentrations span the range 1.33 – 41.8 wt.% ThO2. Xenotime-(Y) does not occur in KBI1 and NBZ1, but crystallized in all other subintrusions. Notable is the predominance of the heaviest REE Er-Lu (normalized to chondrite).The data set contains the complete pile of electron-microprobe analyses for the four accessory minerals allanite-(Ce) (ALLA-KIB-NBZ2019), monazite-(Ce) (MONA-KIB-NBZ2019), xenotime-(Y) (XENO-KIB-NBZ2019) and zircon (ZIRC-KIB-NBZ2019). All tables are presented as Excel (xlsx) and machine-readable csv formats. The content of the tables and further data description are given in the data description file, together with BSE images of primary and secondary allanite-(Ce) from the KIB1 subintrusion.