Major and trace element geochemical data for the Petersburg Granite (sensu stricto), Pocoshock Creek Gneiss, and related Appalachian igneous rocks

The Dinwiddie terrane, formerly the Petersburg Granite (sensu lato), was originally interpreted as a Pennsylvanian - Permian igneous complex located in the eastern Piedmont of Virginia and considered to be a single batholith that comprises different textural varieties, likely assumed to have been emplaced from a single source during Alleghanian metamorphism (Bloomer 1939; Bobyarchick, 1978; Bobyarchick and Glover, 1979). However, mapping in the 2000s and 2010s (Carter and others, 2007; 2010; Carter, 2010; Bleick and others, 2011; Bondurant and others, 2011; Occhi and others, 2015, 2017; Occhi and Swanger, 2019) divided this into five distinct units based on lithology, including a subidiomorphic granite, a porphyritic granite, a foliated granite, a layered granite gneiss, and a megacrystic granite. Though these varieties of granite and gneiss were originally considered to be part of the same unit, Carter and others (2023) evaluated each of these five lithologies on the bases of their geochemistry and geochronology, and determined that the foliated granite and layered granite gneiss are ~100 million years older than the other lithologies and that they record evidence of a different magma source than the subidiomorphic granite, porphyritic granite, and megacrystic granite, prompting the redefinition of the Petersburg Granite (sensu lato) into the Dinwiddie terrane, which encompasses the entire suite of granites and gneisses formerly referred to as the Petersburg Granite (sensu lato). The Dinwiddie terrane can then be divided into the Petersburg Granite (sensu stricto), which is composed of the subidiomorphic granite, porphyritic granite, and megacrystic granite lithologies, and the informal Pocoshock Creek Gneiss, which is composed of the foliated granite and layered granite gneiss.

Despite this redefinition, their work did not establish the Pocoshock Creek Gneiss as a formal lithodemic unit per the North American Commission on Stratigraphic Nomenclature (2021). Therefore, in order to better characterize the Pocoshock Creek Gneiss, justify its division from the Petersburg Granite (sensu stricto), and define this unit formally, geochemical data from these two units are compared. This data release comprises unpublished geochemical data collected during the work of Carter and others (2023), as well as a compilation of published geochemical data from Carter and others (2023) and from various igneous intrusions throughout the southern Appalachians for comparison with the Petersburg Granite (sensu stricto) and Pocoshock Creek Gneiss. The sources of all geochemical data included in this data release are described further within this metadata.


Note, any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.