Abstract In Mississippi, USA, exposures of fossiliferous Cretaceous and Paleogene strata contributed to geological investigations for more than 200 years. Since 2012, four Mississippi fossiliferous field sites were regularly integrated within university palaeontology classrooms, with community engaged learning (CEL) introduced in 2018. Through CEL projects, the students assisted local organizations with optimizing and/or protecting local fossiliferous sites. Analysis of student surveys demonstrated that students were overwhelmingly positive toward local field sites and CEL inclusion in the palaeontology courses. Students acknowledged ‘real-world’ interdisciplinary CEL experiences moved them beyond the palaeontology content and made them stakeholders in modern issues. While these four sites contain landscapes that qualify as local geoheritage sites because of their educational and potential geotourism value, only one site, W.M. Browning Cretaceous Fossil Park, is preserved for future generations. The other sites (Blue Springs, Osborn Prairie, Smith County) face challenges in their long-term sustainability.

ABSTRACT The southern Appalachian western Blue Ridge preserves a Mesoproterozoic and mid-Paleozoic basement and Neoproterozoic to Ordovician rift-to-drift sequence that is metamorphosed up to sillimanite grade and dissected by northwest-directed thrust faults resulting from several Paleozoic orogenic events. Despite a number of persistent controversies regarding the age of some western Blue Ridge units, and the nature and extent of multiple Paleozoic deformational/metamorphic events, synthesis of several multidisciplinary data sets (detailed geologic mapping, geochronology and thermochronology, stable-isotope chemostratigraphy) suggests that the western Blue Ridge likely records the effects of two discrete orogenic events. The earlier Taconic (470–440 Ma) event involved a progression from open folding and emplacement of the Greenbrier–Rabbit Creek and Dunn Creek thrust sheets as a foreland fold-and-thrust to low-grade hinterland system (D 1A ), followed by deep burial (>31 km), pervasive folding of the earlier-formed fault surfaces, and widespread Barrovian metamorphism (D 1B ). Because this high-grade (D 1B ) metamorphic event is recorded in Ordovician Mineral Bluff Group turbidites, this unit must have been deposited prior to peak orogenesis, possibly as a foreland basin or wedge-top unit in front of and/or above the developing fold-and-thrust belt. The later Alleghanian (325–265 Ma) event involved widespread northwest-directed brittle thrusting and folding related to emplacement of the Great Smoky thrust sheet (D 2 ; hanging wall of the Blue Ridge– Piedmont thrust). Mid-Paleozoic 40 Ar/ 39 Ar muscovite ages from western Blue Ridge samples likely record post-Taconic cooling (hornblende and some muscovite 40 Ar/ 39 Ar ages) and/or Alleghanian thrust-related exhumation and cooling (ca. 325 Ma muscovite 40 Ar/ 39 Ar and 300–270 Ma zircon fission-track ages), as opposed to resulting from a discrete Neoacadian thermal-deformational event. The lack of evidence for a discrete Neoacadian event further implies that all deformation recorded in the Silurian–Mississippian(?) Maggies Mill–Citico Formation must be Alleghanian. We interpret this structurally isolated sequence to have been derived from the footwall of the Great Smoky fault as an orphan slice that was subsequently breached through the Great Smoky hanging wall along the out-of-sequence Maggies Mill thrust.

Abstract Independent researchers working in the Talladega belt, Ashland-Wedowee-Emuckfaw belt, and Opelika Complex of Alabama, as well as the Dahlonega gold belt and western Inner Piedmont of Alabama, Georgia, and the Carolinas, have mapped stratigraphic sequences unique to each region. Although historically considered distinct terranes of disparate origin, a synthesis of data suggests that each includes lithologic units that formed in an Ordovician back-arc basin (Wedowee-Emuckfaw-Dahlonega basin—WEDB). Rocks in these terranes include varying proportions of metamorphosed mafic and bimodal volcanic rock suites interlayered with deep-water metasedimentary rock sequences. Metavolcanic rocks yield ages that are Early–Middle Ordovician (480–460 Ma) and interlayered metasedimentary units are populated with both Grenville and Early–Middle Ordovician detrital zircons. Metamafic rocks display geochemical trends ranging from mid-oceanic-ridge basalt to arc affinity, similar to modern back-arc basalts. The collective data set limits formation of the WEDB to a suprasubduction system built on and adjacent to upper Neoproterozoic–lower Paleozoic rocks of the passive Laurentian margin at the trailing edge of Iapetus, specifically in a continental margin back-arc setting. Overwhelmingly, the geologic history of the southern Appalachians, including rocks of the WEDB described here, indicates that the Ordovician Taconic orogeny in the southern Appalachians developed in an accretionary orogenic setting instead of the traditional collisional orogenic setting attributed to subduction of the Laurentian margin beneath an exotic or peri-Laurentian arc. Well-studied Cenozoic accretionary orogens provide excellent analogs for Taconic orogenesis, and an accretionary orogenic model for the southern Appalachian Taconic orogeny can account for aspects of Ordovician tectonics not easily explained through collisional orogenesis.

Large bodies of eclogite in the Eastern Blue Ridge Province of western North Carolina crop out immediately southeast of the Burnsville fault zone, an Acadian dextral strike-slip fault that separates Laurentian Mesoproterozoic basement and Neoproterozoic to early Paleozoic units (Western Blue Ridge) from an inferred accretionary wedge complex (Eastern Blue Ridge). The peak metamorphic assemblage in eclogite is omphacite (Jd 27–35 ) + garnet (Alm 48 Prp 30 Grs 22 ) + quartz + rutile ± zoisite ± zircon ± apatite ± sulfides ± Fe-Ti oxides; evidence of an amphibolite-facies overprint is regionally widespread but variably developed. Geochemical and isotopic characteristics of the eclogites and some surrounding amphibolites are consistent with their derivation from mid-ocean-ridge basalt protoliths. Zircon from the least-altered eclogite yielded a U-Pb, isotope dilution–thermal ionization mass spectrometry age of 459.0 +1.5/−0.6 Ma. Multimineral plus whole-rock Sm-Nd isotopic data indicate that Sm-Nd mineral systematics were disturbed, likely during amphibolite-facies metamorphism. Partly amphibolitized eclogite contains titanite with a U-Pb age of 394 ± 4 Ma; titanite from another sample shows disturbed U-Pb systematics with apparent ages between 448 Ma and 417 Ma. Both eclogite and partly amphibolitized eclogite contain rutile with a U-Pb age of ca. 334–340 Ma. These ages correspond broadly to the time of the Taconian, Acadian, and Alleghanian orogenesis, respectively, and match the timing of metamorphic events and pluton emplacement in the Eastern Blue Ridge Province. The Ordovician geodynamic setting in which the eclogite formed was possibly a complex plate arrangement of island arcs, accretionary complexes, rift basins, and rifted microcontinental blocks, perhaps similar to the Australia-Pacific plate boundary between New Zealand and Papua New Guinea. Taconian collisional orogenesis was either synchronous with or closely followed high-pressure metamorphism, and both Acadian and Alleghanian events completely to partially reset titanite and rutile chronometers.

Abstract The E5 transect extends southeastward from the Cumberland Plateau across the Appalachian orogen, the Atlantic Coastal Plain, Continental Shelf and Slope, and the Blake Plateau Basin; it is a transect through the Precambrian-early Paleozoic and Mesozoic-Tertiary continental margins of North America. The transect consists primarily of a 100-km-wide geologic strip map, a cross section, and supporting geophysical data. The cross section is based on surface geology, surface and subsurface data from Coastal Plain and offshore drill holes, shipboard and aeromagnetic data, and gravity and seismic reflection data, including the ADCOH and COCORP southern Appalachians lines. Elements of the map and cross section include: (1) the Appalachian foreland fold-thrust belt and western Blue Ridge Late Proterozoic-Paleozoic continental margin; (2) the eastern Blue Ridge-Chauga belt-Inner Piedmont oceanic-continental fragment terrane; (3) the volcanicplutonic Carolina terrane containing the middle to late Paleozoic high-grade Kiokee belt; and (4) a major geophysical ly defined terrane beneath the Coastal Plain. Three Paleozoic sutures may be present along the section line: the Hayesville thrust, the Inner Piedmont-Carolina terrane boundary (Taconic or Acadian suture?), and an eastern boundary of the Carolina terrane (Alleghanian? suture) in the subsurface beneath the Coastal Plain. The modern continental margin consists of the terrestrial clastics-filled Triassic-Jurassic basins and offshore marine Jurassic- Cretaceous clastic-carbonate bank succession overlain by younger Cretaceous and Tertiary sediments. Above the Late Cretaceous onshore unconformity lie Cenozoic sediments that represent seaward prograding of the shelf-slope, truncated by Miocene to recent wave abrasion and currents.

Abstract DNAG Transect E-5. Part of GSA's DNAG Continent-Ocean Transect Series, this transect contains all or most of the following: free-air gravity and magnetic anomaly profiles, heat flow measurements, geologic cross section with no vertical exaggeration, multi-channel seismic reflection profiles, tectonic kindred cross section with vertical exaggeration, geologic map, stratigraphic diagram, and an index map. All transects are on a scale of 1:500,000.