PAIRED (U-Th)/(He-Pb) DOUBLE DATING OF DETRITAL ZIRCON AND DETRITAL MONAZITE DISTINGUISHES ACADIAN FORELAND SEDIMENTARY PROVENANCE RESPONSE TO OROGENIC AND CLIMATIC SHIFTS (Invited Presentation)

The Paleozoic Appalachian orogen extends >3,000 km from Newfoundland through Alabama and is composed of a mosaic of terranes representing multiple collisional orogenic phases. The Devonian–Mississippian Acadian orogenic phase is characterized by the accretion of the Avalonia and Carolina terranes, growth of an orogenic plateau, a global decrease in temperature, and a series of marine mass extinctions. However, the interactions between orogenic topographic growth and changes in sediment routing during major shifts in Late Paleozoic climate remain unclear. Reconstructing Acadian sediment dispersal and orogenic exhumation is key to understanding the Paleozoic tectonic, climatic, and biologic evolution of eastern Laurentia. The sedimentary record of these processes is archived in the ~18 km thick Appalachian foreland, including the >3 km thick Devonian–Mississippian Catskill-Pocono siliciclastic wedge. Here, we present new double-dated detrital zircon (U-Th)/(He-Pb) and detrital monazite Th-Pb data from the Catskill-Pocono wedge. Detrital zircon U-Pb age spectra are dominated by Taconic (490–420 Ma) and Grenville (1350–900 Ma) ages and include minor Pan-African (700–500 Ma) and Laurentian craton (1900–1600 Ma) ages. In contrast, detrital monazite Th-Pb ages are mainly Acadian (425–375 Ma). When compared with potential sediment sources, detrital zircons are unable to pinpoint specific sources; however, when paired with detrital monazite, a northern Appalachian source is identified for the Catskill-Pocono wedge. Further, a provenance shift across the Late Devonian glaciation suggests changes in hinterland sediment routing during glaciation. The (U-Th)/He dates from Grenville and Taconic age detrital zircons range from 440 to 249 Ma and are interpreted as Taconic to Acadian synorogenic cooling and exhumation. The new results are synthesized into a holistic provenance reconstruction across the Acadian foreland basin. These results are not only important for understanding Acadian hinterland evolution and sediment dispersal, but bear on provenance interpretations and potential for sediment recycling during post-Acadian tectonics and sediment routing reconstructions across Laurentia.