39 D7. Sedimentary Geology, Geomorphology, and Karst

Friday, 8 April 2022
1:30 PM - 5:30 PM
North Meeting Room 212

THERE AND BACK AGAIN: THE RECYCLING OF APPALACHIAN AND GRENVILLE SIGNATURES IN DZ U-PB RECORDS OF PHANEROZOIC NORTH AMERICA

Paper number: 39-3
Program: Technical Sessions
Time: 2:00 PM – 2:15 PM

Authors

Abstract

The detrital zircon (DZ) U-Pb signature of the Appalachian-Ouachita orogenic system, which includes the Grenville (1250–950 Ma) and Appalachian (500–275 Ma) age groups, dominates the entire Phanerozoic record of North America. An east-to-west comparison of DZ samples across North America (late Paleozoic to present), demonstrates a persistent Appalachian signature for samples, including a “recycled” Appalachian signature in the West. Lower Pennsylvanian deposits proximal to the Appalachian orogen are composed of ~50–75% Appalachian- and Grenville-age DZ, representing a “primary” Appalachian signature. The Ouachita Basin received contributions from the Appalachians and the midcontinent, resulting in a “diluted” primary Appalachian signature. By the Triassic the DZ record out West displays a primary Appalachian signature and represents rivers sourced from the Appalachian-Ouachita-Marathon highlands.

DZ sampled from Mesozoic fluvial sandstones, such as along the Front Range, indicate drainage reversal due to the rise of the Western Cordillera; yet a persistent Appalachian signature exists in these western-sourced, eastward-flowing systems—a phenomenon that continues to the present. None of these systems are interpreted to be sourced by primary Appalachian or Grenville terranes, suggesting a recycled Appalachian signature. These western samples frequently are composed of >40% Appalachian- and Grenville-age DZ and accompanied by “western” age groups (e.g., Yavapai-Mazatzal and Western Cordillera). This is representative of west-to-east flowing Jurassic to Holocene rivers of western North America. Although western drainage reorganization reversed the trajectory of sediment routing sourced by the Appalachian-Ouachita orogen, Western Cordillera-age DZ are underrepresented across the continent, even in the West. The persistent Appalachian signature continues to have an outsized presence in the DZ record of North America.

Geological Society of America Abstracts with Programs. Vol. 54, No. 4

doi: 10.1130/abs/2022NC-373575

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