Geological Society of America

T294 Laurentian Evolution during the Late Mississippian to Early Permian: Interactions and Feedbacks between Tectonism, Climate, and Sedimentary Systems

Wednesday, 25 September 2019
1:30 PM - 5:30 PM
Room 228AB, North Building

RECONSTRUCTING LATE PALEOZOIC LAURENTIAN SEDIMENT DISPERSAL VIA MIXTURE MODELLING OF DETRITAL ZIRCON U-PB AGES

Paper number: T294-9
Program: Technical Sessions
Time: 3:35 PM – 3:55 PM

Authors

Joel Saylor Presenting Author
University of British Columbia, Vancouver, BC
Tyson Smith
University of Houston, Houston, CO
Ryan J. Leary
New Mexico Institute of Mining and Technology, Socorro, NM
Thomas J. Lapen
University of Houston, Houston, CO
Paul J. Umhoefer
Northern Arizona University, Flagstaff, AZ
Michael Smith
Northern Arizona University, Flagstaff, AZ
Gregory L.E. Burr
Northern Arizona University, Flagstaff, AZ
Emma Lodes
Northern Arizona University, Flagstaff, AZ
Daniel J. Foley
Northern Arizona University, Flagstaff, AZ

Abstract

Late Paleozoic orogenesis in along both the margins and SW interior of Laurentia resulted in regional sediment provenance changes marked by integration, disruption, and reintegration of west or southwest directed transcontinental sediment dispersal systems. We characterize changes in sediment provenance using a combination of forward and inverse mixture modelling of detrital zircon U-Pb age spectra. Late Paleozoic samples are best characterized as mixtures of eight unique sources based on inverse mixture modelling of 108 samples or groups of samples from across Laurentia. Samples are divided into five time intervals spanning the Mississippian–middle Permian.

Mixing proportions reveal a provenance gradient in the Mississippian, with samples from the eastern USA having a significant Appalachian contribution and samples in the southwest Laurentia having a strong western Laurentian affinity. This changes in the Early Pennsylvanian accompanying the onset of ARM and Alleghanian orogenesis. During the Early Pennsylvanian inverse mixture modelling shows consistently high Appalachian proportions across the USA, except for the Central Colorado Trough and proximal Denver Basin where a significant component is ascribed to local basement sources. However, in the Middle Pennsylvanian–early Permian, the proportion of Appalachian detritus west of the ARM decreases while the region of the ARM dominated by local basement-sourced detritus expands. By the middle Permian Appalachian-sourced detritus again dominates in all basins. These observations suggest that the ARM province was an effective barrier to westward sediment dispersal to ARM basins or southwestern Laurentia during ARM orogenesis.

Forward mixture modelling of the Paradox Basin confirms the tectonic isolation of the ARM basins during ARM orogenesis, and points to a method to integrate lithofacies, sediment thickness, and sediment provenance data into spatially referenced maps.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-335178

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